Design and Trim Optimization of a Flying Wing UAV
Open Access
- Author:
- Quindlen, John Francis
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jacob Willem Langelaan, Thesis Supervisor
Jacob Willem Langelaan, Thesis Supervisor
Dr. Mark David Maughmer, Thesis Honors Advisor
Dr. George A Lesieutre, Faculty Reader - Keywords:
- flying wing
UAV
trim - Abstract:
- Camber changing plain flaps offer tailless sailplanes two potential benefits: a lower minimum speed, ideal for climbing in thermals, and a higher lift-to-drag ratio for soaring in between thermals. With these two goals in mind, an inboard plain flap is designed for one of The Pennsylvania State University’s existing flying wing unmanned aerial vehicles (UAV). The flap places new demands on the aircraft’s autopilot which must be alleviated with a new flap module. In order to do so, the aerodynamic derivatives of the original aircraft are linearized. Then an inboard flap is designed to require little change in elevon deflection to trim the aircraft for any flap deflection. Next, a nonlinear longitudinal dynamics model is created using the new linearized aerodynamic derivatives of the flapped aircraft. These nonlinear dynamics are then linearized to find the transfer functions of airspeed to pitch angle and pitch angle to elevon deflection. From these two equations of motion, an airspeed controller is designed and optimized using root locus method for a proportional-integral (PI) controller and a proportional-integral-derivative (PID) controller. Just as expected, the inboard flap improves the aircraft’s performance. After implementing the flap, the lift to drag ratio of the flapped aircraft improves slightly versus the original aircraft. The new configuration offers an average increase in lift to drag ratio of 1% at cruise from 10 m/s to 15 m/s with a maximum improvement of 2% at 12 m/s. Likewise, the aircraft sees roughly a 22% decrease in minimum airspeed at a 15 degree angle of attack using a 28 degree flap deflection versus the original aircraft at the same angle of attack. Further simulation results of the new flapped configuration are then analyzed and compared with the original aircraft. The flap module performs well within the cruise range but is of limited effectiveness at either end of the airspeed range.