Northrop YF-17 Cobra

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 losed the competition to the F-16 Fighting Falcon, but he was modified and enlarged to operate in Aircraft Carriers, it was borned the F/A-18 Hornet.

Design and Development
The design of the main elements of the aircraft then began to early 1965, from internal program Northrop N-300. The N-300 was based on the F-5E, with an extended fuselage, small extensions on the edge (LEX) And turbojet GE15 - J1A1 40 kN of thrust each. The wings moved higher on the fuselage to increase the flexibility of the load. The N-300 evolved into the P530 Cobra, which used engines GE15-J1A5 thrust of 57.8 kN with a low -pass ratio. The bypass flow was a blast cold in the rear of the engine, getting the nickname " leaky turbojet ", which allowed engines to build the container with lighter materials and cheap.

The wing shape and the nose of the P530 was similar to the F-5 with a form of trapezoid formed by an angle of 20 degrees and a free edge angle, but doubling the wing area. The wings originally mounted at the top of the fuselage, it was gradually moving to a middle position. Its greatest features distinctive was the leading edges LEX, narrowed towards the fuselage under the cockpit. To allow for maneuvering angles of attack above 50 ° and provided 50 % more lift. The extensions were also used to smooth the airflow coming to the jacks of the engines in high angles of attack. His head looks like a cobra the plane had got his nickname, that would be adopted by the YF-17. The studies showed that a single vertical stabilizer was insufficient for high angles of attack and moved to two twins stabilized tilted 45 degrees. The result was an aircraft with improved longitudinal stability and maneuverability. However, Northrop did not trust controls fly-by-wire maintained as mechanical control systems. The plane, which was presented February 28 of 1971, Announced as a model of maximum weight 18,000 kg and maximum speed Mach 2, but not much interest among foreign buyers.

Features
The YF-17 was made mainly aluminum, in a conventional monohull, although more than 400 kg of its structure was compound of graphite and epoxy. The nose contains a single radar range. The wings had no fuel and areas as the leading edge and output consisted of a nucleus hive -shaped Nomex. The back of the plane was full of aluminum stabilizers and vertical stabilizers were of conventional construction. A aerobraking was located above and between the engines.

The plane was powered with a pair of turbofan General Electric YJ101-GE -110 of 67 kN of thrust each motandos next to each other to reduce the asymmetry in case of loss of an engine. Each engine uses an independent hydraulic system. Unlike the P530, the YF-17 had a partial outline of control fly-by-wire, known as increased electronic control system (ECS).

Testing and evaluation
When the program was announced Light Weight Fighter in 1971, Northrop modified the design P530 P600 would be designated as YF-17A. While the P530 was trying to be a versatile aircraft, the P600 was prepared only for air show and therefore , moved the barrel of the bottom of the fuselage to the top. The design of the YF -17 and YJ101 prototype engine (GE15 engine development) consumed more than one million hours and 5,000 hours in tests wind tunnel.

The first prototype (number 72-1569) was submitted in Hawthorne April 4 of 1974 and made its first flight in Edwards base on 9 June. The second (1972-1570) first flew on 21 August of that year. During 1974, the YF -17 competed against YF-16 Fighting Falcon of General Dynamics. The two prototypes performed 288 test flights with a total of 345.5 hours. The YF-17 attained a top speed of Mach 1.95, a load factor of 9.4 g and a maximum altitude of more than 15 240 m. Could maintain an angle of attack in level flight 34º and 63º on the rise.

The United States Navy had a small stake in the LWF program. In August 1974, Congress ordered the Navy to make maximum use of technology and hardware to LWF new light bomber, the VFAX. As the contractor had no experience with naval fighters, sought business partners to provide expertise. joined General Dynamics LTV Aerospace and Northrop with McDonnell Douglas. Each team sent its revised designs to the needs of the Navy of a radar long-range, multi-purpose capacity.

Origins of the F/A-18
Although Northrop hoped to be the winner because of his years of experience in light fighter design and history of P530, the U.S Air Force selected the YF-16 in January 1975. The YF-16 was slightly faster and used a common engine with the F-15 Eagle. The Navy did not think the YF-16 single engine and narrow landing gear was appropriate or easy to adapt to operations aircraft carrier and refused to adopt the design. In May 1975 the Navy received approval to develop its own aircraft based on the YF-17. By becoming a naval project, the Navy designated as prime contractor McDonnell Douglas. As the requirements of the Navy was different from the USAF, the aircraft was extensively modified: the F/A-18 resulting shared neither the size nor structure of the YF-17.

General Characteristics

 * Crew: 1YF-17_F-18.png
 * Length: 56 ft 0 in (17.0 m)
 * Wingspan: 35 ft 0 in (10.5 m)
 * Height: 16 ft 6 in (5.0 m)
 * Wing area: 350 ft² (32 m²)
 * Empty weight: 17,180 lb (7,800 kg)
 * Loaded weight: 23,000 lb (10,430 kg)
 * Max takeoff weight: 34,280 lb (15,580 kg)
 * Powerplant: 2× General Electric YJ101-100 afterburning turbofans, 14,400 lbf (67 kN) each

Performance

 * Maximum speed: Mach 1.95
 * Range: 2,990 mi (4,810 km)
 * Service ceiling: 50,000 ft (15,000 m)
 * Rate of climb: 50,000 ft/min (250 m/s)
 * Wing loading: 66 lb/ft² (320 kg/m²)
 * Thrust/weight: 1.25

Armament

 * Guns: 1× 20 mm (0.79 in) M61 Vulcan gatling gun
 * Missiles: 2× AIM-9 Sidewinder