The US Defense Advanced Research Projects Agency (DARPA) is releasing a requirement for a new experimental aircraft, combining the best of vertical take-off and landing technology with conventional aircraft.

The aircraft, one of the rare formally designated X-planes, is meant to both hover and fly at high speeds with efficiency equal to dedicated platforms. Specifications call for an aircraft capable of more than 300kt (555km/h) maximum airspeed; higher than conventional helicopters can achieve, and the ability to hover with greater efficiency than current rotorcraft.

So far, aircraft that have both flown at high speed and operated vertically cannot operate well in either flight profile.

 Amercain Dynamics AD-150 VTOL UAV

 American Dynamics   

 Lockheed Martin concept VTOL UAV

 Lockheed Martin   

UAV concept

DARPA will require the X-plane to both hover and fly at high speeds with efficiency equal to dedicated platforms

"What we're trying to do here is achieve radical and transformational" technologies, says Ashish Bagai, DARPA programme manager. "We're looking to develop vastly improved technologies usable by the community, particularly by [the Department of Defense].

"We're looking at doing this in an elegant fashion, we're not looking for brute force."

The programme, budgeted at $150 million, will have three distinct phases: a first will involve maturing necessary technologies, while phases two and three will involve hardware proving and flight testing. While multiple concepts will be selected, only one will be chosen for flight. DARPA hopes for first flight three and a half years after programme launch.

"I think we have to be a little bit careful about just going back and revisiting what's been tried before," says Bagai. "There is a lot of technology now available to directly address shortcomings" of previous designs, he notes.

Further details, including whether the aircraft will be manned or unmanned, were purposely left vague, which Bagai says is to allow bidders the most creative freedom in designing solutions.

The most recent X-plane, the Lockheed Martin X-56, was built for the Air Force Research Laboratory and NASA to test high-altitude, low-speed airfoil characteristics.

Source: Flight International