Science Behind The Fastest Lockheed SR-71 Blackbird

by Anisha Singh
Science Behind The Fastest Lockheed SR-71 Blackbird

The SR-71 Blackbird is the fastest Aircraft that is propelled by air-breathing engines. The SR-71 was developed as a black project during the 1960s by Lockheed’s Skunk Works division. The existence of SR-71 was made public in 1964. In January 1966 it entered the United States Air Force(USAF) service.

Lockheed SR-71 Blackbird

Lockheed SR-71 Blackbird. Image Credit: Wikipedia

Inspiration and Development of the SR-71 Blackbird

The inspiration for the SR-71 Blackbird stemmed from its predecessor, the A-12, another aircraft from the Blackbird family. The A-12 was notable for its reduced radar cross-section, a pioneering feature at the time. Lockheed’s Skunk Works division envisioned an advanced aircraft that could fly faster and at higher altitudes than any other, while also maintaining a minimal radar signature. This vision led to the development of the SR-71 Blackbird.

Design and Features of the SR-71

The SR-71 was engineered for sustained flight at speeds exceeding Mach 3. It featured two tandem cockpits: the pilot occupied the forward cockpit, while the reconnaissance systems officer managed surveillance equipment and navigation from the rear cockpit. The aircraft was coated in a dark blue, almost black paint, which served a dual purpose: it acted as camouflage in the night sky and helped dissipate internal heat. This distinctive coloration earned the aircraft its nickname, “Blackbird.”

Enhancements and Testing

Despite the Blackbird’s small radar profile, there were concerns about potential advancements in Soviet radar technology. To address this, the SR-71 underwent modifications to further minimize its radar cross-section. The engines were repositioned to a subtler mid-wing location, and the paint was augmented with radar-absorbing materials. Following these modifications, a full-scale model of the Blackbird was subjected to extensive radar testing at a secret Skunk Works facility in the Nevada desert, ensuring its effectiveness in evading detection.

The Science Behind SR-71 Blackbird


Pratt and Whitney J58 Engine. Image Credit: Wikipedia

Two Pratt & Whitney J58 turbojet engines powered the SR-71. These were most efficient at the speed of Mach 3.2. It was able to produce a static thrust of 32,500 lbf (145 kN).

Initially, the air underwent heating and compression through the inlet spike and subsequent converging duct. The converging duct was strategically placed between the center body and the inlet cowl. The shock waves generated by it slowed the air to subsonic speeds relative to the engine. The air then entered the engine compressor. Some of this compressor flow (20% at cruise) was redirected straight to the afterburner through a network of six bypass tubes. The remaining five compressor stages were compressing the air passing through the turbojet further. Simultaneously, fuel injection occurred within the combustion chamber, initiating the combustion process. In the afterburner, the exhaust gases from the turbine, along with the compressed airflow from the compressor, underwent further combustion to enhance thrust output.

Due to the temperature rising from the intake compression at around Mach 3, the temperature of the engine compressor also rises. Therefore, the allowable fuel flow was decreased since the turbine temperature limit remained constant. However, maintaining a steady 100% RPM (Revolutions Per Minute) the rotating machinery continued to operate, thus ensuring a consistent airflow.

Flight Airship Record

Fédération Aéronautique Internationale(FAI) defines air speed record as the highest speed attained by an aircraft of a particular class.

SR-71 Cockpit

The Tandem of two Cockpit. Image Credit: Wright-PattersonAirForceBase

Hence, with a speed of 3,530 km/h (2,190 mph), the Lockheed SR-71 Blackbird holds the official Air Speed Record for a crewed Airbreathing jet engine aircraft. Eldon W. Joersz and George T. Morgan Jr. set the record on 28 July 1976 near Beale Air Force Base, California, USA. The takeoff and landing were unassisted on conventional runways. In The Untouchables, Brian Shul, a pilot of SR-71 claimed that he flew more than Mach 3.5 on 15 April 1986, over Libya, to avoid a Missile.

Operational History of Blackbird

The Fastest Speed Recorded of SR-71

The Fastest Speed Recorded by SR-71

In December 1964, at USAF Plant 42 in California, USA, SR-71 took its first flight, which Bob Gilliland piloted. During flight testing, it reached the top speed of Mach 3.4. 

The SR-71 Blackbird flew its first operational mission in Okinawa, Japan on March 21, 1968. This took place in Kadena Airbase situated in Okinawa. However, the Blackbird needed a full day to be able to take the next flight, even in perfect conditions. It required to be repaired and maintained every once a week after a mission.

The crew members and SR-71 gained the nickname of Habu, after a native pit viper in Japan when the Sr-71 was deployed at Okinawa.

Operational Achievements for the entire Blackbird series in the 1990s included:

  • Mission sorties flown- 3,551
  • Total sorties flown- 17,300
  • Mission flight hours- 11,008
  • Total flight hours- 53,490
  • Mach 3 time (missions)- 2,752 hours
  • Mach 3 time (total)- 11,675 hours

The Mikoyan-Gurevich MiG-25 (the fastest interdict of the Soviet Union), was also unable to match the high altitude of SR-71. It was faster than the Mikoyan-Gurevich MiG-25 when it reached Mach 3.2.

Unfortunately, One crew member Jim Zwayers, who was a flight-test surveillance and navigation systems specialist, at Lockheed died in a crash. Everyone else who flew the SR-71 either ejected safely or exited the plane on the ground before it became dangerous.


As of now, we have learned that The Lockheed Sr-71 Blackbird holds the record for the fastest plane which operated from the 1960s till the 1990s. It was one of the most successful inventions of that time. The USA benefited from the features of SR-71 against the Soviet Union. It was developed in such a way that it could gather information from a high altitude without getting detected. The great operational background and remarkable achievements in speed, altitude, and capabilities of SR-71 have secured its place in aviation history

Frequently Asked Questions(FAQ)

  • How many SR-71s were built?
    Ans: Only 32 SR-71s were built.
  • How high was it capable of flying and was it ever shot down?
    Ans: It was able to fly around 80,000 feet(24,000 meters). Speed and altitude kept it from being shot down. The special paint also helped it radiate heat and avoid radar detection.
  • What was the purpose of building it and why did it shut down?
    Ans: It was created to gather information and take photos of enemy territory by infiltrating it from a high altitude. However, it was retired because of the development of spy satellites and the cost of maintenance was also very high.


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