GEN H-4

The GEN H-4 is a Japanese 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 115 kg. The aircraft has a standard empty weight of 70 kg. 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, 10 hp 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 4 m. 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 70 kg and a gross weight of 220 kg the H-4 has a useful load of 150 kg. With full fuel of 19 L the payload is 136 kg.

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, 10 hp 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, 40 m to the northwest and then impacted the ground. The pilot was injured and the airframe damaged.