Motocycle Manufacturing Company as the Alfaro. It was a perfect example of the "put in everything" design, as it included a sleeve valve system based on a rotating cylinder head, a design that never entered production on any engine. It was later developed further for use in the Doman helicopter by Stephen duPont, son of the president of the Indian Motorcycle Company, who had been one of Alfaro's students at Massachusetts Institute of Technology. Bristol The Bristol Axial Engine of the mid-1930s was designed by Charles Benjamin Redrup for the Bristol Tramways and Carriage Company; it was a 7-litre, 9-cylinder, wobble-plate type engine. It was originally conceived as a power unit for buses, possibly because its compact format would allow it to be installed beneath the vehicle's floor. The engine had a single rotary valve to control induction and exhaust. Several variants were used in Bristol buses during the late 1930s, the engine going through several versions from RR1 to RR4, which had a power output of 145 hp at 2900 rpm. Development was halted in 1936 following a change of management at the Bristol company. Wooler Perhaps the most refined of the designs was the British Wooler wobble-plate engine of 1947. This 6-cylinder engine was designed by John Wooler, better known as a motorcycle engine designer, for aircraft use. It was similar to the Bristol axial engine but had two wobble-plates, driven by 12 opposed pistons in 6 cylinders. The engine is often incorrectly referred to as a swashplate engine. A single example is preserved in the Aeroplane Gallery of the Science Museum, London. H.L.F. Trebert Some small barrel engines were produced by the H.L.F. Trebert Engine Works of Rochester, New York for marine usage. Present day Dyna-Cam The Dyna-Cam engine originally came from a design by the Blazer brothers, two American engineers in the brass era automotive industry who worked for Studebaker in 1916. They sold the rights to Karl Herrmann, Studebaker's head of engineering, who developed the concept over many years, eventually taking out US patent 2237989 in 1941. It has 6 double-ended pistons working in 6 cylinders, and its 12 combustion chambers are fired every revolution of the drive shaft. The pistons drive a sine-shaped cam, as opposed to a swashplate or wobble-plate, hence its name. In 1961, at the age of 80, Herrmann sold the rights to one of his employees, Edward Palmer, who set