02/28/2011. Remarks by Johan Visschedijk: "The YF-17 was a twin-engined fighter prototype developed to demonstrate advanced technology applicable to air combat. Distinguishing features included mid-wing configuration, a moderately-swept wing, highly-swept leading edge root extensions, underwing intakes and twin vertical fins. Extensive use was made of graphite composite materials in the aircraft's structure, to the extent that approximately 10%, by weight, was composed of such material.

Design of Northrop's lightweight fighter began in May 1966, and construction of two prototypes started in early 1973, following the award of a contract by the USAF. The first prototype (s/n 72-1569 c/n 1) was rolled out on April 4, 1974 and flew for the first time on June 9, 1974; the second (s/n 72-1570 c/n 2) made its first flight on August 21, 1974.

Evaluation in competition with the General Dynamics YF-16 prototypes resulted in USAF selection of the latter aircraft for production as an operational air combat fighter. Subsequent evaluation by the US Navy led to the teaming of Northrop with McDonnell Douglas to develop a new air combat fighter for the Navy. Evolved from the YF-17 the new aircraft, designated
F/A-18, was much heavier to strengthen it for carrier operations.

With Navy markings and initially labeled "F-18 Prototype" (later as "F/A-18 Prototype"), the second YF-17 was extensively used as demonstrator and for development work for the McDonnell Douglas F/A-18 Hornet program; the true F/A-18A first flew in 1978. Presently the second YF-17 is preserved at the USS Alabama Battleship Memorial Park in Mobile, Alabama."