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I am building a 90 degree V-2 alpha type Stirling. Both cylinders
are sealed with teflon piston rings.

Hot cylinder is 1-3/4" bore, 1-1/2" stroke
Cool ctlinder is 1-1/2 bore, 1-1/2" stroke.

I can't seem to get the engine to run. It seems to have good
compression when turning by hand.

If I connect the shaft to a power source and drive the engine, one
cylinder gets warm and the other cylinder gets cool. This tells me
I am on the right track, but when I apply heat to the cilinder head
I get nothing. I have tried spinning the engine while applying heat
to no avail.

My thought is that the flywheel is not heavy enough to provide the
necessary inertia to keep it rotating.

Any thoughts on flywheel diameter, rim width, weight, etc.?

My feeling is that an alpha type engine must have a very substantial
flywheel compared to other Stirling types.

Any input appreciated.

Jon james

A heavier, more moment of inertia, flywheel should help.

Have you tried this yet?

Let us know your results. Thanks

Hello Jon,

Alpha Stirlings can have fairly high compression ratios so they need a good size flywheel to carry the compression part of the cycle. I have used flywheels that are several pounds in weight for even smaller engines than yours. You may need about 5 pounds. I hope you have good bearings. With a good flick of the hand it should carry the engine for at least 3 or 4 cycles.

Because it is higher compression, it will also require higher temperature differential. The hot end should be red-hot. Water cooling is almost a requirement.

A good regenerator can be a huge help. Besides reducing the compression ratio you will get more work done with less heat input. You will still need to be very hot, just not a large area.

If you are still having troubles, you may want to try to reconfigure to a gamma (displacer type) design. This will make it possible reduce the compression and temp.

Rick