sr 71 blackbird altitude

[40], The second operational aircraft[41] designed around a stealth aircraft shape and materials, after the Lockheed A-12,[41] the SR-71 had several features designed to reduce its radar signature. The 1960 downing of Francis Gary Powers's U-2 underscored the aircraft's vulnerability and the need for faster reconnaissance aircraft such as the A-12. [12], The A-12 first flew at Groom Lake (Area 51), Nevada, on 25 April 1962. Experience gained from the A-12 program convinced the Air Force that flying the SR-71 safely required two crew members, a pilot and a Reconnaissance Systems Officer (RSO). As Jim Goodall points herein, A-12 is known to have reached 96,200ft (39321m al. An SR-71 was used domestically in 1971 to assist the FBI in their manhunt for the skyjacker D.B. The event had been classified for over 30 years, and when the report was unsealed, data from the NSA showed that multiple MiG-25s with the order to shoot down the SR-71 or force it to land, had started right after the engine failure. Central Intelligence Agency", "The Advent, Evolution, and New Horizons of United States Stealth Aircraft. Air passing through the turbojet was compressed further by the remaining five compressor stages and then fuel was added in the combustion chamber. [81][83], Over its operational life, the Blackbird carried various electronic countermeasures (ECMs), including warning and active electronic systems built by several ECM companies and called Systems A, A2, A2C, B, C, C2, E, G, H, and M. On a given mission, an aircraft carried several of these frequency/purpose payloads to meet the expected threats. Beginning in 1980, the analog inlet control system was replaced by a digital system, which reduced unstart instances. 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). The J58s were retrofitted as they became available, and became the standard engine for all subsequent aircraft in the series (A-12, YF-12, M-21), as well as the SR-71. Due to budget concerns, this model never went into production. [25][26] The SR-71 was designed to minimize its radar cross-section, an early attempt at stealth design. [60], At around Mach3, the temperature rise from the intake compression, added to the engine compressor temperature rise, reduced the allowable fuel flow because the turbine temperature limit did not change. Only one crew member, Jim Zwayer, a Lockheed flight-test reconnaissance and navigation systems specialist, was killed in a flight accident. [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. Blackbird Aircraft Records 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 had a radar cross-section (RCS) around 110sqft (10m2). The SR-71 originally included optical/infrared imagery systems; side-looking airborne radar (SLAR);[74] electronic intelligence (ELINT) gathering systems;[75] defensive systems for countering missile and airborne fighters;[76][77][78][79] and recorders for SLAR, ELINT, and maintenance data. Congress reauthorized the funds, but, in October 1997, President Bill Clinton attempted to use the line-item veto to cancel the $39million allocated for the SR-71. 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. US Air Force supersonic aircraft, 19641998, "SR-71" redirects here. Imagery gathered included supply depots, harbor installations, industrial complexes, and prisoner-of-war camps. However, a bomber variant of the Blackbird was briefly given the B-71 designator, which was retained when the type was changed to SR-71. Swedish Air Force fighter pilots have managed to lock their radar on an SR-71 on multiple occasions within shooting range. No. Originally planned as a high . [8] As of 2023[update] 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. Very often an aircraft would return with rivets missing, delaminated panels or other broken parts such as inlets requiring repair or replacement. 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. This page was last edited on 2 March 2023, at 07:27. Some secondary references use incorrect 64- series aircraft serial numbers (e.g. How Swedish Viggen Fighter Jet Caught SR-71 Blackbird Spy Plane Aerodynamicists initially opposed the concept, disparagingly referring to the aircraft as a Mach 3 variant of the 1920s-era Ford Trimotor, which was known for its corrugated aluminum skin. Lockheed SR-71 Blackbird - Simple English Wikipedia, the free encyclopedia The SR-71 holds a coast-to-coast speed record of 64 . Rescue parties were sent in to repair the planes before leaving. 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. [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]. The addition of chines also allowed the removal of the planned canard foreplanes. Major Jerry Crew, an RSO, told Air & Space/Smithsonian that he used a jammer to try to confuse surface-to-air missile sites as their crews tracked his airplane, but once his threat-warning receiver told him a missile had been launched, he switched off the jammer to prevent the missile from homing in on its signal. Eventually, a quieter, pneumatic start system was developed for use at main operating bases. With your help, we can continue to preserve and safeguard the worlds most comprehensive collection of artifacts representing the great achievements of flight and space exploration. Related: Here Are The Most Terrifying Aircraft Ever Used By The Military Before the July speech, LeMay lobbied to modify Johnson's speech to read "SR-71" instead of "RS-71". [N 2] This USAF version was longer and heavier than the original A-12 because it had a longer fuselage to hold more fuel. [N 4] The challenges posed led Lockheed to develop new fabrication methods, which have since been used in the manufacture of other aircraft. [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. [104], Congress's disappointment with the lack of a suitable replacement for the Blackbird was cited concerning whether to continue funding imaging sensors on the U-2. [28] During its service life, no SR-71 was ever shot down. Kansas City, Missouri, to Washington, D.C., distance 942 miles (1,516km), average speed 2,176 miles per hour (3,502km/h), and an elapsed time of 25 minutes 59 seconds. [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. [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. 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. The SR-71 was the world's fastest and highest-flying operational manned aircraft throughout its career. SR-71 Blackbird Speed and Altitude Records - wvi.com 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. [22], In 1968, Secretary of Defense Robert McNamara canceled the F-12 interceptor program. The Lockheed SR-71 Blackbird was a two-seat twin-engine long-range supersonic strategic reconnaissance aircraft produced by Lockheed Corporation. The aircraft, however, was detected on radar as soon as overflights began and it was only a matter of time before one would be intercepted. Setting Records with the SR-71 Blackbird - National Air and Space Museum The SR-71 was in duty from 1964 until 1989 and during a reactivation from 1993 until 1998. The tanker also had special fuel systems for moving JP-4 (for the KC-135Q itself) and JP-7 (for the SR-71) between different tanks. [33] In practice, the Blackbird would burn somewhat conventional JP-7, which was difficult to ignite. "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. NASA released video footage of the SR-71 Blackbird, the high-altitude recon aircraft capable of reaching speeds over Mach 3. 61-7978) arrives at, 21 March 1968: First SR-71 (AF Ser. 61-7956, flies its 1,000th sortie, 21 April 1989: SR-71, AF Ser. On September 1, 1974, Major James Sullivan and his backseater, Major Noel F. Widdifield, set a speed record in SR-71A serial no. Later start carts used Chevrolet big-block V8 engines. The U.S. military, anticipating a time . "Lockheed's SR-71 'Blackbird' Family A-12, F-12, M-21, D-21, SR-71". On 29 November 2018, the four Swedish pilots involved were awarded medals from the USAF.[116][117]. Pic of the Day: SR-71 Blackbird, A Profile in Speed | SOFREP [33], Some SR-71s featured red stripes to prevent maintenance workers from damaging the thin, fragile skin located near the center of the fuselage. In the Blackbird, mission success . Quote from Reg Blackwell, SR-71 pilot, interviewed for "Battle Stations" episode "SR-71 Blackbird Stealth Plane", first aired on History Channel 15 December 2002. NASA Released Rare Footage Of The SR-71 - YouTube Named Blackbird due to its unique blue to black color, this aircraft would set numerous world records for speed and altitude. [11][129][130] SR-71 pilot Brian Shul states in his book The Untouchables that he flew in excess of Mach3.5 on 15 April 1986 over Libya to evade a missile.[95]. [42] Drawing on early studies in radar stealth technology, which indicated that a shape with flattened, tapering sides would reflect most energy away from a radar beam's place of origin, engineers added chines and canted the vertical control surfaces inward. "[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]. Absolute Altitude: 80,257.86 ft (24,390 meters). [123], Retired USAF Colonel Jay Murphy was made the Program Manager for Lockheed's reactivation plans. No. The primary consumers of this intelligence were the CIA, NSA, and DIA. Retired USAF Colonels Don Emmons and Barry MacKean were put under government contract to remake the plane's logistic and support structure. ", "SR-71 Online - SR-71 Flight Manual: Section 1, Page 1-20", "SR-71A-1 Flight Manual, Section IV, p. 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. American leaders needed to know about the Soviet Unions nuclear capability, ICBM program, and military installations. However, the USAF refused to spend the money. [104] In 1996, the USAF claimed that specific funding had not been authorized, and moved to ground the program. These were not a feature on the early A-3 design; Frank Rodgers, a doctor at the Scientific Engineering Institute, a CIA front organization, discovered that a cross-section of a sphere had a greatly reduced radar reflection, and adapted a cylindrical-shaped fuselage by stretching out the sides of the fuselage. Crickmore, Paul F. "Lockheed's Blackbirds A-12, YF-12 and SR-71A". [26] Graham said that the last-mentioned one was only a sales pitch, not a fact, at the time in the 1990s. Reconnaissance aircraft. Clarence Kelly Johnsonand Francis Gary Powers have a discussion with an early U-2 aircraft behind them. Myagkiy and its Weapons System Officer (WSO) were able to achieve a SR-71 lock on at 52,000 feet and at a distance of 120 Km from the target. The squadron finally closed in mid-1990, and the aircraft were distributed to static display locations, with a number kept in reserve storage.[26]. FLYING Classics: Lockheed Created the 'Impossible' SR-71 Blackbird to It decelerates further in the divergent duct to give the required speed at entry to the compressor. It reached 20,000 feet (6,100m) of altitude in less than two minutes, and the typical 80,000 feet (24,000m) cruising altitude in another 17 minutes, having used one third of its fuel. 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. Crickmore, Paul F. "Blackbirds in the Cold War". Food was contained in sealed containers similar to toothpaste tubes which delivered food to the crewmember's mouth through the helmet opening. Despite this, however, its shape made it vulnerable to radar detection. After a meeting with the CIA in March 1959, the design was modified to have a 90% reduction in radar cross-section. Lockheed SR-71 (Blackbird) - Military Factory 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). [111] The most common site for the lock-on was the thin stretch of international airspace between land and Gotland that the SR-71s used on their return flights. To start the engines, triethylborane (TEB), which ignites on contact with air, was injected to produce temperatures high enough to ignite the JP-7. This lack of immediate real-time capability was used as one of the justifications to close down the program. 64-17972, flying from New York to London in 1 hour 54 minutes and 56 seconds, for an average speed of 1,806.96 mph. Modifications were made to provide a data-link with "near real-time" transmission of the Advanced Synthetic Aperture Radar's imagery to sites on the ground.[104]. On May 1, 1960, a surface-to-air missile explosion knocked down the U-2 of Gary Powers over Soviet airspace. 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). As space-based surveillance systems became more sophisticated and air defense systems became more effective, the Air Force chose to end the expensive program. Morrison, Bill, SR-71 contributors, Feedback column. [138][139] However, the USAF is officially pursuing the Northrop Grumman RQ-180 UAV to assume the SR-71's strategic ISR role. Cesium-based fuel additives were used to somewhat reduce exhaust plumes' visibility to radar, although exhaust streams remained quite apparent. 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. [26], In 1988, Congress was convinced to allocate $160,000 to keep six SR-71s and a trainer model in flyable storage that could become flightworthy within 60 days. On landing, the canopy temperature was over 572F (300C). The Blackbird was designed to provide reconnaissance in defended airspace while improving aircrew survivability. The limitations of reconnaissance satellites, which take up to 24 hours to arrive in the proper orbit to photograph a particular target, make them slower to respond to demand than reconnaissance planes. In other words, it was a spy plane. As the fastest jet aircraft in the world, the SR-71 has an impressive collection of records and history of service. Johnson decided to counter this criticism by revealing the existence of the YF-12A USAF interceptor, which also served as cover for the still-secret A-12[20] and the USAF reconnaissance model since July 1964. [85], The cockpit could be pressurized to an altitude of 10,000 or 26,000ft (3,000 or 8,000m) during flight. Despite a brief revival of SR-71 flights in the mid-1990s, the program came to a final close in 1998. As the U-2 was called Kellys Angel, or Angel, Lockheeds designs for its successor were designated with an A prefix for Archangel. The CIA gave the contract to Lockheeds A-11, which was modified and secretly re-designated the A-12. A second round of armed JA-37s from ngelholm replaced the first pair and completed the escort to Danish airspace. 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. 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 SR-71 was the world's fastest and highest-flying operational manned aircraft throughout its career. The strategic reconnaissance aircraft could operate at an altitude of . 3,500lb (1,588kg) of mission equipment, Aircraft of comparable role, configuration, and era. "Department of Defense Authorization for Appropriations for Fiscal Year 1994 and The Future Years.". The V8 start carts remained at diversion landing sites not equipped with the pneumatic system. The SR-71 Blackbird is perhaps the most impressive plane ever built. "Lockheed's Blackbirds: A-12, YF-12 and SR-71". [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. Speculation existed regarding a replacement for the SR-71, including a rumored aircraft codenamed Aurora. Air Force and NASA. Lockheed SR-71 Blackbird - The Plane Designed to Leak Secrets We Never Knew About The SR-71 Blackbird - HotCars 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. SR-71 Blackbird - Absolute Altitude (Sustained Flight) - Manned SR-71 Blackbird: One Flight - Four Speed Records. Still-active USAF pilots and Reconnaissance Systems Officers (RSOs) who had worked with the aircraft were asked to volunteer to fly the reactivated planes. Famous Vehicles Of The Air Force And Their Most Ridiculous Features It carried one highly sophisticated, downward-looking film camera, but the plan was to eventually outfit the craft with an infrared camera, side-looking radar, and a gamma spectrometer. These A-12s flew missions over Laos, North Vietnam, and North Korea. The Blackbirds Pratt & Whitney J58 engines were designed to operate continuously in afterburner to facilitate cruise at supersonic speeds. This generated a rapid counter-yawing, often coupled with loud "banging" noises, and a rough ride during which crews' helmets would sometimes strike their cockpit canopies. These same factions also forced expensive sensor upgrades to the SR-71, which did little to increase its mission capabilities, but could be used as justification for complaining about the cost of the program. No. SR-71 Blackbird Sets London-to-LA Speed Record - HistoryNet [N 5][47][48], The air inlets allowed the SR-71 to cruise at over Mach3.2, with the air slowing down to subsonic speed as it entered the engine. The dark color led to the aircraft's nickname "Blackbird". [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. Its initial purpose would have been to conduct post-nuclear strike reconnaissance; that is, looking over the enemys situation after a nuclear exchange. Twelve SR-71s were lost and one pilot died in accidents during the aircraft's service career. Just to put the speed of the SR-71 into . [27] 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 highest altitude recorded on an SR-71 Blackbird is 25,929 meters. 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. The fact is that the real performances are still classified even today. 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. Back when they were building the airplane the United States didn't have the ore supplies an ore called rutile ore. 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. 3. As velocity decreased, so did frictional heat. Locals nicknamed the SR-71 Habu, after a poisonous pit viper found on the neighboring Ryukyu Islands. [23] Production of the SR-71 totaled 32 aircraft with 29 SR-71As, two SR-71Bs, and the single SR-71C.[24]. NASA.gov brings you the latest images, videos and news from America's space agency. This position reflected the spike shock wave repeatedly between the spike center body and the inlet inner cowl sides, and minimized airflow spillage which is the cause of spillage drag. It is the integration of strategic and tactical. Several aircraft have exceeded this altitude in zoom climbs, but not in sustained flight. One widely conventional view, and probably the best-known view, of the reasons for the SR-71's retirement in 1989a view that the Air Force itself offered to the Congresswas that besides being very expensive, the SR-71 had become redundant anyway, among other reconnaissance methods that were ever-evolving. [30] Metallurgical contamination was another problem; at one point, 80% of the delivered titanium for manufacture was rejected on these grounds.[31][32]. Colonel Rich Graham, SR-71 pilot, described the acquisition process: The airplane is 92% titanium inside and out. The SR-71 carried a Fairchild tracking camera and an infrared camera,[80] both of which ran during the entire mission. 61-7956/NASA No. 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. [19], During the 1964 campaign, Republican presidential nominee Barry Goldwater repeatedly criticized President Lyndon B. Johnson and his administration for falling behind the Soviet Union in developing new weapons. They maintained that, in a time of constrained military budgets, designing, building, and testing an aircraft with the same capabilities as the SR-71 would be impossible. (In order to be selected into the SR-71 program in the first place, a pilot or navigator (RSO) had to be a top-quality USAF officer, so continuing career progression for members of this elite group was not surprising.) [7] The SR-71 has several nicknames, including "Blackbird" and "Habu". Former USAF maintainer explains why the iconic SR-71 Blackbird could [3] SR-71 Image Gallery | NASA The shock waves generated slowed the air to subsonic speeds relative to the engine. The USAF may have seen the SR-71 as a bargaining chip to ensure the survival of other priorities. The CIA requested designs from aerospace manufacturers for a new aircraft that would not be as susceptible to attack. For comparison, the best commercial Concorde flight time was 2 hours 52 minutes and the Boeing 747 averages 6 hours 15 minutes. SR-71 Blackbird Speed and Altitude Records The design was designated YF-12A in 1962 and it took its first successful Groom Lake flight in the following year. Lockheed SR-71 Blackbird (Air Vanguard) by Crickmore, Paul F NASA Armstrong Fact Sheet: SR-71 Blackbird | NASA The modified A-12s were re-designated M-21s, and were designed to take off with the D-21 and then launch the drone at speeds high enough to ignite the drones ramjet motor. Rob Vermeland, Lockheed Martin's manager of Advanced Development Program, said in an interview in 2015 that high-tempo operations were not realistic for the SR-71. Only one aircraft even has the distinction of achieving radar lock on the legendary spy plane. When the SR-71 was retired in 1990, one Blackbird was flown from its birthplace at USAF Plant 42 in Palmdale, California, to go on exhibit at what is now the Smithsonian Institution's Steven F. Udvar-Hazy Center in Chantilly, Virginia. [N 1] It was operated by the United States Air Force (USAF) and NASA.[1]. The major supplier of the ore was the USSR. The SR-71 entered service in January 1966. [45], Aerodynamicists discovered that the chines generated powerful vortices and created additional lift, leading to unexpected aerodynamic performance improvements. [100][101] Over the course of its reconnaissance missions during the Vietnam War, the North Vietnamese fired approximately 800 SAMs at SR-71s, none of which managed to score a hit. [33] However, in practice the SR-71 was sometimes more efficient at even faster speedsdepending on the outside air temperatureas measured by pounds of fuel burned per nautical mile traveled. [29] To control costs, Lockheed used a more easily worked titanium alloy which softened at a lower temperature. One plane was almost hit by a missile on 26 August 1981 over the demilitarized zone between North and South Korea but managed to evade and out-fly it. SR-71 Blackbird - Absolute Speed Record - Manned Aircraft [90][40], The first flight of an SR-71 took place on 22 December 1964, at USAF Plant 42 in Palmdale, California, piloted by Bob Gilliland. As the SR-71 had a second cockpit behind the pilot for the RSO, it could not carry the A-12's principal sensor, a single large-focal-length optical camera that sat in the "Q-Bay" behind the A-12's single cockpit. After passing through the turbine, the exhaust, together with the compressor bleed air, entered the afterburner. It has set numerous speed and altitude records including the following in chronological order. The same day another SR-71 set an absolute speed record of 3,529.6 kilometers per hour (2,193.2 miles per hour), approximately Mach 3.3. SR-71 Blackbird spotted breaking the sound barrier at high altitude. [140], National Aeronautics and Space Administration (NASA)[150]. [69] As an aid to the pilot when refueling, the cockpit was fitted with a peripheral vision horizon display. [105] Five flights were attempted but on each occasion no photographs of the flight path were obtained due to low visibility.[106]. Goodall, James and Jay Miller. Years before the Powers incident, the CIA had commissioned a study to determine the characteristics for a reconnaissance aircraft that could not be shot down. 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. The CIA approved a US$96million contract for Skunk Works to build a dozen spy planes, named "A-12", on 11 February 1960. Mach3.2 was the design point for the aircraft, its most efficient speed. [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. No. This portion of the skin was only supported by widely spaced structural ribs. Marshall, Elliot, The Blackbird's Wake, Air and Space, October/November 1990, p. 35.