Stelzer engine
https://en.wikipedia.org/wiki/Stelzer_engine
Quote from: https://en.wikipedia.org/wiki/Stelzer_engine
The Stelzer engine is a two-stroke opposing-piston design proposed by Frank Stelzer. It uses conjoined pistons in a push-pull arrangement which allows for fewer moving parts and simplified manufacturing. An engine of the same design appeared on the cover of the February 1969 issue of Mechanix Illustrated magazine.
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Note in the graphic that, if there were no spark plugs, and the combustion chamber had a flat head like the piston head, there would be detonation rather than a burn.
Normally detonation in a piston engine is destructive, because the piston has nowhere to move after a detonation, because the crankshaft is turning in a direction 90 degrees different than the direction of the piston movement.
In a Stelzer there is no crankshaft. There is nothing to stop piston movement. The tremendous power of detonation can be put to practical use.
