The Northrop YF-23 was unofficially named the Black Widow II for the stealth configurations it employed in its contest against the Lockheed YF-22A, in an epic battle of engineering prowess that would determine the US Air Force’s next covert fighter jet.
Although ultimately unsuccessful, the YF-23A was still an incredibly impressive piece of technology, and was in some ways better than the YF-22A, now better known as the F-22 Raptor.
At the beginning of the Reagan administration, and with the McDonnell Douglas F-15 Eagle of the US fleet becoming increasingly outdated, an Advanced Tactical Fighter (ATF) competition was established in June 1981 to find a suitable replacement.
They were to build on the findings of a study called TAC-85 started in the late 1960s, commissioned even before the F-15 entered service, which focused on the concept of an Advanced Tactical Fighter, and in particular the possible stealth capabilities that could be engineered into future jets.
By 1976 the US Air Force (USAF) was interested in incorporating low-observable technology elements into the F-15 successor and developing methods that could enable planes to travel at supersonic speeds without the use of an afterburner, which could reveal positions because of its noticeable exhaust fume.
As a result, two further studies, which were both initially focused on ground-attack missions since the existing F-15 was considered good enough to match any Soviet air threat, called the Enhanced Tactical Fighter (ETF) and the Advanced Tactical Attack System (ATAS) were commenced in 1978.
Although the ETF was shortly discontinued in April 1980, the ATAS, considered a longer-term project and focused on the creation of cutting-edge weapons and technologies, was re-designated as Advanced Tactical Fighter (ATF) the same year.
With the rise of more highly advanced Soviet craft such as the MiG-29, MiG-31, and the Su-27, the program also re-considered its original scope, opting to explore ways they could dominate air-to-air combat again in addition to air-to-ground engagements.
Following the issuance of a Request for Information (RFI) in June 1981, which set out all of USAF’s specifications, 9 aeronautical companies, namely Boeing, Fairchild, Grumman, General Dynamics, McDonnell Douglas, Lockheed, Northrop, Vought, and Rockwell all expressed interest in the project.
USAF were looking for a fighter that could reduce its vulnerability to Surface to Air Missiles (SAMS) by flying supersonically over enemy territory without the need for an afterburner, could employ Short-Take Off and Landings (STOL) so that it could use damaged runaways, had a superior flying range than the F-15 so it could be operated and maintained at sites further away from the battlefield, and that lastly could be cost-effective.
In addition to this, with the emergence of the F-117A Stealth Fighter, renewed confidence in the capabilities of the F-111, and General Dynamic’s and McDonnell Douglas’ successful modification of the F-15 and F-16 fighters into effective strike jets, USAF had a renewed confidence in their air-to-ground abilities, and as a result the ATF was to be principally to focus on the air-air arena.
By the end of 1984, more detailed specifications were drawn up, with the ATP now requiring a cruise speed of Mach 1.5 speed, the ability to accelerate from Mach 0.6 to Mach 1 in 20 seconds and between Mach 0.8 to Mach 1.8 at 20,000 to 30,000 feet within 50 seconds, a maximum gross take-off weight of 50,000 pounds, a combat radius of 700 nautical miles, and a maximum unit cost of $40 million.
At the same time, a competition for the ATP engine, called the Joint Advanced Fighter Engine (JAFE) was also set up, pitting seasoned propulsion specialists General Electric and Pratt & Whitney against each other.
They were instructed to come up with a power-plant that could be self-starting and could reliably perform in a high thrust to weight manner.
In September 1985, rather than having a standard head-to-head competition between two manufacturers to determine the contract winner, a Demonstration and Validation (Dem/Val) competition, which involved the creation of a non-flying prototype that would be exclusively tested on the ground, was announced, with the winner given the privilege of building a working model afterwards.
However, by May 1986 this was revised so that two companies would be chosen at the end of the Dem/Val phase to compete in a conventional fly-off showdown.
In total, 7 companies entered including Boeing, General Dynamics, Lockheed, Grumman, Rockwell, McDonnell Douglas, and Northrop, the latter two of which, realizing that the Dem/Val phase was going to be more expensive than USAF had anticipated, decided to team up and agreed that the winning partner would be the project lead.
In October 1986 it was revealed that Northrop and Lockheed were the victors. Northrop, with McDonnell as the junior partner, were next to compete against Lockheed who had also teamed up with Boeing for the Full Scale Development (FSD) contract that, with USAF stating they were interested in ordering up to 750 units, promised to be a very lucrative prize.
The YF-23A, manned by a single operator, had a height of 13 feet and 11 inches, a length of 67 feet and 5 inches, and a pair of diamond-shaped wings that were swept back at 40 degrees, with a wingspan of 43 feet and 7 inches and a wing area of 900 square feet.
With an altitude ceiling of 65,000 feet and a combat takeoff weight of 62,000 pounds, it was powered by two Pratt & Whitney YF119-PW-100 engines or two General Electric YF120-GE-100 after-burning turbofans, which gave it a maximum speed of Mach 2.0 and a range of 750 to 800 nautical miles.
In order to save weight and maximize stealth, Northrop opted not to use thrust vectoring, a technique allowing the pilot to manipulate thrust from the engine to perform tight maneuvers.
Its body was of sleek design with a smooth lengthwise cross-section engineered to reduce drag and blend together a variety of dimensions, including a modified double trapezoid shape at the fore-body, which housed the cockpit, nose landing gear, electronics, and weapon bays, and a more circular section at the aft region.
It also features two widely separated engine nacelles that transitioned neatly into the wing, underneath of which were trapezoid air inlets linked with inlet ducts that led into the engine and were curved upwards and inwards to deflect radar emission beams coming from the forward direction.
At the forward fuselage, it was installed with a large chine which gave it greater pitch and yaw stability during high angles of attack, an innovation that dramatically boosted its turn performance to such a degree that, without artificially imposed limits, is superior in this aspect to many modern-day fighters.
At the upper fuselage, the YF-23A featured a mid-air refueling array, and at the rear fuselage, it was fitted with two twin V-tails angled at 50 degrees which hid fumes from the engine exhaust.
Fully loaded, it was armed with four AIM-9 Sidewinder missiles deposited inside internal bays at the sides of the engine ducts as well as 4 AIM-120 AMRAAM missiles carried inside an additional internal bay located beneath the air intakes.
In an effort to reduce radar detection, all of the armaments remained inside of the plane, and when released the projectile would be extended into the air stream and the bay doors would immediately shut in order to minimize its radar signature.
Finally, to save money, the manufacturers used components from existing planes, fitting the YF-23A with modified F-18 landing gears as well as a nose and a cockpit salvaged from an F-15.
Testing and Results
Northrop and McDonnell Douglas produced two Prototype Air Vehicles (PAV), the first, known as PAV1 and installed with a Pratt & Whitney engine, was transported to Edward Air Field Base in 1989 where it was unveiled to the public in a ceremony on June 22nd, 1990.
Operated by test pilot Paul Metz, it conducted its first test flight on August 27th, 1990, flying for an hour and encountering a minor issue with the left main gear which failed to latch properly, before it was trialed a further 4 times by September, undergoing a supersonic speed and in-flight refueling evaluation on September 14th.
The second prototype named PAV2, propelled by a General Electric YF120 engine, was finished on October 26th, 1990, and with Paul Metz again at the helm, it was able to match very closely the predicted computer-simulated characteristics while also being the first YF-23A to achieve a ‘super-cruise’ maneuver in which it traveled to Mach 1 speed without employing afterburners.
On the other hand, there were a few minor accidents in follow-up runs, with test pilot Bill Lowe’s outer windscreen shattering at Mach 1.5 speed on October 30th, with the polycarbonate inner layer luckily remaining intact enough for him to perform a safe landing.
A few days before PAV1 was retired, both prototypes flew together in formation over the Mojave Desert on November 29th, and in general, despite some hiccups, they achieved excellent all-round data.
Nevertheless, on April 23rd, 1991, Secretary of the Air Force Donald Rice proclaimed Lockheed’s YF-22A and Pratt & Whitney’s YF119-PW-100 engines as the respective winners of the ATF and JSAF competitions.
Although the YF-23A had superior speed and greater stealth design than its rival and was only trumped by the impressive low-speed maneuverability displayed by the YF-22A, USAF’s decision ultimately hinged on their greater confidence in Lockheed to deliver the program in a timely and cost-efficient manner.
With Lockheed commencing work on what would later become the F-22 Raptor, both YF-23As were placed in storage at Edwards Air Force Base, where after briefly being considered in 1993 by NASA as candidates for the structural testing of composite airframes, were later transferred to the Air Force Museum in Dayton, Ohio and the Western Museum of Flight in Torrance, California, where they still reside today.
More recently, a repeat of the 1991 competition may be in the works, after Northrop-Grumann proposed a modernized version of the YF-23A to the Japanese military who in 2018 announced their desire for a brand new fighter jet, and who have also been approached by Lockheed-Martin.
- Crew: 1
- Length: 67 ft 5 in (20.55 m)
- Wingspan: 43 ft 7 in (13.28 m)
- Height: 13 ft 11 in (4.24 m)
- Empty weight: 29,000 lb (13,154 kg)
- Max takeoff weight: 62,000 lb (28,123 kg)
- Powerplant: 2 × Pratt & Whitney YF119 or General Electtric YF120 afterburning turbofan engines, 35,000 lbf (160 kN) with afterburner
- Maximum speed: Mach 2.2 (1,450 mph, 2,335 km/h) at high altitude
- Range: 2,424 nmi (2,789 mi, 4,489 km)
- Service ceiling: 65,000 ft (20,000 m)