SensorCraft Free-Flying Aeroservoelastic Model: Design and Fabrication

Abstract

3NextGen Aeronautics, Torrance, CA, 90505 The SensorCraft Aerodynamic Efficiency Improvement (AEI) program, a combined research effort of the Air Force Research Laboratory (AFRL), NASA, and the major defense contractors of Boeing, Lockheed Martin, and Northrop Grumman, have successfully demonstrated active control of an aeroelastically scaled model of three large flexible aircraft concepts within wind tunnel tests conducted at NASA Langley Transonic Dynamics Tunnel (TDT). Each model was free to maneuver in pitch and plunge, enabling free-flight within the test section, which facilitated the testing of active trim controllers, flutter suppression strategies, as well as Gust Load Alleviation (GLA). While the purpose of the program was aimed at technology advancements to reduce the structural weight of a future SensorCraft vehicle, innovation was also required to develop the model and support systems which would make such a demonstration possible. NextGen Aeronautics, under contract for each of the prime defense firms involved, was integral in the design and fabrication of the unique solutions required by this effort. This paper will focus on NextGen’s contributions to the Boeing AEI program, under which an aeroelastically scaled full span model of the joined wing SensorCraft was developed. To meet the aggressive objectives of the test program, a small multi-disciplinary team with a background in flutter model design and fabrication leveraged the simultaneous use of several modern engineering tools to evaluate the ramifications of all critical design decisions. The design, fabrication, and validation test procedures will all be addressed in this document. The model was successfully tested in three separate entries at NASA Langley TDT. The first was a static entry, where balance data was collected in addition to vehicle dynamic data. The second and third entries were completed with the model mounted on a dynamic support system, which enabled free flight of the vehicle in pitch and plunge. In its final form, the model consisted of 13 actively controlled surfaces driven by rotary vane actuators via high performance hydraulic servo-valves, over 80 channels of data flow from accelerometers, strain gages, RVDTs, and hot-film sensors, all packaged within the constraints of an aeroelastically scaled model.