F117 nighthawk-the first stealth aircraft

The Lockheed F-117 Nighthawk is a single-seat, twin-engine stealth attack aircraft that was developed by Lockheed's secretive Skunk Works division and operated by the United States Air Force (USAF). The F-117 was based on the Have Blue technology demonstrator, and was the first operational aircraft to be designed around stealth technology. The maiden flight of the Nighthawk took place in 1981 and the aircraft achieved initial operating capability status in 1983. The Nighthawk was shrouded in secrecy until it was revealed in 1988

The F-117's unusual design surprised and puzzled experienced pilots; a Royal Air Force pilot who flew it as an exchange officer while still secret stated that when he first saw a photograph of the F-117, he "promptly giggled and thought to myself 'this clearly can't fly'".Early stealth aircraft were designed with a focus on minimal radar cross-section (RCS) rather than aerodynamic performance. Highly-stealth aircraft like the F-117 Nighthawk are aerodynamically unstable in all three Aircraft principal axes and require constant flight corrections from a fly-by-wire (FBW) flight system to maintain controlled flight.It is shaped to deflect radar signals and is about the size of an F-15 Eagle. The single-seat Nighthawk is powered by two non-afterburning General Electric F404 turbofan engines. It is air refuelable and features a V-tail.

The F-117 has a Radar cross-section of about 0.001 m2 (0.0108 sq ft). Among the penalties for stealth are lower engine thrust, due to losses in the inlet and outlet, a very low wing aspect ratio, and a high sweep angle (50°) needed to deflect incoming radar waves to the sides.With these design considerations and no afterburner, the F-117 is limited to subsonic speeds. The F-117A carries no radar, which lowers emissions and cross-section, and whether it carries any radar detection equipment is classified.

The F-117A's faceted shape (made from 2-dimensional flat surfaces) resulted from the limitations of the 1970s-era computer technology used to calculate its radar cross-section. Later supercomputers made it possible for subsequent planes like the B-2 bomber to use curved surfaces while staying stealthy, through the use of far more computational resources to do the additional calculations needed.An exhaust plume contributes a significant infrared signature. The F-117 reduces IR signature with a non-circular tail pipe (a slit shape) to minimize the exhaust cross-sectional volume and maximize the mixing of hot exhaust with cool ambient air. The F-117 lacks afterburners, because the hot exhaust would increase the infrared signature, and breaking the sound barrier would produce an obvious sonic boom, as well as surface heating of the aircraft skin which also increased the infrared footprint.

As a result, its performance in air combat maneuvering required in a dogfight would never match that of a dedicated fighter aircraft. This was unimportant in the case of this aircraft since it was designed to be a bomber. Passive (multistatic) radar, bistatic radar and especially multistatic radar systems detect some stealth aircraft better than conventional monostatic radars, since first-generation stealth technology (such as the F-117) reflects energy away from the transmitter's line of sight, effectively increasing the radar cross section (RCS) in other directions, which the passive radars monitor.
compiled by XENOCIDE