The Markel Radial Engine|
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The Antonio Sanchez hybrid engine
A brilliant engine design by a NASA Engineer , Antonio Sanchez , using new materials and designs , the site has an animation and detailed information on the performance of the engine and is available in both English and Spanish versions. (This design does show that the rack and pinion system designed by the author for the raising and lowering of pistons in the Rotary Pulse Jet Engine will work.) A well designed site with numerous links for would be inventors. There are excellent animations and photographs of the Antonio Sanchez Hybrid Engine.
Here is an article from the pages of Popular Mechanics , on a daring design for a Rotary piston engine , originating in Spain.