Bell has completed the Critical Design Review for DARPA’s SPRINT programme, clearing the way for construction of the X-76 aircraft demonstrator.

PROGRAMME MILESTONE CLEARS PATH FOR X-76 DEVELOPMENT

Bell Textron Inc. has completed the Critical Design Review (CDR) for the Defence Advanced Research Projects Agency (DARPA) Speed and Runway Independent Technologies (SPRINT) programme. The milestone allows the company to begin building the next-generation aircraft demonstrator, which has been designated the X-76.

The SPRINT programme is jointly funded by DARPA and U.S. Special Operations Command and is intended to advance technologies that enable aircraft to operate independently of conventional runways.

According to Bell, the demonstrator aircraft is designed to cruise at speeds between 400 and 450 knots while maintaining the ability to hover and operate from austere or unprepared surfaces.

SPRINT PROGRAMME MOVES INTO BUILD PHASE

The programme has progressed through several development stages. During Phase 1A and Phase 1B, Bell completed conceptual and preliminary design work for the SPRINT X-plane.

Following the completion of the Critical Design Review, the programme will now move into Phase 2, which includes detailed design, construction and ground testing of the demonstrator aircraft. Flight testing is expected to follow in Phase 3 of the programme.

Bell was selected for Phase 2 in July 2025 after being down-selected in the programme’s competitive evaluation process.

NEW TECHNOLOGIES UNDER DEVELOPMENT

The demonstrator will incorporate new technologies intended to enable high-speed vertical lift capability, including stop/fold rotor technology, which forms part of the programme’s objective to combine vertical take-off and landing with higher cruise speeds.

Prior to entering the build phase, Bell conducted risk-reduction activities that included demonstrations of folding rotor systems, integrated propulsion and flight-control technologies, as well as wind-tunnel testing at the National Institute for Aviation Research (NIAR) at Wichita State University.

CONTINUING THE X-PLANE LEGACY

Bell noted that the SPRINT programme builds on the company’s long involvement in experimental aircraft development. Historically, Bell has contributed to several experimental and high-speed vertical lift programmes, including the X-14, X-22, XV-3 and XV-15 aircraft.

The company says the new X-76 demonstrator represents the next step in developing runway-independent aircraft capable of combining vertical lift with higher cruise speeds.