Air Plane Photos 2013: Fastest Airplane

Fastest Airplane

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The Lockheed SR-71 "Blackbird" was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft.[1] It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by Lockheed and its Skunk Works division. 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, the standard evasive action was simply to accelerate and outfly the missile.[2]

The SR-71 served with the U.S. Air Force from 1964 to 1998. A total of 32 aircraft were built; 12 were lost in accidents, and none lost to enemy action.[3][4] The SR-71 has been given several nicknames, including Blackbird and Habu.[5] Since 1976, it has held the world record for the fastest air-breathing manned aircraft, a record previously held by the

Lockheed's previous reconnaissance aircraft was the relatively slow U-2, designed for the Central Intelligence Agency (CIA). The 1960 downing of Francis Gary Powers's U-2 underscored the aircraft's vulnerability and the need for faster reconnaissance aircraft. The CIA turned again to Kelly Johnson and Lockheed's Skunk Works, who developed the A-12[9] and would go on to build upon its design concepts for the SR-71.

The A-12 first flew at Groom Lake (Area 51), Nevada, on 25 April 1962. Thirteen were built; two variants were also developed, including three YF-12A interceptor prototypes, and two M-21 drone carrier variants. The aircraft was meant to be powered by the Pratt & Whitney J58 engine, but development ran over schedule, and it was equipped instead with the less powerful Pratt & Whitney J75. The J58s were retrofitted as they became available, and became the standard powerplant for all subsequent aircraft in the series (A-12, YF-12, M-21) as well as the SR-71. The A-12 flew missions over Vietnam and North Korea before its retirement in 1968. The program's cancellation was announced on 28 December 1966,[10] due both to budget concerns[11] and because of the forthcoming SR

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.[12] Originally named R-12[N 1] by Lockheed, the Air Force version was longer and heavier than the A-12, with a longer fuselage to hold more fuel, two seats in the cockpit, and reshaped chines. Reconnaissance equipment included signals intelligence sensors, a side-looking radar and a photo camera.[12] The CIA's A-12 was a better photo reconnaissance platform than the Air Force's R-12, since the A-12 flew somewhat higher and faster,[11] and with only one pilot it had room to carry a superior camera[11] and more instruments.[13]

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 the Air Force reconnaissance model since July 1964. 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][N 2]

In 1968, Secretary of Defense Robert McNamara canceled the F-12 interceptor program; the specialized tooling used to manufacture both the YF-12 and the SR-71 was also ordered destroyed.[16] Production of the SR-71 totaled 32 aircraft with 29 SR-71As, 2 SR-71Bs, and the single SR-71C.[17]

The SR-71 was designed for flight at over Mach 3 with a flight crew of two in tandem cockpits, with the pilot in the forward cockpit and the Reconnaissance Systems Officer (RSO) monitoring the surveillance systems and equipment from the behind cockpit.[18] The SR-71 was designed to minimize its radar cross-section, an early attempt at stealth design.[19] Finished aircraft were painted a dark blue, almost black, to increase the emission of internal heat and to act as camouflage against the night sky. The dark color led to the aircraft's call sign "Blackbird".

On most aircraft, use of titanium was limited by the costs involved in procurement and manufacture. It was generally used only in components exposed to the highest temperatures, such as exhaust fairings and the leading edges of wings. On the SR-71, titanium was used for 85% of the structure, with much of the rest polymer composite materials.[20] To control costs, Lockheed used a more easily worked alloy of titanium which softened at a lower temperature.[N 3]

The challenges posed by the SR-71 led Lockheed to develop entirely new fabrication methods to enable its manufacture, and have since been used in the manufacture of many other aircraft. Welding the titanium requires distilled water, as the chlorine present in tap water is corrosive; commonplace cadmium-plated tools could not be used as they also caused corrosion.[21] Metallurgical contamination was another problem; at one point 80% of the delivered titanium for manufacture was rejected on these grounds.[22][23]

A Lockheed M-21 with D-21 drone on top

The high temperatures generated during flight required special design and operating techniques. For example, major portions of the skin of the inboard wings were corrugated, not smooth. (Aerodynamicists initially opposed the concept and accused the design engineers of trying to make a Mach-3 variant of the 1920s-era Ford Trimotor, known for its corrugated aluminum skin.[24]) The heat of flight would have caused a smooth skin to split or curl, but the corrugated skin could expand vertically and horizontally. The corrugation also increased longitudinal strength. Similarly, the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was achieved only when the airframe heated up and expanded 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 on the runway. At the beginning of each mission, the aircraft would make a short sprint after takeoff to warm up the airframe, then refuel before heading off to its destination.

Cooling was carried out by cycling fuel behind the titanium surfaces in the chines. On landing, the canopy temperature was over 300 °C (572 °F).[24] The red stripes on some SR-71s were to prevent maintenance workers from damaging the skin.

The first operational aircraft designed around a stealthy shape and materials, the SR-71 had several features designed to reduce its radar signature. The SR-71 had a radar cross section (RCS) of around 10 square meters,[25] much greater than the later Lockheed F-117 Nighthawk, which had an RCS equivalent in size to a ball bearing.[26] Drawing on the first studies in radar stealth technology, which indicated that a shape with flattened, tapering sides would reflect most radar energy away from the radar beams' place of origin, engineers added chines and canted the vertical control surfaces inward. Special radar-absorbing materials were incorporated into sawtooth-shaped sections of the aircraft's skin. Cesium-based substances were added to the fuel to somewhat reduce the visibility of the exhaust plumes to radar, although the large and hot exhaust stream produced at speed remained quite apparent. For all this effort, Kelly Johnson later conceded that Soviet radar technology advanced faster than the stealth technology employed against it.[27]

The SR-71 carried electronic countermeasures, but its greatest protection was its high speed and cruising altitude that made it almost invulnerable to the weapons of its day. Merely accelerating would typically be enough to evade a surface-to-air missile,[2] and the plane was faster than the Soviet Union's principal interceptor, the MiG-25.[28] In its service life, no SR-71 was shot down, despite many attempts to do so.[citation needed]