Engineers Find Fixes For Potential Thrust Oscillation Problem on Ares

Article written: 22 Dec , 2009
Updated: 19 Dec , 2015
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Will the Ares rocket stay or will it go? For now, no one knows, but NASA engineers have developed multiple options for “de-tuning” the Ares I rocket to prevent any problematic thrust oscillations that could potentially expose astronauts to dangerous levels of vibrations as the rocket climbs to orbit with the Orion crew vehicle atop. Even though the Ares I-X test flight showed no problematic thrust oscillation vibrations took place during the flight, engineers believe they have found a solution to preclude it from actually ever happening with any future Ares rocket. Read the details below; and enjoy this video round-up of everything that happened with the Constellation program in 2009.

Even though rumors abound that the Ares rocket may be canceled for an alternative heavy-lift vehicle, right now Ares is the program of record, and NASA engineers aren’t holding anything back.

The Constellation team concluded at a Dec 17 meeting they found a way to fix the potential oscillations, which might originate from the solid-rocket main stage and “sync up” with the natural resonance of the rest of the vehicle. Any new Ares rockets will be updated to include the addition of upper plane C-Spring isolator module and the upper stage fuel tank LOX damper.

“When we discover an engineering risk, like thrust oscillation, we tackle it with full rigor,” said Jeff Hanley, Constellation Program manager. “That’s what this team has done with thrust oscillation. We assumed the worst when the problem was first discovered. The good news is there is no empirical evidence of problematic oscillations from our ground test of the first stage development motor or during the Ares I-X first test flight.”

“The isolators work like shock absorbers to de-tune the vehicle and the LOX damper will counter the vehicle acoustic response by absorbing and disrupting the oscillation. Together these options will give us added confidence in the tuning of the vehicle as we mature the Ares and Orion designs,” Hanley said.

On the NASA Blog, the Constellation team said that they, along with the prime contractors, have “worked this issue carefully, understanding and minimizing any effects of the integrated vehicle response by introducing new thrust oscillation hardware into the design. The team will “scar,” or prepare, the upper stage design to accommodate the addition of this mitigation hardware at a later time, if desirable.”

“The options approved today puts us on a robust foundation as we move forward,” said Hanley. “Finalizing the thrust oscillation design now allows us to keep to our schedule and provides contractors specific requirements about what we need them to build.”

Source: NASA Blog

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