[441] Langley Memorial Aeronautical Laboratory (in July 1948, "Memorial" was dropped) was located at Langley Field in Elizabeth City County, Virginia, just north of the town of Hampton and some 100 miles south of Washington, D.C. By 1958, the lab occupied 773 acres divided into two areas by the runways of Langley Air Force Base. The original east area consisted of 23 acres, which the NACA used under War Department permit. The west area, developed in the early 1940s, consisted of 750 acres, 430 owned by the NACA and 320 by the army (later, by the air force). Runways, some utilities, and other facilities were used by the NACA and the military jointly.

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[442] The success enjoyed by NACA Langley as a research organization depended in large measure on the creative design and use of a variety of experimental equipment. This equipment included towing tanks (NACA Tank No. 1, operational 1931; Tank No. 2, operational 1942); a seaplane impact basin (1942); aircraft engine (1934), structures (1940), loads (1945), and instruments (1946) research laboratories; a helicopter apparatus (1944); and landing loads track (1955). By far the predominant type of facility, however, was the wind tunnel.

The following is a digest of the major research facilities at Langley in chronological order of their coming on line. Design features are summarized, as well as the purpose, cost, major modifications, and disposition of the equipment. Whenever possible, key members of the facility design teams are identified. Different NACA employees offer firsthand insights into the significance of the facilities.

The sources for this appendix are: Langley (Memorial) Aeronautical Laboratory building cost schedules, 1942-1958, (copies in LaRC Historical Archives); "Characteristics of Major Active Wind Tunnels at the Langley Research Center," NASA TM X-1130 (Washington, 1965); Alex Roland, Model Research, appendix E; Donald D. Baals and William R. Corliss, Wind Tunnels of NASA, NASA SP-440 (Washington, 1981); George W. Gray, Frontiers of Flight: The Story of NACA Research (New York, 1948), pp. 34-62; other sources as named and quoted below in specific cases.

Purpose: To give NACA engineers some fast firsthand experience with a proven tunnel design and to inaugurate in-house aerodynamic testing of scale models for comparison with full-scale, free-flight results.

Initial cost: $38,000

Circuit and pressure: Nonreturn, atmospheric Test section: 5' diameter, closed throat

Drive system: Fan; 200-HP electric motor Maximum speed: 89 MPH

Special equipment: None

Key members of design team: Edward P. Warner and Frederick H. Norton

Authorized: 6 October 1917

Operational: 11 June 1920

Significance: "With relatively minor changes, the first Langley wind tunnel was patterned after one located at the British National Physical Laboratory. [The tunnel] was therefore obsolete when it was built .... From the standpoint of research, tunnel no. 1 was relatively unproductive." Baals and Corliss, Wind Tunnels of NASA, pp. 14-15.

Disposition: Dismantled in 1930 after a series of minor revisions. Replaced in December 1929 and June 1930, respectively, by the 5-Foot Vertical Tunnel and the 7 x 10-Foot Atmospheric Wind Tunnel.

References: F. H. Norton, "National Advisory Committee's 5-Foot Wind Tunnel," Journal of the Society of Automotive Engineers (21 May 1921): 1-7; TR 195.

Purpose: To conduct aerodynamic investigations at high Reynolds numbers.

Initial cost: $262,000

Circuit and pressure: Continuous, annular return; 20 atmospheres

Test section: 5' diameter, closed throat

Drive system: Fan; 250-HP electric motor

Maximum speed: 51 MPH

Special features: 85-ton pressure shell with walls made from steel plate lapped and riveted according to a practice standard in steam-boiler construction. Built at Newport News (Va.) Shipbuilding and Dry Dock Co.

Key members of design team: Max M. Munk (proposed design); Frederick H. Norton, David L. Bacon, Smith J. DeFrance

Authorized: 4 March 1921

Operational: 19 October 1922

Major modifications: Converted to open throat in April 1928 after serious fire damage in August 1927. Because the new open throat did not work properly, returned to closed throat in December 1930.

Significance: "This tunnel represented the first bold step by the NACA to provide its research personnel with the novel, often complicated, and usually expensive equipment necessary to press forward the frontiers of aeronautical science." Jerome C. Hunsaker, Forty Years of Aeronautical Research. Smithsonian Institution Publ. No. 4247 (Washington, 1956), p. 256.

Disposition: Used from the early 1940s as a high-pressure air storage tank. Thoroughly inspected in 1954. Closed for recertification in 1981. In 1983 the LaRC Pressure Systems Committee recommended that the vessel no longer be used due to its age and riveted construction.

References: TRs 185, 277, 391, 416; TN 6

Purpose: To make possible accurate full-scale tests on aircraft propellers, fuselages, landing gear, tail surfaces, and other aircraft parts, as well as on model wings of large size.

Initial cost: $291,000

Circuit and pressure: Double return, atmospheric

Test section: 20' diameter, open throat

Drive system: Fan; two 1000-HP diesel engines (from naval submarine)

Maximum speed: 110 MPH

Special features: 8-bladed fan, 27' long

Key members of design team: Max M. Munk (proposed design); Fred E. Weick, Elton W. Miller, Donald H. Wood

Authorized: April 1925

Operational: July 1927

Major modifications: Changed to electric drive in 1933.

Significance: "The demonstrated inadequacies of theory, plus the failure to obtain a consistent correlation between model and full-scale results, made it clear that propeller data must ultimately come from tests at full scale. It was equally clear [that] full-scale testing in flight was slow and expensive. The only alternative was to build a wind tunnel large enough to take a full-sized propeller." Walter G. Vincenti, "The Air-Propeller Tests of W. F. Durand and E. P. Lesley: A Case Study in Technological Methodology," Technology arid Culture 20 (1979): 739.

Disposition: Torn down in 1950 to make way for the 8-Foot Transonic Pressure Tunnel. Reference: TR 300

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Purpose: To begin the investigation of dynamic phenomena occurring as the flow of air approached Mach 1 over small models.

Initial cost: Under $10,000

Circuit and pressure: Nonreturn, atmospheric

Test section: 11" diameter, closed throat

Drive system: Induction: compressed air from Variable-Density Tunnel injected at annular port immediately downstream from test section.

Maximum speed: Mach 1 (with no model in throat)

Key members of design team: Eastman N. Jacobs (open-throat design, 1928); John Stack and W. F. Lindsey (closed-throat design, 1932)

Authorized: ca. 1927

Operational: Open throat, 1928; closed throat, 1932

Major modifications: Closed-throat test section, 1932

Significance: "The injection scheme permitted runs of only about one minute before the pressure plummeted to useless values. These short runs, however, were sufficient to demonstrate the sharp rise in drag, the loss of lift, and the changes in pitching moments that occur near Mach 1." Baals and Corliss, Wind Tunnels of NASA, pp. 23 24.

Disposition: Replaced by 4 x 18-Inch High-Speed Tunnel in August 1940 and by 4 x 19-Inch High-Speed Tunnel in August 1949.

Reference: TR, 463

Purpose: To investigate the spinning characteristics of aircraft.

Initial cost: $8000

Circuit and pressure: Single-return, atmospheric

Test section: 5' diameter, open throat

Drive system: Fan; 50-HP electric motor

Maximum speed: 80 MPH

Special features: A vertical-axis balance

Key member of design team: Charles H. Zimmerman

Authorized: ca. 1928

Operational: December 1929

Major modifications: Changed to 4 x 6-foot, closed throat in 1938.

Significance: "By creating conditions that caused models to spin in the tunnel, spinrecovery procedures could be worked out on the ground without danger to pilots and planes." Baals and Corliss, Wind Tunnels of NASA, p. 19.

Disposition: Deactivated

References: TR 387, TN 734 Facilities

Purpose: To study general aerodynamic effects with particular reference to stability and control problems and the improvement of the lifting power of wings.

Initial cost: $64,000

Circuit and pressure: Single-return, atmospheric

Test section: 7' x 10', closed throat

Drive system: Fan; 200-HP electric motor

Maximum speed: 80 MPH

Special features: Six-component, floating-frame balance that could measure forces and moments exerted along and about spatial axes of the tunnel airstream.

Authorized: 1928

Operational: 8 July 1930

Significance: "[This tunnel] was a simple, plain workhorse. [It] went on, for some 15 years, to handle an ever increasing workload of essential low-speed testing including noteworthy systematic studies of stability, control, and high-lift devices. The 7-by-10 proportions were known from theory to minimize certain tunnel-wall correction factors .... The flat 10-foot wide 'floor' and the 7-foot high 'ceiling' allowed researchers and technicians easy access for model adjustments. [These dimensions] were retained in the early 1940s when four new atmospheric tunnels having increased speeds were procured for Ames and Langley." John V. Becker to author.

Disposition: Deactivated ca. 1946.

References: TRs 412, 664

Purpose: To make possible wind tunnel research into areas that could be explored best with full-scale models or with actual aircraft.

Initial cost: $900,000

Circuit and pressure: Double-return, atmospheric

Test section: 30' x 60', open throat

Drive system: Two fans; two 4000-HP electric motors

Maximum speed: 118 MPH

Key members of design team: Smith J. DeFrance, Abraham Silverstein, Clinton H. Dearborn

Authorized: February 1929

Operational: 27 May 1931 (formally dedicated during the 6th Annual Aircraft Engineering Conference)

Major modifications: Equipped for free-flight dynamic model studies in 1960s. Underwent major rehabilitation in 1977.

Significance: "The FST is perhaps the best example of a major NACA facility that found a multitude of additional uses not visualized in the beginning. In 1962, for example, it had an extended study of the handling problems of hypersonic aircraft and space reentry vehicles like the shuttle, using large free-flying models." John V. Becker to author.

Disposition: Operational

Reference: TR 459

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Purpose: To study the hydrodynamic resistance and other performance features of water-based aircraft.

Initial cost: $649,000

Dimensions: 2060' x 28' (avg. width) x 26' (avg. height)

Special features: Wave suppressors

Key member of design team: Starr Truscott

Authorized: March 1929

Operational: 27 May 1931

Major modifications: New higher-speed (80-MPH) carriage installed, 1936-1937. Tank extended by 900 feet to 2960 feet in 1936.

Significance: "The original research program at Langley made no provision for airplane hydrodynamics, and during its first decade the efforts of the staff were concentrated almost entirely on problems of the landplane. Many of the studies in wind tunnels were applicable to seaplanes, and they in common with landplanes benefited from improvements in wings, propellers, engine cowlings, and other developments of the 1920s. But it was recognized that the airplane on the water has problems that are not shared by the airplane in the air or on the landing strip, and in 1929 the Committee in Washington decided to enlarge the organization and equipment at Langley to provide for research in hydrodynamics." George W. Gray, Frontiers of Flight (New York, 1948), p. 65.

Disposition: Turned over to U.S. Navy in 1959.

References: TR 470, TN 513, TM 918

Purpose: To study methods (like supercharging) by which to increase the power and efficiency of aircraft engines and to improve ignition, cooling, and fuel economy.

Initial cost: $352,000

Description: Building with three dynamometer rooms, two fuel-spray research rooms, and a two-stroke-cycle test bed.

Key members of design team: Carlton Kemper, Addison Rothrock, Oscar W. Schey

Authorized: August 1933

Operational: September 1934

Significance: "The small but expert power plant staff made some important contributions, in addition to their cooperation with the wind-tunnel people in developing the remarkable NACA cowling for air-cooled engines. One recalls improved finning for air-cooled engine cylinders, methods to decrease the octane requirements of high-compression engines, and work on such fundamental matters as the behavior of fuels -how they ignite, how they burn, and how this burning corrodes critical parts of the engine." Jerome C. Hunsaker, Forty Years of Aeronautical Research, p. 264.

Disposition: Converted to office space after engine research moved to AERL in Cleveland in 1942.

References: TN 634; TRs 634, 644

Purpose: To investigate phenomena occurring as air near Mach 1 flowed over airfoils and fuselages at twice the Reynolds numbers of the 11-Inch HST.

Initial cost: $12,600

Circuit and pressure: Nonreturn, atmospheric

Test section: 24" diameter, closed throat

Drive system: Blowdown of compressed air from the VDT through annular injection nozzle Maximum speed: Mach 1 (with no model in throat)

Special features: Langley's first schlieren photographic system to show compressibility burbles and shock waves in air at high speeds; an improved manometer.

Key members of design team: Eastman N. Jacobs, John Stack, Ira H. Abbott, W. F. Lindsey, Kenneth Ward

Authorized: Ca. 1933

Operational: 3 October 1934

Major modification: Enclosure in August 1949 to reduce problem of water-vapor condensation.

Significance: "The complex phenomena of the compressibility burble were seen for the first time with the new schlieren system and correlated with the pressure distributions for various wing sections. This new understanding led quickly to the development of improved high-speed airfoils." John V. Becker to author.

Disposition: Replaced by 20-Inch Transonic Tunnel in 1953.

References: TR 646, ACR L4LO7A

Purpose: To conduct research on the general problems of spinning and stability and to test models of aircraft for which the spinning and stability characteristics were either unknown or known to be unsatisfactory.

Initial cost: $64,000

Circuit and pressure: Vertical nonreturn, atmospheric

Test section: 15' diameter, open throat; 12-sided polygon, closed throat

Drive system: Fan; 150-HP electric motor

Maximum speed: 40 MPH, variable to rate of falling aircraft model

Special features: Clockwork contained within the model automatically set the controls for recovery from a spin. Motion picture camera recorded the effects.

Key member of design team: Charles H. Zimmerman

Authorized: 8 June 1933

Operational: 3 April 1935

Significance: "During World War II, every fighter, light bomber, attack plane, and trainer over 300 designs-had to be tested in Langley's spin tunnels. Subsequently, over half of these aircraft were modified in some way to ensure that their controls would be able to pull them out of a spin." Baals and Corliss, Wind Tunnels of NASA, p. 42.

References: TR 557; Aero Digest (June 1935): 20-22.

Purpose: To test complete models of aircraft and aircraft components in a high-speed airstream approaching the speed of sound. Visualized as a full-speed companion to the low-speed Full-Scale Tunnel.

Initial cost: $266,000

Circuit and pressure: Single-return, atmospheric

Test section: 8' diameter, closed throat

Drive system: Fan; 8000-HP electric motor

Maximum speed: 575 MPH (Mach 0.75)

Special features: Because of the Bernoulli effect, the test chamber had to withstand powerful, inwardly directed pressure. An igloo structure with concrete walls a foot thick housed the test section. Operating personnel located inside the igloo were subjected to pressures equivalent to 10,000-foot altitude and had to wear oxygen masks arid enter through airlocks. A heat exchanger removed the large quantities of heat generated by the big fan.

Key members of design team; Russell G. Robinson and Manley J. Hood; idea for tunnel first suggested by Eastman N. Jacobs.

Authorized: 17 July 1933; approval of funds by Federal Administrator of the Public Works Administration, under the authority of the National Industrial Recovery Act of 16 June 1933.

Operational: 28 March 1936

Major modifications: Repowered to 16,000 HP (Mach 1 capability), Feb. 1945. Mach 1.2 contoured nozzle installed, Dec. 1947. Slotted-throat test section installed, 1950.

Significance: "Perhaps the most important contribution of this trailblazing tunnel came from its investigations of complete aircraft models (made possible for the first time by its large size) in which the causes and cures for the severe adverse stability and control problems encountered in high-speed dives were first delineated. This tunnel also produced the high-speed cowling shapes used in World War II aircraft, and the new family of efficient air inlets used in jet aircraft. The first 500-MPH investigations of propellers were made here early in the war. After repowering, with new support systems, the 8-Foot Tunnel produced precise transonic data up to Mach numbers as high as 0.92 for such aircraft as the X-1, D-558, and others. Its final achievement was the development and use in routine operations of the first transonic slotted throat. The investigations of wing-body shapes in this tunnel led to Whitcomb's discovery of the transonic area rule. Surely, this is one of the most impressive records in the NACA or anywhere else of what can be accomplished in the hands of imaginative, competent researchers." John V. Becker to author, 18 Oct. 1984.

Disposition: Deactivated in 1956.

Reference: AR 1936

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Purpose: To study spinning and stability characteristics in free flight without the expense of building, testing, and modifying full-scale aircraft.

Initial cost: $120,000

Circuit and pressure: Nonreturn, atmospheric

Test section: 5' diameter

Drive system: Fan; 5-HP electric motor

Maximum speed: 25 feet per second

Special features: With one hand an engineer adjusted the speed of the tunnel and with the other hand he tilted the tunnel up, down, or around to follow the motion of the model. The basic idea was to get the model to remain stationary and horizontal in the rising airstream of the tilted tunnel, constantly adjusted to match the aircraft's glide angle. The engineer piloted the model's control surfaces via electrical signals sent through thin wires trailing behind the model.

Authorized: 1936

Operational: 20 April 1937

[457] Significance: "Wind tunnel research has developed problems which required entirely new instrumental applications. One such problem originating at Langley came from the group which [operated] the free-flight tunnel. In this tunnel, instead of installing the airplane model on balances, the engineers actually fly it in the windstream while records are made of the effectiveness of the controls .... In early studies with [this tunnel] the model all too often would swerve to one side and crash into the tunnel wall. The Instrument Research Division was asked to correct this erratic performance....and shortly produced an automatic control device which responded to a light placed at the end of the tunnel. By this means the model is caused to seek the light, and through its use the smash-ups have been reduced to a low figure." George W. Gray, Frontiers of Flight, pp. 55-56.

Disposition: Replaced by 12-Foot Free-Flight Tunnel in 1939.

Purpose: Ostensibly (that is, as stated for funding purposes) to study ice formation on airplane models and parts, but actually to assess the performance of airfoils in an airstream of very low turbulence level, approaching that of the smooth air of free flight.

Initial cost: $103,000

Circuit and pressure: Single-return, 1-10 atmospheres

Test section: 3' x 7.5', closed throat. Contraction ratio 19.6 to 1. Screening to reduce turbulence.

Drive system: Fan; 200-HP electric motor

Maximum speed: 155 MPH

Special features: To fulfill the announced purpose, icing research, Langley insulated the walls of this tunnel with a thick wrapping of crude insulation ( kapok from life preservers) and added makeshift refrigeration equipment (consisting of an open tank of ethylene glycol cooled by blocks of ice). A pump circulated the cold mixture through coils that cooled air drawn from the tunnel.

Key members of design team: Eastman N. Jacobs and Ira H. Abbott

Authorized: 28 May 1937

Operational: 15 June 1938

Major modifications: After the completion of a perfunctory series of icing tests, the refrigeration equipment was removed and an array of honeycombs and screens was installed upstream of the test section to homogenize the airflow. Testing of the low-drag potential of various airfoils then began.

Significance: "[This tunnel] was built as an experimental model to try out the idea of radical contraction and screening, to see if the combination would really lower the turbulence. It did, and the researchers began to plan a larger and still more radical tunnel [the Low-Turbulence Pressure Tunnel]." George W. Gray, Frontiers of Flight, p. 48.

Disposition: Dismantled, 1947-1948

Reference: TN 1283

Purpose: To study spinning and stability characteristics of aircraft models in free flight, improve airplane safety, and test radically new aircraft design types.

Initial cost: approx. $250,000

Circuit and pressure: Annular return, atmospheric

Test section: 12' diameter, 12-sided/8-sided polygon

Drive system: Fan; 600-HP electric motor (5-minute rating)

Maximum speed: 50 MPH

Special features: As the model rose from the tunnel floor, climbed, dived, and banked, a camera recorded a motion picture of its responses to remote controls.

Key member of design team: Charles H. Zimmerman

Authorized: 1937

Operational: 1939

Significance: "[This tunnel was] useful with radically new aircraft where no reservoir of flight experience was available, namely, tailless aircraft, planes with delta and skewed wings, and vertical takeoff and landing/short takeoff and landing (VTOL/STOL) vehicles." Baals and Corliss, Wind Tunnels of NASA, p. 28.

Disposition: Used into the early 1950s; supplanted by powered models flown in the Full Scale Tunnel.

Reference: TN 810

Purpose: The high Reynolds number study of propellers and three-dimensional wings, as well as the stability and control characteristics of models of complete aircraft. Built in response to continued concern over the problem of scale effects.

Initial cost: $1,100,000

Circuit and pressure: Single-return, 2.7 atmospheres (0-40 psia)

Test section: 19', closed throat

Drive system: 34'6" fan; 8000-HP electric motor

Maximum speed: 330 MPH

Special features: Researchers had to enter their working quarters through a decompression chamber.

Key members of design team: Smith J. DeFrance, John F. Parsons, Arthur A. Regier, James G. McHugh, John C. Messick

Authorized: 22 June 1936

Operational: 20 June 1939

Major modifications: Converted to Transonic Dynamics Tunnel, 1955-1959, to study aeroelasticity, flutter, buffeting, vortex shedding, gust loads, and other dynamic characteristics. The TDT incorporated a slotted test section, new mounts, a quickstop drive system, a gust-maker or airflow oscillator, and a Freon-12 test medium system.

Significance: "[The 19-Foot Pressure Tunnel[ was the first attempt anywhere to combine large size and high pressure in a single facility." Bath and Corliss, Wind Tunnels of NASA, p. 29. "This tunnel was originally visualized as a 'super PRT,' but it became apparent before it was finished that its speed was too low for high-speed propeller research; this part of its intended usage was transferred to the new Langley 16-Foot High-Speed (500-MPH) Tunnel. The 19-Foot Pressure Tunnel conducted a great.....

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[462]....deal of useful testing of complete aircraft models at higher Reynolds numbers than other low-speed Langley tunnels, but did not produce any landmark results like the original PRT." John V. Becker to author.

Disposition: Operational as Transonic Dynamics Tunnel.

Reference: NASA TN D-1616, March 1963.

Purpose: To provide an experimental capability for investigating the problems encountered in the design of advanced aircraft structures.

Initial cost: $803,000

Special equipment: NACA Combined Loading (six components) Testing Machine; many tension and compression testing machines; optical and electrical strain measuring equipment; large, strong testing floor and vertical backstop; carbon-rod and quartztube radiators for simulating aerodynamic heating.

Key members of design team: Joseph N. Kotanchik and Norris F. Dow Authorized: 23 August 1939 Operational: 18 October 1940

Major modifications: Addition of power supply and control system for radiant heating of structures, 1958.

Significance: "This general-purpose structures research laboratory was designed to be adaptable to a variety of testing requirements. Initial experimental and theoretical research concentrated on he strength of structures in compression and the stress distribution in redundant structures. Fatigue testing began in 1943, long before metal fatigue became a major factor in airplane design. A major transition in research began about 1950 to the structural problems of supersonic aircraft and missiles. This laboratory led the development of radiant heating devices used worldwide for the laboratory simulation of arodynamic heating of structures. Support of ballistic missile programs led to the early development and research use of electric-arcpowered jets for testing thermal protection materials for reentry vehicles." Richard R. Heldenfels to author.

Disposition: Operational

References: R. W. Peters, "The NACA Combined Loading Testing Machine," Proceedings

of the Society for Experimental Stress Analysis, 13, 1955; Richard R. Heldenfels, "High Temperature Testing of Aircraft Structures," NATO AGARD Report 205, Oct. 1958; NASA TM X-1129, July 1065.

Purpose: To investigate spinning characteristics of aircraft, especially those with high wing loading factors.

Initial cost: $100,000

Circuit and pressure: Vertical with annular return, atmospheric

Test section: 20' diameter 12-sided polygon, closed throat

Drive system: Fan; 400-HP electric motor (1300-HP overload)

Maximum speed: 66 MPH

Special features: Tiny electric servo-actuators drive the model's control surfaces, activated electromagnetically to initiate recovery from a spin.

Key member of design team: Oscar Seidman

Authorized: March 1939

Operational: 5 March 1941

Major modifications: Minor changes to accommodate study of capsules and recovery devices in vertical descent, late 1950s.

Significance: "Out of [investigations in this and Langley's other spin tunnels came[ three methods of modifying an airplane to make it controllable in a spin; first, enlarge the vertical tail by extending it back, thus providing more surface to act against the air; second, lift the horizontal tail and set it at a higher level on the body of the airplane; third, extend the fin forward on the underside of the tail, that is, put in a ventral fin." George W. Gray, Frontiers of Flight, p. 156.

Disposition: Operational

Reference: NACA L-86258

Purpose: To provide reliable airfoil data at high Reynolds numbers and, more specifically, to develop low-drag airfoil.

Initial cost: $611,000

Circuit and pressure: Single-return, 1-10 atmospheres (1-150 psia)

Test section: 7'6" x 3', closed throat

Drive system: Fan; 2000-HP electric motor

Maximum speed: 300 MPH (1 atm.), 220 MPH (4 atm.), 160 MPH (10 atm.)

Special features: Eleven screening elements to reduce turbulence levels; high-contraction ratio entrance cone; unusual method of measuring lift and drag.

Key members of design team: Eastman N. Jacobs, Ira H. Abbott, Albert E. von Doenhoff Authorized: 1938

Operational: Spring 1941

Major modifications: Converted for use with Freon, 1947-1948; converted to slotted throat in 1953. (Neither of these modifications was very successful, however.)

Significance: "When the LTPT commenced operation in the spring of 1941, it began war work on a crash basis. With its unique low-turbulence-flow characteristics, it was an ideal tool with which to explore the capabilities of a revolutionary type of wing-the newly conceived laminar-flow airfoil." Baals and Corliss, Wind Tunnels of NASA, p. 40.

Disposition: Served on a standby basis as a pressure vessel for the 26-Inch Transonic Blowdown Tunnel after 1055; reactivated in early 1970s because of interest in lowspeed characteristics of new types of supercritical airfoil.

Reference: TN 1283

Purpose: To investigate various aerodynamic problems of airplanes, including cowling and cooling of full-size engines and propellers, at high speeds.

Initial cost: $1,422,000

Circuit and pressure: Single-return, atmospheric

Test section: 16' diameter, closed throat

Drive system: Fan; 16,000-HP electric motor

Maximum speed: Mach 0.7

Special features: 2000-HP and 0000-HP dynamometers for full-scale propeller testing

Key members of design team: ])avid J. Biermann and Lindsey I. Turner, Jr.

Authorized: 1939

Operational: 5 December 1941

Major modifications: Changed to 14-foot slotted-throat test section with octagonal throat and repowered to 60,000-IP drive, 1950; 35,000-HP plenum suction blower, 1969.

Significance: "Tests of full-scale aircraft nacelles with operating engines and propellers during the first two year of operation encountered many difficulties: choking of the tunnel at Mach numbers of about 0.6, with the associated distortions in the flow; inadequate angle-of-attack ranges, etc. This type of testing was terminated in 1943. But this tunnel proved ideal for investigating full-scale propellers with the high-powered electric dynamometers at airspeeds up to low supersonic speeds. With its relatively large-size test models it has been possible in more recent years to....

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	.	The 16-Foot High-Speed Tunnel at the time of its dedication in 1941. Left, a scale model of a jet airplane being tested in the tunnel during the 1950s.

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[466] ....simulate effectively jet engine exhaust on aircraft models using hydrogen peroxide or compressed air." John V. Becker to author.

Disposition: Operational as 16-foot Transonic Tunnel.

Reference: RM L52E01, July 1952.

Purpose: To study the individual aerodynamic components of rotational motion in flight.

Initial cost: $295,000

Circuit and pressure: Single-return, atmospheric

Test section: Dual (interchangeable): 75" diameter or 6' x 6'; closed throats

Drive system: Fan; 600-HP electric motor

Maximum speed: 250 MPH

Special features: Rotating paddles started air swirling in test section; sides of 6 x 6-foot section were adjustable to different radii of curvature so that models could be tested in curved flow.

Operational: June 1942

Significance: "For many year the stability tunnel provided data for predicting the maneuvering performance of aircraft and missiles. Its eventual demise was hastened by the perfection of oscillating model techniques." Baals and Corliss, Wind Tunnels of NASA, p. 44.

Disposition: Deactivated and transferred to Virginia Polytechnic Institute in 1958 for use as an educational tool.

Reference: TN 2483

Purpose: To test models of floats for seaplanes and hulls for flying boats by dragging them through seawater.

Initial cost: $429,000

Description: Basin 1800' long, 8' wide, 6' deep; 60-MPH carriage

Design team: Starr Truscott, John B. Parkinson, John R. Dawson

Authorized: 2 May 1939

Operational: 18 December 1942

Significance: "[In this tank, researchers] experimented with radical departures from accepted hull design, trying o find the specifications for a seaplane body that would combine freedom from porpoising and skipping, low water resistance, and superior performance in the air. Out of these experiments [came] a novel design known as the hull with a planning tail." George W. Gray, Frontiers of Flight, p. 80.

Disposition: Deactivated in 1960s; carriage used in wake-vortex studies in 1970s.

References: TR 753; WRs L-5M, L-687

Purpose: To measure impact loads on seaplane hulls.

Initial cost: $311,000

Description: Basin 360' long, 26'8" wide, 8' deep; made waves up to 3'.

Authorized: 2 May 1939

[467] Operational: 10 November 1942

Significance: This facility led to the development of various aircraft ditching aids, such as hydroflaps and hydrofoils.

Disposition: Building used from 1950s as LaRC photographic laboratory.

Reference: TR 795

Purpose: To explore supersonic flight problems and fundamental supersonic flow phenomena.

Initial cost: Indeterminate, but probably less than $100,000.

Circuit and pressure: Atmospheric intake, nonreturn; stream pressures from 1/5 to 1/3 atmosphere

Test section: 9" x 9"

Drive system: Axial-flow compressor; 'variable-speed 1000-HP electric motor

Maximum speed: Mach 2.5

Key members of design team: Eastman N. Jacobs, Macon C. Ellis, Clinton E. Brown, Arthur Kantrowitz

Authorized: 1939

Operational: July 1942

Major modifications: Changed to closed-circuit dry air operation in mid-1940s; repowered to 3500-HP drive ca. 1946.

Significance: "This pioneering little supersonic tunnel provided timely education and experience for the NACA in the 941-1945 period immediately preceding the major drive for large supersonic tunnels." John V. Becker to author.

Disposition: Dismantled

Purpose: To reduce the backlog of work in Langley's 7 x 10-Foot Atmospheric Wind Tunnel (operational 1930) caused by World War II.

Circuit and pressure: Single-return, atmospheric

Test section: 7' x 10', closed throat

Drive system: Fan; 1600-HP electric motor

Maximum speed: 300 MPH

Special features: Remote-control survey apparatus permitting rapid exploration of airflow behind models; six-component balance system.

Key members of design team: Thomas A. Harris and Charles J. Donlan

Authorized: 1942

Operational: February 1945

Major modifications: 17' x 17' test section installed in settling chamber upstream of original test section, 1956.

Significance: The modified tunnel provided conditions appropriate for testing of aircraft in transition from hovering to cruising flight.

Disposition: Dismantled 1970

Purpose: To investigate aircraft loads produced by atmospheric turbulence and other unsteady flow phenomena and to develop gust alleviation devices.

Initial cost: Indeterminate

Circuit and pressure: Reversible single-return, atmospheric

Test section: 8' x 14', open throat, adjustable angle (jet type)

Drive system: 75-HP electric motor

Maximum speed: 100 MPH

Special features: Apparatus consisted of a catapult for launching dynamically scaled models into steady flight, a jet of air for simulating a gust, curtains for catching the model after it traversed the gust, and instruments for recording the model's responses.

Key members of design team: Philip Donely and Mike Goldberg

Authorized: June 1943

Operational: August 1945

Significance: "Often the gust revealed values that were not found by the best known

methods of calculation. In one instance, for example, the gust tunnel tests showed " that it would be safe to deign the airplane for load increments 17 to 22 percent less than the previously accepted values." George W. Gray, Frontiers of Flight, p. 174. "The gust tunnel was on of a breed of facilities (like the spin tunnel, free-flight tunnel, and impact basin) that provided information to verify basic theories and concepts. The gust tunnel became obsolescent because its Reynolds number and Mach number capabilities were low." Philip Donely to author.

Disposition: Dismantled in 1965 after being used as a low-velocity instrument laboratory and noise research facility.

Purpose: To study the serious and poorly understood problem of aeroelasticity and the effects of flutter on aircraft.

Circuit and pressure: Single-return, 0 o 1.8 atmospheres (air or Freon-12 as test medium)

Test section: 4'6" diameter, closed throat. Dual (interchangeable): four-component hydraulic balance section; flutter test section with 17 viewing portals.

Drive system: 1000-HP electric motor

Maximum speed: Mach 1

Authorized: 1944

Operational: September 1945

Significance: "Transonic aerodynamics further complicated an already complex aeroelastic problem . ... Aircraft designers needed definitive wind-tunnel tests to assure them that their thin-winged aircraft would not experience flutter under any anticipated flight conditions." Baals and Corliss, Wind Tunnels of NASA, p. 79

Disposition: Operational

Purpose: To investigate general aerodynamic effects at high speed, especially stability and control problems into and through the critical speed range.

Initial cost: $2,052,000

Circuit and pressure: Single-return, atmospheric

Test section: 7' x 10', closed throat, adjustable

Drive system: Fan; 14,000-HP electric motor

Maximum speed: 675 MPH (approx. Mach 0.9)

Key members of design team: Thomas A. Harris and Charles J. Donlan

Authorized: 1943

Operational: November 1945

Major modifications: Tansonic bump installed, ca. 1946; slotted test section, ca. 1953, increased maximum speed to Mach 1; connected to 35,000-HP compressor of 16-Foot HST in mid-1950s, increasing speed to Mach 1.2.

Significance: "Whereas the test area of the 300-MPH tunnel was expanded for low-speed work, the test section of it high-speed twin was constricted by a carefully designed 'bump.' Air flowing over the bump was accelerated to the transonic range even though the main airflow remained subsonic. This modification, though crude, led to a qualitative exploration of the transonic range that was just opening up after [World War II]." Baals and Corliss, Wind Tunnels of NASA, p. 37.

Disposition: Operational under direction of Full-Scale Research Division, but no longer has Mach 1 capability.

References: TN 3469, NASA TMX-1130

Purpose: To conduct research n the aerodynamics of subsonic and supersonic internal flows, such as the optimum methods of inducing air and supplying it to conventional and jet engines.

Special equipment: Air supply provided initially by three 1000-HP blowers.

Key members of design team: Kennedy F. Rubert and 3. R. Henry

Authorized: 1944

Operational: March 1946

Major modifications: Underwent major upgrading in 1950s involving use of the replaced 16,000-HP motors from the repowered 16-Foot HST to drive larger blowers.

[471] Significance: "Like the original concept of the NACA Lewis Flight Propulsion Laboratory in Cleveland, this small laboratory was originally aimed at piston engine problems and had to be reoriented towards jet engines and ramjet combustion research. Eventually it was connected to the central air supply of the Gas Dynamics Laboratory at Langley and applied to hypersonic ramjet research." John V. Becker to author.

Disposition: Operational under NASA, in part as a high-intensity noise research facility. Test cells now devoted to hypersonic ramjet propulsion research under High-Speed Aerodynamics Division.

Purpose: To investigate fundamental factors affecting the performance, stability and control, and vibration characteristics of helicopters.

Description: Worked on the old principle of the whirling arm. Apparatus consisted of a cone-shaped steel tower 40 feet high with a drive shaft in its center for mounting a helicopter rotor. Strain gauge measured the torque and thrust on the shaft. Cameras recorded action of whirling rotor.

Key member of design team: Frederic B. Gustafson

Authorized: 1944

Operational: March 1946

Disposition: Deactivated in 1960s, but reactivated ca. 1970. Dismantled 1976 when NASA shifted helicopter work to Ames Research Center.

Purpose: To explore the potential of flight at high Mach numbers. Inspired by Allies' discoveries concerning Nazi Germany's V-2 ballistic missile program at Peenemunde. Served as pilot model for large Continuous-Flow Hypersonic Tunnel.

Initial cost: approx. $200,000

Circuit and pressure: Nonreturn, 36 atmospheres (540 psia)

Test section: 11" x 11"

Drive system: Blowdown. To reach high pressure ratios, air from a 50-atmosphere pressure tank was blown through the test section into an evacuated tank. With high pressure on one side and very low pressure on the other, generated pressure ratios could be maintained for about 100 seconds.

Maximum speed: Mach 7

Special features: Electric resistance heater raised temperatures in settling chamber to 900°F.

Key members of design team: John V. Becker and Charles H. McLellan

Authorized: 1945

Operational: 1947

Significance: "Small pilot tunnels of the NACA were often used for other purposes, but the 11-Inch Hypersonic Tunnel went far beyond this to become a star in its own right....Our experience with this remarkable tunnel and other 'blowdown' or 'intermittent' hypersonic tunnels suggested clearly that they are preferable to the continuous-flow type which is extremely costly in drive compressor equipment. Long runs are not essential with modern instrumentation." John V. Becker to author.

Disposition: Operational under direction of Aero-Physics Division until 1973 when it was dismantled. Later given to Virginia Polytechnic Institute.

[472] Reference: John V. Becker, "Results of Recent Hypersonic and Unsteady Flow Research at the Langley Aeronautical Laboratory," Journal of Applied Physics 21 (July 1950): 619-628.

Purpose: To investigate supersonic aerodynamics problems on models large enough to permit installation of extensive instrumentation, and to provide detailed information on viscous and interference effects unobtainable in smaller supersonic tunnels.

Initial cost: $909,000

Circuit and pressure: Single-return, 1/4 atmosphere

Test section: 4'6" x 4'6"

Drive system: 6000-HP electric motor driving a seven-stage axial compressor capable of handling 860,000 cubic keep of air per minute at a compression ratio of 2. The compressor was the key to he whole design.

Maximum speed: Mach 2.2

Special features: Flexible walls in test section; adjustable contour nozzle; drying and cooling equipment to reduce moisture content of tunnel air.

Key members of design team: Donald D. Baals and Kent Horton. The compressor was designed by M. F. Miller and J. R. Runckel of the 16-Foot HST staff.

Authorized: 1945

Operational: 1948 (construction halted for nearly two years by strike of the industrial contractor assigned the mechanical design and actual fabrication)

Major modifications: Repowered in 1950 to 45,000 HP (continuous) and 60,000 HP (for 30 minutes).

Significance: "Finally on the line, the 4 x 4-foot supersonic tunnel made up for lost time. Many well-known military aircraft and space vehicles were tested through the years: the famous Century Series fighters (F-102, F-105, etc.), the B-58 supersonic bomber, the X-2 research aircraft, and so on." Baals and Corliss, Wind Tunnels of NASA, p. 51.

Disposition: Dismantled in 1977, but drive motors, cooling tower, and some support facilities incorporated into new National Transonic Facility (built on the same site and operational in 1983).

Reference: NASA TM X-1130

Purpose: To study aerodynamic effects in the troublesome transonic speed range and to investigate flutter characteristics.

Initial cost: $135,000

Circuit and pressure: Nonreturn, 7 atmospheres

Test section: 26" octagonal, slotted top and bottom walls

Drive system: Induction; compressed air from LTPT (150 psia)

Maximum speed: Mach 1.45

Key members of design team: Albert E. von Doenhoff, and Laurence K. Loftin, Jr.

Authorized: ca. 1948

Operational: 1950

Significance: "The validity of flutter data obtained in the 26" TBT was substantiated in 1951 by comparative tests. Studies were made in this tunnel with models, appropriately scaled, similar to those for which flutter data had been obtained beyond Mach 1 by the free-fail drop-model technique. Agreement between results obtained from the two different test techniques was gratifyingly close. Following these comparative investigations, systematic studies of the effect of such wing planform variables as aspect ratio and sweepback angle on flutter in the Mach number range between 0.8 and .4 were undertaken in the TBT. The results of these studies began to appear in 1953. Shortly thereafter, the TBT was in great demand for investigations of the gutter characteristics of various aircraft and missile configurations." Laurence K. Loftin, Jr., "Notes on Flutter Investigation of Republic F-105 Tail Surfaces in the NACA 26-Inch Transonic Blowdown Tunnel," 12 January 1983, copy in LaRC Historical Archives.

Disposition: Deactivated in 1970s.

Purpose: To research basic aerodynamic, heating, and fluid mechanical problems in the speed ranges upwards from the conventional supersonic tunnels to hypersonic and space-reentry conditions.

Initial cost: $5.5 million

[474] Circuit and pressure: Nonreturn, 200 atmospheres

Test section: Typically 20"

Drive system: induction. Central 3000-psi tank farm provided heated air to several small cells.

Maximum speed: Mach 8

Special features: Huge steam and electric resistance heaters warm air to 680° and 1040°F, respectively, and prevent liquefaction in the test cells.

Key members of design team: Antonio Ferri, Macon C. Ellis, Clinton E. Brown

Authorized: ca. 1949

Operational: 1951

Major modifications: Under NASA, when models of various spacecraft had to be tested at reentry Mach numbers, pure nitrogen and helium were used as test medium instead of heated air.

Disposition: Operational

Purpose: To further the study o transonic aerodynamics at high Reynolds numbers, and in particular to investigate flutter and buffeting in the transonic regime.

Initial cost: $5,495,000

Circuit and pressure: Single-return, 0.1 to 2.0 atmospheres

Test section: 7'1" x 7'1", slotted throat

Drive system: Fan; 25,000-HP electric motor

Maximum speed: Mach 1.2

Special features: Fine grid water-cooled coil in airstream removed excess heat but added no moisture to the circulating air.

Key members of design team: John Stack, Eugene C. Draley, Ray H. Wright, Axel T. Mattson

Authorized: Ca. 1951

Operational: 1953

Major modifications: Plenum suction added, 1958, increasing speed to Mach 1.3.

Significance: Langley engineers designed this tunnel from its inception using the new concept of the slotted wall.

Disposition: Operational

Purpose: To contribute force, moment, pressure-distribution, and heat-transfer studies of high-speed airflow.

Initial cost: $15,427,000

Circuit and pressure: Single-return, 150 psia. (Normal operating temperature approx. 150°F with heat bursts of 300-400°F for heat-transfer studies.)

Test section: Dual. Both 4' x 4; one capable of Mach 1.5 to 2.9 and the other capable of Mach 2.3 to 4.6.

Drive system: Family of electric motors rated at 100,000 HP, plus four compressor units Maximum speed: Mach 4.6

Special features: Asymmetric supersonic nozzle developed at Ames Research Center

Key member of design team: Herbert A. Wilson Authorized: 27 October 1949 (Unitary Plan Act)

Operational: 1955

Significance: "A long series of missiles passed through the 4 x 4-Foot Unitary Tunnel, where they were tested for high-speed performance, stability and control, maneuverability, jet-exhaust effects, and Other performance factors .... Despite the original dedication of this tunnel to missile development, it had been in operation scarcely a year before the now-famous McDonnell F-4 Phantom was being tested in model form. Later, the X- 15, the F-111, and various supersonic transport configurations, as well as models of space vehicles, could be found mounted in the test section." Baals and Corliss, Wind Tunnels of NASA, pp. 68-69.

Disposition: Operational

Reference: Manual for Users for the Unitary Plan Wind Tunnel Facilities of the NACA, 1956.

Purpose: To provide a capability to test aircraft and missile structural components under the combined effects of aerodynamic heating and loading.

Initial cost: $3,723,000

Circuit and pressure: Nonreturn, 3.4 to 13.6 atmospheres (stagnation pressure to 200 psia), 300° to 660°F

Test section: 8'9" x 6', solid walls with numerous viewing ports

Drive system: Induction; 600-psia Or stored in a tank farm filled by a high-capacity compressor located in an adjacent facility; exhausted to the atmosphere.

Maximum speed: Mach 3

Special features: 9 x 6-Inch Model Tunnel (1960)

Key members of design team: Richard R. Heldenfels and E. Barton Geer

Authorized: FY 1953. (In response to recommendations of its advisory committees, NACA management had decided in 1951 that a large, high-temperature structures research laboratory should be constructed at Langley to conduct experiments on structures for supersonic aircraft and missiles. A heated test chamber equipped with loading devices was proposed in June 1951, but further study and some spectacular test results in 1952 revealed that a ground facility that more nearly duplicated the flight environment was needed.)

Operational: September 1957. (Construction was delayed by a federal budget reduction action and by studies required o solve a few design problems.)

Major modifications: Additional air storage, 1957; high-speed digital data system, 1959; subsonic diffuser, 1960; Topping compressor, 1961; boost heater system (2000°F hot core provided by propane burners in the settling chamber), 1963.

[478] Significance: "Research use of t ]is facility was primarily concerned with the effects of aerodynamic heating and loading in combination on the structural integrity of vehicle components with emphasis km panel flutter. The many specific components tested included the vertical tail of the X-15 research airplane, the heat shields of the Centaur launch vehicle and the Project Fire entry vehicle, and elements of the Hawk, Falcon, Nike, Sam-D, and Minuteman missiles. The high-intensity noise field (162 db) at the tunnel exit was used occasionally to test the response of humans, equipment, and structures that include the Project Mercury capsule." Richard R. Heldenfels to author.

Disposition: Deactivated on 30 September 1971 as a result of metal fatigue in the air storage field which caused an accident that destroyed part of the facility and damaged other property. The failure resulted from wind-induced oscillations of a manifold loop between bottles. In the mid-1970s, all tunnel equipment was removed and the buildings converted to other uses.

References: NASA TNs D-517, -907, D-921, D-1358; NASA TM X-1130

Purpose: To investigate heat transfer, pressure, and forces acting on inlets and complete models in the hypersonic regime.

Initial cost: $1,409,000

Circuit and pressure; Nonreturn, 220-550 psia; running time over 15 minutes Test section: 20" diameter

Drive system: Induction

Maximum speed: Mach 6

Special feature: Electrical resistance heater

Key members of design team: John V. Becker and Eugene S. Love

Authorized: 1957

Operational: 1958

Disposition: Operational under direction of High-Speed Aerodynamics Division.

Reference: NASA TN D-6280

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