Looks like the sort of software that could usefully migrate across to manned aircraft.
AW&ST:
Damage-tolerant Flight Controls Demonstrated
Rockwell Collins has demonstrated its damage-tolerant flight controls can increase the safety of an in-production unmanned aircraft, with a series of flights on the U.S. Army’s AAI RQ-7 Shadow tactical UAV. The damage-tolerance software was loaded onto the Shadow’s Rockwell Collins-supplied Athena flight-control computer and several flights were conducted to demonstrate safe recovery and landing after various flight control and engine failures, including losing part of the wing.
The flights completed Phase 3 of the U.S. Defense Advanced Research Projects Agency’s Damage Tolerance program. Under previous phases, Rockwell Collins demonstrated safe recovery and landing of a subscale F-18 model after damage including the inflight ejection of 60% of the right wing and 30% of the right horizontal and vertical tails.
In the Shadow trials, the UAV automatically recovered controlled flight and landed itself after both neutral and hard-over failures of ailerons, elevators and flaps, says David Vos, Rockwell’s director of control technologies and unmanned aircraft systems. The outboard 20 in. of one wing—about 10% of its span —was blown off in flight and the UAV automatically recovered and landed, he says. Simulated engine failures and a complete shutdown were also conducted, and the aircraft recovered, selected a landing site and glided to a safe touchdown, Vos says.
“We took a production Shadow off the line, went out with new damage-tolerant flight-control laws and flew five or six flights in a few days, with no multi-month qualification program,” he says. “This was an important milestone. The next step is how we make this a standard solution.”
A 2004 study of Shadow accidents showed 50% were caused by failures on the aircraft, and in 2005 the Army launched a program to improve the reliability of the UAV’s engine. With damage-tolerant controls, Vos says, “When you do have an engine problem, the aircraft lands itself safely.”
The locations of suitable landing sites are loaded into the flight-control system before takeoff. “It always knows where the nearest safe landing site is, autonomously, even if you lose link with the aircraft,” he says. If the engine fails, the system automatically selects the best landing site and plans a trajectory to the runway, Vos says, continuously calculating wind and maneuvers such as a spiral descent and crosswind de-crab before touchdown.
Although Darpa’s Damage Tolerance program is now complete, Vos says Rockwell Collins is continuing research into adding capabilities and functions to its flight-control software.