Hi, new member with an interest in hot air (as opposed to LTD Sterling) engines here. Currently building a simple engine, hope to have some pictures very soon.
It doesn't really have a name (!). It's a model that as far as I know it was first published in the early 1900's but refined in the 1930's. It's essentially a closed Stirling cycle like a simplified Henrici with side-mounted power piston.