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SR-71 Black bird
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The LockheedSR-71 "Blackbird" was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft. It was developed from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed Skunk Works as a black project. 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 launch was detected, standard evasive action was simply to accelerate.

The SR-71 was in service with the U.S. Air Force from 1964 to 1998. Twelve of the 32 aircraft were destroyed in accidents; none were lost to enemy action. The SR-71 was unofficially named the Blackbird, and called the Habu 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.

Background

The Lockheed A-12, designed for the Central Intelligence Agency (CIA) by Clarence Johnson at the Lockheed Skunk Works,[9] was the precursor of the SR-71. The A-12's first flight took place at Groom Lake (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. 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 interceptor prototypes, and two M-21 drone carrier variants. The cancellation of A-12 program was announced on 28 December 1966,[10] due to budget concerns,[11] 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. 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 ****pit, 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 repeatedly criticized President Lyndon B. Johnson and his administration for falling behind the Soviet Union in developing new weapons. Johnson decided to counter this criticism by revealing the existence of the YF-12A Air Force interceptor (which also served as cover for the still-secret A-12)[14] and, on 25 July 1964, the Air Force reconnaissance model. Air Force Chief of Staff General Curtis LeMay preferred the SR (Strategic Reconnaissance) designation and wanted the RS-71 to be named SR-71. Before the July speech, LeMay lobbied to modify Johnson's speech to read SR-71 instead of RS-71. The media transcript given to 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.[15][16]

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,[N 2] 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 and operational details

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, and the energy generated by this heats the airframe. To address this problem, high-temperature materials were needed, and the airframe of the SR-71 was substantially made of titanium, obtained from the USSR at the height of the Cold War. 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 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 night sky. The aircraft was designed to minimize its radar cross-section, an early attempt at stealth design. The call sign of the aircraft, "Blackbird", signifies the resistance of its airframe to visible light and radar detection.

The air inlets allowed the plane to cruise at over Mach 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 moved the spike as much as 26 inches (66 cm) to the rear.[18]

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, riding on it closer to the inlet cowling until it just touched slightly inside the cowling lip. In this position shock-wave spillage, causing turbulence over the outer nacelle 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 and provides up to 70% of the aircraft's thrust at higher mach numbers.

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).[20] 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, 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.[21]

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 ****pit canopies until the initial unstart motions subsided.[22]

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.[23] Lockheed implemented an electronic control to detect unstart conditions and perform this action without pilot intervention.[24] 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.

Titanium structures and airframe

Before the Blackbird, titanium was only used in high-temperature exhaust fairings and other small parts directly related to supporting, cooling, or shaping high-temperature areas on aircraft. Building the Blackbird's structure using 85% titanium and 15% composite materials was a first in the aircraft industry. The advances made by Lockheed in fabricating this material have been used in subsequent high-speed aircraft, including most modern fighters.

Titanium was difficult to work with, expensive, and scarce. Initially, 80% of the titanium delivered to Lockheed was rejected due to metallurgical contamination. One example of the difficulties of working with titanium is that welds made at certain times of the year were more durable than welds made at other times. It was found that the manufacturing plant's water came from one reservoir in the summer and another in the winter; the slight differences in the impurities in the water from these sources led to differences in the durability of the welds, since water was used to cool the titanium welds.

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 (heat treatment).

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  known for its corrugated aluminum skin  go Mach 3. The red stripes on some SR-71s are to prevent maintenance workers from 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 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 with high heat tolerance was used in high-temperature areas.

 Stealth

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 signature. The first studies in radar stealth technology 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-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 (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 signature when cruising at Mach 3.2 or more. It was visible on air traffic control radar for hundreds of miles, even when not using its transponder. SR-71s were evidently detected by radar, as missiles were often fired at them.

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, not one was shot down, despite over 4,000 attempts to do so. All the pilot had to do was to accelerate.

 

Crews flying the SR-71 at 80,000 ft (24,000 m) faced two main survival problems: maintaining consciousness at high altitude, and surviving ejection. With a standard pressure demand oxygen mask, human lungs cannot absorb oxygen quickly enough above 43,000 ft (13,000 m). The pressure difference inside the mask versus the ****pit 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 (230 °C) as a result of the air flow. To solve these problems, the David Clark Company was hired to produce protective full pressure suits for the A-12, YF-12, MD-21 and SR-71 aircraft. These suits were later adapted for use on the Space Shuttle.

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 (120 °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 ****pit 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 15,000 ft (4,600 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 78,000 ft (24,000 m) or higher while chamber heaters would be turned on to 450 °F (230 °C), gradually decreasing at the expected rate in real life free-fall.

The cabin could be pressurized to an altitude of 10,000 ft (3,000 m) or 26,000 ft (7,900 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 flying suits, or a full pressure suit.

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

The Pratt & Whitney J58-P4 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 (145 kN) of static thrust.

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. 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.

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 (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 missile. With this background, Nortronics developed the Astro-Inertial Navigation System for the AGM-48 Skybolt 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 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 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 ****pit 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'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 83,000 feet (25,000 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 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 (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 80,000 feet (24,000 m), it could survey 100,000 square miles (260,000 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 2,000 nmi (3,700 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 in Palmdale, California. 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 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 Airbase, 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 and Major Edward D. Payne flew the first operational SR-71 sortie 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; Kadena Air Base, Okinawa, Japan; and RAF Mildenhall, England. The aircraft was flown to the National Museum of the United States Air Force near Dayton, Ohio 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 (as did the A-12s preceding them) after a pit viper indigenous to Japan, which the Okinawans thought the plane resembled.[5]

Swedish JA 37 Viggen fighter pilots, using the predictable patterns of SR-71 routine flights over the Baltic Sea, 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 to occur was the thin stretch of international airspace between Öland and Gotland 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, 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 and upgrades to the B-52 Stratofortress, 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 (unlike the Lockheed U-2) 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 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., 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.





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Veteran Member - Level 1

Posts: 59
Date: Apr 11, 2011
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Thanks for the info.



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Date: Apr 17, 2011
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A-12 Blackbird

http://www.sr-71.org/blackbird/a-12/

The A-12 is the forerunner of the SR-71 and has nearly the same shape and dimensions as its replacement. Designed to replace the U-2, the A-12 flew higher and four times as fast to outrun enemy defenses and gather intelligence. The A-12 is primarily an over flight vehicle unlike the SR-71. Its major advantages in capabilities to the SR-71 include its higher-resolution photography and its ability to go marginally faster (Mach 3.3) than the SR-71. However, the SR-71 was chosen as successor to the A-12 due to its side-looking radar and cameras, allowing it to gather important reconnaissance data without penetrating enemy airspace.

YF-12 Blackbird

http://www.sr-71.org/blackbird/yf-12/

The YF-12A is a concept aircraft for a mach 3+ bomber/interceptor that provided a strong deterrent against world aggressors. In order to protect North America, 93 production F-12Bs needed to be built. However, the program was cancelled in the mid-1960s for budgetary reasons. Also, the Strategic Air Command (SAC) may have felt that the YF-12 would threaten the development of their other supersonic bomber, the XB-70 Valkyrie.

SR-71 Blackbird

http://www.sr-71.org/blackbird/sr-71/

Unofficially, the SR-71 carried many nicknames, including the "Habu,"  "SR," "Lady in Black," and "Sled;" but most of us know the SR-71 as the "Blackbird." The SR-71 was developed as a long-range strategic reconnaissance aircraft capable of flying at speeds over Mach 3.2 and at 85,000 feet. The first SR-71 to enter service was delivered in 1966 and due to politics, it was retired in 1990. However, the USAF still kept a few SR-71s in operation up until 1998, after a few were brought back to service in 1995. NASA's DFRC at Edwards AFB, CA flew the SR-71 from 1991 until its final flight in October 1999.

M-21 Blackbird

http://www.sr-71.org/blackbird/m-21.php

The M-21 is one of the few projects at the Skunk Works that was relatively unsuccessful. The M-21 is an A-12-like aircraft designed to launch the once ultra-secret D-21 Drone. When the United States signed a treaty to end flights of manned vehicles over the Soviet Union, an unmanned vehicle was needed for reconnaissance. Since the A-12 is an overflight vehicle, it would undermine the treaty if used in the future. Consequently, after A-12 #60-6939 was built, two aircraft called M-21s were built for the TAGBOARD program.

There were two M-21 aircraft built, 60-6940 and 60-6941. Aircraft #60-6941 crashed when the aircraft collided with a D-21 during the launch. This crash ended all M-21 sorties. Later on, the B-52H was used to launch the D-21 drone. The other M-21 is on Display at the Museum of Flight in Seattle, WA.

D-21 Drone

http://www.sr-71.org/blackbird/d-21.php

Due to the agreement between the Soviet Union and the United States restricting the use of manned vehicles over the Soviet landmass, this unmanned aircraft was developed. The drone was carried and launched by two A-12-like aircrafts called M-21s, and a number of B-52Hs.

The D-21 was released at high speed, and was separated from the M-21 by the use of ballistic charges. The concept behind the drone was quite simple. It would fly over a landmass and eject the reconnaissance data before crashing, to be recovered shortly after by the Air Force. This aircraft was never used operationally, and only 38 of these drones were built.



-- Edited by Air_Gopher on Sunday 17th of April 2011 07:32:25 PM

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SR-71 Flight Manual

http://www.sr-71.org/blackbird/manual/

SR-71-6CF-1 Functional Check Flight Procedures Manual for SR-71A and SR-71B aircraft

http://www.sr-71.org/blackbird/sr-71-6cf-1/

YF-12A-1: The YF-12A Utility Flight Manual

http://www.sr-71.org/blackbird/yf-12a-1/



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Thanks Air Gopher!!



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All that was from the Blackbird Archive, good site. http://www.sr-71.org/blackbird/



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Alan Dallas


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From DefenceTalk

 

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http://www.flightglobal.com/PDFArchive/View/1993/1993%20-%202255.html?search=Grumman%20ATF%20aircraft

An attempt by design students to research a multi-role supersonic advanced tactical fighter-bomber (ATFB) development of the Blackbird.



-- Edited by Commander31 on Sunday 17th of April 2011 07:48:52 PM

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Northrop 1993 Advanced Fighter-Bomber Concept



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Commander31 wrote:

Northrop 1993 Advanced Fighter-Bomber Concept


 

And a read further at SPF and you'll find a magic linky to an informative PDF...

http://pdf.aiaa.org/preview/1993/PV1993_4010.pdf



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if they decided to go through with the bomber concept, it would have to be able to defend itself, becauase no other aircraft back then besides another SR-71 had the range to stay with it on its missions



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Here are a couple of tidbits.

A strike version of the Blackbird was looked at, design designation B-12. It looked like and SR-71 with an F-12 type nose. Among the payloads were four AGM-69 SRAM missiles in the chines. Launched from B-52s, the SRAM had a range of up to ~100 miles, depending on the profile used. Launched from the much higher speed an altitude of a Blackbird, it was estimated they'd have a range of 500 miles. Lockheed didn't push to hard for tis version because of a promise made to USAF that they wouldn't try and compete with the B-70, which USAF thought there might be a chance of reviving.

The F-12B was not canceled for budgetary reasons. Congress funded a program initially for 93 aircraft, with potential growth to over twice as many. Secretary of Defense Robert McNamara, though, wanted USAF to use his F-111 as a basis for a new interceptor, and impounded the money. When USAF showed no interest and Congress funded the program again the following year, he attempted to force the issue by ordering the production line for the Blackbird destroyed, insuring no F-12s (or any other version) could ever be built. This was not a contractual obligation, except in the sense that any contractor is required to do what ever DoD says with a production line it paid for).

Regarding the interception of SR-71s by JA-37s, it must be remembered that on those missions the SRs were required to fly through a very predictable, narrow corridor to remain out of anyone's national airspace, Teh SR would make no defensive maneuvers, which would not be the case on a "hot" mission. Nor were the full capabilities of the SR's DEF (defensive electronics) package used. There'd be no point, since everyone knew where the ac was (even if you couldn't catch it, from the Viggen's altitude you could see it by looking waaay up). In addition, turning the DEF fully on to block the Swedes could turn out to be an ELINT intelligence bonanza for the Soviets.

Although two were kept in flyable storage for a year after President Clinton killed the program, no SR-7 flew for the Air Force from the moment the Presidential line item veto (the only time it's been used in history, BTW) hit in 1997.


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First flight of the A-12 at Groom Lake narrated by its pilot, Lockheed test pilot Lou Schalk



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