Damau
Junior Member
- Joined
- Apr 27, 2012
- Messages
- 18
- Reaction score
- 8
http://s1245.photobucket.com/albums/gg593/DaleMauney/Model Engines/?action=view¤t=Stirling.jpg
I completed this engine in 2007 and never could get it to run like it is supposed to. It would run about 5 or 6 revolutions and stop and even that required a lot of heat from a propane torch. I finally got tired of messing with it and gave up on it and decided it would probably never run.
Recently I read a couple of threads on this forum where members were having problems getting theirs to run. They took the advice of several members' suggestions were successful in making improvements and finally getting theirs' to run.
Now that I was armed with some suggestions from the threads I had read, my interest perked and I went to work on mine. I checked to see if I had any air leaks and sure enough, I did have a minor leak that needed to be sealed.
I disassembled the displacer, made new gaskets, and reassembled using RTV silicon sealant. I also checked the timing of the displacer and the power piston and found that to be a degree or two off the necessary 90 degrees.
These little tweeks proved to be worthwhile and the little engine would now run. This being my first engine build, I almost wet my pants with all the excitement of seeing it live.
It still was not right and I knew it was requiring too much heat. Heat would be conducted throughout the engine, even the flywheel would get hot.
I continued tweeking and trying to reduce friction and it seemed to get better each time. I was on the late, Jerry E. Howell's website and found a tip that improved my little engine more than anything I have tried. Thanks to Jerry's family for keeping his site online.
The tip I am referring to is, making a "waist" area between the hot cap and the cold end of the displacer. THIS REALLY WORKS!!!!!!
Here is a link to Jerry's website where he talks about heat conductivity: Pay close attention to the 3rd. and 4th. paragraphs. That is where he talks about heat conductivity.
http://www.model-engine-plans.com/engineeringtips/heatabsorbers.htm
After reading that, I decided to turn a "waist", not waste, on the hot cap of my engine. Per Rudy Kouhoupt, my hot cap is made of copper tubing. I knew turning soft copper would be a challenge and it was. I made cuts of .001 to .002 with a very slow feed rate until I got the displacer wall about as thin as I felt comfortable with.
I stopped turning the "waist" when the displacer walls were about .020 thick. I thought that would be thin enough for soft copper.
Below is a picture of my hot cap after I turned the "waist":
http://s1245.photobucket.com/albums/gg593/DaleMauney/Model Engines/?action=view¤t=IMAG0210.jpg
Jerry Howell was right!!! The less metal, the less heat it will conduct. Even though I did not go as thin as Jerry said he had done, it did make a big improvement on my little Stirling.
Here is a video of it running on a propane flame after about 15 seconds of warm up:
http://s1245.photobucket.com/albums...ine Videos/?action=view¤t=VIDEO0028.mp4
Stirling engines must be like wine, they get better with age. Here is a short video of it running from the heat of a little alcohol burner I made from some scrap 6061. The fuel is denatured alcohol.
http://s1245.photobucket.com/albums...ine Videos/?action=view¤t=VIDEO0029.mp4
I hope that my efforts with this post will help someone else. Thanks go to the members that posted suggestions in the previous threads about this engine and to the late, Jerry E. Howell.
Your comments are welcomed.
I completed this engine in 2007 and never could get it to run like it is supposed to. It would run about 5 or 6 revolutions and stop and even that required a lot of heat from a propane torch. I finally got tired of messing with it and gave up on it and decided it would probably never run.
Recently I read a couple of threads on this forum where members were having problems getting theirs to run. They took the advice of several members' suggestions were successful in making improvements and finally getting theirs' to run.
Now that I was armed with some suggestions from the threads I had read, my interest perked and I went to work on mine. I checked to see if I had any air leaks and sure enough, I did have a minor leak that needed to be sealed.
I disassembled the displacer, made new gaskets, and reassembled using RTV silicon sealant. I also checked the timing of the displacer and the power piston and found that to be a degree or two off the necessary 90 degrees.
These little tweeks proved to be worthwhile and the little engine would now run. This being my first engine build, I almost wet my pants with all the excitement of seeing it live.
It still was not right and I knew it was requiring too much heat. Heat would be conducted throughout the engine, even the flywheel would get hot.
I continued tweeking and trying to reduce friction and it seemed to get better each time. I was on the late, Jerry E. Howell's website and found a tip that improved my little engine more than anything I have tried. Thanks to Jerry's family for keeping his site online.
The tip I am referring to is, making a "waist" area between the hot cap and the cold end of the displacer. THIS REALLY WORKS!!!!!!
Here is a link to Jerry's website where he talks about heat conductivity: Pay close attention to the 3rd. and 4th. paragraphs. That is where he talks about heat conductivity.
http://www.model-engine-plans.com/engineeringtips/heatabsorbers.htm
After reading that, I decided to turn a "waist", not waste, on the hot cap of my engine. Per Rudy Kouhoupt, my hot cap is made of copper tubing. I knew turning soft copper would be a challenge and it was. I made cuts of .001 to .002 with a very slow feed rate until I got the displacer wall about as thin as I felt comfortable with.
I stopped turning the "waist" when the displacer walls were about .020 thick. I thought that would be thin enough for soft copper.
Below is a picture of my hot cap after I turned the "waist":
http://s1245.photobucket.com/albums/gg593/DaleMauney/Model Engines/?action=view¤t=IMAG0210.jpg
Jerry Howell was right!!! The less metal, the less heat it will conduct. Even though I did not go as thin as Jerry said he had done, it did make a big improvement on my little Stirling.
Here is a video of it running on a propane flame after about 15 seconds of warm up:
http://s1245.photobucket.com/albums...ine Videos/?action=view¤t=VIDEO0028.mp4
Stirling engines must be like wine, they get better with age. Here is a short video of it running from the heat of a little alcohol burner I made from some scrap 6061. The fuel is denatured alcohol.
http://s1245.photobucket.com/albums...ine Videos/?action=view¤t=VIDEO0029.mp4
I hope that my efforts with this post will help someone else. Thanks go to the members that posted suggestions in the previous threads about this engine and to the late, Jerry E. Howell.
Your comments are welcomed.