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Northrop YF-23

At the height of the cold war, the Americans and the Soviets were in a constant race to develop the newest, fastest jets. This airborne arms race gained even more focus from the United States when satellites over the Soviet Union spotted two new aircraft: the Su-27 and the MiG-29. These were prototype jets that had been specifically designed to counter the top US fighter jets at the time, such as the F-15, meaning that the US was faced with the realization that they might not have undisputed air superiority anymore. Immediately, the Air Force drew up plans for a next-generation aircraft, the YF-23 Grey Ghost, who would be unmatched in speed and stealth.


In the year 1981 the United States Air Force sent a list of requirements to seven aircraft manufacturers who were interested in the contract. The aircraft was to be an Advanced Tactical Fighter, or ATF. Companies were expected to make use of recent innovations in fields like stealth technology and autopilot systems.

In 1986, the Air Force received blueprints from 5 companies: Northrop, McDonnell Douglas, General Dynamics, Lockheed, and Boeing. The companies were all aware that this could be one of the most profitable contracts of all time – the Air Force wanted 750 of the finished jets and the Navy had even expressed interest in purchasing over 500 of them. With this in mind, three of the companies, Lockheed, General Dynamics, and Boeing, came to an agreement that they would all work together on the project if any of their designs was chosen. In response to this newly formed team, McDonnel Douglas and Northrop also joined forces, ready to share the profits.

Out of the 5 aircraft proposals, the Air Force announced that Lockheed and Northrop had the best designs and gave each company four years to produce a prototype, which would later be known as the Lockheed YF-22 and the Northrop YF-23.

The first YF-23 was completed in 1990 and immediately flew its first test flight, which lasted about an hour. It was painted a charcoal gray, and in honor of Northrop’s P-61 Black Widow, a World War 2 plane that was the first to ever be equipped with radar, the first YF-23 was nicknamed the Black Widow 2, and it even had the distinctive red hourglass on its underbelly shared by the venomous spider, but Northrop executives removed it when they found out. The second prototype was built the following year and was painted in two shades of grey, earning the name The Grey Ghost.

The most striking feature of the YF-23 was its wings, which had an unconventional diamond shape. The tail was shaped like a wide V. Between the tailfins were the two jet engines, who had been designed with S-ducts. Aircraft with S-ducts feature the intake for the engines at the rear of the plane a little higher up than the engines, and the exhaust is behind and a bit lower than the engines, giving the system the overall shape of the letter S. These engines have the benefit of shielding the front and sides of the engines from radar and are also easy to service. Along with this unique engine design the exhaust was also vented through specially made heat absorption layers, that would dissipate the heat from the engines and make it difficult for heat-seeking missiles to lock onto the aircraft from below.

The YF-23 was 67 feet long, that’s about 20 meters, and had a wingspan of 43 feet, or 13 meters. The interior of the plane only had space for the pilot, as the aircraft was intended to have minimal weight and maximum speed and range. It’s estimated range was 2,800 miles or about 4,500 kilometers.

The first prototype, the Black Widow 2, was powered by 2 YF119 engines designed by Pratt and Whitney, but for the second prototype, the Grey Ghost, they opted to mix things up and instead used two Turbofans from General Electric. The Grey Ghost turned out to be the faster of the two, and though the official maximum speed is still classified, sources have reported that it reached mach 2.2. That’s nearly 1500 miles per hour or 2300 kilometers per hour.

Pratt and Whitney
Pratt and Whitney turbine

Test pilots praised the YF-23 for its speed, mobility, and excellent angle of attack. Even when not blasting its afterburners to reach its maximum speed, it could comfortably cruise at mach 1.6, putting it in the speed range of the newer Soviet jets mentioned earlier. It was made compatible for an M61 Vulcan machine gun in its nose, and because its focus was to be air-to-air combat, its wings had space for up to 6 anti-aircraft missiles.

But as impressive as these details are, it wasn’t quite enough to beat out the competition.


The YF23 wasn’t the only one competing for the spot of the Advanced Tactical Fighter. As mentioned earlier, Boeing, General Dynamics, and Lockheed had all teamed up with their own version, the YF-22. The two began their competing test flights in late 1990, each racking up about 60 hours of total flight time. The Grey Ghost was also equipped with its missiles and main cannon, but never fired a shot.

Northrop YF-23 PAV-1 in flight.
Northrop YF-23 PAV-1 in flight.

By the end of the evaluation, the Air Force selected the YF-22 as the winner. The Grey Ghost had performed just as predicted by Northrop and was considerably stealthier than the competition and had a higher maximum speed, but Lockheed’s YF-22 was superior in several ways. Mainly, it was more agile, which the Air Force saw as crucial for air-to-air combat. It was also speculated that it was chosen because it had higher potential for landing on aircraft carriers, but the Navy actually withdrew their plan to purchase advanced fighters a year later. The YF-22 went on to full production and eventually became the Lockheed Martin F-22 Raptor, one of the most advanced aircraft in the Air Force. Currently the US has built 195 F-22s.

The Northrop YF-23s, on the other hand, now had no purpose. They were stripped of their engines and sent across the country to NASA’s Dryden Flight Research Center, but NASA never got around to testing them like they wanted. Today, both prototype YF-23s are on display for the public: one is in the National Museum of the United States Air Force in Ohio, and the other is in the Western Museum of Flight in California.

While it’s highly unlikely that the original YF-23 program will be revived, there is a chance it could become the model for newer aircraft. For example, in 2004 the United States Air Force was looking into a new interim bomber, or tactical range bomber, that could reach targets surrounded by heavy defense or difficult geography. Northrop joined the competition and designed a stealth bomber based on the YF-23, but the project never went anywhere as the Air Force cancelled their request, turning their attention instead to the Next Generation Bomber program.

More recently, Japan has been looking into developing its next generation of fighter jets, and after being denied F-22s, they reached out to several companies for possibly designing their next aircraft. Northrop is one of the companies that expressed interest in the offer, so while their original YF- 23 never made it to full production, we could soon see its revival in the form of a new Japanese stealth fighter.

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