Bell has released a video showcasing its High Speed Vertical Takeoff and Landing (HSVTOL) technology in action. The two-minute video features a ground test of the nacelle system used to take off and land VTOL X-planes before transitioning to jet flight.
As part of DARPA’s SPRINT X Aircraft Program of Independent Speed and Runway Technologies, Bell conducted tests at Holloman Air Force Base in New Mexico to demonstrate how a rotorcraft can transition from rotor propulsion to jet propulsion for horizontal high-speed flight.
In the video, the turbine-powered rotors on the runway-mounted test station are energized and apply thrust as they would in a takeoff situation similar to what would be seen in a tilt-engine aircraft like the Osprey. However, unlike such aircraft, the X-plane in proper flight would tilt its rotor horizontally for forward flight.
Once the aircraft reaches sufficient speed, the jet propulsion system should take over. That’s all well and good, but it now means that the rotors become nothing more than a liability, acting as brakes while increasing drag. To prevent this, the rotors are designed to be washed, then folded and locked into place.
When fully developed, the new pilot-optional aircraft is expected to be able to cruise at high subsonic speeds of up to 450 knots (518 mph, 833 km/h) at a range of 200 nm (230 mi, 370 km) at altitudes of up to 30,000 feet (9,100 m) while carrying a payload of up to 5,000 lb (2,300 kg) in a compartment large enough to accommodate a small vehicle. The aircraft’s purpose will be to provide runway independence for missions ranging from special forces deployment to disaster relief in inaccessible areas.
“The successful completion of the sled test is the culmination of Bell’s unprecedented HSVTOL technology research and development,” said Jason Hurst, executive vice president, engineering. “The technology demonstration provides Bell with critical experience and knowledge that will inform our development of the X-plane for DARPA’s SPRINT program.” It is a key step in creating the next generation of fast vertical lift aircraft for future warfighters.”