The Defense Advanced Research Projects Agency (DARPA) has advanced Bell Textron Inc. to a critical new stage in its Speed and Runway Independent Technologies (SPRINT) program. For Phase 2, Bell is tasked with the detailed design, construction, and ground testing of a revolutionary X-plane demonstrator, moving the concept from the drawing board to the runway.
The ambitious goal of the SPRINT program is to shatter traditional limitations of vertical lift aircraft. The envisioned X-plane must seamlessly combine the high-speed cruise performance of a conventional aircraft with the agile hovering capabilities of a helicopter. Specifically, it aims to operate at blistering speeds of 400 to 450 knots while maintaining the ability to take off and land vertically on unprepared, rough-terrain surfaces.
A cornerstone of Bell’s design is its proprietary “stop/fold” rotor technology. This innovative system allows the large main rotors used for vertical lift and low-speed flight to be stopped and stowed for streamlined high-speed cruise, a feature Bell calls “first-ever.” This technological leap is the culmination of over a decade of research and builds upon the company’s nearly 90-year legacy of pioneering VTOL aircraft, including the iconic XV-15 and the barrier-breaking X-1.
“This selection is a testament to our team’s sustained innovation in high-speed vertical lift,” said Jason Hurst, Bell’s senior vice president of Engineering. “We are excited to demonstrate a transformative capability that will provide future warfighters with unprecedented speed and operational flexibility.”
To de-risk the program, Bell has already successfully demonstrated key technologies. These include rigorous wind tunnel testing at the National Institute for Aviation Research and validation of the folding rotor and integrated propulsion systems at Holloman Air Force Base. With Phase 2 now underway, the path is clear for the ultimate objective: a flight test campaign in the subsequent Phase 3 to prove the aircraft’s revolutionary capabilities.
