“Flying wing” designs that offer reduced weight and drag when compared to traditional “tube with wings and a tail” designs are theoretically the most efficient aircraft configuration. However, true flying wings are inherently unstable and difficult to control. To aid in the design of future aircraft that utilize such a design, researchers at the German Aerospace Center (DLR) have been performing tests to study the flight characteristics of large flying wing configurations using what has been dubbed a flying “chameleon”. The DLR’s Advanced Technologies Testing Aircraft System (ATTAS) research aircraft resembles a conventional small passenger aircraft, but it has been fitted with special hardware and software to give it the flight characteristics and performance of an entirely different aircraft.
In addition to conventional mechanical flight controls, ATTAS is also equipped with an electrical flight system that allows the researchers to alter the aircraft’s flight characteristics. As well as being able to simulate conventional airplanes, ATTAS is also capable of simulating entirely different aircraft designs. Although ATTAS consists of a cylindrical fuselage with wings and a tail unit, the DKR researchers have been using the craft to carry out flight tests that simulate a flying wing model developed as part of the EU project NACRE (New Aircraft Concepts Research).
“With its special control technology, ATTAS can behave like other aircraft while in the air,” explains Dirk Leibling, a researcher at the DLR Institute of Flight Systems. “This gives us the opportunity to simulate aircraft that do not even exist yet, and to see where we still need to make improvements.” The simulated aircraft consists of a triangular fuselage with two vertical stabilizers at the tail that are tilted slightly outwards to replace the conventional tail fin/rudder and tailplane/elevator combination. There are also four engines under the additional wing area and a wide body designed to accommodate up to 750 passengers on long-haul flights. The simulated flying wing boasts a wingspan of nearly 100 m (328 ft), length of 65 m (213 ft) and maximum take-off weight of roughly 700 tons. Together, its four engines provide a maximum thrust of 1,425 kilonewtons.