UTSI, AEDC collaboration leads to improved capability in space chamber

  • Published
  • By Janae' Daniels
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  If it doesn't exist - build it.

Faculty, staff and students at the University of Tennessee Space Institute (UTSI) helped Arnold Engineering Development Center (AEDC) do exactly that by building a precise electric propulsion (EP) thrust stand.

According to Dr. Trevor Moeller, assistant professor at UTSI, EP is a form of an in-space rocket motor that is efficient but has very low thrust.

Conventional chemical fuels provide high thrust, but are limited by the amount of fuel carried to orbit. Even communications satellites, which are in geostationary orbits, carry hundreds to thousands of pounds of fuel. EP provides an alternative that requires vastly smaller amounts of fuel because its power comes from the sun.

"A thruster that weighs 200 pounds might produce a half pound to a pound of thrust maximum," Dr. Moeller said. "That's why we need this precise balance mechanism - because of the low thrust levels you have to have a precise measurement."

Joel Davenport, manager of technical research support at UTSI, compared the thrusters to a common, everyday object.

"A house fly weighs 10 milligrams," he said. "We can resolve the thrust that a common house fly would create if it pushed on this mechanism."

According to Davenport, the thrust stand is a very precise, self calibrating balance system that utilizes a Laser Gap Displacement Transducer (LGDT) in its final measurement stage. In order to maintain this precision, a reference platform is automatically leveled to within 1/1000 of a degree of perfect level. Even slight variations in temperature affect the measurements, so chilled water is constantly circulated through it to maintain a constant temperature. The stand is remotely controlled, calibrated and monitored through an intuitive National Instruments LabView control and data acquisition system also developed at UTSI.

Because UTSI was heavily involved in the early stages of EP testing, they were the prime candidate to help build a vertical EP thrust stand that will be delivered later this year to the center's 12-foot vacuum chamber.

"They have expertise as well as contacts with others in the EP world, both NASA and within academia," Jim Burns, 718th Test Squadron lead for space chambers testing, said. "By working with UTSI we are able to tap that range of expertise much more effectively than trying to duplicate it in house."

According to Burns, AEDC saw the need for EP thrusters and began development.

"In the early part of this decade, the nation was looking heavily at EP for all classes for spacecraft, both commercial, DoD and scientific," Burns explained. "One of the important and often forgotten lessons about test facilities is you have to plan and build a test facility before the need arises - working on the EP thrust stand is based on getting ahead of the curve and being ready when the customers need us."

Once the stand is installed, AEDC's goal is to build the customer base.

"We're just getting started," Burns said. "We need the thrust stand to have something to offer to our customers."