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SR-71 Blackbird

2007 Schools Wikipedia Selection. Related subjects: Air & Sea transport

              Lockheed SR-71
   Type          Strategic Reconnaissance
   Manufacturer  Lockheed
   Designed by   Clarence "Kelly" Johnson
   Maiden flight December 22, 1964
   Introduced    1966
   Retired       1998
   Primary user  United States Air Force
   Number built  32

   The Lockheed SR-71, unofficially known as the Blackbird and by its
   crews as the Habu, was an advanced, long-range, Mach 3 strategic
   reconnaissance aircraft developed from the Lockheed YF-12A and A-12
   aircraft by the Lockheed Skunk Works (also responsible for the U-2). It
   flew from 1964–1998. Clarence "Kelly" Johnson was the man behind many
   of the design's advanced concepts. The SR-71 was one of the first
   aircraft to be shaped to reduce radar signature. However, the aircraft
   was not stealthy and still had a fairly large radar cross-section, and
   was visible on ATC radar for hundreds of miles, even when not using its
   transponder. This fact is further corroborated by the fact that
   missiles were fired at them quite often after they were detected on
   radar. The aircraft flew so fast and so high that if the pilot detected
   a surface-to-air missile launch, the standard evasive action was simply
   to accelerate. Twelve aircraft are known to have been lost, all through
   non-combat causes.

History

Predecessor models

   The A-12 Oxcart, designed for the CIA by Kelly Johnson at the Lockheed
   Skunk Works, was the precursor of the SR-71. Lockheed used the name
   "Archangel" for this design, but many documents use Johnson's preferred
   name for the plane, "the Article". As the design evolved, the internal
   Lockheed designation went from A-1 to A-12 as configuration changes
   occurred, such as substantial design changes to reduce the radar
   cross-section. The first flight took place at Groom Lake, NV, on April
   25, 1962. It was an Oxcart labeled the A-11 configuration since it was
   equipped with less powerful Pratt & Whitney J75s because development of
   the Pratt & Whitney J58s intended for the Oxcart was delayed. When the
   J58s finally arrived at the "Ranch" (Groom Lake's Area 51) and were
   installed, the Oxcart configuration number was changed to its final
   A-12 nomenclature (the J58s became the standard power-plant for all
   subsequent A-12s). Eighteen aircraft were built in three variations, of
   which three were YF-12As, prototypes of the planned F-12B interceptor
   version, and two were the M-21 variant (see below).

   The Air Force reconnaissance version was originally called the R-12
   (see the opening fly page in Paul Crickmore's book SR-71, Secret
   Missions Exposed, which contains a copy of the original R-12 labeled
   plan view drawing of the vehicle). However, during the 1964
   presidential campaign, Senator Barry Goldwater continually criticized
   President Lyndon B. Johnson and his administration for falling behind
   the Soviet Union in the research and development of new weapon systems.
   Johnson decided to counter this criticism with the public release of
   the highly classified A-12 program and later the existence of the
   reconnaissance version.

Name and designation

   The USAF had planned to redesignate the A-12 aircraft as the B-71 as
   the successor to the B-70 Valkyrie, which had two test Valkyries flying
   at Edwards AFB, California. The B-71 would have a nuclear capability of
   6 bombs. The next designation was RS-71 (Reconnaissance-Strike) when
   the strike capability became an option. However, then USAF Chief of
   Staff Curtis LeMay preferred the SR designation and wanted the RS-71 to
   be named SR-71. Before the Blackbird was to be announced by President
   Johnson on February 29, 1964, 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 myth that the president had misread the plane's designation.

   This public disclosure of the program and its designation came as a
   shock to everyone at Skunk Works and Air Force personnel involved in
   the program; at this time all of the printed Maintenance Manuals,
   Flight Crew Handbooks (the source of Paul Crickmoore's page), training
   vufoils, slides and materials were still labeled "R-12" (the June 18,
   1965 Certificate of Completion issued by the Skunkworks to the first
   Air Force Flight Crews and their Wing Commander are labeled: "R-12
   Flight Crew Systems Indoctrination, Course VIII" and signed by Jim
   Kaiser, Training Supervisor and Clinton P. Street, Manager, Flight Crew
   Training Department). Following Johnson's speech, the designation
   change was taken as an order from the Commander-in-Chief, and immediate
   republishing began of new materials retitled "SR-71" with 29,000
   blueprints altered.

First flight and usage

   Although the predecessor A-12 first flew in 1962, the first flight of
   an SR-71 took place on December 22, 1964, and the first SR-71 to enter
   service was delivered to the 4200th (later, 9th) Strategic
   Reconnaissance Wing at Beale Air Force Base, California, in January
   1966.

   The USAF Strategic Air Command had SR-71 Blackbirds in service from
   1966 through 1991.

   On March 21, 1968 Major (later General) Jerome F. O'Malley and Major
   Edward D. Payne flew the first operational SR-71 sortie in SR-71 serial
   number 61-7976. During its career, this aircraft (976) accumulated
   2,981 flying hours and flew 942 total sorties (more than any other
   SR-71), including 257 operational missions, from Beale AFB; Palmdale,
   California; Kadena Air Base, Okinawa, Japan; and RAF Mildenhall,
   England. The aircraft was flown to the United States Air Force Museum
   near Dayton, Ohio in March 1990.

   In a seventeen-year period of its operational history (from July 20,
   1972 to April 21, 1989) the SR-71 flew without a loss of any type.
   Other operational highlights:
     * 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)

   While deployed in Okinawa, the SR-71s and their aircrew members gained
   the nickname Habu (as did the A-12s preceding them) after a southeast
   Asian pit viper which the Okinawans thought the plane resembled.

   32 SR-71 airframes were built, 29 as SR-71As for operational missions
   and 2 as SR-71B trainers. The 32nd airframe was fabricated in 1969 as a
   hybrid trainer designated the SR-71C by mating the back half of an
   YF-12 wrecked in a 1966 landing accident with a fully functional SR-71
   forward section of a static test specimen. Of all SR-71s, 12 (including
   one trainer) were lost in flight (or ground) accidents. Only one crew
   member, Jim Zwayer, a Lockheed flight test reconnaissance and
   navigation systems specialist, was killed from a flight accident. The
   rest of the crew members ejected safely or evacuated their aircraft on
   the ground.

   The U.S. Air Force retired its fleet of SR-71s on January 26, 1990,
   allegedly because of a decreasing defense budget and high costs of
   operation. The reconnaissance aspect of the SR-71 could be performed
   cheaper, and often better by reconnaissance satellites and drones. The
   SR-71's performance was still unequalled, but eventually there were few
   things that it could do that could not be done by other devices, and it
   was very expensive to operate. Also, parts were no longer being
   manufactured for the aircraft, so other airframes had to be
   cannibalized in order to keep the fleet airworthy. The USAF returned
   the SR-71 to the active Air Force inventory in 1995 and began flying
   operational missions in January 1997. The planes were permanently
   retired in 1998.

   During the second Gulf war, there was a lack of on-demand overflight
   reconnaissance capability for finding SCUDs; other slower aircraft were
   too vulnerable to interception, and satellites were too predictable.
   Inquiries were made as to whether it would be possible to fly some more
   missions, but this turned out to be impractical.

SR-71 Timeline

   The SR-71 timeline here is a compilation of important dates pulled from
   many sources.
     * 24 December 1957: First J-58 engine run.
     * 1 May 1960: Francis Gary Powers is shot down in a U-2 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.
     * 2 July 1967: Jim Watkins and Dave Dempster fly first international
       sortie in SR-71A #61-7972 when the INS 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 (OL 8)
       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 Gormick 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: 85,068.997 ft. and Speed Over a Straight
       Course: 2,193.167 mph).
     * August 1980: Honeywell starts conversion of AFICS to DAFICS.
     * 15 January 1982: SR-71B #61-7956 flies its 1,000th sortie.
     * 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
       4 world records.
     * 25 July 1991: SR-71B #61-7956/NASA #831 officially delivered to
       NASA Dryden.
     * October 1991: Marta Bohn-Mayer 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 at
       Detachment 2.
     * 28 August 1995: Second reactivated SR-71A (#61-7967) makes first
       flight after restoration.
     * 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 is on first display at the National
       Air and Space Museum in Chantilly, Virginia.

Variants

   D-21B Drone mounted on M/D-21 Blackbird
   Enlarge
   D-21B Drone mounted on M/D-21 Blackbird

   One notable variant of the basic A-12 design was the M-21. This was an
   A-12 platform modified by replacing the single seat aircraft's Q bay
   (which carried its main camera) with a second cockpit for a launch
   control officer. The M-21 was used to carry and launch the D-21 drone,
   an unmanned, faster and higher flying reconnaissance device. This
   variant was known as the M/D-21 when mated to the drone for operations.
   The D-21 drone was completely autonomous; having been launched it would
   overfly the target, travel to a rendezvous point and eject its data
   package. The package would be recovered in midair by a C-130 Hercules
   and the drone would self destruct.

   The program to develop this system was canceled in 1966 after a drone
   collided with the mother ship at launch, destroying the M-21 and
   killing the Launch Control Officer. Three successful test flights had
   been conducted under a different flight regime; the fourth test was in
   level flight, considered an operational likelihood. The shock wave of
   the M-21 retarded the flight of the drone, which crashed into the
   tailplane. The crew survived the mid-air collision but the LCO drowned
   when he landed in the ocean and his flight suit filled with water.

   The only surviving M-21 is on display, along with a D-21B drone, at the
   Museum of Flight in Seattle, Washington. The D-21 was adapted to be
   carried on wings of the B-52 bomber.

   An additional D-21B drone is on display in the Spruce Goose museum in
   McMinnville, Oregon and yet another is parked on Celebrity Row at the
   Aircraft Maintanence And Regeneration Centre (AMARC) located nextdoor
   to Davis-Monthan AFB Tucson, Arizona.

Records

   The SR-71 remained the world's fastest and highest-flying operational
   manned aircraft throughout its career. From an altitude of 80,000 ft
   (24 km) it could survey 100,000 square miles per hour (72 square
   kilometers per second) of the Earth's surface. On July 28, 1976, an
   SR-71 broke the world record for its class: an absolute speed record of
   2,193.1669 mph (3,529.56 km/h), and a US "absolute altitude record" of
   85,068.997 feet (25,929 m). Several planes exceeded this altitude in
   zoom climbs but not in sustained flight. When the SR-71 was retired in
   1990, one was flown from its birthplace at United States Air Force
   Plant 42 in Palmdale to go on exhibit at what is now the Smithsonian
   Institution's Steven F. Udvar-Hazy Centre (an annex of the National Air
   & Space Museum) in Chantilly, Virginia, setting a coast-to-coast speed
   record at an average 2,124 mph (3,418 km/h). The entire trip took 64
   minutes. The SR-71 also holds the record for flying from New York to
   London: 1 hour 54 minutes and 56.4 seconds, set on September 1, 1974.
   This is only Mach 2.68, well below the declassified figure of 3.0+.
   (For comparison, commercial Concorde flights took around 3 hours 20
   minutes, and the Boeing 747 averages 6 hours.)

   It should be noted that any discussion of the SR-71's records and
   performance is limited to declassified information. Actual performance
   figures will remain the subject of speculation until additional
   information is released.

   This aircraft can be bought as a aeroplane model, also it has the D-21B
   Drone with the model kit

Design and operational details

   The flight instrumentation of SR-71 Blackbird
   Enlarge
   The flight instrumentation of SR-71 Blackbird

   The airframe was made of titanium obtained from the USSR during the
   height of the Cold War. Lockheed used all possible guises to prevent
   the Soviet government from knowing what the titanium was to be used
   for. In order to keep the costs under control, they used a more easily
   worked alloy of titanium which softened at a lower temperature.
   Finished aircraft were painted a dark blue (almost black) to increase
   the emission of internal heat (since fuel was used as a heat sink for
   avionics cooling) and to act as camouflage against the sky.

   The plane was designed to have a very small 'radar cross-section' — the
   SR-71 was an early stealth design. However, the radar signature aspects
   of the SR-71 design did not take into account the extremely hot engine
   exhaust, and it turns out that this exhaust can reflect radar.
   Ironically, the SR-71 was one of the largest targets on the FAA
   (Federal Aviation Administration) long range radars, which were able to
   track the plane at several hundred miles.

   The red stripes found on some SR-71s are there to prevent maintenance
   workers from damaging the skin of the aircraft. The curved skin near
   the centre of the fuselage is thin and delicate. There is no support
   underneath with exception of the structural ribs, which are spaced
   several feet apart.

Air inlets

   A critical design feature to allow cruising speeds of over Mach 3.0 ,
   yet provide subsonic air flow into the turbojet engines were the air
   inlets. At the front of each inlet was a sharp, pointed moveable cone
   called a "spike" that was locked in the full forward position on the
   ground or when in subsonic flight. During acceleration to high speed
   cruise, the spike would unlock at Mach 1.6 and then begin a mechanical
   (internal jackscrew powered) travel to the rear (as the shockwave
   "gamma" angle changed with increasing speed and to keep the shockwave
   reflecting off the internal wall in the same general area). It moved up
   to a maximum of 26 inches (66 cm). The original air inlet computer was
   an analog design which, based on pitot-static, pitch, roll, yaw,
   angle-of-attack inputs, would determine how much movement was required.
   By moving, the spike tip would withdraw the shockwave riding on it into
   the inlet body where reflections of the shockwave from the inlet cowl
   to the spike and back to the cowl would cause a loss of energy and slow
   it down until a Mach 1.0 shockwave was formed, the backside of which
   was subsonic air for ingestion into the engine compressor. This capture
   of the shockwave 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 holes and bypass doors were designed into
   the inlet and engine nacelles to handle some of this pressure and allow
   the inlet to remain "started". So significant was this inlet pressure
   build-up (pushing against the inlet structure) that at Mach 3.2 cruise,
   it was estimated that 58% of the available thrust was being provided by
   the inlet, 17% by the compressor and the remaining 25% by the
   afterburner. Ben Rich, 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
   travelled. One incident related by Brian Shul, author of Sled Driver:
   Flying the World's Fastest Jet, was that on one reconnaisance run he
   was fired upon several times. In accordance with procedure they
   accelerated and maintained the higher than normal velocity for some
   time, only to discover later that they were well ahead of their fuel
   curve.

   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 incorrectly positioned), the shockwave would suddenly blow out
   the front of the inlet, called an "Inlet Unstart". Immediately, the air
   flow through the engine compressor would cease, thrust dropped and
   exhaust gas temperatures would begin to rise. Due to the tremendous
   thrust of the remaining engine pushing the aircraft asymmetrically
   along with the sudden deceleration caused by losing 50% of available
   power, 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.
   Pilots and RSOs occasionally experienced their pressure suit helmets
   banging on their cockpit canopies until the initial unstart motions
   subsided.

   One of the standard counters to an inlet unstart was for the pilot to
   reach out and unstart both inlets; this drove both spikes out, stopped
   the yawing conditions and allowed the pilot to restart each inlet. Once
   restarted, with normal engine combustion, the crew would return to
   acceleration and climb to the planned cruise altitude.

   Eventually, a digital air inlet computer replaced the original analog
   one. Lockheed engineers developed control software for the engine
   inlets that would recapture the lost shockwave and re-light the engine
   before the pilot was even aware an unstart had occurred. The SR-71
   machinists were responsible for the hundreds of precision adjustments
   of the forward air by-pass doors within the inlets. This helped control
   the shock wave, prevent unstarts, and increase performance.

Fuselage

   Due to the great temperature changes in flight, the fuselage panels did
   not fit perfectly on the ground and were essentially loose. Proper
   alignment was only achieved when the airframe warmed up due to the 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 extreme temperatures, the aircraft would leak its JP-7
   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
   air-to-air refueled before departing on its mission. Cooling was
   carried out by cycling fuel behind the titanium surfaces at the front
   of the wings ( chines). Nonetheless, once the plane landed no one could
   approach it for some time as its canopy was still hotter than 300
   degrees Celsius. Non-fibrous asbestos was also used, as in non-ceramic
   automotive brakes, due to its high heat tolerance.

Stealth

   There were a number of features in the SR-71 that were designed to
   reduce its radar signature. The first studies in radar stealth seemed
   to indicate that a shape with flattened, tapering sides would reflect
   most radar away from the place where the radar beams originated. To
   this end the radar engineers suggested adding chines (see below) to the
   design and canting the vertical control surfaces inward. The plane also
   used special radar-absorbing materials which were incorporated into
   sawtooth shaped sections of the skin of the aircraft, as well as
   caesium-based fuel additives to reduce the exhaust plumes' visibility
   on radar. The overall effectiveness of these designs is still debated,
   but since the aircraft did not include other elements of today's
   stealth technologies, it was still easy to track by radar (and had a
   huge infrared signature when cruising at Mach 3+).

   Stealth features were useful mainly for intelligence purposes (hiding
   the fact that the aircraft was in use). The flight characteristics of
   the SR-71 made it virtually invulnerable to attempts to shoot it down
   during its service life, and in fact no SR-71 was ever shot down,
   despite over 4,000 attempts to do so.

Chines

   The chines themselves were an interesting and unique feature. The
   Blackbird was originally not going to have chines — it would have
   looked a little like an enlarged F-104 — but the radar engineers
   convinced the aerodynamicists to try adding them to a few wind-tunnel
   models during the design process, as the chines would supposedly reduce
   the aircraft's Radar Cross Section from many angles. The
   aerodynamicists discovered that the chines generated powerful vortices
   around themselves, generating much additional lift near the front of
   the aircraft. 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 these powerful vortices created
   turbulent flow over the wings at high angles of attack, making it
   harder for the wings to stall. (The Blackbird can, consequently, make
   high- alpha high- G turns to the point where the Blackbird's unique
   engine air inlets stop ingesting enough air, which can cause the
   engines to flame out. Blackbird pilots were thus warned not to pull
   more than 3Gs, so that angles of attack stay low enough for the engines
   to always get enough air). The chines act like the leading edge
   extensions which are used to increase the agility of many modern
   fighters such as the F-5, F-16, F/A-18, MiG-29 and Su-27. Once these
   advantages were observed during wind-tunnel tests of Blackbird models,
   the use of canard foreplanes was no longer needed. (Many early design
   models of what became the Blackbird featured canards.) Chines are still
   an important part of the design of many of the newest stealth UAVs,
   such as the Dark Star, Bird of Prey, X-45, and X-47, since they allow
   for tail-less stability as well as for stealth.

Fuel

   An air-to-air overhead front view of an SR-71A strategic reconnaissance
   aircraft. Note the water vapor, condensed by the low-pressure vortices
   generated by the chines ouboard of each engine inlet.
   Enlarge
   An air-to-air overhead front view of an SR-71A strategic reconnaissance
   aircraft. Note the water vapor, condensed by the low-pressure vortices
   generated by the chines ouboard of each engine inlet.

   SR-71 development began using a coal slurry powerplant, but Johnson
   determined that the coal particles damaged engine components. He then
   began researching a liquid hydrogen powerplant, but the tanks required
   to store cryogenic hydrogen did not suit the Blackbird's form factor.

   The focus then became somewhat more conventional, though still
   specialized in many ways. Originally developed for the A-12 Oxcart
   plane in the late 1950s, the JP-7 jet fuel had a relatively high flash
   point (60 °C) to cope with the heat. In fact, the fuel was used as a
   coolant and hydraulic fluid in the aircraft before being burned. The
   fuel also contained fluorocarbons to increase its lubricity, an
   oxidizing agent to enable it to burn in the engines, and even a cesium
   compound, A-50, which disguised the exhaust's radar signature. As a
   result, JP-7 was claimed to be more expensive than single malt Scotch
   whisky, which contributed to the $24-27,000/hr cost of operating the
   SR-71. For comparison, a U-2 costs only one-third as much. On the other
   hand, a U-2 travels at only one-fourth the speed, cannot carry as much
   reconnaissance equipment, and is much more vulnerable to interception.

   JP-7 is very slippery and extremely difficult to light in any
   conventional way. The slipperiness was a disadvantage on the ground,
   since the aircraft leaked fuel when not flying, but at least JP-7 was
   not a fire hazard. When the engines of the aircraft were started, puffs
   of triethylborane (TEB), which ignites on contact with air, were
   injected into the engines to produce temperatures high enough to
   initially ignite the JP-7. The TEB produced a characteristic cloud of
   greenish smoke that could often be seen as the engines were ignited.
   TEB was also used to ignite the afterburners. The aircraft had only a
   small and limited supply of TEB on board (a counter advised the pilot
   of the number of TEB injections remaining), but this was more than
   enough for the requirements of any missions it was likely to carry out.

Titanium skin

   Studies of the aircraft's titanium skin revealed the metal was actually
   growing stronger over time due to the intense heating caused by
   aerodynamic friction, a process similar to annealing.

   Major portions of the upper and lower inboard wing skin of the SR-71
   were actually corrugated, not smooth. The thermal expansion stresses of
   a smooth skin would have resulted in the aircraft skin splitting or
   curling. By making the surface corrugated, the skin was allowed to
   expand vertically as well as horizontally without overstressing, which
   also increased longitudinal strength. Despite the fact that it worked,
   aerodynamicists were initially aghast at the concept and accused the
   design engineers of trying to make a 1920s era Ford Trimotor — known
   for its corrugated aluminium skin — go Mach 3.

Engines

   Pratt & Whitney J58 engines beneath the SR-71 Blackbird on display at
   Imperial War Museum Duxford.
   Enlarge
   Pratt & Whitney J58 engines beneath the SR-71 Blackbird on display at
   Imperial War Museum Duxford.

   The Pratt & Whitney J58-1 engines used in the Blackbird were the only
   military engines ever designed to operate continuously on afterburner,
   and actually became more efficient as the aircraft went faster. Each
   J58 engine could produce 32,500 lb[f] (145 kN) of static thrust.
   Conventional jet engines cannot operate continuously on afterburner and
   lose efficiency as airspeed increases.

   The J58 was unique in that it was a hybrid jet engine: a turbojet
   engine inside a ramjet engine. At lower speeds the turbojet (engine
   core) and the ramjet (with the afterburners running without any bypass
   air) both work, but at higher speeds the turbojet throttled back and
   just sat in the middle with the air bypassed around it.

   Air was initially compressed (and thus also heated) by the shock cones,
   passed through 4 compressor stages and then was split by moveable
   vanes: some of the air entered the compressor fans ("core-flow" air),
   while the rest of the air went straight to the afterburner (via 6
   bypass tubes). The air travelling on through the turbojet was further
   compressed (and thus 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, were 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. No other aircraft does this. (This shows how the temperature
   tolerance of the turbine blades in a jet engine determine how much fuel
   can be burned, and thus to a great extent determine how much thrust a
   jet engine can provide.)

   Performance at low speeds was anaemia. Even passing the speed of sound
   required the aircraft to dive. The reason was that the size of the
   turbojets were traded to reduce weight but to still allow the SR-71 to
   reach speeds where the ramjet effect became prominent and efficient;
   and then the plane became alive and rapidly accelerated to Mach 3.0.
   The efficiency was then good due to high compression and low drag
   through the engine and this permitted large distances to be covered at
   high speed.

   Originally, the Blackbird's engines started up with the assistance of
   an external "start cart", a cart containing two Buick Wildcat V8
   engines which were rolled out onto the runway underneath the aircraft.
   The two Buick engines powered a single, vertical driveshaft connected
   to a single J58 engine. Once one engine was started, the cart was
   wheeled over to the other side of the aircraft to start the other
   engine. The operation was deafening. In later years, the J58s were
   started with a conventional start cart.

Astro-Inertial Navigation System (ANS)

   Blackbird precision navigation requirements for route accuracy, sensor
   pointing and target tracking preceded the development and fielding of
   GPS (the Global Position System and its family of position determining
   satellites). U-2 and A-12 Inertial Navigation Systems existed, but US
   Air Force planners wanted a system that would bound inertial position
   growth for longer missions envisioned for the R-12 / SR-71.

   Nortronics, the Electronic Development organization of Northrop, had
   extensive Astro-Inertial experience, and had provided an earlier
   generation system for the USAF Snark missile. With this background,
   Nortronics developed the Astro-Inertial Navigation System for the
   AGM-87 Skybolt missile, which was to be carried and launched from B-52H
   bombers. When the Skybolt Program was cancelled in December,1962, the
   Nortronics developed assets for the Skybolt Program were ordered to be
   adapted for the Blackbird program. A Nortronics "Skunkworks" type
   organization in Hawthorne, California completed the development and
   fielding of this system, sometimes referred to as the NAS-14 and/or the
   NAS-21.

   The ANS primary alignment was on the ground, and time consuming, but
   brought the inertial components to a high degree of level and accuracy
   for which to begin 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 as the changing aircraft position would bring them into view.
   Originally equipped with data on 56 selected stars, the system thus
   would correct inertial orientation errors with celestial observations.
   The resulting leveling accuracies obtained limited accelerometer errors
   and/or position growth.

   Rapid ground alignments and air start abilities were also 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/or 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 take-off).

   The ANS was located behind the RSO station and tracked stars through a
   round, quartz window seen in photos of the upper fuselage. Cooling in
   the Blackbird mach 3.0 + cruising environment was a serious development
   challenge, but solved by Lockheed and Nortronics engineers during the
   early test phases. The ANS became a highly reliable and accurate
   self-contained navigation system.

   Note: The original B-1A Offensive Avionics Request For Proposal (RFP)
   required the installation and integration of a NAS-14 system, but cost
   cutting changes later deleted it from the B-1. Some U2-Rs 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 Radar (SLR), Electronic Intelligence (ELINT)
   gathering systems, Defensive Systems (for countering Missile and
   Airborne Fighter threats) and recorders for SLR, Elint and Maintenance
   data.

   Optical/Infrared Imagery systems ranged from a Fairchild, modest
   resolution tracking camera and a HRB Singer 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), to two of ITEK's Operational Objective Cameras (OOC) that
   provided stereo imagery left and right of the flight track, an ITEK
   Optical Bar Camera (OBC) that replaced the OOC's but, was carried in
   the nose instead of the SLR, and two of HYCON's Technical Objective
   Cameras (TEOC) that could look straight down or up to 45 degrees left
   or right of centerline. The TEOC's had a 6 inch resolution and easily
   showed such details as the painted lines of car park stalls in car
   parking lots from 83,000 feet. In the later years of the SR-71's
   operational usage, the Infrared Camera use was discontinued.

   Side Looking Radar, built by Goodyear Aerospace 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 take could provide
   meaningful data on what was the hangar's contents or whether the hangar
   was empty.

   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
   (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 recorded 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 system's overall health (note: humorous stories
   accompanied some of the flight crew's discovery that the voice track in
   the MDR recorded interphone conversations between pilot and RSO and
   tanker aircraft crew members during refueling hook-ups).

   In later years of its operational life, a Data Link System was added
   that would allow ASARS-1 and ELINT data from about 2,000 nm of track
   coverage to be downlinked if the SR-71 was within "contact" with a
   mutually equipped ground station.

Flight Simulator

   The Link Simulator Company's SR-71 Flight Simulator was developed
   during the 1963 � 1965 time period 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 X 12
   feet 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 check-out 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 (wearing
   civilian clothes only) visited the Flight Simulator during USAF
   checkout and acceptance trials at Link's upper New York state
   facilities, they were surprised to park in front of a busy, active
   grocery store and then be escorted quietly to a side door that led them
   into a hidden, rear portion of the building that was Link's highly
   classified "Skunkworks" type facility for the Blackbird program. Total
   secrecy was so complete that no one in the New York township site was
   aware of what was going on behind the busy checkout stands selling
   food-stuffs and beverages.

   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 often then 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 on Love Field Airport in Dallas,Texas
   (www.flightmuseum.com) and with support from the Museum and Link (now,
   L-3 Communications Simulation and Training Division) it is intended to
   be available for viewing by Museum visitors.

Myth and lore

   The plane developed a small cult following, given its design,
   specifications, and the aura of secrecy that surrounded it. Some
   conspiracy theorists speculated that the true operational capabilities
   of the SR-71 and the associated A-12 were never revealed. Most aviation
   buffs speculate that given a confluence of structural and aerodynamic
   tolerances, the plane could fly at a maximum of Mach 3.3 for extended
   periods, and could not exceed Mach 3.44 in any currently known
   configuration. Specifically, these groups cite the specific maximum
   temperature for the compressor inlet of 427 °C (800 °F). This
   temperature is quickly surpassed at speeds greater than Mach 3.3. Mach
   3.44 is given as the speed at which the engine enters a state of
   "unstart". Some speculate that the former condition can be alleviated
   by superior compressor design and composition, while the latter might
   be solved with improved shock cones. It is known that the J58 engines
   were most efficient at around Mach 3, and this was the Blackbird's
   typical cruising speed.

   The SR-71's Pratt & Whitney J58 engines never exceeded testbench values
   above Mach 3.6 in unclassified tests. Given the history of the plane,
   the advanced and classified nature of much of its original design, and
   most importantly, the fact that no SR-71 exists in a form that is
   immediately airworthy, it may never be known what the true design
   tolerances of the aircraft were, or if these tolerances were ever
   approached in flight. This undoubtedly contributes to the mystique of
   the SR-71.

   The SR-71 was the first operational aircraft designed around a stealthy
   shape and materials. The most visible marks of its low radar cross
   section (RCS) are its inwardly-canted vertical stabilizers and the
   fuselage chines. Comparably, a plane of the SR-71's size should
   generate a radar image the size of a flying barn, but its actual return
   is more like that of a single door. Though with a much smaller RCS than
   expected for a plane of its size, it was still easily detected, because
   the exhaust stream would return its own radar signature. Furthermore,
   this is no comparison to the later F-117, whose RCS is on the order of
   a small ball bearing.

Why stricken and possible successors

   Much speculation exists regarding a replacement aircraft for the SR-71,
   most notably an aircraft identified as the Lockheed Aurora. The fact
   that the SR-71 was still able to perform its duties with an excellent
   service record at the time of its retirement, that the need for its
   reconnaissance duties had not subsided at the time of its retirement,
   and that it was retired then pressed back into active service for a
   short time before being quickly retired again, give credibility to the
   rumors of a successor aircraft. Whether that aircraft is the Lockheed
   SR-91 Aurora is still unknown to the general public, but in light of
   recent developments in the Middle East since the SR-71 was retired in
   1998, a successor aircraft in operation seems likely.

   Such a successor may be linked to a classified project rumored to exist
   at the Lockheed Skunk Works in the early 1980s to build a hybrid scram
   jet powered reconnaissance aircraft capable of speeds near Mach 5.
   Production of the aircraft may have been incorporated into the 1988
   Department of Defense budget, with the aircraft becoming operational
   around 1989. The fact that none of the systems suggested as
   replacements for the SR-71 are capable of effectively fulfilling the
   SR-71 duties, with regard to time sensitive reconnaissance and
   penetration of highly defended areas, gives additional weight to the
   existence of an undisclosed replacement. It is also possible that the
   SR-71 was retired due to shift from spy planes to low-speed " stealthy"
   unmanned aerial vehicles (popularly known as "drones") and a reliance
   on reconnaissance satellite.

Specifications (SR-71A)

   Orthographically projected diagram of the SR-71A Blackbird.

General characteristics

     * Crew: 2
     * Payload: 3,500 lb (1,600 kg) of sensors
     * Length: 107 ft 5 in (32.74 m)
     * Wingspan: 55 ft 7 in (16.94 m)
     * Height: 18 ft 6 in (5.64 m)
     * Wing area: 1,800 ft² (170 m²)
     * Empty weight: 67,500 lb (30 600 kg)
     * Loaded weight: 170,000 lb (77 000 kg)
     * Max takeoff weight: 172,000 lb (78 000 kg)
     * Powerplant: 2× Pratt & Whitney J58-1 continuous-bleed afterburning
       turbojets, 32,500 lb[f] (145 kN) each
     * Wheel track: 16 ft 8 in (5.08 m)

     * Wheel base: 37 ft 10 in (11.53 m)
     * Aspect ratio: 1.7

Performance

     * Maximum speed: Mach 3.3+ (2,200+ mph, 3530+ km/h) at 80,000 ft
       (24,000m)
     * Range:
          + Combat: 2,900 nm (5400 km)
          + Ferry: 3,200 nm (5,925 km)
     * Service ceiling: 85,000 ft (25,900m, 16 miles)
     * Rate of climb: 11,810 ft/min (60 m/s)
     * Wing loading: 94 lb/ft² (460 kg/m²)
     * Thrust/weight: 0.382

SR-71 aircraft on display

   Places to see a Blackbird on display include:
     * Air Force Armament Museum, Eglin Air Force Base, Florida
     * Air Force Flight Test Centre Museum, Edwards Air Force Base,
       California
     * Air Force Plant 42 Production Flight Test Installation, Palmdale,
       California
     * American Air Museum in Britain at the Imperial War Museum, Duxford,
       Cambridgeshire, England (the only example displayed outside the US)
     * Barksdale Air Force Base, Bossier City, Louisiana
     * Battleship Memorial Park, Mobile, Alabama (actually an A-12)
     * Beale Air Force Base, Marysville, California
     * California Science Centre in Los Angeles, California (Two-canopied
       A-12 trainer model)
     * Castle Air Museum, Atwater, California
     * Evergreen Aviation Museum, McMinnville, Oregon
     * Hill Air Force Base Museum, Ogden, Utah
     * Intrepid Sea-Air-Space Museum, New York, New York (actually an
       A-12)
     * Kalamazoo Aviation History Museum, Kalamazoo, Michigan
     * Kansas Cosmosphere and Space Centre in Hutchinson, Kansas
     * Lackland Air Force Base, San Antonio, Texas
     * March Field Air Museum, Riverside, California
     * Minnesota Air Guard Museum, Bloomington, Minnesota (Twin Cities
       International Airport) (A-12)
     * Museum of Aviation, Warner Robins, Georgia
     * Museum of Flight in Seattle, Washington (the only surviving MD-21)
     * National Museum of the United States Air Force at Wright-Patterson
       Air Force Base, near Dayton, Ohio (an SR-71, YF-12A and D-21B
       drone)
     * Pima Air & Space Museum, Tucson, Arizona
     * San Diego Aerospace Museum in San Diego, California (actually an
       A-12)
     * Southern Museum of Flight in Birmingham, Alabama (actually an A-12
       on loan from National Museum of the United States Air Force)
     * Steven F. Udvar-Hazy Centre, at Washington Dulles International
       Airport in Chantilly, Virginia
     * Strategic Air and Space Museum in Ashland, Nebraska
     * U.S. Space & Rocket Centre, Huntsville, Alabama (actually an A-12)
     * Virginia Aviation Museum in Richmond, Virginia

   Imperial war museum, Duxford, at Duxford, Cambridge, United Kingdom
   (the only SR-71A on display outside the U.S

   See also External links below

Other images

   M/D-21 Blackbird

   SR-71 Blackbird at Steven F. Udvar-Hazy Centre

   SR-71 Blackbird at Steven F. Udvar-Hazy Centre

   Blackbird at the Strategic Air and Space Museum in Ashland, Nebraska

   SR-71 and D-21B at the Pima Air & Space Museum

Popular culture

     * The Tom Clancy novel The Cardinal of the Kremlin mentions the SR-71
       as a test tracking target for an experimental anti-ballistic
       missile defense system ( SDI, or less formally, "Star Wars").
     * The Tom Clancy Novel Red Storm Rising mentions the SR-71 as a
       possible NATO candidate to photograph the Andøya Air Station due to
       the heavy concentration of Soviet/ Warsaw Pact fighter jets and
       anti-aircraft missile sites north of Bodø.
     * In Manga Science (まんがサイエンス 1), a science teaching comic short
       series, volume 2, an SR-71 was used to demonstrate the heat
       generated in high speed flight.
     * A modified Blackbird is the primary mode of transport for the
       superhero team the X-Men. (See Blackbird (comics) for further
       details.)
     * In the Manga Hellsing, the vampire Alucard uses a British-modified
       SR-71 to kamikaze into an enemy aircraft carrier and to take
       control of the ship.
     * In the 1985 movie D.A.R.Y.L., the main character -- a
       pre-teen-looking cyborg -- steals and flies an SR-71 to elude the
       government and return to the family with which he lived.
     * In Jeremy Clarksons book " I Know You Got Soul", he mentions the
       SR-71 as a machine with soul.
     * The aircraft appears in Metal Gear Solid 3: Snake Eater, as a hub
       to launch a manned D-21 infiltration drone.
     * It also appears in Dan Browns novel, Angels and Demons

Related content

Related development

     * A-12 Oxcart
     * Lockheed YF-12
     * M-21 drone

Comparable aircraft

     * Bristol 188
     * Tsybin NM-1/RSR Project

Designation sequence

   XB-68/ SM-68 I/ SM-68 II - RB-69 -  XB-70 - SR-71
                                       IM-70 - GAM-71 - XGAM-72 - SM-73 - SM-75
   Retrieved from " http://en.wikipedia.org/wiki/SR-71_Blackbird"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
