A Tracer Analysis for the M1002 Training Projectile 

by James Garner, Xaiogang Huang, Jason Mishock, and John Kostka 

ARL-TR-4924 September 2009 

Approved for public release; distribution is unlimited. 
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Army Research Laboratory 

Aberdeen Proving Ground, MD 21005-5066 

ARL-TR-4924 September 2009 

A Tracer Analysis for the M1002 Training Projectile 

James Garner and Xaiogang Huang 

Weapons and Materials Research Directorate, ARL 

Jason Mishock and John Kostka

PM Maneuver Ammunition Systems 

Approved for public release; distribution is unlimited. 
ii

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 

1. REPORT DATE (DD-MM-YYYY)

September 2009 

2. REPORT TYPE 

Final 

3. DATES COVERED (From - To) 

October 2006–October 2007 

4. TITLE AND SUBTITLE 

A Tracer Analysis for the M1002 Training Projectile 

5a. CONTRACT NUMBER 

5b. GRANT NUMBER 

5c. PROGRAM ELEMENT NUMBER 

6. AUTHOR(S) 

James Garner, Xaiogang Huang, Jason Mishock,* and John Kostka*

5d. PROJECT NUMBER 

AH80 

5e. TASK NUMBER 

5f. WORK UNIT NUMBER 

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

U.S. Army Research Laboratory 

ATTN: AMSRD-ARL-WMB-C 

Aberdeen Proving Ground, MD 21005-5066 

8. PERFORMING ORGANIZATION 

 REPORT NUMBER 

ARL-TR-4924 

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

Program Manger Maneuver Ammunition Systems 

Picatinny Arsenal, NJ 07806-5000 

10. SPONSOR/MONITOR’S ACRONYM(S) 

PM-MAS 

11. SPONSOR/MONITOR'S REPORT 

 NUMBER(S) 

12. DISTRIBUTION/AVAILABILITY STATEMENT 

Approved for public release; distribution is unlimited. 

13. SUPPLEMENTARY NOTES 

*

PM Maneuver Ammunition Systems, Picatinny Arsenal, NJ 07806-5000 

14. ABSTRACT 

Testing to qualify the M1002 round was conducted in FY08. The M1002 round has met its accuracy requirements as a training 

round to replace the M831A1. The present configuration achieves acceptable performance but could be improved. This report 

provides an understanding of some of the tracer’s launch conditions, which are important in determining what might be done to 

further improve tracer performance.

15. SUBJECT TERMS

tracer, M1002, projectile testing 

16. SECURITY CLASSIFICATION OF: 

17. LIMITATION 

OF ABSTRACT 

UU 

18. NUMBER 

OF PAGES 

20 

19a. NAME OF RESPONSIBLE PERSON

James Garner 

a. REPORT 

Unclassified

b. ABSTRACT 

Unclassified

c. THIS PAGE 

Unclassified

19b. TELEPHONE NUMBER (Include area code) 

410-306-0785 

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
iii

Contents 

List of Figures iv

List of Tables iv

Acknowledgments v

1. Introduction 1

2. Projectile Tracer Configuration and Propellant Properties 1

3. Finite-Element Modeling and Results 3

4. Recent Test Results 8

5. Conclusions 8

Distribution List 9 
iv

List of Figures 

Figure 1. M1002 projectile assembly cross section. .......................................................................2

Figure 2. M1002 flare cone cross section with three-pellet tracer configuration. ..........................2

Figure 3. A schematic section of the tracer cup. .............................................................................4

Figure 4. Complete bonding of pellets to cup wall. ........................................................................5

Figure 5. Stress contours allowing first pellet sliding boundary condition. ...................................5

Figure 6. Displacement and stress contours with pellets 1 and 2 sliding at the boundary..............6

Figure 7. Pellet-to-pellet interface gaps. .........................................................................................7

Figure 8. Enhanced burning configuration for tracer pellets. .........................................................8

List of Tables 

Table 1. Tracer material properties variation with temperature. ....................................................3
v

Acknowledgments 

Thanks are extended to Dipak Kamdar of ATK for insights offered from prior tracer modeling 

efforts.
vi

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1

1. Introduction 

The M1002 is the high-explosive antitank training round planned to replace the M831A1. The 

round has achieved type classification and substantially meets its requirements as a training 

round. A nagging shortcoming of tracer burnout at cold conditions was observed in a number of 

tests and merited examination as to its source. The purpose of the tracer is to allow the projectile 

trajectory to be immediately visualized so that a judgment can be made as to where the round 

impacted and if the flight was as expected. This information is essential in training scenarios as 

gunner accuracy is the skill being developed and requires instant round-to-round accuracy 

assessment by the trainee. Tracer failure for the M1002 round is defined as nonvisibility at the 

3000-m range. This normally manifests itself in premature tracer burnout (the tracer was seen to 

ignite near the muzzle but was not visible at the 3000-m location). 

The U.S. Army Research Laboratory was asked to perform finite-element analyses and materials 

characterization studies to better understand the phenomena observed in testing. Initial stress 

analyses presumed mechanical properties and were coupled with appropriate boundary 

conditions to yield results for comparison with in-flight testing and recovered test article data. 

Mechanical properties of the tracer material remain to be accomplished to establish a broader 

database on their stress-strain behavior. These data can be reinserted in analysis codes to better 

understand the range of possible effects. 

2. Projectile Tracer Configuration and Propellant Properties 

The configuration of the tracer well, the tracer material, and the interior ballistic conditions in the 

ballistic cycle are all critical to understanding the course of events and end results observed. 

Figures 1 and 2 show a projectile assembly, flare cone, and tracer cup (shown in yellow with a 

gray cap) cross sections with tracer fill material (shown in red). The gray cap and filled tracer 

cup is threaded into the projectile flare cone to form the completed projectile assembly. 

The tracer fill/burn material in the cup comprises three pellets pressed together and glued in 

place at the pellet-cup interface with an igniter layer (shown in gray) covering the third pellet. 

Ideally during the launch cycle, a protective brass diaphragm enclosing the tracer mix is broken, 

and the igniter and pellets burn in sequence forward throughout the projectile flight. Once the 

diaphragm breaks, the fill material is exposed to the base pressure and hot gasses. The effect of 

this pressure was thought to be minimal as the fill material is contained. For an incompressible 

solid, this is a believable condition, but the extent to which the fill material is incompressible is 

uncharacterized, leaving questions as to its actual behavior during the interior ballistic launch 
2

cycle. Detailed stress analyses were conducted using varying boundary conditions and pellet 

configurations to attempt to model the launch conditions and ultimately match observed test 

results. 

Figure 1. M1002 projectile assembly cross section. 

Figure 2. M1002 flare cone cross section with three-pellet tracer configuration. 
3

Premature tracer burnout raises several questions. Does the burn react to the interface between 

the pellets? Does the launch acceleration fracture the pellets? Is there benefit in a double or 

single pellet design to replace the present three-pellet design? Do cold conditions affect the 

tracer fill mechanical properties. Table 1 illustrates the change in properties under varying 

temperature conditions with the associated moduli.*

Table 1. Tracer material properties variation with temperature. 

Temperature 

(°C) 

Modulus E 

(psi) 

Shear Modulus G 

(psi) 

Ultimate Stress 

Compressive 

(psi) 

52 19,000 6333 700 

21 49,000 16,333 1700 

–32 118,000 39,333 5400 

A stress analysis is useful in understanding a possible sequence of events and relating those 

events to those observed. The properties in table 1 were supplied for modeling purposes. While 

ARL has facilities to determine propellant mechanical properties, this testing remains to be 

completed. An independent verification of the properties would improve the credibility of the 

data and thereby improve model credulity. The failure mechanism that determines ultimate 

strength was unspecified in table 1. The burning that results from a brittle catastrophic failure 

(lots of smaller particles and an increased propellant surface area) is much different than a 

buckling failure that might be more of a bend with a single fracture in the propellant grain. The 

surface area and burning properties for the latter might remain closer to its original condition. 

3. Finite-Element Modeling and Results 

A model of the tracer cup was constructed, and boundary conditions were applied using 

ABAQUS.1,2 A tracer cup model section sketch is shown in figure 3. A three-dimensional 

model of the tracer cup assembly was used to assure fidelity of the solution and contain material 

under the projectile base pressure load. The pressure seen across the nozzle of the tracer (after 

the diaphragm breaks) is greatly reduced relative to the base pressure. A scaled pressure loading 

factor of 0.2 the base pressure was selected to account for pressure reductions due to choked 

flow across the tracer nozzle and volume changes, as the projectile translates downbore, and 

_______________________ *

Shear modulus calculated: G = E/2(1+), where  = 0.499 (measured for propellant at 21 °C). 

1

ABAQUS, Inc. ABAQUS Theory Manual, version 6.6; Providence, RI, 2006. 

2

ABAQUS, Inc. ABAQUS/Standard User’s Manual, version 6.6; Providence, RI, 2006.
4

Figure 3. A schematic section of the tracer cup. 

averaged loading conditions on the tracer mix. The exact pressure exerted on the fill is 

unknown. The ABAQUS analysis code allows for sliding elements. The sliding elements 

modeled the scenario of the pellet (wall bond shearing and allowing an individual pellet to slide). 

The Von Mises stress is plotted using a scaled base pressure with perfect bonding (no sliding) of 

the pellets at the cup wall (see figure 4). Areas that are deep blue and light blue most likely do 

not fail, while other colors indicate stress levels that probably do fail. 

The realistic modeling of the sequence of events during launch is always a challenge. The model 

assumes the tracer pellet(s) and the cup wall are glued together and, in theory, they are rigid up 

to a yield stress level. Above that stress level, the material may fracture. Test data clearly 

indicate that the tracer material fractures as pieces of material are sometimes expelled. Absent is 

the effect of temperature. In the cold condition, the tracer material may be more brittle and 

therefore more inclined to fracture and propagate stress and fracture under a rapid loading. The 

following analyses use the presumption that when the stress level exceeds the shear strength of 

the pellet material, it fractures at the cup-pellet interface and becomes a sliding mass with a 

sliding surface at the pellet-cup interface. Then the next pellet (moving from top to bottom) is 

tasked with supporting the weight of the free pellet as well as its own weight under pressure. 

Figure 5 shows the case of the first pellet sliding, and figure 6 shows the shearing for a fully 

sliding tracer fill. The last pellet is unable to slide downward as its base is supported by the 

metal tracer cup. The metal tracer cup, though thin, is supported by the aluminum flare material 

and is essentially rigid.
5

100 MPa

50 

 0 

Axial Displacement & Stress

5mm

2.5 

 0 

Figure 4. Complete bonding of pellets to cup wall. 

8mm 

4 

 0 

100 MPa 

50 

 0 

Axial Displacement & Stress

Figure 5. Stress contours allowing first pellet sliding boundary condition.
6

8 mm 

4 

 0 

100 MPa

50 

 0 

Axial Displacement & Stress

Figure 6. Displacement and stress contours with pellets 1 and 2 sliding at the boundary. 

With the all-sliding boundary condition, the final result is that the tracer material becomes highly 

compressed against the base of the cup. Once the pressure is substantially released (on muzzle 

exit), the tracer material is free to slide backward (unloading) within the cup. During the 

subsequent projectile free flight, the tracer material may even be expelled unburned through the 

nozzle. 

A number of caveats are worth mentioning when comparing modeling results to results from 

live-fire testing. The tracer material properties used in the analysis are obtained at room 

temperature. The ductility of the material likely varies with temperature changes. Changes in 

ductility could and probably do result in different fracture behaviors for the tracer material, and 

this condition in turn can result in burning anomalies. Most of the anomalies in tracer 

performance have surfaced under “cold condition” firings. The tracer fracture situation is 

somewhat random as to where the fracture occurs during ignition. Whether the fracture occurs at 

the cup-pellet interface or somewhere within the pellet is unknown. Whatever the resultant 

tracer material geometry is after fracture will change the surface area for burning, and this 

greatly affects the burn progression. If the fracture, created by the launch pressure, results in a 

substantial gap (say between two pellets) within the tracer fill, it is possible the burn progression 

does not bridge that gap, and the tracer burns out prematurely leaving unburned pellets. 

Recovered projectiles have shown evidence of unburned material. The burn rate of a highly 
7

compressed tracer material is another question that logically arises. The mechanical compressive 

stress wave from the pressure load exceeds the burn progression rate so that mechanical effects 

will occur initially. If the tracer material remains compressed after being subjected to the launch 

loads (a plastic deformation), the burning rate of a compressed material is unknown as well. 

How the tracer fill material ages is yet another variable. If the fill material somehow absorbs 

water, or if any outgassing of the material has taken place, the material burn properties may 

again be affected. 

A simple scenario may be most applicable. Pellet gaps that are pre-existing (coming from an 

assembly process) could also explain the premature burnout. These could be created by the inert 

particles or glue residue at the pellet (pellet interfaces as shown in figure 7). 

Figure 7. Pellet-to-pellet interface gaps. 

It is presumed that care is taken to eliminate such gaps. But if assembly gaps are the problem, at 

least two solutions could be considered. The first is a single pellet design that eliminates the 

interfaces entirely. The production problems that would be introduced by this suggestion are 

uncertain. A question of homogeneity for a larger volume pellet might also be at issue. The 

second solution is to maintain the three-pellet geometry but have a center perforation in each 

pellet such that the combusting high-pressure gas could reach all of the pellets more or less 

simultaneously and better assure complete combustion of the fill material. This is shown in 

figure 8. The burning rate of this configuration would have to be examined to verify its 

functioning for ranges >3 km. The center hole (perforation) diameter could be adjusted to 

produce the burn time (flight time) required yet still promote complete tracer 

function/combustion. While this solution is classed as a solution, it may create processing or 

fabrication challenges. These would have to be evaluated in light of the anticipated 

improvement in tracer function.
8

Figure 8. Enhanced burning configuration for tracer pellets. 

4. Recent Test Results 

Fortunately, the most recent M1002 testing has demonstrated that the tracer material is 

performing as expected even at the cold temperatures. The manufacturing processes have not 

changed nor have the material constituents changed for the tracer; the performance improvement, 

while welcome, is not completely understood. 

5. Conclusions 

An M1002 tracer modeling capability exists to examine the response of the tracer material 

configurations under loading. This capability offers significant insight into possible in-bore 

mechanical behaviors of the tracer design and can be used in assessing future configurations of 

double or single pellet fills. These analyses are only as reliable as the tracer material properties 

that are used. These analyses highlight the need for material properties that reflect the state of 

the tracer material during launch. 
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