The Northrop YF -17 Cobra was a prototype daytime lightweight prototype program designed for technology assessment Light Weight Fighter (LWF) of the United States Air Force. The project LWF was created because the F-15 Eagle was too big and expensive for many combat roles. The YF-17 lost the competition to the F-16 Fighting Falcon, but it was modified and enlarged to operate on Aircraft Carriers, it became the F/A-18 Hornet.