National Aeronautics and Space Administration

www.nasa.gov

14- by 22-Foot

Subsonic Tunnel

NASA’s Aeronautics Test Program

Initially named the V/STOL (vertical/short takeoff and landing) Tunnel, then the 4- by 7-Meter 

Tunnel, and finally, the 14- by 22-Foot Subsonic Tunnel (14×22) was constructed in 1970 to 

provide an improved understanding of the aerodynamics of V/STOL aircraft. Studies concentrated 

on the strong downwash generated by the V/STOL model-lift fans or jets and the interaction of 

the boundary layer with the vertical or forward-facing, propulsion-flow components. 

Today, the 14×22 assesses conventional performance for low-speed tests of powered and 

unpowered models of various fixed- and rotary-wing civil and military aircraft over a wide 

range of takeoff, landing, cruise, and high-angle-of-attack conditions. The tunnel can be easily 

reconfigured for acoustic, tethered free-flight and forced-oscillation (dynamic stability) testing, 

as well as for motor-sports studies. Investigators can choose from either closed (walls, ceiling, 

and floor) or open (floor-only) test-section arrangements.

The 14×22 is ideally suited for low-speed tests to determine high-lift 

stability and control, aerodynamic performance, rotorcraft acoustics, 

turboprop performance, and basic-wake and flow-field surveys.

An extensive modification was completed in 1984 to improve airflow 

and expand capabilities for both acoustic and rotorcraft testing. In 1999, 

an automation system and new model carts were added. Major clients 

have included the Department of Defense and aircraft manufacturers 

such as Boeing, Lockheed Martin, and Northrop Grumman.

Motor sports and vehicular tests have been conducted in cooperation 

with Old Dominion University.
M–18

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NASA’s Aeronautics Test Program www.aeronautics.nasa.gov/atp

Facility Benefits

•	 A boundary-layer removal system and moving-belt ground plane 

prevent the formation of a floor boundary layer in the test section

•	 A uniform vertical velocity distribution for ground-effects testing is 

maintained 

•	 The tunnel has a set of flow-control vanes to calibrate and sustain 

exact air velocity for low-speed testing

•	 The flow in the closed test section configuration is relatively 

uniform, with a velocity fluctuation of 0.1 percent or less

Contact Information

www.aeronautics.nasa.gov/atp

P. Frank Quinto

NASA Langley Research Center

Phone: 757–864–5068

E-mail: wte+fm_14x22@larc.nasa.gov

Facility Applications

•	 Aviation safety

•	 Subsonic fixed wing

•	 Subsonic rotor wing

Instrumentation

Strain gauge balances Six-component internal

Available corrections Interactions

Temperature effects

Attitude tares

Axes orientation

Pressure tares

Momentum (flow) tares

Angle-of-attack (AOA) 

accelerometers 

Q-Flex

Data Acquisition and Processing

Inputs Analog, digital, and electronically scanned pressure 

(ESP) system

Controller Open Architecture Data Acquisition Systems (OADAS)

Capacity/channels Analog/128, Digital/32, and ESP/2048

Dynamic data acquisition 64 channels at up to 102.4 ksps and based upon the 

VT1432b digitizer

Maximum bandwidth 46 kHz, 24 bits for a 108 dB (typical) dynamic range

Classified capability Yes

Characteristics

Test section dimensions 14.5 ft high by 21.75 ft wide by 50 ft long

Circuit length 770 ft

Area 315.4 ft2

Speed 348 ft/s

Reynolds number 0 to 2.2×106 per ft

Pressure Atmospheric

Temperature Ambient

Test gas Ambient atmosphere

Contraction area ratio 9:1

Drive power 12 000 hp