First Look at Jet-powered VTOL X-plane After Finishing Wind Tunnel Tests for DARPA SPRINT Program

Bell has completed wind tunnel tests of its X-plane model at the National Institute for Aviation Research (NIAR) at Wichita State University, part of DARPA’s Speed and Runway Independent Technology (SPRINT) program, aimed at creating an aircraft to demonstrate technologies allowing high-speed flight without the need for traditional runways.

According to a press release by the company, the wind tunnel testing comes after successful trials of its Stop/Fold rotor system at the Holloman High-Speed Test Track (HHSTT) in New Mexico in 2023.

The test model shows a streamlined hull with two wing-like structures extending outward symmetrically from either side and compact tilt-rotor nacelles sitting behind aerodynamic fairings. After take-off, the X-plane tilts its rotor nacelles forward for horizontal flight and locks them off when the jet engines work. At this point, the rotor blades become a liability creating drag. To address this, the rotors are designed to fold back into the nacelle.

Bell also said that when the technology demonstrator craft is complete, the aircraft is expected to cruise at high subsonic speeds of up to 450 knots (518 mph, 833 km/h) with a range of 200 nm (230 miles, 370 km) at a height up to 30,000 ft (9,100 m). Not only that, it will also be able to carry payloads of up to 5,000 lb (2,300 kg) in a compartment large enough to hold a small vehicle.

The DARPA SPRINT X-Plane program is set to reshape the future of aviation for the US Armed forces, aimed at making the twain meet in an aircraft that could take off, land, and hover like a rotorcraft and then transform into a jet while being vertically flight. 

The program addresses critical operational gaps for the US Army and Air Force as modern warfare demands unyielding performance from aircraft that serve under fire, in rapid deployability, combat resilience, and mission versatility.

Phase 1A was started in November 2023 to conduct conceptual design reviews. In May 2024, Bell and Aurora Flight Sciences were selected and awarded contracts for Phase 1B to complete preliminary design work for their aircraft in approximately one year.

It will provide increased speed, range, survivability, and maneuverability for special forces, especially in the Indo-Pacific theater, where long distances and limited runways make traditional aircraft operations more difficult.

Image source by Bell Flight