PAUL LEWIS / WASHINGTON DC
Groen Brothers Aviation (GBA)has unveiled agyrodyne solution to meet the US Army's future need for a vertical take-off landing (VTOL) heavylift transport. GBA's Gyrolifter proposal is for a modified Lockheed Martin C-130 equipped with a tip-jet-driven rotor system.
The C-130 Gyrolifter is in response to a Department of Defense study contract awarded last year to examine different concepts for meeting the army's need for an Advanced Manoeuvre Transport (AMT).
"The primary advantage of a gyrodyne is its simplicity. There is no main transmission, it uses an aircraft that already exists and requires very little change, and it can meet both range and load requirements," says company president David Groen.
Groen's concept is essentially a throwback to the UK's twin-engined Fairy Rotodyne, abandoned in 1962. The Gyrolifter would retain the baseline C-130 fuselage and wing, but with a new empennage with four vertical stabilisers, a rotor head and five composite blades with advanced aerodynamic tips. The rotor would be driven by blade tip combustion air.
The jets will drive the rotor during VTOL and hovering operations only, shutting down and leaving the blades autorotating as the Gyrolifter transitions, forward speed increases and lift is offloaded from the rotor to the wing. High pressure air, either bleed from the gyrodyne's turboprops or generated by compressors, would be fed through a rotating coupling in the rotorhead to the blade tips. Separate pumps would feed jet fuel to the tips for combustion.
Groen claims the concept of converting an existing aircraft design has already been proven using a Cessna Skymaster equipped with a rotor system from the company's Hawk 4 gyroplane and will be extended next to an Antonov An-28. The AMT requirement is to lift a 9,100kg (20,000lb) payload at 300kt (555km/h) over a minimum 925km (500nm) range. Other concepts include Sikorsky's co-axial heavylift helicopter, Bell's Quad Tiltrotor and Boeing's tiltwing Advanced Tactical Transport.
Source: Flight International
