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Hypersonic Tunnel Facility

The Hypersonic Tunnel Facility (HTF) at NASA’s Plum Brook Station located in Sandusky, OH, originally designed to test nuclear thermal rocket nozzles, is a hypersonic (Mach 5, 6, and 7) blowdown, nonvitiated freejet facility that tests large-scale hypersonic air-breathing propulsion systems.

Facility Overview

Hypersonic Tunnel Facility
Overview of the interior of the Hypersonic Tunnel Facility.

Designed to conduct research, development, and acceptance testing of hypersonic airbreathing propulsion systems, the Hypersonic Tunnel Facility (HTF) is a fully self-contained facility. Its experimental infrastructure includes a shop area for fabrication of materials for facility subsystems and assembly of customer hardware. Due to the high-energy nature of the facility, it is operated remotely from a control room approximately one-quarter mile from the actual facility.

The HTF is a blow-down, non-vitiated, free jet wind tunnel that is capable of simulating Mach 5, Mach 6, and Mach 7 true enthalpy conditions. The primary performance differentiator between the HTF and other hypersonic free jet facilities is its non-vitiated (clean) flow. Whereas traditional facilities of this type utilize a combustion process to generate high enthalpy conditions required to simulate hypersonic flows, the HTF generates these conditions by flowing nitrogen gas through a 3 MW graphite core storage heater. This heated nitrogen is then mixed with ambient temperature oxygen and ambient temperature nitrogen to yield a flow of synthetic (true composition) air at the requisite stagnation temperature. Three interchangeable nozzles are used

Hypersonic Tunnel Facility
Overview of the interior of the Hypersonic Tunnel Facility.

to establish the facility Mach number condition of 5, 6, and 7. A nominal free jet test section ‘characteristic dimension’ is the nozzle exit diameter, 42 inches for the HTF. However, the hypersonic core flow varies with Mach number. The test section length can be adjusted from 10 feet to 14 feet in length. Utilization of aeroappliances around test hardware is standard practice. A single stage steam ejector is used to exhaust the facility flow and provide altitude simulation.

The facility’s size and long run duration allow for full systems testing of large flight rated structures and propulsion systems. The facility is capable of supporting both hydrogen and hydrocarbon fueled propulsion systems. In addition to free jet testing, the use of the facility to support direct connect subsonic and supersonic combustion is currently being developed. This capability would allow for the testing of large scale combustors in a non-vitiated flow.

Quick Facts

The Heated Tube Facility at NASA GRC investigates cooling issues by simulating conditions characteristic of rocket engine thrust chambers and high speed airbreathing propulsion systems.

Name Hypersonic Tunnel Facility
Mach Number 5.0 – 7.0
Test Section 10 ft length available, expandable to 14 ft
Altitude Up to 120,000 ft
Total Pressure 1200 psig maximum
Total Temperature 3900°R maximum


Operational Features

Propellant Systems

Control Systems

Data Systems

HTF Run Conditions
Nozzle Mach 5 Mach 6 Mach 7
StagnationPressure, psia 410.070.5 1200.0144.0 1200.0430.0
StagnationTemperature, R 22002420 29653310 38303900
Mass Flow,lbs/sec 189.030.9 222.025.4 104.036.2
ThroatDiameter, in. 7.27.2 4.94.9 3.23.2
ExitDiameter, in. 42.042.0 42.042.0 42.042.0
Test Section Mach 5 Mach 6 Mach 7
StaticPressure, psia 0.740.118 0.610.071 0.330.071
StaticTemperature, R 384428 390451 412451
Altitude, ft 68,000108,000 72,000120,000 93,000120,000
Run Time, sec 103a294b 42a294b 90a180c

a – Limited by maximum stagnation temperature change of 200»F

b – Limited by steam availability at 150 psig

c – Limited by mixture and diffuser temperature limits


Hypersonic Tunnel Facility (HTF)
Facility Manager: Gerald Hill
6100 Columbus Ave., MS 5411:105
Sandusky, OH 44870

Plum Brook Station
Deputy Director: David Taylor
6100 Columbus Ave., MS 7141:112
Sandusky, OH 44870

If you are unsure about whom to contact about a specific facility question, please call our main number at 216-433-4000.

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