"Cycling in the air": Alex Moulton and Human-Powered Flight

on Monday, 27 September 2021. Posted in Archives, Wiltshire People

The 1950s were wonderful years for science and engineering, where anything was possible. Sputnik 1 was launched into space, the first passenger jets entered service, and people apparently flew around on their own personal helicopters:

Man stood on platform hovering a few feet above the ground, with blades rotating beneath him.

The heli-vector stood on the ground with two sets of rotator blades resting on four padded feet..
The “Heli-Vector”, a type of personal helicopter with two sets of rotors mounted underneath the platform. ©The Aeroplane, 8 April 1955.

Alex Moulton was also very busy in these years. He might be best known for his work on the Mini (the suspension he designed for the Mini owed its roots to his work on ‘Flexitor’ suspension for the Austin Gipsy in the 1950s), but he was a prolific inventor who was interested in almost all areas of engineering design, from steam-powered cars to wheelchair suspension.

Moulton enjoyed novel or interesting engineering challenges, and the “Heli-Vector” personal helicopter above certainly caught his eye as he made a cutting of the article and filed it away for future reference. But Alex Moulton was as much a sportsman who enjoyed physical challenges as he was an engineer, and so when he read an article in a 1955 edition of The Aeroplane which talked of a pre-war German experiment with human-powered flight, the seeds of an idea took root.

Man in recumbent bicycle incorporated into a plane cockpit with wing and propeller above.
Cockpit of early prototype human-powered aircraft. ©B. S. Shenstone, ‘The problem of the very low-weight, highly-efficient aeroplane’, reprinted from the Canadian Aeronautical Journal, 2:3 (1956)

Moulton’s personal papers contain a small file of material on human-powered flight. The material mainly consists of correspondence with scientists and engineers working in the field, and Moulton’s letters show his passionate enthusiasm for the concept. In fact, he joined the Low Speed Aerodynamics Research Association in 1956, and wrote to its Director of Research to say “I would like to support, in any way possible, activity in the direction of studying and achieving Man Power Flight”. The papers also include numerous studies and reports which aimed to prove that, theoretically at least, human-powered flight was possible.

A 1955 article in The Aeroplane set out the calculations: “a pre-war German design, the Haessler-Villinger, had an empty weight of 77lb and required only 0.82 bhp to fly at 30mph” whereas a new, more lightweight and aerodynamic, design could be flown at 30mph using only 0.68 horsepower. It was theorized that two people could produce just under 1 horsepower if power was generated by the pilot using their legs only (presumably their arms were being used to fly the plane!) and the co-pilot using both their legs and their arms. If you think that generating power using your legs sounds suspiciously like a bicycle, then you’d be right:

Diagrams and plans of plane in profile and from above powered by tandem bicycle mechanism.
Proposed design of a human-powered aircraft. © London Illustrated News 1955

Early ideas for human-powered aircraft seem to have been based around creating what was effectively a tandem bike inside the cockpit, with the addition of a linked handcycle arrangement for the (presumably very fit) co-pilot. Perhaps it was the centrality of the bicycle that attracted Moulton’s interest. He began corresponding with several people involved in the Royal Aircraft Establishment’s Man Powered Aircraft Committee (MAPAC), principally a member of MAPAC called David Rendel. MAPAC considered two main designs for the aircraft: a fixed wing design, and an ornithopter (an aircraft with flapping wings, similar to those of a bird). Both were to be pedal-powered.

Man standing on framework supporting a winged flying machine.
Edward Frost’s 1902 ornithopter (Wikimedia Commons)

Rendel favoured the flapping wing design, whereas MAPAC were more taken with the idea of a fixed-wing mounted to a tandem, an idea first suggested by Dr Wilkie, a researcher at UCL’s Department of Physiology. Wilkie suggested that an experimental plane should be built “driven by wheels only”, and that the first attempt at flight should be limited: “the machine is to be accelerated along the ground to above its take-off speed, being held in contact by using the control surfaces, then, when maximum speed has been reached, flown off the ground for as long a gliding hop as possible”. If this couldn’t be achieved, Wilkie added somewhat presciently, “man-powered flight with a fixed-wing aircraft of this general type is impossible”.

Like any good engineer, Moulton wanted to test both hypotheses. He wrote to Rendel in January 1958, saying “I confirm that I believe Dr Wilkie’s suggestion for the experiment of a tandem fitted with a wing, to be an admirable one, as it would be essentially a simple machine to make and the basic structure of the tandem itself is a very efficient one, with the strength in the right plane for the addition of the wings”. He even offered practical support if MAPAC had difficulty sourcing parts from larger bicycle manufacturers: “I would be prepared to make myself responsible for the supply of and adaption of the cycle part of this project”. He also wrote directly to Wilkie to say “I am very much in favour of this approach due to the relative ease with which the experiment can be made. I have offered through MAPAC to help this proposal”.

Cockpit with seat, pedals and chain for human powered airplane prototype.
Cockpit of a second early design of human-powered aircraft. © Shenstone, ‘The problem of the very low-weight, highly-efficient aeroplane’.

Moulton also told Rendel that “regarding your ornithopter proposal, I have read your report, and believe that this is, in the end, the most interesting and significant of the project proposed”, because of “the potential combination of the low take-off speed and manoeuvrability together with the simplicity and portability of the apparatus”. “I think therefore,” he added, “that when ultimately developed, it could be a sporting device of some considerable significance”.

MAPAC eventually decided to focus only on the fixed-wing design, and Moulton wrote to a downhearted Rendel “certainly, the minutes of the proceedings of your 6th meeting make sad reading, but I do not think one should ever take much notice of such a negative outlook. On the contrary, quite regardless of what course the main Committee is bent upon taking, I believe we should cling to the two constructive ideas, namely…the tandem project…and secondly your experiments on the elements of an ornithopter”.

Moulton offered more practical help to Rendel (“I am sure that I can help you to get the rubberised components made, directly you run into any difficulties with your own facilities”), but he also began experiments of his own. He designed and built a dynamometer to measure the power generated by kayakers to see what sort of force could be produced by human arms. This information would be critical to the success of the experiment, as without sufficient power from the co-pilot’s arms the plane would not generate enough power to fly. Moulton also wrote to Wilkie to ask if he had considered “the instantaneous performance of man such as in making one stroke with a significant recovery period afterwards” and suggested that he perform experiments to measure “the momentary power output of a weight-lifter”.

Letter offering help with the design or manufacture of the power trade mechanism or rubber energy storage device for a human-powered flying machine.
Alex Moulton to David Rendel, 21 May 1959 ©Alex Moulton Charitable Trust

There is then a break in the correspondence, possibly due to Moulton being occupied with other projects and waning enthusiasm for the idea within MAPAC. The final exchange between Moulton and Rendel came in May 1959, when MAPAC was transformed into a group of the Royal Aeronautical Society. Moulton wrote “if in any practical project I can be of assistance in the design or manufacture of:- (a) The power trade mechanism. (b) A Rubber energy storage device, I shall be very glad to help”.

The idea for human-powered flight, or Alex Moulton’s active interest in it, seems to have begun to peter out by the early 1960s. Moulton was still curious, at least in passing, about the idea in the mid-1960s but was no longer offering to provide practical help; by the 1970s his interest seems to have lapsed entirely.

“Flying by the sweat of one’s brow as opposed to the seat of one’s trousers is not exactly a new idea; in fact there are various and several recorded instances of attempts at man-powered flight – some merely unsuccessful, others frankly disastrous” (‘Aviating by Muscle Power’, The Aeroplane, 18 November 1955, p. 777).

Tom Plant, Project Archivist: Breaking the Mould: the Spencer Moulton and Dr Alex Moulton archives

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