Sometime this afternoon (BST), the HTV-2 will be launched from the Vandenberg Air Force Base in California and will fly over the Pacific Ocean reaching peak speeds of Mach 20 or 13,000mph (20,900km/h), while experiencing temperatures of around 2,000ºC on its carbon-composite body.
HTV-2 is part of a project that started back in 2003 aimed at designing and building a strike capability that could reach any point on the Earth within 60 minutes from a US launchpoint. Now, scaled back somewhat, the remit of the project is primarily focused on data gathering.
‘We need to increase our technical knowledge to support future hypersonic technology development,’ said Dave Neyland, director of DARPA’s Tactical Technology Office.
‘The test will gain further insight into extremely high Mach regimes that we cannot fully replicate on the ground,’ added Major Chris Schulz, HTV-2’s programme manager.
The HTV-2 is packaged in a special capsule atop the launch-ready Minotaur IV Lite rocket. After the Minotaur rocket launches and nears orbit, HTV-2 will separate and fly at a hypersonic glide trajectory within the Earth’s atmosphere.
During the first test flight in April 2010, the HTV-2’s onboard system detected an anomaly and aborted the flight after around nine minutes with a controlled descent into the ocean.
Nevertheless, DARPA said that during the inaugural flight, important data were collected on high lift-to-drag aerodynamics; thermal protection systems; autonomous flight-safety systems; and advanced guidance.
’To have captured the equivalent aerodynamic data from flight one at only a scale representation on the ground would have required years, tens of millions of dollars, and several hundred impulse tunnel tests,’ Schulz said.
Neyland added: ’We gained valuable data from the first flight, made some adjustments based on the findings of an engineering review board to improve this second flight, and now we’re ready to put all of that to the test.’