DARPA’s Stealth Revolution

In the early 1970s, a study by DARPA brought to light the extent of the vulnerabilities of U.S. aircraft and their on-board equipment to detection and attack by our adversaries.

lnerabilities of U.S. aircraft and their on-board equipment to detection and attack by our adversaries. Based on the study and encouragement from Office of the Secretary of Defense and others, DARPA embarked on a program to develop the technologies for stealthy aircraft. Under a code word program, “HAVE BLUE,” two aircraft were built, and first flight occurred successfully in April 1977. Technologies addressed by DARPA included the reduction of radar cross section through a combination of shaping to form a limited number of radar return spikes designed to be less detectable by ground-based radars, radar absorbent materials, infrared shielding, heat dissipation, reduced visual signatures, low-probability-of-intercept (LPI) radar, active signature cancellation, and inlet shielding, exhaust cooling and shaping, and windshield coatings.

In November 1978, the Air Force initiated a program for the F-117 based on the HAVE BLUE demonstrations and the DARPA-developed technologies. First flight of the F-117 was in June 1981 and the aircraft became operational in October 1983. A total of 59 aircraft were built, and 36 were deployed to Saudi Arabia in late 1990, from which they were highly successful in F-117 Nighthawks attacks against high-value Iraqi targets. In the Desert Storm operation, the Air Force flew F-117s on 1,271 sorties without a single aircraft loss, successfully penetrating air defenses, and delivering 2,000 tons of ordnance to account for some 40% of all targets with an 80%-85% hit rate.