The Bensen X-25

The gyroplane (or "gyrocopter" or simply "gyro") is a helicopter-airplane hybrid, offering many of the benefits of both and several of its own. Unlike a helicopter, the gyro's rotor blades are unpowered, necessitating a short roll for take-off. A major safety feature of the gyro is that if the engine fails, the craft can glide to a safe landing. Also, the gyro is less affected by high wind than typical fixed-wing aircraft and is not subject to stall. History was made in 1924 when Lt. Juan Gomez-Spencer made a flight in the world's first practical rotary-wing aircraft - the Cierva C.4. Pre-war autogiros (autogiro was a Cierva trade name) were massive aircraft that were expensive to purchase and operate, but they had considerable success in specialized roles such as mail delivery to central cities, news reporting, and the air-show circuit.

In the 1950s the Bensen Aircraft Corporation developed the novel "Gyrocopters" and "Gyrogliders." The B-7 Gyroglider, introduced in 1955, captured the public's imagination with its unprecedented simplicity of design and ease of flight. Although the B-7 had no engine and was towed into the air very much like a kite, shortly thereafter the engine-powered B-7M Gyrocopter was introduced. Bensen founded the Popular Rotorcraft Association in the 60's and his aircraft dominated the home-built rotorcraft movement into the early 1980's. The Bensen X-25 Discretionary Descent Vehicle [DRV], a revised version of the Bensen Aircraft standard B-8M gyrocopter, was tested as means for downed flyers to escape from enemy territory. The concept called for replacing the standard ejection seat with the DRV, which would enable a pilot forced to eject to fly away from the action in a controlled descent. Designed to operate like a rotorchute, following ejection and a brief period of decent, the DDVs rotor blades automatically self deployed and aerodynamic forces then rotated the blades. It came about as a result of a growing number of pilots being downed beyond the range of conventional rescue methods during the Vietnam War.

The basic X-25 was un-powered and of very basic construction, consisting of little more than an aluminium square cross sectioned structure with a single seat and four post landing gear. The X-25A & B were variations of Bensons McCulloch powered B-8M and un-powered B-8 Gyroglider. Although far more complex than the planned ‘one use’ DDV, the X-25A and B provided both the data required to prove the feasibility of the DDV concept. The X-25A first flew in May 1968 and was proven to be feasible, but production was never funded.

Bensen X-25A "Gyrocopter" Specifications
Rotor Diameter	21 feet, 8 inches
Length	11 feet, 3 inches
Height	6 feet, 9 inches
Weight	247 lbs.
Engine	McCulloch 72 hp, 4 cylinder, 2 stroke piston, air cooled
Maximum speed	85 mph
Cruising speed	60 mph
Range	300 miles
Service Ceiling	12,500 feet

Powered autogyro versions of the auto-kites have been developed simultaneously, the first of these being the B-7M which flew for the first time on 6 December 1955. This was followed on 8 July 1957 by the first B-8M (M = motorised) and by the first production B-8M on 9 October 1957. The Gyro-Copter was a powered version of the Gyro-Glider. It was designed to be constructed from a set of plans costng about $30 or from a prefabricated kit, costing $995. Engines were available ranging in price from $495 to $1195. As few as forty manhours were required for kit assembly. It was designed by Igor Bensen, a Russian immigrant to the United States. He had been a test pilot for both the Air Force and the Navy. His new company was formed to develop light, safe rotary-wing aircraft for use by private individuals. Besides their use as a pleasure craft Gyro-Copters could be used for terrain and pipeline aerial surveillance and sport and forestry patrol. In England one was modified for crop spraying. All three branches of the military had several in their inventories.

The first aircraft produced by the Benson company were the Bensen B-7 and B-8 Gyro-Gliders, which were unpowered and could be flown without a pilot license in the United States. It could be built at home from a kit that an aspiring pilot would purchase from the company or could be purchased already assembled. The "M" in the B-8M is for motorized. The B-7 had no engine and was towed into the air very much like a kite. 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 autogyro was a powered version of the Gyro-Glider and could fit in anyone's garage. The Model B-8M could also be converted from an aircraft to an automobile by simply locking its blades in place. On the road as an automobile it could achieve 35 mph. Production of the Gyrocopter continued until 1987.

The gyroplane (or "gyrocopter" or simply "gyro") is essentially a helicopter-airplane hybrid. Unlike a helicopter, the gyro's rotor blades are unpowered, necessitating a short roll for take-off—unless the craft is fitted with a pre-rotator.

The museum's Benson B-8M was donated on January 19, 1991, by Adeline Weigandt of Huntington Beach, CA.. This aircraft is on loan from the USAF.

Two X-25 aircraft were procured by the USAF in 1968 to test a method for improving the chances of rescuing crewmen forced to bail out from their aircraft over enemy territory. If the flyer had a means of controlling his descent after parachuting and could select a landing site, his chances of avoiding capture would be greatly increased.

The unpowered Bensen X-25B “Gyroglider” theoretically could be deployed after the flyer’s parachute had opened. Its rotary wings would be brought up to speed during the descent, the parachute would be detached, and the “Gyroglider” would then be flown as an autogiro to a landing point.

The X-25A “Gyrocopter” represented a more advanced concept with a limited “fly-away” capability. Unlike the X-25B, which had no engine, the X-25A had a 90 hp engine. Following tests at Wright-Patterson Air Force Base, Ohio, the X-25A was delivered to the museum in 1969.

Bensen X-25A "Gyrocopter"

Specifications