Engineering:Bensen B-8

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Short description: Small, single-seat autogyro

B-8
General information
National originUnited States
ManufacturerBensen or homebuilt
Designer
History
First flight6 December 1955[1]

The Bensen B-8 is a small, single-seat autogyro developed in the United States in the 1950s. Although the original manufacturer stopped production in 1987, plans for homebuilders are still available as of 2025. Its design was a refinement of the Bensen B-7, and like that aircraft, the B-8 was initially built as an unpowered rotor-kite. It first flew in this form in 1955, and on 6 December a powered version, designated B-8M (M for motorised) first flew. The design proved to be extremely popular and long-lasting, with thousands of sets of plans sold over the next thirty years.

Design and development

The B-8's design is extremely minimalist, with not much more to the aircraft than a pilot's seat, a single tailfin, a rotor, and (in powered versions) the powerplant. In May 1968 a B-8 and B-8M were studied by the USAF under the Discretionary Descent Vehicle (DDV) program as the X-25B and X-25A respectively. In this scheme, it was proposed to integrate combat aircraft ejection seats with a small autogyro or rotor kite to allow downed pilots more control over their post-ejection landing spot. The X-25A and X-25B were used to evaluate the piloting and training requirements of the autogyros. No full-scale operational tests were ever performed. The U.S. Air Force stopped funding the DDV program with the end of the Vietnam War.[2]


Variants

  • B-8 Gyro-Glider - unpowered rotor-kite intended to be towed behind a car
  • B-8B Hydro-Boat - B-8 with a full boat hull intended to be towed behind another boat
  • B-8M Gyro-Copter - standard motorised version, main production type. Usually powered by a McCulloch 4318 engine
    • B-8MH Hover-Gyro - twin, coaxial rotor design with powered lower rotor and autorotating upper rotor, giving it the capability of hovering. Upper rotor and drive propeller powered by separate engines
    • B-8MJ Gyro-Copter - B-8M modified for "jump" take off by a small second engine providing power to rotor head with anti-torque provided by rudder correction under power.[3]
      X-25A 68-10770 in flight
    • B-8MW Hydro Copter - float-equipped B-8M
    • X-25A - B-8M evaluated by USAF. Single example (serial 68-10770) first flown 5 June 1968 and preserved at the National Museum of the United States Air Force at Wright-Patterson Air Force Base
  • B-8 Super Bug - similar to B-8M but with extra engine to spin up rotor before take-off
    • B-8HD Super Gyro-Copter - development of Super Bug first flown in 1979 with hydraulic drive to pre-rotate rotor rather than separate engine
  • B-8V - B-8 powered by a Volkswagen air-cooled engine
  • B-8W Hydro-Glider - float-equipped B-8 intended to be towed behind a boat[4]
  • X-25B - B-8 evaluated by USAF. Single example (serial 68-10771) first flown 23 January 1968 and preserved at the AFFTC Museum at Edwards Air Force Base.
  • Rotorcraft Minicopter Mk 1 - South African variant with pre-rotator and cockpit fairing.[5]
  • Aeroflyte DGH-1 - 70 hp (52 kW) license-built model from Aeroflyte.[6]

Aircraft on display

  • US Southwest Soaring Museum[7]
  • New England Air Museum[8]
  • North Carolina Museum of History[9]
  • South Yorkshire Aircraft Museum, Doncaster[10]

Specifications (Typical B-8M, standard rotor)

Bensen B-8M Gyrocopter at the Canada Aviation Museum

Data from Jane's All The World's Aircraft 1982–83[11]

General characteristics

  • Crew: 1
  • Length: 11 ft 4 in (3.45 m)
  • Height: 6 ft 3 in (1.91 m)
  • Empty weight: 247 lb (112 kg)
  • Max takeoff weight: 500 lb (227 kg)
  • Fuel capacity: 6 US gal (5.0 imp gal; 22.7 l) or 9.7 US gal (8.1 imp gal; 36.7 l) in a combined seat/fuel tank, with provision for an auxiliary tank for ferrying
  • Powerplant: 1 × McCulloch Model 4318AX 4-cylinder air-cooled 2-stroke horizontally-opposed piston engine, 72 hp (54 kW)
  • Main rotor diameter: 20 ft 0 in (6.10 m)
  • Main rotor area: 314.2 sq ft (29.19 m2)
  • Blade section: Bensen G2
  • Propellers: 2-bladed Aero Prop Model BA 48-A2fixed-pitch pusher propeller, 4 ft 0 in (1.22 m) diameter

Performance

  • Maximum speed: 85 mph (137 km/h, 74 kn)
  • Cruise speed: 60 mph (97 km/h, 52 kn) maximum
45 mph (39 kn; 72 km/h) economical
  • Minimum speed: 15 mph (13 kn; 24 km/h)
  • Take-off speed: 20 mph (17 kn; 32 km/h)
  • Landing speed: 7 mph (6 kn; 11 km/h)
  • Range: 100 mi (160 km, 87 nmi)
  • Ferry range: 300 mi (480 km, 260 nmi) with auxiliary fuel tank
  • Endurance: 1 hour 30 minutes
  • Service ceiling: 12,500 ft (3,800 m)
  • Rate of climb: 1,000 ft/min (5.1 m/s)
  • Take-off run: 300 ft (91 m)
  • Landing run: 0 ft (0 m) in 9 kn (10.4 mph; 16.7 km/h) wind
  • Landing run: 20 ft (6 m) in nil wind

See also

Aircraft of comparable role, configuration and era

Related lists

References

Notes

  1. ↑ "Bensen B8 Gyrocopter". Canadian Museum of Flight. https://canadianflight.org/content/bensen-b8-gyrocopter. 
  2. ↑ Jenkins et al. AMERICAN X-VEHICLES, X-25 NASA, June 2003. Accessed: 18 February 2012.
  3. ↑ Air Progress: 8. October 1977. 
  4. ↑ Air Trails: 80. Winter 1971. 
  5. ↑ Air Progress Sport Aircraft: 4. Winter 1969. 
  6. ↑ "EAA Fly-In". Flying Magazine: 37. November 1960. 
  7. ↑ US Southwest Soaring Museum (2010). "Sailplanes, Hang Gliders & Motor Gliders". http://swsoaringmuseum.org/collection.htm. 
  8. ↑ Bensen B-8M 'Autogyro'"
  9. ↑ Lewis, Rebecca, (2003) Flight of the Imagination, North Carolina Museum of History, Office of Archives and History, N.C. Department of Cultural Resources, retrieved 4 September 2013
  10. ↑ https://www.southyorkshireaircraftmuseum.org.uk/our-aircraft
  11. ↑ Taylor, John W.R., ed (1983). Jane's All the World's Aircraft 1982-83 (73rd ed.). London: Jane's Publishing Company. pp. 528–530. ISBN 978-0-7106-0748-5. 

Further reading

  • Simpson, R. W. (1998). Airlife's Helicopters and Rotorcraft. Ramsbury: Airlife Publishing. pp. 209–10. 
  • Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. pp. 152–53. 
  • World Aircraft Information Files. London: Bright Star Publishing. pp. File 890 Sheets 25–26. 

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

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