Saturday, 23 February 2013

Future Fighter Jets

Future Fighter Jets Biography

In 1964, Pyotr Ufimtsev, a Soviet mathematician, published a seminal paper titled Method of Edge Waves in the Physical Theory of Diffraction in the journal of the Moscow Institute for Radio Engineering, in which he showed that the strength of a radar return is related to the edge configuration of an object, not its size.[7] Ufimtsev was extending theoretical work published by the German physicist Arnold Sommerfeld.[8][9][10] Ufimtsev demonstrated that he could calculate the radar cross-section across a wing's surface and along its edge. The obvious and logical conclusion was that even a large aircraft could be made stealthy by exploiting this principle. However, the airplane's design would make it aerodynamically unstable, and the state of computer technology in the early 1960s could not provide the kinds of flight computers which allow aircraft such as the F-117, and B-2 Spirit to stay airborne. However, by the 1970s, when Lockheed analyst Denys Overholser found Ufimtsev's paper, computers and software had advanced significantly, and the stage was set for the development of a stealthy airplane.[11]
F-117A painted in "Gray Dragon" experimental camouflage scheme.
The F-117 was born after combat experience in the Vietnam War when increasingly sophisticated Soviet surface-to-air missiles (SAMs) downed heavy bombers.[12] It was a black project, an ultra-secret program for much of its life, until the late 1980s.[13] The project began in 1975 with a model called the "Hopeless Diamond"[14][15] (a wordplay on the Hope Diamond because of its appearance). The following year, the Defense Advanced Research Projects Agency issued Lockheed Skunk Works a contract to build and test two Stealth Strike Fighters, under the code name "Have Blue".[16] These subscale aircraft incorporated jet engines of the Northrop T-38A, fly-by-wire systems of the F-16, landing gear of the A-10, and environmental systems of the C-130.[16] By bringing together existing technology and components, Lockheed built two demonstrators under budget, at $35 million for both aircraft, and in record time.[16]
The maiden flight of the demonstrators occurred on 1 December 1977.[17] Although both aircraft were lost during the demonstration program, test data proved positive. The success of Have Blue led the government to increase funding for stealth technology. Much of that increase was allocated towards the production of an operational stealth aircraft, the Lockheed F-117A, under the program code name "Senior Trend".[18][19]The decision to produce the F-117A was made on 1 November 1978, and a contract was awarded to Lockheed Advanced Development Projects, popularly known as the Skunk Works, in Burbank, California.[20] The program was led by Ben Rich, who called on Bill Schroeder, a Lockheed mathematician, and Denys Overholser, a computer scientist, to exploit Ufimtsev's work. The three designed a computer program called "Echo", which made it possible to design an airplane with flat panels, called facets, which were arranged so as to scatter over 99% of a radar's signal energy "painting" the aircraft.[11][21][22]
The first YF-117A, serial number 79-0780, made its maiden flight from Groom Lake, Nevada on 18 June 1981,[23] only 31 months after the full-scale development decision. The first production F-117A was delivered in 1982, and operational capability was achieved in October 1983.[8][24] The Air Force denied the existence of the aircraft until 1988, when a grainy photograph was released to the public. In April 1990 two were flown into Nellis Air Force Base, Nevada, arriving during daylight and publicly displayed to a crowd of tens of thousands. Quote: "Shortly after I arrived in Las Vegas to work at the Dunes, the USAF announced a static display of two aircraft for a one day open house at Nellis AFB."[25] Five Full Scale Development (FSD) aircraft were built, designated "YF-117A".[26] The last of 59 production F-117s were delivered on 3 July 1990.[24][27]
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