Compared with the YF-22, the stealth fighter YF-23 possesses an extremely unique aerodynamic design.


Behind every military aircraft that entered production and service was numerous failures. It may be due to the project’s ambition too much, beyond the technological capabilities of the manufacturer at the time, but for the YF-23, it was a pity.

The YF-23 possesses non-traditional breakthrough features and design, but unfortunately, this aircraft was prematurely killed, by the rival YF-22 Raptor.


When the Soviets’ Mig-29 and Su-27 were discovered in 1978, US Air Force officials were concerned that the two fighters could be heavy adversaries, even outperforming the US Air Force’s F-15, especially in terms of maneuverability.

To maintain the absolute advantage of the air force, the Pentagon has ordered many of the country’s defense contractors to research and develop a new aircraft under the program “Advanced Tactical Fighter”. It must meet requirements such as high survivability, supersonic cruise speed, be able to operate covertly, reduce radar reflection, and reduce maintenance costs.

In July 1986, after considering the detailed project of the contractors, the Pentagon selected only the last two prototypes, Northrop Grumman’s YF-23 and Lockheed Martin’s YF-22. Basically, both versions of these fighters were built with high stealth capabilities.

As a result, the YF-22 was the winner, and became the cult F-22 Raptor in the US 5th generation fighter family. So, what was failure of YF-23?


The YF-23 prototype was produced and delivered to the US Air Force in 1989, and evaluated in 1991.

Compared with the YF-22, the stealth fighter YF-23 possesses an extremely unique aerodynamic design. Viewed from above, the YF-23 has a diamond-style main wing and no horizontal stabilizer at the tail.

The YF-23 has a length of 20.6 meters (67 ft 5 in), a wingspan of 13.3 meters (43 ft 7 in), a height of 4.3 meters (13 ft 11 in), and a maximum takeoff weight of 29 tons (62,000 lb).

One of the most impressive points besides the main wings was the design of the engine exhaust of the aircraft. Accordingly, instead of facing sideways like the traditional engine, the exhaust rings were directed upwards, providing good infrared shielding. The jet exhaust was covered with an insulation material developed by Allison, which prevents infrared detection from behind.

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 YF-23 has better supersonic cruise capabilities than the YF-22 at Mach 1.8, thanks to its General Electric YF120 engines. Northrop analyst Barry Watts said that, even equipped with lower-powered Pratt & Whitney YF119 engines, the YF-23 was still capable of supersonic cruise at Mach 1.4.

In terms of range, the YF-23 was also more impressive than the design of Lockheed Martin when it had a range of 4,500 km, larger than the 3,200 km of the YF-22.

The YF-23 could carry a variety of weapons available in the US inventory, and it also had modern avionics that could be operated in all weather conditions. Its stealth was also impressive thanks to its radar-absorbent coating to avoid enemy detection and pursuit.

Why did the YF-23 not win?

Despite possessing these outstanding advantages, on April 23, 1991, the YF-23 had to pityfully accept the defeat, watching the opponent chosen to become the official stealth fighter model of the US. The failure of the YF-23 can be explained by the following reasons:

The first was the political issue. According to some sources, Northrop and its partner McDonnell Douglas had a bad reputation in the B-2 and A-12 aircraft program, making the Pentagon unhappy. They feared the same thing would happen to the Advanced Tactical Fighter program, so they decided to give Lockheed Martin the chance with the YF-22.

The next reason was the vision in the design of stealth fighter. While Northrop mechanically complied with the US Air Force’s requirements to the ATF, Lockheed has shown a vision beyond what the US Air Force envisages. The design of the YF-23 was the perfect combination of speed, altitude and stealth. Meanwhile, the view of the US Air Operations Command was skeptical of the ability to effectively operate stealth features in practice. Instead, they wanted to make sure the aircraft in the ATF project had to be flexible enough to defeat the airborne threats in sight.

The F-22 is equipped with dual Pratt & Whitney F119-PW-100 augmented turbofan engines are closely spaced, and incorporate pitch-axis thrust vectoring nozzles, that give it excellent maneuverability. Pentagon officials have been overly cautious and concerned about the risk of their aircraft being overtaken by Russia in terms of maneuverability and agility, and the F-22 has satisfied them.

In addition, the reason the YF-23 was not selected was the issue of the US Navy. Although not participating in the ATF, but the US Navy still had the right to choose the winner. At that time, the navy was pursuing the Navalized Advanced Tactical Fighter program (NATF).

According to Sherm Mullin, head of the Lockheed fighter’s project at the time, they attempted to come up with a naval version of the YF-22, a plane looked like bizarre hybrid of a Raptor and F-14 Tomcat with variable geometry wings. That was also what the US Navy expected. Of course, the YF-23 didn’t appeal to US Navy officials. However, the US Navy was later forced to cancel the NATF project in order to participate in the Joint Strike Fighter program. Some naval officials have expressed bitterness about this choice.

Those are the reasons that led to the failure of YF-23. Mr. Barry Watts, an analyst at Northrop Corporation once described, YF-22 as a “Super F-15” exactly what the Air Force wants. When the YF-22 prototype was selected for the ATF program, it was renamed the F-22 Raptor.

Pratt & Whitney also won with the F119 engine, though not as powerful as General Electric’s, but more reliable.

As a result, the Lockheed corporation created a fighter with unprecedented performance. However, if the YF-23 was to be chosen, it could be a superior fighter.

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