Abstract

General aircraft dynamic stability theory was used to predict the natural frequencies, damping ratios and time constants of the dynamic modes for three specific small UAVs with wingspans on the scale from 0.6 meters to 1.2 meters. Using USAF DatCom methods, a spreadsheet program for predicting the dynamic stability and handling qualities of small UAVs was created for use in the design stage of new small UAV concept development. This program was verified by inputting data for a Cessna-182, and by then comparing the program output with that of a similar program developed by DAR Corporation. Predictions with acceptable errors were made for all of the dynamic modes except for the spiral mode. The design tool was also used to verify and develop dynamic stability and handling qualities design guidelines for small UAV designers. Using this design tool, it was observed that small UAVs tend to exhibit higher natural frequencies of oscillation for all of the dynamic modes. Comparing the program outputs with military handling qualities specifications, the small UAVs at standard configurations fell outside the range of acceptable handling qualities for short-period mode natural frequency, even though multiple test pilots rated the flying qualities as acceptable. Using dynamic scaling methods to adjust the current military standards for the short period mode, a new scale was proposed specifically for small UAVs. This scale was verified by conducting flight tests of three small UAVs at various configurations until poor handling qualities were observed. These transitions were observed to occur at approximately the boundary predicted by the new, adjusted scale.

Degree

MS

College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2004-12-07

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd643

Keywords

Unmanned-Aerial-Vehicles, UAVs, UAV, Dynamic Stability, Static Stability, Handling Qualities, Flying Qualities, USAF DatCom, MIL-F-8785C, Dynamic Scaling, short period, phugoid, dutch-roll, spiral, roll

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