From the B-5 Gyro-Glider factory-built prototype of 1954, Bensen evolved the B-6 and B-7, and from these has come the standard production model the B-8.
This has a more sturdy construction and was available as a factory-built machine or in kit form for amateur construction. Two water-borne versions of the B-8 were also available: the B-8B Gyro-Boat which has a boat-type hull and twin outrigged stabilising floats, and the B-8W Hydro-Glider mounted on twin floats.
From the reworked B-7M came the B-8M variant, first flying on 8 July 1957 and by the first production B-8M on 9 October 1957.
The B-8M is normally powered by a 72hp McCulloch piston engine. Optional features include a 90hp McCulloch engine and a mechanical rotor drive enabling the autogyro to make jump starts.
A float version of the B-8M is known as the Hydro-Copter.
The Gyro-Boat is a variant of the Gyro-Glider, in which the basic free-turning rotor system, known as the Roto-sail, is mounted on any standard small dinghy. The result is literally a flying boat, intended to be towed above water by a motor boat.
The two-blade steel and plywood rotor has a diameter of 6.10m and disc area of 29.2sq.m. Each blade has an area of 1.0sq.m. When fitted to a 3.66m aluminium dinghy weighing 45kg, the complete Gyro-boat has an empty weight of 68kg and a loaded weight of 147kg carrying one person or 227kg carrying two people.
It takes off when towed at a forward speed of 37km/h, cruises at 55-110km/h and lands at 11km/h.
The prototype Gyro-Boat flew for the first time on April 25, 1956, and the first production model on July 8, 1956. The 1959 version can be fitted with stabilizing pontoons on outriggers for rough water operation.
Designed for home construction from kits or plans, captured a series of international records in 1967, including an altitude of 7,275 ft (2,717 m) and a speed of 79 mph (127.15 kph) over a 15 km course.
By 1984 there were more than 10,000 active rotorcraft fans in the United States.
With purchase of their plans and component kits, it is possible to build a machine in a few weeks of spare time, with only a drill press and a few wrenches. Bensen Gyrocopters can be towed behind a car or boat or flown under their own power. The simple glider models are available as one or two seaters. The powered gyrocopters are available only as single seaters. The Gyrocopter is capable of climbing to 12,500 feet. The powerplant is a 72- to 90-hp McCulloch.
Price in 1982: $4,850 (Excludes engine). Units delivered to June 1982: 4,000.
The B-8 Gyro-Glider is a simple unpowered rotor-kite which can be towed behind even a small motor car. It is available as either a completed aircraft or kit of parts for amateur construction. Alternatively, would-be constructors can purchase a set of plans, with building and flying instructions. No pilot's licence is required to fly it in the United States and many hundreds of kits and plans have been sold. Application was been made for an Approved Type Certificate.
The original Model B-7 Gyro-Glider was followed by the Model B-8, which is offered as either a single-seater or two-seater, the latter version being suitable for use as a pilot trainer.
The Model B-8 consists basically of an inverted square-section tubular aluminium T-frame structure, of which the forward arm supports the lightweight seat, towing arm, rudder bar and landing gear nose-wheel. The rear arm supports a large stabilising fin and rudder, with the main landing gear wheels carried on a tubular axle near the junction of the T-frame. The free-turning two-bladed rotor is universally-mounted at the top of the T-frame and is operated directly by a hanging-stick control. It is claimed that the entire aircraft can be made from commercial tubing, wood and locally-available materials.
Demonstrated in public for the first time in 1976, the B-8MH Hover-Gyro is described as a 'Hovering Gyro-Copter'. It was powered by a 70-110hp modified water-cooled outboard engine driving the lower of the two rotors; the upper rotor autorotates. One 14 hp modified air-cooled go-kart engine drives the pusher propeller mounted at rear.
B-8 Super Bug
The B-8 Super Bug was a B-8M modification with two engines installed to spin up the rotor prior to take-off.
The B-8HD was a 1979 Gyro-Copter was based on the Super Bug design. It uses hydraulic drive to feed about 4hp from the engine to the rotor, instead of having a separate engine for pre-rotation. This is reported to give the aircraft a take-off run of less than 61m.
Main rotor diameter: 6.1m
Fuselage length: 3.45m
Engine: McCulloch 4318E 4-cylinder, 72 hp
Rotor dia: 20 ft 0 in (6.1 m)
Fuselage length: 11 ft 4 in (3.45 m)
Height: 6 ft 3 in (1.9 m)
Max TO wt: 500 lb (227 kg)
Empty Wt. 247 lbs / 112kg
Fuel capacity 6 USG
Max level speed: 85 mph (137 kph)
Cruising speed: 72km/h
Ceiling: 12,000 ft / 3810m