The Society of Flight Test Engineers 
                                                   

 


 

ABSTRACT


Georgia Institute of Technology and Lockheed Martin Aeronautics Company

  Unmanned aerial vehicles (UAVs) have a growing role in military aviation, but are not addressed in the flying qualities standard for military aircraft, MIL-STD-1797B. This deficiency is gradually being recognized, but there is little published work assessing MIL-STD-1797B as a standard for unpiloted (or remotely piloted) aircraft. The simulations performed in this study serve as test cases to demonstrate the need for revisions of the standard that specifically address UAVs. The study was limited to lateral-directional flying qualities assessments, and a gust during landing approach was used as the stressing case. Four different sizes of UAVs were simulated responding to a discrete gust at approach speeds, 100 feet above the field. The results showed that roll-mode time constant requirements for gust recovery are strongly dependent on the size of the UAV and can be larger or smaller than the 1797B standard. They also showed that roll control effectiveness requirements could be significantly relaxed (assuming low-altitude gust recovery is the most stressing lateral control task). Additionally, it was found that a revised classification system is necessary in order to apply requirements to a diverse group of military UAVs. This research reveals the need for a new or revised standard. Further research and accumulation of flight test data will be required to create a flying qualities standard that is applicable to all UAVs.