Pentagon fails in quest to fly fastest-ever hypersonic aircraft

12 Aug 2011

A hypersonic experimental plane launched by the Pentagon yesterday aboard a Minotaur IV rocket got lost from its radar after just nine minutes of flying, dashing the US military’s aspiration to fly the fastest aircraft ever built for the moment.

The second test flight of the Falcon Hypersonic Technology Vehicle 2 (HTV-2), which can apparently fly four miles a second, began on Thursday at 07.45 Pacific Time when the Defense Advanced Research Projects Agency’s (DARPA) Minotaur IV rocket put the plane on its designated flight path.

All was initially going well for the arrowhead-shaped aircraft, which had been pioneered to test new hypersonic technologies to give the Pentagon the eventual capacity to deliver non-nuclear military strikes anywhere on the planet in less than 60 minutes. The HTV-2 separated from the rocket before heading into Mach 20 aerodynamic flight, with the aim of flying 13,000 miles per hour.

But – just nine minutes into the 30-minute flight from Vandenberg Air Force Base, north west of Santa Barbara – DARPA said an “anomaly” caused a loss of signal with the hypersonic plane, and its initial suggestion was that the plane plunged into the Pacific Ocean off the coast of Kwajalein Atoll along its planned flight path.

DARPA said on its Twitter account after 20 minutes that “Range assets have lost telemetry with HTV2”.

HTV-2 DARPA hypersonic aircraft designed to fly anywhere in the world in less than 60 minutes

Image of the HTV-2 taken from its April 2010 flight

It’s estimated that the HTV-2 programme, which began in 2003, has cost the US taxpayer around $320m.

The hypersonic test plane, made by Lockheed Martin Corp, has now failed on both flight attempts, the first being in April 2010.

“Here’s what we know,” said Air Force Maj. Chris Schulz, DARPA HTV-2 programme manager, last night. “We know how to boost the aircraft to near space. We know how to insert the aircraft into atmospheric hypersonic flight. We do not yet know how to achieve the desired control during the aerodynamic phase of flight.  It’s vexing; I’m confident there is a solution. We have to find it.”

To manage its aim of flying anywhere in less than 60 minutes, the aircraft would have to have the capability to fly at 13,000 mph, while experiencing temperatures in excess of 3500 degrees fahrenheit.

To give an idea of the speed such a plane could be capable of achieving, the agency said a flight from New York to Los Angeles at Mach 20 would take less than 12 minutes.

“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.

We’ll learn. We’ll try again. That’s what it takes

“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,” added Dugan.

Schulz said three technical challenges exist within this HTV-2 flight regime: aerodynamic; aerothermal; and guidance; and navigation and control. 

He said each phase of flight introduces unique obstacles within these areas. 

High-Mach flight in the atmosphere – “virtually unchartered territory”

To address these obstacles, DARPA has assembled a team of experts that will analyse the flight data collected during the Thursday, 11 August test flight to expand “our technical understanding of this incredibly harsh flight regime,” explained Schulz. 

“As today’s flight indicates, high-Mach flight in the atmosphere is virtually uncharted territory.”

An Engineering Review Board at DARPA will review and analyse the data from the nine-minute flight in the coming weeks.

Main photo: HTV-2 hypersonic test plane, dubbed the ‘Falcon’, which got lost from the Defense Advanced Research Projects Agency’s (DARPA) radar after just nine minutes of flying in the atmosphere above the Pacific Ocean yesterday. The aircraft apparently plunged into the Pacific Ocean off the coast of Kwajalein Atoll. The US military had been pioneering the aircraft since 2003 in its bid to fly anywhere in the world using hypersonic technology in under 60 minutes to launch military strikes. Both images courtesy of DARPA


Carmel Doyle was a long-time reporter with Silicon Republic