It was the first operational aircraft to be designed with stealth technology. Work on what would become the F commenced in the s as a means of countering increasingly sophisticated Soviet surface-to-air missiles SAMs.
On 1 November , Lockheed decided to proceed with the F development program. A total of five prototypes were produced; the first of which performed its maiden flight in at Groom Lake, Nevada. The first production F was delivered in , and its initial operating capability was achieved in October The aircraft's faceted shape made from two-dimensional flat surfaces heavily contributes to its relatively low radar cross-section of about 0. To minimize its infrared signature , it has a non-circular tail pipe that mixes hot exhaust with cool ambient air and lacks afterburners ; it is also restricted to subsonic speeds as breaking the sound barrier would produce an obvious sonic boom that would increase both its acoustic and infrared footprints.
While its performance in air combat maneuvering was less than that of most contemporary fighters, it was strictly an attack aircraft despite being commonly referred to as the "Stealth Fighter". It is aerodynamically unstable in all three aircraft principal axes and thus requires constant flight corrections via a fly-by-wire FBW flight system to maintain controlled flight. Even in the years following its entry to service, the F was a black project , its existence being denied by USAF officials.
On 10 November , the F was publicly acknowledged for the first time. Its first combat mission was flown during the United States invasion of Panama in The last of 59 production Fs were delivered on 3 July The F was widely publicized for its role in the Gulf War of , having flown around 1, sorties and scored direct hits on what the US military described as 1, high-value targets in Iraq.
Fs also participated in the conflict in Yugoslavia , during which one was shot down by a SAM in In , Robert Watson Watt , a British engineer who invented radar , noted that measures to reduce an object's radar cross-section RCS could be used to evade radar detection. The obvious and logical conclusion was that even a large aircraft could reduce its radar signature by exploiting this principle.
