Cranfield, A
A. Cranfield
Contents
History
Andrew D. Cranfield started his aviation career in free-fall parachuting and designing (with his brother) his own hang glider. He was working at Westland Helicopters in September 1980 when the started design of a human-powered helicopter in an attempt to win the $15,000 prize being offered by the American Helicopter Society for the first man-powered helicopter to hover for one minute and to reach a height of three metres. Initial tests were carried out under Westland sponsorship in their flight hangar at Yeovil, Somerset. The machine was tested with just the lower rotor fitted, and was seen to "skip around the floor". From a purely aerodynamic viewpoint it was computed that the AHS competition requirements were achievable but in practice a number of dynamics problems were encountered particularly in the transmission area. Strengthening modifications followed, including the adoption of an aluminium alloy crank/spigot assembly, as well as an increasing of the hub separation and the blade root cut out. Despite these changes power output still remained limited, and stability and control problems were also apparent, possibly due in part to wake, re-circulation in the confined hangar space.
Subsequently Vertigo was transferred to the old airship hangars at Cardington, Bedfordshire, but time and money precluded continuing development and the project was abandoned in 1988. Vertigo was presented to The Helicopter Museum in April 1989, by which time much damage had been done to the fragile structure, in particular the rotor blades. Nevertheless sufficient of this interesting project has been salvaged to demonstrate the level of technology achieved.
After being awarded a Fellowship at Cranfield University, Andrew left Westland Helicopters and his subsequent management career has included working at Optica Aircraft, Lucas Aerospace and running P&M Aviation. He has held senior management positions in other, more profitable, high technology businesses. He currently works as a Non-Executive Director and, amongst other activities, is involved in supporting the Waterbird project (a replica of the UK’s first-ever seaplane) and contributing to an initiative to enhance the skills of UK flexwing microlight pilot.
Company References
- Interview with the man who built a human-powered helicopter (and worked with the legendary Edgley Optica), Hushkit 8 March 8 2022, available via the Wayback Machine
- Cranfield Vertigo at The Helicopter Museum, available via the Wayback Machine
Project Data
| Project No | Type No | Name | Alternative Name(s) | Year | Spec (Requirement) | Status | Qty | Description | References |
|---|---|---|---|---|---|---|---|---|---|
| Vertigo | 1980 | Pro(n) | 1 | !S human powered helicopter | 1, 2, 3, 4 |
Project References
- Pedalling towards a vertical take-off, Cranfield, A. D. (Chartered Mechanical Engineer, September 1987)
- http://www.humanpoweredhelicopters.org/vertigo/index.htm, available via the Wayback Machine
- Interview with the man who built a human-powered helicopter (and worked with the legendary Edgley Optica), Hushkit 8 March 8 2022, available via the Wayback Machine
- Cranfield Vertigo at The Helicopter Museum, available via the Wayback Machine
Production Details and Type Description
Human powered helicopter helicopter. Construction of the helicopter was based on a central pilot's support structure using a carbon fibre bicycle type frame with a standard pedal crank/sprocket assembly and a quadropod undercarriage, married to two, two-bladed co-axial rotor (two pairs contra-rotating), each having a diameter of 79 ft and blades with a constant 5 ft chord. The lower rotor was set at 6° dihedral, and the higher rotor at 9° dihedral. In order to take advantage offered by ground effect, the rotors were set as low to the ground, and as closely together, as could be practically achieved, with the fuselage and pilot being located above the rotor assembly. Rotor spar construction was of carbon fibre/honeycomb sandwich caps bonded to styrofoam sidewalls, with styrofoam ribs and skin of heat shrink Mylar. The transmission comprised carbon fibre drive shafts driven by steel bevel gears powered by a chain driven pinion gear. Pitch and coning were built into the alloy hubs. Flight control was intended to be achieved by weight shift, with the pilot moving about to enable this. Power was transmitted by to the rotors by a set of bicycle pedals powering a set of bevel and pinion gears.
Total A. Cranfield Production1