M35 - Rupp hot air engine

Technical details
Year of acquisition 2007
Power piston stroke 9,3 mm
  diameter 17,8 mm
Flywheel  diameter 32 mm
  material aluminum
Idle speed unmeasured
Energy source alcohol
Mass 225 g


Some motors are difficult to build with just the technology available to a hobbyist. I therefore decided to acquire a completely assembled model of the Rupp engine (an open cycle hot air engine) from Hermann Schmidt
The initial reply was: "It's no longer in stock". After a while I received an e-mail notifying me that the Rupp engine was once again available. I was thrilled! 

The engine keeps running happily. I just love that deep plopping sound of the warm air being periodically released...