During the 1990s two SR-71 Blackbird aircraft were used by NASA 

as testbeds for high-speed and 

high-altitude aeronautical research 

at Dryden. The aircraft included an 

SR-71A and SR-71B (the trainer version), loaned to NASA by the U.S. 

Air Force. 

The SR-71, the most advanced 

member of the Blackbird family that 

included the A-12 and YF-12, was 

designed by a team of Lockheed 

personnel led by Clarence “Kelly” 

Johnson, then vice president of 

Lockheed’s Advanced Development 

Company Projects, commonly known 

as the “Skunk Works” and now a part 

of Lockheed Martin Corp.

The Blackbird design originated in 

secrecy during the late l950s with 

the A-12 reconnaissance aircraft that 

first flew in April 1962 and remained 

classified until 1976. President Lyndon Johnson publicly announced the 

existence of the YF-12A interceptor 

variant on Feb. 29, 1964, more than 

half a year after its maiden flight. The 

SR-71 completed its first flight on 

SR-71 Blackbird

EC97 43933-4
 NASA Facts

Dec. 22, 1964. More than a decade after their 

retirement the Blackbirds remain the world’s 

fastest and highest-flying production aircraft 

ever built.

The Blackbirds were designed to cruise at 

Mach 3.2, just over three times the speed of 

sound or more than 2,200 miles per hour and 

at altitudes up to 85,000 feet. The extreme operating environment in which they flew made 

the aircraft excellent platforms for conducting 

research and experiments in a variety of disciplines: aerodynamics, propulsion, structures, 

thermal protection materials, high-speed and 

high-temperature instrumentation, atmospheric studies and sonic boom characterization.

SR-71 activities at Dryden were part of 

NASA’s overall high-speed aeronautical research program and involved other NASA 

research centers, other government agencies, 

universities and commercial firms. Data from 

the SR-71 research program will aid designers 

of future supersonic/hypersonic aircraft and 

propulsion systems.

Research at Mach 3

One of the first major experiments flown on 

the NASA SR-71 involved a laser air-data 

sensor. The sensor used laser light instead 

of air pressure to generate airspeed and attitude data such as angle of attack and sideslip, data normally obtained with small tubes 

and vanes extending into the airstream or 

from tubes with flush openings on an aircraft’s outer skin. These flights also provided 

information on the presence of atmospheric 

particles at altitudes above 80,000 feet, 

where future hypersonic aircraft will operate. The system used six sheets of laser light 

projected from the bottom of the airplane. 

As microscopic-size atmospheric particles 

passed between the two beams, direction 

and speed were measured and processed 

into standard speed and attitude references. 

An earlier laser air-data measurement system was successfully tested at Dryden on a 

modified F-104 testbed aircraft. 

The first of a series of flights using the SR-71 

as a science camera platform for NASA’s Jet 

Propulsion Laboratory, Pasadena, Calif., was 

flown in March 1993. From the nose bay of 

the aircraft, an upward-facing ultraviolet video 

camera recorded data on celestial objects in 

wavelengths blocked to ground-based astronomers by Earth’s atmosphere.

In another project, researchers at the University of California-Los Angeles used the SR71 to investigate the use of charged chlorine 

atoms to protect and rebuild the ozone layer.

As part of NASA’s commercialization assistance program, the SR-71 served as a 

testbed in development of a commercial 

satellite-based, instant wireless personal 

communications network called IRIDIUM. The 

IRIDIUM system was developed by Motorola’s 

Satellite Communications Division and during 

developmental testing, the SR-71 acted as a 

surrogate satellite for transmitters and receivers on the ground.

Because of its high-speed capabilities, scientists used the SR-71 in a program to study 

ways of reducing sonic boom overpressures 

that are heard on the ground much like sharp 

thunderclaps by aircraft exceeding the speed 

of sound. Aircraft designers have used data 

from the study in efforts to reduce the “peak” 

of sonic booms and minimize the “startle effect” they produce on the ground.

In 1997 and 1998 the SR-71 carried the 

Linear Aerospike SR-71 – or LASRE – experiment. The LASRE test apparatus was a 

half-span scale model of a lifting body with 

eight thrust cells of a linear aerospike engine, 

mounted on the back of an SR-71 aircraft 

during flight at high speeds and altitudes. 

Outfitted with the test fixture, the aircraft operated like a kind of flying wind tunnel that al-
 NASA Facts

lowed engineers to gather aerodynamic data 

under realistic flight conditions.

By the time the Air Force loaned the two SR71s to Dryden the center already had a decade of past experience with the Blackbirds. 

Three of the aircraft were flown at the facility 

between December 1969 and November 1979 

in a joint NASA/Air Force program aimed at 

learning more about the capabilities and limitations of high-speed, high-altitude flight. The 

first two were YF-12A prototypes of a planned 

interceptor aircraft based on the initial A-12 

design that ultimately evolved into the SR71 reconnaissance aircraft. While plans were 

under way to add another aircraft to the fleet, 

one YF-12A was lost in a non-fatal mishap in 

1971. The third aircraft, an SR-71A that was 

given the designation YF-12C for administrative purposes, soon took its place.

NASA researchers used the YF-12s for a wide 

variety of experiments involving aerodynamic 

and thermal loads, aerodynamic drag and 

skin friction, heat transfer, airframe and propulsion system interactions, inlet control system improvements, high-altitude turbulence, 

boundary-layer flow, landing gear dynamics, 

measurement of engine effluents for pollution 

studies, noise measurements and evaluation 

of a maintenance monitoring and recording 

system. On many YF-12 flights medical researchers obtained information on the physiological and biomedical aspects of crews flying 

at sustained high speeds. Research data from 

the YF-12 program also validated analytical 

theories and wind-tunnel test techniques that 

will improve design and performance of future 

military and civil aircraft.

From February 1972 until July 1973, one 

YF-12A was used for heat loads testing in 

Dryden’s High Temperature Loads Laboratory 

(now the Thermostructures Research Facility). 

The resulting data helped improve theoretical prediction methods and computer models 

dealing with structural loads, materials, and 

heat distribution at up to 800 degrees Fahrenheit, the surface temperatures reached during 

sustained speeds of Mach 3.

SR-71 Specifications and Performance

Two Pratt and Whitney J58 axial-flow turbojets with afterburners, each producing 32,500 

pounds of thrust, powered the Blackbirds. 

Less than 20 percent of the total thrust used to 

fly at Mach 3 was produced by the engine itself, however. During high-speed cruise conditions the balance of total thrust was produced 

by the unique design of the engine inlet and 

a moveable conical spike at the front of each 

engine nacelle. Under these conditions, air entering the inlets bypassed the engines, going 

directly to the afterburners and ejector nozzles, 

thus acting as ramjets.

The airframes were built almost entirely of 

titanium and other exotic alloys to withstand 

heat generated by sustained high-speed flight. 

Capable of cruising at Mach 3 continuously for 

more than one hour at a time, the Blackbirds 

provided a unique research platform for thermal experiments because heat-soak temperatures exceeded 600 degrees Fahrenheit.

The aircraft was 107.4 feet (32.73 meters) 

long, had a wingspan of 55.6 feet (16.94 meters), and stood 18.5 feet (5.63 meters) high 

(from the ground to the top of the rudders 

EC97 44295-100
National Aeronautics and Space Administration

Dryden Flight Research Center

P.O. Box 273

Edwards, CA 93523-0273

Voice 661-276-3449 FAX 661-276-3566

NASA Facts

FS-2008-6-030-DFRC

when parked). Gross takeoff weight was about 

140,000 pounds (52,253.83 kilograms), including a fuel weight of 80,000 pounds (29,859.33 

kilograms). Aerodynamic control surfaces 

consisted of all-moving vertical tail fins above 

each engine nacelle and elevons on the outer 

wings and trailing edges between the engine 

exhaust nozzles.

NASA crews flew four Lockheed SR-71 airplanes during the 1990s. Two were used for 

research and two to support Air Force reactivation of the SR-71 for reconnaissance missions. Although the Air Force retired the Blackbirds in 1990, Congress reinstated funding for 

additional flights several years later. SR-71A 

(61-7980/NASA 844) arrived at Dryden on Feb. 

15, 1990. It was placed into storage until 1992 

and served as a research platform until its final 

flight on Oct. 9, 1999. SR-71A (61-7971/NASA 

832) arrived at Dryden on March 19, 1990, 

but was returned to Air Force inventory as the 

first aircraft was reactivated in 1995. Along 

with SR-71A (61-7967), it was flown by NASA 

crews in support of the Air Force program. 

SR-71B (61-7956/NASA 831) arrived at Dryden 

on July 25, 1991, and served as a research 

platform as well as for crew training and proficiency until October 1997.