# Rudy Kouhoupt Stirling Engines



## MarioM (Sep 11, 2011)

Hi, I am new to this forum. I am finishing a stirling engine from the book "plan sets from the past". Has anybody built one of these engines.


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## Tin Falcon (Sep 11, 2011)

welcome to the board. have not built one get but have a full size plan set from Rudy. 
several here have done similar engines. 
Tin


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## MarioM (Sep 11, 2011)

Tin Falcon  said:
			
		

> welcome to the board. have not built one get but have a full size plan set from Rudy.
> several here have done similar engines.
> Tin



Than you very much for your reply. My home address is in Ecuador, so English is my second language, sorry if 
I make mistakes.

Actually I just finished the engine, but it does not look alive at all, it fills OK when run it by hand but no kickback.......I think it has leaks.......any ideas??


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## maverick (Sep 11, 2011)

Wecome MarioM,
  I have built 2 compressed air engines from Rudy's plans and find the plans to be
 accurate and easy to follow. Good luck on the Stirling.

 Regards,
 Mike


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## Longboy (Sep 12, 2011)

MarioM  said:
			
		

> ............Actually I just finished the engine, but it does not look alive at all, it fills OK when run it by hand but no kickback.......I think it has leaks.......any ideas??


 Your engine doesn't run because it has air leaks or suffers from friction in the moving parts. The feel by hand doesn't tell you much, the engine sees something it does not like. A good place to start is to remove the power piston and blow some compressed air at low pressure into the cyl. so the leaks present themselves but I don't know what plans you worked from and you may be unable to get a blow-off nozzle over the power cylinder.


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## MarioM (Sep 12, 2011)

Longboy  said:
			
		

> Your engine doesn't run because it has air leaks or suffers from friction in the moving parts. The feel by hand doesn't tell you much, the engine sees something it does not like. A good place to start is to remove the power piston and blow some compressed air at low pressure into the cyl. so the leaks present themselves but I don't know what plans you worked from and you may be unable to get a blow-off nozzle over the power cylinder.


This is the first stirling I made and and was a bit anxious to finish it. I will now try to find where the leaks are and see what happens. Thank you for your advise.


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## MarioM (Sep 12, 2011)

maverick  said:
			
		

> Wecome MarioM,
> I have built 2 compressed air engines from Rudy's plans and find the plans to be
> accurate and easy to follow. Good luck on the Stirling.
> 
> ...



Thank you very much. I will keep trying.


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## MarioM (Sep 27, 2011)

Tin Falcon  said:
			
		

> welcome to the board. have not built one get but have a full size plan set from Rudy.
> several here have done similar engines.
> Tin


Hi Tin, I found the engine I am building in you tube. Do you know of anybody who built this engine??

[ame]http://www.youtube.com/watch?v=mUr6rsNgBU0[/ame]


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## Stan (Sep 28, 2011)

I don't remember what plans I used, but I built a Stirling that looks like the one in the video.

Sealing air leaks was the solution to get it to run. I made the displacer guide/bushing several times before I achieved a close enough fit. The hot air has to move from the displacer cylinder through the doss drilled hole to the power cylinder. Any leakage around the displacer piston rod will keep it from running.

My other problem was I used stainless steel for the hot end and SS has poor heat conduction. The second hot end was made from brass. That is not ideal but it works.

I use an alcohol lamp under the hot end and it takes quite a while to get hot enough to run, but then runs well. If I am in a hurry to show it to someone, I preheat it with a propane torch and then use the alcohol lamp.


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## lazylathe (Sep 28, 2011)

Hi,

I have plans for a similar engine.
It is from the Home Shop Machinist Volume 23 November/December 2005.
I think it is called "Brassy Babe" though not sure...
The article is just called " Building a Horizontal Stirling Engine"
The magazine, volume and months above are correct.
I do know it is a horizontal Stirling engine.

Will have a look when i get home although it looks to be exactly the same as the one in the video.

Andrew


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## MarioM (Sep 28, 2011)

Stan  said:
			
		

> I don't remember what plans I used, but I built a Stirling that looks like the one in the video.
> 
> Sealing air leaks was the solution to get it to run. I made the displacer guide/bushing several times before I achieved a close enough fit. The hot air has to move from the displacer cylinder through the doss drilled hole to the power cylinder. Any leakage around the displacer piston rod will keep it from running.
> 
> ...



Than you very much for the information. I have already made the displacer guide/bushing twice. Second time was better than first.......at least the engine tried to run, but maybe is not enough. I was also worried about other leaks so to be sure sealed them with RTV sealant, does not look very nice and lacks mechanical touch, but I really need to see that engine running.......I will work on the look later.  The times I have tried to run it has been with the torch.....but if I ever get it running well I will prefer to use an alcohol lamp. Do you remember when you built yours how you sealed the displacer piston assembly.


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## MarioM (Sep 28, 2011)

lazylathe  said:
			
		

> Hi,
> 
> I have plans for a similar engine.
> It is from the Home Shop Machinist Volume 23 November/December 2005.
> ...


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## Stan (Sep 29, 2011)

> Do you remember when you built yours how you sealed the displacer piston assembly.



I had some high temperature gasket paper and I cut gaskets for both ends. I made a gasket for the power cylinder also.


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## lazylathe (Sep 29, 2011)

I use the red high temp gasket sealer in the tube.
Just spread a very thin layer on one surface and screw together.
Wipe the excess away with a paper towel.
On mine you can barely see a very thin red line around the joint.

Make sure the parts fit flush together and you should not have a problem.

Andrew


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## Stan (Sep 29, 2011)

Here is a hint for people who use the silicone type of gasket sealer.

Put a thin layer of sealant on to the cleaned surface and then set the object (sealer side down) on a piece of wax paper. Come back the next day and lift the object of the wax paper, trim away any that squeezed out and you have a gasket attached to one side of the joint but the parts will not be glued together permanently.


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## purpleknif (Sep 29, 2011)

Some good information here! This engine looks to be very similar to the one I'm building from a kit from Little Machine Shop. Thanks for the tips.


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## MarioM (Oct 1, 2011)

Thank you very much for all the information. I will keep working and trying. Will let you know what happens.


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## MarioM (Oct 6, 2011)

Hi to all. Good news. Finally my first engine runs....... 
[ame]http://www.youtube.com/watch?v=8x6S1hOGJD4&feature=player_embedded[/ame]

Had few mistakes. Alignment problems, leaks and friction. I used RTV to correct some leaks. Lapped the power cylinder and polished the piston. It seems it needs a lot of heat to run.......I have only used the torch.

Now it needs some cleaning, and a nice base. Very nice feeling to see it working!!!!!!!


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## lazylathe (Oct 6, 2011)

Congratulations Mario!!!!! ;D

How long will it run for when you remove the heat?
If it is not too long it still has too much friction and possible small air leaks.

If you disconnect the arms from the flywheel and push the power piston in and out does the displacer move?

I am sure the more you run it the less heat it will take to run!
My dream is that when i complete my first Stirling it will run off a tea light! ;D
We will see if that happens!!

Excellent job!!! Thm:

Andrew


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## danstir (Oct 6, 2011)

Good work and great perseverance!!


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## deverett (Oct 6, 2011)

Stan  said:
			
		

> Here is a hint for people who use the silicone type of gasket sealer.
> 
> Put a thin layer of sealant on to the cleaned surface and then set the object (sealer side down) on a piece off wax paper. Come back the next day and lift the object of the wax paper, trim away any that squeezed out and you have a gasket attached to one side of the joint but the parts will not be glued together permanently.



Stan, that's clever. Thanks for the idea.

Dave
The Emerald Isle


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## MarioM (Oct 8, 2011)

Thanks to all. I have learned a lot of things from this first engine. I realized need some extra tools to get some jobs done faster and easier. I will work the tools before I start a new project.


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## Harold Lee (Oct 8, 2011)

Mario,

Great work!!! I personally have a great appreciation for Rudy's designs. Please share your next project with us.

Harold


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## smuttley (Nov 3, 2011)

WOW that is a lot of heat.

I have put a new post up here http://www.homemodelenginemachinist.com/index.php?topic=16408.0 on tips and tricks on building and running Stirling engines. You look like you have done a nice job on this build and should not have any problem getting this baby running off a low flame alcohol burner. Also you should get around 500  800 RPM on alcohol and 1300  1800 on propane gas,

nice looking engine and hope you build more soon dude,

Smuttley


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## Springbok (Nov 4, 2011)

Hi
There is another thread in this forum I am sure will inrerest you
How to build and run a Stirling engine the first time out

Hope of some help


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## MarioM (Nov 5, 2011)

Thank you very much. Very interesting post.


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## Longboy (Nov 5, 2011)

Stan  said:
			
		

> I don't remember what plans I used, but I built a Stirling that looks like the one in the video.
> 
> ............My other problem was I used stainless steel for the hot end and SS has poor heat conduction...............


  SS is not considered a problem but rather an ideal material for the hot cap in Stirling for that reason, poor heat conduction. You are trying to heat the air with in the hot cap without the heat migrating to the body of the engine by use of lower conducting materials.


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## Stan (Nov 5, 2011)

I am completely lost on that comment. How do you heat the air inside the hot cap if the hot cap is not conducting heat?

Granted, SS will conduct some heat but require a much larger flame than a better conducting material. There is no real problem to heat isolate one component from adjacent parts.


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## smuttley (Nov 5, 2011)

Stan  said:
			
		

> I am completely lost on that comment. How do you heat the air inside the hot cap if the hot cap is not conducting heat?
> 
> Granted, SS will conduct some heat but require a much larger flame than a better conducting material. There is no real problem to heat isolate one component from adjacent parts.


No problem using stainless steel, just have to keep the wall thickness as thin as you can and this also goes for the end cap. I have been told that titanium is the best material to use, but never tried machining it before.


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## robcas631 (Nov 8, 2011)

Not yet but that will be project #2!


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## kilocharlie (Apr 30, 2013)

Well, it's now 2013....has anyone thought about making several cylinder heads (end caps) from different materials and seeing which one runs best? Should be a fairly cheap materials test with very real-world results.

Those of you looking to build Gamma-type Stirling engines for low-temperature differential power sources, design the displacer to be very large diameter with a very short stroke, and seek to minimize friction all over. Don't expect much power - power comes from cylinder pressure!

Does anyone know of an Alpha-type Stirling engine design parameter list? I'm hoping to start with "intended power output" and work from there. I'm aiming for fairly high torque, and my target is 15 to 20 horsepower. Thank you.


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