US military officials have lost contact with the fastest plane ever built during a hypersonic test flight over the Pacific on Thursday.
The Falcon HTV-2 was launched aboard a rocket from Vandenberg air force base in California, on what at first appeared to be a flawless mission.
But after separating from the rocket at the edge of space and beginning its return to Earth, the aircraft went silent during the gliding stage of the test flight, when it was due to perform a series of manoeuvres as it hurtled through the atmosphere.
Falcon HTV-2 is an unmanned, rocket-launched, maneuverable aircraft that glides through the Earth’s atmosphere at incredibly fast speeds—Mach 20 (approximately 13,000 miles per hour). At HTV-2 speeds, flight time between New York City and Los Angeles would be less than 12 minutes. The HTV-2 vehicle is a “data truck” with numerous sensors that collect data in an uncertain operating envelope.
Mastery of three key technical challenges stands between the DoD and long-duration hypersonic flight: Aerodynamics; Aerothermal effects; and critical guidance, navigation and control.
HTV-2 flew its maiden flight on 22 Apr 2010, collecting nine minutes of unique flight data, including 139 seconds of Mach 22 to Mach 17 aerodynamic data.
The second and final planned flight test is scheduled for August 2011. First flight lessons learned, high-speed wind tunnel testing and computer simulations were used to improve aerodynamic models and to optimize the vehicle design and trajectory for flight two.
The goal of the second flight is to validate current assumptions and increase technical understanding of the hypersonic flight regime. More than 20 test assets will collect continuous flight data to achieve this goal.
The second test flight began with launch at 0745 Pacific Time. The Minotaur IV vehicle successfully inserted the aircraft into the desired trajectory. Separation of the vehicle was confirmed by rocket cam and the aircraft transitioned to Mach 20 aerodynamic flight. This transition represents a critical knowledge and control point in maneuvering atmospheric hypersonic flight. More than nine minutes of data was collected before an anomaly caused loss of signal. Initial indications are that the aircraft impacted the Pacific Ocean along the planned flight path.
“Prior to flight, the technical team completed the most sophisticated simulations and extensive wind tunnel tests possible. But these ground tests have not yielded the necessary knowledge. Filling the gaps in our understanding of hypersonic flight in this demanding regime requires that we be willing to fly,” said DARPA Director Regina Dugan. “In the April 2010 test, we obtained four times the amount of data previously available at these speeds. Today more than 20 air, land, sea and space data collection systems were operational. We’ll learn. We’ll try again. That’s what it takes.”