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Hi,

I have a question about gamma engine. In most description of gamma engine is not clearly marked rule of displacer piston. I analyzed how works this engine and I conclusions:

1. Displacer piston it's not normal piston. This is specific element which mixed a air. Displacer pistion can not be very tight (like a true piston).
2. Power pistion is pistion which produces a force and displacer pistion is the specific timing.

It is true?


Regards

I am new to the Stirling world myself but I think yes to both 1 & 2.

However "displacer pistion is the specific timing" might be worded differently. Timing is more of a correlation of both the displacer and power piston. Displacer being 90 degrees advanced of the power piston appears to be the standard.

Hawke wrote:I am new to the Stirling world myself but I think yes to both 1 & 2.

However "displacer pistion is the specific timing" might be worded differently. Timing is more of a correlation of both the displacer and power piston. Displacer being 90 degrees advanced of the power piston appears to be the standard.

I am also a beginner. At first I thought power piston pushing by pressure. Now I know it is not. Pressure pushing power piston!

[tab=20]A good basic video explaining the cycle but also ...has some things that we have to address when building them. They are picky about friction vs air leaks.
http://www.youtube.com/watch?v=H1IkVMSBMRg

[tab=20]The better the temp difference the more potential power you get but it must be utilized wisely. My first engine is losing speed which I am thinking Im getting some air leaks. Each build gains experience of how to optimize the mechanics.

Hawke,
Everything you said sounds right to me. The displacer is just that. It displaces or moves the hot air up and the cold air down, Thats why you dont want it to fit tight in the cylinder.The displacer can also serve as a regenerator . Thats why some people make the displacer out of wrapped steel wool. The air can move through it and it helps to preheat and precool the air.

with a small unpressurised engine, you don't need to get too fancy with regeneration, a plain light weight cylindrical displacer will serve enough as a regenerator, and is simple. The thing is to get the ratios between the displaced volume of the power piston, and the displacer about right. For a high temperature motor (not a tin can one), the ratio is 1.5 : 1, the displacer being the larger volume. The displacer its self should be about three times its diameter long, and have a gap between it and the cylinder, a 1/16", or 1.5 mm is not a bad figure for this, and a similar size gap top and bottom. The displacer must not touch the sides, or ends. Ian S C