АҚШ әскери авиациясы үшін жасалған прототиптік истребитель ұшағы

Prototype fighter aircraft for the US military

The Northrop YF 17 (nicknamed "Cobra") was a prototype lightweight fighter aircraft designed by Northrop aviation for the United States Air Force's Lightweight Fighter (LWF) technology evaluation program. The LWF was initiated because many in the fighter community believed that aircraft like the F 15 Eagle were too large and expensive for many combat roles. The YF 17 was the culmination of a long line of Northrop designs, beginning with the N 102 Fang in 1956, continuing through the F 5 family. 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. 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 and weight to the F 15 and ultimately replaced the F 14. A non naval, export variant developed and marketed by Northrop, the F 18L failed to attract buyers; nevertheless, many air forces have operated the McDonnell Douglas F/A 18 as a purely land based fighter.

The aircraft's main design elements date to early 1965, from the internal Northrop project N 300. The N 300 was derived from the F 5E, and features a longer fuselage, small leading edge root extensions (LERX), and more powerful GE15 J1A1 turbojets, rated at 9,000 lbf (40 kN). The wing position was raised slightly to increase ground clearance for ordnance. The N 300 further evolved into the P 530 Cobra, which uses GE15 J1A5 engines, with a very small 0.25:1 bypass ratio leading to the nickname "leaky turbojet". The bypass air was required for cooling the afterburner and nozzle and the cool bypass duct surface allowed the engine bay to be constructed of lighter, cheaper materials. The aircraft was powered by two General Electric YJ101 GE 100 afterburning turbojets, installed next to each other to minimize thrust asymmetry in the event of an engine failure. To minimise engine removal time they were removed from below the aircraft without disturbing the empennage controls. Each engine drove an hydraulic pump for independent aircraft systems. Unlike the P 530, the YF 17 had partial fly by wire, called an electronic control augmentation system (ECAS), which used ailerons, rudders, and stabilators for primary flight control. flying for 61 minutes reaching an altitude of 18,000 feet and a maximum speed of 610 miles per hour. Chouteau afterwards remarked that, "When our designers said that in the YF 17 they were going to give the airplane back to the pilot, they meant it. It's a fighter pilot's fighter."

Initially, the U. S. Navy was not heavily involved as a participant in the LWF program. In August 1974, Congress directed the Navy to make maximum use of the technology and hardware of the LWF for its new lightweight strike fighter, the VFAX. As neither contractor had experience with naval fighters, they sought partners to provide that expertise. General Dynamics teamed with Vought for the Vought Model 1600; Northrop with McDonnell Douglas for the F 18. Each submitted revised designs in line with the Navy needs for a long range radar and multirole capabilities.

Prototype YF 17 72 1569 was sent to NASA's Dryden Research Center for base drag studies from 27 May to 14 July 1976 prior to the first F/A 18 prototype under development.