GRAHAM WARWICK / WASHINGTON DC
Frontier Systems is preparing to fly its A160 Hummingbird, an unmanned rotorcraft with variable-speed rigid rotor which promises far greater range and endurance than conventional helicopters. The aircraft is being developed under a US Defense Advanced Research Projects Agency (DARPA) technology demonstration contract.
The Hummingbird is a 10.7m (35ft)-long vehicle with a 9.8m-diameter main rotor. Its three blades have more in common with aircraft wings than helicopter rotors, according to Irvine, California-based Frontier. Convent-ional rotors have narrow and flexible blades to minimise the transmission of vibration to the fuselage. The Hummingbird has stiff blades and a rigid hub.
In a conventional helicopter, the rotor must always operate at maximum speed to impart sufficient rigidity to the blades. In the A160, the rigid blades allow the rotor to be slowed in flight, reducing vibration and tip speed, and increasing efficiency. An operational vertical take-off and landing unmanned air vehicle (VTOL UAV) based on the Hummingbird is expected to have a range of up to 3,700km (2,000nm) and an endurance of 24-48h.
The A160 is being demonstrated under DARPA's Hummingbird Warrior and Future Combat Systems (FCS) programmes. Hummingbird Warrior is a programme to demonstrate technology for VTOL UAVs capable of reconnaissance and surveillance, communications relay, weapons delivery, crew recovery and special forces operations.
Under the FCS programme to develop concepts for future lightweight, highly mobile manned and robotic fighting vehicles, the A160 would deploy unattended ground sensors, unmanned ground vehicles and micro air vehicles, then loiter for extended periods to relay data back to the command and control components of the FCS.
DARPA's plans call for integration of an electro-optical/infra-red surveillance payload on to the A160, and a synthetic aperture radar/ground moving target indication radar.
Frontier has been flight testing the A160's avionics on a small commercial helicopter converted to a VTOL UAV. Dubbed the Maverick, the vehicle has an endurance of up to 8h and can carry a 180kg (400lb) payload. Mavericks have accumulated almost 250h testing and are attracting attention from potential customers interested in the vehicle's capability and low cost, the company says.
Source: Flight International
