The engine is based around a single piston and runs on compressed air. The reduced parts count is a result of using the propeller axle as a key component in the engine itself. There are flat ...

For example, [Tom Stanton] took a previous air engine design, did away with the air compressor ... what can be achieved with 3D printed parts these days. We love seeing the iteration evident ...

The Ranger Air 330MPX engine drive delivers five functions into one unit: air compressor, generator, battery jump assist, battery charge, and multi-process welder.