Cold War: Lockheed SR-71 Blackbird

SR-71 Blackbird in flight
Lockheed SR-71 Blackbird. US Air Force

SR-71A Blackbird - Specifications:

General

  • Length: 107 ft. 5 in.
  • Wingspan: 55 ft. 7 in.
  • Height: 18 ft. 6 in.
  • Wing Area: 1,800 sq. ft.
  • Empty Weight: 67,500 lbs.
  • Loaded Weight: 170,000 lbs.
  • Crew: 2

Performance

  • Power Plant: 2 × Pratt & Whitney J58-1 continuous-bleed afterburning turbojets
  • Range: 2,900 nautical miles
  • Max Speed: Mach 3.2+ (2,200 mph)
  • Ceiling: 85,000 ft.

SR-71 Blackbird - Design & Development:

In the late 1950s, Lockheed began preliminary development for a new spy plane to replace its earlier U-2.

Overseen by Clarence "Kelly" Johnson's Skunk Works unit, the project sought an increase in speed while reducing the aircraft's radar cross-section. As it was intended for overflights of the Soviet Union, the aircraft was designed to travel at extremely high altitude at a speed in excess of Mach 3. This project ultimately produced the ground-breaking A-12 which was selected for service with the Central Intelligence Agency.

In the early 1960s, the US Air Force began seeking a new aircraft for the reconnaissance/strike role. Though they considered using a modified version of the XB-70 Valkyrie, they instead elected to pursue a variant of the CIA's A-12. Responding to the USAF's demands, Lockheed began a re-design of the A-12 which included a lengthening of the aircraft to increase range, the inclusion of a second seat in the cockpit, and an expansion of the sensor and camera capabilities. These modifications also required altering the aircraft's distinctive chines.

Initially dubbed R-12, the new type ultimately received the designation SR-71. Due to the aircraft's intended high speed, it was largely constructed of titanium to withstand the excessive temperatures that occur at supersonic speeds. In addition, as the SR-71's fuselage panels would expand due to the high operational temperatures, they were made to fit loosely when the aircraft was on the ground.

As a result, it was known to leak fuel before takeoff. To power the SR-71, Lockheed installed two Pratt & Whitney J58 turbojets capable of generating 35,000 pounds of thrust each.

Using specially-designed JP-7 jet fuel, the J58 featured a translating (moveable) spike in the intake to control airflow during flight. As speed increased, the spike retracted to increase the amount of air reaching the engine. As JP-7 was selected due to its high ignition point, a requirement in a high temperature flight, the SR-71 required an external engine and shots of triethylborane to start its engines. To ensure crew survivability at Mach 3+ and 80,000 feet, SR-71 crews wore specially-designed full pressure suits during missions. These also provided vital protection in case of the need to eject.

SR-71 Blackbird - Sensors & Instruments:

Due the nature of the SR-71's intended mission, pinpoint navigation was required. To meet this need, Lockheed utilized Northrop's NAS-14/21 Astro-Inertial Navigation System which corrected inertial navigation errors with celestial observations. For fulfilling its mission, the SR-71 carried a wide array of cameras and sensors. These evolved over the aircraft's service life and included cameras, infrared imaging systems, side-looking radar, advanced synthetic aperture radar, and electronic intelligence gathering systems.

SR-71 Blackbird - Operational History:

Dubbed the Blackbird, the first SR-71 flew on December 22, 1964. Production soon moved forward with Lockheed building 32 of the type. Entering service with the 4200th (late 9th) Strategic Reconnaissance Wing in January 1966, the SR-71 first deployed overseas in March 1968. Arriving at Kadena Air Base in Okinawa, the SR-71 conducted missions over North Vietnam during the Vietnam War. During the aircraft's time in Okinawa, its crews gave it the nickname Habu in reference to a pit viper indigenous to the island.

That same year, Secretary of Defense Robert McNamara ordered the specialized tooling used to manufacture the aircraft destroyed. Though this was part of the original contract, it limited to Blackbird force to the 32 aircraft that had been built. The SR-71 remained in constant use by the USAF until 1989.

Due to the nature of the aircraft's activities, the bulk of its missions remained classified. An expensive and difficult aircraft to maintain, the SR-71 never developed a dedicated support within the USAF or Congress. As a result, acquiring funding for the aircraft was difficult from the 1970s forward.

Critics of the SR-71 typically cited the aircraft's cost and its lack of a data link which prevented the intelligence it gathered from being used in real time. In addition, parts were no longer available forcing ground crews to cannibalize other Blackbirds to keep a small number flying. Others questioned the need for the aircraft as reconnaissance satellites were developed to fulfill a similar role. This mix of justifications led to the aircraft being retired by the USAF in October 1989.

This decision was questioned a year later when coalition forces were unable to obtain the type of intelligence the SR-71 could have provided during the Gulf War. Though not making a decision then, Congress began to reexamine the aircraft in 1993, especially as no effective replacement had been developed. As a result of the hearing, the SR-71 was re-activated. This move met some resistance from the USAF which had not planned for maintaining the aircraft and desired to direct funding to other programs, including reconnaissance unmanned aerial vehicles.

With the activation of the SR-71, Lockheed upgraded several airframes. Among the enhancements was the addition of a data link which could provide information in near real time.

Rejoining the 9th Reconnaissance Wing, the SR-71's return proved short-lived. Facing resistance from the USAF and Clinton Administration, the Blackbird was permanently retired in late 1998. While the USAF quickly dispensed with the aircraft, NASA continued to fly two Blackbirds in a research role for another year.

During its career, the SR-71 set several notable speed records including New York-London (1 hr., 54 min., 56.4 sec.), Los Angeles, Ca. to Washington, D.C. (64 min., 20 sec.), and West Coast to East Coast (67 min, 54 sec.). Also, in 1976 the SR-71 set an absolute altitude record by cruising at 85,069 as well as an absolute speed record of 2,193.2 mph. During its service life, no SR-71 was lost due to hostile action though numerous attempts were made. The standard evasion maneuver for the aircraft was to simply accelerate to outrun the threat. In its career, twelve Blackbirds were lost in accidents resulting in one fatality.

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Hickman, Kennedy. "Cold War: Lockheed SR-71 Blackbird." ThoughtCo, Feb. 24, 2016, thoughtco.com/cold-war-lockheed-sr-71-blackbird-2361062. Hickman, Kennedy. (2016, February 24). Cold War: Lockheed SR-71 Blackbird. Retrieved from https://www.thoughtco.com/cold-war-lockheed-sr-71-blackbird-2361062 Hickman, Kennedy. "Cold War: Lockheed SR-71 Blackbird." ThoughtCo. https://www.thoughtco.com/cold-war-lockheed-sr-71-blackbird-2361062 (accessed December 11, 2017).