Gettin her going....

Discussion on Stirling or "hot air" engines (all types)
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Mountain Stirling
Posts: 9
Joined: Sat Nov 10, 2007 6:48 pm

Gettin her going....

Post by Mountain Stirling »

Hey guys, great site and wonderful forum. I have a few questions and maybe some of you guys can help me out. I built a stirling walking beam and am having "partial success". :-? It runs when thre is a LOT of heat applied to it, and then only briefly and slowly. I am thinking that the models I see running do not require huge amounts of heat (I am using a sterno cup AND a propane torch). I have experimented with diffirent piston materials (JB weld, Bronze-way to heavy, chrome vanadium-just did not work/weight), I have adjusted the timing, and tightened up all loose ends (but not too tight), displacer turns freely 2-3 times when connected to flywheel and power piston disconeccted, I am using a sawblade for flywheel (is this too heavy) or do you guys think that timing is an issue. I am seeing "steam" coming out of the displacer top (which in spite of advice I have sealed with 30 wt oil drops) and at the piston which I lube with 3-1 oil ( and 30 wt.) it seems that it will only work with the heavier oil. Any ideas or suggestions would really be appreciated. Also, how much pressure and vacuum do these things generate at the power piston??? I ask becasue I am wondering if there is a problem in my displacer cylinder.
alpha stirling
Posts: 35
Joined: Sun Apr 29, 2007 9:24 am

Post by alpha stirling »

the tin can stirlings are very low-power, demonstrational engines only. This means that any friction slowing the mechanics down might cause it to stop. In your case I suspect the thick oil you are using. Other reasons might be timing, leaks and other than piston related mechanical issues...
They told me one cannot build a jet engine in garage conditions. I proved them wrong and I was only 16 :P

Don't let people's sayings discourage your creativity!
speedless
Posts: 36
Joined: Fri Apr 06, 2007 1:58 pm

Re: Gettin her going....

Post by speedless »

Hi
First check the displacer cylinder for leaks,IF theres steam coming out there must be water coming in.Blow and suck all you can in the free end of the power-cylinder and listen for leaks in the displacer cylinder.
Water in the displacer cylinder will turn into steam and then condensate in the power cylinder,this will in turn block the piston.
Anotherway to check the displacer action;remove power-piston,place a ballon on the the free end of the power-cylinder,heat up and turn the flyweel.
About moulded pistons,Please take a look at "hi there" in this forum.
My 2 versions turns 1-2 times WITH the piston connected!
Good luck
Jan
Mountain Stirling
Posts: 9
Joined: Sat Nov 10, 2007 6:48 pm

Post by Mountain Stirling »

Thanks guys for the direction. I have never seen one of these operate outside of the internet, and I just needed an idea of how loose to make the moving parts. If these are supposed to spin freely with the power piston connected then obviously mine is way too tight. I will follow your suggestions.
speedless
Posts: 36
Joined: Fri Apr 06, 2007 1:58 pm

Post by speedless »

Hi
I wasnt to clear in my last post.Sorry
The engine wont run freely with the piston connected,you should be able to feel and hear the compression/sucktion when turning the engine.
Whitout the piston connected mine will spinn more than 10 times.
1:The diplacer-piston and flywheel must be in balance before the piston
is connected.
Tip:First balance displacer-piston to the beam alone,then connect flywheel and balance the hole thing again with a piece of tape and a coin on the flywheel.
2:The displacer-piston rod MUST move very freely and noiceless.
3:The piston must move freely and be tight enough to make a noticeable compression,try this with your hand.It should bounce back when pushed forward and reverse.
Hope any of this will help.:)
When (not if) you get the engine working,you will understand the importence of listening,these things are alive,theres the "hearthbeat" and the "breathing" and sometimes very sensetive,a bit like steam engines.
Sorry for the english.
Jan
Mountain Stirling
Posts: 9
Joined: Sat Nov 10, 2007 6:48 pm

Post by Mountain Stirling »

Jan, thanks for clearing that up. I think I was leaning more toward expecting the the force of the power piston to overcome the inbalance in the wheel. So my new approach and "mantra" will be balance. I have added a bearing to the walkiing beam to cut down on friction. It does seem like when I get it fired up the power piston does not want to fully compress and vacuum the entire length of the piston tube, this seem to result in the power piston hitting the compression stroke at the 11:00 position rather than the 9 or 8 o'clock position (could this be timing?)Sorry to draw you into such mess, thanks for everything.
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