Need help with our gamma school project engine

Discussion on Stirling or "hot air" engines (all types)
hayman
Posts: 12
Joined: Thu Jul 28, 2011 1:13 pm

Re: Need help with our gamma school project engine

Post by hayman »

We just have one of those laser point temp guns at work.

We are having off and on success with a alcohol flame. We can get it to run everytime with a mapp gas torch...

Do you thing the heating section on our displacer is too short. As in the cooling fins are 2" long and the heating is only 1"?

Also what are you burning for alcohol? We are using 99% isopropyl.
Ian S C
Posts: 2218
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Need help with our gamma school project engine

Post by Ian S C »

hayman, I use methylated spirits for the spirit burners that I use, the only thing different about them is that I use a bundle of 26swg iron wire for the wick, got the idea from the "Model Engineer" vol 1 (1898), once you could use asbestos string, its a bit hard to get these days!
was looking at the pic of your motor yesterday, and thought that I might have left off the last 3 or 4 fins at the hot end, but no matter. If I was building from new I would make the cold end about half, or a bit less of the total length of the cylinder, unless I was making it as I do out of mild steel tube with either aluminium fins pressed on and covering the cold 1/3, or a water jacket, usually soldered on. There are more photos in my album on the model engineering web site. But as the motor works, don't get carried away, build an improved one. Ian S C
PS, a worthwhile experiment. You need an electric motor (perhaps an eletric drill), in your casefit a rubber tyered wheel in the chuck and run it against the flywheel, rotate the motor in its normal direction, you might need 10 15 miniutes running, but if your motor is any good there will be a noticabledrop in temperature at the hot end, and rise of temperature at the cold end. A good science lab demo. The best I'v got is minus 22 deg C.
Post Reply