The Northrop/McDonnell Douglas YF-23 was an American single-seat, twin-engine fighter
aircraft technology demonstrator designed for the United States Air Force. The design
was a finalist in the USAF's Advanced Tactical Fighter 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.
Development American reconnaissance satellites first spotted
the advanced Soviet Su-27 and MiG-29 fighter prototypes in 1978, which caused concern in
the U.S. Both Soviet models were expected to reduce the maneuverability advantage of
contemporary US fighter aircraft. In 1981, the USAF requested information from several
aerospace companies on possible features for an Advanced Tactical Fighter to replace the
F-15 Eagle. After discussions with aerospace companies, the USAF made air to air combat
the primary role for the ATF. The ATF was to take advantage of emerging technologies,
including composite materials, lightweight alloys, advanced flight-control systems, more
powerful propulsion systems, and stealth technology. In October 1985, the USAF issued a request
for proposal to several aircraft manufacturers. The RFP was modified in May 1986 to include
evaluation of prototype air vehicles from the two finalists. At the same time, the U.S.
Navy, under the Navalized Advanced Tactical Fighter program, announced that it would use
a derivative of the ATF winner to replace its F-14 Tomcat. The NATF program called for
procurement of 546 aircraft along with the USAF's planned procurement of 750 aircraft.
In July 1986, proposals were submitted by Lockheed, Boeing, General Dynamics, McDonnell
Douglas, Northrop, Grumman and Rockwell. The latter two dropped out of competition shortly
thereafter. Following proposal submissions, Lockheed, Boeing, and General Dynamics formed
a team to develop whichever of their proposed designs was selected, if any. Northrop and
McDonnell Douglas formed a team with a similar agreement. The Lockheed and Northrop proposals
were selected as finalists on 31 October 1986. Both teams were given 50 months to build and
flight-test their prototypes, and they were successful, producing the Lockheed YF-22 and
the Northrop YF-23. The YF-23 was designed to meet USAF requirements
for survivability, supercruise, stealth, and ease of maintenance. Supercruise requirements
called for prolonged supersonic flight without the use of afterburners. Northrop drew on
its experience with the B-2 Spirit and F/A-18 Hornet to reduce the model's susceptibility
to radar and infrared detection. The USAF initially required the aircraft to land and
stop within 2,000 feet, which meant the use of thrust reversers on their engines. In 1987,
the USAF changed the runway length requirement to 3,000 feet, so thrust reversers were no
longer needed. This allowed the aircraft to have smaller engine nacelle housings. The
nacelles were not downsized on the prototypes. The first YF-23, Prototype Air Vehicle 1,
was rolled out on 22 June 1990; PAV-1 took its 50-minute maiden flight on 27 August with
Alfred "Paul" Metz at the controls. The second YF-23 made its first flight on 26 October,
piloted by Jim Sandberg. The first YF-23 was painted charcoal gray and was nicknamed "Spider"
and "Black Widow II", the latter after the Northrop P-61 Black Widow of World War II.
It briefly had a red hourglass marking resembling the marking on the underside of the black
widow spider before Northrop management had it removed. The second prototype was painted
in two shades of gray and nicknamed "Gray Ghost".
Design
The YF-23 was an unconventional-looking aircraft, with diamond-shaped wings, a profile with
substantial area-ruling to reduce drag at trans-sonic 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 on either
side of the aircraft's spine. Of the two aircraft built, the first YF-23 was fitted with Pratt
& Whitney YF119 engines, while the second 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
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 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 "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. Operational history
Evaluation 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. Possible revival
In late 2004, Northrop Grumman proposed a YF-23-based bomber to meet a USAF need for
an interim bomber, for which the FB-22 and B-1R were also competing. Northrop modified
aircraft PAV-2 to serve as a display model for its proposed interim bomber. The possibility
of a YF-23-based interim bomber ended with the 2006 Quadrennial Defense Review, which
favored a long-range bomber with a much greater range. The USAF has since begun the Next-Generation
Bomber program. Aircraft on display
Both YF-23 airframes remained in storage until mid-1996, when the aircraft were transferred
to museums. YF-23A PAV-1, serial number 87-0800, registration
number N231YF, was on display as of 2009 in the Research and Development hangar of the
National Museum of the United States Air Force near Dayton, Ohio.
YF-23A PAV-2, serial number 87-0801, registration number N232YF, was on exhibit at the Western
Museum of Flight until 2004, when it was reclaimed by Northrop Grumman and used as a display
model for a YF-23-based bomber. PAV-2 was returned to the Western Museum of Flight and
was on display as of 2010 at the museum's new location at Torrance Airport, Torrance,
California. Specifications
Data from Pace, Sweetman, Winchester, Aronstein, National Museum of the U.S. Air Force
General characteristics Crew: 1
Length: 67 ft 5 in Wingspan: 43 ft 7 in
Height: 13 ft 11 in Wing area: 900 ft2
Empty weight: 29,000 lb Loaded weight: 51,320 lb
Max. takeoff weight: 62,000 lb Powerplant: 2 × General Electric YF120 or
Pratt & Whitney YF119 turbofan, 35,000 lbf each
Performance Maximum speed:At altitude: Mach 2.2+
Supercruise: Mach 1.6+
Range: over 2,790 mi Combat radius: 750–800 nmi
Service ceiling: 65,000 ft Wing loading: 54 lb/ft2
Thrust/weight: 1.36 Armament
None as tested but provisions made for: 1 × 20 mm 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
See also
Aircraft of comparable role, configuration and era
Lockheed YF-22 Related lists
List of military aircraft of the United States List of fighter aircraft
References Notes
Citations
Bibliography
External links YF-23 photos on DFRC/NASA site
Northrop/McDonnell Douglas YF-23 page on Joe Baugher's site
YF-23 "Black Widow II page on Globalsecurity.org YF-23 "Black Widow II", Northrop/McDonnell
Douglas page on fighter-planes.com YF-23 Enthusiast's Site, includes details
about post-cancellation "YF-23 re-emerges for surprise bid". Flight
International, 13 July 2004.