Stirlingengineforum.com

Hi,

I am new here, my first post, so.... well i make all kind of mistakes and i need your help.
I have successfully built a lamina flow engine and it runs nicely. It is made with airpot graphite piston and cylinder set and i used a hard drive as a flywheel, testube with steel wool at the hot end. So far so good. But after a while i noticed a few problems, that i want to improve.
1. The test tube deforms slightly when heated with alcohol burner. It warps and after it cools down it remains warped. Is it a poor quality of the test tubes that i am using? Would it made any difference if i get a better quality test tubes? (I bought these on eBay and were not cheap, i guess they are borisilicate glass as they don't crack)
2. The rubber gasket that holds the test tube gets very hot and starts to smell and i can see some fumes come out of it. (It does seal the engine very good and no problems other than that) but any ideas to improve this are welcome.
3. This is a tough one. I noticed that my engine "prefers" counter clokwise direction over a clokwise direction. Everything seems to be built symetrically and the only thing that comes to my mind is that the bearing in hard drive flywheel must prefer one direction. ( ) Any ideas?
Thanks for your kind help, Boki

Too much heat required. If it's not running after 45 seconds, blow it out. Tweak it. The hole on the piston side of the Airpot should be 3/16"or 5mm.
If it is already too large, choke it down with a washer superglued over the hole. The hot side of the Airpot cylinder should be enlarged up to 1/4" or
6mm and to within 1/8" of the cold side. Your test tubes should be ok. I epoxied the test tube in place (better seal) but still used the washers for side
support on the test tubes. You are absolutely correct on your bearing thoughts. I have confirmed this using several platters and most prefer counter-
clockwise. Remove the plates and spin the bearings in both directions. The drag in the clockwise direction will be small but obvious. It matters. If you find one that has balanced drag, your results will be amazing because this affects the start up as much as the direction. Good luck.

Hi, thanks for reply. I see. The engine runs on a small candle, however it runs way faster on a spirit burner. I burnt a candle and the engine was running for a few hours continously and the test tube remained intact. It seems, that spirit burner is so hot, that it softens the glas of the test tube.... i don't know if my test tubes are a problem or maybe a superior brand like Duran would perform better. Thanks for the tips about the construction, it seems, that i got very close to your measurements, so no problems there. I have drilled a 5.2mm hole in the airpot and i have approx. 21mm piston stroke. I guess it was pure luck, since the materials i had available made me take those values (hard drive flywheel).
I now see, that i have problems regulating how intensive the flame is and how much heat is generated. I will try to reduce the lenght of the wick to reduce the flame and see what happens. Thank you for your help. I will post my results. Bye, boki

American Educational Borosilicate Glass Round Bottom Test Tube, 16mm OD x 150mm Length (Pack of 72)
Sold by: Amazon.com LLC
$25.28

I used these . They cut easily. No chips or cracks. Will take a lot of heat.

One idea of these motors is to see how much power can be got out of the motor with the least amount of heat input. What is the displacer made of?
Ian S C