The first flight of Northrop YF-17 “Cobra” experimental lightweight fighter is made. It is built to test what might be called the aerodynamics of agility, with all of the factors of weight, materials, and design geared to making it as agile as possible…(1)
When the Lightweight Fighter program was announced in 1971, Northrop modified the P-530 into the P-600 design that would be designated YF-17A. Whereas the P-530 was intended as a multi-role aircraft, the P-600 was to be strictly an air-to-air demonstrator, and consequently, the cannon moved from the underside of the fuselage to the upper part. Design of the YF-17 and the prototype YJ101 engine, a development of the GE15 engine, consumed over a million man-hours, and 5,000 hours of wind tunnel testing.
Although it lost the LWF competition to the F-16 Fighting Falcon, the YF-17 was selected for the new Naval Fighter Attack Experimental (VFAX) program. In enlarged form, the F/A-18 Hornet was adopted by the United States Navy and United States Marine Corps to replace the A-7 Corsair II and F-4 Phantom II, complementing the more expensive F-14 Tomcat.[1] This design, conceived as a small and lightweight fighter, was scaled up to the Boeing F/A-18E/F Super Hornet, which is similar in size to the original F-15.”
Source: (1) Skytamer.com; (2)Wikipedia