DARPA selects Bell Helicopters as second competitor in Phase 1B of SPR…

Bell Helicopters' entry for DARPA's SPRINT contest. (Bell Helicopters)

The US Defense Advanced Research Projects Agency (DARPA) has selected a second competitor for Phase 1B of its Speed and Runway Independent Technologies (SPRINT) programme, the agency announced on 28 May.

Phase 1B is intended to mature Bell Helicopters' design through preliminary design review (PDR). A conceptual image of Bell Helicopters' SPRINT design shows an unmanned, twin-engine tiltrotor aircraft. The tiltrotors are intended to fold into the nacelle, allowing a jet engine embedded in the aircraft's body to take over and propel the craft to high speeds.

“Bell is honoured to be selected for the next phase of this revolutionary programme and ready to execute preliminary design,” said Jason Hurst, the company's executive vice-president of engineering, in a 28 May statement. “We completed our initial risk reduction efforts with our sled test demonstration at Holloman Air Force Base (AFB), and we look forward to building on this success with our continued work with DARPA.”

The company conducted high- and low-speed rotor folding tests at Holloman AFB, Jeff Nissen, Bell Helicopters' High-Speed Vertical Take-off and Landing (HSVTOL) programme manager, told Janes in an 8 February interview.

The sled-testing demonstrated “everything needed in an aircraft except the airframe”, Nissen said. “The folding rotor system, a flight-representative rotor at full scale, a propulsion system, and the flight-control system that controls it all” were tested.

SPRINT's Phase 1B, expected to last one year, is meant to advance designs from conceptual design review through PDR, in which designers detail the component parts and specifications needed for the design.

DARPA selected four companies for Phase 1A of the programme in November 2023: Aurora Flight Sciences, Bell Helicopters, Northrop Grumman, and Piasecki Aircraft Corporation.