Axial engine
In effect these spaces serving the same purpose as the cylinders of an axial engine, and the sinuous cam surface acts as the face of the pistons.
This design eliminates the multiple reciprocal pistons, ball joints and swash plate of a conventional 'barrel' engine but crucially depends on effective sealing provided by sliding and rotating surfaces.
A four-stroke, air-cooled unit, it had seven cylinders and a variable compression ratio, altered by changing the wobble-plate angle and hence the length of piston stroke.
Its unique feature was the means of transferring the load from the pistons to the swashplate, achieved using tilting slipper pads sliding on a film of oil.
Another innovation by Michell was his mathematical analysis of the mechanical design, including the mass and motion of the components, so that his engines were in perfect dynamic balance at all speeds.
However, it never entered production, reportedly due to limited funds and the Air Corps' growing emphasis on air-cooled radial engines.
The A-4 had much smaller frontal area than water-cooled engines of comparable power output, and thereby offered better streamlining possibilities.
It was rated at 425 hp (317 kW), and weighed only 749 pounds (340 kg), thus giving a power/weight ratio of better than 1:2, a considerable design achievement at the time.
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.
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.
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.
In 1961, at the age of 80, Herrmann sold the rights to one of his employees, Edward Palmer, who set up the Dyna-Cam Engine Corp. along with son Dennis.
Edward's son Dennis and daughter Pat then helped get the engine installed in a Piper Arrow airplane.
Dyna-Cam opened a research and development facility about 1993 and won many various awards from NASA, the United States Navy, the United States Marine Corps, California Energy Commission, Air Quality Management District,[clarification needed] and Los Angeles Regional Technology Alliance for different variations of the same Dyna-Cam engine.
Axial Vector's new engine, like many of the others on this list, suffers from the "put in everything" problem, including piezoelectric valves and ignition, ceramic cylinder liners with no piston rings, and a variety of other advanced features.
A classical, Spanish built design, parallel pistons working in opposition, sine-wave swashplate, in 2023 with two versions, a car sized, with liquid cooling, as prototype, and an air cooled four cylinder, 125 cc, 22 HP, 4.5 kg unit, aimed at drones and big aeromodels, in pre-production stage.
[21] The Cylindrical Energy Module (CEM) is a sine-wave swashplate engine that can also be used as a standalone pump, powered by an external source.
As the powerplant for the Coupe, the CEM would rotate on an axis, sucking in fuel and providing self lubrication and was capable of running on either petrol or diesel.
[22][23] A United States company Devize Motors is currently developing a new engine utilizing opposed pistons.
