On Monday, March 9, 2026, the U.S. Defense Advanced Research Projects Agency (DARPA) revealed that the high-speed unmanned and crewed tiltrotor being developed under the SPRINT (Speed and Runway Independent Technologies) program has received the designation X-76.
Crewed variant / Images: DAPRA
Interestingly, the X-76 designation is not accidental – it coincides with the 250th anniversary of U.S. independence, celebrated this year, and therefore directly references the year 1776.
At the same time, it was announced that the contractor selected on July 9, 2025 for the second phase of the program, Bell Textron, has completed the Critical Design Review (CDR) and has begun construction of a technology demonstrator to validate the chosen technical concept (the competing proposal from Aurora Flight Sciences was rejected).
The goal of the program is to develop an aircraft with a cruise speed comparable to that of conventional airplanes, ranging from 400 to 450 knots (approximately 740–830 km/h) at appropriate altitudes, while remaining independent of runways thanks to the ability to perform vertical or short takeoffs and landings (VSTOL) from unprepared surfaces, similar to a helicopter.
During Phases 1A and 1B, Bell Textron completed conceptual work and preliminary design activities.
“For too long, the runway has been both an enabler and a tether, granting speed but creating a critical vulnerability,” said Cmdr. Ian Higgins, U.S. Navy, serving as the DARPA SPRINT program manager. “With SPRINT, we’re not just building an X-plane; we’re building options. We’re working to deliver the option of surprise, the option of rapid reinforcement, and the option of life-saving speed, anywhere on the globe, without needing any runway.“
After Phase 2, a flight test program in Phase 3 will follow, planned to begin in early 2028. The target platform may ultimately perform missions for the U.S. Special Operations Command (SOCOM), which is the military partner in the program.
Uncrewed variant
As part of the SPRINT program, Bell Textron conducted evaluations of the Stop/Fold rotor concept, integrated propulsion, and flight-control technologies at the HHSTT (Holloman High Speed Test Track) test facility in New Mexico. The company also carried out wind tunnel testing of a model at the NIAR (National Institute for Aviation Research) at Wichita State University.
Bell Textron proposed the use of a hybrid aircraft technology known as HSVTOL (High-Speed Vertical Take-Off and Landing), which can be either crewed or unmanned and combines features of a tiltrotor propulsion system and a jet aircraft. The HSVTOL technology merges the hovering capability of a helicopter with the speed, range, and survivability of jet aircraft.
The HSVTOL concept was unveiled on August 2, 2021, and was developed at the request of the U.S. Air Force. The aircraft would be equipped with two turboprop engines for vertical takeoff and landing (it is not yet clear whether these would use tilting nacelles as in the V-22 Osprey, or only tilting rotors as in the V-280 Valor / MV-75) and a pair of turbojet engines for horizontal flight (during which the turboprop blades would be folded into a horizontal position).
In the case of the SPRINT X-plane, Bell’s new concept for the unmanned variant features redesigned air intakes on the sides of the fuselage and the addition of two air intakes on the upper surface, likely to increase lift during vertical flight or low-speed horizontal flight. Overall, the fuselage is more streamlined, and the turboprop engine nacelles have been slightly modified, presumably as a result of experience gained during testing at HHSTT. Even more changes are visible in the crewed variant, in which the upper fuselage air intake has been removed and the turboprop engine nacelles have been completely redesigned.
Introducing our latest X-Plane, the X-76! ⚡
Part of a joint effort with @USSOCOM on the SPRINT program, this experimental aircraft is being built by @BellFlight to demonstrate runway-independent, high-speed flight. pic.twitter.com/hBnDzjcHAO
— DARPA (@DARPA) March 9, 2026
Bell is thrilled to announce it has completed the Critical Design Review (CDR) for @DARPA's SPeed and Runway INdependent Technologies (SPRINT) X-plane program, enabling Bell to begin building the next-generation aircraft, designated as the X-76.
Learn More:… pic.twitter.com/uk2UdlwY8A
— Bell (@BellFlight) March 9, 2026