AgustaWestland and Airbus Helicopters have submitted next-generation fast rotorcraft demonstrator proposals as part of the European Union’s Clean Sky 2 program — the follow up to the Clean Sky public-private partnership research program.
The European Union is providing €€1.8 billion ($2.45 billion) of funding, to be combined with at least €2.2 billion ($2.99 billion) of private capital, for Clean Sky 2 — which is envisioned as the natural continuation of the technological progress achieved under Clean Sky (set to conclude in 2017). Spanning 2014 to 2024, Clean Sky 2 is looking to develop a higher level of integration of the technologies created under the original program. Clean Sky 2 is split into three different vehicle streams: large passenger aircraft, regional aircraft, and fast rotorcraft — chosen to meet the perceived market opportunities of the future.
The preliminary program outline for Clean Sky 2 said: “The helicopter architecture can be [considered] as nearly ideal for vertical flight, but restricts dramatically its lifting and propulsive efficiency in forward flight beyond 150 to 160 knots, when intrinsic aerodynamic limits of current designs are approached.” The report said non-conventional rotorcraft architectures that feature a fixed wing to unload the rotor at very high speeds offer an attractive alternative. “Research aimed at high-speed rotorcraft architectures showed that the tiltrotor aircraft, where prop-rotors can be tilted from vertical (for hovering) to horizontal for high-speed forward flight, and the compound aircraft, where one or several propellers provide forward thrust and enables a high horizontal speed, are viable solutions to overcome current helicopter limits.”
As such, AgustaWestland has been tasked with developing a next generation civil tiltrotor demonstrator (based on its AW609), and Airbus Helicopters encouraged to build on the success of its X3 hybrid demonstrator.
AgustaWestland’s proposal will be dedicated to validating an innovative tiltrotor configuration that goes beyond the current architectures of the aircraft type. The manufacturer is aiming for a cruise speed in excess of 300 knots, while reducing CO2 emissions by 17 percent, and cutting noise by 20 percent. The program outline requested a wing and airframe structure that hosts a tiltable engine nacelle (as the AW609 does today), but also includes a tiltable portion of the wing itself, allowing for greater performance and efficiency. The proposed program schedule would see a critical design review in 2016, followed by a first flight in 2019.
Airbus Helicopters said its compound aircraft design, titled LifeRCraft, will have a cruise speed of up to 220 knots, and have lower noise and CO2 emissions than a helicopter. The central fuselage is optimized for high speed with low drag, and has access at the rear of the aircraft through a ramp. The wing has large flaps, with concept artwork showing two possible positions for its two propellers — fore and aft of the wings. The program schedule would see a critical design review in early 2017, with flight/operation demonstration activities taking place from 2019 to 2020.
“Fast rotorcraft platforms will provide more speed, longer range, more ‘productivity’ . . . and will make new and more efficient and effective services to citizens,” the program outline stated. “It is expected that combining private industrial investments with substantial and focused public funding on R&T and technology validation, will permit [the] E.U. to maintain the current leadership in the sector at both integration and system level, even in this new emerging field of fast rotorcraft.”
