Scott R. Thomas and Jinho Lee

Glenn Research Center, Cleveland, Ohio

John W. Stephens, Robert W. Hostler, Jr., and William D. Von Kamp

Plum Brook Operations Support Group, Sandusky, Ohio

The Mothball, Sustainment, and Proposed

Reactivation of the Hypersonic Tunnel

Facility (HTF) at NASA Glenn Research Center

Plum Brook Station

NASA/TM—2010-216936

December 2010

AIAA–2010–4533
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Scott R. Thomas and Jinho Lee

Glenn Research Center, Cleveland, Ohio

John W. Stephens, Robert W. Hostler, Jr., and William D. Von Kamp

Plum Brook Operations Support Group, Sandusky, Ohio

The Mothball, Sustainment, and Proposed

Reactivation of the Hypersonic Tunnel

Facility (HTF) at NASA Glenn Research Center

Plum Brook Station

NASA/TM—2010-216936

December 2010

AIAA–2010–4533

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

27th Aerodynamic Measurement Technology and Ground Testing Conference

sponsored by the American Institute of Aeronautics and Astronautics

Chicago, Illinois, June 28 to July 1, 2010
Available from

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Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2010-216936 1 

The Mothball, Sustainment, and Proposed Reactivation of the 

Hypersonic Tunnel Facility (HTF) at NASA Glenn 

Research Center Plum Brook Station

Scott R. Thomas and Jinho Lee 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

John W. Stephens, Robert W. Hostler, Jr., and William D. Von Kamp 

Plum Brook Operations Support Group 

Sandusky, Ohio 44870 

Abstract 

The Hypersonic Tunnel Facility (HTF) located at the NASA Glenn Research Center’s Plum Brook 

Station in Sandusky, Ohio, is the nation’s only large-scale, non-vitiated, hypersonic propulsion test 

facility. The HTF, with its 4-story graphite induction heater, is capable of duplicating Mach 5, 6, and 7 

flight conditions. This unique propulsion system test facility has experienced several standby and 

reactivation cycles. The intent of the paper is to overview the HTF capabilities to the propulsion 

community, present the current status of HTF, and share the lessons learned from putting a large-scale 

facility into mothball status for a later restart. 

Introduction 

The NASA Glenn Research Center Hypersonic Tunnel Facility (HTF) is one of four large-scale test 

facilities located on the 6400 acre campus of Plum Brook Station in Sandusky, Ohio. The HTF is a largescale, government-controlled property which is remotely located with large exclusion zones that are ideal 

for safely testing propulsion systems at the extreme conditions typical of hypersonic flight. The HTF is a 

blow-down, non-vitiated, free-jet facility capable of simulating up to Mach 7 flight conditions where the 

stagnation temperatures reach up to 3500 F. The HTF is unique because the synthetic air generation 

process provides the enthalpy required for up to Mach 7 simulation with non-vitiated flow. Major features 

of the HTF are shown in Figure 1 and an aerial view in Figure 2. 

Central to the facility’s unique method of manufacturing synthetic air is an inductively-heated, 

graphite-core storage heater. During typical facility operation, the graphite-core storage heater is 

systematically brought up to the required operating temperature (up to 4000 F) using electrically 

powered induction coils. Once at temperature, gaseous nitrogen is passed through the heater. After 

heating, this hot nitrogen gas is mixed with unheated nitrogen and oxygen in the correct proportion to 

simulate air at the desired enthalpy. The facility can deliver this synthetic air at up to 220 lb/sec. 

The HTF was originally configured and has been utilized in a free-jet test mode. Three water-cooled, 

axisymmetric free-jet nozzles are available with exit Mach numbers of 5, 6, and 7. Each nozzle has a 

42-in. diameter exit plane, and provides high-quality, free-jet flow into the test chamber. In 2006, a directconnect testing mode was added to the facility which included the capability to accurately measure and 

deliver synthetic air flows down to approximately 50 lb/s. The free-jet and direct-connect hardware both 

utilize the same ancillary facility systems, therefore, minimizing the time required to change between the 

two operating modes.

The free-jet facility nozzles and the HTF test chamber can accommodate models up to 12 ft. in length 

and up to 2 ft. in diameter. The facility’s graphite induction heater can supply nitrogen flows, up to 

130 lb/s at 4000 F and 1200 psia. Gaseous nitrogen is supplied from the 5000 psia, 750,000 standard 
NASA/TM—2010-216936 2 

cubic feet (scf) railcar shown in Figure 3. Hot nitrogen from the heater flows through graphite-lined, 

water-cooled piping, through the Radiation Shutter Valve (used to isolate the test cabin from the hot 

graphite heater), and into a water-cooled mixer. The Radiation Shutter Valve seals off the storage heater 

between test runs, allowing a positive pressure nitrogen or helium purge to be maintained on the heater. In 

the mixer section, oxygen and diluent nitrogen for temperature control are mixed with the hot nitrogen to 

produce a test condition with true temperature, composition, and altitude simulation. Ambient gaseous 

oxygen is supplied from the array of six vessels shown in Figure 4. A steam ejector system with a flow of 

540 lb/s of 150 psig saturated steam provides the appropriate altitude condition in the test cell. The 

altitude limit is approximately 120,000 ft. Typical run times vary with test condition and typically range 

from 1 to 5 min. The facility hot train is shown in Figure 5. One of the free-jet nozzles is shown in 

Figure 6. 

Several major test programs were conducted in the HTF since it was built and configured as a 

hypersonic aero-propulsion facility. The Hypersonic Research Engine (HRE) was tested at Mach 5, 6, and 

7 from 1972 to 1974 (Ref. 1). The HRE program was one of the earliest demonstrations of scramjet 

performance in a ground-based facility. In 1974, following the HRE program, the HTF was mothballed 

along with the majority of the facilities at the NASA GRC Plum Brook Station. Documentation of 

inspections from that time show the facility, when put into a mothball status, was already in need of repair 

and refurbishment following extensive use during the HRE program. 

A decision to reactivate HTF was made in the late 1980s. From 1990 to 1994 the facility was restored 

and a series of integrated systems tests (ISTs) were conducted in 1994 and 1995 (Ref. 2). This reactivation 

effort brought the graphite heater and all other facility systems back to a fully operational status. 

A propulsion test of the Strutjet Engine, a Rocket-Based Combined Cycle (RBCC) engine system, 

was conducted in 1996 (Ref. 3). The Strutjet engine is a ram/scram combustor with integrated rocket 

thrusters. Originally the testing was planned using both hydrocarbon (JP-10) and then also hypergolic 

fuels. Forty-one tests of the engine were completed using JP-10 fuel before this activity ended abruptly 

with a failure of the Radiation Shutter Valve. 

The facility, including the graphite heater, was rebuilt and restored from 1997 to 2000 (Ref. 4). The 

failure in 1996 of the Radiation Shutter Valve had resulted in substantial facility damage, necessitating 

the restoration project. This project was completed late 1999, culminating in another series of IST’s in 

early 2000. Over the two and a half year rehabilitation effort, significant improvements were implemented 

at the HTF to improve productivity and reliability, as well as to ensure personnel safety. 

In 2002, testing of a Department of Energy (DOE) Reheater Combustor concept was conducted at 

HTF. The test did not require the graphite heater, but took advantage of many of the ancillary facility 

systems. The free-jet hardware was stored locally while the chamber and gas systems were modified and 

utilized for the DOE test program. Following the program, the facility was restored to the free-jet 

configuration. 

In 2003, HTF was selected to test a large-scale Rocket-Based Combined Cycle (RBCC) directconnect combustor experiment for the NASA Next Generation Launch Technology (NGLT) program’s 

Integrated System Test of an Air Breathing Rocket (ISTAR) Project (Ref. 5). From 2004 to 2006 

significant facility enhancements, including the conversion to the direct-connect operating mode, were 

completed in preparation for this test. A major upgrade was made to the facility fuel capability with the 

addition of an endothermic hydrocarbon fuel reactor and supporting equipment capable of simulating the 

heated and cracked fuel conditions of RBCC engine environments. This effort included the addition of a 

6 MW substation, new steam generators to replace the World War 2 vintage boilers, and modernization of 

the flow control computer. The free-jet hardware (nozzles and aerodynamic appliances) were removed 

and stored locally to make room for installation of the direct-connect hardware. The direct-connect 

hardware included an adaptive nozzle, a calorimeter duct, necessary transition hardware, and a test article 

simulator for IST runs. 
NASA/TM—2010-216936 3 

In 2006 the NGLT program and ISTAR project were cancelled and this test was never conducted. 

Cancellation of the NGLT program resulted in a limited national hypersonic testing requirement. This led 

to the decision in 2007 by the NASA Aeronautics Research Mission Directorate (ARMD) along with the 

Aeronautics Test Program (ATP) to conduct an orderly shutdown and mothball of the HTF and associated 

assets. 

The main focus of this paper is to describe the following: 1) how the HTF mothball task was 

implemented to preserve and protect the facility for future use, 2) on-going efforts underway to monitor 

and maintain the facility to prevent deterioration of vital assets, and 3) the scope of work required for 

reactivation of the facility. Currently, the HTF heater and high-pressure supply systems are in excellent 

condition. A nominal level of effort, similar to that of any other large-scale facility, would be required to 

return HTF to an operational status. However, if the facility remains in mothball status a long period of 

time there will be additional challenges involved. 

Mothball of the Hypersonic Tunnel Facility 

Background 

A carefully thought-out mothball plan was prepared and executed by the test team at Plum Brook 

Station in order to minimize the level of effort required by future programs to reactivate the facility. Much 

of the experience necessary to put the facility into a mothball status was already in place at Plum Brook 

Station from the 1974 shutdown. The lessons-learned from this experience were leveraged as the basis of 

the current mothball activity. The crew worked with the realization that controlled air breathing 

hypersonic flight is the final frontier in aeronautical sciences and will, again, become a national priority. 

Therefore, every effort was made to safe guard the facility and its assets for future use. Such facilities are 

at higher risk for extended down times, as was experienced even at HTF following the Radiation Shutter 

Valve failure in 1996. It was also recognized by NASA that the cadre of facilities comparable to HTF is 

extremely limited. In addition, as a nation, it may not make fiscal sense to build a new facility with this 

type of capability in the time frame generally required (at least in recent history) to support high priority 

national hypersonic initiatives. Therefore, mothballing and preserving HTF was, and still is, in the best 

interest for the nation. 

Planning of Mothball Task 

The mothball of the Hypersonic Tunnel Facility was planned and completed in calendar year 2007. 

The Plum Brook team developed a plan and executed an orderly shutdown of the facility, where much of 

the 1974 lessons-learned information was incorporated to preserve this capability for the future. The 

current mothball process assumed that the facility would be in a mothball status for a 10 year period or 

longer. The team used NASA Procedural Requirements, NPR 8800.15A, Chapter 3.9.4 (see Appendix A) 

as the primary basis for this process. 

Elements of the Mothball Task 

Tasks performed to put HTF into a mothball status are summarized in this section. It was assumed 

that the facility would be in this status for a period of ten years and that the essential systems would be 

preserved or put into protective storage. It was also assumed that there would be some level of 

sustainment activity following the completion of the mothball task in order to provide periodic 

inspections as well as maintenance, as needed. In addition it was recognized that key personal from the 

current facility team may not be available to support future reactivation and operation of HTF or that the 

current personal would be so far removed from HTF such that retraining in the facility systems would be 
NASA/TM—2010-216936 4 

required prior to any future testing. Therefore, the current mothball activities included archival 

documentation elements that will help with future facility endeavors. These assumptions lead the 

following activities to protect and to preserve the essential HTF assets. 

1) Weather-protected facility and buildings: All lower windows were covered with painted 

plywood to protect the glass and provide additional security. The upper windows were sealed and 

screens were checked and repaired. Screens, netting, and sealant were used to protect against 

weather and prevent pests from entering the facility. All penetrations into the buildings were 

sealed including open pipes, vents, the ejector, and entrance ways. The exterior sluice was 

defoliated and cleared of sediment and debris. Ditches were re-graded to insure proper drainage. 

The outside terminal boxes were cleaned and all seals were verified. 

2) Cleanliness maintained in the vital systems: Preservation of the HTF induction heater and the 

gaseous oxygen system (vessels and piping) was a priority during the mothballing of HTF. A 

flow through purge system was designed to supply low pressure gaseous nitrogen to the induction 

heater and the gaseous oxygen system. Nitrogen gas can be supplied from either a tube trailer or 

the nitrogen railcar. The system receives the full pressure from the supply source (up to 2400 psig 

from a tube trailer or up to 4200 psig from the railcar) and reduces pressure to the desired level. 

The oxygen system is purged at a delivery pressure up to 25 psig, with 5 psig nominal. This 

reduction station includes a back pressure regulator and pressure relief valve. The back pressure 

regulator allows a soft venting of the system and vessels when the system is exposed to heating 

during periods of high solar exposure. The graphite induction heater is purged at a nominal 

pressure of 10 in. of water column. This purge system was extensively tested to assure very 

minimal leakage would occur in the future from both the heater vessel and the gaseous oxygen 

system. 

The Radiation Shutter Valve was hydraulically moved to the open position and locked into 

place. A bypass system was put in place around this valve to ensure that it would not be over 

pressurized by the flow through purge system. The high-pressure relief valve on the graphite 

heater was removed and stored. The line was blanked to eliminate leaks and contamination. 

3) Water pipes and tanks: The cooling systems were drained to prevent damage to the systems 

from extended periods of extreme cold and from contamination. The HTF cooling system consists 

of a 20,000 gal storage tank shown in Figure 7 used in the low pressure cooling of the heater, 

Radiation Shutter Valve and portions of the synthetic air delivery system (Hot Train). The three 

6,000 gal storage tanks shown in Figure 8 are used in the nozzle, engine, and mixer cooling 

systems. All of the tanks were drained and dried and the lowest points in the system were used to 

verify the systems had been drained. A Lockout/Tagout process was implemented to prevent 

inadvertent activation of the internal heaters. On the 20,000 gal tank, all of the waterlogged, 

deteriorating insulation was removed and the structural parts were cleaned and painted as needed.

All of the rotating machinery in the facility, both electric-driven and diesel engine-driven, 

were drained, dried and stored in the facility pump house building. 

The demineralized water system, based on a Reverse Osmosis (RO) unit, was put into longterm storage. This equipment was conditioned for a long-term storage period by injecting glycerin 

throughout the unit to prevent the growth of bacteria and to preserve the filter membranes. 

4) Facility Crane: The Shepard-Niles facility crane was put into a standby state according to the 

1974 document and with concurrence of the manufacturer. All gear boxes on the crane were 

drained and refilled with preservative oil. After refilling all gear boxes with preservative oil, the 

crane bridge and trolley were fully operated and parked. The hoist hook was lowered to the floor 

and raised to its Full-Up position. The movements were performed in an effort to distribute a coat 

 
NASA/TM—2010-216936 5 

of the preservative oil throughout each gear box. Finally, Lockout/Tagout procedures were applied to 

the crane power supply and a notice was installed on the crane control pendant that it was not to be 

used before refilling the gear boxes with normal lubricant.

5) Consolidation of HTF Support Assets: There are substantial assets associated with the facility 

including spare equipment and materials, facility hardware, assembly fixtures, tools, machines, 

facility nozzles, research hardware, electronics hardware, and computer equipment. Much of the 

HTF assets were stored throughout a variety of Plum Brook Station sites and warehouse buildings 

on an informal basis prior to the mothball effort. While the active facility staff knew where this 

equipment was located and was able to collect it as needed, loss of active staff will cause some of 

these informal arrangements to get lost with time. Therefore assets at the various sites around 

Plum Brook Station, some at risk for being excessed or discarded, were gathered into centralized, 

controlled locations. These HTF assets were documented and stored for the future facility staff. 

The facility tools, equipment, and hardware were placed in cabinets, toolboxes, or crates and 

relocated into storage bunkers on Plum Brook Station. Note that valuable equipment, tools, and 

machines for which other facilities had a critical need were loaned out with documented 

agreements for the return or replacement of these items. Electronics hardware and computers 

were removed, crated, and stored in the facility (including programmable logic controllers 

(PLC’s), controls computers, data acquisition system, pressure transducers, heater vessel moisture 

detector, heater vessel oxygen analyzer, a servo valve actuator, and printers). Spare hardware and 

materials from the various sites around Plum Brook Station included graphite heater silicon tiles, 

steel for the Radiation Shutter Valve, ladder racks for cabling, a large variety of stainless steel 

piping, fittings, and facility-specific flange blanks. The three facility contoured nozzles and all 

corresponding diluents flanges were also stored in the facility or in another environmentally 

controlled storage building at Plum Brook Station. These are vital for free-jet testing and are 

exceedingly complex and valuable hardware that would be very difficult to replace. 

6) Hydrocarbon Fuel Heater Loaned to NASA Langley Research Center: A new endothermic 

fuel heater system was installed in the HTF facility in 2005 in support of the ISTAR DirectConnect Combustor Experiment. This heater is capable of conditioning liquid hydrocarbon fuels 

to replicate the conditions of a flight engine heat exchanger in both temperature and composition. 

This system uses electrical power to cause an endothermic reaction of the hydrocarbon fuel; there 

are four similar fuel heaters in service in the United States. The HTF heater incorporated the best 

features and improvements from the other systems and is the largest in terms of fuel flow 

capacity.

At the request of NASA headquarters leadership, the NASA GRC HTF hydrocarbon fuel 

heater was loaned to NASA Langley for use at the 8-ft High Temperature Tunnel (8 ft HTT). 

Specifically the following components were staged at the HTF and shipped to LaRC in 

September 2007: electrical power switch, the six 1-MW DC power converters, the fuel 

distribution valve pallet, the fuel heater coil pallet, spare inconel tubing and fittings, the DC 

feeder cables, the control skid for the fuel distribution panel, and all of the miscellaneous spare 

components for the system. This hardware remains an HTF asset but has been temporarily 

installed and validated at the 8 ft HTT. This hardware has been adapted to some degree for 

integration into the 8 ft HTT. However, it should be relatively straight forward to relocate this 

system back to HTF when required. 

7) Safety and Security: It was recognized that once the facility was in mothball status it would be 

unstaffed and personnel would only be on-site periodically for the monthly safety walk-through 

or to perform maintenance/housekeeping if required. Access to the facility is limited to 

management and emergency personnel. There is an active security system in place at HTF which 

includes a surveillance video monitored by the security personnel. An access list of authorized 
NASA/TM—2010-216936 6 

personnel is maintained by Plum Brook Station security and only these individuals will be able to 

scan in (badge swipe) to access the facility and records of access will be retained. The plywood 

covering all first floor windows as previously discussed also provides added security. Hazardous 

chemicals were removed from the facility. All paper, cardboard, and other potential fire hazards 

were removed from the facility. The facility was cleared of office supplies and non-essential 

documents. 

8) Preservation of Corporate Knowledge: As discussed earlier, it was assumed that HTF would 

remain in a mothball status for 10 years or more. It is likely that many of the current key 

personnel would be unavailable to support future facility reactivation and operation. Therefore, it 

was important to preserve this corporate knowledge by making sure that facility drawings, design 

documents, operating manuals and check lists, safety information, inventory lists, historical 

documents and information, and test reports were properly archived. During the mothball activity, 

all facility computer hard drives were imaged to compact disks. Facility drawings and papers 

were located to an HTF library area in the Plum Brook Station main office building. Facility 

drawings were also scanned into a centrally controlled electronic database.

Sustainment Activities 

There has been a modest level of effort focused on facility sustainment (i.e., preserving and 

protecting) since the completion of the mothball activity in 2007. On a daily basis, station security 

personnel drive by the facility looking for any obvious problems. The heating system boiler has been 

maintained and the heat has been kept at a low setting to minimize any issues resulting from freezing 

temperatures or thermal cycling. There are periodic (monthly) checks and walkthroughs of the facility and 

buildings to identify any issues/problems. Inspections are made for any damage, leaks, or pest infiltration. 

The integrity of the nitrogen purge system is verified weekly by checking the nitrogen pressure and the 

supply trailer is changed out (or rail car recharged) when needed. The integrity of the screens and banding 

(preventing pest infiltration) are checked quarterly. Any repairs identified as needed are implemented as 

soon as possible. Repairs to date include replacement of the service air compressor, replacement of a 

failed relief valve on the hot water tank, and mitigation of a water line leak between the boiler house and 

the facility shop building. Grounds maintenance and janitorial services are also provided. This includes 

lawn mowing, snow removal, defoliation of stone and road surfaces; as well as dredging and re-grading 

the ditches annually. It is critical to maintain the exterior grounds at the facility to make sure there is 

adequate drainage and no back-up of water, snow, or ice into the facility. 

Tasks Required for HTF Reactivation 

The mothball activity as described has prepared HTF and its associated assets (including the graphite 

heater assembly and vessel, storage pressure vessels, synthetic air systems, tunnel circuit, test cabin, 

diffuser and exhauster) to be stored in the best-possible, documented, and known state. Never the less, 

significant work will be required to reactivate and bring HTF back to safe and reliable operation after this 

extended down time. Various screens, the plywood boards, and plating will be removed. The new facility 

operations crew will need to carefully and thoroughly review the facility drawings, design documents, 

operating manuals and check lists, safety information, inventory lists, historical documents and 

information, and test reports. This operations crew will also have to undergo significant training to 

operate the various HTF systems. 

The graphite heater assembly and its many ancillary support systems are nearly “new” since only 

limited testing, at relatively benign conditions, has been conducted since the facility restoration/rebuild 

was completed in 2000. The graphite heater assembly and vessel will be validated to verify the integrity 

of the cooling coils as well as no leakage from the vessel. The desired facility hot train, diluent flange, 

and nozzle configuration (free-jet or direct-connect) will be installed and checked for integrity. Most of 
NASA/TM—2010-216936 7 

the pressure vessels, propellant systems, and water systems will have to be recertified by the NASA 

Glenn Research Center Pressure Systems Office before operation. The recertification effort will include 

the graphite heater pressure vessel, the nitrogen rail car, the six oxygen supply bottles, the oxygen supply 

system, the nitrogen supply system, and the water supply systems. 

The water systems will be brought back into service by reinstalling the rebuilt pumps and filling the 

supply tanks. The facility hydraulic system will be validated and operated. The synthetic air supply 

system including the nitrogen rail car and the oxygen bottles will be charged to working pressure. All 

pumps, both electrical and diesel, will be disassembled, rebuilt, reinstalled, and made operational. The 

synthetic air system components including valves, regulators, check valves, and flow meters will have to 

be validated and potentially rebuilt. Much of the electronics and computer equipment will be obsolete and 

will need to be replaced and reprogrammed. The useable electronics equipment will have to be validated 

and recalibrated. The facility crane may have to be disassembled and rebuilt. The facility tools, machines, 

and equipment will have to be moved back into the shop building. 

It is estimated that an overall reactivation effort will require about a year. The graphite heater will be 

operated and validated; then a facility integrated systems test series will be conducted. The HTF test team 

and the NASA Plum Brook leadership believe that this facility has unique potential and value as the only 

“clean air” high Mach number capability in the nation. The team remains enthusiastic and prepared to 

bring HTF back into service whenever the facility is needed. 

Realities of Mothball Activity 

There were direct costs associated with the mothball task and there will be direct costs required to 

reactivate HTF. There are also intangible costs associated with idling a test facility. First, there is a loss of 

experience and expertise since many (most or all) key individuals will have moved to other projects or 

locations. The status of the facility in the test community is negatively impacted and the likelihood of the 

facility being selected for any future project is appreciably lower. The rapid evolution of electronics and 

computer systems necessitate the re-scope and installation of new data and controls systems as part of any 

restart effort. This includes a substantial amount of work needed to reassemble, checkout, reprogram, and 

recalibrate all the collective HTF systems. Most of these activities are typical of any new facility or test 

program. Therefore, the efforts and resources which will be required to bring HTF back into operation 

remain competitive with any effort to bring a new facility on-line. The effort will continue to grow in scope 

the longer the facility remains dormant, however, the infrastructure and vital systems will remain intact. 

Summary 

Throughout history, hypersonics research has experienced cycles where there are periods of intense 

activity followed by periods of little activity. In the early 1970s the Hypersonic Tunnel Facility (HTF) 

was configured to support the ground testing of the Hypersonic Research Engine (HRE). The HRE test 

provided an early demonstration of a supersonic combustion ramjet (Scramjet) concept. A rapid decline in 

hypersonics research followed not long after the HRE program and the HTF was mothballed for the first 

time in 1974. The facility was reactivated in 1990 on the footsteps of the National Aerospace Plane 

initiative. However, lack of maintenance and upkeep over the years led to a longer reactivation process 

than originally envisioned. Once reactivated, the facility was again used for hypersonic propulsion testing. 

This testing ended abruptly with the Radiation Shutter Valve failure in 1996. Following that failure, the 

graphite heater and many facility components were rebuilt. The current graphite heater system has 

experienced very little use at relatively benign conditions, therefore, the facility heater remains in 

excellent condition today. 

In 2007, NASA elected to place the facility in a preserved mothball status to support future programs 

and projects. Lessons learned from the 1974 experience were directly applied to the 2007 mothballing 

process. The infrastructure is in good condition; all facility equipment is organized, inventoried, and put 

into protective storage; and all facility documentation has been brought up to date and preserved in an 
NASA/TM—2010-216936 8 

HTF library. This process ensures that future reactivation will be much more efficient than the previous 

experiences and that HTF remains available to support new projects. The scope of effort required for 

reactivation is not insignificant but is typical of a large-scale facility. The primary infrastructure and vital 

systems remain intact and protected. The team is confident that a reactivation will be accomplished 

efficiently and HTF will be again utilized for hypersonic propulsion testing in the future. 

   
NASA/TM—2010-216936 9 

Appendix A.—NASA Procedural Requirements, 

NPR 8800.15A, Chapter 3.9.4 

3.9.4. Mothballed. A condition where a facility has been deactivated and appropriate maintenance 

measures have been taken to prevent deterioration of its vital or essential systems or placed in 

protective storage. Higher first year costs would be expected because of preparations for mothballing, 

but future annual costs should be significantly lower due to reduced maintenance and repair 

requirements. Total time to deactivate and then to reactivate the facility, including the mothballed 

period, is expected to exceed 12 months. 

3.9.4.1. Utility systems and collateral equipment have been shut down and properly prepared for long 

term inactivation without significant deterioration. Selected systems should be kept in operation and 

inspected, such as cathodic protection systems. 

3.9.4.2. Facility interior has appropriate environmental control to prevent significant deterioration. 

3.9.4.3. The facility exterior envelope is inspected on a planned basis and work is accomplished as 

required to maintain the integrity of the exterior shell from the elements. The exterior of the facility 

shall also be kept in an aesthetically acceptable condition. 
NASA/TM—2010-216936 10 

References 

1. Andrews, Earl H.; and Mackley, Ernest A.: NASA’s Hypersonic Research Engine Project: A Review. 

NASA TM-107759, October 1994. 

2. Thomas, Scott R.; Trefny, Charles J.; and Pack, William D.: Operating Capability and Current Status 

of the Reactivated NASA Lewis Research Center Hypersonic Tunnel Facility. AIAA-95-6146, 

April 1995, (NASA TM-106808). 

3. Thomas, Scott R.; Perkins, H. Douglas; and Trefny, Charles J.: Mach 5 to 7 Performance Evaluation 

of a Rocket Based Combined Cycle Propulsion System at NASA LeRC HTF. NASA TM-107376, 

December 1996. 

4. Woodling, Mark A.: Restoration of the Hypersonic Tunnel Facility at NASA Glenn Research Center, 

Plum Brook Station. NASA/TM—2000-209930, March 2000. 

5. Lee, Jinho; and Krivanek, Thomas M.: Design and Fabrication of the ISTAR Direct-Connect 

Combustor Experiment at the NASA Hypersonic Tunnel Facility. NASA/TM—2005-213432, 

February 2005. 
NASA/TM—2010-216936 11 

Figure 1.—HTF layout and support systems. 

Figure 2.—Aerial view of the Hypersonic Tunnel Facility. 
NASA/TM—2010-216936 12 

Figure 3.—HTF facility railcar providing gaseous nitrogen supply. 

Figure 4.—HTF oxygen supply vessels. 
NASA/TM—2010-216936 13 

Figure 5.—Facility hot train supplied with hot nitrogen by graphite heater 

below floor. 

Figure 6.—HTF free-jet nozzle. 
NASA/TM—2010-216936 14 

Figure 7.—Low pressure system cooling water supply tank 

(20,000 gal capacity). 

Figure 8.—High pressure system cooling water supply tanks (6000 gal each).
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1. REPORT DATE (DD-MM-YYYY)

01-12-2010 

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Technical Memorandum 

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4. TITLE AND SUBTITLE

The Mothball, Sustainment, and Proposed Reactivation of the Hypersonic Tunnel Facility 

(HTF) at NASA Glenn Research Center Plum Brook Station 

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Thomas, Scott, R.; Lee, Jinho; Stephens, John, W.; Hostler, Robert, W., Jr.; Von Kamp, 

William, D. 

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WBS 599489.02.07.03.07.01 

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National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

Cleveland, Ohio 44135-3191 

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E-17540 

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Subject Category: 09 

Available electronically at http://gltrs.grc.nasa.gov 

This publication is available from the NASA Center for AeroSpace Information, 443-757-5802

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14. ABSTRACT

The Hypersonic Tunnel Facility (HTF) located at the NASA Glenn Research Center’s Plum Brook Station in Sandusky, Ohio, is the nation’s 

only large-scale, non-vitiated, hypersonic propulsion test facility. The HTF, with its 4-story graphite induction heater, is capable of 

duplicating Mach 5, 6, and 7 flight conditions. This unique propulsion system test facility has experienced several standby and reactivation 

cycles. The intent of the paper is to overview the HTF capabilities to the propulsion community, present the current status of HTF, and share 

the lessons learned from putting a large-scale facility into mothball status for a later restart.

15. SUBJECT TERMS

Hypersonic wind tunnels 

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