The Defense Advanced Research Projects Agency (DARPA) has released new details about the fate of the Hypersonic Test Vehicle (HTV-2), which crashed into the Pacific Ocean during its 11 August flight.

"An initial assessment indicates that the Flight 2 anomaly is unrelated to the Flight 1 anomaly," said Major Chris Schulz, HTV-2 programme manager.

"We've confirmed that the HTV-2 made impact with the Pacific Ocean along its flight trajectory as planned in the event of an anomaly," Schulz said.

The unpowered glide vehicle was successfully boosted into space by an Orbital Sciences Minotaur IV rocket, and re-entered the atmosphere at M20.0 hypersonic as planned. Three minutes later, the vehicle encountered an as-yet undescribed anomaly and crashed into the Pacific Ocean.

"HTV-2 demonstrated stable aerodynamically controlled M20.0 hypersonic flight for approximately 3min," said DARPA director Regina Dugan. "It appears that the engineering changes put into place following the vehicle's first flight test in April 2010 were effective. We do not yet know the cause of the anomaly for Flight 2."

Flight 1 ended shortly before the 9min mark before encountering unanticipated aerodynamic difficulties that caused it to exceed its flight parameters; its onboard computer automatically directed it into the ocean for safety reasons. As a result several changes were made to the vehicle and its flight path in anticipation of Flight 2.

DARPA has repeatedly declined to release further information in advance of an engineering review board. No date has been set for release of information from the board.

Source: Flight International