Northrop YF-23

https://en.wikipedia.org/wiki/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, nicknamed "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 2010.

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 (610 m), which meant the use of
thrust reversers on their engines. In 1987, the USAF changed the runway length
requirement to 3,000 feet (910 m), 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 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.


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
1989–1990

Number built
2

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.

Japan launched a program to develop a domestic 5th/6th generation (F-3) fighter
after the US Congress refused in 1998 to export the F-22. After a great deal of
study and the building of static models, the Mitsubishi X-2 Shinshin testbed
aircraft flew as a technology demonstrator from 2016. By July 2018, Japan had
gleaned sufficient information, and decided that it would need to bring on-board
international partners to complete this project. One such company that responded
was Northrup Grumman and there is speculation that it will offer a modernized
version of the YF-23 to Japan.

Specifications (YF-23)

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 × Pratt & Whitney YF119 or General Electric YF120 afterburning
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