The U.S. Defense Advanced Research Projects Agency is looking into adaptive landing gear that would enable helicopters to land and launch on angled, irregular and moving surfaces. The agency demonstrated a concept for such gear at its "What? Wait" future technology forum this week in St. Louis. DARPA noted that the flat, stable surfaces required for use of traditional skid and wheeled landing gear "are often unavailable in helicopter-needy environs such as forward operating areas, ships at sea and natural-disaster zones." Its adaptive system concept replaces standard gear with four articulated, jointed legs equipped with force-sensitive contact sensors in their feet. As each leg extends on landing, DARPA said, its sensor "determines in real time the appropriate angle to assume" to keep the helicopter level and minimize the risk of rotor contact with the surface. (The legs fold up next to the fuselage in flight.) DARPA's program manager, Ashish Bagai, said adaptive gear has numerous potential benefits, including reduced risk of damage during hard landings, stable landing and takeoff on terrain sloping up to 20 deg (more than twice current limits) and irregular terrain and a significant increase in capabilities with a modest increase in landing-gear weight. Developed with funding from DARPA's Mission Adaptive Rotor (MAR) program, the adaptive gear system is undergoing further development by the Georgia Institute of Technology.