Maureen T. Kudlac and Harold F. Weaver

Glenn Research Center, Cleveland, Ohio

Mark D. Cmar

Sierra Lobo, Inc., Fremont, Ohio

NASA Plum Brook’s B–2 Test Facility: Thermal 

Vacuum and Propellant Test Facility

NASA/TM—2012-217234

December 2012
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Maureen T. Kudlac and Harold F. Weaver

Glenn Research Center, Cleveland, Ohio

Mark D. Cmar

Sierra Lobo, Inc., Fremont, Ohio

NASA Plum Brook’s B–2 Test Facility: Thermal 

Vacuum and Propellant Test Facility

NASA/TM—2012-217234

December 2012

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

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Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2012-217234 1 

NASA Plum Brook’s B–2 Test Facility: Thermal Vacuum 

and Propellant Test Facility 

Maureen T. Kudlac and Harold F. Weaver 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Mark D. Cmar 

Sierra Lobo, Inc. 

Fremont, Ohio 43420 

Abstract 

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum 

Brook Station (PBS) Spacecraft Propulsion Research Facility, commonly referred to as B–2, is NASA’s 

third largest thermal vacuum facility. It is the largest designed to store and transfer large quantities of 

liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of upper stage 

chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing 

thermal-vacuum simulation services to support testing of large lightweight structures, Cryogenic Fluid 

Management (CFM) systems, electric propulsion test programs, and other In-Space propulsion programs. 

A recently completed integrated system test demonstrated the refurbished thermal vacuum 

capabilities of the facility. The test used the modernized data acquisition and control system to monitor 

the facility. The heat sink provided a uniform temperature environment of approximately 77 K. The 

modernized infrared lamp array produced a nominal heat flux of 1.4 kW/m2

. With the lamp array and heat 

sink operating simultaneously, the thermal systems produced a heat flux pattern simulating radiation to 

space on one surface and solar exposure on the other surface. 

Introduction 

The B–2 test facility was designed in the 1960s to provide a test bed for upper stage vehicles. It is a 

high altitude facility capable of testing full scale launch vehicles in a simulated space environment. The 

facility can provide long term space simulation combined with multiple engine firings representing the 

full mission profile of an upper stage vehicle. Over the last 5 decades the core capabilities of the facility 

have been used to test a wide variety of hardware in addition to upper stages. The facility is 

systematically undergoing refurbishment and modernization to continue to meet customer needs. 

Facility Core Capabilities 

The B–2 test facility is located at Plum Brook Station, in Sandusky, Ohio. Plum Brook Station is the 

2590 hectare (6400 acre) field station of NASA Glenn Research Center. The test facilities at Plum Brook 

are separated by large distances to safely support testing of large quantities of gaseous or cryogenic 

propellants necessary for rocket engine and component testing. An artist’s rendering of the B–2 Facility is 

shown in Figure 1. 

The center of the B–2 facility is a large vertical vacuum chamber. The chamber consists of a 

cylindrical section that is 14 m (46 ft) high by 11.5 m (38 ft) topped with a hemispherical head of the 

same diameter. The lower end of the chamber has a 3.4 m (11 ft) diameter by 11.3 m (37 ft) long exhaust 

duct sealed with a high vacuum valve. Typical test article installation into the test chamber is via a hinged 

hatch at the top of the hemispherical dome using an 18,100 kg (20 ton) overhead crane. The hatch is 
NASA/TM—2012-217234 2 

Figure 1.—An artist’s rendering of the B–2 test chamber. The vacuum chamber 

is shown with the top hatch open. The LN2 vessel that feeds the heat sink is 

visible near the open top cap. The water cooled diffuser duct and spray 

chamber are shown below the vacuum chamber. The visible propellant abort 

tanks in the spray chamber protect facility/test hardware in the event of a test 

article anomaly. 

8.2 m (26.75 ft) in diameter. The nominal test article envelope is 6.7 m (22 ft) diameter by 15.8 m (52 ft) 

maximum vertical clearance. Personnel and small equipment access is available via 1.8 m (6 ft) diameter 

circular doors located at the bottom of the chamber and at 12.5 m (41 ft) above the bottom of the 

chamber. Numerous high-vacuum penetrations exist at multiple elevations for routing of fluids and 

electrical power, or signals internal to the chamber without compromising the vacuum environment. 

Vacuum levels in the 10–5 Pa (10–7 torr) are achieved using oil diffusion pumps backed by a series of 

mechanical pumps. Cold caps on the diffusion pumps are used to minimize oil back-streaming. 

Located below the vacuum chamber is a large concrete structure known as a “spray chamber”. The 

spray chamber handles the test article exhaust for engine thrust levels of 444,822 N (100,000 lb). The 

spray chamber is 20 m (67 ft) diameter by 36 m (119 ft) high. The spray chamber can be evacuated to 

approximately 1 kPa (0.15 psia) independent of the vacuum chamber using steam ejectors. The spray 
NASA/TM—2012-217234 3 

chamber is filled with 6.6 million liters (1.75 million gallons) of cooling water. During an engine firing at 

altitude conditions, the cooling water is circulated to a series of spray bars which produce a fine water 

spray to quench and condense the exhaust. Non-condensable components are exhausted via the steam 

ejectors. Cooling is also provided on the back side of the diffuser duct and to the steam ejectors. Fuel and 

oxidizer abort (dump) tanks are also located in the spray chamber and can be used to safe the facility in 

the event of a test article anomaly. 

Thermal simulation for the test article is achieved using a liquid nitrogen heat sink and an infrared 

lamp array. The interior surface of the stainless steel vacuum chamber is lined with a liquid nitrogen 

(LN2) heat sink or cold wall. The heat sink covers the entire interior of the test chamber reducing the 

internal clearance to 10.4 m (34 ft) diameter and 17 m (56 ft) high. The access hatch or top cap has a 

separate liquid nitrogen heat sink. The only portion of the chamber not having integrated heat sink 

coverage is a 6.7 m (22 ft) diameter circle on the floor level of the chamber. The heat sink consists of a 

series of finned tubes connected to an upper and lower manifold. The fins are arranged parallel to the 

chamber wall resulting in an optically dense surface. The heat sink is flooded with LN2 providing a 

background temperature of 77 K (140 °R). The heat sink is constructed of copper to optimize conduction. 

An infrared lamp array installed in the vacuum chamber provides a heat flux pattern equivalent to a 

nominal solar constant, 1.367 kW/m2

. The array is configurable and can be independently controlled by 

twelve (12) zone controllers. When fully configured, each zone contains forty-eight (48) 0.75 kW lamps 

resulting in a total array power of 432 kW. Each zone controller is rated at 50 kW yielding a system 

capacity of 600 kW. When the heat sink and infrared lamp array are used simultaneously, a test article can 

be exposed to a thermal pattern representing deep space on one surface and the solar expose on a separate 

surface. 

The test building is designed for propellant testing. Components in the building have been selected to 

be non-incendiary or are located in purged/pressurized enclosures. During propellant testing, personnel 

are evacuated from the test building. Tests are conducted from a remote control room located 777 m 

(2,550 ft) west of the test building. 

Propellants are stored in bulk outside of the test building. On-site liquid hydrogen (LH2) storage 

capacity is 128,704 L (34,000 gal). B–2’s storable fuel (fuel which is liquid at ambient temperatures) 

storage capacity is 24,605 L (6500 gal). The liquid oxygen (LO2) storage capacity is 45,425 L 

(12,000 gal). Gaseous nitrogen (GN2) and gaseous helium (GHe) are used to provide purge and 

pressurization. 

Decades of Testing 

The B–2 test facility was designed to test upper stage vehicles and engines at simulated altitude 

conditions. The size and capabilities of the thermal vacuum chamber in addition to the ability to 

simultaneously test fuels and oxidizers has pushed B–2 outside of its original mission of testing upper 

stage vehicles. 

During the development of the Centaur vehicle approximately 73 tests were performed at B–2 

(Ref. 1). Some of the Centaur development tests involved tanking and chilldown leading up to ignition 

and restart testing and finally full duration mission simulation tests. Upper stage test capabilities were 

also used during the Delta III (Ref. 2) programs in the 1990s. The B–2 vacuum chamber was also used to 

develop engine chill down techniques for both the Atlas Reliability Enhancement Program (AREP) 

(Ref. 3) and Delta III Programs (Ref. 2). Altering the chill down for the engines led to lower over board 

propellant losses leading to enhanced payload capability. 

B–2 has also been involved in development of small thrusters, payloads, and components for use in 

upper atmosphere and space environments. In small thruster test programs the facility exhaust systems are 

not used. After the vacuum chamber has reached altitude conditions, the thruster is fired for short 

durations. Due to the size of the vacuum chamber, pressures do not increase significantly. Thruster 

programs have included Pulse Detonation Rocket Engine (PDRE). Arcjet plume interaction with solar 

arrays was also studied in the vacuum chamber (Ref. 4). Ground testing of payloads in the B–2 chamber 
NASA/TM—2012-217234 4 

Figure 2.—Centaur Stage (left) and TRACER test package (right) positioned over 

B–2 Vacuum Chamber. 

has provided valuable information. The information gained by testing in a thermal vacuum chamber has 

contributed to mission successes. Sounding rocket experimental payloads that were pre-flight tested at 

B–2 to confirm operation under vacuum and to calibrate systems include Space Powered Experiments 

Aboard Rockets (SPEAR) (Ref. 5) and Excitation by Electron Deposition (EXCEDE). For similar 

reasons, balloon payloads including Transition Radiation Array for Cosmic Energetic Radiation 

(TRACER) (Ref. 6) and Cosmic Ray Electron Synchrotron Telescope (CREST) have also done pre-flight 

thermal vacuum testing. The test chamber and cold wall were used for airbag inflation tests for the Mars 

Pathfinder (Ref. 7) and Mars Exploration Rover (MER) (Ref. 8). Figure 2 shows a Centaur Stage and the 

TRACER test package positioned over the B–2 vacuum chamber. 

The B–2 chamber has also been used for non-aerospace applications such as drying personnel records 

in the 1970s by cyclically heating and evacuating the chamber. Heating was accomplished by introducing 

steam rather than LN2 into the heat sink. 

B–2 is continuously meeting with customers to discuss testing options that include tanking tests, 

simultaneous fuel/oxidizer cryogenic fluid management (CFM) tests, and engine tests. 

Facility Modernization and Refurbishments 

In 2006, an effort to systematically refurbish all major facility subsystems and ancillary infrastructure 

equipment was started (Ref. 9). The aim of the refurbishment was to modernize the facility in phases 

starting with the vacuum system and proceeding to the thermal simulation system and then the cryogenic 

propellant and exhaust systems. The facility data acquisition and controls systems have also undergone 

extensive modernization. 

The vacuum system and test chamber were completely refurbished. All vacuum pumps were 

completely rebuilt. In addition to replacing the existing instrumentation, additional health monitoring and 

diagnostic instruments were installed. The chamber was extensively leak checked and non-destructive 

evaluation was performed to verify the structural integrity of the vacuum chamber and system. The 

thermal simulation system was also refurbished. Non-destructive evaluation of the heat sink and the LN2

supply and vent lines was performed. The controllers for the infrared lamp array were replaced with state 

of the art systems. Following the completion of refurbishment of the thermal simulation system, an 

integrated systems test was conducted to demonstrate performance. 
NASA/TM—2012-217234 5 

Figure 3.—Modernized Control Room for B–2. Graphical user 

interfaces (GUI) for the programmable logic control (PLC) based 

system are visible in the foreground. Along the back wall, video 

monitors display test site camera images. The independent data 

system consoles are not shown in this view. 

The facility control system was completely replaced in 2006 with a state of the art programmable 

logic control (PLC) based system. Graphical user interfaces (GUI) are used for operations. The control 

system is used to monitor facility systems and keeps a log of key parameters. The control system was 

designed to be easily reconfigured to support specific test package requirements. Cabling between the 

control room and test facility has been replaced with a fiber optic network. Remote video monitoring of 

the test facility was also upgraded. The data acquisition system is separate from the control systems. Data 

is time synchronized with the control system using an IRIG-B protocol. The test data is digitized in a data 

room at the test facility and is immediately transmitted to data recording units located in the control room. 

The fiber optic network has been designed to minimize time delays between data acquisition at the test 

site and transmission to the control room. Currently there are 488 channels of low speed, 32 channels of 

high speed, and 64 channels of discrete input in the data system. The data system can acquire data up to 

4,000 samples per second in the low speed and up to 256,000 samples per second in high speed. Slower 

sampling rates are also achievable and are set typically at 125 samples per second. After the data has been 

recorded, it is post processed for customer review. Figure 3 shows the modern control room for B–2. 

Refurbishment of the LH2 and GHe system are on-going. Plans have been developed for the renewal 

of the LO2 and exhaust systems. 

Thermal Vacuum Integrated System Test 

For the thermal vacuum integrated system test, a simulated test article was located approximately 

3.7 m (12 ft) above the vacuum chamber floor. Three (3) zones of infrared lamps were installed. A 

vacuum level of 9×10–4 Pa was achieved rather than the rated 10–5 Pa due to a leak in a camera purge. 

During the test, heat flux equivalent to one solar constant was measured at the test article. The lamp 

arrays were operated using both open and closed loop control. Fine tuning of the heat flux was 

demonstrated by controlling the power input to the lamp arrays. The arrays were operated both with and 

without the heat sink (body and top cap) filled with LN2. When the heat sink is at 77 K, slightly more 

power is required to achieve the same heat flux at the test article. Steady state temperature readings were 
NASA/TM—2012-217234 6 

Figure 4.—In the foreground of the picture is a test article designed 

to represent the rounded wall of a tank. Visible in the background 

are 3 infrared lamp arrays. 

achieved approximately 5 hr after filling the heat sink. (It should be noted that the simulated test article 

reached steady state temperature quickly due to the lack of insulation.) See Figure 4 for a picture of the 

simulated test article installed in the vacuum chamber. 

Conclusions 

The B–2 facility was originally designed as a thermal vacuum facility to test upper stages over the 

entire operational life including engine operation at altitude conditions. Over the years, the facility has 

been used for other tests requiring vacuum, thermal vacuum, or altitude-engine operations. Strategic 

investments have been made to modernize and refurbish facility systems and infrastructure. A recently 

completed thermal vacuum integrated systems test demonstrated the successful operation of the newly 

refurbished systems. Plans for continued investment in the propellant and exhaust systems will result in a 

fully revitalized facility. 

References 

1. Grosbeck, W., Baud, K., Lacovic, R., Tabata, W., and S. Szabo, “Propulsion System Tests on A Full 

Scale Centaur Vehicle to Investigate 3-Burn Mission Capability of the D-1T Configuration,” NASA 

TM X-71511. 

2. Meyer, M., Dickens, K., Skaff, A., Cmar, M., VanMeter, M., and Haberbusch, M., “Performance of 

Spacecraft Propulsion Research Facility During Altitude Firing Tests of the Delta III Upper Stage,” 

NASA TM-1998-208477. 

3. Schuster, J., Howell, D, Lucas, S., Haberbusch, M., Gaby, J., Van Dresar, N., and Wadel, M., “Cold 

Flow Testing of Revised Engine Chilldown Methods for the Atlas Centaur,” AIAA 96-3014. 
NASA/TM—2012-217234 7 

4. Galofaro, J., Vayner, B., Hillard, G., and Chornak, M., “Thruster Plume Plasma Diagnostics: A 

Ground Chamber Experiment for a 2-Kilowatt Arcjet,” NASA TM-2005-213837. 

5. Rochefort, J., O’Connor, L., Sukys, R., Poirier, N., and Morin, R., “Instrumentation, Control, and 

Communication Systems for Sounding Rockets and Shuttle-Borne Experiments,” PL TR 91-2175. 

6. Muller, D., “Status,” TRACER home page, http://tracer.uchicago.edu/status.html, date accessed May 

13, 2011. 

7. Cadogan, D., Sandy, C., and Grahne, M., Acta Astronautica, 50, pp. 633-640 (2002). 

8. Stein, J. and Sandy, C., “Recent Developments in Inflatable Airbag Attenuation Systems for Mars 

Exploration,” AAF-061. 

9. Hill, G., Weaver, H., Kudlac, M., Evans, R., and Maloney, C., “Space Propulsion Research Facility 

(B–2) An Innovative, Multi-Purpose Test Facility,” Aerospace Testing Seminar 2011. 
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14. ABSTRACT

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Spacecraft 

Propulsion Research Facility, commonly referred to as B-2, is NASA’s third largest thermal vacuum facility. It is the largest designed to 

store and transfer large quantities of liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of upper 

stage chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation 

services to support testing of large lightweight structures, Cryogenic Fluid Management (CFM) systems, electric propulsion test programs, 

and other In-Space propulsion programs. A recently completed integrated system test demonstrated the refurbished thermal vacuum

capabilities of the facility. The test used the modernized data acquisition and control system to monitor the facility. The heat sink provided a 

uniform temperature environment of approximately 77 K. The modernized infrared lamp array produced a nominal heat flux of 1.4 kW/m2. 

With the lamp array and heat sink operating simultaneously, the thermal systems produced a heat flux pattern simulating radiation to space 

on one surface and solar exposure on the other surface. 

15. SUBJECT TERMS

Vacuum; Vacuum chamber; Solar constant; Thermal simulation; Cryogenic fluids; Heat sink; Test facility; Propellants 

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