Dynasphere (vehicle)
The Dynasphere is a monowheel vehicle design patented in 1930 by John Archibald Purves FRSE from Taunton, Somerset, UK.
Purves' idea for the vehicle was inspired by a sketch made by Leonardo da Vinci.
Design
Two prototypes were initially built: a smaller electrical model, and one with a gasoline motor that attained either 2.5 or 6 horsepower depending on the source consulted, using a two-cylinder air-cooled Douglas engine with a three speed gear box, also providing reverse. The Dynasphere model reached top speeds of. The gasoline-powered prototype was high and built of iron latticework that weighed. The next generation version had ten outer hoops, covered with a leather lining, shaped to present a small profile to the ground.The driver's seat and the motor were part of one unit, mounted with wheels upon the interior rails of the outer hoop. The singular driving seat and motor unit, when powered forward, would thus try to "climb" up the spherical rails, which would cause the lattice cage to roll forward. Steering of the prototype was crude, requiring the driver to lean in the direction sought to travel, though Purves envisioned future models equipped with gears that would shift the inner housing without leaning, thus tipping the Dynasphere in the direction of travel. The later ten-hoop model had a steering wheel engaging such tipping gears, and was captured in a 1932 Pathé newsreel, in which the vehicle's advantages are first described and then demonstrated at the Brooklands motor racing circuit. Beatrice Shilling and the inventor's son C E Purves subjected the model to a road test, which included an attempt to pull it over. A novelty model was later constructed by Purves that could seat eight passengers, the "Dynasphere 8", made specifically for beach use.