In the 1960s, the American company Filper Research, led by William Orr, built an unusual helicopter equipped with “Gyroflex” rotor systems. The novelty of this system was that it used weights, fixed at the base of the blades, for rotor balancing. This concept was first tested on the experimental Filper Helicopter, which consisted of two pylons with rotors and a connecting beam, on top of which the pilot sat and the engine was mounted.
Following this prototype, a commercial variant was built: the Filper Beta 100A. This was a tandem-layout machine with the engine in the front pylon and a two-seat cockpit located in front of the rear pylon. Curiously, in this arrangement, the pilot sat quite far from the nose of the aircraft.
Innovative Design and Early Models
On May 26, 1966, the Filper Beta 200 helicopter took to the air. The company’s designers planned to create several modifications, including two-seater versions (Models 200A and 300) and four-seater versions (Models 400A and 600A), with the four-seater models having a fuselage extended by 0.9 meters. The first four-seater Filper Beta 400A made its maiden flight on July 13, 1967.
Equipped with “Gyroflex Rotor” blades, the aircraft featured engines in the flat front section, while the cockpit was placed in the aft part of the helicopter. It is not entirely clear how convenient this was for piloting or how the machine behaved with changes in longitudinal balance, but it did fly.
Variants and Engine Specifications
The “Beta” helicopters were equipped with various engines. These included the Continental IO-360-E piston engine with 155 kW (for Model 200A), the Allison 250-C18 turboshaft engine (for Model 300), and the Continental IO-520 piston engine with 185 kW (for Model 400A). The engine for Model 600A is unknown.
Production and Company Closure
Registration records indicate that 32 “Beta” helicopters were built, including two Model 100A, 29 Model 400A, and one Model 600A. However, there are doubts as to whether all of them were completed. In 1969, Filper ceased its operations.
Technical Specifications
| Modification | Beta 200 |
| Main rotor diameter, m | 6.22 |
| Length, m | 5.33 |
| Height, m | 2.80 |
| Empty weight | 453 |
| Maximum takeoff weight | 771 |
| Engine type | 1 Piston engine Continental IO-360E |
| Power, hp | 1 x 210 |
| Maximum speed, km/h | 241 |
| Practical range, km | 642 |
| Crew, crew members | 2 |
Image and diagram gallery of the Filper Beta Helicopters
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