The Lockheed SR-71 Blackbird is a long-range, high-altitude, Mach 3+ strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporation.
It was operated by both the United States Air Force (USAF) and NASA.
The SR-71 was developed as a black project from the Lockheed A-12 reconnaissance aircraft during the 1960s by Lockheed’s Skunk Works division.
American aerospace engineer Clarence “Kelly” Johnson was responsible for many of the aircraft’s innovative concepts.
The shape of the SR-71 was based on that of the A-12, which was one of the first aircraft to be designed with a reduced radar cross-section.
Initially, a bomber variant of the A-12 was requested by Curtis LeMay, before the program was focused solely on reconnaissance.
Mission equipment for the reconnaissance role included signals intelligence sensors, side looking airborne radar, and a camera; the SR-71 was both longer and heavier than the A-12, allowing it to hold more fuel as well as a two-seat cockpit.
The SR-71 entered service in January 1966.
During aerial reconnaissance missions, the SR-71 operated at high speeds and altitudes (Mach 3.2 and 85,000 feet, 25,900 meters), allowing it to outrace or entirely avoid threats.
If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outpace the missile.
On average, each SR-71 could fly once per week due to the extended turnaround required after mission recovery.
A total of 32 aircraft were built; 12 were lost in accidents with none lost to enemy action.
During 1989, the USAF retired the SR-71 largely for political reasons; several were briefly reactivated during the 1990s before their second retirement in 1998.
NASA was the final operator of the Blackbird, who used it as a research platform, and was retired in 1999.
Since its retirement, the SR-71’s role has been taken up by a combination of reconnaissance satellites and unmanned aerial vehicles (UAVs); a proposed UAV successor, the SR-72, is under development by Lockheed Martin, and scheduled to fly in 2025.
The SR-71 has several nicknames, including “Blackbird” and “Habu”.
As of 2022 the SR-71 holds the world record it set in 1976 as the fastest air-breathing manned aircraft, previously held by the related Lockheed YF-12.
The SR-71 was designed for flight at over Mach 3 with a flight crew of two in tandem cockpits, with the pilot in the forward cockpit and the reconnaissance systems officer operating the surveillance systems and equipment from the rear cockpit and directing navigation on the mission flight path.
The SR-71 was designed to minimize its radar cross-section, an early attempt at stealth design.
Finished aircraft were painted a dark blue, almost black, to increase the emission of internal heat and to act as camouflage against the night sky.
The dark colour led to the aircraft’s nickname “Blackbird”.
While the SR-71 carried radar countermeasures to evade interception efforts, its greatest protection was its combination of high altitude and very high speed, which made it almost invulnerable.
Along with its low radar cross-section, these qualities gave a very short time for an enemy surface-to-air missile (SAM) site to acquire and track the aircraft on radar.
By the time the SAM site could track the SR-71, it was often too late to launch a SAM, and the SR-71 would be out of range before the SAM could catch up to it.
If the SAM site could track the SR-71 and fire a SAM in time, the SAM would expend nearly all of the delta-v of its boost and sustainer phases just reaching the SR-71’s altitude; at this point, out of thrust, it could do little more than follow its ballistic arc.
Merely accelerating would typically be enough for an SR-71 to evade a SAM; changes by the pilots in the SR-71’s speed, altitude, and heading were also often enough to spoil any radar lock on the plane by SAM sites or enemy fighters.
At sustained speeds of more than Mach 3.2, the plane was faster than the Soviet Union’s fastest interceptor, the Mikoyan-Gurevich MiG-25, which also could not reach the SR-71’s altitude.
During its service life, no SR-71 was ever shot down.
SR-71A was the main production variant.
SR-71B was a trainer variant.
SR-71C was a hybrid trainer aircraft composed of the rear fuselage of the first YF-12A and the forward fuselage from an SR-71 static test unit.
The YF-12 had been wrecked in a 1966 landing accident.
This Blackbird was seemingly not quite straight and had a yaw at supersonic speeds.
107 ft 5 in (32.74 m)
55 ft 7 in (16.94 m)
18 ft 6 in (5.64 m)
16 ft 8 in (5 m)
37 ft 10 in (12 m)
1,800 sq ft (170 m2)
67,500 lb (30,617 kg)
152,000 lb (68,946 kg)
Max take-off weight
172,000 lb (78,018 kg)
12,219.2 US gal (10,174.6 imp gal; 46,255 l) in 6 tank groups (9 tanks)