The GEN H-4 is a Japanese ultralight coaxial helicopter under development by GEN Corporation of Nagano. The aircraft is intended to be supplied as a kit for amateur construction.

Design and development

The H-4 was designed to comply with the United States FAR 103 Ultralight Vehicles rules, including the category's maximum empty weight of 115kg (254lb). The aircraft has a standard empty weight of 70kg (154lb). It features two contra-rotating main rotors, a single-seat open cockpit without a windshield, four-wheeled landing gear and four twin-cylinder, air-cooled, two-stroke, 10hp (7kW) GEN 125-F engines to provide operational redundancy since the aircraft cannot autorotate in the event of a power failure.

The aircraft fuselage is a simple open frame with a seat mounted on it. Its two coaxial, contra-rotating two-bladed rotors have diameters of 4m (13.1ft). The main rotors are both of fixed pitch design, with no articulation in any axis. Steering is accomplished by pivoting the rotor head on a gimbal using a control handle, in a similar manner to a weight shift hang glider. Climb and descent is controlled by increasing and decreasing the throttle. The aircraft lacks a tail rotor, as the coaxial, contra-rotating main rotors produce zero net torque. Yawing motion is produced and controlled by electronic gyroscopically-controlled differential electric braking of the main rotors. With its empty weight of 70kg (154lb) and a gross weight of 220kg (485lb) the H-4 has a useful load of 150kg (331lb). With full fuel of 19 litres (4.2impgal; 5.0USgal) the payload is 136kg (300lb).

The company indicated that it had suspended production plans by 2012 due to lack of dealers outside Japan and put the cost of a single H-4 at ¥7,500,000.00 (about US$80,887.59 in 2013). The company stated that it could build the aircraft economically only in lots of ten and at a discounted rate only in lots of one hundred. To facilitate future production, the company indicated that it was "looking for sponsors, investors and partners".

Variants

H-4

Initial model powered by four twin-cylinder, air-cooled, two-stroke, 10hp (7kW) GEN 125-F engines

H-4E

Electrically-powered model under development

H-4R

Remote-control model under development

Accidents

On 29 June 2000, the prototype H-4, registered JX0076, was on a test flight at the company plant in Matsumoto-City, Nagano. The pilot was hovering, when the H-4 was hit by a wind gust and contacted the building, 40m (131ft) to the northwest and then impacted the ground. The pilot was injured and the airframe damaged.

Specifications (H-4)

Data from Bayerl, Tacke and helistart.com

General characteristics

  • Crew: one
  • Empty weight: 70kg (154lb)
  • Gross weight: 220kg (485lb)
  • Fuel capacity: 19 litres (4.2impgal; 5.0USgal)
  • Powerplant: 4 × GEN 125-F two-cylinder, air-cooled, two-stroke engines, 7.5kW (10hp) each
  • Main rotor diameter: × 4m (13ft 1in)

Performance

  • Maximum speed: 200km/h (120mph, 110kn)
  • Cruise speed: 100km/h (62mph, 54kn)
  • Range: 80km (50mi, 43nmi)
  • Service ceiling: 3,000m (10,000ft)
  • Rate of climb: 4m/s (790ft/min)

External links