TYPE: Convertiplane.

PROGRAMME: Response to request of US Defense Advanced Research Projects Agency (DARPA) for proposals to meet requirement for Advanced Maneuver Transport (AMT) with VTOL and heavy lift capability. Proposal is based upon the integration of a large-diameter rotor powered by tipjets with an existing fixed-wing turboprop freighter. Groen is proposing to DARPA that it be designated to undertake the necessary research and development to produce an intermediate scale technology demonstrator leading to full-scale prototype based on the Lockheed C-130 aircraft.

DESIGN FEATURES: Heavy lift gyrodyne with tipjets for rotor drive; large fuselage with passenger accommodation and rear freight doors; VTOL capability; four turboprop engines; stub-wings to share flight load, to reduce rotor speed and increase aircraft airspeed; and mostly composites construction with metal engine attachments. Complete cargo handling system. Tipjets provide a highly efficient power/weight ratio to enable vertical take-off and landing with a 18,144 kg (40,000 lb) payload, but are shut down in other flight modes, permitting the aircraft to achieve a range of up to 1,000 n miles (1,850 km; 1,150 mile) using the efficiencies of turboprop operation in cruise. Rotor system incorporates five mission-adaptive blades incorporating Westland BERP (British Experimental Rotor Programme) paddle blade tips, which optimise rotor performance during all flight regimes, thereby increasing airspeeds above that of any contemporary helicopter, while reducing fuel consumption.

FLYING CONTROLS: Fly-by-wire, fully integrated flight, engine tipjet and rotor management system.

STRUCTURE: Mainly composites structure for fuselage and wings, and metal inserts for landing gear and engine mounting points. Composites rotor blades and unique rotor head design.

LANDING GEAR: Tricycle retractable landing gear with steerable dual-wheel nose landing gear and bogie-type main gear.

POWER PLANT: One Rolls-Royce AD2100 or Rolls-Royce AE 1107 ะก upgraded from 4,586 kW (6,150 shp) to about 6,711 kW (9,000 shp). Fuel capacity 11,340 kg (25,000 lb).

ACCOMMODATION: Pilot and navigator; or two pilots plus loadmaster.

SYSTEMS: Electrical and hydraulic systems, including APU.

AVIONICS: Fully integrated battlefield systems.

All data are provisional.


  • Rotor diameter: 34.14 m (112 ft 0 in)
  • Rotor blade chord: at root: 1.82 m (5 ft 11½ in)
    • at tip before BERP: 1.21 m (3 ft 11½ in)
  • Length of fuselage: 33.53 m (110 ft 0 in)
  • Height: overall: 7.62 m (25 ft 0 in)
    • to top of fuselage: 5.64 m (18 ft 6 in)
  • Wheel track: 5.18 m (17 ft 0 in)
  • Wheelbase: 12.80 m (42 ft 0 in)
  • Passenger doors (each):
    • Width: 1.22 m (4 ft 0 in)
    • Height to still: 1.07 m (3 ft 6 in)


  • Cabin; Length: 12.50 m (41 ft 0 in)
  • Max width: 4.05 m (13 ft 3½ in)


  • Rotor disc: 914.8 m² (9,847.0 sq ft)
  • Verical tails (total): 40.13 m² (432.0 sq ft)
  • Horizontal tail: 57.6 m² (620.0 sq ft)


  • Weight empty: 24,948 kg (55,000 lb)
  • Max T-O weight: 59,875 kg (132,000 lb)

PERFORMANCE (estimated):

  • Never-exceed speed (VNE): 270-330 kt (500-611 km/h; 310-379 mph)
  • Cruising speed at 75% power: 250-300 kt (463-556 km/h; 288-345 mph)
  • Max rate of climb at S/L: 366 m (1,200 ft)/min
  • Service ceiling: 5,486 m (18,000 ft)
  • Take-off and landing run (powered rotor in gyroplane mode): zero
  • Range at 75% power: 500-1,000 n miles (926-1,852 km; 575-1,150 miles)