Groen Proof-of-concept / Hawk 1 / H2X / Hawk III
Following the successful flight of a proof-of-concept aircraft in 1987, the Groens designed, manufactured and flew several prototype test gyroplanes of increasing size and sophistication during the 1990s.
Based on proof-of-concept Hawk One (N4379X) first flown 26 September 1992; design started April 1996 and prototype two-seat H2X (N4412X) first flew 4 February 1997. The H2X was later converted to three-seat Hawk III standard. The Hawk III multipurpose cabin gyroplane was capable of vertical (jump) take-off. First deliveries had been due June 1998, but design changes to H2X and later Hawk III in October 1998 resulted in Hawk 4.
Engine: one 335kW Geschwinder V-8 aluminium liquid-cooled engine, derated to 261kW at 2.500rpm
Propeller: Hartzell three-blade constant-speed.