Semester

Fall

Date of Graduation

2012

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Wade W Huebsch

Committee Co-Chair

Patrick H Browning

Committee Member

Gary J Morris

Abstract

The micro air vehicle (MAV) is a relatively new class of Unmanned Aerial Vehicles (UAVs) and has drawn much interest in recent years within the aerospace industry, especially for military surveillance applications. The aerodynamic characteristics of existing MAV designs have been documented in aeronautics literature; however, the MAV presented in this research had unusual design specifications in which the overall mass and cruise speed were greater in comparison to the existing designs. Additionally, the MAV was designed to transform from ballistic flight to aircraft flight for the purpose of gaining performance improvements in both range and accuracy. This new MAV design consists of a two-stage deployment process of its control surfaces in which the tail fins are first deployed immediately after being launched from a tube system followed by deployment of the wings at the apex of the original ballistic trajectory. This research effort incorporated a relatively new simulation tool that couples computational fluid dynamics (CFD) analysis with 6-DOF flight prediction. This coupling is being called numerical flight testing; it has allowed the numerical prediction for the aerodynamic flight behavior of the MAV in free flight motion. Prior to conducting numerical simulations of free flight motion, several, more traditional, CFD simulations were executed for a range of angles of attack in which the airflow traveled relative to the fixed body. Once the aerodynamic results were obtained, the MAV was optimized for the maximum lift-to-drag and the tail was trimmed to balance the forces on the body and generate negligible rotation about the pitch axis. With the known location of the center of gravity, the baseline was determined to be gyroscopically stable. This was confirmed with experimental data. A major concern addressed in this research was the resulting dynamics of the MAV once deployment of the tail and wings was complete, and how this affected the follow-on flight dynamics. Therefore, a total of four numerical flight tests were conducted in the MAV's various configurations. Because of the limited computational performance capabilities, an analysis of the MAV's complete flight trajectory could not be achieved. The first simulation was executed on the MAV in the stowable configuration (i.e. baseline) immediately upon launch from the barrel of the tube to evaluate its dynamic stability. Upon deployment of the tail, a simulation was performed to provide a prediction of the projectile's stability as well as its rate of spin decay and time required to de-spin. The final two simulations were conducted upon deployment of the wings using two different tail configurations in which its longitudinal and lateral-directional stability were analyzed. In addition to this analysis, the aerodynamic force characteristics were examined.

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