Stirling Engine without Displacer Piston

[StirlingEnthusiast]

Hello all,

I was wondering if, to eliminate the possible air leak and maintenance of the Displacer piston, I could simply eliminate it and have a free displacer hooked to the sides of the tube with a string. The power would come from two balloon skins on top of my two cans expanding and contracting.

Is this feasible? Will it work well?

*Sorry if I sound dumb, it's because this is my first time in this field.

Thanks,
Enthusiast

[Ian S C]

You can run a Stirling Engine with a free displacer, but you will have to look up Ringbom hot air motors.
It is possible to do away with the crankshaft completely with the free piston motor, a spring system takes place of the fly wheel, and every thing just bounces up and down.
The hot end of the displacer cylinder can either have fins for air cooling, or as I did, form a water jacket around it and water cool it.
Which ever way, there is still a leakage path to atmosphere via the rod on the displacer.
Ian S C
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[cbstirling2]

Is that engine pictured a ringbom design?

[Ian S C]

Yes it is, this is a famous design, being one of the first of this type of motor to be built and published in Engineering in Miniature in 1982.
This little one was built from parts of my first Stirling Engine.
Ian S C
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[Ian S C]

You can of course do without the displacer all together, and build an engine known by a number of names, such as Thermo Acoustic, Pulse Engine, Laminar Flow, Lag Engine. There are a number of threads on these motors on this site.
Ian S C