Engineering Commons^™

Empirical Modeling Of Tilt-Rotor Aerodynamic Performance, Michael C. Stratton

Mechanical & Aerospace Engineering Theses & Dissertations

There has been increasing interest into the performance of electric vertical takeoff and landing (eVTOL) aircraft. The propellers used for the eVTOL propulsion systems experience a broad range of aerodynamic conditions, not typically experienced by propellers in forward flight, that includes large incidence angles relative to the oncoming airflow. Formal experiment design and analysis techniques featuring response surface methods were applied to a subscale, tilt-rotor wind tunnel test for three, four, five, and six blade, 16-inch diameter, propeller configurations in support of development of the NASA LA-8 aircraft. Investigation of low-speed performance included a maximum speed of 12 m/s and …

Learn-To-Fly Control System Design, Alexander Brent Streit

Electrical & Computer Engineering Theses & Dissertations

In order to improve aircraft flight control system development life cycle, new flight control techniques are being explored to allow the system to ``learn-to-fly" with limited a priori information of the aircraft's aerodynamic characteristics. One approach is to have a system identification process operating on-the-fly to generate mathematical models which can be used to update control laws. In this thesis, a wind tunnel experiment was conducted with a model aircraft set up to be free-to-roll, so system identification and control methods could be explored for a one-degree-of-freedom case. In particular this thesis covers the design of a novel control system …

A Cost Effective Design For A Propeller Thrust/Torque Balance, Nicholas Barrett Sadowski

Mechanical & Aerospace Engineering Theses & Dissertations

Wind tunnel balances are used with aircraft models, propellers, and components to measure applied forces and moments. The design and manufacture of a balance is often for a specific test, test article and conditions. This paper discusses the theory, design, calibration, and testing of a new small propeller balance for use in a low-speed wind tunnel. The new balance is named the ODU15X15.

Theory discussed herein covers how the two measurement components, thrust and torque, affect the balance design. These loads generate strains which are in turn read by strain gages arranged in Wheatstone bridges. The design follows well known …

A Wind Tunnel Technique For The Identification Of Ship Airwake/Rotor Downwash Coupling, Stargel R. Doane

Mechanical & Aerospace Engineering Theses & Dissertations

A wind tunnel study is performed to analyze the interaction between ship airwakes and helicopter rotor downwash. This interaction is of interest to naval aviators and researchers as this phenomenon is thought to limit helicopter flight envelopes and increase the overall difficulty of maritime rotorcraft operations. In this study, a 1/50th scale simplified naval frigate model and appropriately scaled rotor model are used for all experimental work. A rotor thrust survey was conducted in the immediate vicinity of the landing deck. Two dimensional and stereo particle image velocimetry surveys and rotor thrust measurements with various rotor and ship configurations were …

External Aerodynamics Of Heavy Ground Vehicles: Computations And Wind Tunnel Testing, Ilhan Bayraktar

Mechanical & Aerospace Engineering Theses & Dissertations

Aerodynamic characteristics of a ground vehicle affect vehicle operation in many ways. Aerodynamic drag, lift and side forces have influence on fuel efficiency, vehicle top speed and acceleration performance. In addition, engine cooling, air conditioning, wind noise, visibility, stability and crosswind sensitivity are some other tasks for vehicle aerodynamics. All of these areas benefit from drag reduction and changing the lift force in favor of the operating conditions. This can be achieved by optimization of external body geometry and flow modification devices. Considering the latter, a thorough understanding of the airflow is a prerequisite.

The present study aims to simulate …

Experimental Geometry Optimization Techniques For Multi-Element Airfoils, Drew Landman

Mechanical & Aerospace Engineering Theses & Dissertations

A study is reported on geometry optimization techniques for high-lift airfoils. A modern three-element airfoil model with a remotely actuated flap was designed, tested, and used in wind tunnel experiments to investigate optimum flap positioning based on lift. All the results presented were obtained in the Old Dominion University low-speed wind tunnel. Detailed results for lift coefficient versus flap vertical and horizontal position are presented for two airfoil angles-of-attack: 8 and 14 degrees. Three automated optimization simulations, the method of steepest ascent and two variants of the sequential simplex method, were demonstrated using experimental data. An on-line optimizer was demonstrated …