Since the 1940s, the U.S. X-plane program has been devoted to creating aircraft that are not manufactured for production, but are purely research machines for making aerospace breakthroughs on a fundamental level. This led to innovations such as the supersonic X-1 and the hypersonic X-15. Today, NASA and Boeing are continuing the X-plane tradition with the introduction of a new full-scale, narrow-body Sustainable Flight Demonstrator research aircraft called the U.S. Air Force X-66A.
The main purpose of this aircraft is to study zero-emission aviation and faster, more fuel-efficient passenger flights close to the speed of sound. Engineers face the problem that every airplane is an exercise in compromise. Ideally, they want a glider with a perfect wing mounted on it, but such a wing must have an infinite span, which is not really practical. So engineers have to make compromises.
The X-66A albatross wing is the closest to the TTBW (transonic trussed wing). Its purpose is to fly in the subsonic region at speeds of Mach 0.8 to 1.2. This is the range just before the so-called sonic barrier, when the airplane begins to be subjected to heavy loads that increase drag, make control difficult and cause other problems.
One of the features of the near-sonic region is that the entire plane does not exceed the speed of sound. Instead, the air flowing around different parts of the airplane moves at different speeds. As a result, most of the plane is subsonic and the other parts are supersonic. This leads to problems that must be overcome to reach the right compromise when you don’t have the perfect wing.
The X-66A aircraft is part of NASA’s New Aviation Horizons program, which aims to create faster, more fuel-efficient and environmentally friendly aircraft. This is important not only for airlines looking to build passenger and cargo aircraft capable of near-sonic flight, but also to reduce the environmental impact of aviation.
NASA and Boeing engineers believe the X-66A could be a key element in developing a new generation of aircraft that will be faster, more economical and more efficient. The aircraft will be tested over several years to determine its capabilities and potential.