Jackrabbit Finished                                                                             

Finished engine.

While the house windows are on order, I completed the building of the Jackrabbit engine. The pistons and vessels are completely air tight. 

Air cooler.

The water cooling coil in the second engine worked so well (25ºC maintained) , I put an air cooler in the first engine also. 

Controller and relays.

I mounted the Arduino  micro-controller and the relay boards in a box. I have a well working Arduino program that runs the engine. 

Pressure in vessel A (black), pressure
in B (blue), RPM (red), relays(magenta)

A host computer graphical interface allows me to tweak the engine timing in real time and record engine telemetry. The fans move the air from cold to hot spaces in about a second without causing stray electrical interference now. The heaters maintain 85ºC with about 120 watts of power. 

Unfortunately, the engine is still not self sustaining. I tried many timing schemes but the flywheel eventually comes to a stop. The amount of  friction in the system does not seem to be excessive, so I believe the problem lies with the small amount of  torque that the engine produces. Even if I did manage to get this engine to be self sustaining, I don’t think it could generate enough electricity to power the fans.

My original question was, “Can a Stirling engine extract  usable work from a low temperature gradient?” The answer is, probably no. I could not do it with the small gradient of  60ºC ( cool air of 25ºC and warm air of 85ºC). In my mind, this question has been laid to rest and I can now finally move on to where my muse leads me next.