Sikorsky has successfully completed vertical-to-forward flight transitions of its autonomous rotor-blown-wing demonstrator, an all-electric aircraft the company is using to better understand the complexity of such manoeuvres.
The milestone was achieved in January when flying the vertical take-off and landing (VTOL) aircraft from Naval Air Station Patuxent River’s Webster Field in Maryland, the company said on 10 March.
It has since completed 40 flights, including “30 transitions between helicopter and airplane modes, the most-complex manoeuvre demanded of the design”.
“Our rotor-blown-wing has demonstrated the control power and unique handling qualities necessary to transition repeatedly and predictably from a hover to high-speed wing-borne cruise flight, and back again,” says Igor Cherepinsky, director of Sikorsky Innovations, the company’s rapid-development division.
“New control laws were required for this transition manoeuvre to work seamlessly and efficiently. The data indicates we can operate from pitching ship decks and unprepared ground when scaled to much larger sizes.”
The demonstrator has two propellers and a 3.1m (10.3ft) wingspan. It weighs 52kg (115lb) and can carry a 9kg payload.
“In just over a year, Sikorsky Innovations has progressed through preliminary design, simulation, tethered and untethered flight to gather aerodynamic, flight control and quality data,” Sikorsky says.
Also known as a tail-sitter and a flying wing, the rotor-blown wing takes off vertically with lift from its propellers and then transitions into forward wing-borne flight. Sikorsky developed the demonstrator to study aerodynamics associated with that manoeuvre.
“Combining helicopter and airplane flight characteristics onto a flying wing reflects Sikorsky’s drive to innovate next-generation VTOL [unmanned] aircraft that can fly faster and farther than traditional helicopters,” says Sikorsky vice-president and general manager Rich Benton.
The company envisions larger variants of the design as being useful for missions involving search and rescue, humanitarian response, surveillance and reconnaissance.
The rotor-blown wing is among several designs under review by Sikorsky as part of its broader evaluation of hybrid-electric propulsion and automation. It is also developing a hybrid-electric tiltwing demonstrator, and has concepts on the books for two possible hybrid-electric-powered production aircraft: a 9-12-passenger tiltrotor and a helicopter dubbed e-76.
