In the late 1990s, Lockheed Martin was working on an advanced project: a delta-shaped stealth fighter, with no conventional tail section, called the X-44 Manta. Behind the innovation lay an idea to enhance maneuverability and stealth by replacing control surfaces with thrust vector control, a system that steers the aircraft by directing the engine’s thrust. More than two decades later, this concept appears to be one of the pillars by which the Next Generation Air Dominance program of the U.S. Air Force rests.
It was an announcement that came out of the left wing when last year, the U.S. Air Force announced that a prototype aircraft under the NGAD program was already designed, built, and tested. The new jet, this company stated, would represent the most advanced fighter ever built, outclassing the next generation of 5th-generation fighters from Russia and China. On the same day as the announcement, the Air Force released an image of a wedge-shaped aircraft lacking a conventional tail section, and speculation ran rampant regarding any influence of this new design from the X-44 Manta.
The X-44 Manta was designed to be a high-maneuverability, no-tail, multi-axis aircraft without vertical and horizontal control surfaces, but with thrust vector control instead. This was essentially a technology that had already shown much promise in NASA’s F-15 ACTIVE program, an advanced version of the F-15 Eagle that was fitted with both front-wing canards and thrust vectoring jet nozzles to perform nearly every task better than the regular Eagle.
Lockheed Martin proposed a base of their X-44 Manta on the F-22 Raptor because it already has the thrust vector control capability. The F-22, developed from its inception for its ability to penetrate opponent radar and, with an air superiority mission, provided a solid foundation for this technology demonstrator. The X-44 was developed to increase the F-22’s current stealth capability even further by removing the tail section, which greatly adds to the radar return from an aircraft.
Its design also promised several clear advantages in payload capacity and range for the X-44 Manta. Its broad fuselage, in wedge form, would afford it more internal weapons storage and greater fuel efficiency. This design was similar to the F-16XL, which used the same concept to increase lift, range, and payload compared with the ordinary F-16.
Meanwhile, across the Pacific, China’s Chengdu Aircraft Corporation has been making progress toward a stealth fighter. Satellite images of Chengdu’s test airfield from October 2021 reveal a tailless, diamond-shaped airframe that bears a strong resemblance to the X-44 Manta. This airframe, with a wingspan roughly comparable to the J-20, suggests an implication: that China could be working on a tailless design for improved stealth and performance.
Advantages of the tailless design include improved broadband low-observability against a wide range of radar types and optimizing the aircraft’s stealth profile for many angles. Besides, it reduces drag hence can perform sustained dash at high speed, and provides a longer range due to increased fuel capacity.
The problem is, that without vertical tails, stability is hard to achieve, and maneuverability may be lost. High-tech fly-by-wire digital flight controls and thrust vectoring are needed to offset these difficulties. These developments doubtless will be part of the NGAD program and those of its ilk, showing trends toward designs mostly focused on range, payload, speed, and low observability at the detriment of classical maneuverability.
In this cat-and-mouse game between the U.S. and China, which has been pushing the limits of stealth fighter technology, rests the true legacy of the X-44 Manta. Its design principles were progressive enough to shape future air combat and ensure another era of dominance in the skies.