fas: The McDonnell Douglas F/A-18 Hornet traces its direct ancestry to the Northrop Cobra, a twin engine multimission fighter design developed for the export market in the late 1960s. In the early 1970s the Air Force pressed for development of a new generation of lightweight fighters-single-seat jet aircraft "optimized" for agility and air combat maneuvering, with high thrust-to-weight ratios (above 1 to 1), and good acceleration. Out of this interest came the so-called "Lightweight Fighter" program. In January 1972, the Lightweight Fighter Program solicited design specifications from several American manufacturers. Participants were told to tailor their specifications toward the goal of developing a true air superiority lightweight fighter. General Dynamics and Northrop were asked to build prototypes, which could be evaluated with no promise of a follow-on production contract. These were to be strictly technology demonstrators. The two contractors were given creative freedom to build their own vision of a lightweight air superiority fighter, with only a limited number of specified performance goals. Northrop's entry was derived from the Cobra design. Northrop produced the twin-engine YF-17 using breakthrough aerodynamic technologies and two high-thrust General Electric YJ101 engines. General Dynamics countered with the compact YF-16, built around a single F100 engine.