Development and Initial Testing of a Micro-Newton Torsion Pendulum with Gas-Dynamic Calibration

Smith, Brandon Joseph

Development and Initial Testing of a Micro-Newton Torsion Pendulum with Gas-Dynamic Calibration

dc.contributor.author	Smith, Brandon Joseph	en
dc.contributor.committeechair	Black, Jonathan T.	en
dc.contributor.committeechair	Adams, Colin	en
dc.contributor.committeemember	England, Scott L.	en
dc.contributor.committeemember	Earle, Gregory D.	en
dc.contributor.department	Aerospace and Ocean Engineering	en
dc.date.accessioned	2019-03-06T09:00:21Z	en
dc.date.available	2019-03-06T09:00:21Z	en
dc.date.issued	2019-03-05	en
dc.description.abstract	A novel torsion pendulum thrust test stand for micro-Newton-scale spacecraft thrusters is described. The stand is designed to be robust against electromagnetic interference effects internal or external to the thruster being tested. The design and testing of a gas-dynamic calibration thruster is included. This thruster is fully self-contained on the pendulum arm, with no external wires or feedlines connected to the device and impacting the dynamic response of the underlying pendulum. Initial calibration results are shown. Zero drift and hysteresis are present in the results, evidenced by a constant steady-state displacement drift and a return to a different displacement after shutdown of the calibration thruster. Results are compared to theoretical solutions of the equation of motion. An external forcing function of facility effects is described for discrepancies between results and the theoretical solution. Further work to eliminate these effects and add damping are proposed.	en
dc.description.abstractgeneral	Many recently proposed space missions require very fine vehicle attitude and position control in support of their science objectives. Thrusters with the ability to provide this control are currently in development, from laboratory proofs of concept to initial test flights on pathfinding missions. The low levels of thrust produced by these devices, in the range of less than the weight of a mosquito, require specialized test stands with very fine resolution. This thesis describes a novel torsion pendulum design for measuring these thrusters as well as initial validation results from its calibration system using rarefied gas flow. This calibration device is fully-contained on the device’s arm, removing many common sources of compensation factors which are often needed for other test stand designs. A custom-built displacement measuring system for determining angular motion of the pendulum arm is described which allows for measuring angular displacements of the arm to the level of arcseconds and potentially fractions thereof. Initial results suggest measurement of the expected levels of thrust, while some work remains to remove lingering sources of error and achieve more precise thrust data.	en
dc.description.degree	MS	en
dc.format.medium	ETD	en
dc.identifier.other	vt_gsexam:18939	en
dc.identifier.uri	http://hdl.handle.net/10919/88081	en
dc.publisher	Virginia Tech	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	spacecraft	en
dc.subject	propulsion	en
dc.subject	test facility	en
dc.subject	torsion pendulum	en
dc.subject	gas dynamic flow	en
dc.title	Development and Initial Testing of a Micro-Newton Torsion Pendulum with Gas-Dynamic Calibration	en
dc.type	Thesis	en
thesis.degree.discipline	Aerospace Engineering	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	masters	en
thesis.degree.name	MS	en