Modeling and flight testing of differential thrust and thrust vectoring on a small UAV

Abstract

MODELING AND FLIGHT TESTING OF DIFFERENTIAL THRUST AND THRUST VECTORING ON A SMALL UAV by Zachary J. Merceruio The primary objectives of this research are to mathematically model the propulsion forces applied to the aircraft during nominal, differential thrust, and thrust vectored flight configurations, and verify this modeling through simulation and flight testing experiments. This thesis outlines the modeling process, simulator development, design, and implementation of a propulsion assisted control system for the WVU Flight Control Systems Lab (FCSL) research aircraft. Differential thrust and thrust vectoring introduce additional propulsive terms in the aircraft force equations that are not present when the thrust line passes through the center of gravity. These additional forces were modeled and incorporated into a simulator of the research aircraft. The effects from differential thrust were small and difficult to quantify. The thrust vectoring effects were also found to be small with the elevator having significantly more pitch control over the vectored motors at the simulated flight conditions. Differential thrust was implemented using the on-board computer to command a different thrust level to each motor. The desired thrust differential was programed into a flight scheme based on simulation data, and activated during flight via a control switch on the transmitter. The thrust vectoring mechanism was designed using SolidWorks ® , built and tested outside of the aircraft, and finally incorporated into the aircraft. A high torque servo was used to rotate the motor mounting bar and vector the motors to a desired deflection. Utilizing this mechanism, the thrust vectoring was flight tested, mimicking scenarios tested in simulation. The signal to noise ratio was very low, making it difficult to identify the small changes in the aircraft parameters caused by the vectored thrust. iii Acknowledgments I would firstly like to thank my family for the love and support they have given me throughout this journey. Without their support this would have been a much more difficult undertaking. I would like to thank my committee chairman, Dr. Yu Gu, for offering me a direction, and then guiding me along that path. Also I would like to thank my research advisor and committee member, Dr. Marcello Napolitano, for giving me the opportunity to work in the Flight Controls Research Lab. I would like to thank my remaining committee members, Dr. Gary Morris and Dr. Srikanth Gururajan, for giving me advice and guidance, better preparing me for life after graduate school. I would like to extend a thank you to the flight testing crew who helped me to achieve my research goals. Thank you to the pilots who flew the research platforms beautifully: Mike Eden, Mike Spencer, and Dave Ellis. Thank you to the students who facilitated this research through

The Augmentation of a Flight Control Mechanism for a Hybrid Fixed-Wing VTOL Drone for Parcel Delivery

“…Fig. 2(a) shows the aircraft use lift engines for hover only, and separate engines for cruise only [3]. An aircraft can achieve VTOL capability when it uses the same propulsion system for both cruise and hover just in Fig.…”

OnBoard Parameter Identification for a Small UAV

“…Merceruio [21]. A stand to hold and stabilize the duct and motor was attached to a digital scale so that an increase in thrust would produce an increase in the weight read-out from the scale.…”

“…The Each test run "consisted of setting the throttle on the transmitter to a user defined value, and reading the corresponding force applied to the scale. This was repeated as the throttle was stepped down from full to zero throttle, so that the thrust level would not be affected by a decreased voltage in the battery as the test was performed" [21]. The results of the static thrust testing was a relationship between the throttle PWM signal and the static thrust.…”

“…produces approximately lbs of static thrust[21] and 1.5 lbs of dynamic thrust at the cruise throttle setting.Table 3.1 summarizes the Phastball's overall geometric properties.…”