Boeing concept

The US Defense Advanced Research Projects Agency (DARPA) will review conceptual designs of the four vertical take-off and landing experimental aircraft (VTOL X-Plane) models in July.

Boeing Phantom Swift programme manager Brian Ritter told IHS Jane’s that the initial reviews of designs developed by Aurora Flight Sciences, Boeing, Karem and Sikorsky are scheduled to be undertaken at the end of next month.

The preliminary design review will be carried out by the end of 2015.

Announced in early 2013, the VTOL X-Plane programme is a 52-month programme aimed at developing and flying an experimental aircraft capable of exceeding 300kt and having hover efficiency of 75%.

"The initial design contracts worth $47m were awarded in March to Aurora Flight Sciences, Boeing, Karem Aircraft and Sikorsky."

DARPA envisages the X-Plane to have useful load capacity of 40% of the vehicle’s gross weight, cruise lift-to-drag ratio of ten or more and twice the aerodynamic efficiency of the existing VTOL aircraft.

The plane is projected to weigh 10,000-12,000 pounds.

Prime contracts for Phase I of the programme were awarded in March to Aurora Flight Sciences, Boeing, Karem Aircraft and Sikorsky.

Boeing’s model Phantom Swift features two large lift fans that provide vertical lift and smaller ducted fans on the wingtips that provide forward thrust, and additional lift and control in hover.

Ritter said that the combination of body-fans and tilt-wing fans for improved controllability is the unique feature of Phantom Swift.

"In the challenge of efficient hover and high-speed flight the answer is in ducted-fan technology, and this is something that Boeing is now investing heavily in," Ritter said.

All the entrants are developing unmanned platforms for the programme, reported Jane’s.

The three-phase programme has been allocated a budget of $130m; the Phase I contracts were worth $47m.

Phase II will include design, development and integration of the aircraft while flight-test demonstrations will be undertaken in Phase III by February 2018.

Image: An artist’s concept of Boeing’s VTOL X-Plane. Photo: courtesy of DARPA.

Defence Technology