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SR-71 Blackbird

SR-71 Blackbird

Overview


The Lockheed SR-71 "Blackbird" was an advanced, long-range, Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...

 3+ strategic reconnaissance aircraft
Reconnaissance aircraft
A reconnaissance aircraft is a manned military aircraft designed, or adapted, to carry out aerial reconnaissance.-History:The majority of World War I aircraft were reconnaissance designs...

. It was developed as a black project
Black project
In the United States and United Kingdom, a black project is in the vernacular a classified military/defense project, unacknowledged publicly by the government, military personnel, and defense contractors. Examples of U.S...

 from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed
Lockheed Corporation
The Lockheed Corporation was an American aerospace company. Lockheed was founded in 1912 and later merged with Martin Marietta to form Lockheed Martin in 1995.-Origins:...

 Skunk Works
Skunk works
Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...

. Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. During reconnaissance missions the SR-71 operated at high speeds and altitudes to allow it to outrace threats.
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Encyclopedia


The Lockheed SR-71 "Blackbird" was an advanced, long-range, Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...

 3+ strategic reconnaissance aircraft
Reconnaissance aircraft
A reconnaissance aircraft is a manned military aircraft designed, or adapted, to carry out aerial reconnaissance.-History:The majority of World War I aircraft were reconnaissance designs...

. It was developed as a black project
Black project
In the United States and United Kingdom, a black project is in the vernacular a classified military/defense project, unacknowledged publicly by the government, military personnel, and defense contractors. Examples of U.S...

 from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed
Lockheed Corporation
The Lockheed Corporation was an American aerospace company. Lockheed was founded in 1912 and later merged with Martin Marietta to form Lockheed Martin in 1995.-Origins:...

 Skunk Works
Skunk works
Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...

. Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. During reconnaissance missions the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

 launch was detected, the standard evasive action was simply to accelerate and outrun the missile.

The SR-71 served with the U.S. Air Force from 1964 to 1998. Although 12 of the 32 aircraft built were destroyed in accidents, none were lost to enemy action. The SR-71 was unofficially named the Blackbird, and called the Habu
Trimeresurus flavoviridis
Trimeresurus flavoviridis is a venomous pitviper species found in Japan in the Ryukyu Islands. No subspecies are currently recognized.-Description:...

by its crews, referring to an Okinawan species of pit viper. Since 1976, it has held the world record for the fastest air-breathing manned aircraft, a record previously held by the YF-12
Lockheed YF-12
The Lockheed YF-12 was an American prototype interceptor aircraft, which the United States Air Force evaluated as a development of the highly-secret Lockheed A-12 that also spawned the SR-71 Blackbird.-Design and development:...

.

Background


Lockheed's previous reconnaissance aircraft was the U-2
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

, which was designed for the Central Intelligence Agency
Central Intelligence Agency
The Central Intelligence Agency is a civilian intelligence agency of the United States government. It is an executive agency and reports directly to the Director of National Intelligence, responsible for providing national security intelligence assessment to senior United States policymakers...

 (CIA). In 1960, while overflying the USSR, Francis Gary Powers' U-2 was shot down by Soviet surface-to-air missile
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

s (SAMs). This highlighted the U-2's vulnerability due to its relatively slow speed; this paved the way for the Lockheed A-12, also designed for the CIA by Clarence Johnson at Lockheed's Skunk Works
Skunk works
Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...

. The A-12 was the precursor of the SR-71. The A-12's first flight took place at Groom Lake
Groom Lake
Groom Lake is a salt flat in Nevada used for runways of the Nellis Bombing Range Test Site airport on the north of the Area 51 USAF military installation. The lake at elevation is ~ from north to south and from east to west at its widest point...

 (Area 51), Nevada, on 25 April 1962. It was equipped with the less powerful Pratt & Whitney J75 engines due to protracted development of the intended Pratt & Whitney J58
Pratt & Whitney J58
The Pratt & Whitney J58 was a jet engine used on the Lockheed A-12, and subsequently on the YF-12 and SR-71 Blackbird aircraft. The J58 was a variable cycle engine which functioned as both a turbojet and a fan-assisted ramjet. The J58 was a single-spool turbojet engine with an afterburner...

. The J58s were retrofitted as they became available, and became the standard power plant for all subsequent aircraft in the series (A-12, YF-12, M-21) as well as the follow-on SR-71 aircraft.

Thirteen A-12s were built. Two A-12 variants were also developed, including three YF-12A
Lockheed YF-12
The Lockheed YF-12 was an American prototype interceptor aircraft, which the United States Air Force evaluated as a development of the highly-secret Lockheed A-12 that also spawned the SR-71 Blackbird.-Design and development:...

 interceptor prototypes, and two M-21 drone carrier variants. The cancellation of A-12 program was announced on 28 December 1966, due to budget concerns, and because of the forthcoming SR-71. The A-12 flew missions over Vietnam and North Korea before its retirement in 1968.

SR-71


The SR-71 designator is a continuation of the pre-1962 bomber series, which ended with the XB-70 Valkyrie
XB-70 Valkyrie
The North American Aviation XB-70 Valkyrie was the prototype version of the proposed B-70 nuclear-armed deep-penetration strategic bomber for the United States Air Force's Strategic Air Command...

. During the later period of its testing, the B-70 was proposed for a reconnaissance/strike role, with an RS-70 designation. When it was clear that the A-12 performance potential was much greater, the Air Force ordered a variant of the A-12 in December 1962. Originally named R-12 by Lockheed, the Air Force version was longer and heavier than the A-12, with a longer fuselage to hold more fuel, two seats in the cockpit, and reshaped chines. Reconnaissance equipment included signals intelligence sensors, a side-looking radar and a photo camera. The CIA's A-12 remained a better photo reconnaissance platform than the Air Force's R-12, however, especially since the A-12 flew higher and faster, and with only one pilot it had room to carry a superior camera and more instruments.

During the 1964 campaign, Republican presidential nominee Barry Goldwater
Barry Goldwater
Barry Morris Goldwater was a five-term United States Senator from Arizona and the Republican Party's nominee for President in the 1964 election. An articulate and charismatic figure during the first half of the 1960s, he was known as "Mr...

 repeatedly criticized President Lyndon B. Johnson
Lyndon B. Johnson
Lyndon Baines Johnson , often referred to as LBJ, was the 36th President of the United States after his service as the 37th Vice President of the United States...

 and his administration for falling behind the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 in developing new weapons. Johnson decided to counter this criticism by revealing the existence of the YF-12A Air Force interceptor (which also served as cover for the still-secret A-12) and, on 25 July 1964, the Air Force reconnaissance model. Air Force Chief of Staff General Curtis LeMay
Curtis LeMay
Curtis Emerson LeMay was a general in the United States Air Force and the vice presidential running mate of American Independent Party candidate George Wallace in 1968....

 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 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.

This public disclosure of the program and its renaming came as a shock to everyone at the Skunk Works and to Air Force personnel involved in the program. All of the printed maintenance manuals, flight crew handbooks, training slides and materials were labeled "R-12" and 18 June 1965 Certificates of Completion issued by the Skunk Works to the first Air Force Flight Crews and their Wing Commander were labeled "R-12 Flight Crew Systems Indoctrination, Course VIII". The name change was taken as an order from the Commander-in-Chief, and immediate reprinting began of materials, including 29,000 blueprints, with the new name.

Design


A particularly difficult issue with flight at over Mach 3 is the high temperatures generated. As an aircraft moves through the air at supersonic speed, the air in front of the aircraft is compressed into a supersonic shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

, and the energy generated by this heats the airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

. To address this problem, high-temperature materials were needed, and the airframe of the SR-71 was substantially made of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

, obtained from the USSR
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 at the height of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

. Lockheed used many guises to prevent the Soviet government from knowing what the titanium was to be used for. In order to control costs, Lockheed used a more easily worked alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

 of titanium which softened at a lower temperature. Finished aircraft were painted a dark blue, almost black, to increase the emission of internal heat (fuel acted as a heat sink
Heat sink
A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...

 for avionics cooling) and to act as camouflage against the night sky. The aircraft was designed to minimize its radar cross-section, an early attempt at stealth design. The aircraft's call sign was "Blackbird", because of its dark color.

Air inlets


The air inlets allowed the plane to cruise at over Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...

 3.2, yet kept air flowing into the turbojet engines at a subsonic, Mach 0.5 speed. At the front of each inlet was a sharply pointed movable cone called a "spike" that was locked in its full forward position on the ground and when in subsonic flight. As the aircraft accelerated past Mach 1.6, an internal jackscrew
Jackscrew
A jackscrew is a type of jack which is operated by turning a leadscrew. In the form of a screw jack it is commonly used to lift heavy weights such as the foundations of houses, or large vehicles.-Advantages:...

 moved the spike as much as 26 inches (66 cm) to the rear.

The original air inlet computer was an analog design which, based on pitot-static, pitch, roll, yaw, and angle-of-attack inputs, would determine how much movement was required. By moving, the spike tip would withdraw the shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

, riding on it closer to the inlet cowling
Cowling
A cowling is the covering of a vehicle's engine, most often found on automobiles and aircraft.A cowling may be used:* for drag reduction* for engine cooling by directing airflow* as an air intake for jet engines* for decorative purposes...

 until it just touched slightly inside the cowling lip. In this position shock-wave spillage, causing turbulence over the outer nacelle
Nacelle
The nacelle is a cover housing that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the...

 and wing, was minimized while the spike shock-wave then repeatedly reflected between the spike centerbody and the inlet inner cowl sides. In doing so, shock pressures were maintained while slowing the air until a Mach 1 shock wave formed in front of the engine compressor.

The backside of this "normal" shock wave was subsonic air for ingestion into the engine compressor. This capture of the Mach 1 shock wave within the inlet was called "Starting the Inlet". Tremendous pressures would be built up inside the inlet and in front of the compressor face. Bleed tubes and bypass doors were designed into the inlet and engine nacelles to handle some of this pressure and to position the final shock to allow the inlet to remain "started". Air that is compressed by the inlet/shockwave interaction is diverted around the turbo machinery of the engine and directly into the afterburner where it is mixed and burned. This configuration is essentially a ramjet
Ramjet
A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of airbreathing jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill...

 and provides up to 70% of the aircraft's thrust at higher mach numbers.

Ben Rich
Ben Rich
Benjamin Robert Rich was the second director of Lockheed's Skunk Works from 1975 to 1991, succeeding its founder, Kelly Johnson. Regarded as the "father of stealth," Ben Rich was responsible for leading the development of the F-117, the first production stealth aircraft...

, the Lockheed Skunkworks designer of the inlets, often referred to the engine compressors as "pumps to keep the inlets alive" and sized the inlets for Mach 3.2 cruise (where the aircraft was at its most efficient design point). The additional "thrust" refers to the reduction of engine energy required to compress the airflow. One unique characteristic of the SR-71 is that the faster it went, the more fuel-efficient it was in terms of pounds burned per nautical mile traveled. An incident related by Brian Shul
Brian Shul
Brian Shul , is a Vietnam-era USAF fighter pilot and a retired major in the United States Air Force . He flew 212 combat missions and was shot down near the end of the war. He was so badly burned that he was given next to no chance to live. Surviving, he returned to full flight status, flying the...

, author of Sled Driver: Flying the World's Fastest Jet, was that on one reconnaissance run he was fired upon several times. In accordance with procedure they accelerated and maintained the higher than normal velocity for some time; afterwards they discovered that this had reduced their fuel consumption.

In the early years of the Blackbird programs the analog air inlet computers would not always keep up with rapidly changing flight environmental inputs. 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 flow of air through the engine compressor would immediately stop, thrust would drop, and exhaust gas temperatures would begin to rise. Due to the tremendous thrust of the remaining engine pushing the aircraft asymmetrically an unstart would cause the aircraft to yaw violently to one side. SAS, autopilot, and manual control inputs would fight the yawing, but often the extreme off-angle would reduce airflow in the opposite engine and cause it to begin "sympathetic stalls". The result would be rapid counter-yawing, often loud "banging" noises and a rough ride. The crews' pressure-suit helmets would sometimes bang on the cockpit canopies until the initial unstart motions subsided.

One of the standard counters to an inlet unstart was for the pilot to unstart both inlets. This stopped the aircraft's yawing and pitching, and allowed the pilot to restart the inlets. Lockheed implemented an electronic control to detect unstart conditions and perform this action without pilot intervention. The initial analog inlet control system was replaced by a digital system beginning in 1980. The new system prevented many of unstarts encountered during flights.

Airframe


Before the Blackbird, titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 was used only in high-temperature exhaust fairings and other small parts directly related to supporting, cooling, or shaping high-temperature areas on aircraft. However, up to 85% of the Blackbird's structure consisted of titanium, with the remaining 15% in composite materials. Such extensive use of these materials in aircraft construction was a first in the industry. The advances made by Lockheed in fabrication have been used subsequently throughout the industry in the design and production of high-speed aircraft, including most modern fighter types.

Titanium was difficult to work with, expensive, and scarce. Initially, 80% of the titanium delivered to Lockheed was rejected due to metallurgical contamination. One of the difficulties found was that welds made during the summer were corroding and degrading the titanium due to higher levels of chlorine in the local water supply during that season. The problem was solved by changing to using distilled water as welding coolant. Cadmium plated tools were also found to cause corrosion, and had to be replaced. Studies of the aircraft's titanium skin revealed that the metal was actually growing stronger over time, because of intense heating due to compression of the air, caused by the rapid flight of the vehicle, i.e. heat treatment
Heat treatment
Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass...

.

Major portions of the upper and lower inboard wing skin of the SR-71 were corrugated, not smooth. The thermal expansion stresses of a smooth skin would have caused splitting or curling. By making the surface corrugated, the skin was allowed to expand vertically and horizontally without overstressing, which also increased longitudinal strength. Despite its success, aerodynamicists initially opposed the concept and accused the design engineers of trying to make a 1920s era Ford Trimotor
Ford Trimotor
The Ford Trimotor was an American three-engined transport plane that was first produced in 1925 by the companies of Henry Ford and that continued to be produced until June 7, 1933. Throughout its time in production, a total of 199 Ford Trimotors were produced...

 — known for its corrugated aluminum skin — go Mach 3. The red stripes on some SR-71s are to prevent maintenance workers damaging the skin. The curved skin near the center of the fuselage is thin and delicate. There is no support underneath with exception of the structural ribs, which are spaced several feet apart.

To allow for thermal expansion at the high operational temperatures, the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was only achieved when the airframe heated due to air resistance at high speeds, causing the airframe to expand several inches. Because of this, and the lack of a fuel sealing system that could handle the thermal expansion of the airframe at extreme temperatures, the aircraft would leak JP-7
JP-7
JP-7 is a jet fuel developed by the U.S. Air Force for use in supersonic aircraft because of its high flash point and thermal stability. It is the fuel used in the Pratt & Whitney J58 engines, used in the Lockheed SR-71 Blackbird. The air compression of Mach 3+ cruising flight generates very high...

 jet fuel onto the runway before it took off. The aircraft would quickly make a short sprint, meant to warm up the airframe, and was then refueled in the air before departing on its mission. Cooling was carried out by cycling fuel behind the titanium surfaces at the front of the wings (chines). On landing after a mission the canopy temperature was over 300 °C (572 °F), too hot to approach. Non-fibrous asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...

 with high heat tolerance was used in high-temperature areas.

Stealth and threat avoidance


The SR-71 was the first operational aircraft designed around a stealthy shape and materials. There were a number of features in the SR-71 that were designed to reduce its radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 signature. The first studies in radar stealth technology
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

 seemed to indicate that a shape with flattened, tapering sides would avoid reflecting most radar energy toward the radar beams' place of origin. To this end, the radar engineers suggested adding chines to the design and canting the vertical control surfaces inward. The aircraft also used special radar-absorbing materials which were incorporated into sawtooth shaped sections of the skin of the aircraft, as well as cesium
Caesium
Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C , which makes it one of only five elemental metals that are liquid at room temperature...

-based fuel additives to reduce the exhaust plumes' visibility on radar. Despite these efforts, the SR-71 was still easily detected on radar while traveling at speed due to its large exhaust stream and air heated by the body (large thermal gradients in the atmosphere are detectable with radar). The SR-71's radar cross section
Radar cross section
Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...

 (RCS) of almost 10 square meters was much greater than the later F-117's RCS, which is similar to that of a small ball bearing.

The overall effectiveness of these designs is still debated; Ben Rich's team could show that the radar return was, in fact, reduced, but Kelly Johnson later conceded that Russian radar technology was advancing faster than the "anti-radar" technology Lockheed was using to counter it. The SR-71 made its debut years before Pyotr Ya. Ufimtsev's ground-breaking research made possible today's stealth technologies, and, despite Lockheed's best efforts, the SR-71 was still easy to track by radar and had a huge infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 signature when cruising at Mach 3.2 or more. It was visible on radar since air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...

 tracked it when not using its transponder, and missiles were often fired at the aircraft.

Although equipped with defensive electronic countermeasures, the SR-71's greatest protection was its high top speed, which made it almost invulnerable to the attack technologies of the time. Over the course of its service life, no SR-71 was shot down, despite many attempts to do so. It flew too fast and too high for surface-to-air missile systems to track and shoot down, and was much faster than the Soviet Union's fastest aircraft of the time, the MiG-25, which had a top speed of Mach 3.2 at high altitude, however the engines would burn up at that speed. All the SR-71 pilot had to do was to accelerate.

Chines


One of the Blackbird's interesting features was its chines, sharp edges leading aft on either side of the nose and along the sides of the fuselage.

The Blackbird was originally not going to have chines. At its A-3 design stage, the fuselage had a circular or vertical oval cross section. Dr. Frank Rodgers, of the Scientific Engineering Institute (a CIA front company), had discovered that a section of a sphere—round on the bottom and flat on top—had a greatly reduced radar reflection. He adapted this to a cylindrical fuselage by 'stretching' the sides out and leaving the bottom round. After 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, and used them in redesigning the A-11 into the A-12.

The aerodynamicists discovered that the chines generated powerful vortices
Vortex
A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...

 around themselves, generating much additional lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...

 near the front of the aircraft, leading to surprising improvements in aerodynamic performance. The angle of incidence of the delta wings could then be reduced, allowing for greater stability and less high-speed drag, and more weight (fuel) could be carried, allowing for greater range. Landing speeds were also reduced, since the chines' vortices created turbulent flow over the wings at high angles of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

, making it harder for the wings to stall
Stall (flight)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...

. The Blackbird can, consequently, make high-alpha
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

 turns to the point where the Blackbird's unique engine air inlets stop ingesting enough air, which can cause the engines to flame out
Flameout
A flameout refers to the failure of a jet engine caused by the extinction of the flame in the combustion chamber. It can be caused by a number of factors, including fuel exhaustion; compressor stall; insufficient oxygen supply; foreign object damage ; severe inclement weather; and mechanical...

. Blackbird pilots were thus warned not to pull more than 3 g
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...

, so that angles of attack stay low enough for the engines to get enough air. The chines act like the leading edge extensions that increase the agility of modern fighters such as the F-5, F-16, F/A-18, MiG-29
Mikoyan MiG-29
The Mikoyan MiG-29 is a fourth-generation jet fighter aircraft designed in the Soviet Union for an air superiority role. Developed in the 1970s by the Mikoyan design bureau, it entered service with the Soviet Air Force in 1983, and remains in use by the Russian Air Force as well as in many other...

 and Su-27
Sukhoi Su-27
The Sukhoi Su-27 is a twin-engine supermanoeuverable fighter aircraft designed by Sukhoi. It was intended as a direct competitor for the large United States fourth generation fighters, with range, heavy armament, sophisticated avionics and high manoeuvrability...

. The addition of chines also allowed designers to drop the planned canard
Canard (aeronautics)
In aeronautics, canard is an airframe configuration of fixed-wing aircraft in which the forward surface is smaller than the rearward, the former being known as the "canard", while the latter is the main wing...

 foreplanes. Early design models of what became the Blackbird featured canards.

When the Blackbird was being designed, no other airplane had featured chines, so Lockheed's engineers had to solve problems related to the differences in stability and balance caused by these unusual surfaces. Their solutions have since been extensively used. Chines remain an important design feature of many of the newest stealth UAVs, such as the Dark Star
RQ-3 Dark Star
-See also:- Footnotes :ReferencesSources* Specifications and second and third paragraphs: Display information on exhibit at Museum of Flight in Seattle, Washington, US.- External links :* *...

, Bird of Prey, X-45 and X-47, since they allow for tail-less stability as well as for stealth.

Fuel


Development began with using a coal slurry powerplant, but Johnson determined that the coal particles damaged engine components. He then began researching a liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...

 powerplant, but the tanks required to store cryogenic hydrogen
Cryogenic fuel
Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. Cryogenic fuels most often constitute liquefied gases such as liquid hydrogen....

 did not suit the Blackbird's size and shape.

The focus then became somewhat more conventional, though still specialized in many ways. The result was JP-7
JP-7
JP-7 is a jet fuel developed by the U.S. Air Force for use in supersonic aircraft because of its high flash point and thermal stability. It is the fuel used in the Pratt & Whitney J58 engines, used in the Lockheed SR-71 Blackbird. The air compression of Mach 3+ cruising flight generates very high...

 jet fuel, which had a relatively high flash point
Flash point
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source...

 (140 °F, 60 °C) to cope with the heat. The fuel was used as a coolant
Coolant
A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...

 and hydraulic fluid
Hydraulic fluid
Hydraulic fluids, also called hydraulic liquids, are the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water...

 in the aircraft before being burned. The fuel contained fluorocarbons to increase its lubricity, an oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...

 to enable it to burn in the engines, and even a cesium compound, A-50, which disguised the exhaust's radar signature.

JP-7 is very slippery, a disadvantage on the ground, because the aircraft leaked small amounts of fuel when not flying. However, JP-7 was not a fire hazard and was also extremely difficult to light in any conventional way. When the engines were started, puffs of triethylborane
Triethylborane
Triethylborane , also called triethylborine and triethylboron, is an organoborane , a near-colorless to yellowish transparent liquid with pungent ether-like odor. Its chemical formula can be written as C6H15B, or 3B, or 3B, or Et3B.Triethylborane is strongly pyrophoric, igniting spontaneously in...

 (TEB), which ignites on contact with air
Pyrophoricity
A pyrophoric substance is a substance that will ignite spontaneously in air. Examples are iron sulfide and many reactive metals including uranium, when powdered or sliced thin. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air...

, were injected into the engines to produce temperatures high enough to ignite the JP-7. The TEB produced a characteristic puff of greenish flame that could often be seen as the engines were ignited. TEB was also used to ignite the afterburner
AfterBurner
The AfterBurner is a lighting solution for the Game Boy Advance system that was created by Triton-Labs.Originally, portablemonopoly.net was a website created to petition Nintendo to put some kind of light in their Game Boy Advance system...

s. The aircraft carried 20 fluid ounces (600 ml) of TEB per engine, enough for at least 16 injections (a counter told the pilot how many TEB injections remained), more than enough for any missions it was likely to carry out.

Life support


Crews flying the SR-71 at 80000 ft (24,384 m) faced two main survival problems: maintaining consciousness at high altitude, and surviving ejection. With a standard pressure demand oxygen mask
Oxygen mask
An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover the nose and mouth or the entire face...

, human lungs cannot absorb oxygen quickly enough above 43000 ft (13,106.4 m). The pressure difference inside the mask versus the cockpit pressure on the chest also makes exhalation extremely difficult. In addition, emergency ejection at Mach 3.2 would expose the pilot to an instant heat rise pulse of approximately 450 °F (232.2 °C) as a result of the air flow. To solve these problems, the David Clark Company
David Clark Company
David Clark Company, Inc. is an American manufacturer, best known for noise attenuating headsets with boom microphones for use in military aviation, commercial aviation, industry and professional communication in high-noise environments...

 was hired to produce protective full pressure suits for the A-12, YF-12
Lockheed YF-12
The Lockheed YF-12 was an American prototype interceptor aircraft, which the United States Air Force evaluated as a development of the highly-secret Lockheed A-12 that also spawned the SR-71 Blackbird.-Design and development:...

, MD-21
Lockheed D-21/M-21
The Lockheed D-21 was an American Mach 3+ reconnaissance drone. The D-21 was initially designed to be launched from the back of its M-21 carrier aircraft, a variant of the Lockheed A-12 aircraft. Development began in October 1962...

 and SR-71 aircraft. These suits were later adapted for use on the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

.

In addition, cruising at Mach 3.2 would heat the aircraft's external surface well above 500 °F (260 °C) and the inside of the windshield to 250 °F (121.1 °C), so a robust coolant system was vital. This was achieved with an air conditioner, which used a heat exchanger to dump heat from the cockpit into the fuel prior to combustion.

After a high altitude bailout, an onboard oxygen supply would keep the suit pressurized. The crew member would then free-fall to 15000 ft (4,572 m) before the main parachute was opened, allowing heat to bleed off. To demonstrate this full pressure suit capability, crew members would wear one of these suits and undergo an altitude chamber explosive decompression at 78000 ft (23,774.4 m) or higher while chamber heaters would be turned on to 450 °F (232.2 °C), gradually decreasing at the expected rate in real life free-fall.

The cabin could be pressurized to an altitude of 10000 ft (3,048 m) or 26000 ft (7,924.8 m) during flight. So, crews flying a low-subsonic flight (such as a ferry mission) would wear either standard USAF hard hat helmets, pressure demand oxygen masks and nomex
Nomex
Nomex is a registered trademark for flame resistant meta-aramid material developed in the early 1960s by DuPont and first marketed in 1967.- Properties:...

 flying suits, or a full pressure suit.

Engines



The Pratt & Whitney J58-P4
Pratt & Whitney J58
The Pratt & Whitney J58 was a jet engine used on the Lockheed A-12, and subsequently on the YF-12 and SR-71 Blackbird aircraft. The J58 was a variable cycle engine which functioned as both a turbojet and a fan-assisted ramjet. The J58 was a single-spool turbojet engine with an afterburner...

 engines used in the Blackbird were the only American engines designed to operate continuously on afterburner, and became more efficient as speed increased. Each J58 engine could produce 32,500 lbf
Pound-force
The pound force is a unit of force in some systems of measurement including English engineering units and British gravitational units.- Definitions :...

 (145 kN) of static thrust. The J-58 engine for the SR-71 was a innovative marvel for its time (1950-1960s), using the most extreme materials available during that time period.

The J58 was unique in that it was a hybrid jet engine. It could operate as a regular turbojet at low speeds, but at high speeds it became a ramjet
Ramjet
A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of airbreathing jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill...

. The engine can be thought of as a turbojet engine inside a ramjet engine. At lower speeds, the turbojet provided most of the compression and most of the energy from fuel combustion. At higher speeds, the turbojet throttled back and sat in the middle of the engine as air passed around it, having been compressed by the shock cones and only burning fuel in the afterburner.

In detail, air was initially compressed (and thus also heated) by the shock cones, which generated shock waves that slowed the air down to subsonic speeds relative to the engine. The air then passed through four compressor stages and was split by movable vanes: some of the air entered the compressor fans ("core-flow" air), while the rest of the air went straight to the afterburner (via six bypass tubes). The air traveling through the turbojet was further compressed (and further heated), and then fuel was added to it in the combustion chamber: it then reached the maximum temperature anywhere in the Blackbird, just under the temperature where the turbine blades would start to soften. After passing through the turbine (and thus being cooled somewhat), the core-flow air went through the afterburner and met with any bypass air.

At around Mach 3, the increased heating from the shock cone compression, plus the heating from the compressor fans, was already enough to get the core air to high temperatures, and little fuel could be added in the combustion chamber without the turbine blades melting. This meant the whole compressor-combustor-turbine set-up in the core of the engine provided less power, and the Blackbird flew predominantly on air bypassed straight to the afterburners, forming a large ramjet effect.The maximum speed was limited by the specific maximum temperature for the compressor inlet of 800 °F (427 °C).

The J58 engines were most efficient around Mach 3.2, and this was the Blackbird's typical cruising speed.
Early 1990s studies of inlets of this type indicated that newer technology could allow for inlet speeds with a lower limit of Mach 6.

Startup


Originally, the Blackbird's engines started up with the assistance of an external engine referred to as a "start cart". The cart included two Buick
Buick
Buick is a premium brand of General Motors . Buick models are sold in the United States, Canada, Mexico, China, Taiwan, and Israel, with China being its largest market. Buick holds the distinction as the oldest active American make...

 Wildcat
Buick Wildcat
In 1966 a one-year-only Wildcat "Gran Sport Performance Group" package could be ordered by selecting the "A8/Y48" option. Two engine choices were available. The single carb 425 CID/340 hp V8 was included in the base package price but a dual-carb set-up was also available at extra cost...

 V8 engines positioned underneath the aircraft. The two engines powered a single, vertical driveshaft connecting to a single J58 engine. Once one engine was started, the cart was wheeled to the other side of the aircraft to start the other engine. The operation was deafening. Later big block Chevrolet engines were used. Eventually, a quieter, pneumatic start system was developed for use at Blackbird main operating bases, but the start carts remained in the inventory to support recovery team Blackbird starts at diversion landing sites not equipped to start J-58 engines.

Astro-Inertial Navigation System (ANS)


Blackbird precision navigation requirements for route accuracy, sensor pointing and target tracking preceded the development and fielding of the Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 (GPS). U-2 and A-12 Inertial Navigation Systems  existed, but US Air Force planners wanted a system that would limit inertial position error growth for longer missions envisioned for the R-12 / SR-71.

Nortronics, the electronics development organization of Northrop, had extensive astro-inertial experience, having provided an earlier generation system for the USAF Snark
SM-62 Snark
-External links:** Air Force Magazine article about a Snark that was test-fired and rumored to have been found in Brazil** detailed article on Snark and the USAF school to train personnel for it...

 missile. With this background, Nortronics developed the Astro-Inertial Navigation System for the AGM-48 Skybolt
AGM-48 Skybolt
The Douglas GAM-87 Skybolt was an air-launched ballistic missile , equipped with a nuclear warhead, developed by the United States during the late 1950s. The UK joined the program in 1960, intending to use it on their V bomber force...

 missile, which was to be launched from B-52H bombers. When the Skybolt Program was cancelled in December 1962, the assets Nortronics developed for the Skybolt Program were ordered to be adapted for the Blackbird program. A Nortronics "Skunkworks" type organization in Hawthorne, California completed the development of this system, sometimes referred to as the NAS-14 and/or the NAS-21.

The ANS primary alignment was done on the ground and was time consuming, but brought the inertial components to a high degree of accuracy for the start of a mission. A "blue light" source star tracker, which could detect and find stars during day or night, would then continuously track stars selected from the system's digital computer ephemeris
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...

 as the changing aircraft position would bring them into view. Originally equipped with data on 56 selected stars, the system would correct inertial orientation errors with celestial observations. The resulting leveling accuracies limited accelerometer errors and position growth.

Rapid ground alignments and air-start abilities were later developed and added to the ANS. Attitude and position inputs to on-board systems and flight controls included the Mission Data Recorder, Auto-Nav steering between loaded destination points, automatic pointing and control of cameras at control points and optical or SLR sighting of fix points (this mission data being tape loaded into the ANS prior to takeoff).

The ANS was located behind the Reconnaissance Systems Officer (RSO) station and tracked stars through a round quartz window in the upper fuselage. Cooling in the Blackbird Mach 3.2+ cruising environment was a serious challenge, resolved by Lockheed and Nortronics engineers during the early test phases. The ANS was a reliable and accurate self-contained navigation system.

Note: The original B-1A Offensive Avionics Request For Proposal (RFP) required the installation and integration of an NAS-14 system, but cost-cutting changes later deleted it from the B-1. Some U-2Rs did receive the NAS-21 system, but newer Inertial and GPS systems replaced them.

Sensors and payloads


Original capabilities for the SR-71 included optical/infrared imagery systems, side-looking airborne radar (SLAR), electronic intelligence (ELINT) gathering systems, defensive systems (for countering missile and airborne fighter threats) and recorders for SLAR, ELINT and maintenance data.

Imagery systems used on the Blackbird were diverse. At the simple end of the spectrum, SR-71s were equipped with a Fairchild tracking camera of modest resolution and an HRB Singer
HRB Systems
HRB Systems Inc., now part of Raytheon Intelligence and Information Systems, is a defense contractor located in State College, Pennsylvania. The company was started by three scientists: Haller, Raymond, and Brown. Initially, the firm provided imagery support, then transitioned to signal analysis...

 infrared-tracking IR camera, both of which ran during the entire mission to document where the aircraft flew and answer any post-flight political charges of overflight.

While the A-12's principal sensor was a single large focal length optical camera located in the "Q-Bay", behind the pilot, that location was taken by the cockpit for the observer in the SR-71, forcing the use of different camera systems, which could be located in the wing chines or in the interchangeable nose of the aircraft. Wide area imaging was provided by two of Itek
Itek
Itek Corporation was a US defense contractor that initially specialized in the field of camera systems for spy satellites. In the early 1960s they built a conglomerate in a fashion similar to LTV or Litton, during which time they developed the first CAD system and explored optical disk technology...

's Operational Objective Cameras (OOC) that provided stereo imagery left and right of the flight track, or an Itek Optical Bar Camera (OBC) that replaced the OOCs and was carried in the nose in place of the SLR, which gave continuous horizon-to horizon coverage. A closer view of the target area was given by the HYCON Technical Objective Camera (TEOC), that could look straight down or up to 45 degrees left or right of centerline. SR-71s were equipped with two of them, each with a six-inch (152 mm) resolution and the ability to show such details as the painted lines in parking lots from an altitude of 83000 feet (25,298.4 m). During the early years of service, the resolution produced by the smaller TEOCs was less than that of the larger camera carried by the A-12, although improvements in the camera and the film used later greatly improved the cameras performance. In the later years of the SR-71 operation, usage of the infrared camera was discontinued.

Side-looking radar, built by Goodyear Aerospace
Goodyear Aerospace
Goodyear Aerospace Corporation was the aerospace and defense subsidiary of Goodyear.-Early Years:The company began as Goodyear Tire & Rubber Co.’s Aeronautics Department and renamed in 1917 as the Goodyear Zeppelin Corporation set up to construct dirigibles for the US military...

 in Arizona, was carried in the removable nose section (which could be loaded with the SLR antenna in the maintenance shop before installation on the Blackbird). It was eventually replaced by Loral's Advanced Synthetic Aperture Radar System (ASARS-1) and built and supported by Goodyear. Both the first SLR and ASARS-1 were ground mapping imaging systems and could collect data in fixed swaths left or right of centerline or from a spot location where higher resolution was desired. As an example, in passing abeam of an open door aircraft hangar, ASARS-1 could provide meaningful data on the hangar's contents.

ELINT gathering systems, called the Electro Magnetic Reconnaissance System (EMR) built by AIL could be carried in both the left and right chine bays to provide a wide view of the electronic signal fields the Blackbird was flying through. Computer-loaded instructions looked for items of special intelligence interest.

Defensive systems built by several leading electronic countermeasures
Electronic countermeasures
An electronic countermeasure is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared or lasers. It may be used both offensively and defensively to deny targeting information to an enemy...

 (ECM) companies included (and evolved over the years of the Blackbird's operational life) Systems A, A2, A2C, B, C, C2, E, G, H and M. Several of these different frequency/purpose payloads would be loaded for a particular mission to match the threat environment expected for that mission. They, their warning and active electronic capabilities, and the Blackbird's ability to accelerate and climb when under attack, resulted in the SR-71's long and proven survival track-record.

Recording systems captured SLR phase shift history data (for ground correlation after landing), ELINT-gathered data, and Maintenance Data Recorder (MDR) information for post-flight ground analysis of the aircraft and its systems' overall health. From an altitude of 80000 feet (24,384 m), it could survey 100000 square miles (258,998.8 km²) per hour of the Earth's surface.

In the later years of its operational life, a data-link system was added that would allow ASARS-1 and ELINT data from about 2000 nmi (3,704 km) of track coverage to be downlinked if the SR-71 was within "contact" with a mutually equipped ground station.

Operational history


The first flight of an SR-71 took place on 22 December 1964, at Air Force Plant 42
Plant 42
Air Force Plant 42 is a federally owned military aerospace facility under the control of the Air Force Material Command in Palmdale, California...

 in Palmdale, California
Palmdale, California
Palmdale is a city located in the center of northern Los Angeles County, California, United States.Palmdale was the first community within the Antelope Valley to incorporate as a city on August 24, 1962; 47 years later, voters approved creating a charter city in November, 2009. Palmdale is...

. The first SR-71 to enter service was delivered to the 4200th (later, 9th) Strategic Reconnaissance Wing at Beale Air Force Base
Beale Air Force Base
Beale Air Force Base is a United States Air Force base located approximately east of Marysville, California. Originally known as Camp Beale....

, California, in January 1966. The United States Air Force Strategic Air Command had SR-71 Blackbirds in service from 1966 through 1991.

SR-71s first arrived at the 9th SRW's Operating Location (OL-8) at Kadena Air Base
Kadena Air Base
, is a United States Air Force base in the towns of Kadena and Chatan and the city of Okinawa, in Okinawa Prefecture, Japan. Kadena Air Base is the hub of U.S. airpower in the Pacific, and home to the USAF's 18th Wing and a variety of associate units.-Units:The 18th Wing is the host unit at Kadena...

, Okinawa on 8 March 1968. These deployments were code named "Glowing Heat", while the program as a whole was code named "Senior Crown". Reconnaissance missions over North Vietnam were code named "Giant Scale".

On 21 March 1968, Major (later General) Jerome F. O'Malley
Jerome F. O'Malley
General Jerome Francis O'Malley was a United States Air Force four star general who served as Vice Chief of Staff, U.S. Air Force from 1982 to 1983; Commander in Chief, Pacific Air Forces from 1983 to 1984; and Commander, Tactical Air Command from 1984 to 1985...

 and Major Edward D. Payne flew the first operational SR-71 sortie
Sortie
Sortie is a term for deployment or dispatch of one military unit, be it an aircraft, ship, or troops from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission....

 in SR-71 serial number 61-7976 from Kadena AB, Okinawa. During its career, this aircraft (976) accumulated 2,981 flying hours and flew 942 total sorties (more than any other SR-71), including 257 operational missions, from Beale AFB; Palmdale, California
Palmdale, California
Palmdale is a city located in the center of northern Los Angeles County, California, United States.Palmdale was the first community within the Antelope Valley to incorporate as a city on August 24, 1962; 47 years later, voters approved creating a charter city in November, 2009. Palmdale is...

; Kadena Air Base
Kadena Air Base
, is a United States Air Force base in the towns of Kadena and Chatan and the city of Okinawa, in Okinawa Prefecture, Japan. Kadena Air Base is the hub of U.S. airpower in the Pacific, and home to the USAF's 18th Wing and a variety of associate units.-Units:The 18th Wing is the host unit at Kadena...

, Okinawa, Japan; and RAF Mildenhall
RAF Mildenhall
RAF Mildenhall is a Royal Air Force station located at Mildenhall in Suffolk, England. Despite its status as an RAF station, it primarily supports United States Air Force operations and is currently the home of the 100th Air Refueling Wing...

, England. The aircraft was flown to the National Museum of the United States Air Force
National Museum of the United States Air Force
The National Museum of the United States Air Force is the official museum of the United States Air Force located at Wright-Patterson Air Force Base northeast of Dayton, Ohio. The NMUSAF is the world's largest and oldest military aviation museum with more than 360 aircraft and missiles on display...

 near Dayton, Ohio
Dayton, Ohio
Dayton is the 6th largest city in the U.S. state of Ohio and the county seat of Montgomery County, the fifth most populous county in the state. The population was 141,527 at the 2010 census. The Dayton Metropolitan Statistical Area had a population of 841,502 in the 2010 census...

 in March 1990.

From the beginning of the Blackbird's reconnaissance missions over enemy territory (North Vietnam, Laos, etc.) in 1968, the SR-71s averaged approximately one sortie a week for nearly two years. By 1970, the SR-71s were averaging two sorties per week, and by 1972, they were flying nearly one sortie every day.

While deployed in Okinawa, the SR-71s and their aircrew members gained the nickname Habu
Trimeresurus flavoviridis
Trimeresurus flavoviridis is a venomous pitviper species found in Japan in the Ryukyu Islands. No subspecies are currently recognized.-Description:...

 (as did the A-12s preceding them) after a pit viper
Viperidae
The Viperidae are a family of venomous snakes found all over the world, except in Antarctica, Australia, Ireland, Madagascar, Hawaii, various other isolated islands, and above the Arctic Circle. All have relatively long, hinged fangs that permit deep penetration and injection of venom. Four...

 indigenous to Japan, which the Okinawans thought the plane resembled.

Swedish JA 37 Viggen fighter pilots, using the predictable patterns of SR-71 routine flights over the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

, managed to lock their radar on the SR-71 on numerous occasions. Despite heavy jamming from the SR-71, target illumination was maintained by feeding target location from ground-based radars to the fire-control computer in the Viggen. The most common site for the lock-on
Missile lock-on
Missile lock-on refers to a scenario where the guidance system for a missile can accurately track a target, and a fire-control system can calculate the required flightpath for the missile to hit the target...

 to occur was the thin stretch of international airspace between Öland
Öland
' is the second largest Swedish island and the smallest of the traditional provinces of Sweden. Öland has an area of 1,342 km² and is located in the Baltic Sea just off the coast of Småland. The island has 25,000 inhabitants, but during Swedish Midsummer it is visited by up to 500,000 people...

 and Gotland
Gotland
Gotland is a county, province, municipality and diocese of Sweden; it is Sweden's largest island and the largest island in the Baltic Sea. At 3,140 square kilometers in area, the region makes up less than one percent of Sweden's total land area...

 that the SR-71 used on the return flight.

Operational highlights for the entire Blackbird family (YF-12, A-12, and SR-71) as of about 1990 included:
  • 3,551 Mission Sorties Flown
  • 17,300 Total Sorties Flown
  • 11,008 Mission Flight Hours
  • 53,490 Total Flight Hours
  • 2,752 hours Mach 3 Time (Missions)
  • 11,675 hours Mach 3 Time (Total)


Only one crew member, Jim Zwayer, a Lockheed flight-test reconnaissance and navigation systems specialist, was killed in a flight accident. The rest of the crew members ejected safely or evacuated their aircraft on the ground.

The highly specialized tooling used in manufacturing the SR-71 was ordered to be destroyed in 1968 by then-Secretary of Defense Robert McNamara
Robert McNamara
Robert Strange McNamara was an American business executive and the eighth Secretary of Defense, serving under Presidents John F. Kennedy and Lyndon B. Johnson from 1961 to 1968, during which time he played a large role in escalating the United States involvement in the Vietnam War...

, per contractual obligations at the end of production. Destroying the tooling killed any chance of there being an F-12B, but also limited the SR-71 force to the 32 completed, the final SR-71 order having to be cancelled when the tooling was destroyed.

First retirement


In the 1970s, the SR-71 was placed under closer congressional scrutiny and, with budget concerns, the program was soon under attack. Both Congress and the USAF sought to focus on newer projects like the B-1 Lancer
B-1 Lancer
The Rockwell B-1 LancerThe name "Lancer" is only applied to the B-1B version, after the program was revived. is a four-engine variable-sweep wing strategic bomber used by the United States Air Force...

 and upgrades to the B-52 Stratofortress
B-52 Stratofortress
The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...

, whose replacement was being developed. While the development and construction of reconnaissance satellites was costly, their upkeep was less than that of the nine SR-71s then in service.

The SR-71 had never gathered significant supporters within the Air Force, making it an easy target for cost-conscious politicians. Also, parts were no longer being manufactured for the aircraft, so other airframes had to be cannibalized to keep the fleet airworthy. The aircraft's lack of a datalink
Data link
In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...

 (unlike the Lockheed U-2
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

) meant that imagery and radar data could not be used in real time, but had to wait until the aircraft returned to base. The Air Force saw the SR-71 as a bargaining chip which could be sacrificed to ensure the survival of other priorities. A general misunderstanding of the nature of aerial reconnaissance and a lack of knowledge about the SR-71 in particular (due to its secretive development and usage) was used by detractors to discredit the aircraft, with the assurance given that a replacement was under development. In 1988, Congress was convinced to allocate $160,000 to keep six SR-71s (along with a trainer model) in flyable storage that would allow the fleet to become airborne within 60 days. The USAF refused to spend the money. While the SR-71 survived attempts to be retired in 1988, partly due to the unmatched ability to provide high quality coverage of the Kola Peninsula
Kola Peninsula
The Kola Peninsula is a peninsula in the far northwest of Russia. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely to the north of the Arctic Circle and is washed by the Barents Sea in the north and the White Sea in the east and southeast...

 for the US Navy, the decision to retire the SR-71 from active duty came in 1989, with the SR-71 flying its last missions in October that year.

Funds were redirected to the financially troubled B-1 Lancer and B-2 Spirit programs. Four months after the plane's retirement, General Norman Schwarzkopf, Jr.
Norman Schwarzkopf, Jr.
General Herbert Norman Schwarzkopf KCB , also known as "Stormin' Norman" and "The Bear", is a retired United States Army General who, while he served as Commander of U.S. Central Command, was commander of the Coalition Forces in the Gulf War of 1991.-Early life:Schwarzkopf was born in Trenton, New...

, was told that the expedited reconnaissance which the SR-71 could have provided was unavailable during Operation Desert Storm. However, it was noted by SR-71 supporters that the SR-71B trainer was just coming out of overhaul and that one SR-71 could have been made available in a few weeks, and a second one within two months. Since the aircraft was recently retired, the support infrastructure was in place and qualified crews available. The decision was made by Washington not to bring the aircraft back.

Reactivation


Due to increasing unease about political conditions in the Middle East and North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...

, the U.S. Congress re-examined the SR-71 beginning in 1993. At a hearing of the Senate Committee on Armed Services, Senator J. James Exon
J. James Exon
John James "Jim" Exon was an American Democratic politician. He served as the 33rd Governor of Nebraska from 1971 to 1979, and as a U.S. Senator from Nebraska from 1979 to 1997. Exon was a Nebraska Democrat who never lost an election, and the only Democrat to hold his Nebraska's Senate Class 2 seat...

 asked Admiral Richard C. Macke
Richard C. Macke
Richard Chester Macke was a Naval Aviator, an Admiral in the United States Navy and Commander of United States Pacific Command from July 19, 1994 until January 31, 1996. He was fired from that post in November 1995, hours after making comments considered insensitive to reporters about the case of...

:
Macke replied,
Rear Admiral Thomas F. Hall addressed the question of why the SR-71 was retired, saying it was under "the belief that, given the time delay associated with mounting a mission, conducting a reconnaissance, retrieving the data, processing it, and getting it out to a field commander, that you had a problem in timeliness that was not going to meet the tactical requirements on the modern battlefield. And the determination was that if one could take advantage of technology and develop a system that could get that data back real time… that would be able to meet the unique requirements of the tactical commander." Hall stated that "the Advanced Airborne Reconnaissance System, which was going to be an unmanned UAV" would meet the requirements but was not affordable at the time. He said that they were "looking at alternative means of doing [the job of the SR-71]."

Macke told the committee that they were "flying U-2s
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

, RC-135s, [and] other strategic and tactical assets" to collect information in some areas.

Senator Robert Byrd
Robert Byrd
Robert Carlyle Byrd was a United States Senator from West Virginia. A member of the Democratic Party, Byrd served as a U.S. Representative from 1953 until 1959 and as a U.S. Senator from 1959 to 2010...

 and other Senators complained that the "better than" successor to the SR-71 had yet to be developed at the cost of the "good enough" serviceable aircraft. 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.

Congress' disappointment with the lack of a suitable replacement for the Blackbird was cited concerning whether to continue funding imaging sensors on the U-2. Congressional conferees stated the "experience with the SR-71 serves as a reminder of the pitfalls of failing to keep existing systems up-to-date and capable in the hope of acquiring other capabilities."

It was agreed to add $100 million to the budget to return three SR-71s to service, but it was emphasized that this "would not prejudice support for long-endurance UAVs
Unmanned aerial vehicle
An unmanned aerial vehicle , also known as a unmanned aircraft system , remotely piloted aircraft or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously, that is, as a self-directing entity...

 [such as the Global Hawk]." The funding was later cut to $72.5 million. The Skunk Works was able to return the aircraft to service under budget, coming in at $72 million.

Colonel Jay Murphy (USAF Retired) was made the Program Manager for Lockheed's reactivation plans. Retired Air Force Colonels Don Emmons and Barry MacKean were put under government contract to remake the plane's logistic and support structure. Still-active Air Force pilots and Reconnaissance Systems Officers (RSOs) who had worked with the aircraft were asked to volunteer to fly the reactivated planes. The aircraft was under the command and control of the 9th Reconnaissance Wing
9th Reconnaissance Wing
The 9th Reconnaissance Wing is a United States Air Force unit assigned to the Air Combat Command Eighth Air Force. It is stationed at Beale Air Force Base, California...

 at Beale Air Force Base
Beale Air Force Base
Beale Air Force Base is a United States Air Force base located approximately east of Marysville, California. Originally known as Camp Beale....

 and flew out of a renovated hangar at Edwards Air Force Base
Edwards Air Force Base
Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...

. 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.

Second retirement


The reactivation met much resistance: the Air Force had not budgeted for the aircraft, and UAV developers worried that their programs would suffer if money was shifted to support the SR-71s. Also, with the allocation requiring yearly reaffirmation by Congress, long-term planning for the SR-71 was difficult. In 1996, the Air Force claimed that specific funding had not been authorized, and moved to ground the program. Congress reauthorized the funds, but, in October 1997, President Bill Clinton
Bill Clinton
William Jefferson "Bill" Clinton is an American politician who served as the 42nd President of the United States from 1993 to 2001. Inaugurated at age 46, he was the third-youngest president. He took office at the end of the Cold War, and was the first president of the baby boomer generation...

 used the line-item veto
Line Item Veto Act of 1996
The Line Item Veto Act of 1996 enacted a line-item veto for the Federal government of the United States, but its effect was brief due to judicial review....

 to cancel the $39 million allocated for the SR-71. In June 1998, the Supreme Court of the United States
Supreme Court of the United States
The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...

 ruled that the line-item veto was unconstitutional
Clinton v. City of New York
Clinton v. City of New York, , is a legal case in which the Supreme Court of the United States ruled that the line-item veto as granted in the Line Item Veto Act of 1996 violated the Presentment Clause of the United States Constitution because it impermissibly gave the President of the United...

. All this left the SR-71's status uncertain until September 1998, when the Air Force called for the funds to be redistributed. The plane was permanently retired in 1998. The Air Force quickly disposed of their SR-71s, leaving NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 with the two last flyable Blackbirds until 1999. All other Blackbirds have been moved to museums except for the two SR-71s and a few D-21
Lockheed D-21/M-21
The Lockheed D-21 was an American Mach 3+ reconnaissance drone. The D-21 was initially designed to be launched from the back of its M-21 carrier aircraft, a variant of the Lockheed A-12 aircraft. Development began in October 1962...

 drones retained by the NASA Dryden Flight Research Center
Dryden Flight Research Center
The Dryden Flight Research Center , located inside Edwards Air Force Base, is an aeronautical research center operated by NASA. On March 26, 1976 it was named in honor of the late Hugh L. Dryden, a prominent aeronautical engineer who at the time of his death in 1965 was NASA's deputy administrator...

.

SR-71 timeline


Important dates pulled from many sources.
  • 24 December 1957: First J58 engine run.
  • 1 May 1960: Francis Gary Powers is shot down in a Lockheed U-2
    Lockheed U-2
    The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

     over the Soviet Union.
  • 13 June 1962: SR-71 mock-up reviewed by Air Force.
  • 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 (#61-7950) delivered to Palmdale.
  • 7 December 1964: Beale AFB, CA announced as base for SR-71.
  • 22 December 1964: First flight of the SR-71 with Lockheed test pilot Bob Gilliland at AF Plant #42.
  • 21 July 1967: Jim Watkins and Dave Dempster fly first international sortie in SR-71A #61-7972 when the Astro-Inertial Navigation System (ANS) fails on a training mission and they accidentally fly into Mexican airspace.
  • 3 November 1967: A-12 and SR-71 conduct a reconnaissance fly-off. Results were questionable.
  • 5 February 1968: Lockheed ordered to destroy A-12, YF-12, and SR-71 tooling.
  • 8 March 1968: First SR-71A (#61-7978) arrives at Kadena AB to replace A-12s.
  • 21 March 1968: First SR-71 (#61-7976) operational mission flown from Kadena AB over Vietnam.
  • 29 May 1968: CMSgt Bill Gornik begins the tie-cutting tradition of Habu crews neck-ties.
  • 3 December 1975: First flight of SR-71A #61-7959 in "Big Tail" configuration.
  • 20 April 1976: TDY operations started at RAF Mildenhall in SR-71A #17972.
  • 27–28 July 1976 : SR-71A sets speed and altitude records (Altitude in Horizontal Flight: 85068.997 ft (25,929 m) and Speed Over a Straight Course: 2,193.167 mph).
  • August 1980: Honeywell
    Honeywell
    Honeywell International, Inc. is a major conglomerate company that produces a variety of consumer products, engineering services, and aerospace systems for a wide variety of customers, from private consumers to major corporations and governments....

     starts conversion of AFICS to DAFICS.
  • 15 January 1982: SR-71B #61-7956 flies its 1,000th sortie.
  • 21 April 1989: #974 was lost due to an engine explosion after taking off from Kadena AB. This was the last Blackbird to be lost, and was the first SR-71 accident in 17 years.
  • 22 November 1989: Air Force SR-71 program officially terminated.
  • 21 January 1990: Last SR-71 (#61-7962) left Kadena AB.
  • 26 January 1990: SR-71 is decommissioned at Beale AFB, CA.
  • 6 March 1990: Last SR-71 flight under SENIOR CROWN program, setting four speed records enroute to Smithsonian Institution.
  • 25 July 1991: SR-71B #61-7956/NASA #831 officially delivered to NASA Dryden.
  • October 1991: Marta Bohn-Meyer
    Marta Bohn-Meyer
    Marta Bohn-Meyer was an American pilot and engineer.Marta Bohn-Meyer served as chief engineer of the NASA Dryden Flight Research Center...

     becomes first female SR-71 crew member.
  • 28 September 1994: Congress votes to allocate $100 million for reactivation of three SR-71s.
  • 26 April 1995: First reactivated SR-71A (#61-7971) makes its first flight after restoration by Lockheed.
  • 28 June 1995: First reactivated SR-71 returns to Air Force as Detachment 2.
  • 28 August 1995: Second reactivated SR-71A (#61-7967) makes first flight after restoration.
  • 2 August 1997: A NASA SR-71 made multiple flybys at the EAA AirVenture Oshkosh air show. It was then supposed to perform a sonic boom at 53000 feet (16,154.4 m) after a midair refueling, but a fuel flow problem caused it to divert to Milwaukee. Two weeks later, the pilot's flight path brought him over Oshkosh again, and there was, in fact, a sonic boom.
  • 19 October 1997: The last flight of SR-71B #61-7956 at Edwards AFB Open House.
  • 9 October 1999: The last flight of the SR-71 (#61-7980/NASA 844).
  • September 2002: Final resting places of #956, #971, and #980 are made known.
  • 15 December 2003: SR-71 #972 goes on display at the Steven F. Udvar-Hazy Center
    Steven F. Udvar-Hazy Center
    The Steven F. Udvar-Hazy Center is the Smithsonian National Air and Space Museum 's annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia, United States....

     in Chantilly, Virginia
    Chantilly, Virginia
    Chantilly is an unincorporated community located in western Fairfax County and southeastern Loudoun County of Northern Virginia. Recognized by the U.S. Census Bureau as a census designated place , the community population was 23,039 as of the 2010 census -- down from 41,041 in 2000, due to the...

    .

Records


The SR-71 was the world's fastest and highest-flying operational manned aircraft throughout its career. On 28 July 1976, SR-71 serial number 61-7962 broke the world record for its class: an "absolute altitude record" of 85069 feet (25,929 m). Several aircraft exceeded this altitude in zoom climb
Zoom climb
A zoom climb is a climb where the rate of climb is greater than the maximum for a sustained climb, as determined from the thrust of the aircraft's engines. During a zoom climb, the aircraft accelerates to a high air speed at an altitude at which it can operate in sustained level flight. The pilot...

s but not in sustained flight. That same day SR-71, serial number 61-7958 set an absolute speed record of 1905.81 kn (2,320.9 mph; 3,735.1 km/h).

The SR-71 also holds the "Speed Over a Recognized Course" record for flying from New York to London distance 3508 miles (5,645.6 km), 1435.587 miles per hour (2,310.4 km/h), and an elapsed time of 1 hour 54 minutes and 56.4 seconds, set on 1 September 1974 while flown by U.S. Air Force Pilot Maj. James V. Sullivan and Maj. Noel F. Widdifield, reconnaissance systems officer (RSO). This equates to an average velocity of about Mach 2.68, including deceleration for in-flight refueling. Peak speeds during this flight were probably closer to the declassified top speed of Mach 3.2+. For comparison, the best commercial Concorde
Concorde
Aérospatiale-BAC Concorde was a turbojet-powered supersonic passenger airliner, a supersonic transport . It was a product of an Anglo-French government treaty, combining the manufacturing efforts of Aérospatiale and the British Aircraft Corporation...

 flight time was 2 hours 52 minutes, and the Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...

 averages 6 hours 15 minutes.

On 26 April 1971, 61-7968 flown by Majors Thomas B. Estes and Dewain C. Vick flew over 15000 miles (24,140.1 km) in 10 hrs. 30 min. This flight was awarded the 1971 Mackay Trophy
MacKay trophy
The Mackay Trophy was established on 27 January 1911 by Clarence Hungerford Mackay, who was then head of the Postal Telegraph-Cable Company and the Commercial Cable Company. Originally, aviators could compete for the trophy annually under rules made each year or the War Department could award the...

 for the "most meritorious flight of the year" and the 1972 Harmon Trophy
Harmon Trophy
The Harmon Trophy is a set of three international trophies, to be awarded annually to the world's outstanding aviator, aviatrix , and aeronaut...

 for "most outstanding international achievement in the art/science of aeronautics".
When the SR-71 was retired in 1990, one Blackbird was flown from its birthplace at United States Air Force Plant 42
Plant 42
Air Force Plant 42 is a federally owned military aerospace facility under the control of the Air Force Material Command in Palmdale, California...

 in Palmdale, California
Palmdale, California
Palmdale is a city located in the center of northern Los Angeles County, California, United States.Palmdale was the first community within the Antelope Valley to incorporate as a city on August 24, 1962; 47 years later, voters approved creating a charter city in November, 2009. Palmdale is...

, to go on exhibit at what is now the Smithsonian Institution
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...

's Steven F. Udvar-Hazy Center
Steven F. Udvar-Hazy Center
The Steven F. Udvar-Hazy Center is the Smithsonian National Air and Space Museum 's annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia, United States....

 in Chantilly, Virginia
Chantilly, Virginia
Chantilly is an unincorporated community located in western Fairfax County and southeastern Loudoun County of Northern Virginia. Recognized by the U.S. Census Bureau as a census designated place , the community population was 23,039 as of the 2010 census -- down from 41,041 in 2000, due to the...

. On 6 March 1990, Lt. Col. Raymond "Ed" E. Yielding and Lt. Col. Joseph "Jt" T. Vida piloted SR-71 S/N 61-7972 on its final Senior Crown flight and set four new speed records in the process.
  1. Los Angeles
    Los Ángeles
    Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...

    , CA
    California
    California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

     to Washington, D.C.
    Washington, D.C.
    Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

    , distance 2299.7 miles (3,701 km), average speed 2144.8 miles per hour (3,451.7 km/h), and an elapsed time of 64 minutes 20 seconds.
  2. West Coast
    West Coast of the United States
    West Coast or Pacific Coast are terms for the westernmost coastal states of the United States. The term most often refers to the states of California, Oregon, and Washington. Although not part of the contiguous United States, Alaska and Hawaii do border the Pacific Ocean but can't be included in...

     to East Coast
    East Coast of the United States
    The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...

    , distance 2404 miles (3,868.9 km), average speed 2124.5 miles per hour (3,419.1 km/h), and an elapsed time of 67 minutes 54 seconds.
  3. Kansas City, Missouri
    Kansas City, Missouri
    Kansas City, Missouri is the largest city in the U.S. state of Missouri and is the anchor city of the Kansas City Metropolitan Area, the second largest metropolitan area in Missouri. It encompasses in parts of Jackson, Clay, Cass, and Platte counties...

     to Washington D.C., distance 942 miles (1,516 km), average speed 2176 miles per hour (3,501.9 km/h), and an elapsed time of 25 minutes 59 seconds.
  4. St. Louis, Missouri
    St. Louis, Missouri
    St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

     to Cincinnati, Ohio
    Ohio
    Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

    , distance 311.4 miles (501.1 km), average speed 2189.9 miles per hour (3,524.3 km/h), and an elapsed time of 8 minutes 32 seconds.


These four speed records were accepted by the National Aeronautic Association
National Aeronautic Association
The National Aeronautic Association of the United States is a non-profit 501 organization and a member of the Fédération Aéronautique Internationale , the international standard setting and record-keeping body for aeronautics and astronautics. NAA is the official record-keeper for United States...

 (NAA), the recognized body for aviation records in the United States. After the Los Angeles–Washington flight, Senator John Glenn
John Glenn
John Herschel Glenn, Jr. is a former United States Marine Corps pilot, astronaut, and United States senator who was the first American to orbit the Earth and the third American in space. Glenn was a Marine Corps fighter pilot before joining NASA's Mercury program as a member of NASA's original...

 addressed the United States Senate
United States Senate
The United States Senate is the upper house of the bicameral legislature of the United States, and together with the United States House of Representatives comprises the United States Congress. The composition and powers of the Senate are established in Article One of the U.S. Constitution. Each...

, chastening the Department of Defense
United States Department of Defense
The United States Department of Defense is the U.S...

 for not using the SR-71 to its full potential:

Succession


Much speculation exists regarding a replacement for the SR-71, most notably aircraft identified as the Aurora. This is due to limitations of spy satellites, which are governed by the laws of orbital mechanics. It may take 24 hours before a satellite is in proper orbit to photograph a particular target, far longer than a reconnaissance plane. Spy planes can provide the most current intelligence information and collect it when lighting conditions are optimum. The fly-over orbit of spy satellites may also be predicted and can allow the enemy to hide assets when they know the satellite is above, a drawback spy planes lack. These factors have led many to doubt that the US has abandoned the concept of spy planes to complement reconnaissance satellites. Unmanned aerial vehicle
Unmanned aerial vehicle
An unmanned aerial vehicle , also known as a unmanned aircraft system , remotely piloted aircraft or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously, that is, as a self-directing entity...

s (UAVs) are also used for much aerial reconnaissance in the 2000s. They have the advantage of being able to overfly hostile territory without putting human pilots at risk.

Variants

  • The SR-71A was the main production variant.
  • The SR-71B was a trainer variant.
  • The SR-71C was a hybrid aircraft composed of the rear fuselage of the first YF-12A (S/N 60-6934) and the forward fuselage from a SR-71 static test unit. This Blackbird was seemingly not quite straight and had a yaw at supersonic speeds. It was nicknamed "The Bastard". The YF-12 had been wrecked in a 1966 landing accident.


Production of the SR-71 totaled 32 aircraft with 29 SR-71As, 2 SR-71Bs, and the single SR-71C.

Flight simulator


The Link Simulator Company's SR-71 Flight Simulator was developed during 1963–1965 under a deep "black" security blanket because it and the team Link assigned to it were given access to CIA OXCART and USAF R-12 / SR-71 clearances, the complete list of names of classified vendors supplying parts and software that had to be simulated, the total aircraft performance envelope data and a government-produced satellite photo montage of almost the entire continental United States to provide optical imagery for the RSO's portion of the Flight Simulator. This later capability was mounted on a separate, large, rectangular glass plate (approximately 6 feet (1.8 m) by 12 feet (3.7 m) in size) over which moved an optical sighting head that traveled at the scaled speed and direction of the Blackbird during its simulated flight. Realistic and accurate images were then displayed in the Optical View Sight and SLR RCD (Radar Correlator Display) in the RSO cockpit. Imagery was not provided to the pilot's simulator, which like the RSO simulator, had translucent window panels with varying degrees of lighting to change a simulated flight from daylight to night flying conditions.

Instructor positions were behind both the pilot's and the RSO's cockpits, with monitoring, malfunction and emergency problem controls provided. The simulator halves could be flown as separate cockpits with different training agendas or in a team mode, where intercom, instrument readings and air vehicle/sub-systems performance were integrated. Although most simulator flights were in a flight suit "shirt sleeve" environment, selected flights during a crew's checkout training were made with the crew wearing the complete David Clark Company's Full Pressure Suit.

In 1965, when the first Beale AFB Instructor Pilot/RSO crew (in civilian attire) visited the Flight Simulator during USAF checkout and acceptance trials at Link's upstate New York facilities, they were surprised to park in front of a busy, active grocery store and then be escorted to a side door that led to a hidden, rear portion of the building that was Link's classified "Skunkworks" type facility for the Blackbird program. Secrecy was so complete that no one in the township was aware of what was happening behind the busy checkout stands selling groceries. Later in 1965, the Flight Simulator was transferred to Beale AFB, California and the 9th Strategic Reconnaissance Wing's SAGE building, which provided vault level security for it plus the Wing Headquarters, Flight Mission Planning, and Intelligence Analysis / Exploitation of Blackbird mission products.

Besides SR-71 flight crew training and currency usage, the Flight Simulator was used several times by Lockheed and CIA operatives to analyze Groom Lake A-12 problems and accidents, with similar assistance provided for SR-71 flights at Edwards AFB. Another unique feature was that an actual flight mission tape for the SR-71 ANS could be loaded into the Flight Simulator's digital computers, which had been designed and programmed by Link engineers to emulate the Nortronics ANS. During Category II testing at Edwards AFB, some types of ANS navigation errors could be duplicated in the Flight Simulator at Beale AFB, with Link engineers then often assisting in software fixes to the main ANS flight software programs.

At the conclusion of SR-71 flying at Beale AFB, the Flight Simulator (minus the RSO optical imagery system) was transferred to the NASA Dryden facility at Edwards AFB in support of NASA SR-71 flight operations. Upon completion of all USAF and NASA SR-71 operations at Edwards, the Flight Simulator was moved in July 2006 to the Frontiers of Flight Museum
Frontiers of Flight Museum
The Frontiers of Flight Museum is an aerospace museum located in Dallas, Texas. The museum was founded in November 1988 by William E. Cooper, Kay Bailey Hutchison and Jan Collmer. Originally located within a terminal at Dallas Love Field, the museum now occupies a building at the Southeast corner...

 on Love Field Airport in Dallas, Texas and, with support from the Museum and Link (now, L-3 Communications, Link Simulation and Training), it is intended for viewing by Museum visitors.

Specifications (SR-71A)



Accidents and aircraft disposition


In total, 32 SR-71s were built. Twelve SR-71s were lost and one pilot died in accidents during the aircraft's service career. Eleven of these accidents happened between 1966 and 1972.
List of SR-71 Blackbirds
Serial numberModelLocation or fate
61-7950 SR-71A Lost, 10 January 1967
61-7951 SR-71A Pima Air & Space Museum
Pima Air & Space Museum
The Pima Air & Space Museum features a display of nearly 300 aircraft spread out over 80 acres on a campus occupying 127 acres . Located in Tucson, Arizona, it is one of the world's largest, non-government funded aerospace museums...

, Tucson, Arizona
Tucson, Arizona
Tucson is a city in and the county seat of Pima County, Arizona, United States. The city is located 118 miles southeast of Phoenix and 60 miles north of the U.S.-Mexico border. The 2010 United States Census puts the city's population at 520,116 with a metropolitan area population at 1,020,200...

61-7952 SR-71A Lost, 25 January 1966
61-7953 SR-71A Lost, 18 December 1969
61-7954 SR-71A Lost, 11 April 1969
61-7955 SR-71A Air Force Flight Test Center Museum, Edwards Air Force Base
Edwards Air Force Base
Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...

, California
61-7956 SR-71B Air Zoo
Air Zoo
The Air Zoo, founded as the Kalamazoo Aviation History Museum, is an aviation museum and indoor amusement park adjacent to the Kalamazoo-Battle Creek International Airport in Portage, Michigan....

, Kalamazoo, Michigan
Kalamazoo, Michigan
The area on which the modern city stands was once home to Native Americans of the Hopewell culture, who migrated into the area sometime before the first millennium. Evidence of their early residency remains in the form of a small mound in downtown's Bronson Park. The Hopewell civilization began to...

61-7957 SR-71B Lost, 11 January 1968
61-7958 SR-71A Museum of Aviation
Museum of Aviation
The Museum of Aviation is the second-largest aerospace museum of the United States Air Force. The museum is located just outside Warner Robins, Georgia, and near Robins Air Force Base. It has a total of five different buildings containing 93 different aircraft on . The SR-71A Blackbird on display...

, Warner Robins, Georgia
Warner Robins, Georgia
Warner Robins is a city in the U.S. state of Georgia, located primarily in Houston County with a small portion in Peach County. The city has its own metropolitan statistical area . As of the 2000 census, the city had a total population of 48,804...

61-7959 SR-71A Air Force Armament Museum
Air Force Armament Museum
The Air Force Armament Museum, adjacent to Eglin Air Force Base, Florida, is the only facility in the U.S. dedicated to the display of Air Force armament...

, Eglin Air Force Base
Eglin Air Force Base
Eglin Air Force Base is a United States Air Force base located approximately 3 miles southwest of Valparaiso, Florida in Okaloosa County....

, Florida
61-7960 SR-71A Castle Air Museum
Castle Air Museum
Castle Air Museum is a military aviation museum located in Atwater, California, United States adjacent to the site of the former Castle Air Force Base...

, Atwater, California
Atwater, California
Atwater is a city on U.S. Route 99 in Merced County, California, United States. Atwater is west-northwest of Merced, at an elevation of 151 feet . The population as of the 2010 census was 28,168.-Geography:...

61-7961 SR-71A Kansas Cosmosphere and Space Center
Kansas Cosmosphere and Space Center
The Kansas Cosmosphere and Space Center is a museum and educational facility in Hutchinson, Kansas that is best known for the display and restoration of spaceflight artifacts and educational camps...

, Hutchinson, Kansas
Hutchinson, Kansas
Hutchinson is the largest city in and the county seat of Reno County, Kansas, United States, northwest of Wichita, on the Arkansas River. It has been home to salt mines since 1887, thus its nickname of "Salt City", but locals call it "Hutch"...

61-7962 SR-71A American Air Museum in Britain, Imperial War Museum Duxford
Imperial War Museum Duxford
Imperial War Museum Duxford is a branch of the Imperial War Museum near the village of Duxford in Cambridgeshire, England. Britain's largest aviation museum, Duxford houses the museum's large exhibits, including nearly 200 aircraft, military vehicles, artillery and minor naval vessels in seven...

, Cambridgeshire
Cambridgeshire
Cambridgeshire is a county in England, bordering Lincolnshire to the north, Norfolk to the northeast, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west...

, England
61-7963 SR-71A Beale Air Force Base
Beale Air Force Base
Beale Air Force Base is a United States Air Force base located approximately east of Marysville, California. Originally known as Camp Beale....

, Marysville, California
Marysville, California
Marysville is the county seat of Yuba County, California, United States. The population was 12,072 at the 2010 census, down from 12,268 at the 2000 census. It is included in the Yuba City Metropolitan Statistical Area, often referred to as the Yuba-Sutter Area after the two counties, Yuba and...

61-7964 SR-71A Strategic Air and Space Museum
Strategic Air and Space Museum
The Strategic Air and Space Museum is a museum focusing on United States Air Force military aircraft and nuclear missiles located near Ashland, Nebraska, along Interstate 80 southwest of Omaha, Nebraska. The objective of the museum is to preserve and display historic aircraft, missile, and space...

, Ashland, Nebraska
Ashland, Nebraska
Ashland is a city in Saunders County, Nebraska, United States. The population was 2,262 at the 2000 census.- History :Ashland is located at the site of a low-water limestone ledge along the bottom of Salt Creek, an otherwise mud-bottomed stream that was a formidable obstacle for wagon trains on the...

61-7965 SR-71A Lost, 25 October 1967
61-7966 SR-71A Lost, 13 April 1967
61-7967 SR-71A Barksdale Air Force Base
Barksdale Air Force Base
Barksdale Air Force Base is a United States Air Force base located approximately east-southeast of Bossier City, Louisiana.The host unit at Barksdale is the 2d Bomb Wing , the oldest Bomb Wing in the Air Force. It is assigned to the Air Force Global Strike Command's Eighth Air Force...

, Bossier City, Louisiana
Bossier City, Louisiana
Bossier City is a city in Bossier Parish, Louisiana, United States.As of the 2010 Census, the city had a total population of 61,315. Bossier City is closely tied to its larger sister city Shreveport, located on the western bank of the Red River. The Shreveport-Bossier City metropolitan area is the...

61-7968 SR-71A Virginia Aviation Museum
Virginia Aviation Museum
The Virginia Aviation Museum is an aviation museum in Richmond, Virginia, adjacent to Richmond International Airport . The museum houses a collection of some thirty four airframes, both owned and on-loan, ranging from reproductions of Wright Brothers kite gliders to the still state-of-the-art SR-71...

, Richmond, Virginia
Richmond, Virginia
Richmond is the capital of the Commonwealth of Virginia, in the United States. It is an independent city and not part of any county. Richmond is the center of the Richmond Metropolitan Statistical Area and the Greater Richmond area...

61-7969 SR-71A Lost, 10 May 1970
61-7970 SR-71A Lost, 17 June 1970
61-7971 SR-71A Evergreen Aviation Museum
Evergreen Aviation Museum
The Evergreen Aviation & Space Museum is an aviation museum which displays a number of military and civilian aircraft and spacecraft, most notably, the Hughes H-4 Hercules "Spruce Goose". The museum is located in McMinnville, Oregon, across the street from the headquarters of Evergreen...

, McMinnville, Oregon
McMinnville, Oregon
McMinnville is the county seat and largest city of Yamhill County, Oregon, United States. According to Oregon Geographic Names, it was named by its founder, William T. Newby , an early immigrant on the Oregon Trail, for his hometown of McMinnville, Tennessee...

61-7972 SR-71A Steven F. Udvar-Hazy Center
Steven F. Udvar-Hazy Center
The Steven F. Udvar-Hazy Center is the Smithsonian National Air and Space Museum 's annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia, United States....

, Washington Dulles International Airport
Washington Dulles International Airport
Washington Dulles International Airport is a public airport in Dulles, Virginia, 26 miles west of downtown Washington, D.C. The airport serves the Baltimore-Washington-Northern Virginia metropolitan area centered on the District of Columbia. It is named after John Foster Dulles, Secretary of...

, Chantilly, Virginia
61-7973 SR-71A Blackbird Airpark, Palmdale, California
Palmdale, California
Palmdale is a city located in the center of northern Los Angeles County, California, United States.Palmdale was the first community within the Antelope Valley to incorporate as a city on August 24, 1962; 47 years later, voters approved creating a charter city in November, 2009. Palmdale is...

61-7974 SR-71A Lost, 21 April 1989
61-7975 SR-71A March Field Air Museum
March Field Air Museum
The March Field Air Museum is an aviation museum near Moreno Valley and Riverside, California, adjacent to March Air Reserve Base.-Origins:The museum was founded in 1979 as March Air Force Base Museum. Originally operated by the Air Force, the museum's operation was transferred to a nonprofit...

, Riverside, California
Riverside, California
Riverside is a city in Riverside County, California, United States, and the county seat of the eponymous county. Named for its location beside the Santa Ana River, it is the largest city in the Riverside-San Bernardino-Ontario metropolitan area of Southern California, 4th largest inland California...

61-7976 SR-71A National Museum of the United States Air Force
National Museum of the United States Air Force
The National Museum of the United States Air Force is the official museum of the United States Air Force located at Wright-Patterson Air Force Base northeast of Dayton, Ohio. The NMUSAF is the world's largest and oldest military aviation museum with more than 360 aircraft and missiles on display...

, Wright-Patterson Air Force Base
Wright-Patterson Air Force Base
Wright-Patterson Air Force Base is a United States Air Force base in Greene and Montgomery counties in the state of Ohio. It includes both Wright and Patterson Fields, which were originally Wilbur Wright Field and Fairfield Aviation General Supply Depot. Patterson Field is located approximately...

, near Dayton, Ohio
Dayton, Ohio
Dayton is the 6th largest city in the U.S. state of Ohio and the county seat of Montgomery County, the fifth most populous county in the state. The population was 141,527 at the 2010 census. The Dayton Metropolitan Statistical Area had a population of 841,502 in the 2010 census...

61-7977 SR-71A Lost, 10 October 1968
61-7978 SR-71A Lost, 20 July 1972
61-7979 SR-71A Lackland Air Force Base
Lackland Air Force Base
Lackland Air Force Base is a United States Air Force base located west-southwest of San Antonio, Texas. The base is under the jurisdiction of the 802d Mission Support Group, Air Education and Training Command ....

, San Antonio, Texas
San Antonio, Texas
San Antonio is the seventh-largest city in the United States of America and the second-largest city within the state of Texas, with a population of 1.33 million. Located in the American Southwest and the south–central part of Texas, the city serves as the seat of Bexar County. In 2011,...

61-7980 SR-71A Dryden Flight Research Center
Dryden Flight Research Center
The Dryden Flight Research Center , located inside Edwards Air Force Base, is an aeronautical research center operated by NASA. On March 26, 1976 it was named in honor of the late Hugh L. Dryden, a prominent aeronautical engineer who at the time of his death in 1965 was NASA's deputy administrator...

, Edwards Air Force Base
Edwards Air Force Base
Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...

, California
61-7981 SR-71C Hill Aerospace Museum
Hill Aerospace Museum
Hill Aerospace Museum, located near Ogden, Utah, is a U.S. Air Force museum that is part of the United States Air Force Heritage Program.The museum, founded in 1981 and moved to its current location in 1991, displays over 90 aircraft from around the world, in addition to a variety of munitions,...

, Hill Air Force Base
Hill Air Force Base
Hill Air Force Base is a major U.S. Air Force Base located in northern Utah, just south of the city of Ogden, and near the towns of Clearfield, Riverdale, Roy, Sunset, and Layton. It is about north of Salt Lake City. The base was named in honor of Major Ployer Peter Hill of the U.S. Army Air...

, Ogden, Utah
Ogden, Utah
Ogden is a city in Weber County, Utah, United States. Ogden serves as the county seat of Weber County. The population was 82,825 according to the 2010 Census. The city served as a major railway hub through much of its history, and still handles a great deal of freight rail traffic which makes it a...

 (formerly YF-12A 60-6934)


Notes:
  • Many secondary references use apparently incorrect 64- series aircraft serial numbers (e.g. SR-71C 64-17981), but no primary government documents have been found to support this.

See also


External links