NASA's Slender New Rocket to be Tested for Stability Before Launch

The first flight test of NASA's new rocket configuration to carry astronauts into space will take place later this year. Ares I-X consists of a four-segment first stage solid rocket motor, and a simulated upper stage that represents the weight and shape of the Ares I rocket and Orion crew vehicle. It will be launched in a suborbital arc into the Atlantic to collect data on its flight dynamics and parachute recovery performance.

The flight of the unpiloted Ares I-X will be an important step in confirming that the rocket design is safe and stable in flight before piloted flights of Ares I begin in the middle of the next decade.

But -- even before the launch of Ares I-X -- a critical series of ground tests will take place to confirm that the vehicle's dynamic response will respond to launch loads and vibrations the way that computer analytical models have predicted it will respond.

"While we are confident in the predicted model results and simulations, these ground tests are critical because we have no experience launching rockets as long and slender as Ares I-X," according to Paul Bartolotta, Ares I-X Modal Test Lead who is responsible for leading a NASA-wide Modal Test Team from his office at NASA's Glenn Research Center, Cleveland, Ohio.
The test series is a joint effort between NASA Glenn; NASA's Langley Research Center, Hampton, Va.; NASA's Marshall Space Flight Center, Huntsville, Ala.; and NASA's Kennedy Space Center, Fla.

At approximately 14 feet in average diameter and 320 feet long, Ares I-X has a high "slenderness ratio" compared to other launch vehicles. The similarly-shaped Delta IV, for instance, is about 17 feet in average diameter and 225 feet long. The Saturn V was about 33 feet in average diameter and 363 feet in length.

Due to its long slender shape, the Ares I-X is unique from a flight dynamics standpoint.

"We're going to be shaking the vehicle to make sure our structural models match the actual vehicle characteristics," said Kurt Detweiler, Ares I-X Lead Systems Engineer, based at NASA Langley. "This is important for determining how the vehicle will respond during flight. If the vehicle doesn’t match the analytical model, its guidance, navigation and control systems will be off," he added.