Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Engineering
Rotorcraft Blade Angle Calibration Methods, Brian David Calvert Jr.
Rotorcraft Blade Angle Calibration Methods, Brian David Calvert Jr.
Mechanical & Aerospace Engineering Theses & Dissertations
The most vital system of a rotorcraft is the rotor system due to its effects on the overall flight quality of the vehicle. Therefore, it is of importance to be able to accurately determine blade position during flight so that fine adjustments can be made to ensure a safe and efficient flight. In this study, a current calibration method focusing on the pitch, flap, and lead-lag blade angles is analyzed and found to have larger than acceptable error associated with the sensor calibrations. A literature review is conducted which reveals four novel methods that can potentially increase the accuracy of …
Long-Term Quantitative Study Of Wind-Tunnel Balance Calibrations Across Multiple Calibration Systems, Ryan James Callahan
Long-Term Quantitative Study Of Wind-Tunnel Balance Calibrations Across Multiple Calibration Systems, Ryan James Callahan
Mechanical & Aerospace Engineering Theses & Dissertations
Internal strain-gauge balances are multi-dimensional force transducers widely employed in wind tunnels to obtain accurate aerodynamic force and moment data on an aircraft model. Balances are calibrated periodically to assure measurement accuracy. The calibration provides a mathematical model relating the forces applied to the balance and the output signal from the balance. Currently, there are multiple types of internal strain-gauge balances used in wind-tunnel testing as well as multiple methods by which balances are calibrated. Because of the differences in the hardware and methodologies used to calibrate a wind-tunnel balance, it is hard to quantify the differences seen between the …
A Variable Acceleration Calibration System, Thomas H. Johnson
A Variable Acceleration Calibration System, Thomas H. Johnson
Mechanical & Aerospace Engineering Theses & Dissertations
A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of …
Design, Calibration, And Application Of A Sensor For Measuring Time Dependent Angle Of Attack Of Helicopter Blades, Weiyuan Henry Liu
Design, Calibration, And Application Of A Sensor For Measuring Time Dependent Angle Of Attack Of Helicopter Blades, Weiyuan Henry Liu
Mechanical & Aerospace Engineering Theses & Dissertations
Various pressure probes were designed and tested which could be attached to helicopter blades when a helicopter is in flight. The pressure probes consisted of spherical heads which were held in place by cylindrical shanks. Built inside the heads were transducers to measure the pressure differential between pressure ports which were located on the front portion of the spherical head facing the airstream. Data was obtained over a range of airstream velocity of 11,6 to 88.4- m/s (38 to 290 ft/sec), corresponding to Reynolds numbers of 0.24 to 1.84x105 based on the sphere diameter. Both static and dynamic tests …