NASA - National Aeronautics and Space Administration

The first flight attempt of the X-43A was in June of 2001. Unfortunately, the booster failed and had to be destroyed early in flight. As a result, the research vehicle was not tested because it never reached test conditions. Although no single contributing factor was found, the root cause of the problem was identified as the booster's flight control system. The booster failed due to inaccurate design models that overestimated the capability of the flight control system to operate within predicted flight conditions.

Numerous actions were taken in response to the findings. Wind tunnel tests were conducted to provide data to reduce atmospheric loads on the booster's control surfaces, more powerful booster fin actuators were added to overcome aerodynamic loads, and propellant was machined out of the Pegasus booster to enable launch at its normal launch altitude of 40,000 feet instead of 23,000 feet -- as on the first flight -- in order to reduce aerodynamic loads.

Image above: The Hyper-X program has significantly expanded the boundaries of air-breathing flight by being the first to fly a scramjet-powered aircraft at hypersonic speeds. Credit: NASA

FS-2006-01-118-LaRC
NASA Langley Research Center