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AF Research Laboratory tests rocket engine turbopump

  • Published
  • By Kate Blais
  • 95th Air Base Wing Public Affairs
For five seconds on July 12, flames lit up the night sky on the hill of the Air Force Research Laboratory, Propulsion Directorate, Detachment 7 here, as part of a new phase of Upper Stage Engine Technology program testing.

The current phase of the program involves testing a turbopump, the component that essentially drives a liquid rocket engine. Once installed on a rocket engine, the pump pulls the propellants from the storage tanks so they can react and produce thrust, propelling the upper stage of a rocket into space after the lower stage booster runs out and drops off.

"The Air Force is the executive agent for spacelift for the Department of Defense," said Col. Michael Platt, AFRL Det 7 commander. "The results of this test will feed into the validation of the models that we will eventually use to build the next generation engine for an upper stage [engine] system."

As part of the effort to modernize the current upper stage of the Air Force Evolved Expendable Launch Vehicle, this test program is focused on the next generation of design tools that will reduce design time, lower cost and increase fidelity, explained Alan Sutton, AFRL Upper Stage Engine Technology program manager.

The past era of test-driven rocket development -- build it, test it and break it -- has succumbed to a modeling and simulation-based approach.

"We have developed a set of design tools for the engine system, combustion chamber and turbopump," said Sutton. "Today we're looking at using more computer simulation and modeling with physics-based tools so that we can actually look at the bad designs on the computer, try them all out, and then only come to the test stand with a final design for qualification testing."

Operating at 90,000 rotations per minute, this particular turbopump operates at three times the speed of other upper stage engine pumps. The July 12 test initiated the turbopump mapping phase, which is intended to confirm the effectiveness of the modeling and simulation tools used for designing this turbopump.

"This is the part of the program where we're validating our tools that were used to design this turbopump," said Capt. Joshua Hall, AFRL USET deputy program manager and validation lead. "We want to see if our computer models compare to what actual reality is. That way we can validate the tools and say that the physics in the models are functioning correctly and therefore can be used successfully in future programs."

The turbopump is the most complex component of this upper stage test program and creates high-pressure hydrogen to feed a main rocket combustion chamber. As the 16th test in the series, this test was significant because the pump ran at full power for five seconds, while the efficiency of the pump could be mapped out in order to compare test with simulation.

Along with releasing hydrogen exhaust in the form of flames from flare stacks, an enormous amount of data continues to be a product of the program's testing. And the data from two identical, back-to-back tests proved to be exceptionally repeatable.

"In fact, this was the second in a series of the exact same test [performed] just to prove precision and ensure that we get the same result every time," said Platt. "The pump performed exactly as the model predicted. So we feel comfortable going into the sustained duration tests. We're prepared to collect that extended-time data."

Sutton hopes the next phase of testing will involve the combustion chamber, and the rest of the next generation upper stage engine.

"I've been working on the USET program now for 9 years," he said. "This has taken a long time, and we've had a lot of challenges that we've had to go through. But it's been fantastic to see it all come together in the end and see the team come from the beginning stages to have everyone working in unison."