Technical details
Year of construction 1998
Power piston stroke 14 mm
  diameter 20 mm
Displacer piston stroke 15 mm
  diameter 20 mm
Flywheel  diameter 2 x 29,5 mm
  material aluminum / lead
Idle speed 830 rpm
Energy source alcohol
Mass 850g 


While searching the web for hot air engines, I quickly bumped into Roy Rice's and Richard Egge's interesting "little engine pages". Finding a detailed description of an engine with a rhombic gear on these pages, I felt compelled to build one. The tiny parts required real laborious detail work. Exept for the gears, all parts were sawed, filed and ground by hand, achieving a level of precision sufficient for the gear assembly to function. The gear wheels are standard manufactured parts; I commissioned a mechanical workshop to build the cyclinder and piston. 
The displacer cylinder is made of a DURAN test tube with an inside diameter of 24 mm; an aluminum cigar-tube serves as displacer piston. 
Aiming for a true and smooth running engine, I balanced the flywheels by filling drill holes in the flywheels with lead as necessary.