Dissimilar Cylinder Sizes

[Akya2120]

Hello,

I am working on a beta style Stirling, and I am planning on using a 32mm cold end cylinder and a 35mm hot end cylinder. Is there some correct ratio to modify the length/stroke of the displacer by? I know that typically we do 1.5X(Power Piston Stroke) for the displacer stroke, and 3X(Displacer Dia) for the length, but it would seem to make sense that a wider displacer would want less length.

Thanks!

[Ian S C]

Akya, no stick to the 3:1length/dia ratio, the length of the displacer works as a regenerator, if it's a little shorter it won't hurt. I think if I measured all my motors I'd find the ratio would vary from about 2.5:1 to 3.5:1.
All the wider displacer needs is a shorter stroke, although with yours there may not be much difference, you'll find out when you start to work out the volumes, pi R sq x H
Ian S C

[Akya2120]

Okay so I should just not worry about changing the ratios. I was already planning to essentially make the displacer slide about the two ends and shave a mm or two from the center section and add stainless steel wire cloth to act as a regenerator. I was also going to make holes to force the air through the ends of the displacer (around the edges) to duct air past the wire cloth. Seemed like a good way to add regenerator material without changing the weight of the displacer too much. Thanks for the advice!