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77-478: CL-400 or variation , may refer to: Vehicles [ edit ] Lockheed CL-400 Suntan , a proposed U.S. high altitude superfast spyplane of the late 1950s Canadair CL-44 (aka Rolls-Royce 400 PropJet , Canadair 400 , CL-400 ), turboprop airliner Honda CL400 , a 387cc single-cylinder motorcycle Mercedes-Benz CL 400, a luxury sedan, see Mercedes-Benz CL-Class Other uses [ edit ] IBM CL 400,

154-554: A Fairchild tracking camera and an infrared camera , both of which ran during the entire mission. 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. Instead, the SR-71's camera systems could be located either in the fuselage chines or

231-577: 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. The SR-71 featured chines,

308-477: A crew of two in tandem cockpits, and reshaped fuselage chines . Reconnaissance equipment included signals intelligence sensors, a side-looking airborne radar , and a photo camera. The CIA's A-12 was a better photo-reconnaissance platform than the USAF's R-12: since the A-12 flew higher and faster, and with only a pilot, it had room to carry a better camera and more instruments. The A-12 flew covert missions while

385-559: A dozen A-12 spy planes. Three months later, the May 1960 downing of Francis Gary Powers 's U-2 underscored the need for less vulnerable reconnaissance aircraft. The A-12 first flew at Groom Lake ( Area 51 ), Nevada, on 25 April 1962. Thirteen were built, plus five more of two variants: three of the YF-12 interceptor prototype and two of the M-21 drone carrier. The aircraft was to be powered by

462-504: A drag at Blackbird speeds. The aerodynamic features and functioning of the inlet are the subject of a patent, "Supersonic Inlet For Jet Engines" by the inlet designer, David Campbell. When operating as an efficient supersonic compressor (known as started), supersonic diffusion takes place in front of the cowl and internally in a converging passage as far as a terminal shock where the passage area starts increasing and subsonic diffusion takes place. The inlet may also operate very inefficiently if

539-486: A drag parachute to reduce landing roll and brake and tire wear. The second operational aircraft designed around a stealth aircraft shape and materials, following the Lockheed A-12 , the SR-71 had several features designed to reduce its radar signature. The SR-71 had a radar cross-section (RCS) around 110 sq ft (10 m ). Drawing on early studies in radar stealth technology , which indicated that

616-471: A given mission, an aircraft carried several of these frequency/purpose payloads to meet the expected threats. 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. After landing, information from

693-497: A high enough pressure recovery to support the ejector pumping action. Additional air comes from the rear bypass doors and, for low speed operation with negligible inlet ram, from suck-in doors by the compressor case. The nozzle had to operate efficiently over a wide range of pressure ratios from low, with no inlet ram with a stationary aircraft, to 31 times the external pressure at 80,000 ft. A blow-in door ejector nozzle had been invented by Pratt & Whitney engineer Stuart Hamilton in

770-532: A highly secretive program of research and development on high-speed aircraft for long-range reconnaissance. Lockheed 's Skunk Works was the natural partner for this work, having successfully delivered the U-2 and having all the required secrecy and security arrangements to keep the program secret. Lockheed settled on the CL-400 design, which looked like a greatly scaled-up Lockheed F-104 Starfighter . The main change to

847-491: A pair of sharp edges leading aft from either side of the nose along the fuselage. 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. After

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924-515: 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. Special radar-absorbing materials were incorporated into sawtooth-shaped sections of the aircraft's skin. Cesium -based fuel additives were used to somewhat reduce the visibility of exhaust plumes to radar, although exhaust streams remained quite apparent. Johnson later conceded that Soviet radar technology advanced faster than

1001-410: A single unstart was unstarting both inlets to prevent yawing, then restarting them both. After wind tunnel testing and computer modeling by NASA Dryden test center, Lockheed installed an electronic control to detect unstart conditions and perform this reset action without pilot intervention. During troubleshooting of the unstart issue, NASA also discovered the vortices from the nose chines were entering

1078-662: A spot location for higher resolution. ELINT-gathering systems, called the Electro Magnetic Reconnaissance System, built by AIL could be carried in the chine bays to analyze electronic signal fields being passed through, and were programmed to identify items of interest. 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

1155-448: A standard day temperature, and a particular weight, that Mach 3.0 cruise used 38,000 lb per hour of fuel. At 3.15 Mach the fuel flow was 36,000 lb/hr. Flying in colder temperatures (known as temperature deviations from the standard day) would also reduce the fuel used, e.g. with a -10 degC temperature the fuel flow was 35,000 lb/hr. During one mission, SR-71 pilot Brian Shul flew faster than usual to avoid multiple interception attempts. It

1232-531: A variety of stars as the aircraft's changing position brought them into view. The system's digital computer ephemeris contained data on a list of stars used for celestial navigation : the list first included 56 stars and was later expanded to 61. The ANS could supply altitude and position to flight controls and other systems, including the mission data recorder, automatic navigation to preset destination points, automatic pointing and control of cameras and sensors, and optical or SLR sighting of fixed points loaded into

1309-482: Is located, 3) cowl boundary layer bleed 'shock trap' entrance, 4) streamlined bodies known as 'mice' in subsonic flow, 5) forward bypass bleed ports between each of the 'mice', 6) rear bypass ring, 7) louvers on external surface for spike boundary layer overboard, 8) louvers on external surface for front bypass overboard. Venting this bypass overboard could affect the aircraft flying qualities because it produced high drag, 6,000 lb at cruise with 50% door opening, compared to

1386-532: The Pratt & Whitney J58 engine, but J58 development was taking longer than scheduled, so it was initially equipped with the lower-thrust Pratt & Whitney J75 to enable flight testing to begin. 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. The A-12 flew missions over Vietnam and North Korea before its retirement in 1968. The program's cancellation

1463-649: The Space Shuttle . The existence of the CL-400 was not fully disclosed to the public until the 1970s, when Lockheed discussed the possibility of using hydrogen as an alternative fuel for future aircraft. SR-71 The Lockheed SR-71 " Blackbird " is a retired long-range , high-altitude, Mach  3+ strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporation . The SR-71 has several nicknames, including " Blackbird " and " Habu ". The SR-71

1540-404: The 1990s, before their second retirement in 1998. NASA was the final operator of the Blackbird, using it as a research platform, until it was retired again in 1999. During missions, the SR-71 operated at high speeds and altitudes (Mach 3.2 and 85,000 ft; 26,000 m), allowing it to evade or outrace threats. If a surface-to-air missile launch was detected , the standard evasive action

1617-551: The ANS before takeoff. According to Richard Graham, a former SR-71 pilot, the navigation system was good enough to limit drift to 1,000 ft (300 m) off the direction of travel at Mach 3. The SR-71 originally included optical/ infrared imagery systems; side-looking airborne radar (SLAR); electronic intelligence (ELINT) gathering systems; defensive systems for countering missile and airborne fighters; and recorders for SLAR, ELINT, and maintenance data. The SR-71 carried

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1694-453: The CL scripting language variant for OS/400, see Control Language See also [ edit ] Canadair CL-415 , amphibious waterbomber [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to

1771-474: The SR-71 flew overt missions; the latter had USAF markings and pilots carried Geneva Conventions Identification Cards . 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. Johnson decided to counter this criticism by revealing the existence of

1848-511: 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. In 1974, a pair of SR-71 flights set the records for highest sustained flight and quickest flight between London and New York. In 1976, it became the fastest airbreathing manned aircraft , previously held by its predecessor,

1925-433: The U.S.Navy. Only the compressor and turbine aerodynamics were retained. New design requirements for cruise at Mach 3.2 included: The engine was an afterburning turbojet for take-off and transonic flight (bleed bypass closed) and a low bypass augmented turbofan for supersonic acceleration (bleed bypass open). It approximated a ramjet during high speed supersonic cruise (with a pressure loss, compressor to exhaust, of 80% which

2002-577: The YF-12 and the SR-71 was also ordered destroyed. Production of the SR-71 totaled 32 aircraft: 29 SR-71As, two SR-71Bs, and one SR-71C. The SR-71 was designed for flight at over Mach  3 with tandem cockpits for a crew of two: a pilot; and a reconnaissance systems officer who navigated and operated the surveillance systems. The SR-71 was designed with the smallest radar cross-section that Lockheed could achieve, an early attempt at stealth design. Aircraft were painted black. This color radiated heat from

2079-614: The YF-12A USAF interceptor, which also served as cover for the still-secret A-12 and the USAF reconnaissance model since July 1964. USAF Chief of Staff General Curtis LeMay preferred the SR (Strategic Reconnaissance) designation and wanted the RS-71 to be named SR-71. Before the July speech, LeMay lobbied to modify Johnson's speech to read "SR-71" instead of "RS-71". The media transcript given to

2156-573: The advisory panel provisionally selected Convair's FISH design over the A-3 on the basis of RCS, Lockheed adopted chines for its A-4 through A-6 designs. Aerodynamicists discovered that the chines generated powerful vortices and created additional lift , leading to unexpected aerodynamic performance improvements. The angle of incidence of the delta wings could be reduced for greater stability and less drag at high speeds, allowing more weight to be carried, such as fuel. Landing speeds were also reduced, as

2233-415: The aircraft on the ground. Proper alignment was achieved as the airframe heated up, with thermal expansion of several inches. Because of this, and the lack of a fuel-sealing system that could remain leak-free with the extreme temperature cycles during flight, the aircraft leaked JP-7 fuel on the ground prior to takeoff, annoying ground crews. The outer windscreen of the cockpit was made of quartz and

2310-471: The aircraft speed increased. The ability of the sealant to prevent leaks was compromised by the expansion and contraction of the skin with each flight. However, the amount of fuel that leaked, measured as drops per minute on the ground from specific locations, was not enough to make refueling necessary. The SR-71 also required in-flight refueling to replenish fuel during long-duration missions. Supersonic flights generally lasted no more than 90 minutes before

2387-421: The aircraft to yaw violently to one side. SAS , autopilot, and manual control inputs would attempt to regain controlled flight, but often extreme yaw would reduce airflow in the opposite engine and stimulate "sympathetic stalls". 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. One response to

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2464-505: The aircraft. However, the aircraft research was redirected to more conventionally fueled designs and resulted in the successful SR-71 . By advancing the state of the art in LH2 propulsion, and by establishing an industrial infrastructure for high-volume hydrogen production , the groundwork was laid for successful use of liquid hydrogen as a liquid rocket propellant for the Apollo program and

2541-399: The airflow approaching the inlet capture area entered the inlet. At supersonic speeds an intake always adapts to the engine requirements, rather than forcing air into the engine, and the unwanted air flows around the outside of the cowl, causing spillage drag. More than half the air approaching the capture area had to be spilled at low supersonic speeds and the amount reduced as the design speed

2618-555: The centerline. Initially, the TEOCs could not match the resolution of the A-12's larger camera, but rapid improvements in both the camera and film improved this performance. SLAR, built by Goodyear Aerospace , could be carried in the removable nose. In later life, the radar was replaced by Loral's Advanced Synthetic Aperture Radar System (ASARS-1). 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

2695-596: The chines' vortices created turbulent flow over the wings at high angles of attack , making it harder to stall . The chines also acted like leading-edge extensions , which increase the agility of fighters such as the F-5 , F-16 , F/A-18 , MiG-29 , and Su-27 . The addition of chines also allowed the removal of the planned canard foreplanes. The same powerplant was used for the A-12, YF-12 and SR-71. It consists of three main parts, inlet, J58 engine and its nacelle, and ejector nozzle. All three have an important influence on

2772-679: The closely related Lockheed YF-12 . As of 2024 , the Blackbird still holds all three world records. Lockheed's previous reconnaissance aircraft was the relatively slow U-2 , designed for the Central Intelligence Agency (CIA). In late 1957, the CIA approached the defense contractor Lockheed to build an undetectable spy plane. The project, named Archangel, was led by Kelly Johnson , head of Lockheed's Skunk Works unit in Burbank, California. The work on project Archangel began in

2849-438: The cockpit was fitted with a peripheral vision horizon display . 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. If a KC-135Q was not available any tanker with JP-4 or JP-5 could be used in an emergency to avoid losing the aircraft, but with a Mach 1.5 speed limit. On hot days, when approaching

2926-583: The engine and interfering with engine efficiency. NASA developed a computer to control the engine bypass doors which countered this issue and improved efficiency. Beginning in 1980, the analog inlet control system was replaced by a digital system, Digital Automatic Flight and Inlet Control System (DAFICS), which reduced unstart instances. The engine was an extensively re-designed version of the J58-P2, an existing supersonic engine which had run 700 development hours in support of proposals to power various aircraft for

3003-399: The engine. Fuel was automatically diverted, by the fuel derich system, from the combustor to prevent turbine over-temperature. All three parts were linked by the secondary airflow. The inlet needed the boundary layers removed from its spike and cowl surfaces. The one with the higher pressure recovery, the cowl shock-trap bleed, was chosen as secondary air to ventilate and cool the outside of

3080-447: The engine. It was assisted from the inlet by the pumping action of the engine exhaust in the ejector nozzle, cushioning the engine exhaust as it expanded over a wide range of pressure ratios which increased with flight speed. Mach 3.2 in a standard day atmosphere was the design point for the aircraft. However, in practice the SR-71 was more efficient at even faster speeds and colder temperatures. The specific range charts showed for

3157-412: The enormous fuselage to hold the required fuel load. In addition to Lockheed, Pratt and Whitney played a major part. Program successes included the concept design of a Mach 2.5 aircraft capable of flying at 30,000 meters, and successful conversion of an existing turbojet engine to run on liquid hydrogen, as well as 25+ hours of testing on a customized LH2 engine design. Techniques for handling LH2 on

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3234-455: The ground, including making the fuel, transporting and rapid refuelling systems, were all developed as part of the program. Ultimately, budgetary pressures and difficulty achieving sufficient range, plus the fact that an LH2-powered aircraft was considered too dangerous and expensive to maintain, led to the project's cancellation. In addition, the unusual fuel would have meant that existing airbases would have needed extensive facilities to handle

3311-478: The ill-fated AGM-48 Skybolt missile, the latter of which was adapted for the SR-71. Before takeoff, a primary alignment brought the ANS's inertial components to a high degree of accuracy. In flight, the ANS, which sat behind the reconnaissance systems officer's (RSO's), position, tracked stars through a circular quartz glass window on the upper fuselage. Its "blue light" source star tracker , which could see stars during both day and night, would continuously track

3388-426: The inlet cowl boundary layer and rear bypass from immediately in front of the compressor. It used external flow on the nacelle through the tertiary blow-in doors until ram closed them at Mach 1.5. Only secondary air was used at higher speeds with the blow-in doors closed. At low flight speeds the engine exhaust pressure at the primary nozzle exit was greater than ambient so tended to over-expand to lower than ambient in

3465-496: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=CL-400&oldid=1029779225 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Lockheed CL-400 Suntan Starting in 1956, the United States Air Force funded

3542-429: The introduction of the bleed bypass cycle. These two authors show the disparity between inlet and engine for the Blackbird in terms of airflow and it is further explained in more general terms by Oates. Engine operation was adversely affected when operating behind an unstarted inlet. In this condition the inlet behaved like a subsonic inlet design (known as a pitot type) at high supersonic speeds, with very low airflow to

3619-443: The late 1950s and described in his patent "Variable Area Exhaust Nozzle". In this description the nozzle is an integral part of the engine (as it was in the contemporary Mach 3 General Electric YJ93. For the Blackbird powerplant the nozzle was more efficient structurally (lighter) by incorporating it as part of the airframe because it carried fin and wing loads through the ejector shroud. The nozzle used secondary air from two sources,

3696-538: The later stages of its testing, the B-70 was proposed for a reconnaissance/strike role, with an "RS-70" designation. When the A-12's performance potential was clearly found to be much greater, the USAF ordered a variant of the A-12 in December 1962, which was originally named R-12 by Lockheed. This USAF version was longer and heavier than the original A-12 because it had a longer fuselage to hold more fuel. The R-12 also had

3773-420: The layout was the twin engines, mounted on the wing tips. This was done to ensure that the liquid hydrogen, which was stored in the fuselage, would have to pass through the aircraft's hot wings (up to 436 Kelvin) to reach the engines; a vacuum sealed, insulated line was provided to do this. LH2 was selected due to its predictable burning characteristics and the fuel's light weight, although the low density required

3850-487: The manufacture of other aircraft. 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. Metallurgical contamination was another problem; at one point, 80% of the delivered titanium for manufacture was rejected on these grounds. The high temperatures generated in flight required special design and operating techniques. Major sections of

3927-474: The maximum fuel load of 80,285 lb (36,415 kg), the left engine had to be run with minimum afterburner to maintain probe contact. Nortronics, Northrop Corporation 's electronics development division, had developed an astro-inertial guidance system (ANS), which could correct inertial navigation system errors with celestial observations , for the SM-62 Snark missile, and a separate system for

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4004-413: The overall installed performance of the propulsion system. "Typical for any supersonic powerplant the engine cannot be considered separately from the rest of the powerplant. Rather, it may be regarded as the heat pump in the over-all system of inlet, engine, and nozzle. The net thrust available to propel the aircraft may be to a large extent controlled by the performance of the inlet and nozzle rather than by

4081-587: The physical potentialities of the engine alone." This is illustrated for the Blackbird by the thrust contributions from each component at M3+ with maximum afterburner: inlet 54%, engine 17.6%, ejector nozzle 28.4%. When stationary and at low speeds the inlet caused a loss in engine thrust. This was due to the flow restriction through the inlet when stationary. Thrust was recovered with ram pressure as flight speed increased (uninstalled thrust 34,000 lb, installed at zero airspeed 25,500 lb rising through 30,000 lb at 210 knots, unstick speed). At supersonic speeds not all

4158-508: The pilot had to find a tanker. Specialized KC-135Q tankers were required to refuel the SR-71. The KC-135Q had a modified high-speed boom, which would allow refueling of the Blackbird at near the tanker's maximum airspeed. 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. As an aid to the pilot when refueling,

4235-497: The pioneer "stealth" Lockheed A-12 , with its reduced radar cross section , but the SR-71 was longer and heavier, to allow for more fuel, and a crew of two in tandem cockpits. After the SR-71's existence was revealed to the public in July 1964, it entered service in the United States Air Force (USAF) in January 1966. In 1989, the USAF retired the SR-71, largely for political reasons, although several were briefly reactivated during

4312-547: 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. To conceal the A-12's existence, Johnson referred only to the A-11, while revealing the existence of a high-speed, high-altitude reconnaissance aircraft. In 1968, Secretary of Defense Robert McNamara canceled the F-12 interceptor program. The specialized tooling used to manufacture both

4389-499: The removable nose/chine section. 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. A closer view of the target area was given by the HYCON Technical Objective Camera (TEOC), which could be directed up to 45° left or right of

4466-506: The second quarter of 1958, with aim of flying higher and faster than the U-2. Of 11 successive designs drafted in a span of 10 months, "A-10" was the front-runner, although its shape made it vulnerable to radar detection. After a meeting with the CIA in March 1959, the design was modified to reduce its radar cross-section by 90%. On 11 February 1960, the CIA approved a US$ 96 million (~$ 758 million in 2023) contract for Skunk Works to build

4543-580: The shroud causing impingement shocks. Secondary and blow-in door air surrounding the exhaust cushioned it preventing over-expansion. Inlet ram pressure increased with flight speed and the higher pressure in the exhaust system closed, first the blow-in doors and then started to open the nozzle flaps until they were fully open at M2.4. The final nozzle area did not increase with further increase in flight speed (for complete expansion to ambient and greater internal thrust) because its external diameter, greater than nacelle diameter would cause too much drag. JP-7 fuel

4620-484: The skin of the inboard wings were corrugated, not smooth. 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. But high 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. Fuselage panels were manufactured to fit only loosely with

4697-422: The stealth technology employed against it. 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 invulnerable at the time. 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

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4774-525: The surface more effectively than the bare metal, reducing the temperature of the skin and thermal stresses on the airframe. The appearance of the painted aircraft gave it the nickname "Blackbird". Titanium was used for 85% of the structure, with much of the rest being polymer composite materials . To control costs, Lockheed used a more easily worked titanium alloy, which softened at a lower temperature. |group=N}} The challenges posed led Lockheed to develop new fabrication methods, which have since been used in

4851-676: The terminal shock is not held in position by a control system. In this instance, if the shock moves forward of the minimum area (throat) it will be in an unstable position and shoots forward in an instant to a stable position outside the cowl (known as unstarted). The features of the inlet and what they do are also explained in the "A-12 Utility Flight Manual" and in a presentation by Lockheed Technical Fellow Emeritus Tom Anderson All features are visible in varying degrees in Figures 1, 4 and 5. They are 1) centerbody or spike in fully forward position, 2) spike boundary layer bleed slots where normal shock

4928-539: 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

5005-455: The total aircraft drag of 14,000 lb. In the early years of operation, the analog computers would not always keep up with rapidly changing inputs from the nose boom. If the duct back pressure became too great and the spike was incorrectly positioned, the shock wave would suddenly blow out the front of the inlet, causing an "inlet unstart ". During unstarts, afterburner extinctions were common. The remaining engine's asymmetrical thrust would cause

5082-404: The typical 80,000 feet (24,000 m) cruising altitude in another 17 minutes, having used one third of its fuel. It is a common misconception that the planes refueled shortly after takeoff because the fuel tanks, which formed the outer skin of the aircraft, leaked on the ground. It was not possible to prevent leaks when the aircraft skin was cold and the tanks only sealed when the skin warmed as

5159-425: Was fused ultrasonically to the titanium frame. The temperature of the exterior of the windscreen reached 600 °F (316 °C) during a mission. The Blackbird's tires, manufactured by B.F. Goodrich , contained aluminum and were inflated with nitrogen. They cost $ 2,300 each and generally required replacing within 20 missions. The Blackbird landed at more than 170 knots (200 mph; 310 km/h) and deployed

5236-532: Was announced on 28 December 1966, due both to budget concerns and because of the forthcoming SR-71, a derivative of the A-12. 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 . 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. During

5313-428: Was approached because the inlet airflow had been designed to match the engine demand at that speed and the chosen design point ambient temperature. At this speed the spike shock touched the cowl lip and there was minimal spillage (with its attendant drag) as shown by Campbell. The inlet and engine matching was also shown by Brown, who emphasized the benefit of increased engine airflow at higher Mach numbers that came with

5390-409: Was developed as a black project reconnaissance aircraft during the 1960s by Lockheed's Skunk Works division, initially as a bomber variant of the Lockheed A-12 , requested by Curtis LeMay , before the program focused solely on reconnaissance. 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

5467-525: Was discovered after the flight that this had reduced the fuel consumption. It is possible to match the powerplant for optimum performance at only one ambient temperature because the airflows for a supersonic inlet and engine vary differently with ambient temperature. For an inlet, the airflow varies inversely with the square root of the temperature, and for the engine, it varies with the direct inverse. The inlet needed internal supersonic diffusion since external compression used on slower aircraft caused too high

5544-419: Was enabled with air-cooled 1st stage turbine vane and blades. Continuous operation of maximum afterburning was enabled by passing relatively cool air from the compressor along the inner surface of the duct and nozzle. Ceramic thermal barrier coatings were also used. The secondary airflow through the nacelle comes from the cowl boundary layer bleed system which is oversized (flows more than boundary layer) to give

5621-514: Was not possible due to the limited capacity of the cooling system, so the chemical ignition system was used. On a typical mission, the SR-71 took off with 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. Within 20 seconds, the aircraft traveled 4,500 feet (1,400 m), reached 240 miles per hour (390 km/h), and lifted off. It reached 20,000 feet (6,100 m) of altitude in less than two minutes, and

5698-457: Was to 1) incorporate six air-bleed tubes, prominent on the outside of the engine, to transfer 20% of the compressor air to the afterburner, and 2) to modify the inlet guide vanes with a 2-position, trailing edge flap. The compressor bleed enabled the compressor to operate more efficiently and with the resulting increase in engine airflow matched the inlet design flow with an installed thrust increase of 47%. A continuous turbine temperature of 2,000F

5775-409: Was to accelerate and outpace the missile. Equipment for the plane's aerial reconnaissance missions included signals-intelligence sensors, side-looking airborne radar , and a camera. On average, each SR-71 could fly once per week due to the time required to prepare it for the next mission. A total of 32 aircraft were built; 12 were lost in accidents, none to enemy action. Since its retirement,

5852-492: Was typical of a ramjet). It was a low bypass turbofan for subsonic loiter (bleed bypass open). Analysis of the J58-P2 supersonic performance showed the high compressor inlet temperature would have caused stalling, choking and blade breakages in the compressor as a result of operating at low corrected speeds on the compressor map. These problems were resolved by Pratt & Whitney engineer Robert Abernethy and are explained in his patent, "Recover Bleed Air Turbojet". His solution

5929-467: Was used. It was difficult to ignite. To start the engines, triethylborane (TEB), which ignites on contact with air , was injected to produce temperatures high enough to ignite the JP-7. The TEB produced a characteristic green flame, which could often be seen during engine ignition. The fuel was used as a heat sink for the rest of the aircraft to cool the pilot and the electronics. An electric starting system

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