NASA has announced it will use a modular, unmanned flight research vehicle being built by Lockheed Martin for the Air Force Research Laboratory (AFRL) to test enabling technologies for new kinds of lightweight, energy-efficient, flexible aircraft. The small aircraft, dubbed the X-56A, will be used to explore ways to suppress vibrations and alleviate the load on flexible aircraft from wind gusts and atmospheric turbulence.
While long, thin flexible wings can significantly reduce the weight of an aircraft, thereby increasing its endurance, they are susceptible to uncontrollable vibrations – or “flutter” – caused from the force of air flowing over them. This force has the potential to seriously damage the aircraft and can result in “catastrophic failure.”
The X-56A, which is also known as the Multi-Utility Technology Testbed (MUTT) flight demonstrator, is powered by twin 52-pound thrust JetCat P200-SX turbine engines, with an additional hard point in the center of the aft upper deck of the fuselage for the mounting of an additional third engine or structural member to enable the testing of joined wing configurations.
The aircraft measures 7.5 feet (2.3 m) long, weighs 480 pounds (217.7 kg) and boasts a wingspan of 28 feet (8.5 m). Its modular design allows for easy wing replacement that the AFRL says will allow for the testing of various flexible wing configurations and a wide range of aerodynamic concepts.
NASA engineers will examine techniques to suppress flutter in real time by deliberately stimulating flutter in flight and actively adjusting software programs in the aircraft’s flight control computer. The researchers also hope to learn how to better alleviate the bending forces placed on wings from wind gusts and atmospheric turbulence – known as gust loads. This knowledge will help improve the safety of flexible aircraft when experiencing in-flight turbulence.
NASA says that, although the X-56A is a low-speed, subsonic research aircraft, the knowledge gained about flutter and gust suppression will also be used in designing the proposed supersonic X-54 - a research and demonstration aircraft being developed by Gulfstream Aerospace for use in sonic boom and supersonic transport research.
The X-56A is being built by Lockheed Martin, which will conduct flight experiments for the AFRL that are scheduled to commence in the northern summer 2012. NASA’s Dryden Flight Research Center will oversee these flights before taking ownership of the aircraft in early autumn for follow-on research.