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Northrop YF-23

YF-23

Role: Experimental fighter prototype
National origin: United States
Manufacturer: Northrop/McDonnell Douglas
First flight: 27 August 1990
Status: Canceled
Primary user: United States Air Force
Number built: 2

The Northrop/McDonnell Douglas YF-23 was a prototype fighter aircraft designed for the United States Air Force. The YF-23 was a finalist in the U.S. Air Force's Advanced Tactical Fighter competition. Two YF-23s were built and were nicknamed "Black Widow II" and "Gray Ghost", respectively. The YF-23 lost the contest to the Lockheed YF-22, which entered production as the Lockheed Martin F-22 Raptor.

Design and development

The YF-22 and YF-23 were competing in the USAF's Advanced Tactical Fighter (ATF) program, conceived in the early 1980s, to provide a replacement for the F-15 Eagle. Contracts for the two most promising designs were awarded in 1986.

The YF-23 was designed to meet USAF requirements for survivability, supersonic cruise (supercruise), stealth, and ease of maintenance. Designed with all-aspect stealth as a high priority, Northrop drew on the company's experience with the B-2 Spirit and F/A-18 Hornet. The YF-23 was an unconventional-looking aircraft with trapezoidal wings, substantial area-ruling, and a V-tail. Similar to the B-2, the exhaust from the YF-23's engines flows through troughs lined with heat ablating tiles, which shields the exhaust from infrared (IR) missile detection from below. The vehicle management system coordinates movements of the control surfaces for maneuvers and for stable flight, along with other aircraft functions. The wing flaps and ailerons deflect inversely on either side to provide roll. Pitch was provided by movement of both V-tails, and yaw was supplied by opposite movement. Deflecting the wing flaps down and ailerons up on both sides simultaneously provided for aerodynamic braking.

Although possessing an advanced design, in order to reduce costs and development, a number of F-15 Eagle components were utilized including the standard F-15 nose wheel unit and the forward cockpit of the F-15E Strike Eagle. Two aircraft were built. YF-23 #1 (PAV-1) was fitted with Pratt & Whitney YF119 engines, while YF-23 #2 (PAV-2) was fitted with General Electric YF120 engines. The YF-23 featured fixed nozzles. The first YF-23 was rolled out on 22 June 1990, and first flew on 27 August 1990. YF-23 #2 first flew on 26 October 1990.

The black YF-23 (PAV-1) was nicknamed "Black Widow II", after the Northrop P-61 Black Widow of World War II and had a red hourglass marking resembling the underbelly marking of the black widow spider. The black widow marking was briefly seen under PAV-1 before being removed at the insistence of Northrop management. The gray colored YF-23 (PAV-2) was nicknamed "Gray Ghost".

Operational history

Evaluation

Both YF-23s were furnished in the configuration specified before the requirement for thrust reversing was dropped. The weapons bay was configured for weapons launch but no missiles were fired, unlike Lockheed's demonstration aircraft. The YF-23s flew 50 times for a total of 65.2 hours. The first YF-23 with P&W engines supercruised at Mach 1.43 on 18 September 1990 and the second YF-23 with GE engines reached Mach 1.6 on 29 November 1990. For comparison, the YF-22 achieved Mach 1.58 in supercruise. The flight testing demonstrated Northrop's predicted performance values for the YF-23.

The YF-22 won the competition in April 1991. The YF-23 design was more stealthy and faster, but the YF-22 was more agile. It has been speculated in the aviation press that the YF-22 was also seen as more adaptable to the Navy's Navalized Advanced Tactical Fighter (NATF), though as it turned out the US Navy abandoned NATF a few months later.

After losing the competition, both YF-23s were transferred to NASA's Dryden Flight Research Center, at Edwards AFB, California without the engines. NASA planned to use one of the aircraft to study strain gauge loads calibration techniques, but this did not occur.

Possible revival

In late 2004, Northrop Grumman proposed a YF-23 based design for the USAF's interim bomber requirement, a role for which the FB-22 and B-1R are also competing. Aircraft PAV-2 was modified by Northrop as a full size model of its proposed interim bomber. The interim bomber requirement has since been canceled in favor of a more long-term, bomber replacement requirement. The same YF-23-derived design could possibly be adapted to fulfill this role as well. However, it appears the possibility of a YF-23-based interim bomber was ended with the 2006 Quadrennial Defense Review, in lieu of a long range bomber with a much greater range.

Aircraft on display

Both airframes remained in storage until mid-1996, when the aircraft were transferred to museums.

YF-23A PAV-1 (s/n 87-0800) is now on display at the National Museum of the United States Air Force in Dayton, Ohio. The aircraft was recently put on display following restoration and is located in the Museum's Research and Development hangar.

Aircraft PAV-2 (s/n 87-0801) was on exhibit at the Western Museum of Flight in Hawthorne, California. In 2004, it was loaned to Northrop Grumman and used for display purposes. Eventually, the aircraft will return to the museum's new location at Torrance Airport, Torrance, CA.

Specifications (YF-23)

Note some specifications are estimated.

Data from Pace, Miller, Winchester

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 (14,970 kg)
Loaded weight: 51,320 lb (23,327 kg)
Max takeoff weight: 62,000 lb (29,000 kg)
Powerplant: 2x— General Electric YF120 or Pratt & Whitney YF119 , 35,000 lbf (156 kN) each

Performance

Maximum speed: Mach 2.2+ (1,650+ mph, 2,655+ km/h) at altitude
Cruise speed: Mach 1.6 (1,060 mph, 1,706 km/h) supercruise at altitude
Range: over 2,790 mi (over 4,500 km)
Combat radius: 865-920 mi (750-800 nmi, 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 x— 20 mm (.79 in) M61 Vulcan cannon
4-6 x— AIM-120 AMRAAM or AIM-7 Sparrow air-to-air missiles
4 x— AIM-9 Sidewinder air-to-air missiles

Comparable aircraft

Lockheed YF-22
Lockheed Martin F-22 Raptor

Bibliography

Goodall, James C. "The Lockheed YF-22 and Northrop YF-23 Advanced Tactical Fighters". America's Stealth Fighters and Bombers, B-2, F-117, YF-22, and YF-23. St. Paul, Minnesota: MBI Publishing Company, 1992. ISBN 0-87938-609-6.
Pace, Steve. F-22 Raptor. New York: McGraw-Hill, 1999. ISBN 0-07-134271-0.
Sweetman, Bill. YF-22 and YF-23 Advanced Tactical Fighters. St. Paul, Minnesota: Motorbooks International Publishing, 1991. ISBN 0-87938-505-7.
Winchester, Jim, ed. "Northrop/McDonnell Douglas YF-23." Concept Aircraft (The Aviation Factfile). Rochester, Kent, UK: Grange Books plc, 2005. ISBN 1-84013-809-2.

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Source: WikiPedia