Wide-area imaging was provided by two of Itek's Operational Objective Cameras, which provided stereo imagery across the width of the flight track, or an Itek Optical Bar Camera, which gave continuous horizon-to-horizon coverage. The CIA approved a US$96million contract for Skunk Works to build a dozen spy planes, named "A-12", on 11 February 1960. President Eisenhower had approved the use of bombers and balloons in the early 1950s for intelligence gathering, but these craft were vulnerable to antiaircraft artillery and fighter-interceptors. . [57], Air was initially compressed (and heated) by the inlet spike and subsequent converging duct between the center body and inlet cowl. Downstream of this normal shock, the air is subsonic. It set world records for altitude and speed: an absolute altitude record of 85,069 feet on July 28, 1974, and an absolute speed record of 2,193.2 miles per hour on the same day. Much of the needed material came from the Soviet Union. The Blackbird was to retrace and photograph the flightpath of the hijacked 727 from Seattle to Reno and attempt to locate any of items that Cooper was known to have parachuted with from the aircraft. The Blackbird was designed to provide reconnaissance in defended airspace while improving aircrew survivability. And the determination was that if one could take advantage of technology and develop a system that could get that data back real time that would be able to meet the unique requirements of the tactical commander." As velocity decreased, so did frictional heat. Beginning in 1980, the analog inlet control system was replaced by a digital system, which reduced unstart instances. [26], The SR-71, while much more capable than the Lockheed U-2 in terms of range, speed, and survivability, suffered the lack of a data link, which the U-2 had been upgraded to carry. NASA.gov brings you the latest images, videos and news from America's space agency. The rotating machinery produced less power, but still enough to run at 100% RPM, thus keeping the airflow through the intake constant. Marshall, Eliot, "The Blackbird's Wake", Air & Space, October/November 1990, p. 35. After a meeting with the CIA in March 1959, the design was modified to have a 90% reduction in radar cross-section. Another project stemming from the development of the A-12 was the M-21 aircraft and the D-21 drone. Morrison, Bill, SR-71 contributors, Feedback column. 61-7972, when the Astro-Inertial Navigation System (ANS) fails on a training mission and they accidentally fly into Mexican airspace, 5 February 1968: Lockheed ordered to destroy A-12, YF-12, and SR-71 tooling, 8 March 1968: First SR-71A (AF Ser. [64][65], Several exotic fuels were investigated for the Blackbird. It was found that the plane was in obvious distress and a decision was made that the Swedish Air Force would escort the plane out of the Baltic Sea. On 28 July 1976, SR-71 serial number 61-7962, piloted by then Captain Robert Helt, broke the world record: an "absolute altitude record" of 85,069 feet (25,929 m). The media transcript given to the press at the time still had the earlier RS-71 designation in places, creating the story that the president had misread the aircraft's designation. An advanced, long-range, Mach 3.2 strategic reconnaissance aircraft. 3,500lb (1,588kg) of mission equipment, Aircraft of comparable role, configuration, and era. NASA operated the two last airworthy Blackbirds until 1999. [49] Its "blue light" source star tracker, which could see stars during both day and night, would continuously track a variety of stars as the aircraft's changing position brought them into view. [131] This equates to an average speed of about Mach2.72, including deceleration for in-flight refueling. ", "SR-71 Pilot Interview Richard Graham Veteran Tales", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-86", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-99", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-123", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-129", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-132", "SR-71 Online - SR-71 Flight Manual: Section 4, Page 4-146", "First man to fly the world's fastest aircraft dies in Rancho Mirage", "SR-71 Pilot Interview Richard Graham, Veteran Tales interview at Frontiers of Flight Museum (at 1:02:55)", "Memorandum for the Chairman, Sanitization and Decontrol Working Group Black Shield Photography", "Bye Bye U-2: CIA Legend Allen Predicts End Of Manned Reconnaissance", "SPIONFLY, DEN KALDE KRIGEN - Spionfly landet i Bod", "TV: Krnvapenskra bunkern styrde flygplanen", "4 Swedish JA-37 Viggen pilots receives medals for SR-71 Blackbird rescue operation 1987 Part:1/2", "4 Swedish JA-37 Viggen pilots receives medals for SR-71 Blackbird rescue operation 1987 Part:2/2", "SR-71 World Record Speed and Altitude Flights", "A-12, YF-12A, & SR-71 Timeline of Events", "Spy Plane Sets Speed Record, Then Retires. The shock waves generated slowed the air to subsonic speeds relative to the engine. The highest altitude recorded on an SR-71 Blackbird is 25,929 meters. [38], The Blackbird's tires, manufactured by B.F. Goodrich, contained aluminum and were filled with nitrogen. Here's a list the top speed, highest and quickest distance between two points. One of the most impressive vehicles to come out of the Lockheed Skunk Works experimental and clandestine development team is the SR-71 Blackbird. The SR-71 originated in a post-World War II environment where reconnaissance was in high demand. The investigation determined that the new aircraft would need to be supersonic and have a small radar cross-section. After passing through the turbine, the exhaust, together with the compressor bleed air, entered the afterburner. On one occasion, one complete wing with engine was replaced as the easiest way to get the plane airborne again. The specialized tooling used to manufacture both the YF-12 and the SR-71 was also ordered destroyed. [107][108] The other route, from Mildenhall over the Baltic Sea, was known as the Baltic Express. YF-12A # 60-6934 Absolute Speed Over a Straight Course: 2,070.101 mph .YF-12A #60-6936 Its initial purpose would have been to conduct post-nuclear strike reconnaissance; that is, looking over the enemys situation after a nuclear exchange. Originally planned as a high . [35] Within 20 seconds the aircraft traveled 4,500 feet (1,400m), reached 240 miles per hour (390km/h), and lifted off. One was along the Norwegian west coast and up the Kola Peninsula, which contained several large naval bases belonging to the Soviet Navy's Northern Fleet. The SR-71's capability of flying at high speeds and at high altitudes made it possible for it to fly faster than any surface to air missiles that were fired at it. The U.S. military, anticipating a time . The Lockheed SR-71 Blackbird was a two-seat twin-engine long-range supersonic strategic reconnaissance aircraft produced by Lockheed Corporation. The SR-71 Blackbird cruises above Mach 3 (three times the speed of sound). [19], The outer windscreen of the cockpit was made of quartz and was fused ultrasonically to the titanium frame. 61-7956/NASA No. Eventually, a quieter, pneumatic start system was developed for use at main operating bases. [30] Metallurgical contamination was another problem; at one point, 80% of the delivered titanium for manufacture was rejected on these grounds.[31][32]. [120] Four months after the plane's retirement, General Norman Schwarzkopf Jr., was told that the expedited reconnaissance, which the SR-71 could have provided, was unavailable during Operation Desert Storm. SR-71 Blackbird spotted breaking the sound barrier at high altitude. 61-7959) in "big tail" configuration, 2728 July 1976: SR-71A sets speed and altitude records (altitude in horizontal flight: 85,068.997ft (25,929.030m) and speed over a straight course: 2,193.167 miles per hour (3,529.560km/h)), 15 January 1982: SR-71B, AF Ser. These generals were adept at communicating the value of the SR-71 to a USAF command staff and a Congress who often lacked a basic understanding of how the SR-71 worked and what it did. In other words, it was a spy plane. As space-based surveillance systems became more sophisticated and air defense systems became more effective, the Air Force chose to end the expensive program. The air slowed supersonically with a final plane shock wave at entry to the subsonic diffuser.[51]. These SR-71 photos were photographed by civilians or members/veterans of the US. On May 1, 1960, a surface-to-air missile explosion knocked down the U-2 of Gary Powers over Soviet airspace. [49], On a typical mission, the SR-71 took off with only a partial fuel load to reduce stress on the brakes and tires during takeoff and also ensure it could successfully take off should one engine fail. [15], The SR-71 designation is a continuation of the pre-1962 bomber series; the last aircraft built using the series was the XB-70 Valkyrie. Bleed tubes and bypass doors were designed into the inlet and engine nacelles to handle some of this pressure and to position the final shock to allow the inlet to remain "started". This configuration had a second seat for the weapons officer and cut back the chines along the nose in order to fit the AN/ASG-18 Fire Control System and AIM-47A missile armament. [97] These deployments were code-named "Glowing Heat", while the program as a whole was code-named "Senior Crown". Mission equipment for the reconnaissance role included signals intelligence sensors, side looking airborne radar, and a camera;[2] 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. [68], Specialized KC-135Q tankers were required to refuel the SR-71. The 1970s proved to be the most noteworthy period for the high-Mach Blackbird. Imagery gathered included supply depots, harbor installations, industrial complexes, and prisoner-of-war camps. Lockheed found that washing welded titanium requires distilled water, as the chlorine present in tap water is corrosive; cadmium-plated tools could not be used, as they also caused corrosion. Los Angeles, California, to Washington, D.C., distance 2,299.7 miles (3,701.0km), average speed 2,144.8 miles per hour (3,451.7km/h), and an elapsed time of 64 minutes 20 seconds. There were cases of the aircraft not being ready to fly again for a month due to the repairs needed. "SR-71 Blackbird." This page was last edited on 2 March 2023, at 07:27. [36] The temperature of the exterior of the windscreen reached 600F (316C) during a mission. Despite a brief revival of SR-71 flights in the mid-1990s, the program came to a final close in 1998. Show more Show more 7:16 Lockheed SR-71 Blackbird. 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. They refueled from a KC-135, accelerated. Less than two weeks . The counterargument was that the longer the SR-71 was not upgraded as aggressively as it ought to have been, the more people could say that it was obsolescent, which was in their interest as champions of other programs (a self-fulfilling bias). The Foxhound climbed at 65,676 feet where the crew. This portion of the skin was only supported by widely spaced structural ribs. The SR-71 holds a coast-to-coast speed record of 64 . No. 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. Kelly Johnson submitted his proposal for the U-2, essentially a glider with a jet engine and a panning camera in its belly. The SR-71's record setting speed and high-altitude flights helped it keep enemies at bay. It was a slow craft and visible on radar, but it compensated for these deficiencies with its high-altitude capability. Supersonic flights generally lasted no more than 90 minutes before the pilot had to find a tanker. Blackbird aircraft have been setting records since day one. These are only two of the numerous records set by the SR-71 and its cloud of Blackbirds. Much like the SR-71, the A-12 was about 30-meters (100-feet) long, had a wingspan of 17 meters (55 feet), and weighed 54,431 kilograms (120,000 pounds). Instead, the SR-71's camera systems could be located either in the fuselage chines or the removable nose/chine section. . [17] The CIA's A-12 was a better photo-reconnaissance platform than the USAF's R-12, since the A-12 flew somewhat higher and faster, and with only one pilot, it had room to carry a superior camera[14] and more instruments. The SR-71 was in duty from 1964 until 1989 and during a reactivation from 1993 until 1998. An SR-71 refueling from a KC-135Q Stratotanker during a flight in 1983. SR-71 "Blackbird". [97] During its career, this aircraft (976) accumulated 2,981 flying hours and flew 942 total sorties (more than any other SR-71), including 257 operational missions, from Beale AFB; Palmdale, California; Kadena Air Base, Okinawa, Japan; and RAF Mildenhall, UK. [18] The A-12 flew covert missions while the SR-71 flew overt missions; the latter had USAF markings and pilots carried Geneva Conventions Identification Cards. In June 1998, the U.S. Supreme Court ruled that the line-item veto was unconstitutional. Both the first SLAR and ASARS-1 were ground-mapping imaging systems, collecting data either in fixed swaths left or right of centerline or from a spot location for higher resolution. Only one crew member, Jim Zwayer, a Lockheed flight-test reconnaissance and navigation systems specialist, was killed in a flight accident. [95] The first SR-71 to enter service was delivered to the 4200th (later, 9th) Strategic Reconnaissance Wing at Beale Air Force Base, California, in January 1966.[96]. SR-71C 64-17981)[177], After completion of all USAF and NASA SR-71 operations at Edwards AFB, the SR-71 Flight Simulator was moved in July 2006 to the Frontiers of Flight Museum at Love Field Airport in Dallas, Texas. On 1 November 2013, media outlets reported that Skunk Works has been working on an unmanned reconnaissance airplane it has named SR-72, which would fly twice as fast as the SR-71, at Mach 6. Maximum speed limit was Mach 3.2, but could be raised to Mach 3.3 if the engine compressor inlet temperature did not exceed 801F (427C). Why the SR-71 Blackbird Is Such a Badass Plane; The SR-71 was the result of a requirement for a high-speed, high-altitude strategic reconnaissance aircraft. "[104] It was agreed to add $100million to the budget to return three SR-71s to service, but it was emphasized that this "would not prejudice support for long-endurance UAVs" [such as the Global Hawk]. They cost $2,300 and would generally require replacing within 20 missions. Meanwhile, the Air Force wanted a long-range interceptor aircraft that could fly long distances at triplesonic cruise speed above 21,336 (70,000 feet) to intercept enemy bombers with Hughes Falcon air-to-air missiles. We do not know whether they then went on to move across that bridge. The SR-71's specially designed engines converted to low-speed ramjets by redirecting the airflow around the core and into the afterburner for speeds greater than Mach 2.5. When the aircraft accelerated past Mach1.6, an internal jackscrew moved the spike up to 26in (66cm) inwards,[50] directed by an analog air inlet computer that took into account pitot-static system, pitch, roll, yaw, and angle of attack. Air Force and NASA. [123], The SR-71 was the world's fastest and highest-flying air-breathing operational manned aircraft throughout its career and it still holds that record. Some of this compressor flow (20% at cruise) was removed after the fourth compressor stage and went straight to the afterburner through six bypass tubes. No. For other uses, see, See the opening fly page in Paul Crickmore's book. A MiG-25 had locked a missile on the damaged SR-71, but as the aircraft was under escort, no missiles were fired. Such generals had an interest in believing, and persuading the services and the Congress, that the SR-71 had become either entirely or almost entirely redundant to satellites, U-2s, incipient UAV programs, and an alleged top-secret successor already under development. "If we had one sitting in the hangar here and the crew chief was told there was a mission planned right now, then 19 hours later it would be safely ready to take off. [19] It is a common misconception that the planes refueled shortly after takeoff because the jet fuel leaked. [53] After wind tunnel testing and computer modeling by NASA Dryden test center,[54] Lockheed installed an electronic control to detect unstart conditions and perform this reset action without pilot intervention. Of 11 successive designs drafted in a span of 10 months, "A-10" was the front-runner. Hinckley, UK: AeroFax-Midland Publishing, 2002. The U.S. Air Force had played a huge role in supporting the CIAs A-12 program in terms of money, aerial refueling support, use of its facilities at Kadena Air Force Base, and various transport. In actuality, the YF-12 was the twin-seat version of the top-secret single-seat Lockheed A-12, and its design became the forerunner of the highly sophisticated SR-71 Blackbird strategic reconnaissance aircraft. [3] In 1976, the SR-71 Blackbird flew at a sustained altitude of 85,069 feet with top speeds of 2,193 MPH, setting records of top speed and altitude that haven't been beaten to this day. [91][92] The SR-71 reached a top speed of Mach 3.4 during flight testing,[93][94] with pilot Major Brian Shul reporting a speed in excess of Mach 3.5 on an operational sortie while evading a missile over Libya. [33] The heat would have caused a smooth skin to split or curl, whereas the corrugated skin could expand vertically and horizontally and had increased longitudinal strength. A general misunderstanding of the nature of aerial reconnaissance and a lack of knowledge about the SR-71 in particular (due to its secretive development and operations) was used by detractors to discredit the aircraft, with the assurance given that a replacement was under development. The A-12 is a single-seat, twin-engine, twin-tail design, manufactured of a titanium alloy. [137] Unmanned aerial vehicles (UAVs) are also used for aerial reconnaissance in the 21st century, being able to overfly hostile territory without putting human pilots at risk, as well as being smaller and harder to detect than manned aircraft. The fly-over orbit of spy satellites may also be predicted and can allow assets to be hidden when the satellite passes, a drawback not shared by aircraft. [121] Rear Admiral Thomas F. Hall addressed the question of why the SR-71 was retired, saying it was under "the belief that, given the time delay associated with mounting a mission, conducting a reconnaissance, retrieving the data, processing it, and getting it out to a field commander, that you had a problem in timelines that was not going to meet the tactical requirements on the modern battlefield. In the early years of operation, the analog computers would not always keep up with rapidly changing flight environmental inputs. Its first operational mission was over Vietnam and subsequent missions were flown one to three times per week. In 1976, the Lockheed SR-71 Blackbird broke the world's record for sustained altitude in horizontal flight at 25,929 meters (85,069 feet). Attempts to add a datalink to the SR-71 were stymied early on by the same factions in the Pentagon and Congress who were already set on the program's demise, even in the early 1980s. Peak speeds during this flight were likely closer to the declassified top speed of over Mach3.2. [11] That same day SR-71 serial number 61-7958 set an absolute speed record of 1,905.81 knots (2,193.2mph; 3,529.6km/h), approximately Mach3.3. "Jet Propulsion for Aerospace Applications" second edition, Hesse and Mumford, Pitman Publishing Corporation, Library of Congress Catalog Card Number: 64-18757, p375, "F-12 Series Aircraft Propulsion System Performance and Development" David Campbell, J. Cooper. [105] Five flights were attempted but on each occasion no photographs of the flight path were obtained due to low visibility.[106]. The air then entered the engine compressor. Twelve SR-71s were lost and one pilot died in accidents during the aircraft's service career. [71][verification needed], Before takeoff, a primary alignment brought the ANS's inertial components to a high degree of accuracy. This close-up, head-on view of NASA's SR-71A Blackbird in flight shows the aircraft with an experimental test fixture mounted on the back of the airplane. Kelly Johnson answered the call. No. European operations were from RAF Mildenhall, England. [46] The angle of incidence of the delta wings could be reduced for greater stability and less drag at high speeds, and more weight carried, such as fuel. On 28 July 1976, SR-71 serial number 61-7962, piloted by then Captain Robert Helt, broke the world record: an "absolute altitude record" of 85,069 feet (25,929 m). The aircraft is silhouetted against the sunset. On 26 April 1971, 61-7968, flown by majors Thomas B. Estes and Dewain C. Vick, flew over 15,000 miles (24,000km) in 10 hours and 30 minutes. On July 28, 1976, an SR-71A set an Altitude in Horizontal Flight record at 85,068.997 feet. [6] 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. 3. The SR-71 had a radar cross-section (RCS) around 110sqft (10m2). This proportion increased progressively with speed until the afterburner provided all the thrust at about Mach 3. The Blackbirds owes its success to the continuum of aircraft that came before it. NASA was the final operator of the Blackbird, who used it as a research platform, retiring it in 1999. Its stealthy design reduced its radar signature, and if it were fired upon by a surface-to-air missile, its evasive action was to simply accelerate and outfly the assailant. 28, 1976 in fact, SR-71 61-7962 set two world records for its class an absolute speed record of 2,193.167 mph and an absolute altitude record of 85,068.997 feet (although SR-71 61-7953 unofficially reached 86,700 feet in 1968). Graham, a former 1st-SRS and 9th-SRW commander, presented in 1996 what he viewed as a factual summary, not an opinion, of how the SR-71 provided some intelligence capabilities that none of its alternatives (such as satellites, U-2s, and UAVs) were providing in the 1990s (when the SR-71 was retired and then re-retired from Air Force reconnaissance duty. Still-active USAF pilots and Reconnaissance Systems Officers (RSOs) who had worked with the aircraft were asked to volunteer to fly the reactivated planes. It is the integration of strategic and tactical. Kloesel, Kurt J., Nalin A. Ratnayake and Casie M. Clark. [12], The A-12 first flew at Groom Lake (Area 51), Nevada, on 25 April 1962. Thirteen were built; two variants were also developed, including three of the YF-12 interceptor prototype, and two of the M-21 drone carrier. The SR-71 was one of several spy airplanes built to venture into enemy territory without being shot down or even detected. [26] Dick Cheney told the Senate Appropriations Committee that the SR-71 cost $85,000 per hour to operate. [4][5] In 1989, the USAF retired the SR-71 largely for political reasons; several were briefly reactivated during the 1990s before their second retirement in 1998. [66] However, the amount of fuel that leaked was not enough to make the refueling necessary; the planes refueled because the maximum speeds of the aircraft were only possible with aerial refueling. [49], At the front of each inlet, a pointed, movable inlet cone called a "spike" was locked in its full forward position on the ground and during subsonic flight. 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 aircraft flew at an altitude of over 80,000 feet (24,000 m) and at speeds over 2,190 miles per hour (3,520 km/h). Thus, there are doubts that the US has abandoned the concept of spy planes to complement reconnaissance satellites. A high altitude jet aircraft used by the CIA and the US Air Force during the cold war. Moving the spike tip drew the shock wave riding on it closer to the inlet cowling until it touched just slightly inside the cowling lip. Cockpit section survived and located at the, 13 June 1962: SR-71 mock-up reviewed by the USAF, 30 July 1962: J58 completes pre-flight testing, 28 December 1962: Lockheed signs contract to build six SR-71 aircraft, 25 July 1964: President Johnson makes public announcement of SR-71, 29 October 1964: SR-71 prototype (AF Ser. [56], The SR-71 was powered by two Pratt & Whitney J58 (company designation JT11D-20) axial-flow turbojet engines. [112][113][114], On 29 June 1987, an SR-71 was on a mission around the Baltic Sea to spy on Soviet postings when one of the engines exploded. ", "Exclusive: Skunk Works Reveals SR-71 Successor Plan", "Skunk Works reveals Mach 6.0 SR-72 concept", "EXCLUSIVE: Secret New UAS Shows Stealth, Efficiency Advances", "There Can Be Only One: The Saga of the Only SR-71C Ever Built", "U-2 and SR-71 Units, Bases and Detachments", "Aircraft On Display: Lockheed SR-71A Blackbird. Unofficially, SR-71 pilot Brian Shul states in his book The Untouchables that he flew in excess of Mach 3.5 on 15 April 1986 over Libya to evade a missile. Water bottles had long straws which crewmembers guided into an opening in the helmet by looking in a mirror. On 6 March 1990, Lt. Col. Raymond E. Yeilding and Lt. Col. Joseph T. Vida piloted SR-71 S/N 61-7972 on its final Senior Crown flight and set four new speed records in the process: These four speed records were accepted by the National Aeronautic Association (NAA), the recognized body for aviation records in the United States. 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. 61-7950) delivered to, 22 December 1964: First flight of the SR-71, with Lockheed test pilot Robert J "Bob" Gilliland at Palmdale, 21 July 1967: Jim Watkins and Dave Dempster fly first international sortie in SR-71A, AF Ser. Air passing through the turbojet was compressed further by the remaining five compressor stages and then fuel was added in the combustion chamber. 11, November 1974. On landing, the canopy temperature was over 572F (300C). Just to put the speed of the SR-71 into . The one record that it still holds is a cross-country flight, zipping from Los Angeles to Washington, D.C. in just 64 minutes 20 seconds. During one mission, SR-71 pilot Brian Shul flew faster than usual to avoid multiple interception attempts; afterward, it was discovered that this had reduced fuel consumption. Goodall, James and Jay Miller. [citation needed], Flying at 80,000ft (24,000m) meant that crews could not use standard masks, which could not provide enough oxygen above 43,000ft (13,000m). This unusual instrument projected a barely visible artificial horizon line across the top of the entire instrument panel, which gave the pilot subliminal cues on aircraft attitude. Several aircraft have exceeded this altitude in zoom climbs, but not in sustained flight. Finally, scramjets with supersonic combustion cover the range of high supersonic to hypersonic speeds. The primary consumers of this intelligence were the CIA, NSA, and DIA. [29] To control costs, Lockheed used a more easily worked titanium alloy which softened at a lower temperature. Created by Lockheed's brilliant designer Kelly Johnson, the SR-71 Blackbird is one of the most legendary aircraft to emerge from the famous "Skunk Works". Flights often lasted more than six hours and covered more than 11,265 kilometers (7,000 square miles). [11][127][128][129] Several aircraft have exceeded this altitude in zoom climbs, but not in sustained flight. Early A-12s were tested with Pratt & Whitney J75 engines in 1961, but were retrofitted with J58 engines optimized to meet the speed rating of Mach 3.2 once they became available in 1963. If internal pressures became too great and the spike was incorrectly positioned, the shock wave would suddenly blow out the front of the inlet, called an "inlet unstart". The gone but not forgotten Lockheed SR-71 Blackbird takes flight at sunset on its way to making a Mach 3.2 thunder run. [103], While deployed at Okinawa, the SR-71s and their aircrew members gained the nickname Habu (as did the A-12s preceding them) after a pit viper indigenous to Japan, which the Okinawans thought the plane resembled. The SR-71 entered service in January 1966. On September 1, 1974, it set a speed and time Cesium-based fuel additives were used to somewhat reduce exhaust plumes' visibility to radar, although exhaust streams remained quite apparent. However, another view held by various officers and legislators is that the SR-71 program was terminated owing to Pentagon politics, and not because the aircraft had become obsolete, irrelevant, too hard to maintain, or unsustainably expensive.
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