YF-23 Black Widow II

Northrop YF-23 Black Widow II gray ghost

The Northrop/McDonnell Douglas YF-23 was an American prototype fighter aircraft designed for the United States Air Force. The YF-23 was entered in Advanced Tactical Fighter competition but lost out to the Lockheed YF-22, which entered production as the 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, with the YF-23 delivered in 1989 and the evaluation concluded in 1991.[1]

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 diamond-shaped wings, substantial area-ruling, and a V-tail.[1] It introduced the novel feature of rear jet nozzle troughs lined with heat ablating tiles developed by Allison, which shielded the exhaust from IR detection from below. All the control surfaces were coupled together via the Vehicle Management System to provide "net effect" aerodynamic control. The wing flaps and ailerons deflected inversely on either side to provide yaw, while the tail provided pitch. Aerodynamic braking was achieved by deflecting the flaps and ailerons on both sides simultaneously.

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.[1]

Two aircraft were built. PAV-1 was fitted with Pratt & Whitney YF119 engines, while PAV-2 was fitted with General Electric YF120 engines. The YF-23 featured fixed nozzles.[1]

The black YF-23 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.[2] The gray colored YF-23 was nicknamed "Gray Ghost".[3]

[edit] Operational history

[edit] Evaluation
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Northrop's original ATF concept from 1986. Note how close this was to the final design in terms of overall configuration, though without stealth features
Northrop's original ATF concept from 1986. Note how close this was to the final design in terms of overall configuration, though without stealth features

Both aircraft were furnished in the configuration specified before the requirement for thrust reversing was dropped, although there has never been any mention as to whether this feature was tested or not.[citation needed] The weapons bay was not configured for weapons launch and no missiles were carried, unlike Lockheed's demonstration aircraft. Northrop chose to demonstrate this capability using computer simulations.[citation needed] The configuration of the weapons bay has never publicly been revealed.[citation needed]

Although the precise results of the evaluation and the reasons justifying the final decision are not public knowledge and probably never will be due to commercial litigation issues,[citation needed] the USAF chose the winning team based on an awarded points system, which put the YF-22/PW F119 combination slightly ahead of the three other combinations.[citation needed]

The YF-22 won the competition in April 1991. 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.[4]

After losing the competition, both YF-23 prototypes were transferred from Northrop to NASA's Dryden Flight Research Center, at Edwards AFB, California. The engines were removed. NASA had no plans to perform flight tests with the airframes, but a proposal was put forward to use one of the two aircraft to study strain gauge loads calibration techniques. The possible production configuration of the F-23A has never been publicly revealed.

In the end, however, both aircraft remained in storage until the summer of 1996, when the aircraft were transferred to museums. Aircraft PAV-2 was in exhibit at the Western Museum of Flight in Hawthorne, California and PAV-1 was recently moved to the National Museum of the United States Air Force near Dayton, Ohio, where it sits in the Aircraft Restoration Hangar[5] fully assembled, painted and with stencils as of September 2008 before put on display in the museum.[citation needed] Aircraft PAV-2 is now on display in an outdoor parking area at Northrop Grumman's production facility in El Segundo, California.

[edit] 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 moved from the Western Museum of Flight to Northrop's plant for refurbishment after being on outside display for more than a decade. Instead, Northrop used the aircraft to create a full scale model of its proposed interim bomber. The interim bomber requirement has since been canceled in favor of a more long-term, permanent bomber replacement requirement. The same YF-23-derived design could possibly be adapted to fulfill this role as well, however.[6]

[edit] Specifications (YF-23)

Note some specifications are estimated.

Data from F-22 Raptor book[7]

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 (29,029 kg)
* Powerplant: 2× 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+ est. (1,060+ mph, 1,706+ km/h) supercruise at altitude
* Combat radius: 865-920 mi [8] (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× 20 mm M61 Vulcan cannon
* 4× air-to-air missiles, AIM-120 AMRAAM and AIM-9 Sidewinder