Modal Analysis and Vibration Test of NASA MSFC Shaker Table

A shaker can be used to simulate launch vibrations and check responses of structures forced at different frequencies. When vibrating at certain frequencies during tests, structural modes of the shaker table itself can cause the test to abort by accelerating too much or by pushing too much electrical gain through the system. Furthermore, structural modes can produce misleading data at these modal frequencies and cause the test article to be under-tested or over-tested. A modal roving hammer test of the horizontal shaker table is conducted to characterize these modes of the shaker table. Two cases were tested in an attempt to simulate the boundary condition of the table on the shaker: free-free and free-fixed. The free-free case revealed a stretching mode at 1334.2Hz while free-fixed showed two stretching modes at 576.7Hz and 1372.3Hz. A subsequent vibration test revealed controlling 20in from the shaker attachment point best controls these modes without drastically over-testing or under-testing

Efficiency from Added Control and Root Cut Out in Infinite Blade Rotorcraft

A dynamic inflow based induced power model for a lifting rotor with an infinite number of blades is analyzed to reveal efficiency of a rotorcraft in forward flight. The model starts from first principals to relate the acceleration potential of an actuator disk to pressure on the lifting blade. Peters and He Ref [3] note that this model provides “overall good correlation with recent measurement data” (xix). This model is extended with the addition of harmonic control, radial control, and root cut out (rco). The addition of these three factors reveal ways to approach the minimum induced power as predicted by Glauert

RC Plane Variable Wing Design

Each year the AIAA (American Institute of Aeronautics and Astronautics) hosts a design competition where college teams design and fly a small, remote-controlled, battery-powered airplane. For this competition, scoring primarily depends upon the following: maximizing payload, maximizing speed, minimizing weight, minimizing wingspan. Since wingspan is a key scoring factor and variable wing geometry is allowed, our design team has decided to design a pivoting wing system that can be remotely activated immediately before and after takeoff and landing respectively