Safe Flight Using One Aerodynamic Control Surface

Civil unmanned aircraft will need to meet stringent safety standards before they are certified to operate in the national airspace of the United States. Reliability is a key requirement for certification. Most current civil unmanned aircraft are not reliable because of the presence of single points-of-failure and the use of low-reliability components. For example: Many fixed-wing unmanned aircraft are equipped with only two aerodynamic control surfaces. A fault in any one surface will usually spell catastrophe. This paper demonstrates how this single point-of-failure can be removed using multi-variable control laws. A single aerodynamic control surface is shown to be sufficient to stabilize the aircraft and execute a set of limited maneuvers. These limited maneuvers are sufficient to safely fly to a landing spot. This concept is proved using flight tests on an unmanned aircraft at the University of Minnesota. The results are also applicable to manned commercial aircraft. Controllability with one surface indicates the large potential to mitigate faults that might otherwise lead to loss-of-control events.