Northrop YF-23

The Northrop/McDonnell Douglas YF-23 was an American single-seat, twin-engine stealth fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, battling the Lockheed YF-22 for a production contract. Two YF-23 prototypes were built with the nicknames "Black Widow II" and "Gray Ghost".

In the 1980s, the USAF began looking for a replacement for its fighter aircraft, especially to counter the USSR's advanced Sukhoi Su-27 and Mikoyan MiG-29. Several companies submitted design proposals; the USAF selected proposals from Northrop and Lockheed. Northrop teamed with McDonnell Douglas to develop the YF-23, while Lockheed, Boeing and General Dynamics developed the YF-22.

The YF-23 was stealthier and faster, but less agile than its competitor. After a four-year development and evaluation process, the YF-22 was announced the winner in 1991 and entered production as the Lockheed Martin F-22 Raptor. The U.S. Navy considered using the production version of the ATF as the basis for a replacement to the F-14, but these plans were later canceled. The two YF-23 prototypes were museum exhibits as of 2009.


Northrop YF-23
Class Aircraft
Type Fighter
Manufacturer Northrop Corporation
Production Period 1989 - 1990
Origin United States of America
Country Name Origin Year
United States of America 1990
Country Name Operational Year Retirement Year
United States of America View
ManufacturerName Production From Production To Quantity
Northrop Corporation 1989 1990 View
McDonnell Douglas 1989 1990 View

The YF-23 was an unconventional-looking aircraft, with diamond-shaped wings, a profile with substantial area-ruling to reduce aerodynamic drag at transonic speeds, and an all-moving V-tail. The cockpit was placed high, near the nose of the aircraft for good visibility for the pilot. The aircraft featured a tricycle landing gear configuration with a nose landing gear leg and two main landing gear legs. The weapons bay was placed on the underside of the fuselage between the nose and main landing gear. The cockpit has a center stick and side throttle.

It was powered by two turbofan engines with each in a separate engine nacelle with S-ducts to shield engine axial compressors from radar waves. on either side of the aircraft's spine. Of the two aircraft built, the first YF-23 (PAV-1) was fitted with Pratt & Whitney YF119 engines, while the second (PAV-2) was powered by General Electric YF120 engines. The aircraft featured fixed engine nozzles, instead of thrust vectoring nozzles as on the YF-22. As on the B-2, the exhaust from the YF-23's engines flowed through troughs lined with heat-ablating tiles to dissipate heat and shield the engines from infrared homing (IR) missile detection from below.

The flight control surfaces were controlled by a central management computer system. Raising the wing flaps and ailerons on one side and lowering them on the other provided roll. The V-tail fins were angled 50 degrees from the vertical. Pitch was mainly provided by rotating these V-tail fins in opposite directions so their front edges moved together or apart. Yaw was primarily supplied by rotating the tail fins in the same direction. Test pilot Paul Metz stated that the YF-23 had superior high angle of attack (AoA) performance compared to legacy aircraft. Deflecting the wing flaps down and ailerons up on both sides simultaneously provided for aerodynamic braking.

To keep costs low despite the novel design, a number of "commercial off-the-shelf" components were used, including an F-15 nose wheel, F/A-18 main landing gear parts, and the forward cockpit components of the F-15E Strike Eagle.

The first YF-23, with Pratt & Whitney engines, supercruised at Mach 1.43 on 18 September 1990, while the second, with General Electric engines, reached Mach 1.6 on 29 November 1990. By comparison, the YF-22 achieved Mach 1.58 in supercruise. The YF-23 was tested to a top speed of Mach 1.8 with afterburners and achieved a maximum angle-of-attack of 25°. The maximum speed is classified, though sources state a maximum speed greater than Mach 2 at altitude and a supercruise speed greater than Mach 1.6. The aircraft's weapons bay was configured for weapons launch, and used for testing weapons bay acoustics, but no missiles were fired; Lockheed fired AIM-9 Sidewinder and AIM-120 AMRAAM missiles successfully from its YF-22 demonstration aircraft. PAV-1 performed a fast-paced combat demonstration with six flights over a 10-hour period on 30 November 1990. Flight testing continued into December. The two YF-23s flew 50 times for a total of 65.2 hours. The tests demonstrated Northrop's predicted performance values for the YF-23. The YF-23 was stealthier and faster, but the YF-22 was more agile.

The two contractor teams submitted evaluation results with their proposals in December 1990, and on 23 April 1991, Secretary of the Air Force Donald Rice announced that the YF-22 was the winner. The Air Force selected the YF119 engine to power the F-22 production version. The Lockheed and Pratt & Whitney designs were rated higher on technical aspects, were considered lower risks, and were considered to have more effective program management. It has been speculated in the aviation press that the YF-22 was also seen as more adaptable to the Navy's NATF, but by 1992 the U.S. Navy had abandoned NATF.

Following the competition, both YF-23s were transferred to NASA's Dryden Flight Research Center at Edwards AFB, California, without their engines. NASA planned to use one of the aircraft to study techniques for the calibration of predicted loads to measured flight results, but this did not take place.

Role Stealth fighter technology demonstrator
National origin United States
Manufacturer Northrop/McDonnell Douglas
First flight 27 August 1990
Status Canceled
Primary user United States Air Force
Produced 1989–90
Number built 2


General characteristics

  • Crew: 1 (pilot)
  • Length: 67 ft 5 in (20.60 m)
  • Wingspan: 43 ft 7 in (13.30 m)
  • Height: 13 ft 11 in (4.30 m)
  • Wing area: 900 ft2 (88 m2)
  • Empty weight: 29,000 lb (13,100 kg)
  • Loaded weight: 51,320 lb (23,327 kg)
  • Max. takeoff weight: 62,000 lb (29,000 kg)
  • Powerplant: 2 × General Electric YF120 or Pratt & Whitney YF119 turbofan, 35,000 lbf (156 kN) each

Performance

  • Maximum speed:
    At altitude: Mach 2.2+ (1,450+ mph, 2,335+ km/h)
    Supercruise: Mach 1.6+ (1,060+ mph, 1,706+ km/h)
  • Range: over 2,790 mi (over 4,500 km)
  • Combat radius: 750–800 nmi (865–920 mi, 1,380–1480 km)
  • Service ceiling: 65,000 ft (19,800 m)
  • Wing loading: 54 lb/ft2 (265 kg/m2)
  • Thrust/weight: 1.36

Armament

  • None as tested but provisions made for:
    1 × 20 mm (0.79 in) M61 Vulcan cannon
    4 × AIM-120 AMRAAM or AIM-7 Sparrow medium-range air-to-air missiles
    2 × AIM-9 Sidewinder short-range air-to-air missiles

End notes