Misplaced Pages

#216783

121-480: 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 was developed as a black project reconnaissance aircraft during the 1960s by Lockheed's Skunk Works division, initially as

242-529: A η j {\displaystyle P_{br}={\frac {P_{a}}{\eta _{j}}}} The corresponding fuel weight flow rates can be computed now: F = c p P b r {\displaystyle F=c_{p}P_{br}} Thrust power is the speed multiplied by the drag, is obtained from the lift-to-drag ratio : P a = V C D C L W g ; {\displaystyle P_{a}=V{\frac {C_{D}}{C_{L}}}Wg;} here Wg

363-785: A = 7 5 R s T {\textstyle a={\sqrt {{\frac {7}{5}}R_{s}T}}} ; here R s {\displaystyle R_{s}} is the specific heat constant of air 287.16 J/kg K (based on aviation standards) and γ = 7 / 5 = 1.4 {\displaystyle \gamma =7/5=1.4} (derived from γ = c p c v {\textstyle \gamma ={\frac {c_{p}}{c_{v}}}} and c p = c v + R s {\displaystyle c_{p}=c_{v}+R_{s}} ). c p {\displaystyle c_{p}} and c v {\displaystyle c_{v}} are

484-553: 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

605-488: 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 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

726-473: 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 the SR-71 flew overt missions; the latter had USAF markings and pilots carried Geneva Conventions Identification Cards . During

847-532: A thrust specific fuel consumption , so that rate of fuel flow is proportional to drag , rather than power. F = c T T = c T C D C L W {\displaystyle F=c_{T}T=c_{T}{\frac {C_{D}}{C_{L}}}W} Using the lift equation, 1 2 ρ V 2 S C L = W {\displaystyle {\frac {1}{2}}\rho V^{2}SC_{L}=W} where ρ {\displaystyle \rho }

968-572: 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,

1089-521: 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, 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,

1210-644: 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 the 1990s, before their second retirement in 1998. NASA was the final operator of the Blackbird, using it as

1331-409: 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 the surface more effectively than the bare metal, reducing the temperature of the skin and thermal stresses on

SECTION 10

#1732772362217

1452-503: 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

1573-419: 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

1694-470: 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

1815-497: 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

1936-601: A joint USAF/NASA investigation of supersonic cruise technology, and then flown to the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio on 17 November 1979. A fourth YF-12 aircraft, the "YF-12C", was actually the second SR-71A (AF Ser. No. 61–7951). This SR-71A was re-designated as a YF-12C and given the fictitious Air Force Serial Number 60-6937 from an A-12 to maintain SR-71 secrecy. The aircraft

2057-424: A landing mishap on 14 August 1966; its rear half was salvaged and combined with the front half of a Lockheed static test airframe to create the only SR-71C . YF-12A, AF Ser. No. 60-6936 was lost on 24 June 1971 due to an in-flight fire caused by a failed fuel line; both pilots ejected safely just north of Edwards AFB. YF-12A, AF Ser. No. 60-6935 is the only surviving YF-12A; it was recalled from storage in 1969 for

2178-639: A lift-to-drag ratio of 18:1, and a structural efficiency of 50%, the cruise range would be The range equation may be further extended to consider operational factors by including an operational efficiency ("ops" for flight operations) R = Z f η eng η aero η struc η ops {\displaystyle R=Z_{f}\eta _{\text{eng}}\eta _{\text{aero}}\eta _{\text{struc}}\eta _{\text{ops}}} The operational efficiency η o p s {\displaystyle \eta _{ops}} may be expressed as

2299-510: A number of airplane weights from the equilibrium condition P a = P r {\displaystyle P_{a}=P_{r}} is noted . To each flight velocity, there corresponds a particular value of propulsive efficiency η j {\displaystyle \eta _{j}} and specific fuel consumption c p {\displaystyle c_{p}} . The successive engine powers can be found: P b r = P

2420-407: 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, 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

2541-490: 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

SECTION 20

#1732772362217

2662-469: 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 was to accelerate and outpace the missile. Equipment for the plane's aerial reconnaissance missions included signals-intelligence sensors, side-looking airborne radar , and

2783-515: 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

2904-407: 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

3025-602: 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 a dozen A-12 spy planes. Three months later, the May 1960 downing of Francis Gary Powers 's U-2 underscored

3146-615: A specific range and fuel weight flow rate can be related to the characteristics of the airplane and propulsion system; if these are constant: R = η j g c p C L C D ln ⁡ W 1 W 2 = V ( L / D ) I s p L n ( W i / W f ) {\displaystyle R={\frac {\eta _{j}}{gc_{p}}}{\frac {C_{L}}{C_{D}}}\ln {\frac {W_{1}}{W_{2}}}=V(L/D)IspLn(Wi/Wf)} An electric aircraft with battery power only will have

3267-602: 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

3388-447: 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

3509-535: A success and ordered 96 aircraft and had an initial budget of $ 90 million to further testing, but this was withheld by Secretary of Defense McNamara, who on 23 November 1967 put it towards the much less successful F-106X program that nearly failed. The successful AIM-47 Falcon missile was increased in size and performance and became the AIM-54 Phoenix missile for the F-14 Tomcat . The AN/ASG 18 radar

3630-530: 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

3751-557: Is d W d R = d W d t d R d t = − F V , {\displaystyle {\frac {dW}{dR}}={\frac {\frac {dW}{dt}}{\frac {dR}{dt}}}=-{\frac {F}{V}},} where V {\displaystyle V} is the speed), so that d R d t = − V F d W d t {\displaystyle {\frac {dR}{dt}}=-{\frac {V}{F}}{\frac {dW}{dt}}} It follows that

Lockheed SR-71 Blackbird - Misplaced Pages Continue

3872-1235: Is a height that a quantity of fuel could lift itself in the Earth's gravity field (assumed constant) by converting its chemical energy into potential energy. Z f {\displaystyle Z_{f}} for kerosene jet fuel is 2,376 nautical miles (4,400 km) or about 69% of the Earth's radius . There are two useful alternative ways to express the structural efficiency η struc = ln ⁡ W ^ 1 W ^ 2 = ln ⁡ ( 1 + W fuel W ^ 2 ) = − ln ⁡ ( 1 − W fuel W ^ 1 ) {\displaystyle \eta _{\text{struc}}=\ln {\frac {{\widehat {W}}_{1}}{{\widehat {W}}_{2}}}=\ln \left(1+{\frac {{W}_{\text{fuel}}}{{\widehat {W}}_{2}}}\right)=-\ln \left(1-{\frac {{W}_{\text{fuel}}}{{\widehat {W}}_{1}}}\right)} As an example, with an overall engine efficiency of 40%,

3993-526: Is again mass. When cruising at a fixed height, a fixed angle of attack and a constant specific fuel consumption, the range becomes: R = 2 c T C L C D 2 2 g ρ S ( W 1 − W 2 ) {\displaystyle R={\frac {2}{c_{T}}}{\sqrt {{\frac {C_{L}}{C_{D}^{2}}}{\frac {2}{g\rho S}}}}\left({\sqrt {W_{1}}}-{\sqrt {W_{2}}}\right)} where

4114-429: Is assumed that the thrust specific fuel consumption is constant as the aircraft weight decreases. This is generally not a good approximation because a significant portion (e.g. 5% to 10%) of the fuel flow does not produce thrust and is instead required for engine "accessories" such as hydraulic pumps , electrical generators , and bleed air powered cabin pressurization systems. This can be accounted for by extending

4235-404: Is assumed. The relationship D = C D C L W {\displaystyle D={\frac {C_{D}}{C_{L}}}W} is used. The thrust can now be written as: T = D = C D C L W ; {\displaystyle T=D={\frac {C_{D}}{C_{L}}}W;} here W is a force in newtons Jet engines are characterized by

4356-546: Is generally recommended at a slightly higher airspeed. Most long-range cruise operations are conducted at the flight condition that provides 99 percent of the absolute maximum specific range. The advantage of such operation is that one percent of the range is traded for three to five percent higher cruise speed. Lockheed YF-12 The Lockheed YF-12 is an American Mach  3+ capable, high-altitude interceptor prototype , developed and manufactured by American aerospace company Lockheed Corporation . The interceptor

4477-482: 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

4598-451: Is the air density , and S the wing area , the specific range is found equal to: V F = 1 c T C L C D 2 2 ρ S W {\displaystyle {\frac {V}{F}}={\frac {1}{c_{T}}}{\sqrt {{\frac {C_{L}}{C_{D}^{2}}}{\frac {2}{\rho SW}}}}} Inserting this into ( 1 ) and assuming only W {\displaystyle W}

4719-628: Is the energy per mass of the battery (e.g. 150-200 Wh/kg for Li-ion batteries), η total {\displaystyle \eta _{\text{total}}} the total efficiency (typically 0.7-0.8 for batteries, motor, gearbox and propeller), L / D {\displaystyle L/D} lift over drag (typically around 18), and the weight ratio W battery / W total {\displaystyle {W_{\text{battery}}}/{W_{\text{total}}}} typically around 0.3. The range of jet aircraft can be derived likewise. Now, quasi-steady level flight

4840-412: Is the speed, and F {\displaystyle F} is the fuel consumption rate, is called the specific range (= range per unit mass of fuel; S.I. units: m/kg). The specific range can now be determined as though the airplane is in quasi-steady-state flight. Here, a difference between jet and propeller-driven aircraft has to be noticed. With propeller-driven propulsion, the level flight speed at

4961-607: Is the weight (force in newtons, if W is the mass in kilograms); g is standard gravity (its exact value varies, but it averages 9.81 m/s ). The range integral, assuming flight at a constant lift to drag ratio, becomes R = η j g c p C L C D ∫ W 2 W 1 d W W {\displaystyle R={\frac {\eta _{j}}{gc_{p}}}{\frac {C_{L}}{C_{D}}}\int _{W_{2}}^{W_{1}}{\frac {dW}{W}}} To obtain an analytic expression for range,

Lockheed SR-71 Blackbird - Misplaced Pages Continue

5082-503: Is the zero-fuel mass and W f {\displaystyle W_{f}} the mass of the fuel, the fuel consumption rate per unit time flow F {\displaystyle F} is equal to − d W f d t = − d W d t . {\displaystyle -{\frac {dW_{f}}{dt}}=-{\frac {dW}{dt}}.} The rate of change of aircraft mass with distance R {\displaystyle R}

5203-490: Is varying, the range (in kilometers) becomes: R = 1 c T C L C D 2 2 g ρ S ∫ W 2 W 1 1 W d W ; {\displaystyle R={\frac {1}{c_{T}}}{\sqrt {{\frac {C_{L}}{C_{D}^{2}}}{\frac {2}{g\rho S}}}}\int _{W_{2}}^{W_{1}}{\frac {1}{\sqrt {W}}}dW;} here W {\displaystyle W}

5324-588: 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 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

5445-590: The AIM-47 missiles were completed, and a seventh failed due to a gyro failure on one of the missiles. The last one was launched from the YF-12 at Mach 3.2 at an altitude of 74,000 feet (23,000 m) to a JQB-47E target drone 500 feet (150 m) off the ground. The missile did not have a warhead but still managed to hit the B-47 directly and take a 4 feet (120 cm) section off its tail. The Air Force considered it

5566-599: 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 the second quarter of 1958, with aim of flying higher and faster than the U-2. Of 11 successive designs drafted in

5687-570: The Vietnam War and other military priorities. It set and held speed and altitude world records of over 2,000 miles per hour (3,200 km/h) and over 80,000 feet (24,000 m) (later surpassed by the closely related SR-71 Blackbird ), and is the world's largest, heaviest and fastest crewed interceptor. Following its retirement by the USAF, it served as a research aircraft for NASA for a time, which used it to develop several significant improvements in control for future supersonic aircraft. In

5808-517: The great-circle distance divided by the actual route distance η route = D GC D actual {\displaystyle \eta _{\text{route}}={\frac {D_{\text{GC}}}{D_{\text{actual}}}}} Off-nominal temperatures may be accounted for with a temperature efficiency factor η temp {\displaystyle \eta _{\text{temp}}} (e.g. 99% at 10 deg C above International Standard Atmosphere (ISA) temperature). All of

5929-728: The thrust specific fuel consumption has been adjusted down and the virtual aircraft weight has been adjusted up to maintain the proper fuel flow while making the adjusted thrust specific fuel consumption truly constant (not a function of virtual weight). Then, the modified Breguet range equation becomes R = a M g c ^ T C L C D ln ⁡ W ^ 1 W ^ 2 {\displaystyle R={\frac {aM}{g{\widehat {c}}_{T}}}{\frac {C_{L}}{C_{D}}}\ln {\frac {{\widehat {W}}_{1}}{{\widehat {W}}_{2}}}} The above equation combines

6050-442: The 2.5-year program was US$ 14 million (~$ 37.4 million in 2023). The YF-12 and SR-71 originally suffered from severe control issues that affected both the engines and the physical control of the aircraft. Wind testing at NASA Dryden and YF-12 research flights developed computer systems that nearly completely solved the performance issues. Testing revealed vortices from the nose chines interfering with intake air, which led to

6171-556: 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 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

SECTION 50

#1732772362217

6292-479: The A-12 reconnaissance aircraft for the U.S. Central Intelligence Agency (CIA) under the Oxcart program. Kelly Johnson , the head of Skunk Works, proposed to build a version of the A-12 named AF-12 by the company; the USAF ordered three AF-12s in mid-1960. The AF-12s took the seventh through ninth slots on the A-12 assembly line; these were designated as YF-12A interceptors. The main changes involved modifying

6413-507: The A-12's nose by cutting back the chines to accommodate the huge Hughes AN/ASG-18 fire-control radar originally developed for the XF-108 with two infrared search and track sensors located in the chine leading edge, and the addition of the second cockpit for a crew member to operate the fire control radar for the air-to-air missile system. The modifications changed the aircraft's aerodynamics enough to require ventral fins to be mounted under

6534-494: 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 a crew of two in tandem cockpits, and reshaped fuselage chines . Reconnaissance equipment included signals intelligence sensors,

6655-544: 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

6776-536: The French aviation pioneer, Louis Charles Breguet . It is possible to improve the accuracy of the Breguet range equation by recognizing the limitations of the conventionally used relationships for fuel flow: F = c T T = c T C D C L W {\displaystyle F=c_{T}T=c_{T}{\frac {C_{D}}{C_{L}}}W} In the Breguet range equation, it

6897-668: The SLAR, ELINT gathering systems, and the maintenance data recorder were subjected to postflight ground analysis. In the later years of its operational life, a datalink system could send ASARS-1 and ELINT data from about 2,000 nmi (3,700 km) of track coverage to a suitably equipped ground station. Range (aeronautics) Some aircraft can gain energy while airborne through the environment (e.g. collecting solar energy or through rising air currents from mechanical or thermal lifting) or from in-flight refueling. These aircraft could theoretically have an infinite range. Ferry range means

7018-525: 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 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

7139-433: 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

7260-571: 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

7381-412: 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

SECTION 60

#1732772362217

7502-469: 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

7623-420: 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

7744-399: 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

7865-411: 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

7986-686: The assumed fuel flow formula in a simple way where an "adjusted" virtual aircraft gross weight W ^ {\displaystyle {\widehat {W}}} is defined by adding a constant additional "accessory" weight W acc {\displaystyle W_{\text{acc}}} . W ^ = W + W acc {\displaystyle {\widehat {W}}=W+W_{\text{acc}}} F = c ^ T C D C L W ^ {\displaystyle F={\widehat {c}}_{T}{\frac {C_{D}}{C_{L}}}{\widehat {W}}} Here,

8107-552: 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

8228-593: 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

8349-436: 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

8470-437: The compressibility on the aerodynamic characteristics of the airplane are neglected as the flight speed reduces during the flight. For jet aircraft operating in the stratosphere (altitude approximately between 11 and 20 km), the speed of sound is approximately constant, hence flying at a fixed angle of attack and constant Mach number requires the aircraft to climb (as weight decreases due to fuel burn), without changing

8591-432: The control of supersonic aircraft in flight. At such high speeds even minor changes in direction caused the aircraft to change position by thousands of feet, and often had severe temperature and pressure changes. CAPCS reduced these deviations by a factor of 10. The overall improvements increased range of the SR-71 by 7 percent. Of the three YF-12As, AF Ser. No. 60-6934 was damaged beyond repair by fire at Edwards AFB during

8712-484: The development of a computer control system to open the forward bypass doors. A computer system to reduce unstarts was also developed. They also developed a flight engineering computer program called Central Airborne Performance Analyzer (CAPA) that relayed engine data to the pilots and informed them of any faults or issues with performance and indicated the severity of malfunctions. Another system called Cooperative Airframe-Propulsion Control System (CAPCS) greatly improved

8833-698: The energy characteristics of the fuel with the efficiency of the jet engine. It is often useful to separate these terms. Doing so completes the nondimensionalization of the range equation into fundamental design disciplines of aeronautics . R = Z f a M Z f g c ^ T C L C D ln ⁡ W ^ 1 W ^ 2 {\displaystyle R=Z_{f}{\frac {aM}{Z_{f}g{\widehat {c}}_{T}}}{\frac {C_{L}}{C_{D}}}\ln {\frac {{\widehat {W}}_{1}}{{\widehat {W}}_{2}}}} where giving

8954-581: 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

9075-412: 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 the engine. It

9196-426: The final form of the theoretical range equation (not including operational factors such as wind and routing) R = Z f η eng η aero η struc {\displaystyle R=Z_{f}\eta _{\text{eng}}\eta _{\text{aero}}\eta _{\text{struc}}} The geopotential energy height of the fuel is an intensive property . A physical interpretation

9317-624: 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 the later stages of its testing, the B-70 was proposed for a reconnaissance/strike role, with an "RS-70" designation. When

9438-634: The funding for three consecutive years due to Vietnam War costs. Updated intelligence placed a lower priority on defense of the continental US, so the F-12B was deemed no longer needed. Then in January 1968, the F-12B program was officially ended. During flight tests the YF-12As set a speed record of 2,070.101 miles per hour (3,331.505 km/h) and altitude record of 80,257.86 feet (24,462.60 m), both on 1 May 1965, and demonstrated promising results with its unique weapon system. Six successful firings of

9559-400: The fuselage and engine nacelles to maintain stability. Three of the four bays previously used to house the A-12's reconnaissance equipment were converted to carry Hughes AIM-47 Falcon (GAR-9) missiles. One bay was used for fire control equipment. The first YF-12A flew on 7 August 1963. President Lyndon B. Johnson announced the existence of the aircraft on 24 February 1964. The YF-12A

9680-475: 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

9801-426: 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

9922-428: 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

10043-440: 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,

10164-753: The late 1950s, the United States Air Force (USAF) sought a replacement for its F-106 Delta Dart interceptor. As part of the Long Range Interceptor Experimental (LRI-X) program, the North American XF-108 Rapier , an interceptor with Mach 3 speed, was selected. However, the F-108 program was canceled by the Department of Defense in September 1959. During this time, Lockheed's Skunk Works was developing

10285-433: 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 was announced on 28 December 1966, due both to budget concerns and because of

10406-484: 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

10527-632: The maximum flight time is variable, limited by available daylight hours, aircraft design (performance), weather conditions, aircraft potential energy, and pilot endurance. Therefore, the range equation can only be calculated exactly for powered aircraft. It will be derived for both propeller and jet aircraft. If the total mass W {\displaystyle W} of the aircraft at a particular time t {\displaystyle t} is: W = W 0 + W f , {\displaystyle W=W_{0}+W_{f},} where W 0 {\displaystyle W_{0}}

10648-472: 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

10769-480: The maximum range that an aircraft engaged in ferry flying can achieve. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to the transport of aircraft without any passengers or cargo. Combat radius is a related measure based on the maximum distance a warplane can travel from its base of operations, accomplish some objective, and return to its original airfield with minimal reserves. For most unpowered aircraft,

10890-573: 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 the Pratt & Whitney J58 engine, but J58 development was taking longer than scheduled, so it was initially equipped with

11011-437: The operational efficiency factors may be collected into a single term η ops = η route η wind η temp ⋯ {\displaystyle \eta _{\text{ops}}=\eta _{\text{route}}\eta _{\text{wind}}\eta _{\text{temp}}\cdots } While the peak value of a specific range would provide maximum range operation, long-range cruise operation

11132-413: 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

11253-584: 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

11374-506: 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,

11495-587: The product of individual operational efficiency terms. For example, average wind may be accounted for using the relationship between average GroundSpeed (GS), True AirSpeed (TAS, assumed constant), and average HeadWind (HW) component. η wind = T A S − H W avg T A S = G S avg T A S {\displaystyle \eta _{\text{wind}}={\frac {TAS-HW_{\text{avg}}}{TAS}}={\frac {GS_{\text{avg}}}{TAS}}} Routing efficiency may be defined as

11616-528: The range is obtained from the definite integral below, with t 1 {\displaystyle t_{1}} and t 2 {\displaystyle t_{2}} the start and finish times respectively and W 1 {\displaystyle W_{1}} and W 2 {\displaystyle W_{2}} the initial and final aircraft masses The term V F {\textstyle {\frac {V}{F}}} , where V {\displaystyle V}

11737-499: 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

11858-612: The same mass at takeoff and landing. The logarithmic term with weight ratios is replaced by the direct ratio between W battery / W total {\displaystyle W_{\text{battery}}/W_{\text{total}}} R = E ∗ 1 g η total L D W battery W total {\displaystyle R=E^{*}{\frac {1}{g}}\eta _{\text{total}}{\frac {L}{D}}{\frac {W_{\text{battery}}}{W_{\text{total}}}}} where E ∗ {\displaystyle E^{*}}

11979-579: 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

12100-484: 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

12221-474: The specific heat capacities of air at constant pressure and constant volume respectively. Or R = a M g c T C L C D ln ⁡ W 1 W 2 {\textstyle R={\frac {aM}{gc_{T}}}{\frac {C_{L}}{C_{D}}}\ln {\frac {W_{1}}{W_{2}}}} , also known as the Breguet range equation after

12342-421: 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

12463-674: 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

12584-625: The test program included objectives aimed at answering some questions about implementation of the B-1 . Air Force objectives included exploration of its use in a tactical environment, and how airborne early warning and control (AWACS) would control supersonic aircraft. The Air Force portion was budgeted at US$ 4 million. The NASA tests would answer questions such as how engine inlet performance affected airframe and propulsion interaction, boundary layer noise, heat transfer under high Mach conditions, and altitude hold at supersonic speeds. The NASA budget for

12705-539: 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

12826-454: 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

12947-403: 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

13068-629: The value of the local speed of sound. In this case: V = a M {\displaystyle V=aM} where M {\displaystyle M} is the cruise Mach number and a {\displaystyle a} the speed of sound . W is the weight. The range equation reduces to: R = a M g c T C L C D ∫ W 2 W 1 d W W {\displaystyle R={\frac {aM}{gc_{T}}}{\frac {C_{L}}{C_{D}}}\int _{W_{2}}^{W_{1}}{\frac {dW}{W}}} where

13189-423: 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

13310-690: Was announced in part to continue hiding the A-12, its still-secret ancestor; any sightings of CIA/Air Force A-12s based at Area 51 in Nevada could be attributed to the well-publicized Air Force YF-12As based at Edwards Air Force Base in California. The first public showing of the aircraft was on 30 September 1964 at Edwards. On 14 May 1965, the Air Force placed a production order for 93 F-12Bs for its Air Defense Command (ADC). However, Secretary of Defense Robert McNamara would not release

13431-426: 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

13552-431: 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

13673-622: Was developed during the late 1950s and early 1960s as a potential replacement for the F-106 Delta Dart interceptor for the United States Air Force (USAF). The YF-12 was a twin-seat version of the then-secret single-seat Lockheed A-12 reconnaissance aircraft operated by the Central Intelligence Agency (CIA); unlike the A-12, it was furnished with the Hughes AN/ASG-18 fire-control radar and could be armed with AIM-47 Falcon (GAR-9) air-to-air missiles . Its maiden flight

13794-523: 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

13915-419: 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

14036-512: 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

14157-479: Was on 7 August 1963. Its existence was publicly revealed by President Lyndon B. Johnson on 24 February 1964; this move was to provide plausible deniability for the CIA-operated A-12 fleet, which closely resembled the prototype YF-12. During the 1960s, the YF-12 underwent flight evaluations by the USAF, but funding to put it into operational use was not forthcoming partly due to the pressing demands of

14278-455: 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

14399-488: 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

14520-571: Was upgraded to become the AN/AWG-9 and APG-71, which added the ability to track multiple targets. One of the Air Force test pilots, Jim Irwin , would go on to become a NASA astronaut and walk on the Moon . The program was abandoned following the cancellation of the production F-12B, but the YF-12s continued flying for many years with the USAF and with NASA as research aircraft. The initial phase of

14641-466: 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

#216783