The International Cessna^® 170 Association

From another post.....

Bruce Fenstermacher wrote: my beer can Stirling engine build.

Did you get the Stirling engine built?

My Dad had quite the interest in Stirling engines. I have a small working model that he kept on his bookshelf. It is fueled with a teaspoon of alcohol. One time he mounted a Fresnal lens so as to concentrate the sun's rays and ran it off of solar power. You may have guessed that he was a tinkerer....

I'll have to get it out and take some pictures one of these days. Heck, maybe I'll fire it up.

Yes. Well out of the 5 I built I have one running example. I never could figure out the relationships reguired and they seem to be somewhat critical though with all the thrown together examples found on YouTube you would think not. I have no idea why this one runs and the others don't. This was one of the first runs. After showing it of for a week to everyone I know I kind of refined it by balancing the flywheel and learning exactly what size candle and flame works best,

[youtube]http://www.youtube.com/watch?v=FKs2l9ox9_4[/youtube]

Does anybody remember those glass toys from the 1960s that look like a light bulb with a small rotor inside
spinning on a pin? One side of the rotor blades is white, the other side is black. Any time a strong light shines on the rotor, it would spin. I got one at the State Fair Of Texas when I was a kid and it still works. I always wondered how it worked.

Wouldn't it be reflective on the white side and absorb on the black side creating a differential?

John

Its a radiometer, not a Sterling engine.

http://www.scientificsonline.com/solar-radiometer.html

n3833v wrote:Wouldn't it be reflective on the white side and absorb on the black side creating a differential?

John

Differintial what? Temp? What makes it spin? There has to be a force of some kind but what is it? Temp differential is not a force. I still don't get it.

I still don't get it after reading this:

http://math.ucr.edu/home/baez/physics/G ... -mill.html

I saw a number of similar "engines" on a trailer operating at the Old Time Tractor & Engine Show in Temple, TX some years ago. Pretty interesting. Is this a possible new source of power for Cessna 170's

170C wrote:I saw a number of similar "engines" on a trailer operating at the Old Time Tractor & Engine Show in Temple, TX some years ago. Pretty interesting. Is this a possible new source of power for Cessna 170's

Probably never work well for Green airplanes but maybe for the kind of slow speed expected of Red examples.

hilltop170 wrote:

n3833v wrote:Wouldn't it be reflective on the white side and absorb on the black side creating a differential?

John

Differintial what? Temp? What makes it spin? There has to be a force of some kind but what is it? Temp differential is not a force. I still don't get it.

conversion of thermal to kinetic energy.

hilltop170 wrote: Differintial what? Temp? What makes it spin? There has to be a force of some kind but what is it? Temp differential is not a force. I still don't get it.

The weather man would disagree.

The different colors absorb/radiate heat energy at different rates. This will cause the small amount of air in front/behind the pads to expand/contract at different rates. (air expands when warmed, contracts when cooled).
Since it's a closed system, the resultant force of the air changing density causes a pressure on the pads, causing them to rotate.

It's exactly the same forces as weather ... at a very very basic level.

I still don't get it after reading this:

While a little oversimplified, this is a fairly good explanation:
http://www.howstuffworks.com/stirling-engine.htm

We have started discussing two different things. Most of the questions how something worked have been about the radiometer Richard mentioned.

I'm not sure anyone has asked how a Stirling engine works yet it is just as interesting and mysterious when you try to make one. I was intrigued for about 2 weeks. Studying and trying to understand what I needed to know to make my models work. After doing about nothing for 2 weeks making and the tweaking my models I only have one that runs. I don't know why the others won't and I don't know why the one that runs does.

But every time I fire it up it is mesmerizing. Everyone just hangs around watching it and wondering. Will it keep turning? How long will it run? Is it getting faster? Is it slowing down. Just how does the dard thing work?

The Stirling model that my Dad had looks similar to the one in this link.

http://www.newegg.com/Product/Product.a ... -_-NA-_-NA

I've done some reading about the Stirling engines too and found out that there is a type A with dual cylinders and a type B with a single cylinder. All it takes is some heat and she starts running. My Dad called it an "external combustion" engine and I've seen that term used in some of the things I've read... but it really doesn't need combustion, just heat. A good magnifying glass and some sunlight will make it go.

Bruce-
I didn't mean to hijack your thread, just mentioned another odd working device that intrigued me as a kid and I still don't fully understand.

Did you make your Sterling engines from plans or was there akit available? They are amazing devices.