Next Generation Fire Suppression Technology Program 

Final Technical Report 

Enhanced Powder Panels 

December 2003 

Project Identifiers 5E/1/1, 5E/1/12 

SERDP Research Category 6.2

Conducted Under the Direction of the 

U.S. Air Force 46th Test Wing Aerospace Survivability and Safety Flight 

46 OG/OGM/OL-AC 

Sponsored by: 

The Department of Defense 

Strategic Environmental Research and Development Program 

The views and conclusions contained in this document are those of the authors and should not be 

interpreted as representing the official policies, either expressed or implied, of the Strategic 

Environmental Research and Development Program, 46 OG/OGM/OL-AC, or any other part of 

the U.S. Government.
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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 

December 2003 

3. REPORT TYPE AND DATES COVERED 

Final Report 2 Apr 2001 - 31 Aug 2003 

4. TITLE AND SUBTITLE

ENHANCED POWDER PANELS 

6. AUTHOR(S)

DANIEL C. CYPHERS, SKYWARD, LTD. 

5. FUNDING NUMBERS

DASW01-01-P-0623 

F33601-02-F-A208 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

SKYWARD, LTD. 

5100 SPRINGFIELD STREET, SUITE 418 

DAYTON, OHIO 45431-1264

8. PERFORMING ORGANIZATION 

 REPORT NUMBER

SKY-03-01 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

46 OG/OGM/OL-AC 

2700 D STREET, B1661 

WRIGHT-PATTERSON AFB OHIO 

45433-7605

10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 

 

11. SUPPLEMENTARY NOTES 

12.a DISTRIBUTION AVAILABILITY STATEMENT 

AVAILABLE ON-LINE AT www.bfrl.nist.gov 

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words) 

This report documents work performed under the Next Generation Fire Suppression Technology Program to 

identify powder panel concepts for enhancing aircraft dry bay fire suppression performance relative to current 

capability and to demonstrate proofs of concept. Powder panels lining an aircraft dry bay can provide fire 

protection against ballistic impact by releasing powder into the fire zone to inert the space before the 

adjoining fuel spills into the space and is ignited by incendiaries. Current powder panels, which are very 

similar to designs used for decades, have a limited range of performance and have not found wide 

acceptance. This program demonstrated the feasibility of enhanced powder panel concepts, showing new 

designs could afford the following benefits over current commercial powder panel designs: greater powder 

release into the dry bay, better dispersion of powder to prevent ignition off-shotline, longer powder 

suspension to prevent fire ignition for longer periods of time, and increased design flexibility that can be 

utilized to target weight, durability, and application-specific design goals. Enhanced powder panels were 

optimized to target likely aircraft production requirements and live fire tests demonstrated improved 

effectiveness over commercial powder panels at equal or lower weight and thickness. 

15. NUMBER OF PAGES

88 

14. SUBJECT TERMS

powder panels, Next Generation Fire Suppression Technology Program, 

aircraft, dry bay, fire extinguishing, enhanced, optimized 

16. PRICE CODE

17. SECURITY CLASSIFICATION 

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UNCLASSIFIED 

18. SECURITY CLASSIFICATION 

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SAR 

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) 

 Prescribed by ANSI Std. Z39-18 

 298-102 
iii

TABLE OF CONTENTS 

SECTION PAGE

Acknowledgments..........................................................................................................................vi 

1. Introduction.............................................................................................................................. 1 

1.1 Powder Panel Background .............................................................................................. 2 

1.2 Fire Ignition and Powder Panel Effectiveness ................................................................ 3 

2. Task Objectives ....................................................................................................................... 6 

3. Technical Problems ................................................................................................................. 6 

4. General Methodology .............................................................................................................. 7 

4.1 Powder Panel and Application Survey............................................................................ 7 

4.2 Impact Dynamics Experiments ..................................................................................... 11 

4.3 Live Fire Proof-Of-Concept Demonstrations................................................................ 13 

4.3.1 JTCG/AS Demonstration Testing ......................................................................... 14 

4.3.2 FAA Demonstration Testing ................................................................................. 15 

4.4 Parametric/Optimization Experiments .......................................................................... 15 

4.5 Live Fire Demonstration Testing of Optimized Enhanced Powder Panels................... 17 

4.6 Return On Investment Predictions ................................................................................ 18 

5. Technical Results................................................................................................................... 24 

5.1 Impact Dynamics Experimental Results ....................................................................... 24 

5.2 Live Fire Proof-of-Concept Demonstration Test Results ............................................. 32 

5.3 Parametric/Optimization Experimental Results............................................................ 35 

5.4 Live Fire Demonstration Test Results of Optimized Enhanced Powder Panels........... 41 

6. Important Findings and Conclusions..................................................................................... 54 

7. Significant Hardware Developments..................................................................................... 57 

8. Implications for Further Research ......................................................................................... 58

9. References.............................................................................................................................. 59 

10. Bibliography .......................................................................................................................... 61 

11. Appendices ............................................................................................................................ 62 
iv

LIST OF FIGURES 

SECTION PAGE

Figure 1-1. Typical Powder Panel Arrangements .......................................................................... 2 

Figure 4-1. Experimental Test Device and Powder Collection Methods..................................... 12 

Figure 4-2. AVSF Range A Light-Gas Gun................................................................................. 13 

Figure 4-3. JTCG/AS Test Article Setup ..................................................................................... 14 

Figure 4-4. FAA Test Article Schematic ..................................................................................... 15 

Figure 4-5. Test Article Setup...................................................................................................... 18 

Figure 5-1. Test Example of Significant Panel Fracture and Material Loss................................ 28 

Figure 5-2. Test Example of Effective Powder Release and Dispersion ..................................... 29 

Figure 5-3. Effect on Powder Panel Fracture Area of Standard Design Features and Enhanced 

Designs, Showing 15x to 20x More Front Face Area Removed in the Latter ...................... 30 

Figure 5-4. Effect on Powder Delivery of Standard Design Features and Enhanced Designs, 

Showing 5x to 10x Greater Powder Release in the Latter .................................................... 30 

Figure 5-5. Effect on Powder Dispersion of Standard Design Features and Enhanced Designs, 

Showing Greater Dispersion in the Latter............................................................................. 31 

Figure 5-6. Enhanced Powder Panel Fire Mitigation Capability Demonstrated.......................... 33 

Figure 5-7. Comparison Of Commercial And Enhanced Powder Panel Agent Release In 

JTCG/AS Dry Bay Fire Extinguishing Testing..................................................................... 34 

Figure 5-8. Entire Contents of Enhanced Powder Panel Released During FAA Test and Fire 

Prevented............................................................................................................................... 34 

Figure 5-9. Phase II Enhanced Powder Panel Weight Reduction................................................ 37 

Figure 5-10. Phase II Enhanced Powder Panel Thickness Reduction.......................................... 38 

Figure 5-11. Comparing Enhanced and Commercial Panel Powder Release .............................. 38 

Figure 5-12. Comparing Enhanced and Commercial Panel Percent Powder Released ............... 39 

Figure 5-13. Comparing Enhanced and Commercial Panel Front Face Area Removal .............. 40 

Figure 5-14. Post-Test Damage Image of EPP-03 Commercial Powder Panel ........................... 44 

Figure 5-15. Post-Test Damage Image of EPP-04 Enhanced Powder Panel ............................... 45 

Figure 5-16. Post-Test Damage Image of EPP-05 Enhanced Powder Panel ............................... 46 

Figure 5-17. Powder Suspension in the Dry Bay Well After the Test......................................... 47 

Figure 5-18. Powder Dispersion on Striker Plate and Side Lexan Panel..................................... 47 

Figure 5-19. Post-Test Damage Image of EPP-06 Enhanced Powder Panel ............................... 48 

Figure 5-20. Post-Test Damage Image of EPP-07 Enhanced Powder Panel ............................... 49 

Figure 5-21. Post-Test Damage Image of EPP-08 Enhanced Powder Panel ............................... 50 

Figure 5-22. Powder Evident in Dry Bay More Than Five Minutes After EPP-09 Test (Side 

Wall Removed) ..................................................................................................................... 51 

Figure 5-23. Post-Test Damage Image of EPP-09 Enhanced Powder Panel ............................... 52 
v

LIST OF TABLES 

SECTION PAGE

Table 4-1. Examples Of Previously Tested Powder Panel Materials ............................................ 9 

Table 4-2. C-130 Wing Leading Edge Dry Bay Fire Extinguishing System Component Weight 

Estimates ............................................................................................................................... 20 

Table 4-3. C-130 Wing Leading Edge Dry Bay Total Fire Extinguishing System Weight 

Estimates ............................................................................................................................... 21 

Table 4-4. V-22 Outboard Tip Rib Dry Bay Fire Extinguishing System Component Weight 

Estimates ............................................................................................................................... 22 

Table 4-5. V-22 Outboard Tip Rib Dry Bay Total Fire Extinguishing System Weight Estimates

............................................................................................................................................... 23 

Table 5-1. More Effective Powder Panel Designs In Experimental Testing ............................... 26 

Table 5-2. Less Effective Powder Panel Designs In Experimental Testing................................. 27 

Table 5-3. Phase II Optimization Testing .................................................................................... 35

Table 5-3. Phase II Optimization Testing (Continued)................................................................ 36 

Table 5-4. Phase II Enhanced Powder Panel Live Fire Demonstration Tests.............................. 42 
vi

Acknowledgments 

The author would like to gratefully acknowledge the support provided by the Next 

Generation Fire Suppression Technology Program (NGP) with funding provided by the 

Department of Defense’s Strategic Environmental Research and Development Program 

(SERDP). Support for feasibility demonstration testing was also provided by the Joint Technical 

Coordinating Group on Aircraft Survivability (JTCG/AS), now Joint Aircraft Survivability 

Program Office (JASPO), and the Federal Aviation Administration (FAA). 

 Additionally, the author wishes to thank the many individuals and organizations who 

ensured the successful completion of this program. Messrs. Scott Frederick, John Haas, and 

John Vice at Skyward, Ltd. were thoroughly involved in executing the program. Other vital 

support was provided in a variety of forms by Messrs. Doug Hoy and Gary Cunagin at Fox Lite, 

Inc.; Messrs. Martin Lentz, Pat O’Connell, and John Murphy at the Air Force 46th Test Wing’s 

Aerospace Survivability and Safety Flight; Messrs. Joseph Manchor, Richard Mueller, and 

Steven Lundin at the Naval Air Warfare Center-Weapons Division Weapons Survivability 

Laboratory; Messrs. Keith Jochum, Russ Cornetet, Neil Blevins, and many others at General 

Dynamics Advanced Information Engineering Services; Mr. J. Michael Bennett; and Mr. James 

Arehart. 
1

1. Introduction 

 Onboard fires represent a significant hazard to aircraft due to the large quantity of 

flammable fluids carried and the potential for a variety of ignition sources to be present. The 

combat environment for military aircraft or even a terrorist environment for civilian aircraft 

poses a significant fire hazard when a ballistic threat is introduced. These threats are designed to 

act as ignition sources upon penetration of onboard flammable fluid containers. As previous 

combat experience and vulnerability analyses have shown, fire is the most significant 

vulnerability faced by an aircraft subjected to ballistic threat impact. 

Halon 1301, used for fire extinguishing and explosion suppression applications in fielded 

weapon systems, including aircraft, and mission-critical facilities, has been banned from national 

production due to its high ozone-depleting potential. Alternatives developed by industry have 

sizable weight and volume penalties, and their application to fielded current weapon systems 

could require expending large amounts of funding and time. Consequently, the DoD embarked 

on an aggressive new research and development program, the Next Generation Fire Suppression 

Technology Program (NGP). The NGP goal is to develop and demonstrate, by 2005, technology 

for economically feasible, environmentally acceptable and user-safe processes, techniques and 

fluids that meet the operational requirements currently satisfied by halon 1301 systems in 

aircraft. The NGP addresses the predominant fires occurring in aircraft dry bays and engine 

nacelles, focusing resources on identifying and examining promising chemicals and precepts for 

their effective dispersion and distribution in both current and planned platforms. 

One area of focus for the NGP has been improved storage and delivery of fire 

extinguishing agents. Since the production of halon 1301 has been phased out, delivery systems 

that have used it for ballistic threat-induced fire protection in fire zones eventually will require 

some substitute technique. One technique for passively storing and delivering agent upon the 

impact of a ballistic projectile is the use of powder panels. Powder panels have most often been 

applied to the lining of aircraft dry bays to provide passive, lightweight, effective fire protection 

against ballistic impact. Projectile penetration of the dry bay and adjacent fuel tank releases 

agent from the powder panel into the fire zone to inert the space before the adjoining fuel spills 

into the space and is ignited by incendiaries. The recognition of ballistic threat-induced fires as a 

major contributor to aircraft vulnerability and a desire to avoid active halon fire extinguishing 

systems has led to a renewed interest in powder panels as a fire protection device. 

Despite the potential for powder panels as an aircraft fire protection device, commercial 

powder panels are roughly the same design that has existed for decades, and their limited range 

of effectiveness has prevented further implementation in production aircraft. In 2001, the NGP 

embarked on an effort to use current technology and new ideas to examine the feasibility of 

enhanced powder panel designs and demonstrate proofs-of-concept. This report details a twophase effort to accomplish this work (References 1, 2). 
2

1.1 Powder Panel Background 

Powder panels are passive fire protection devices for discharging dry chemical agents to 

prevent or extinguish combat-induced fires in military vehicles. They consist of two walls, an 

internal rib or core structure, and are internally loaded with a fire extinguishing agent, typically a 

dry chemical powder. Historically, commercial powder panels have consisted of thin walls of 

aluminum foil or composite sheets, with an aluminum or Nomex honeycomb core. Typical 

thicknesses for commercial powder panels have been reduced to just over 2.54 mm (0.1 in.). 

Powder panels are typically arranged along the walls of a void area in a military vehicle (called a 

dry bay in an aircraft) adjacent to or on the walls of a flammable fluid container (fuel tank, fuel 

line, hydraulic fluid reservoir, etc.). Figure 1-1 depicts the typical arrangements of powder 

panels. They are typically attached directly to the wall of the flammable fluid container by an 

epoxy adhesive. Testing has shown this arrangement to be more effective than mounting on the 

walls of the dry bay separated from the fluid container (Reference 3). Upon penetration by a 

ballistic projectile, powder panels release powder into the fire zone to inert the space before the 

adjoining fuel spills into the space and is ignited by incendiaries or other ignition sources. 

Fuel Tank Dry Bay Fuel Tank Dry Bay

Projectile Shotline Projectile Shotline

Powder Panel

Powder Panel

Figure 1-1. Typical Powder Panel Arrangements 

The design and acceptability criteria for these devices are different from conventional 

active fluid suppressant systems. Powder panels add weight based upon the surface area of the 

fuel wall/fire zone interface, as opposed to the volume of the fire zone, so the relative benefit of 

the panels is dependent upon the configuration of the particular bay. Typical areal densities 

(weight/surface area) for commercial powder panels are on the order of 0.195 to 0.244 g/cm2 (0.4 

to 0.5 lb/ft.2). 

Powder panels are not a new concept for extinguishing ballistic threat-induced fires in 

aircraft, as discussed previously. They have in fact been around for many years. Despite testing 

which has demonstrated the effectiveness of these devices, powder panels have seen limited use 

in aircraft and armored ground vehicles. Powder panels around aircraft fuel tanks were first 

developed and used by the Royal Aircraft Establishment in England. Some U.S. helicopters and 

the V-22 aircraft have implemented powder panels in their vulnerability reduction designs. 
3

Powder panels have also been widely examined for military combat land vehicles, such as tanks 

and armored personnel carriers, but have been applied in limited circumstances. 

Several reasons exist for the limited use of powder panels. False discharges do not occur 

with these passive fire protection devices, but cleanup following a fire or inadvertent damage has 

been a concern. This concern, primarily in aircraft, stems from the possibility of corrosion by 

the contact of chemical powders with vehicle structure. As a result, current powder panels often 

use an inert fire extinguishing powder, such as aluminum oxide (Al2O3), to prevent reaction with 

the metal. In military ground vehicles, wide application of powder panels has been limited due 

to the potential ill, albeit limited, effects on crewmembers or obscuration of the crew 

compartment upon activation. Although non-toxic agents can be used, during the period of time 

the powder particles are suspended in crew areas, the crew may have difficulty breathing and 

operational effectiveness may be limited. Several other reasons cited for their limited use overall 

include concerns over durability, potential adverse effects on electromechanical components and 

optics, their ability to protect highly cluttered areas, airflow influences, a lack of protection from 

accidental fires, and difficulty in selling a low-tech approach. 

Although powder panels have been examined for years, current commercial powder panel 

designs are in essence very similar to those that have existed for decades. However, a number of 

factors have renewed interest in powder panel technology. First, the banned production of halon 

1301, due to its ozone depleting potential, has created a demand for new techniques to fill its 

role. Also, new materials, powders, and construction techniques have been developed, which 

may allow for improved powder panel performance (both system weight and fire extinguishing 

capability). 

Since the production of halon 1301 has been phased out, systems that have used it for 

ballistic threat-induced fire protection in fire zones eventually will require some substitute 

technique. Powder panel technologies are viable alternatives for some of these applications. 

They don’t require detectors, plumbing, wiring or bottles, and they are false-discharge resistant. 

Current designs have limitations, particularly limited powder dispersion ability, and problems 

providing protection against relatively small caliber threats. As a result, most don’t compare 

favorably against halon 1301 in trade-off studies. 

Improved powder panels could expand use of this fire protection technology for 

additional vulnerable fire zones on our critical weapons systems. New powder panel concepts 

with enhanced characteristics have been proposed recently. These include frangible materials to 

optimize dispersion, single-piece construction technology, modular designs, predosed sections, 

lighter weight materials, and lower cost materials. These enhanced powder panels could be used 

in applications as halon 1301 or other fire extinguishing system replacements, or they could 

replace existing powder panels with superior technology. 

1.2 Fire Ignition and Powder Panel Effectiveness 

Powder panels work through the release of fire extinguishing powder into the mixing 

zone of a flammable fluid and an ignition source to essentially inert the zone or prevent a fire 
4

from igniting. To assist in the discussion of powder panels and their effectiveness, it is helpful to 

discuss fire ignition, as it relates to an onboard aircraft fire due to ballistic projectile penetration. 

For any fire to initiate, the interaction of a flammable fluid, oxidant, and ignition source 

is required (Reference 4). However, the simple mixing of these three ingredients does not ensure 

fluid ignition or the initiation of a sustained fire. Fire initiation by a ballistic threat is a complex 

phenomenon involving a process that sequentially brings together the three ingredients at the 

right time, in sufficient and proportional quantities, and with the needed intensity. The process 

begins when the ballistic threat penetrates the vehicle, functions its incendiary, and traverses the 

vehicle penetrating the fluid container, thereby releasing fluid into the open volume of the 

vehicle. This open volume is referred to as a dry bay in aircraft. While each threat type is 

inherently different, the result is the same, i.e., deposition of thermal energy into a volume of air 

in front of the impact hole and the raising of the temperature of this volume. If the threat impacts 

a flammable fluid container within the vehicle and releases fluid, the fluid will be injected into 

the dry bay some distance by the threat/container impact and the container pressure. As the fluid 

is injected into the dry bay, it atomizes (i.e., breaks up into droplets). As the droplets penetrate 

into the heated air, they begin to vaporize, and the fluid vapor mixes with the surrounding air and 

produces a flammable fluid/air mixture. As the fluid/air mixture is heated, a chemical reaction 

will commence. 

As the reaction proceeds, heat is lost to the surrounding air by conduction. If the rate of 

heat produced by the reaction exceeds the rate of heat lost by conduction, the chemical reaction 

will accelerate until all the oxygen (for fuel rich conditions) within this volume is consumed, a 

flash is seen more or less simultaneously throughout this volume, and ignition has occurred. If 

the rate of heat lost exceeds the rate of heat produced, then the temperature of the volume will 

begin to decrease, and the rate of reaction will decline as well. Eventually the reaction will cease 

and ignition will not occur. As such, ignition is simply a reaction that proceeds to consume the 

available flammable fluid/air mixture contained within the volume encompassed by the ignition 

source, resulting in a flame visible within this volume. If after ignition occurs, sufficient oxygen 

and the flammable fluid source are available, a sustained fire may result that could lead to a loss 

of the aircraft. 

Fire extinguishing powder introduced into this volume immediately upon impact by the 

ballistic projectile has the potential to reduce the probability of a fire ignition. The powder must 

render the fuel/air mixture nonflammable so the chemical reaction does not continue. The 

powder can do this in two ways. According to Reference 5 (and further citations in this 

reference), it is widely believed that fire extinguishing powders can function as both energyabsorbing materials and as solid surfaces on which free radicals can be destroyed. Heat may be 

absorbed by the heat capacity of the solid, the heat of fusion at the melting point, the heat 

capacity of the liquid, heat of dissociation from breaking of chemical bonds, and heat of 

vaporization. These all contribute to the total energy absorbing capability (endothermicity) of 

the fire extinguishing powder (Reference 6). 

From a chemical aspect, it has been found that there is a catalytic path for destruction of 

free radicals in certain fire extinguishing powders, for example, H, O, and OH, by utilizing the 

potassium in potassium salts (References 7, 8). Potassium salts have been shown to be more 
5

effective than sodium salts, and iodide anions are more effective than chloride anions. Any 

powder that has a chemical fire extinguishing capability will also have the heat-absorbing 

(endothermic) capability (Reference 9). 

Testing has shown that smaller and more numerous powder particles, through the 

increased surface area available, are more effective at reducing the chance of fire ignition than 

fewer, but larger particles (Reference 10). Reference 6 has shown that less weight of salt per 

unit volume of fuel-air mixture is required for extinguishment, if the salt is finely divided. Large 

particles may actually pass through the flame zone before they can reach flame temperature, and 

thus not absorb as much heat as an equivalent mass of finer particles. In other words, the time 

required for small particles to become effective is less than that for large particles. Thus, 

micrometer-sized solids are more efficient as fire extinguishing powders than are larger particles. 

Large surface areas are important in both the heat absorption and the chemical interference 

mechanisms. 

The effectiveness of the powder panel can, therefore, be enhanced through the proper use 

of a fire extinguishing powder (type and particle size), and by maximizing the amount of powder 

released into the mixing zone consisting of the flammable fluid and the ignition source. The 

objective of the enhanced powder panels is to appropriately select a powder and maximize the 

amount of powder released into the mixing zone. 
6

2. Task Objectives 

The objective of this project was to identify concepts for powder panel enhancement 

(relative to current capability and halon 1301) and demonstrate proofs-of-concept. The basis for 

this advanced protection consisted of characterization of current powder panel technology and 

assessment of recently developed improvements in powder panel materials and construction. 

The expected outcome of this work was enhanced powder panel concepts that are competitive 

with halon 1301 in critical parameters such as weight, volume occupied, fire extinguishing 

capability, etc. and, thus, are candidates for use in its place. 

3. Technical Problems 

In order to become a viable concept for combat fire protection in aircraft, two major 

technical problems for powder panels needed to be addressed. These two major problems, 

performance and practicality, are intertwined. Previous powder panel testing evaluated a number 

of different powder panel designs and materials and showed limited ranges of effectiveness. One 

consistent factor in many of these designs was the use of a honeycomb structural material as the 

rib or core material. Honeycomb provides several positive attributes to powder panels. First, it 

adds structural integrity to the panel, as honeycomb has proven to be as a structural design 

technique in aircraft construction. Honeycomb also allows for even distribution of the fire 

extinguishing powder throughout the panel, minimizing concerns over powder settling. It also 

can be constructed of very lightweight materials such as Nomex or aramid fibers. The limiting 

factor for honeycomb has been its performance. Only cells in the direct path of projectile 

penetration, and perhaps those just around the penetration area, are torn and allow powder to 

escape. 

 Different faces for the powder panel have been tested, focusing on materials such as 

aluminum foil and several different composites. Many of these efforts have focused on 

durability in the aircraft environment. However, performance, as quantified through surface area 

removal or fracturing, has been limited. This is true despite techniques to enhance opening of 

the powder panel walls such as weak or selective bonding of the panels to the core, particularly 

for the front or open face to the fire zone. Very thin sheets or films have also been tried to 

promote surface removal and allow powder to escape. 

Consequently, this project needed to demonstrate the feasibility of completely redesigning a powder panel so that it could release a more effective amount of powder. However, 

production and qualification requirements levied on fire protection methods, such as powder 

panels, might show these designs to be impractical for aircraft applications. Therefore, 

additional work was required to optimize these panels for attaining potential design 

requirements. For example, with aircraft weight restrictions being very demanding, powder 

panel weight needs to be minimized before it can even be considered competitive as a fire 

protection solution for a particular aircraft application. This goal involves proper material 

selection and powder panel thickness determinations. Another key aircraft requirement is 

durability in the aircraft’s harsh operating environment. This includes an ability to survive under 
7

extreme (both hot and cold) temperature, vibration, g-loading, and exposure to a variety of 

chemicals (jet fuel, hydraulic fluid, etc.). These environmental restrictions further reduce the set 

of materials and design concepts that can be used. Other production requirements may be related 

to such items as maintainability and reliability. Thus, the problem becomes one of developing a 

powder panel that is competitive with other fire extinguishing technologies by releasing 

sufficient powder when penetrated by a ballistic projectile to prevent fire ignition, while still 

remaining acceptable under tightly controlled aircraft environment requirements. 

4. General Methodology 

NGP research into enhanced powder panels was organized into two phases. In the first 

phase, background information was gathered on the state-of-the art of current powder panels, 

initial concepts for enhanced powder panels were examined, and the feasibility of improved 

powder panel features was demonstrated. In Phase II, the examination was widened to study if 

enhanced powder panels were not only feasible, but could become practical, while maintaining 

improved performance. Optimized powder panels were examined for their potential to meet 

production requirements and their benefits were examined against other fire protection 

alternatives. The program concluded with final live fire demonstration tests of the optimized 

powder panels. 

4.1 Powder Panel and Application Survey 

Efforts on this project began with a survey of powder panel applications in operational 

U.S. aircraft and investigations of previous powder panel testing. The purpose of the survey was 

to identify powder panel materials and designs that have been previously evaluated and those 

that have actually been integrated into aircraft designs. Using this information as a baseline, it 

was then possible to explore potential improvements in powder panel designs. 

Powder panels around aircraft fuel tanks were first developed and used by the Royal 

Aircraft Establishment in England (Reference 11). They have also been examined widely for 

military combat land vehicles, such as tanks and armored personnel carriers (References 12, 13, 

14, 15), compared to aircraft applications. The powder panel survey conducted in this program 

included the collection of all available data; however, it focused on more recent test programs 

and on testing related to U.S. aircraft applications. 

An example of the integration of powder panels into a U.S. aircraft design is the use of 

these fire extinguishing devices in the V-22 Osprey. However, the widest use of powder panels 

has been in helicopters. A number of test programs have been conducted to evaluate powder 

panel applications in helicopters. A significant effort was conducted, for example, to evaluate 

both parasitic (attached to existing structure) and structural (panels themselves function as 

structure) powder panels in Army AH-1S Cobra helicopters (References 11, 16, 17, 18). 

Although powder panels were never integrated into the AH-1S, they did find their way into the 

Navy UH-1Y Huey and AH-1W Super Cobra (Reference 19). AH-1W and UH-1N legacy 

aircraft are being upgraded to the AH-1Z Super Cobra, which uses powder panels for dry bay 
8

protection. Testing was recently conducted at Boeing to evaluate powder panel applications in 

the AH-64 Apache. This evaluation examined the use of powder panels along various fuel tank 

walls. Powder panels have also been evaluated recently for the RAH-66 Comanche helicopter. 

The powder panel application survey indicated no U.S. fixed wing aircraft currently 

employ powder panels. A number of reasons have been offered for the lack of implementation 

of powder panels in fixed wing aircraft. Among these reasons are that powder panels do not 

assist with accidental fires; low-tech approaches are difficult to sell; and there are concerns over 

accidental leakage that could lead to corrosion, durability, volume-filling capability with clutter 

involved, and detrimental airflow influences. 

Despite the resistance to implementing powder panels, the success of Phase I evaluations 

of enhanced powder panel designs sparked interest by several aircraft programs. The potential 

for increasing effectiveness without negatively impacting weight and other concerns has 

generated renewed interest. Among the programs inquiring about enhanced powder panel 

development are the F-35 Joint Strike Fighter, CH-53E Super Sea Stallion, RAH-66 Comanche, 

and the V-22 Osprey. In the midst of these discussions, Skyward entered into proprietary rights 

agreements with Bell Helicopter Textron, Inc./The Boeing Company and Sikorsky Aircraft 

Corporation/The Boeing Company to discuss the possibility of integrating enhanced powder 

panels into aircraft such as the V-22 and RAH-66, for example. These proprietary rights 

agreements allowed for the free exchange of design details and production or qualification 

requirements that may be levied on newly developed panels. 

The survey conducted in this NGP project included an examination of previous powder 

panel test programs relating to U.S. applications extending back to at least the late 1970’s 

(Reference 16). Many of the test programs included evaluations of the fire extinguishing 

effectiveness of various powder panel designs and various dry powders contained within the 

panels (References 3, 20, 21). Standard designs included the use of thin aluminum foil, Nomex, 

or composite panels sandwiching an aluminum or Nomex honeycomb core, which contained the 

fire extinguishing powder. Typical powders included aluminum oxide (Al2O3), Purple K 

(KHCO3), and Monnex (KC2N2H3O3) for example. Al2O3 has been extensively used in powder 

panel testing and is the only powder identified in U.S. aircraft applications, primarily due to its 

low corrosiveness compared to the other powders (References 13, 5). A summary of some 

previously tested powder panel materials is included in Table 4-1. 
9

Table 4-1. Examples Of Previously Tested Powder Panel Materials 

FRONT FACE RIB 

STRUCTURE 

BACK FACE PANEL 

THICKNESS 

(mm) 

POWDER 

• 0.0254 mm (0.001") 

8111-0 aluminum (Al) 

alloy foil 

• 0.102 mm (0.004”) Al 

• 0.508 mm (0.020") 

2024-T3 Al 

• 0.0254 mm (0.001”) 

stainless steel 

• 5.08 mm (0.20") 

titanium 

• 2-ply graphite-epoxy 

tape 

• 3-ply (0/90/0) graphite 

epoxy 

• 2-ply Kevlar-epoxy 

cloth 

• polyethylene 

• Pro-Seal coated ballistic 

nylon bags 

• 2024-T2 Al 

honeycomb 

• fiberglass 

honeycomb 

• Al foil bags 

• Nomex 

honeycomb 

• 0.001" 8111-0 alloy 

Al foil 

• 0.330 mm (0.013”) 

Al 

• 0.508 mm (0.020") 

2024-T3 Al 

• 4.06 mm (0.16") 

2024-T3 Al 

• 2-ply fiberglass/ 

epoxy 

• 2-ply graphite/ 

epoxy tape 

• 3-ply (0/90/0) 

graphite/epoxy 

• 2-ply Kevlar/epoxy 

cloth 

• polyethylene 

• Pro-Seal coated 

nylon 

• 1.27 

• 1.78 

• 2.29 

• 2.54 

• 3.0 

• 3.05 

• 6.4 

• 9.5 

• 12.7 

• 25.4 

• Monnex 

• KDKI 

• Al2O3

• Al2O3+10% 

KI 

• Al2O3 with 

1% silicon 

oxide 

• Purple K 

• potassium 

bicarbonate 

• 10% acetate 

in water 

 The literature review revealed some unique powder panel designs and configurations 

evaluated in previous testing (Reference 22, 23), but also more common powder panel materials 

and designs. Very thin aluminum or aluminum foil and composite materials have most often 

been evaluated for the front face or the face toward an open dry bay. Similar materials have 

been evaluated for the back face or the face attached to or directly adjacent to the flammable 

fluid container. As Table 4-1 indicates and the literature search showed, the most common rib 

structural design by far evaluated in previous powder panel testing has been honeycomb. The 

honeycomb has been composed of various materials, but it has most often been evaluated to 

enable even distribution of powder and for structural rigidity of the panel. 

In addition to examining military-specific powder panel testing, an examination of recent 

powder panel work for non-ballistic applications was performed. Data were obtained for powder 

panel evaluations using a much wider variety of materials with potential for greater fire 

extinguishing effectiveness. A limited license agreement was established with Horizons 

Unlimited to examine some recent powder panel design concepts and allow for evaluation of a 

patented design concept. Drawing upon data from the powder panel survey and this agreement, 

a baseline set of materials and designs was established for examination in the first phase of this 

project. 

The second phase of the NGP project involved an expanded survey and investigation that 

included the identification of aircraft using active halon systems for fire protection, particularly 

in areas where powder panels could be used. This research was to be used for later comparisons 

of potential powder panel fire protection systems with current halon systems (Section 4.5). The 
10

expanded survey also included the identification of design issues for integrating enhanced 

powder panels into production aircraft and the identification of any necessary qualification 

testing required before implementation. 

The examination of aircraft fire protection systems in the expanded survey revealed halon 

systems are infrequently used in dry bay areas (Reference 24). Conversely, powder panels have 

been demonstrated to be effective almost exclusively in these areas. Active halon fire 

extinguishing systems are prevalent in engine nacelles or auxiliary power unit compartments for 

fire protection (e.g., A-10, B-2, C-12, C-130, F-14, F-22, P-3 and many other aircraft) or for 

inerting in fuel tank ullage areas to protect against ullage explosion (e.g., A-6, F-16, and F-117). 

Powder panels have typically been evaluated in aircraft dry bay areas and have only been 

integrated into production aircraft in these areas (e.g., V-22 and AH-1W). Therefore, as a part of 

the cost-benefit or return-on-investment analysis discussed in Section 4.5, a direct comparison of 

an existing halon fire extinguishing system with an enhanced powder panel system proved to be 

difficult. 

There are only a few potential examples of halon fire protection systems that could 

provide direct comparisons for a dry bay area. Most of these examples, however, do not offer 

likely replacement possibilities and are not applicable across a wide range of aircraft. For 

example, the C-5 aircraft has a center wing leading edge dry bay, which is protected by a halon 

fire extinguishing system. However, this system was incorporated to protect against overheat or 

safety-related fires from hydraulic components, not ballistic impact. It is located above the 

fuselage and would be difficult to hit for most reasonable combat scenarios. Replacement with a 

passive powder panel fire protection system may not prove practical in this case. As in this 

example, some of the current halon systems are focused on protecting flammable fluid lines or 

electronics, which has not been a focus for integrated powder panels, thus far. The C-5 has two 

other dry bay-type areas with halon protection, focusing on electronics protection, not flammable 

fluid container protection. The B-1 also has an overwing fairing protection system, meant for 

protection of a hydraulic line and fuel line. It is not an ideal area for comparison with powder 

panels, either, for the same reasons discussed for the C-5 aircraft. Data were gathered during this 

survey for other aircraft areas that provide a more practical application for enhanced powder 

panels. 

Discussions were held during the course of the NGP survey with various aircraft 

manufacturers to examine production design requirements or issues, and to provide data to them, 

which could allow for the consideration of enhanced powder panels in design trade studies. 

Discussions were held with Bell Helicopter - Textron, Inc., The Boeing Company, Sikorsky 

Aircraft Corporation, and Lockheed Martin Corporation. Specific aircraft discussed were the 

V-22, RAH-66, and F-35. As discussed previously, proprietary rights agreements were 

established with Bell/Boeing and Sikorsky/Boeing, and an existing agreement was in place 

between Skyward, Ltd. and Lockheed Martin. The proprietary agreements allowed for the free 

exchange of design details and production or qualification requirements that may be levied on 

newly developed panels. 

 Specific production aircraft requirements were considered proprietary in most cases, but 

general design requirements were not and are notable. Among the key design criteria often 
11

mentioned in the discussions were powder panel thickness, areal density (weight per unit area), 

and temperature environment. As with any other aircraft component, particularly a forward-fit 

component, size and weight are big factors. The powder panel must not interfere with existing 

equipment and cannot create a significant weight penalty. Since design values associated with 

specific military aircraft are part of the technical specifications for the respective aircraft, these 

values will not be discussed herein. 

However, these values along with current commercial powder panel thicknesses and 

weights were used as design goals for the Phase II optimization effort. Commercial powder 

panels used for testing were composed of a thickness over 0.254 cm (0.1 in.). The core was 

composed of a honeycomb design and the face sheets were constructed of a composite material. 

These panels had an areal density of around 0.2 g/cm2 (0.4 lbs/ft.2). In repeated conversations 

with aircraft manufacturers, the temperature range most often quoted as a potential extreme 

requirement for powder panels was from -40°C to 104°C (-40°F to 220°F). In many aircraft 

areas, continuous service temperature would not reach these extremes, but for purposes of the 

optimization design effort, these temperatures were considered important. 

The aircraft prime contractors were also asked if enhanced powder panels would have to 

undergo any qualification tests such as thermal cycling, impact resistance, vibration or other 

durability testing, chemical resistance examinations, and moisture absorption evaluations, for 

example. Based upon their responses, data suggest that commercially available powder panels 

may have used individual material data to support such qualification, but the assembled powder 

panels did not appear to be subjected to many of these tests for production qualification. This is 

not to imply that future powder panel applications may be relieved of such requirements. Some 

limited production design criteria were considered for the fully assembled enhanced powder 

panel, such as panel thickness, areal density (weight per unit area), and temperature environment, 

as mentioned above. However, resources in this program did not permit a full examination of 

many of these other potential production requirements. 

4.2 Impact Dynamics Experiments 

Phase I experimental testing with enhanced powder panels began in the fall of 2001. An 

experimental test device (dry bay/fuel tank simulator) was designed and fabricated to enable a 

direct comparison of powder panel materials and designs, both existing and improved concepts. 

Through an impact dynamics study, various characteristics critical to the fire extinguishing 

effectiveness of powder panels were examined. The test device shown in Figure 4-1 allowed for 

the experimental screening of candidate powder panels by comparing these characteristics in a 

highly repeatable fashion. Among the characteristics examined were panel impact dynamics, 

including cracking and material removal, the amount of fire extinguishing powder released into 

the test article, the dispersion of this powder, and the time the powder remained suspended in the 

dry bay. 
12

Fuel Tank

(1 ft3)

Dry Bay

(2 ft3)

Powder

Panel

Shotline

Shotline

Powder

Collection Cups

Witness Rods Powder Panel

Figure 4-1. Experimental Test Device and Powder Collection Methods 

The test device simulates a 0.057 m3

 (2 ft.3) aircraft dry bay and a 0.028 m3 (1 ft.3) fuel 

tank. The fuel tank is capable of holding fluid, and the dry bay is designed with Lexan windows 

to allow for visual observation of each test. Testing in the first phase did not involve fluid in the 

tank, or airflow, so the screening process would be simplified. Replaceable 7075-T6 aluminum 

panels of 2.032 mm (0.08 in.) thickness were inserted to represent the fuel tank wall adjacent to 

the dry bay. In most of the tests, powder panels were secured directly in front of the fuel tank 

wall. This offered the worst-case scenario, without fluid in the tank, for evaluating the amount 

of powder released into the dry bay. The test device also allowed for the installation of powder 

panels directly behind the dry bay wall where the projectile enters the test article. 

The test device was designed to capture powder dispersion information so a direct 

comparison between candidate powder panels could be made. Figure 4-2 (right side) shows the 

powder collection methods used in the dry bay. Witness rods are located throughout the dry bay. 

Plastic tubes are slid over the rods to capture released powder during each test. The rods are 

placed in a pattern to ensure that the powder dispersion characteristics throughout the dry bay are 

understood. The plastic tubes are qualitatively examined for signs of powder after each test. 

Powder collection cups are also located in the dry bay. These cups are located along the 

shotline, where the powder concentration is most important during a ballistic projectile impact. 

The path of the projectile incendiary or impact flash is the location where the mixture of 

flammable fluid and ignition source is most likely to result in fire initiation. The collection cups 

were examined and weighed after each test to determine the amount of powder collected. In 

addition to these collection methods, each panel was weighed before and after each test to 

determine the amount of powder released. Panel components were also individually weighed to 

assist in determining the mass of powder loaded into each panel. The removed area of the front 

face (dry bay side) of the powder panel was also determined. This area was typically a direct 

correlation with the amount of powder released into the dry bay and provided another measure to 

compare the panels. The back face (fuel tank side) removed area of the powder panel was also 

determined for comparison with the front face and to examine the influence of one upon the 

other. Digital video was captured for each test to assist in determining characteristics related to 

powder suspension and dispersion. 
13

Experimental testing was conducted at the Air Force 46th Test Wing Aerospace 

Survivability and Safety Flight’s Aerospace Vehicle Survivability Facility (AVSF) at WrightPatterson Air Force Base (WPAFB), Ohio (Figure 4-2). The Aerospace Survivability and Safety 

Flight (46 OG/OGM/OL-AC) was the managing laboratory for this NGP work. In Range A of 

this facility, a light-gas gun (compressed helium-filled bottle rated at 20.68 MPa (3,000 psi)) was 

used to launch 0.50 caliber hard steel ball projectiles at velocities of approximately 671 

meters/second (2,200 feet per second). The kinetic energy of these projectiles was roughly 

equivalent to a threat greater than a 7.62mm armor piercing incendiary (API), but just less than a 

12.7mm API projectile. 

Figure 4-2. AVSF Range A Light-Gas Gun 

Testing during Phase I involved only one dry chemical fire extinguishing agent. The 

powder selected was Purple K (KHCO3) due to its non-toxic nature, visibility for post-test 

inspection, and fire extinguishing effectiveness. Corrosion from long-term exposure was not a 

concern in these tests. 

4.3 Live Fire Proof-Of-Concept Demonstrations 

During the summer of 2002, following Phase I experimental testing, Skyward, Ltd. was 

afforded the opportunity to participate in several live fire demonstration tests of enhanced 

powder panels. These proof-of-concept tests were conducted in two different test series 

simulating aircraft dry bays and involving the potential ignition of a fuel fire. These tests 

provided Skyward with an opportunity to select some of the more effective enhanced powder 
14

panel design features identified in Phase I, perform some quick optimization, add some unique 

design features not previously evaluated, and perform live fire testing, all in advance of the 

initiation of Phase II. The promising results of these demonstration tests provided a leap forward 

for the initiation of Phase II. 

4.3.1 JTCG/AS Demonstration Testing 

The ability of enhanced powder panels to prevent fire ignition was first demonstrated in a 

Joint Technical Coordinating Group on Aircraft Survivability (JTCG/AS), since renamed Joint 

Aircraft Survivability Program Office (JASPO) test program examining reactive powder panel 

concepts, which is a method of using a reactive energetic backing with any powder panel design 

to enhance powder delivery effectiveness (Reference 25). These tests were conducted at the 

Naval Air Warfare Center-Weapons Division Weapons Survivability Laboratory in China Lake, 

California. Four tests of enhanced powder panels without reactive backing were conducted. 

These tests involved the firing of 12.7mm API projectiles into a dry bay/fuel tank simulator 

containing JP-8 fuel. Projectiles were fired at approximately 757 m/s (2,500 ft./s) at a 0°

obliquity angle into the dry bay, impacting an aluminum striker plate, which was separated from 

the powder panel/fuel tank by approximately 0.305 m (1 ft.). The projectiles functioned upon 

impact of the striker plate and then continued through the powder panel, penetrating the fuel tank 

and releasing JP-8 fuel. A 0.46 m wide x 0.61 m high x 1.22 m long (1.5 ft. x. 2 ft. x 4 ft.) dry 

bay (right side of Figure 4-3) was connected to a 1.22 m x 1.22 m x 1.22 m (2 ft. x 2 ft. x 2 ft.) 

fuel tank (left side of Figure 4-3). A 3.175 mm (0.125 in.) 2024-T3 simulated fuel tank bulkhead 

was positioned on the front or initial impact side of the fuel tank. The powder panel was 

attached to this removable bulkhead panel with a 2-part epoxy adhesive. Tests were also 

conducted with commercial powder panels in this test series to provide a basis of comparison 

with the enhanced powder panel tests, as well as to tests with no protection. 

Figure 4-3. JTCG/AS Test Article Setup 

Fuel Tank 

Dry Bay 
15

4.3.2 FAA Demonstration Testing 

A second demonstration test series of an enhanced powder panel was conducted in a 

Federal Aviation Administration (FAA) program (Reference 26). This test series was also 

conducted at China Lake, just after the JTCG/AS series. This test examined the feasibility of 

powder panels in preventing fuselage fires in commercial aircraft caused by the release and 

impact of an uncontained engine rotor blade with flammable fluid lines. Figure 4-4 shows a 

schematic of the test article. A simulated rotor blade was fired through the lower bay and into 

the luggage compartment and an ignitor initiated a fire in the presence of leaking fuel as the rotor 

blade penetrated the lower bay. An enhanced powder panel successfully prevented a fire from 

igniting in one of the tests. A second test was invalidated due to problems with the timing 

sequence, but unrelated to the powder panel. Two commercial powder panel tests were also 

conducted during this test series to evaluate their effectiveness and allow comparison of the 

results with those of the enhanced powder panel test. 

Figure 4-4. FAA Test Article Schematic 

4.4 Parametric/Optimization Experiments 

In Phase II, Skyward continued their impact dynamics research, with a focus on 

optimizing the enhanced powder panels, parametrically examining design variations, and then 

demonstrating the optimized panels. Panel materials, thickness, and construction techniques 

were optimized to reduce the panel weight and thickness, while maintaining effective powder 

release and dispersion. 

Luggage Compartment 

Lower Bay Containing 

Flammable Fluid Lines 

Cabin Area 
16

Testing was conducted in the same simulated dry bay experimental device used for 

concept evaluations in Phase I, and with the same light gas gun launching 12.7mm (0.50 in.) 

diameter ball projectiles. Optimization test variables included panel materials and thicknesses, 

fire extinguishing powder loading (density of powder inserted into a given panel size), rib 

designs, and the assembly process. Optimization testing focused on the three primary areas of 

investigation outlined below: 

• effectiveness optimization (maximize front face fracture and powder release), 

• practicality enhancement (reduce weight, decrease panel thickness, address production 

issues), 

• and reliability improvement (quantify reliability of measures of effectiveness, increase 

durability, and reduce risk of accidental leakage). 

Maximizing powder release into the dry bay continued to be the defining goal, but other 

requirements were levied on the design effort to ensure the enhanced powder panels were as 

practical and reliable as possible. Weight was reduced, panel thickness was minimized, and 

other potential production requirements were considered. An areal density (weight per unit area) 

target was provided by one of the vehicle manufacturers for the design effort. 

Phase II testing primarily involved the use of aluminum oxide (Al2O3) over Purple K 

(KHCO3) or other powders, even though these other powders have been demonstrated to be more 

effective as fire extinguishing agents. At least two of the aircraft manufacturers in the powder 

panel survey expressed doubt that any potentially corrosive chemical powder would be 

acceptable by their aircraft, so there was a conscious effort made to demonstrate the 

effectiveness of Al2O3 during the optimization testing. Al2O3 is the only known powder panel 

agent to be incorporated into an aircraft due to its lack of reactivity with aircraft structure. 

Additionally, since Al2O3 has a much higher specific gravity than KHCO3 (3.95 compared to 

0.88), it was thought to be worst-case and would help with determining success in weight 

reduction efforts. The Al2O3 tested was 5 μm in average size compared to an average of 

approximately 30 μm for the KHCO3, which may also mean it could pack more tightly. 

Certain front face materials evaluated in Phase I testing proved to be effective and 

remained a focus in Phase II. These materials included thermoplastics with brittle material 

properties and some thermoset resins. Other unique materials were also examined that more 

appropriately targeted optimization requirements. Efforts were made to minimize front face and 

overall thickness and yet maintain sufficient strength to avoid accidental fracture. Lower density 

materials were examined and compared to more dense materials. 

Various new and unique designs were examined for the rib structure in Phase II, 

including the thickness of the ribs and attachment methods to the front and back faces. Since the 

license agreement with Horizon’s Unlimited expired at the end of Phase I testing, several options 

were eliminated from examination to avoid the potential for data rights infringement. The rib 

design was examined in detail because it directly affects the potential fire extinguishing powder 

loading, which can be the primary weight driver in the overall design. Various rib materials 

were examined for influence on powder panel performance, including some materials evaluated 

in the more effective Phase I designs. 
17

 Phase II testing also included examinations of back face materials and thicknesses and 

their influence on powder panel effectiveness. Materials examined in Phase I were once again 

tested along with some materials not previously evaluated. Testing included designs where the 

front and rear faces and the rib materials were the same and others where dissimilar materials 

were used. 

 Bonding techniques were also examined, with an emphasis on ensuring a robust overall 

design that reduced the risk of accidental leakage. In addition, rib-to-face bonding was examined 

for its influence on the performance of the powder panel. This influence was noted in Phase I 

testing and further examined in Phase II. Bonding materials were examined, as well as bonding 

patterns or techniques. 

4.5 Live Fire Demonstration Testing of Optimized Enhanced Powder Panels 

Phase I NGP experimental research into powder panel fire protection resulted in a 

demonstration of the feasibility of enhanced powder panels. As discussed in the preceding 

sections, unplanned, target-of-opportunity proof-of-concept live fire testing demonstrated these 

designs could prevent fire ignition. Phase II research then concentrated on optimizing these 

designs. At the end of Phase II, a series of live fire demonstration tests was conducted of the 

optimized designs. These tests were conducted to demonstrate the most promising enhanced 

powder panel designs could prevent fire ignition and be competitive with commercial powder 

panels in vital design criteria such as weight and thickness. These tests also demonstrated that 

powder dispersion and fracture mechanics results shown in the small experimental test article 

could be extrapolated to a larger, more realistic test article. These tests also examined 

attachment techniques for the powder panels, the effectiveness of Al2O3, historically the 

preferred dry chemical powder in aircraft applications, and the effect of certain variables on 

enhanced powder panel effectiveness. These Phase II demonstration tests were the culmination 

of the NGP project. 

Phase II live fire demonstration testing was conducted by the Air Force 46th Test Wing 

Aerospace Survivability and Safety Flight, NGP’s managing laboratory for enhanced powder 

panel research. The tests were conducted in outdoor Range 2 at their Aerospace Vehicle 

Survivability Facility, Wright-Patterson Air Force Base, Ohio. Demonstration testing involved 

baseline testing to ensure a fire could be ignited when a powder panel was not present. One test 

was conducted with a standard commercial powder panel to evaluate its effectiveness for the 

same test variables. Finally, six enhanced powder panel tests were conducted. 

Testing involved a very similar setup to the JTCG/AS tests discussed in Section 4.4.1 

above. A simulated dry bay/fuel tank test article was used of a larger size than the experimental 

test device. The dry bay measured 0.61 m wide x 0.61 m high x 1.22 m long (2 ft. x 2 ft. x 4 ft.). 

The fuel tank attached to one end of the dry bay measured 0.36 m wide x 1.22 m high x 0.61 m 

long (1.17 ft. x 2 ft. x 1 ft.). The powder panels were connected to a simulated fuel tank wall 

composed of 1.803 mm (0.071 in.) thick 2024-T3 for most tests. A striker plate was located 

0.305 m (1 ft.) in front of the powder panel/fuel tank wall to ensure projectile functioning. 
18

Lexan panels in the test article allowed test results to be observed directly. The ballistic 

projectile selected for testing was a 12.7mm API fired at approximately 757 meters per second 

(2,500 ft./s). Instrumentation included a couple thermocouples for temperature measurement, a 

threat velocity detection system, and video coverage, including high-speed and real-time video. 

A detailed description of the optimized panel demonstration testing is summarized in the test 

plan presented in Appendix A. Figure 4-5 below shows the test article setup. 

Figure 4-5. Test Article Setup 

4.6 Return On Investment Predictions 

The potential for combat-related aircraft dry bay fire is a known vulnerability for many 

aircraft. However, the infrequent use of halon fire extinguishing systems in aircraft dry bays 

implies that cost, weight, maintenance, and/or performance parameters have not been sufficient 

to justify such a system for these areas. Other fire protection methods such as solid propellant 

gas generator systems, void space foam filler, or even commercial powder panels have been 

implemented in some cases, but many dry bay areas still go unprotected. It is possible that a 

more effective powder panel could offer a justifiable option for previously unprotected dry bay 

areas or a well-supported alternative to areas protected by other means. 

One of the tasks planned for this project was to perform a comparison of an enhanced 

powder panel protection system with a halon fire extinguishing system to demonstrate its 

potential as a halon alternative. The powder panel survey (Section 4.1) revealed it was very 

difficult to find a practical example for which to perform a direct comparison. In addition, 

obtaining design information for certain areas that might provide a comparison was very difficult 

within the resources of this program. To further complicate this task, when information was 

obtained on a potential aircraft area or an alternative system used in trade studies, the 

information was often considered proprietary and was not releasable. Therefore, an emphasis 

was placed on generating some estimates for integrating powder panels into forward-fit or 

currently unprotected areas. When possible, active system information was estimated for 

Fuel Tank Dry Bay 

Striker Plate

Powder Panel 
19

possible integration into the same areas. It turned out that the most practical comparisons were 

with current powder panels and other active fire extinguishing systems, such as solid propellant 

gas generators (SPGGs). 

Comparisons with halon fire extinguishing systems in engine nacelles or APU 

compartments were considered, but are not practical. Significant additional work would be 

necessary to demonstrate powder panels in such an area, where airflow and hot surface ignition 

are concerns, before the results of the comparison would be acceptable. Additionally, in these 

areas where safety fires are of an equal or greater concern than ballistic threat-induced fires, 

powder panel protection is not currently a consideration due to the passive nature of powder 

panels. This eliminated some potential comparisons on the C-5 and B-1 aircraft mentioned in 

Section 4.1, for example. 

 One forward-fit example explored was the C-130 Hercules aircraft. The C-130 outer 

wing leading edge is not currently protected by a fire extinguishing system. The wing is divided 

into two segments, the center wing section (CWS) and the outer wing section (OWS). Since the 

outer wing fuel tanks are vulnerable to enemy fire, have no fire protection, geometric data were 

available, and data were available for an estimated active fire extinguishing system, it was 

practical to use this example. 

A preliminary analysis was conducted for the OWS leading edge dry bays circa 1996 to 

estimate the weight of an SPGG fire extinguishing system using then off-the-shelf components. 

The weights were estimated for the wing leading edge dry bays between engines #1 and #2 and 

between #3 and #4 (referred to as inboard leading edge dry bay) and outboard of the #1 and #4 

engines (referred to as outboard leading edge dry bay). This analysis also included estimates for 

the engine area dry bays, but for purposes of this study, the comparison is limited to the leading 

edge dry bays. It was estimated one inboard leading edge dry bay would require about 1,070 g 

(2.36 lbs.) of agent and an outboard leading edge dry bay would require about 1,186 g (2.61 

lbs.). To provide this agent to each dry bay would require three 420 g (0.93 lb.) unit (maximum 

agent load) generators each. The weight for each unit is about 1,302 g (2.87 lbs.), for a total 

generator weight on one wing of 7,812 g (17.22 lbs.). One controller would weigh about 1,919 g 

(4.23 lbs.), which would be capable of controlling all the SPGGs in both wings. It is estimated 

both the inboard leading edge and the outboard leading edge would each require three optical 

sensors. Each sensor weighs approximately 177 g (0.39 lb.), for a total weight on one wing of 

1,062 g (2.34 lbs.). For purposes of this study, the cables and braces or mounting hardware 

required was arbitrarily assumed to weigh about 10% of the SPGG and sensor weight for each 

dry bay. This weight could be more significant, depending upon were the controller is located, 

etc., but should provide a slightly better estimate than ignoring this weight. 

Feasibility and demonstration testing of SPGGs was conducted in the C-130 

Vulnerability Reduction Program, as part of C-130J Live Fire Test & Evaluation, and determined 

that the weight of agent in the 1996 preliminary analysis was likely overestimated (Reference 

27). However, the estimates provided are the best available since a fully optimized system has 

not been examined. Table 4-2 provides weight estimates for each of the SPGG system 

components for the C-130 outer wing’s leading edge dry bays. 
20

Table 4-2. C-130 Wing Leading Edge Dry Bay Fire Extinguishing System Component 

Weight Estimates 

Description Inboard 

Leading 

Edge 

Outboard 

Leading 

Edge 

Volume 1.52 m3

(53.5 ft.3) 

1.68 m3

(59.3 ft.3) 

Area 2.73 m2

(29.4 ft.2

) 

3.43 m2

(36.9 ft.2

) 

SPGG Propellant Required 1,070 g 

(2.36 lbs.) 

1,186 g 

(2.61 lbs.) 

Number of SPGGs (420 g Units) 3 3 

SPGG Weight (3) 3,906 g 

(8.61 lbs.) 

3,906 g 

(8.61 lbs.) 

Number of Optical Sensors 3 3 

Optical Sensor Weight (3) 531 g 

(1.17 lbs.) 

531 g 

(1.17 lbs.) 

SPGG Controller Weight 1,919 g 

(4.23 lbs.) 

- 

Wiring, Brackets and Mounting Hardware 

(Estimate 10% of SPGG/Sensor Weight) 

443.7 g 

(0.98 lb) 

443.7 g 

(0.98 lb) 

Light Enhanced Powder Panel Weight - 

0.160 g/cm2 (0.327 lb/ft.2) 

4,368 g 

(9.63 lbs.) 

5,488 g 

(12.10 lbs.) 

Heavier Enhanced Powder Panel Weight - 

0.205 g/cm2 (0.420 lb/ft.2) 

5,597 g 

(12.34 lbs.) 

7,032 g 

(15.50 lbs.) 

Commercial Powder Panel Weight - 

0.192 g/cm2 (0.393 lb/ft.2) 

5,242 g 

(11.56 lbs.) 

6,586 g 

(14.52 lbs.) 

Adhesive Weight for Powder Panels 

(Estimate 10% of Heaviest Panel Weight) 

560 g 

(1.23 lbs.) 

703 g 

(1.55 lbs.) 

 Table 4-2 also provides estimates for enhanced powder panel fire protection systems. 

Estimates are shown for both a lower weight version (areal density of 0.160 g/cm2

) and a heavier 

version (0.205 g/cm2), both of which have been demonstrated to be effective in this program 

(Section 5.4). The lighter panel weighed 145.44 g (0.321 lb.) and the heavier panel weighed 

186.50 g (0.411 lb.). Areal densities for the commercial powder panels tested in this program 

ranged from 0.192 to 0.208 g/cm2

. An estimate using the lower weight 174.95 g (0.386 lb.) 

commercial powder panel is shown. An estimate is also provided for the weight of adhesive to 

attach either enhanced or commercial powder panels. 

Table 4-2 also shows estimated areas and volumes for the OWS wing leading edge dry 

bays. The SPGG agent requirements are estimated based upon volume, and, of course, the 

powder panel requirements are based upon wetted front spar area. Table 4-3 summarizes total 
21

weight estimates for each wing leading edge fire extinguishing system for an entire C-130 

aircraft (both wings). 

Table 4-3. C-130 Wing Leading Edge Dry Bay Total Fire Extinguishing System Weight 

Estimates 

Fire Extinguishing System Total System Weight 

Solid Propellant Gas Generator System Weight 23.4 kg 

(51.6 lbs.) 

Lighter Enhanced Powder Panel Design 1 

Weight - 0.160 g/cm2

 (0.327 lb/ft.2) 

22.2 kg 

(48.9 lbs.) 

Heavier Enhanced Powder Panel Design 2 

Weight - 0.205 g/cm2 (0.420 lb/ft.2) 

27.8 kg 

(61.3 lbs.) 

Commercial Powder Panel Weight - 0.192 

g/cm2

 (0.394 lb/ft.2) 

26.2 kg 

(57.8 lbs.) 

 The data show that enhanced powder panels can be very competitive with SPGGs in 

terms of weight for such a system. For this example, the 0.160 g/cm2 enhanced powder panel 

system would weigh about 1.2 kg (2.7 lbs.) less than the SPGG system for the entire aircraft. 

The lighter weight enhanced powder panel would obviously be a design objective, since for this 

application it could be as much as 5.6 kg (12.4 lbs.) lighter than its higher areal density 

counterpart. Future work will determine if further optimization is possible. The lighter 

commercial powder panel evaluated in this program was just under the weight of the heavier 

enhanced powder panel by 1.6 kg (3.5 lbs.). The powder panel weight was calculated, as if they 

were applied across the entire surface area of the leading edge spar. With external stiffeners 

located across the surface of the spar, it is likely modular powder panel sections would be 

inserted between stiffeners. This would further reduce powder panel weight. 

For a full analysis of this example, other issues such as cost and complexity would also 

need to be examined. Obviously, the powder panel systems should be relatively simple to apply 

and maintenance free once applied. The complexity of integrating an active fire extinguishing 

system would be more complicated and involve some power requirements, safety concerns, and 

perhaps integration issues with other systems. 

 Data were available for a second comparison of enhanced powder panels, in this case 

with a current gas generator system on the V-22 aircraft. The outboard tip rib dry bay on this 

aircraft has a volume of approximately 0.258 m3

 (9.1 ft.3). No airflow passes through this dry 

bay. Other relevant design details are part of the aircraft technical specifications and will not be 

described in detail. The active fire suppression system in this area consists of a 189 g (0.417 lb.) 

inert SPGG and a 283.5 g (0.625 lb.) sensor/detector. Testing was conducted on a larger inboard 

tip rib dry bay and this system was sized according to successful configurations in that area. The 

dry bay is monitored by a control box that currently monitors other areas of the aircraft, so no 

new weight was added for this equipment. Wiring and mounting hardware was added to the 

weight estimate, since this equipment is necessary specifically for this dry bay. The wiring 
22

would have to run to the control box in a central location. In the previous example, 

approximately 443.7 g (0.98 lb.) of weight was added for wiring and accessories. For this single 

generator and sensor, the weight for this estimate was reduced to 33% of this estimate or 147.9 g 

(0.326 lb.) for one wing, which is likely a favorable estimate. The total weight estimate for one 

wing would, therefore, be approximately 620.4 g (1.368 lbs.). 

 For comparison, weights for both enhanced powder panel designs discussed previously 

were estimated for this dry bay. The lighter weight powder panel, with an areal density of 0.160 

g/cm2 (0.327 lb/ft.2), would weigh about 713.6 g (1.573 lbs.) per wing. Incorporation of the 

heavier enhanced powder panel, with an areal density of 0.205 g/cm2 (0.420 lb/ft.2), would weigh 

about 914.3 g (2.016 lbs.). The commercial powder panel by contrast, with an areal density of 

0.192 g/cm2 (0.394 lb/ft.2), would weigh approximately 856.3 g (1.888 lbs.). Table 4-4 

summarizes these weight estimates. 

Table 4-4. V-22 Outboard Tip Rib Dry Bay Fire Extinguishing System Component Weight 

Estimates 

Description Outboard Tip Rib Dry Bay 

Solid Propellant Gas Generator Weight(1) 189 g 

(0.417 lb.) 

Sensor/Detector Weight(1) 283.5 g 

(0.625 lb.) 

Wiring, Brackets and Mounting Hardware 

Weight (Estimate 33% of Previous Example 

with 3 SPGGs) 

147.9 g 

(0.326 lb.) 

Lighter Enhanced Powder Panel Design 1 

Weight - 0.160 g/cm2

 (0.327 lb/ft.2) 

713.6 g 

(1.573 lbs.) 

Heavier Enhanced Powder Panel Design 2 

Weight - 0.205 g/cm2 (0.420 lb/ft.2) 

914.3 

(2.016 lbs.) 

Commercial Powder Panel Weight - 0.192 

g/cm2

 (0.394 lb/ft.2) 

856.3 g 

(1.888 lbs.) 

Adhesive Weight for Powder Panels (Estimate 

10% of Heaviest Panel Weight) 

91.4 g 

(0.201 lbs.) 

 Table 4-5 tabulates the total weight for the aircraft (both wings) for each of the fire 

protection systems. These data show the inert SPGG system for the total aircraft weighs about 

369 g (0.81 lb.) less than the lightest enhanced powder panel in this case. The commercial 

powder panel system would weigh about 285 g (0.63 lb.) more than this enhanced powder panel 

design or 654 g (1.44 lbs.) more than the SPGG system. The heavier enhanced powder panel 

design would weigh about 116 g (0.26 lb.) more than the commercial powder panel system. 

Obviously, one major difference in this example was the existence of a controller on the aircraft 

for the active system, which did not add weight. Although the differences in weight for this 

comparison are quite small, it is well known that aircraft weight increases carry large price tags. 

In this example, a judgment would need to be made based upon system cost and the savings in 
23

complexity, whether or not the weight increase for the enhanced powder panel system would be 

worthwhile. Further optimization of these enhanced powder panel designs in subsequent 

programs may further reduce the weight differences between this passive fire extinguishing 

system and this active fire extinguishing system. 

Table 4-5. V-22 Outboard Tip Rib Dry Bay Total Fire Extinguishing System Weight 

Estimates 

Fire Extinguishing System Total System Weight 

Solid Propellant Gas Generator System 1,241 g 

(2.74 lbs.) 

Lighter Enhanced Powder Panel Design 1 

Weight - 0.160 g/cm2 (0.327 lb/ft.2) 

1,610 g 

(3.55 lbs.) 

Heavier Enhanced Powder Panel Design 2 

Weight - 0.205 g/cm2 (0.420 lb/ft.2) 

2,011 

(4.43 lbs.) 

Commercial Powder Panel Weight - 0.192 

g/cm2

 (0.394 lb/ft.2) 

1,895 g 

(4.18 lbs.) 

 Many other comparisons are possible between the enhanced powder panels and other fire 

protection methods. However, the purpose of the examples provided above was to simply 

demonstrate that enhanced powder panels, which have been demonstrated in live fire tests to be 

effective, have also been optimized to levels that make consideration of this vulnerability 

reduction technique valuable. 
24

5. Technical Results 

The following sections describe the results of the various enhanced powder panel test 

programs discussed in Section 4 above. The experimental results of Phase I are described, 

followed by live fire proof-of-concept demonstration test results of the most promising postPhase I designs. Phase II experimental results are then described, as the enhanced powder panel 

designs were optimized. Finally, live fire demonstration test results are presented of the 

optimized powder panels. 

5.1 Impact Dynamics Experimental Results 

A total of 32 powder panel tests were conducted during the first phase of this program. 

These tests included components similar to those examined in previously tested powder panel 

programs to provide some baseline data. Among the materials tested were thin aluminum (0.406 

mm thick [0.016 in.]) and aluminum foil panels. Also examined were 3.175 mm (0.125 in.) and 

6.350 mm (0.25 in.) thicknesses of 5052 aluminum honeycomb, acting as the rib structure for 

various panels. A Nomex (aramid fiber paper) honeycomb core of 9.525 mm (0.375 in.) 

thickness was also tested. 

The majority of tests, however, featured unique materials and designs not evaluated in 

previous powder panel ballistic testing. Thermoplastic and thermoset materials were the focus of 

most testing. For the front panel face (dry bay side), materials that exhibited brittle properties 

upon impact, but durability in handling, were of utmost interest. The goal was to find a front 

face material and powder panel design that results in significant front face material loss and 

powder release into the dry bay during a ballistic impact event. Front face materials evaluated 

included a polycarbonate (Lexan), polystyrene, polypropylene, and polymethyl methacrylate 

(acrylic-Plexiglass). These materials are cost-effective and easily obtainable in off-the-shelf 

forms. For example, some off-the-shelf forms of these materials were panels used in overhead 

fluorescent light fixtures. These panels come in a variety of designs that may enhance or 

degrade their brittle nature. Both acrylic and polystyrene lighting panels in a variety of faceted 

designs were tested. The use of intentional surface scoring of flat acrylic panels was also 

examined using a couple of different scoring patterns and different techniques for implementing 

the scoring lines. The intent was to determine if surface scoring could be used to enhance the 

fracture characteristics of the material. 

Thermoset polymers were also evaluated for the front face. Tested materials included 

two polyester resins, an epoxy resin, and a thin epoxy primer. The thin epoxy primer tested was 

only 0.0762 mm (0.003 in.) thick. It is available commercially as a spray and requires a careful 

procedure for forming it and bonding it to the rib structure. The other thermoset materials are 

readily available in commercial form, requiring the mixing of a two-part liquid resin. 

Plastics were also tested for the back face (fuel tank wall side) and in various 

configurations for the internal rib structure of the panel. The impetus for experimenting with the 

back panel was to determine if the fracture characteristics of the back panel influence the front 
25

panel in any way. For the dry bay/fuel tank configuration examined, there was a desire to inhibit 

the back panel hole size to reduce flammable fluid leakage, which could assist in reducing fire 

ignition probability in an actual production configuration. 

A number of materials and designs were examined for the powder panel internal rib 

structure. The rib structure adds rigidity and strength to the panel, prevents settling of the 

powder, and must allow for easy release of as much powder as possible. Some of the panels 

examined in Phase I were single piece extruded materials that had front and back walls and 

internal channels. These panel designs were composed of polycarbonate and polypropylene. 

They were filled with powder in their production form, and the ends were sealed for testing. As 

mentioned, honeycomb materials were also examined. One honeycomb material evaluated was 

3.175 mm (0.125 in.) thick, composed of polycarbonate material, and featured a circular cell 

structure. The honeycomb materials maximized the amount of bonding area to the front panel, 

which typically inhibited front face cracking. Bonding areas could be reduced to allow for more 

cracking of the front face, however, the support of the honeycomb structure inhibits flexure, 

thereby working against crack propagation. 

Several other rib designs were conceived to enhance powder release and yet prevent the 

settling of powder that might reduce its effectiveness to impacts in certain areas. One design 

included sections of hollow acrylic tubing aligned horizontally and spaced at vertical distances of 

one inch or less. Both the tubes and the spaces between the tubes were filled with powder to 

ensure total coverage to threat impact. This rib design provided significant panel stiffness due to 

the amount of bonding surface area and seemed to provide leverage for sections of the front face 

to flex and break out. Another design concept was to use strips of solid plastic oriented 

horizontally in a fashion similar to the tubes. In these trials, the width of the solid strips was 

minimized since powder would not be present in these locations during a projectile impact. 

Tests were conducted with the number of these ribs minimized, the spacing maximized, and the 

overall panel thickness minimized. These panels were relatively stiff due to the strength of the 

panel face-to-rib bonds, but allowed for significant flexing of the front face due to the rib 

spacing. This rib arrangement required several tradeoffs. Ribs that formed channels too far 

apart allowed powder settling or bulging of the face sheets, but allowed for flexure of the front 

face during impact, which optimized cracking. Rib channels that were too close together 

prevented powder settling, but were more prone to function like honeycomb and provide too 

much support to the front face, reducing the likelihood of significant cracking. In these rib 

arrangements, powder along the length of the panel could be released from all open channels, 

which afforded greater performance than a honeycomb design. In a honeycomb design, only the 

cells penetrated or torn around the perimeter of the impact will release powder, unless significant 

cracking or area is removed from the front face. 

A corrugated aluminum of approximately 1.5875 mm (0.0625 in.) peak-to-peak height 

was also examined in some tests. The metal did not show a propensity to break up in these tests, 

so the front face would need to break up and separate for the panel to be effective. Some of the 

benefits of this design are similar to the channel design, however, the combination of metal and 

plastic in these trials may have some operational environment drawbacks, such as significantly 

different coefficients of thermal expansion. This design, the acrylic tube design, and variations 

of the horizontal plastic strip design allowed for filling of the powder panel after the panel was 
26

nearly assembled. Only the one edge had to be sealed after filling. This design variation could 

offer some improvement for assembly. 

Phase I testing was able to identify novel powder panel designs with enhanced 

performance over more standard design concepts. Tables 5-1 and 5-2 describe some of the 

panels tested. Table 5-1 lists some of the more novel and effective designs, while Table 5-2 lists 

some designs that feature more baseline design concepts and less effective performance. 

Appendix B lists all of the panels tested in Phase I. The tables indicate the mass of each powder 

panel, which were all about 30.16 cm x 30.16 cm (11.875 in. x 11.875 in.) in size. Total powderfilled weights for panels tested in the first year of testing ranged from 428.2 g (0.944 lb.) to 

1,403.0 g (3.093 lbs.). Most of the weight difference is due to varying thicknesses of the panels, 

with the weight of the powder contributing significantly because of increased panel internal 

volume. By contrast, commercial panels obtained during this NGP project weighed between 175 

g and 189 g for a similar size. Obviously, this was one design feature requiring optimization in 

Phase II testing. 

Table 5-1. More Effective Powder Panel Designs In Experimental Testing

Test 

No. 

Material Description Thickness 

(mm) 

Panel 

Weight 

(g) 

Powder 

Release 

(g) 

% Powder 

Released 

Front Face 

Area 

Removed 

(cm2) 

8 2.03 mm clear acrylic faces, 9.53 mm 

acrylic tube ribs 

13.5 1402 48 5.6 31.6

9 1.78 mm cracked ice acrylic front, 1.52 

mm ABS back, two ABS ribs (3.05 mm 

thick) 

6.9 769 23 5.0 17.7

12 2.03 mm (50.8 mm x 50.8 mm scored) 

clear acrylic, 2.03 mm clear acrylic back, 

3.18 mm polycarbonate honeycomb rib 

7.6 579 9 4.6 22.6

21 1.78 mm acrylic prismatic front, 1.52 

mm ABS back, two ABS ribs (3.05 mm 

thick) 

7.8 552 30 12.8 20.3

23 1.78 mm styrene prismatic front, 1.52 

mm ABS back, two ABS ribs (3.05 mm 

thick) 

6.5 517 28.4 12.8 25.6

27 2.49 mm polyester resin front, 1.52 mm 

ABS back, two ABS ribs (3.05 mm 

thick) 

7.1 620 8.2 4.0 25.4

28 2.49 mm polyester resin front, 1.52 mm 

ABS back, two ABS ribs (3.05 mm 

thick) 

7.4 876 83.3 18.7 80.6
27

Table 5-2. Less Effective Powder Panel Designs In Experimental Testing 

Test 

No. 

Material Description Thickness 

(mm) 

Panel 

Weight 

(g) 

Powder 

Release 

(g) 

% 

Powder 

Released 

Front Face 

Area 

Removed 

(cm2) 

1 0.41 mm Al front, 5.33 mm 

polyethylene corrugated rib, 0.25 mm 

Al foil back 

6.0 630 0.6 0.17 1.3

2 0.25 mm Al foil front, 5.2 mm 

polyethylene corrugated rib, 0.41 mm 

Al back 

5.9 594 0.04 0.01 1.3

13 1.52 mm ABS faces, 9.53 mm aramid 

rib 

13.5 1128 1.5 0.2 1.3

14 1.78 mm textured acrylic front, 2.03 

mm clear acrylic back, 6.35 mm Al 

honeycomb rib 

10.5 832 1 0.23 1.3

15 1.52 mm ABS faces, 6.35 mm Al 

honeycomb rib 

10.2 764 1 0.25 1.3

16 2.03 mm clear acrylic faces, 6.35 mm 

Al honeycomb rib 

10.8 942 3 0.65 1.6

18 2.03 mm (5.08 cm x 5.08 cm scored) 

clear acrylic front, 2.03 mm clear 

acrylic back, 3.18 mm Al honeycomb 

rib 

7.2 638 2 0.82 9.5

Some measures of effectiveness are also noted in Tables 5-1 and 5-2, including powder 

release or loss as a result of the ballistic test, percentage of the powder released, and the front 

face area removed. The estimate of the powder release is determined by comparing the panel 

weight before and after each test and weighing/estimating panel material lost. In cases where the 

panel was not effective at dispersing the powder, the hole on both faces of the panel may have 

been virtually the same size as the projectile (approximately 12.7 mm diameter). In other cases, 

a significant amount of the front face material may have been lost (Figure 5-1). Obviously, in 

these cases, a significant amount of powder was also released from the panel. The amount of 

powder released during testing varied from a fraction of a gram in some of the more standard 

designs to over 100 g. 
28

Figure 5-1. Test Example of Significant Panel Fracture and Material Loss 

A review of the Phase I test data indicated a wide disparity in the reaction of the panels. 

In some tests, the powder release was negligible, i.e., no powder was detected on the witness 

rods and no powder deposited in the cups. In these ineffective powder panel tests, more powder 

is actually observed exiting the back of the panel, along with the projectile, versus entering the 

dry bay. In other tests (Figure 5-2), the cloud of powder in the dry bay engulfed the entire dry 

bay and remained for a matter of minutes. Many tests resulted in some minute residue in the 

cups that was more likely spall from the powder panel front face and/or ribs, rather than the 

powder. In tests of effective powder panel concepts, powder was observed on all the witness 

rods and measurable powder weights were observed in all six cups. The amount of powder 

deposited in the collection cups has varied during testing from no trace to over seven grams by 

weight. Typically, 0.05 g or less was captured in any single cup, with the highest concentration 

of the powder being closest to the powder panel, as expected. Twenty different witness rods 

were placed throughout the dry bay and visible powder was noticed in more effective tests on all 

of the witness rods. To further verify the dispersion of the powder for effective designs, several 

panels were tested with dry bay clutter and powder was still observed on all witness rods, even 

those in isolated areas. 
29

Figure 5-2. Test Example of Effective Powder Release and Dispersion 

The most promising of the new powder panel designs examined in this project offer the 

potential to be competitive with halon 1301 in a wider variety of dry bay designs. In one of these 

cases (epoxy primer front face), nearly 50% of the front face area was removed, almost 60% of 

the powder was released, and the powder remained suspended throughout the dry bay for over 

four minutes. This occurred despite the fact that this was one of the thinnest panels tested. This 

compares with testing of other powder panel designs integrated into operational aircraft, where 

the powder disperses only along the shotline, dissipates in tenths of a second, and the amount of 

dispersed powder was limited to the region of projectile penetration (approximate powder release 

of a few percent) (Reference 28). 

Figures 5-3, 5-4, and 5-5 show major performance benefits achievable with some of the 

enhanced design concepts listed in Table 5-1 (by test number) over more standard powder panel 

designs (Table 5-2). Results indicated the powder panel front face area removed could be 

increased by 15 to 20 times over more standard designs (Figure 5-3). Testing also revealed the 

amount of powder released into a dry bay could be increased 5 to 10 times with an enhanced 

powder panel design (Figure 5-4). Testing also indicated that powder dispersion could be 

enhanced, even with dry bay clutter, ensuring the prevention of fire ignition over a wider area 

(Figure 5-5). In this figure, the number of witness rods with detectable powder residue is 

indicated for each test. Effective designs resulted in powder being suspended in the dry bay for 

much longer periods of time than standard powder panels (as much as four minutes in one test 

compared to one second or less). Finally, the design and fabrication effort revealed enhanced 

powder panels afforded greater design flexibility, which can be utilized to target weight, 

durability, and other application-specific design goals. These findings revealed that new powder 

panel concepts could significantly enhance the fire extinguishing effectiveness of this 

vulnerability reduction method, thereby demonstrating the feasibility of enhanced powder panels. 
30

Front Face Removal

0

10

20

30

40

50

60

70

80

90

7 Powder Panels from Both Categories

Front Face Area Removed (sq. cm.)

More Standard Design Elements

Promising Enhanced Designs

8

9

12 21

23

28

27

1 2 13 14 15 16

18

Figure 5-3. Effect on Powder Panel Fracture Area of Standard Design Features and 

Enhanced Designs, Showing 15x to 20x More Front Face Area Removed in the Latter 

Powder Release

0

5

10

15

20

7 Powder Panels from Both Categories

% of Powder Release

More Standard Design Elements

Promising Enhanced Designs

8

9 12

21

23

27

28

1 2 13 14 15 16 18

Figure 5-4. Effect on Powder Delivery of Standard Design Features and Enhanced 

Designs, Showing 5x to 10x Greater Powder Release in the Latter 
31

Witness Rods

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

1234567

7 Powder Panels from Both Categories

No. of Witness Rods with Visible Powder (out of 20)

More Standard Design Elements

Promising Enhanced Designs

8 9 12 21 23 27 28

1

2

13

14

15

16

18

Figure 5-5. Effect on Powder Dispersion of Standard Design Features and Enhanced 

Designs, Showing Greater Dispersion in the Latter 

Experimental observations indicate, as predicted, that the front face material properties 

are of utmost importance. More brittle materials outperformed ductile materials (that resist 

fracturing) by releasing more powder into the dry bay. The projectile seemed to melt its way 

through polycarbonate and polypropylene materials, and even some polystyrene materials, 

resulting in little or no powder released into the dry bay. Acrylic front face panels and faceted 

acrylic and styrene materials reacted in a much more brittle nature, resulting in lost material or 

cracking that more effectively released powder into the dry bay. One acrylic panel with a 

prismatic square pattern actually did not perform very well. It appears the pattern on the panel 

actually inhibited crack growth. Mixed results were found during testing of scored acrylic 

panels. Some cracking seemed to follow scoring lines in the vicinity of the impact that may have 

contributed to more material loss. However, comparisons between 5.08 cm (2 in.) and 10.16 cm 

(4 in.) scoring patterns showed that cracks emanating from the hole area, created directly by the 

projectile impact, were actually prevented from growing longer, i.e., scoring lines acted as crack 

stoppers. With appropriate scoring designs, though, it appears crack growth optimization 

techniques could be used to enhance performance. 

A strong synergism was found between the rib structure and the front face. Increasing 

the bond surface area between the front face and ribs inhibited powder dispersion for the designs 

tested. Results indicated that standard honeycomb ribs resisted greater front face cracking 

because of the increased number of bond sites. Experiments bonding honeycomb materials to 

the front face in a reduced number of selected areas, such as the panel perimeter, proved 

effective for polycarbonate honeycomb, but not necessarily for the aluminum honeycomb. It 
32

was reasonable to conclude from the testing, weaker and fewer bonding sites would allow both 

designs to function more effectively, as previous work has shown. Multiple explanations were 

plausible for the more effective polycarbonate tests. It is probable there was a contribution from 

the more brittle properties of the polycarbonate, which did fracture in some locations, and the 

design of the aluminum honeycomb likely distributed the impact energy over a greater surface 

area without allowing critical flexure of the front face. Design concepts using channels or 

horizontal ribs proved to be associated with the most effective powder panels, particularly when 

a more frangible front face was used. Channel designs allowed more powder to be released from 

the impact location than more segmented or cellular designs. Tradeoffs would be necessary for 

these designs between rib spacing and powder loading, as sufficient powder must be available at 

all potential impact sites, but more powder translates to greater weight. Testing indicated threepiece powder panel designs outperformed easy-to-assemble double-wall extrusion designs, as 

built-in rib channels inhibited cracking. 

Variation in the powder panel back face had much less effect on powder panel 

performance than the front face or rib design. A number of tests involved less brittle ABS 

material for the back face, since it is postulated that a smaller hole in the back face may actually 

mitigate the chance of a dry bay fire by reducing fuel leakage and confining it to an area along 

which most of the powder is released. This would provide a second means to increase powder 

panel effectiveness. The first being the use of a more brittle front face to maximize fire 

extinguishing powder release, while the flammable fluid leakage is minimized. Experimental 

testing did reveal that the front face of the powder panel can be designed to fracture and release 

large amounts of powder, while minimizing the damage to the panel back face. Phase I testing 

did not involved a fluid-filled tank, thereby eliminating hydrodynamic ram pressures on the fuel 

tank wall and reducing the chance of damage to the back face. In the tests involving ABS, the 

damage sustained by the back face was a hole just larger than the diameter of the 12.7 mm 

diameter ball projectile. 

5.2 Live Fire Proof-of-Concept Demonstration Test Results 

 Following the experimental testing of Phase I, the opportunity for demonstrating 

enhanced powder panels arose at the Navy’s Weapons Survivability Laboratory. Lessons 

learned from the NGP Phase I experimental testing were used to design and fabricate some new, 

slightly more optimized powder panels. These panels again incorporated thermoplastic 

materials. However, thinner panel thicknesses and reduced powder loading resulted in reduced 

weights, and new panel designs were utilized. Weights were decreased on average 100 to 200 g 

(0.22 to 0.44 lb.) from those designs evaluated in experimental testing for 30.16 cm x 30.16 cm 

(11.875 in. x 11.875 in.) panels. Panels at China Lake varied from 320 g (0.71 lb.) to 422 g (0.93 

lb.) in weight. Thicknesses ranged from 2.41 mm (0.095 in.) to 3.30 mm (0.13 in.). 

In both the JTCG/AS and FAA test programs, the enhanced powder panels showed a 

solid improvement over current powder panel designs. Fire ignition was prevented in all five 

valid tests involving enhanced powder panels (four JTCG/AS and one FAA test). Conversely, 

fires resulted in all four valid commercial powder panel tests (two JTCG/AS and two FAA tests). 

Figure 5-6 shows some images captured from high-speed video in JTCG/AS testing 
33

demonstrating the fire mitigation capability of enhanced powder panel designs. Powder 

discharge was estimated to be at least 90% of the pretest powder loading for the enhanced 

powder panels, compared to 5% to 10% for commercial powder panels. Greater powder 

dispersion throughout the dry bays was also evident for the enhanced powder panels. Figure 5-7 

compares the amount of fire extinguishing powder released from an enhanced powder panel with 

a commercially available powder panel in the JTCG/AS tests. 

Incendiary

Function

Fire

Ignition

Fire

Sustains

Incendiary

Function

Fire

Prevented

Dry Bay Engulfed

in Powder

Commercial

Powder Panels

Enhanced

Powder Panels

Figure 5-6. Enhanced Powder Panel Fire Mitigation Capability Demonstrated 
34

Commercial Powder Panel

~5-10% Powder Release

Enhanced Powder Panel

~90% Powder Release

Figure 5-7. Comparison Of Commercial And Enhanced Powder Panel Agent Release In 

JTCG/AS Dry Bay Fire Extinguishing Testing 

Figure 5-8 shows that impact of the enhanced powder panel by a rotor blade in the FAA 

test resulted in release of all the fire extinguishing agent, as it prevented fire ignition. Baseline 

testing showed that unprotected fuselage areas did indeed result in sustained fires. 

Figure 5-8. Entire Contents of Enhanced Powder Panel Released During FAA Test and 

Fire Prevented 
35

5.3 Parametric/Optimization Experimental Results 

 Following the successful conclusion of these live fire demonstration tests, Phase II 

parametric experiments began with the goal of optimizing successful enhanced powder panel 

designs identified in Phase I. Some lessons learned from the fire tests were also incorporated 

into the initial designs for Phase II. 

A total of 25 tests were conducted in Phase II optimization tests in Range A at the AVSF. 

Table 5-3 lists the panels tested and includes pretest panel weights and areal densities, along with 

the amount of powder release, percentage of powder released, and the estimated front face area 

removed. The panels are listed in descending order by the amount of powder released in each 

test. 

Table 5-3. Phase II Optimization Testing 

Test 

No. 

Material Description Total 

Thickness 

(mm) 

Pretest 

Weight 

(g) 

Areal 

Density 

(g/cm2) 

Powder 

Release 

(g) 

% 

Powder 

Released 

Front 

Face 

Area 

Removed 

(cm2) 

5 0.635 mm polystyrene front 

1.27 mm polycarbonate ribs 

0.508 mm polycarbonate back 

2.41 295.00 0.324 5.15 3.2 11.1 

22 0.762 mm acrylic front 

0.762 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.29 215.34 0.237 4.03 8.4 6.03 

24 0.508 mm composite front 

0.762 mm polycarbonate ribs 

0.381 mm polycarbonate back 

1.65 141.03 0.155 3.02 6.3 1.46 

8 0.762 mm acrylic front 

1.27 mm polycarbonate ribs 

0.762 mm polycarbonate back 

3.05 347.96 0.382 2.99 1.8 11.87 

18 0.635 mm polystyrene front 

0.762 mm polycarbonate ribs 

0.508 mm polycarbonate back 

1.91 331.76 0.365 2.51 1.2 1.61 

14 0.635 mm polystyrene front 

1.27 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.67 368.46 0.405 2.17 1.9 9.75 

2 0.635 mm polystyrene front 

0.762 mm polycarbonate ribs 

0.508 mm polycarbonate back 

2.41 251.60 0.277 2.15 1.8 4.84 

10 0.762 mm acrylic front 

1.27 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.79 453.13 0.498 2.06 0.7 1.26 

4 0.635 mm polystyrene front 

1.27 mm polycarbonate ribs 

0.508 mm polycarbonate back 

2.41 330.00 0.363 1.66 0.8 24.58 

23 0.508 mm composite front 

0.762 mm polycarbonate ribs 

0.381 mm polycarbonate back 

1.65 140.02 0.154 1.61 2.8 1.67 
36

Table 5-3. Phase II Optimization Testing (Continued) 

Test 

No. 

Material Description Total 

Thickness 

(mm) 

Pretest 

Weight 

(g) 

Areal 

Density 

(g/cm2) 

Powder 

Release 

(g) 

% 

Powder 

Released 

Front 

Face 

Area 

Removed 

(cm2) 

17 0.635 mm polystyrene front 

0.762 mm polycarbonate ribs 

0.508 mm polycarbonate back 

1.91 329.95 0.363 1.52 0.8 1.98 

6 0.635 mm polystyrene front 

0.762 mm ABS ribs 

0.762 mm ABS back 

2.16 201.20 0.221 1.36 1.5 9.81 

11 0.635 mm polystyrene front 

1.27 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.67 403.94 0.444 1.04 0.7 7.74 

13 0.635 mm polystyrene front 

1.27 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.67 410.54 0.451 0.82 0.5 3.02 

16 0.635 mm polystyrene front 

0.762 mm polycarbonate ribs 

0.508 mm polycarbonate back 

1.91 306.32 0.337 0.78 0.4 1.61 

7 0.635 mm polystyrene front 

0.762 mm ABS ribs 

0.762 mm ABS back 

2.16 193.48 0.213 0.75 0.9 5.81 

21 0.635 mm polystyrene front 

0.762 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.16 191.47 0.210 0.63 1.2 1.26 

9 0.076 mm glass epoxy front 

0.1” Nomex honeycomb ribs 

0.076 mm glass epoxy back 

2.69 174.95 0.192 0.26 0.2 1.11 

15 0.076 mm glass epoxy front 

0.1” Nomex honeycomb ribs 

0.076 mm glass epoxy back 

2.69 174.99 0.192 0.24 0.2 0.49 

19 1.016 mm polycarbonate front 

0.762 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.54 269.68 0.296 0.14 0.3 0.71 

20* 1.016 mm polycarbonate front 

0.762 mm polycarbonate ribs 

0.762 mm polycarbonate back 

2.54 260.74 0.287 N/A N/A 0.71 

25* 0.508 mm composite front 

0.762 mm polycarbonate ribs 

0.381 mm polycarbonate back 

1.65 123.96 0.136 N/A N/A 19.17 

*Tests conducted with water in fuel tank; not able to accurately determine powder release. 

A summary of the designs is also provided in Table 5-3, listing the front and back face 

materials and the material thickness. Effective front face materials tested in Phase I were 

evaluated, including a textured polystyrene. Some other materials were also examined, including 

other thermoplastics and some composite materials not evaluated in Phase I. Materials used for 

the back face concentrated on polycarbonate, which proved to be effective in Phase I, although 

some tests were conducted with ABS, a more ductile material. Table 5-3 also shows the rib 

materials tested and the thicknesses of the internal section of the panel. Different rib designs and 
37

manufacturing processes were examined in the optimization testing. Rib materials most often 

mirrored the back face material. 

Optimization testing indicated significant decreases in weight were possible from Phase I 

test panels, while maintaining improved powder release. Enhanced powder panels weights were 

reduced as much as 57% in weight from the lightest panel tested in the first phase, with an 

increase in powder release. Figure 5-9 compares the lightest Phase II panel with the lightest 

Phase I panel and a commercial powder panel. Two of the lightest pretest filled panel weights 

were 123.96 g (0.27 lb.) and 140.02 g (0.31 lb.). By comparison, commercial powder panels 

tested in Phase II weighed approximately 175 g (0.39 lb.). Therefore, the enhanced powder 

panels were reduced as much as 29% below the commercial panel weight. 

Filled Powder Panel Weight

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

Phase I Lightest

Enhanced Powder

Panel

Phase II Lightest

Enhanced Powder

Panel

Commercial Powder

Panel

Weight (g)

Figure 5-9. Phase II Enhanced Powder Panel Weight Reduction 

Enhanced powder panel thicknesses ranged between 1.65 mm (0.065 in.) and 3.05 mm 

(0.120 in.) in optimization evaluations. This was a reduction of more than 60% from the thinnest 

panel tested in Phase I. Commercial panels evaluated in Phase II were 2.69 mm (0.106 in.) in 

thickness. The enhanced powder panels were, therefore, reduced about 39% in thickness below 

the commercial powder panel. Figure 5-10 compares the thinnest panels tested in Phase I and 

Phase II with the commercial powder panels. Reductions in thickness reduce the powder loading 

or the amount of powder in the panel, which is the significant weight consideration. However, 

the thickness of the panel along the shotline also reduces the potential powder release, which 

obviously affects powder panel effectiveness. Therefore, there is a balance necessary between 

panel thickness, which affects panel weight, and the effectiveness of the panel, as measured by 

powder release or loss. Front and back face materials and the rib structure design were other 

variables examined to increase performance without increasing weight. 
38

Powder Panel Thickness

0.00

1.00

2.00

3.00

4.00

5.00

Phase I Thinnest

Enhanced Powder

Panel

Phase II Thinnest

Enhanced Powder

Panel

Commercial Powder

Panel

Thickness (mm)

Figure 5-10. Phase II Enhanced Powder Panel Thickness Reduction 

Powder release is an important factor in the testing because the greater the amount of 

powder dispersed in the dry bay, particularly along the shotline, the lower the chance of an 

ignited fire. The amount of powder released in Phase II testing ranged from as low as 0.14 g to 

as much as 5.15 g. This powder release or loss is not as much as the most effective panels in 

Phase I testing, but the panel thickness and available powder has been significantly reduced to 

meet likely design goals. Powder release for the commercial powder panel tests was 0.24 and 

0.26 g. Figure 5-11 compares the best performing Phase II enhanced powder panel (no water in 

the tank) with the best performing commercial powder panel. This data shows the amount of 

powder released from the enhanced powder panels was as much as 21 times greater than the 

commercial powder panels. 

Estimated Powder Release

0

1

2

3

4

5

6

Phase II Panel - Greatest Powder

Release

Commercial Powder Panel

Powder Release (g)

Figure 5-11. Comparing Enhanced and Commercial Panel Powder Release 
39

The percentage of powder released (powder released or lost divided by pretest total 

powder loading multiplied by 100%) has also been used as a measure of powder release 

effectiveness. The enhanced powder panel design attempts to maximize the release of the 

available powder in the panel. Optimized panels tested ranged from 0.3% to 8.4% of the total 

powder released. The commercial panels released approximately 0.2% of the total powder 

contained. Figure 5-12 compares the best performing Phase II enhanced powder panel (no water 

in the tank) with the best performing commercial powder panel. This data shows the enhanced 

powder panels could increase the percentage of total powder released by as much as 42 times. A 

ranking of the panels using percentage of powder released does not track directly with a ranking 

of the panels by total powder released, since there was some considerable variance in overall 

pretest panel weight. 

Estimated % Powder Released

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

Phase II Panel - Greatest %

Released

Commercial Powder Panel

% Powder Released

Figure 5-12. Comparing Enhanced and Commercial Panel Percent Powder Released 

Tests 9 and 15 in Table 5-3 were conducted on the commercially available powder 

panels. As mentioned previously, these panels are composed of a honeycomb core and two thin 

composite face sheets. The commercial powder panels were among the lighter panels tested 

(empty weight and with powder), but also released nearly the least amount of powder and the 

smallest percentage of powder. Except for one test examining a ductile front face, the powder 

release and percentage of powder released for the commercial panels is less than half the next 

enhanced powder panel. As discovered in previous testing with Nomex honeycomb cores, 

powder is released from those cells directly penetrated by the projectile and those torn on the 

perimeter of the penetration either by the penetrating projectile or hydrodynamic ram forces 

acting on the fuel tank panel. However, the damage area is relatively well contained and powder 

is not able to escape from the rest of the panel. Enhanced powder panels offer the potential for a 

much greater percentage of the panel’s contents to be released. It was anticipated at this point in 
40

the program that the effects of hydrodynamic ram on the powder panel will only increase the 

amount of improvement an enhanced powder panel can offer. Further testing would verify this 

assertion. 

The outlier enhanced powder panel (Test 19) utilized polycarbonate throughout the 

design, including the front face. In this test, the entrance hole in the front face and exit hole in 

the rear face essentially self-sealed together and prevented virtually any powder from escaping, 

except through the penetration area alone. This design was also examined in Test 20 with water 

in the fuel tank and yielded the same damage. The front face area removed for these tests was 

approximately 0.71 cm2

 (0.11 in.2), the worst performance by an enhanced powder panel. By 

contrast, Test 4 resulted in almost 25 cm2

 (3.875 in.2) of the front face removed and Test 25, with 

water, resulted in over 19 cm2

 (2.945 in.2) being removed. Figure 5-13 compares the enhanced 

powder panel experiencing the greatest front face area removal (no water in the tank) with the 

better performing commercial powder panel (1.11 cm2

 [0.172 in.2]). An improvement of over 22 

times is shown with this enhanced powder panel. 

Estimated Front Face Area Removal

0

5

10

15

20

25

30

Phase II Panel - Greatest Area

Removed

Commercial Pow der Panel

Front Face Area Removed (sq cm)

Figure 5-13. Comparing Enhanced and Commercial Panel Front Face Area Removal 

For Tests 20 and 25, conducted with water in the fuel tank, a post-test weight of the panel 

to determine powder release or loss was not practical. The powder in both panels absorbed water 

as a result of the test. These two tests, however, demonstrated that hydrodynamic ram would 

significantly enhance front face fracture for a more brittle front face, leading to greater powder 

release, but would not likely assist fracture for a ductile front face. Front face area removal was 

increased for the same panel design by as much as 12 times (comparing Test 24 to Test 25) due 

to the additional forces and fuel tank panel deformation associated with hydrodynamic ram. This 

result demonstrated that in cases were the powder panel will be attached to a flammable fluid 

container, and hydrodynamic ram is expected when the container is punctured, the powder panel 

can be designed to take advantage of the expected hydrodynamic ram event. 
41

 Summarizing Phase II optimization testing, the data showed that an enhanced powder 

panel (Test 24) can be 19% lighter and 39% thinner than a commercial powder panel, yet release 

over 10 times more powder mass, 30 times greater the percentage of powder originally contained 

in the panel, and sustain at least 32% greater front face area removal. The data also showed that 

the effects of hydrodynamic ram would further increase the performance of an enhanced powder 

panel. 

5.4 Live Fire Demonstration Test Results of Optimized Enhanced Powder Panels 

 Some of the more practical, yet effective enhanced powder panels were evaluated in live 

fire demonstration tests conducted at the end of Phase II. This testing involved many of the same 

test elements involved in proof-of-concept testing after Phase I. However, in these tests, the 

thinner and lower weight Phase II optimized panels were evaluated. A total of nine tests were 

conducted, as described in Table 5-4. The test was set up to ensure a threat function for each 

powder panel test. A successful powder panel test was considered to be one where no fire 

ignition occurred. Estimates of the front face area removed and the percentage of powder 

released were made. Due to the presence of JP-8 fuel, it was not possible to weigh the precise 

amount of powder released or lost, so an estimate of the percentage of the original powder 

released was made. This was a rough estimate based upon a post-test examination of the panel 

and area calculations. It was impossible to determine the influence of leaking fuel on remaining 

powder in the panel immediately after the test, but the estimates do correlate well with powder 

dispersion evidence and fire ignition results. 

 Two different enhanced powder panel designs were evaluated in the demonstration tests, 

with the primary differences involving material composition. Enhanced Design 1, in Table 5-4, 

is a lighter weight design with potentially better thermal resistance capability. Enhanced Design 

2 is more robust in terms of durability, but is heavier. Test EPP-08 varied in design somewhat 

from the Enhanced Design 1, utilizing a self-sealing back face material, but was essentially the 

same in other respects. 
42

Table 5-4. Phase II Enhanced Powder Panel Live Fire Demonstration Tests 

Test 

No. 

Powder 

Panel 

Panel 

Weight 

(g) 

Panel 

Thickness 

(mm) 

Powder Threat 

Function?

Fire 

Ignition? 

Front 

Face 

Area 

Removed 

(cm2) 

Estimated 

% 

Powder 

Released 

EPP01 No Panel -

Baseline 

N/A N/A N/A Yes No N/A N/A 

EPP02 No Panel -

Baseline 

N/A N/A N/A Yes Yes N/A N/A 

EPP03 Commercial 189.05 2.69 Al2O3 Yes Yes* 50 8 

EPP04 Enhanced 

Design 1 

145.44 1.905 Al2O3 Yes No 156.5 70 

EPP05 Enhanced 

Design 1 

140.78 1.905 Al2O3 Yes Yes* 145.5 83 

EPP06 Enhanced 

Design 2 

186.5 1.905 Al2O3 Yes No 309.2 88 

EPP07 Enhanced 

Design 2 

227.02 1.905 KHCO3 Yes Yes, but 

powder 

extinguished 

fire 

329.4 83 

EPP08 Enhanced 

Design 1 

157.06 2.134 Al2O3 Yes No 54.1 61 

EPP09 Enhanced 

Design 2 

226.34 2.159 KHCO3 Yes No 252.2 62 

*Panel dislodged from fuel tank wall during test 

 Two baseline tests were conducted at the beginning of the test program. The purpose of 

these tests was to ensure threat functioning and the ignition of a fire in an unprotected or 

inadequately protected dry bay. For these conditions, a successful powder panel would prevent 

fire ignition, despite the functioning threat, and an unsuccessful powder panel would not prevent 

fire ignition. In the first baseline test, the fuel tank panel was a 2.032 mm (0.08 in.) thick 7075-

T6 plate. This was the same material and thickness used as the simulated fuel tank panel in all 

Range A experimental tests. In EPP-01 a fire was not ignited, as a large deluge of fuel was seen 

engulfing the dry bay almost immediately, creating an extremely fluid rich environment. The 

threat did function, but the fuel tank panel resisted the significant hydrodynamic ram pressures 

and peeled away from the fasteners attaching it to the fuel tank. The fuel tank panel deformed 

significantly before its edges at the fastener locations tore through, but the impact hole was not 

significantly larger than the threat size. The toughness of this material was also evident in the 

Range A tests, where hydrodynamic ram was most often not a variable and worst-case conditions 

were desired. In these demonstration tests, it was desired to allow hydrodynamic ram damage to 

occur. Without hydrodynamic ram forces and minimized fuel spurting, it is possible an 

inaccurate judgment could be made regarding powder panel effectiveness. In this first baseline 

test, the panel resisted hydrodynamic ram forces such that the weakest failure point was the fuel 

tank panel attachment mechanism. 
43

 Since a fire was not ignited in this first test (and the potential for fire was essential for the 

powder panel evaluations), modifications were made to the test article and setup to better ensure 

fire ignition. For the second baseline test, the fuel tank material was changed to 1.803 mm 

(0.071 in.) thick 2024-T3 and a structural frame was used to hold the fuel tank panel to the fuel 

tank without interfering with the powder panel positioned between its boundaries. In addition, 

the planned projectile velocity was lowered to 762 m/s (2,500 ft./s) to mirror proof-of-concept 

testing after Phase I and to reduce energy somewhat. The fuel level was lowered from 

completely full (about 64.35 l [17 gal.]) to about 3⁄4 full (49.21 l [13 gal.]) to permit pressure 

relief in an ullage area and reduce the amount of fuel that might immediately spill out into the 

ignition zone and create another over-rich condition. These modifications proved worthwhile, as 

EPP-02 did result in a fire. The fire was visible for about four seconds, but appeared to be selfextinguishing near that time. This would provide an adequate burn time for an evaluation of the 

powder panels, but an alteration to the test article was envisioned to be necessary. 

 The third test (EPP-03) involved a commercial powder panel, as Table 5-4 indicates. The 

threat functioned as planned, however a fire was ignited. The fire only lasted a short duration, as 

the fire appeared to be lean and seeking oxygen. A long jet of flame actually shot out of the 

entrance hole at the front of the dry bay. The fire lasted over a second, but thick black smoke 

from the combustion filled the dry bay and lasted for many minutes afterward. The temperature 

in the dry bay climbed about 120°F. The conclusion was that the panel was not successful in 

inhibiting fire ignition or preventing a sustained fire, rather a self-extinguishing fire occurred due 

to a lack of oxygen. Closer inspection of the dry bay and the high-speed video revealed the 

commercial powder panel did not remain adhered to the fuel tank panel with the two-part epoxy 

used. The panel was dislodged after the threat flash and started coming loose as the fire was 

ignited below and almost behind the panel as it flew off. The powder release was not sufficient 

to allow powder to remain suspended in the dry bay, however, its effectiveness could remain in 

question since it did not adhere properly. Black markings evident of not only a flash, but of an 

ignited fire, were present in the dry bay. No powder residue was found in the dry bay following 

the test, although the panel did break up better than in non-fluid tests in Range A (Figure 5-14). 

The damage area was approximately 10.2 cm high x 6.4 cm wide (4 in high x 2.5 in. wide). It is 

estimated from an inspection of the panel that the front face area removed was approximately 50 

cm

2

 (7.75 in2) and about 8% of the powder was released. 
44

Figure 5-14. Post-Test Damage Image of EPP-03 Commercial Powder Panel 

 The fourth test (EPP-04) involved an enhanced powder panel. For this test, modifications 

to the test article were considered to allow more venting or fresh oxygen to be available to the 

combustion process. However, since more enhanced powder panel tests were to be conducted, it 

was desired to conduct at least one with the exact same conditions as the commercial powder 

panel for a direct comparison. In this test, the threat functioned as expected, with the high-speed 

video indicating a flash duration of approximately 0.008 seconds or more, which was 

comparable to the previous two tests. However in this test, as soon as the flash dissipated, the 

dry bay was engulfed in fire extinguishing powder, and no fire ignition occurred. The 

temperature in the dry bay around the flash climbed only about 20°F. A review of the video 

confirmed that no combustion occurred after the threat function. Powder was visible on the 

walls of the dry bay, with powder on the Lexan window all the way to the end of the four ft. long 

dry bay. A significant amount of powder also covered the striker panel on the surface facing the 

powder panel. Powder was also visible in the dry bay for a number of minutes after the test. The 

panel was adhered with a two-part, fast curing epoxy, which was the same adhesive used in the 

commercial panel test. However, in this case the panel held fairly well, although some loss of 

adhesion occurred. Figure 5-15 shows a post-test image of the powder panel, demonstrating the 

front face fracture. The damage area was approximately 14.4 cm high x 17.8 cm wide (5.675 in 

high x 7 in. wide). It is estimated from an inspection of the panel that the front face area 

removed was approximately 156.5 cm2

 (24.25 in.2) and about 70% of the powder was released. 
45

Figure 5-15. Post-Test Damage Image of EPP-04 Enhanced Powder Panel 

 In preparation for EPP-05, the dry bay test article was modified to allow for more fresh 

air to vent into the fire zone. A 7.62 cm (3 in.) diameter hole was drilled into the aluminum side 

wall of the dry bay. It was centered along the length of the dry bay, 0.61 m (2 ft.) from the fuel 

tank wall and down about 13.3 cm (5.25 in.) from the top of the dry bay. In this test, a doublesided adhesive tape was used to adhere the powder panel, versus a two-part epoxy. The threat 

functioned in the test, as planned, and the high-speed video showed a fire ignited about 0.02 

seconds after the flash dissipated. The fire lasted several seconds and the temperature climbed 

about 349°F in the dry bay near the fuel tank. In the real-time and high-speed video, the powder 

panel was visible being dislodged from the fuel tank and slamming into the side Lexan panel. 

The fire started behind the powder panel in the corner opposite the direction the powder panel 

flew off. Powder was visible in the video emanating from the panel into the Lexan and down 

onto the floor. As the panel lay against the Lexan, continued powder leakage was visible onto 

the floor and it suspended in the vicinity of the dry bay. It is unclear if the continued release of 

powder was responsible for the fire extinguishing later or if the fire self-extinguished. Inspection 

of the test article did indicate some black residue around the new dry bay opening, so the extra 

vent did provide an oxygen source to the fire. In this test, the powder panel design was exactly 

the same as in EPP-04. In addition, the powder panel broke up at least as effectively as in EPP04, so it was surmised that if the panel had not dislodged from the fuel tank wall, it would likely 

have prevented a fire. However, further tests were required to determine if the additional oxygen 

available would hinder the effectiveness of the enhanced powder panels. The post-test damaged 

powder panel is shown in Figure 5-16. The front face damage area was approximately 17.8 cm 
46

high x 15.2 cm wide (7 in high x 6 in. wide). The front face area removed was approximately 

145.5 cm2

 (22.55 in.2). About 83% of the powder was released, but as described, much of this 

may have exited the panel as it flew into the Lexan side panel and then rested against it. 

Figure 5-16. Post-Test Damage Image of EPP-05 Enhanced Powder Panel 

 Test EPP-06 involved a different enhanced powder panel design, primarily involving a 

change to the front face material. It also marked the first test using MIL-S-8802 aircraft sealant, 

rather than a faster curing epoxy sealant, as the adhesive to attach the powder panel to the fuel 

tank wall. All tests conducted after EPP-05 used this adhesive. This powder panel and all the 

panels utilizing this sealant remained well adhered to the fuel tank during testing. In this test, the 

flash was visible in the high-speed video, and then powder was seen once again engulfing the dry 

bay with no fire ignition occurring. The temperature in the dry bay climbed no more than about 

26°F near the flash. Powder seemed to distribute well and quickly. Powder was still lingering in 

the dry bay nearly fifteen minutes after the test, when the side panel was removed (Figure 5-17). 

Upon inspection of the fuel tank, powder was visible along the length of the Lexan window and 

across the surface of the striker plate facing the powder panel (Figure 5-18). Some large pieces 

of the powder panel front surface were actually stuck to the striker plate along with the powder. 

Powder was also detected on the aluminum side panel nearly the length of the dry bay. Powder 

was also visible on the structural framework of the dry bay. In all of the powder panel tests, 

sufficient fuel leaked into the dry bay to make visible powder on the surface of the fuel very 

difficult to distinguish. 
47

Figure 5-17. Powder Suspension in the Dry Bay Well After the Test 

Figure 5-18. Powder Dispersion on Striker Plate and Side Lexan Panel 
48

 As shown in Figure 5-19, the powder panel was fractured in EPP-06 similar to the 

previous enhanced powder panel tests. The front face damage area extended nearly to edges of 

the panel, measuring approximately 30.2 cm high by 27.3 cm wide (11.875 in high x 10.75 in. 

wide). The front face area removed was approximately 309.2 cm2

 (47.92 in.2) and about 88% of 

the powder was released. 

Figure 5-19. Post-Test Damage Image of EPP-06 Enhanced Powder Panel 

 In Test EPP-07, KHCO3 was used as the fire extinguishing powder, rather than Al2O3, to 

examine any difference in powder release or powder dispersion. The panel design was the same 

as in EPP-06. In this test, however, powder loading was increased and the panel weighed 

approximately 22% more. In this test, the threat functioned as planned for a duration of less than 

0.016 second. After the flash dissipated, the powder is seen in the video beginning to engulf the 

dry bay. However, a fire is ignited in the lower corner of the dry bay near the fuel tank panel and 

Lexan panel. It lasted only about 0.28 second as the powder is seen reaching this area about the 

time it is extinguished. The temperature in the dry bay climbed no more than 30°F near the fuel 

tank. A small leak was evident from the fuel tank in pretest preparations and it occurred in this 

corner. It is plausible that some fuel remained in this corner of the dry bay after the leak was 

fixed. This likely allowed for an ignition of fuel already present in the dry bay, before fuel from 

the threat penetration hole fully began to spray into the dry bay. Based upon the evidence 

provided, this powder panel was considered successful, despite the brief ignition of a fire, 

because the powder was considered responsible for extinguishing the fire. Upon inspection of 
49

the test article, powder was evident on the Lexan panel and aluminum side panel similar to the 

previous test. Powder was also evident on the dry bay structural framework, top panel, and 

striker plate. As expected, the KHCO3 was somewhat easier to distinguish than the Al2O3. The 

powder panel front face fracture was similar to EPP-06, as shown in Figure 5-20. The front face 

damage area extended nearly to edges of the panel again, measuring approximately 30.2 cm high 

x 27.3 cm wide (11.875 in high x 10.75 in. wide). The front face area removed was 

approximately 329.4 cm2

 (51.05 in.2) and about 83% of the powder was released. 

Figure 5-20. Post-Test Damage Image of EPP-07 Enhanced Powder Panel 

 Test EPP-08 utilized Al2O3 and used the same front face material evaluated in Tests EPP04 and EPP-05. This panel had a slightly wider total thickness (2.134 mm [0.084 in.]) than these 

previously tested enhanced powder panels, but still weighed less than the commercial powder 

panel tested. This test also involved the use of a self-sealing material for the back face. In this 

test, the threat functioned as planned and no fire was ignited. The cloud of powder quickly 

moved throughout the dry bay. The temperature in the dry bay climbed no more than 23°F. 

Powder was evident along the length of the Lexan panel and the other aluminum side panel. It 

was also found on the striker plate facing the powder panel and the dry bay top wall and back 

wall. The front face area removal was somewhat reduced from previous panels using the same 

front face, but cracking was extensive, allowing large flaps of material to easily release powder 

(Figure 5-21). The damage area extended about 28.9 cm high x 23.8 cm wide (11.375 in. high x 

9.375 in. wide). The front face area removed was approximately 54.1 cm2

 (8.39 in.2) and about 
50

61% of the powder was released. The hole in the back face of the powder panel was 

approximately 1.27 cm x 1.27 cm (0.5 in. x 0.5 in.), resulting in an area removal about 66% less 

than any of the other enhanced powder panel tests. It is, therefore, likely that less fuel was 

immediately available for fire ignition than in tests without a self-sealing back face. It is 

believed the thickness of the back face could be increased for such a design to improve selfsealing capability, while still maintaining an overall weight and thickness comparable to 

commercial powder panels. A test to verify this assertion was not possible during this test 

program. 

Figure 5-21. Post-Test Damage Image of EPP-08 Enhanced Powder Panel 

 The final Phase II live fire demonstration test (EPP-09) again involved KHCO3. The 

same design used in Tests EPP-06 and EPP-07 was used, except the panel internal width was 

wider, and, therefore the overall panel was wider (2.159 mm). Despite the increased thickness, 

powder loading was such that it was very close in weight to EPP-07, which also examined 

KHCO3. A large flash was evident in this test upon review of the high-speed video. However, 

no fire was ignited. The temperature in the dry bay near the flash climbed on average around 

37°F. A large cloud of powder enveloped the dry bay and powder was visible striking the Lexan 

wall. Both side walls had visible powder deposits, as well as the top panel beyond the striker 

plate, and the striker plate itself. When the side wall was removed more than five minutes after 

the test, a large cloud of powder was still evident in the dry bay (Figure 5-22). The damage to 

the enhanced powder panel front face was significant, as shown in Figure 5-23. The damage 
51

area extended about 30.2 cm high x 25.7 cm wide (11.875 in. high x 10.125 in. wide). The front 

face area removed was approximately 252.2 cm2

 (39.09 in.2) and about 62% of the powder was 

released. 

Figure 5-22. Powder Evident in Dry Bay More Than Five Minutes After EPP-09 Test (Side 

Wall Removed) 
52

Figure 5-23. Post-Test Damage Image of EPP-09 Enhanced Powder Panel 

 The results of the Phase II live fire demonstration tests were very promising. Out of six 

enhanced powder panel tests, only one test was considered unsuccessful, and it was likely due to 

the lack of adherence of the panel to the fuel tank. This problem was associated with the 

selection of adhesive for attaching the panel to the fuel tank, not the panel design itself. The 

same panel design was able to prevent fire ignition in two other tests. The commercial powder 

panel was unsuccessful in preventing fire ignition, but it too failed to adhere to the fuel tank 

panel. The amount of powder released, however, did not make the chance for success seem 

likely, even if it did adhere. Demonstration testing after Phase I at China Lake, with many of the 

same test conditions including the ballistic threat, showed these panels were not effective under 

these conditions. In these NGP demonstration tests, the enhanced powder panels released at least 

87% more powder than the commercial powder panel. Except for one enhanced powder panel, 

which still released significantly more powder, the size of the front face area removed was at 

least 34% better for the enhanced powder panels compared to the commercial powder panel. 

Thinner enhanced powder panels appeared to release more of the total panel’s powder 

content. However, they also likely contained less powder, so the total powder release may have 

been fairly close to the thicker panels. The powder panel utilizing a self-sealing back face (EPP08) did appear to sustain less front face break-up than other enhanced powder panels. This could 

have been a result of this design variation. However, the reduction in the size of the back face 

hole, also likely contributed to the panel effectiveness by reducing immediate fuel leakage. 
53

Both tests with KHCO3 resulted in successes, although Test EPP-07 did show evidence of 

a very brief fire ignition. It appeared the powder release did, however, result in the fire being 

extinguished. KHCO3 was expected to be at least as effective as Al2O3, however, the grain size 

of the KHCO3 was on average around 30 microns compared to the 5 micron Al2O3. As previous 

testing has shown, a smaller grain size has proven to be more effective in fire extinguishing. It is 

inconclusive, however, in these few tests, whether or not grain size was even a factor. 

It was conclusive that sufficient powder was released from each of the enhanced powder 

panels to significantly reduce the likelihood of a dry bay fire, regardless of the powder type. It is 

estimated that at least 40 g of powder was released in most of the enhanced powder panel tests, 

with as much as 60 or 70 g from the heavier panels. It is estimated the commercial powder panel 

likely released less than 10 g of powder. 
54

6. Important Findings and Conclusions 

This NGP project accomplished its original objectives to identify fire extinguishing 

powder panel concepts for enhancement (relative to current capability and halon 1301) and 

demonstrate proof-of-concept designs. It demonstrated the feasibility of enhanced powder 

panels and revealed enhanced powder panel designs could afford a number of benefits over 

current commercial powder panel designs. It also expanded upon the original objective and was 

able to optimize more promising enhanced powder panel designs to make them even more 

competitive with alternative fire extinguishing systems, including halon 1301. Finally, these 

optimized designs were then evaluated in live fire tests, demonstrating their ability to mitigate 

fire ignition in realistic dry bay areas. Although additional work is necessary to address 

manufacturing issues and ensure enhanced powder panels meet the requirements of individual 

aircraft programs, they are in a position to be considered as a potential alternative in future fire 

protection evaluations. 

Phase I NGP investigations examined current powder panel applications, baselined 

current powder panel design features, screened potential design and material improvements, and 

demonstrated the feasibility of more promising enhanced powder panel concepts. Phase II NGP 

investigations examined halon applications for comparison with enhanced powder panels, 

identified likely production requirements and issues for enhanced powder panels, parametrically 

examined design features to result in optimized enhanced powder panels, and demonstrated the 

optimized designs through live fire testing in a realistic dry bay. Findings from this research 

revealed that realistic powder panel concepts can significantly enhance the fire extinguishing 

effectiveness of this vulnerability reduction method. Enhanced powder panel designs can afford 

the following benefits over current commercial powder panel designs: 

• greater powder release into dry bay, 

• better dispersion of powder to prevent ignition off-shotline, 

• longer powder suspension to prevent fire ignition for longer period of time, 

• greater front face area removal to allow more powder to escape, 

• design flexibility of enhanced powder panels can be utilized to target weight, durability, 

and application-specific design goals, 

• and significantly improved fire extinguishing effectiveness over commercial powder 

panels can be achieved at an equal or lighter weight and thickness. 

Optimization goals were achieved for enhanced powder panels in this project. These 

goals were to lower enhanced powder panel weight and thickness to the levels of current 

commercial powder panels or below and demonstrate greater performance in live fire testing. 

Enhanced powder panels evaluated in final demonstrations ranged in weight from 140.78 g (0.31 

lb.) to 227.02 g (0.50 lb.), with four of the six panels being lighter than the commercial powder 

panel evaluated (189.05 g or 0.42 lb.). Thicknesses ranged from 1.905 mm (0.075 in.) to 2.159 

mm (0.085 in.), while the commercial powder panel thickness was 2.69 mm (0.106 in.). 

Live fire testing conducted in a dry bay of realistic size for an aircraft (0.45 m3

 [16 ft.3]), 

with an actual ballistic threat (12.7mm API), and at least 49.21 l (13 gal.) of JP-8, resulted in the 
55

prevention of fire ignition in four out of six tests. In a fifth test, a fire starting from an existing 

pool of fuel was quickly extinguished (after only 0.28 second) by an enhanced powder panel. 

The cause of a lone unsuccessful test resulting in a fire was attributed to an inadequate 

attachment adhesive on the back of the enhanced powder panel. The test of a commercial 

powder panel resulted in a fire, however the attachment adhesive again failed to hold. Although 

the commercial panel test was not conclusive, a further examination of the test results indicated a 

significant increase in vital performance characteristics for the enhanced powder panels. Despite 

being as much as 26% lighter and 29% thinner, the enhanced powder panel tests resulted in at 

least 34% greater front face area removal and at least four times greater powder release. Powder 

was evident on surfaces throughout the dry bay following enhanced powder panel tests and was 

visibly suspended in the dry bay up to five minutes after some of the enhanced powder panel 

tests. No evidence was present of dispersed and/or suspended powder in the commercial powder 

panel test. 

A number of lessons were learned about effective powder panel design. Some, 

previously discovered, were reaffirmed. Among the key lessons learned were: 

• brittle or frangible front face materials outperform ductile or tough materials, 

• front face crack growth optimization can be designed into the powder panel through the 

use of particular front face materials, thicknesses, rib designs, attachment methods to the 

ribs, and even surface scoring, 

• a strong synergism exists between the rib structure and the front face design, 

• and the back face can be designed to aid in powder dispersion and/or reduce fluid 

leakage. 

Another key finding in this program is that there are design features associated with 

enhanced powder panels that can make them very resistant to accidental leakage. With the use 

of plastics and certain composites, there are adhesives to attach the various elements of the panel 

that form extremely tight bonds. The selection of a front face material and thickness can take 

into account the likely harsh environment to which the powder panel will be exposed. 

Accidental leakage has been a significant concern for aircraft designers considering powder 

panels and is the primary reason that Al2O3 has been the only chemical fire extinguishing powder 

finding production usage. With this resistance to accidental leakage in certain designs, perhaps 

other lighter weight and improved performance fire extinguishing agents can be considered. Not 

only are other powders lighter in weight, but improved effectiveness of these powders may lead 

to reduced requirements for powder loading. 

To fully take advantage of the potential benefits from enhanced powder panels, further 

examination of the more promising designs should be performed for potential qualification test 

requirements. These may include, but are not limited to operating temperature, chemical 

exposure, vibration, impact resistance, and moisture absorption. These issues were considered in 

the selection of materials for Phase II optimization testing, but qualification testing for these 

parameters was not conducted. 

Despite significant increases in powder release for enhanced powder panels, a balance 

must be achieved between weight/thickness and effectiveness. For protection against larger 
56

threats, it may be warranted to consider higher powder loading, which is the significant weight 

driver. For strict weight restrictions, testing may be required for the given powder panel to 

determine the type and size of the threat for which protection is afforded. 

The principles that govern the final design features uncovered in this project were 

focused on ballistic testing and aircraft (fixed, rotary, tilt-rotor, and unmanned). However, they 

do not apply solely to simple projectile impact or these types of vehicles. Enhanced powder 

panels should be effective, even if subjected to other forces or if employed in any number of 

other applications. Further studies continue to determine the depth and breadth of these 

applications and the various factors influencing enhanced powder panel performance in these 

areas. 
57

7. Significant Hardware Developments 

 As the previous section detailed, enhanced powder panels have been developed with 

increased effectiveness over current powder panel designs at equivalent or better weight and size. 

These enhanced powder panel designs can now be examined for various applications, 

particularly in military aircraft, as a trade-off with other fire extinguishing systems. Additional 

work will be required with the examination of production design requirements, which may cause 

some adjustments in the selection of materials or sizing, but the design principles should be in 

place. Some manufacturing concepts were developed and others conceived as a result of this 

work, which will need to be optimized for production application. 
58

8. Implications for Further Research 

 The developments initiated by this project have sparked other research and development 

proposals and an internal research and development investment by Skyward itself. A Joint 

Aircraft Survivability Program Office (JASPO) proposal has been evaluated favorably and may 

lead to further investigations into design requirements and qualification testing that could result 

in a production-ready form of the enhanced powder panels. Other efforts are underway to 

achieve this goal regardless of the success of this proposal. Interest has been shown by a number 

of aircraft programs seeking alternative fire protection methods, including lightweight, passive 

means. Efforts will continue to address their concerns and potential commercialization of 

enhanced powder panels. 
59

9. References 

1. Cyphers, D.C., Frederick, S.A., and Haas, J.P., "Enhanced Powder Panels", The 

Proceedings of the 12th Halon Options Technical Working Conference, Albuquerque, NM, 

Paper 10, pp. 1-12, Albuquerque, NM, April 30 - May 2, 2002. 

2. Cyphers, D.C., Frederick, S.A., and Haas, J.P., “Demonstrating Enhanced Powder Panels”, 

The Proceedings of the 13th Halon Options Technical Working Conference, Albuquerque, 

NM, May 13-15, 2003. 

3. Seymour, Timothy J. and Ellenwood, Peter S., 1Lt, USAF, “Powder Pack Fire Protection 

for Aircraft Dry Bays”, AFWAL-TR-84-3119, June 1985. 

4. Pascal, Andrew, “B-1B LFT&E Dry Bay Fire Test Series Data Analysis (U)”, Enthalpy 

Corporation, June 1997. 

5. Finnerty, Anthony E., Vande Kieft, Lawrence J., and Drysdale, Andrew, “Physical 

Characteristics of Fire-Extinguishing Powders”, ARL-TR-1450, Army Research 

Laboratory, August 1997. 

6. Ewing, C.T., Highes, J.T., and Carhart, H.W., Fire and Materials, Vol.8, p.148, 1984. 

7. Dolan, J.E., Sixth Symposium on Combustion, NY: Reinhold, p. 787, 1956. 

8. Altman, R.L., Teng, A.C., Mayer, L.A. and Myronuk, D.J., “Development and Testing of 

Dry Chemicals in Advanced Extinguishing Systems for Jet Engine Nacelle Fires”, Report 

JTCG/AS-82-T-002, Joint Technical Coordinating Group for Aircraft Survivability, 1983. 

9. Finnerty, Anthony E., and Vande Kieft, Lawrence J., “Powders as Halon Replacements”, 

Proceedings of the 1997 Halon Options Technical Working Conference, Albuquerque, NM, 

May 6-8, 1997. 

10. Fischer, G., and Leonard, J.T., “Effectiveness of Fire Extinguishing Powders Based on 

Small Scale Suppression Tests”, NRL/MR/6180-95-7778, Naval Research Laboratory, 

October 19, 1995. 

11. Jaggers, Jerry F., “Development of Powder-Filled Structural Panels for AH-1S Fuel Fire 

Protection”, USAAVRADCOM-TR-81-D-32, Bell Helicopter Textron, October 1981. 

12. Peregino II, Philip J., Finnerty, Anthony E., Adkins, Thomas, McGill, Robert, Cline, 

Timothy, Gault, William, and Saunders, Dawnn, “Fire Protection for External Fuel Cells”, 

ARL-MR-413, U.S. Army Research Laboratory, October 1998. 

13. Finnerty, Anthony E. and Polyanski, Stanley, “Powder Packs – A Passive Approach to 

Extinguishing Fire in Combat Vehicles”, Technical Report BRL-TR-3191, U.S. Army 

Ballistic Research Laboratory, January 1991. 

14. Finnerty, Anthony E. and Dehn, James T., “Alternative Approaches to Fuel-Fire Protection 

for Combat Vehicles”, ARL-TR-377, U.S. Army Research Laboratory, April 1994. 

15. Finnerty, Anthony E., McGill, Robert L., Slack, Wayne A., and Saunders, Dawnn M., 

“Fuel Cells in a Composite Armored Vehicle”, ARL-TR-1911, March 1999. 

16. Pedriani, Charles M., “Ballistic Testing of Advanced Fire Suppression Systems Designed 

to Protect Helicopter Fuel Tanks from 23mm High Explosive Incendiary-Tracers (HEI-T)”, 

USAAVRADCOM TM 80-D-3, February 1980. 

17. Jaggers, Jerry, Fox, Roy, Johnson, Jack, and Liardon, Darrell, “Development of 

Survivability and Vulnerability Improvement Modifications (SAVIM) for the AH-1S 

Helicopter, Appendix C – Vulnerability Analysis and Crew Protection”, 

USAAVRADCOM-TR-81-D-29, Bell Helicopter Textron, May 1982, CONFIDENTIAL. 
60

18. Kiser, B. L., “Helicopter SAVIM Advanced Development Program”, USAAVSCOM TR84-D-14, Bell Helicopter Textron Inc., October 1984. 

19. Keane, Christopher A., “Vulnerability Reduction Technology for Rotary Wing Aircraft,” 

Master’s Thesis, Naval Postgraduate School, June 1998. 

20. Robaidek, M.F., “Aircraft Dry Bay Fire Protection”, AFWAL-TR-87-3032, Boeing 

Military Airplane Company, July 1987. 

21. Pedriani, Charles M., “Testing of Powder Packs and Powder-Filled Structures for Aircraft 

Fire Protection,” USAAVRADCOM-TR-82-D-12, JTCG/AS-81-T-002, July 1982. 

22. Mercer, M., “A Ballistic Evaluation of Lightweight Void Fillers”, JTCG/AS-87-T-004, 

Naval Weapons Center, September 1987. 

23. Finnerty, Anthony E., “Preliminary Evaluation of Powder Packs”, Memorandum Report 

BRL-MR-3641, December 1987. 

24. Kolleck, M.L., “Halon Fire Protection Systems for Aviation - Existing System 

Configuration and Operational Environment Specifications”, Preliminary Report, prepared 

for Halon Replacement Program for Aviation Team, December 1992. 

25. Manchor, J.A., “V-1-04 Reactive Powder Panels” briefing, JTCG-AS Project V-1-04, 

NAVAIR, September 2002. 

26. Lundin, S.J., “Uncontained Engine Debris Tests - Fuselage Fire - Advanced Powder Panel” 

data CD-ROM, NAVAIR and FAA, October 28, 2002.

27. Haas, John P., Murphy, John J., Jr., “C-130 Vulnerability Reduction Program/C-130J Live 

Fire Test Program Test Report, Phase IA - Wing Leading Edge Dry Bay Testing (U)”, 

AAC TR 00-14, February 2001 (SECRET). 

28. Manchor, Joseph A., “Reactive Powder Panel Ballistic Demonstration” briefing, JTCG-AS 

Project V-1-04, NAVAIR (NAWCWD Code 418300D), January 2001. 
61

10. Bibliography 

Presented the following papers: 

• Cyphers, D.C., Frederick, S.A., and Haas, J.P., "Enhanced Powder Panels", The Proceedings 

of the 12th Halon Options Technical Working Conference, Albuquerque, NM, Paper 10, pp. 

1-12, Albuquerque, NM, April 30 - May 2, 2002. 

• Cyphers, D.C., Frederick, S.A., and Haas, J.P., “Demonstrating Enhanced Powder Panels”, 

The Proceedings of the 13th Halon Options Technical Working Conference, Albuquerque, 

NM, May 13-15, 2003. 

• Haas, J.P., Cyphers, D.C., and Frederick, S.A., “Enhanced Powder Panel Concepts”, Twenty 

Seventh Annual American Institute of Aeronautics and Astronautics Dayton-Cincinnati 

Aerospace Science Symposium, Dayton, OH, March 5, 2002. 

Presented the following poster papers: 

• Cyphers, D.C., Frederick, S.A., and Haas, J.P., “Enhanced Powder Panels”, Aircraft 

Survivability 2002 - Combat Survivability: UAVs and Manned Aircraft, Monterey, CA, 

November 18-21, 2001. 

• Cyphers, D.C., Frederick, S.A., and Haas, J.P., “From Concept to Demonstration - The 

Evolving Enhanced Powder Panel Story”, Aircraft Survivability 2003: Reclaiming the Low 

Altitude Battlespace, Monterey, CA, November 3-6, 2002. 

The following paper was accepted and is pending publication: 

• Cyphers, D.C., “Enhanced Powder Panels - Applying New Ideas to an Old Fire 

Extinguishing Method”, Military Fire Protection Systems Edition, FS-World.com Magazine. 
62

11. Appendices 
APPENDIX A 

PHASE II OPTIMIZED POWDER PANEL 

LIVE FIRE DEMONSTRATION TEST PLAN

ENHANCED POWDER PANEL DEMONSTRATION 

TEST PLAN 

PROJECT 5E/1/12 

NEXT GENERATION FIRE SUPPRESSION TECHNOLOGY PROGRAM (NGP) 

DANIEL C. CYPHERS 

SCOTT A. FREDERICK 

JOHN P. HAAS 

SKYWARD, Ltd. 

5100 SPRINGFIELD STREET, SUITE 418 

DAYTON, OHIO 45431-1264 

JUNE 2003 

This research is part of the Department of Defense’s Next-Generation Fire Suppression Technology Program, funded by the DoD Strategic 

Environmental Research and Development Program (SERDP)
ii

TABLE OF CONTENTS 

Section Page

1.0 Introduction.............................................................................................................................. 1 

2.0 Testing Approach..................................................................................................................... 1 

2.1 Objectives........................................................................................................................ 1 

2.2 Data Requirements ..........................................................................................................2 

2.2.1 Instrumentation........................................................................................................ 2 

2.3 Testing............................................................................................................................. 3 

2.3.1 Test Facilities .......................................................................................................... 3 

2.3.2 Test Article and Setup............................................................................................. 4 

2.3.3 Threat Description................................................................................................... 8 

2.3.4 Test Matrix ..............................................................................................................8 

2.3.5 Test Procedures ..................................................................................................... 10 

3.0 Safety Issues .......................................................................................................................... 12 

4.0 Documentation....................................................................................................................... 12 

Figure Page

Figure 1. AVSF Range 2................................................................................................................ 3 

Figure 2. Side View of Dry Bay, Prior to Modification for Test-Ready Configuration ................ 4 

Figure 3. End View of Dry Bay, Prior to Modification for Test-Ready Configuration................. 5 

Figure 4. Overall Test Article Concept (Top and Lexan Side Removed for Clarity).................... 6 

Figure 5. Test Article Setup in Range 2......................................................................................... 7 

Figure 6. 12.7mm API Type B-32 Projectile Description ............................................................. 8 

Table Page

Table 1. Test Matrix....................................................................................................................... 9 

Table 2. Pretest and Test Procedures ........................................................................................... 11 

Table 3. Post-Test Procedures...................................................................................................... 12 
1

1.0 Introduction 

 Powder panels are not a new concept for extinguishing ballistic threat-induced fires in 

aircraft. They have in fact been around for many years. However, a number of factors have 

renewed interest in powder panel technology. First, the production of halon has been banned due 

to its ozone depleting potential. New techniques will be needed to fill the role of halon in 

aircraft fire extinguishing. Also, new materials, powders, and construction techniques have been 

developed which may allow for improved powder panel performance (both system weight and 

fire extinguishing capability). Therefore, this test program is being performed to assist in 

identifying fire extinguishing powder panel concepts for enhanced performance. 

2.0 Testing Approach 

 The purpose of this testing is to demonstrate enhanced powder panels optimized in Phase 

II of NGP Project 5E/1/12 can effectively prevent fires in a dry bay/fuel tank simulator. These 

demonstration tests will show that optimization of materials and designs did not degrade the 

effectiveness of enhanced powder panel prototype designs in suppressing ballistic threat-induced 

dry bay fires. Phase II of this two-phase NGP project concentrated on optimization of the more 

promising designs identified in Phase I. Design variations were examined to optimize size, 

weight, durability, and practicality, while maintaining increased performance over standard 

powder panels. While threat encounter parameters are likely to be important to the overall 

output response, the limited scope of this program will necessitate fixing those parameters 

related to the threat. These tests will include parameters conducive to starting a fire and a test 

article more representative of a full-scale dry bay compared to the test device used in previous 

experiments. 

 Optimized enhanced powder panel designs will be tested in a realistic dry bay/fuel tank 

test article by penetrating the panels with a realistic ballistic threat. Testing will be conducted in 

Range 2 of the Aerospace Vehicle Survivability Facility (AVSF). Range 2 is capable of housing 

tests involving JP-8 fuel and 12.7mm armor piercing incendiary (API) projectiles, including the 

ability to extinguish a fire generated during the course of such testing. The velocity and 

obliquity chosen for testing will be fixed and replicate as closely as possible a realistic combat 

encounter. The testing will be designed to characterize the ballistic threat interaction with the 

leaking fuel from a penetrated fuel tank and the potential for fire suppression from fire 

extinguishing powder released by the penetrated powder panel. 

2.1 Objectives 

The overall objective of this project is to identify powder panel concepts for 

enhancement, relative to current capability and halon 1301, and demonstrate proofs of concept. 

In order to satisfy the project objective, current powder panel technology will be characterized 

and recent improvements in powder panel materials and construction will be assessed. The 

ultimate goal of this work is the development of enhanced powder panel concepts that are 

competitive with halon 1301 in critical parameters such as weight, volume occupied, fire 

extinguishing capability, etc. and, thus are candidates for use in its place. 
2

The Phase II test objective is to optimize effective designs identified in Phase I. The 

objective of this test series is to demonstrate through proof-of-concept testing the most promising 

enhanced powder panel concept. 

 This test series objective will be met by: 

• Performing baseline ballistic tests without protection, 

• Performing a ballistic test with a standard commercial powder panel 

• Performing ballistic tests on optimized enhanced powder panels 

• Measuring the temperature achieved within the test article dry bay 

• Capturing video of ballistic test event 

• Determining whether or not the fire was suppressed 

• Observing the powder distribution following each test event 

2.2 Data Requirements 

The primary data collected will involve optical footage of the events transpiring within 

the dry. Primarily, the data must show whether or not conditions were appropriate for a fire to 

start without protection, and whether or not enhanced powder panels were able to prevent dry 

bay fires. Factors that affect how the powder is dispersed, including threat and panel responses, 

will also be collected. Impact dynamics data will be analyzed, such as panel fracture 

characteristics and damage mechanisms. 

2.2.1 Instrumentation 

Threat Velocity Measurement Equipment - The projectile velocity at impact will be 

calculated for each test. The projectile impact velocity is calculated by measuring the elapsed 

time required to travel from the gun barrel muzzle to the target (striker plate in this case). A gun 

break wire is installed in a small hole drilled in the side of the barrel near the exit end. The wire 

is severed as the projectile exits the muzzle. A break-paper grid is located at the intended impact 

point on the striker plate. The break-paper grid is broken when the projectile impacts the target. 

With the break wire and break paper time increments determined and the standoff distance 

known, the impact velocity can be calculated. If the paper grid and strain gage should fail before 

impact, the projectile velocity can still be estimated using the gun break signal and the pressure 

transducer signal recorded on the Nicolet data acquisition system. 

Thermocouples - Temperature magnitude-time histories will be collected to obtain a 

temperature profile for the dry bay test article. Thermocouples will be located within the dry bay 

(2). All thermocouples will operate in the 0° to 2,400°F range with a 1 kHz sampling rate. One 

thermocouple will be located on the back side of the striker plate below the target location and 

the other near the fuel tank wall above the powder panel. Exact locations are not critical. 

Thermocouples will be inspected and tested prior to each test to assure proper functioning. 

Optical Records - A high-speed video camera (approximately 500 frps) will be mounted 

beside the test article and will record the view looking through a lexan panel on the side of the 

test device. Skyward will provide a digital video camera (approximately 30 frps) that will also 
3

record the event through the lexan panel. Both cameras will be aimed toward the powder panel, 

but cover as much of the dry bay as possible. A standard video camera (30 frps) will be 

positioned more distant and will focus on the overall test article to capture the entire event. 

2.3 Testing 

Up to ten ballistic tests will be conducted, including unprotected and powder panelprotected configurations of the dry bay/fuel tank simulator. The test article and test setup will be 

very similar to enhanced powder panel tests conducted in Aug 02 at the Weapons Survivability 

Laboratory at China Lake, California. These tests involved proof-of-concept testing of enhanced 

powder panels. 

2.3.1 Test Facilities 

The testing will be conducted in Range 2 (Figure 1) of the 46th Test Wing Aerospace 

Survivability and Safety Flight (AVSF). This range is located at Wright-Patterson Air Force 

Base, OH, and is operated by the Aerospace Survivability and Safety Flight (46 OG/OGM/OLAC). Range 2 is typically utilized for such programs as fuel cell inerting, hydrodynamic ram 

evaluations, ballistic flammability, material and component ballistic tolerance, and threat 

characterization. 

RANGE 2

Figure 1. AVSF Range 2 
4

2.3.2 Test Article and Setup 

The test article consists of two parts. The first consists of an aluminum/steel/Lexan box 

representing an aircraft dry bay (Figures 2 and 3). Its dimensions are 2 feet wide x 4 feet long x 

2 feet high for a dry bay volume of 16 ft3

. Steel L-angle forms the structure of this box. The top, 

bottom, and one side (length direction) of the box will consist of aluminum panels in the test 

configuration. The other side panel will be composed of Lexan to allow viewing of the event by 

the video cameras during testing. The one end of the test article positioned toward the West 

(projectile entrance direction) in the test setup will consist of an aluminum panel with an 

approximately 3 inch diameter or 3 inch x 3 inch square hole. This hole will allow the projectile 

to enter the test article. The other end of the dry bay simulator will consist of an aluminum 

frame panel to allow a second box to attach. This frame will be used to attach the second box, 

but will sized so it does not overlap the 1 foot x 1 foot powder panel positioned in its center, as 

the conceptual view of the overall test article shows in Figure 4. A striker plate will be attached 

to the internal frame of the dry bay approximately one foot in front of the fuel tank front face. 

The striker plate, composed of 0.250 inch thick 7475 aluminum, will be no more than 6 inches in 

width to allow fire extinguishing powder from the powder panel to disperse around it. If the 

striker plate can be secured from lower attachment points, it will not extend to the top of the dry 

bay. 

Figure 2. Side View of Dry Bay, Prior to Modification for Test-Ready Configuration 
5

Figure 3. End View of Dry Bay, Prior to Modification for Test-Ready Configuration 
6

Existing Dry Bay Box

Aluminum Panel

Shotline

Frame for Fuel Tank Attachment

Striker plate

Fuel Tank

Powder Panel

Figure 4. Overall Test Article Concept (Top and Lexan Side Removed for Clarity) 

 The fuel tank will measure at least 1 foot 2 inches wide by 1 foot deep (along shotline) by 

2 feet high. The width of the tank must allow for the powder panel to be adhesively bonded to 

the center of the front face and still allow it to be attached to the dry bay simulator. The volume 

below the powder panel location may be sectioned off to lower the amount of required fuel. The 

fuel level does not have to be completely full, but must be at least 6 inches above the impact 

location. The volume of the fuel tank will, therefore, be approximately 1.75 cubic feet, holding 

just less than 13 gallons of JP-8 fuel. The front face of the fuel tank will allow for removable 

panels. These removable panels will be 0.08 inches thick and composed of 7075-T6 aluminum, 

unless sufficient hydrodynamic ram damage is not observed. A decision may be made to use 

2024-T3 aluminum of 0.071 inch thickness in subsequent tests, if not. This panel will be secured 

to the fuel tank with L-angle stiffeners and bolts. The remaining panels of the fuel tank will 

likely be composed of steel to sustain repeated hydrodynamic ram pressures. The back panel 

will be reinforced with a “soft” aluminum panel in front of it to capture the armor piercing 

rounds. No air gap will be allowed to exist between the dry bay and fuel tank once attached. A 

drain will be placed in the fuel tank and dry bay, but fuel will not be drained from the dry bay 

until powder dispersion is documented by digital photographs and video. It is vital that the 

powder dispersion be documented before the dry bay is drained and rinsed out. 
7

The powder panels will be approximately 1 foot by 1 foot by 0.1 inch thick in size. They 

will be centered along the shotline and mounted to the front of the fuel tank front face panel 

using epoxy bonding or double-sided tape. The powder panel will fit inside of the frame of the 

back panel of the dry bay simulator to avoid any interference with the performance of the panels. 

The test article will be placed near the East wall of AVSF Range 2, with the fuel tank on 

the East side. The gun will be positioned to the West of the test article. The gun will be fired 

from the West toward the East wall of the range. This configuration is planned as a safety 

measure to ensure projectiles do not leave the range enclosure. Figure 5 shows the relative 

position of the test article and gun setup. 

Figure 5. Test Article Setup in Range 2 
8

2.3.3 Threat Description 

A single threat type will be used for each of the enhanced powder panel tests. The 

12.7mm API Type B-32 projectile will be fired through the center of the test article at a velocity 

of approximately 2,750 fps for the first baseline test and 2,500 fps for subsequent tests. Up to 

ten total ballistic tests will be conducted to gather data on the performance of the powder panels. 

A physical description of the projectile is provided in Figure 6. The projectiles will be fired from 

Mann barrels at close range to minimize targeting error, and the projectile powder weight will be 

modified, if necessary, to achieve the desired impact velocity. 

Figure 6. 12.7mm API Type B-32 Projectile Description 

2.3.4 Test Matrix 

The planned test matrix is listed in Table 1. No more than ten tests are planned for this 

program. The first test will be a baseline test without powder panel protection. The purpose of 

this test will be to demonstrate that the conditions specified in this program will indeed result in 

a dry bay fire, if no fire protection is included. If the results of this first test are inconclusive 

regarding the probability of a dry bay fire, a second baseline test may be conducted. The first 

primary test will involve a 12 inch by 12 inch commercial powder panel. This test will be 

conducted to determine if a current powder panel could prevent a fire for the given conditions. 

The subsequent primary tests will be conducted with enhanced powder panels. These tests will 
9

attempt to determine if the optimization techniques used to modify promising designs 

demonstrated in Phase I of this NGP project affected performance at all. 

Table 1. Test Matrix. 

Test No. Powder 

Panel 

Fuel / 

Quantity 

Striker Plate / 

Location 

Fuel 

Tank 

Panel 

Obliquity 

Angle (°) 

Threat 

(Type) 

Impact 

Velocity 

(fps) 

EPP-01 None JP-8 / Full 0.25 inch 

7475 / 

1 foot before 

powder panel 

0.08 inch 

7075-T6 

0° 12.7mm 

API 

2,750 

EPP-02 None JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-03 Commercial JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-04 Enhanced 1 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-05 Enhanced 2 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-06 Enhanced 3 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-07 Enhanced 4 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-08 

(If $ 

permits) 

Enhanced 5 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-09 

(If $ 

permits) 

Enhanced 6 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 

EPP-10 

(If $ 

permits) 

Enhanced 7 JP-8 / 

18 inches 

(3/4) 

0.25 inch 

7475 / 

1 foot before 

powder panel 

0.071 

inch 

2024-T3 

0° 12.7mm 

API 

2,500 
10

2.3.5 Test Procedures 

The procedures to be followed for each individual test are presented in Tables 2 and 3. 

These procedures must be followed to ensure the test objective is met for each test. The test 

setup must be reviewed prior to each test to ensure test preparations are in accordance with the 

test plan. This includes making sure the test objective will be satisfied and the correct data will 

be collected to support the post-test analysis. The key test procedures for this program involve 

the setup of the test article to ensure the appropriate powder panel is installed in the proper 

location, the fuel tank is filled, and the appropriate impact location on the striker plate is 

targeted. 
11

Table 2. Pretest and Test Procedures 

PRETEST

Pretest briefing. 

Weigh powder panel. 

Install fuel tank and striker plate panels. 

Install powder panel, if any. 

Attach fuel tank to dry bay. 

Fill fuel tank with JP-8 fuel. 

Locate impact point on striker plate. 

Dry fire and aim weapon. 

Console key to Range Safety Officer (RSO). 

Raise the flag. 

Ready cameras. 

Instrumentation check. 

Clear and activate range. 

Check specimen CO2 valve and put in off position. 

Facility CO2 check. 

Take zeros and calibrations. 

TEST

Load and arm weapon.

Turn master range power on. 

RSO gives key to console operator. 

All systems ready (Veridian test engineer, Skyward, safety). 

Arm the Nicolet system. 

Start 20 second countdown. 

T-15 seconds, turn on videotape recorders. 

T-8 seconds, arm weapon. 

T-2 seconds, start instrumentation data acquisition. 

T-0.5 second, start high-speed video camera. 

T-0 seconds, gun fired under computer control. 

T+5 seconds, if fire exists, activate HFC-125 @ test engineer's discretion. 

If fire escapes test article, activate CO2 @ test engineer’s discretion. 

End instrumentation data acquisition. 

End test.
12

Table 3. Post-Test Procedures 

POST-TEST

Backup instrumentation data. 

Turn off videotape recorders. 

Turn master range power off. 

Download weapon. 

RSO safety checks Range 2. 

RSO deactivates range. 

Turn off beacon and lower the flag. 

Visually document damage and powder dispersion. 

Drain fuel to proper location (Manifold or scrap). 

Remove remaining powder panel and weigh. 

Rinse dry bay test article and prepare for subsequent test. 

Review instrumentation data and video. 

Reduce raw data.

3.0 Safety Issues 

All testing will be accomplished in AVSF Range 2. All safety precautions for AVSF 

Range 2 will be followed throughout the course of testing. Hazardous material handling, 

including the handling and firing of foreign fuzed shells, will follow applicable Safety Permits. 

Protection of personnel and government property during testing will be the responsibility of the 

Range Safety Officer (RSO). If the RSO determines safety procedures/rules are not being 

followed, testing will be suspended or canceled. 

The principal safety issue with this testing will be the safe containment of the ballistic 

threat. The principal method of stopping the threat will be through a catch plate located on the 

back wall of the fuel tank test article. The East wall of Range 2 will be behind the test article if 

the projectile escapes. An external catch plate will be positioned on this wall as well. 

The powders to be used for testing are all non-toxic to humans. However, because the 

dry powder is a finely divided solid material, it can become suspended in the air causing a mild 

discomfort similar to that experienced in any dust-laden atmosphere. To minimize the exposure 

to the dust, all participants should be advised to use dust masks during test clean-up. 

4.0 Documentation 

All data will be recorded and analyzed following each test. A draft test report will be 

prepared and submitted to the Technical Program Manager (TPM) of the National Institute for 

Standards and Technology for the Next-Generation Fire Suppression Technology Program 

(NGP) in FY03. The final test report will incorporate government comments and be submitted 

back to the NGP TPM. 
13

The subject reports shall contain test conditions, a description of any deviations approved 

subsequent to the preparation of the Enhanced Powder Panel Test Plan, test results, and 

conclusions. The emphasis of the test report will be to document in as much detail as possible 

the results of optimized enhanced powder panel demonstration tests and their effectiveness. 

APPENDIX B 

PHASE I POWDER PANEL CONFIGURATIONS TESTED

1

Test 

No. 

Material Description Total 

Thickness 

(mm) 

Pretest 

Weight 

(g) 

Powder 

Release 

(g) 

% 

Powder 

Released 

Front Face 

Area 

Removed 

(cm2) 

Rear Face 

Area 

Removed 

(cm2) 

1 0.406mm Al front, 5.33mm 

corrugated polyallomer, 

0.254mm Al back

5.99 630.04 0.59 0.17 1.26 1.26

2 0.254mm Al front, 5.23mm 

corrugated polyallomer, 

0.406mm Al back

5.89 594.21 0.04 0.01 1.26 1.26

3 Double wall polypropylene 4.50 427.20 0.83 0.27 1.26 1.26

4 Double wall polycarbonate 6.58 561.65 3 0.67 3.23 2.84

5 Double wall polycarbonate, 

scored

6.58 704.56 3 0.51 2.84 3.87

6 1.524mm ABS faces, 

9.525mm acrylic eggcrate rib

12.40 962.90 minimal* minimal* 1.26 1.26

7 1.778mm (peak) acrylic 

prismatic faces, 9.525mm 

acrylic eggcrate rib

12.90 1038.20 7 1.14 1.29 6.45

8 2.032mm clear acrylic faces, 

9.525mm acrylic tube ribs

13.49 1401.60 48 5.56 31.61 31.61

9 1.778mm textured acrylic 

front, 1.524mm ABS back, 

two ABS ribs (3.048mm thick) 

at 10.16cm and 20.32cm

6.91 769.40 23 5.02 17.74 1.29

10 1.778mm acrylic prismatic 

front, 1.524mm ABS back, 

two ABS ribs (3.048mm thick) 

at 10.16cm and 20.32cm

7.19 829.50 10 3.39 1.94 1.29

11 10.16cm x 10.16cm scored 

clear 1.524mm acrylic front, 

2.032mm clear acrylic back, 

3.175mm polycarbonate 

honeycomb rib

6.91 574.00 7 3.55 16.13 2.84

12 5.08cm x 5.08cm scored clear 

acrylic, 2.032mm clear acrylic 

back, 3.175mm polycarbonate 

honeycomb rib

7.59 579.00 9 4.64 22.58 3.23

13 1.524mm ABS faces, 

9.525mm Nomex rib (PN2-

1/8-6.0)

13.49 1128.00 1.5 0.2 1.26 2.84

14 1.778mm textured acrylic 

front, 2.032mm clear acrylic 

back, 6.35mm Al honeycomb 

rib (PAMG-XR1-8.1-1/8-002-

5052)

10.49 831.80 1 0.23 1.29 3.23

15 1.524mm ABS faces, 6.35mm 

Al honeycomb rib (PAMGXR1-8.1-1/8-00205052)

10.21 764.00 1 0.25 1.26 2.84

16 2.032mm clear acrylic faces, 

6.35mm Al honeycomb rib 

(PAMG-XR1-8.1-1/8-002-

5052)

10.80 942.00 3 0.65 1.61 5.03
2

Test 

No.

Material Description Total 

Thickness 

(mm)

Pretest 

Weight 

(g)

Powder 

Release 

(g)

% 

Powder 

Released

Front Face 

Area 

Removed 

(cm2)

Rear Face 

Area 

Removed 

(cm2)

17 1.524mm ABS faces, 

9.525mm hollow acrylic tube 

ribs

13.31 1268.30 1 0.13 1.29 1.29

18 5.08cm x 5.08cm scored 2.032 

mm clear acrylic front, 

2.032mm clear acrylic back, 

3.175mm Al honeycomb rib

7.19 638.10 2 0.82 9.55 2.84

19 0.076mm epoxy primer sheet 

front, 1.524mm ABS back, 

two ABS ribs (3.048mm thick) 

at 10.16cm and 20.32cm

5.59 441.40 135 57.23 426.45 1.29

20 1.778mm acrylic prismatic 

front, 1.524mm ABS back, 

1.5875mm Al corrugation

5.59 433.70 4 2.52 7.26 2.84

21 1.778mm acrylic prismatic 

front, 1.524mm ABS back, 

two ABS ribs (3.048mm thick) 

at 10.16cm and 20.32cm

7.80 552.00 30 12.82 20.26 2.84

22 1.778mm styrene prismatic 

front, 1.524mm ABS back, 

1.5875mm Al corrugation

5.41 328.30 1 1.75 5.03 1.29

23 1.778mm styrene prismatic 

front, 1.524mm ABS back, 

two ABS ribs (3.048mm thick) 

at 10.16cm and 20.32cm

6.50 516.80 28.4 12.78 25.61 2.00

24 1.499mm fiberglass polyester 

resin front, 1.524mm ABS 

back, two ABS ribs (3.048mm 

thick) at 10.16cm and 

20.32cm

6.30 721.70 Unable Unable 153.23 2.00

25 1.524mm polyester resin front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm

6.50 746.10 1.6 0.58 1.29 2.00

26 Double wall polypropylene, 

scored, panel - on dry bay wall

4.29 402.26 2.22 0.56 2.00 3.03

27 2.489mm polyester resin front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm

7.06 620.00 8.19 4 25.42 2.00

28 2.489mm polyester resin front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm

7.39 875.80 83.3 18.7 80.65 2.00

29 2.54mm epoxy resin front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm

7.11 790.60 10 3.33 24.52 2.00
3

Test 

No. 

Material Description Total 

Thickness 

(mm) 

Pretest 

Weight 

(g) 

Powder 

Release 

(g) 

% 

Powder 

Released 

Front Face 

Area 

Removed 

(cm2) 

Rear Face 

Area 

Removed 

(cm2) 

30 1.27mm clear acrylic front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm

6.70 597.40 18 6.77 31.42 2.00

31 1.27mm clear acrylic front, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm, dry bay 

clutter

6.20 596.20 35 13.61 28.19 2.00

32 2.489mm polyester resin front 

with embedded border rib, 

1.524mm ABS back, two ABS 

ribs (3.048mm thick) at 

10.16cm and 20.32cm, dry bay 

clutter

7.25 660.48 8 3.35 28.00 2.00