# My engines  (LTD and Lamina Flow Stirling Engines)



## PalmRunner (Jan 22, 2008)

Hello everybody. 

Check out the pictures and videos of my engines, could be of interest to some of you. They are made using very basic tools (no lathe, no plans). Some parts are taken from the local hobby shops and reprocessed to fit my needs.

My first engine is an LTD Stirling able to operate on a very low temperature difference. In the very first version I used a rubber diaphragm cut from surgeon gloves. Watch the video here:
http://video.google.de/videoplay?docid=-6017180985879911654
It worked well, but the rubber shows signs of ware / ageing, so I replaced it by an Airpot piston/cylinder set. 
With this, I was successful to run the engine on the cooling effect of evaporating water (less than 2C temperature difference)!
See pictures from the improved version here:
http://picasaweb.google.com/PalmRunner/LTDStirlingEngine

This is my second engine. 
[youtube=425,350]cjjkj-UGboM [/youtube]

Lamina is wrongly referred to a thermoacoustic device, but in any case it is the most simple power producing engine. With the last modification (reduced test tube volume) Lamina reached 1800 RPM powered by an alcohol burner and over 1000 RPM heated by a candle flame.
See some pictures here:
http://picasaweb.google.com/PalmRunner/LaminaFlowStirlingEngine

Cheers,
_________________
*- PalmRunner * 
I know enough to know I don't know enough!


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## mklotz (Jan 22, 2008)

Ausgezeichnet! Very impressive for first engines.

Why do you say "Lamina is wrongly referred to a thermoacoustic device"? I thought these engines operated by virtue of an acoustic wave serving as the energy transport mechanism.

Since I'm planning on building one as my next engine, I'm interested in hearing more construction details. Do you have plans available for Lamina?


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## 1Kenny (Jan 22, 2008)

PalmRunner,

Welcome to HMEM. You have made some very nice engines. I am liking the one with the ball bearing flywheel.

Kenny


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## Kactiguy (Jan 22, 2008)

Great engines. That Lamina really gets moving. Nice job.


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## PalmRunner (Jan 22, 2008)

Thank you guys for the nice words!

Marv,
A lot of interesting discussions about Lamina you will find in the yahoo HAES group http://tech.groups.yahoo.com/group/HotAirEngineSociety This engine is discussed very often and there is no good explanation yet, but the common agreement is that the engine is not a thermoacoustic device. Perhaps, the name comes from the visual resemblance to a science kit sold as a thermoacoustic laser. The main problem to apply the thermoacoustic theory is that the test tube is too short to maintain resonance at such low speeds. Most engines work at speed less than 1000 RPM which is ~16Hz. To have a resonance at this frequency youll need maybe 2 meters long test tube (resonator). The other problem is that if the resonance was what moves the piston, then the engine would stop as soon as you put some load and bring the speed outside the resonance frequency, which is obviously not the case  the engine runs at 100 RPM (when loaded) as good as at 1800 RPM. If you are interested about this engine I would recommend you to read the Peter Tailers patent about Thermal Lag Machine, which is actually the origin of Lamina engine.
http://www.google.com/patents?id=wngjAAAAEBAJ&printsec=abstract&zoom=4&dq=patent+5414997#PPA2,M1

The explanation there is not so good, but youll get some impression about how it works.

About the plans  actually I havent used any, but can give you the details about some important dimensions of the latest Lamina version:

Test tube: 
Length - 100mm 
Internal Diameter - 11mm 

Regenerator: 
Material - very fine steel wool. 
Occupies ~2/3 of the test tube.

Restrictor (the opening between test tube and power piston):
Diameter ~ 5.5 mm
Length ~ 7mm

Power piston: 
Material - graphite 
Diameter - 16mm 
Stroke - 30mm 

Flywheel: 
Diameter - 90mm 
Weight - 200grams
Mounted on miniature ball bearings.

Speed: 
Heated by a tee light: over 1000rpm. 
Heated by a alcohol burner: up to 1800rpm 

Measured shaft power: 
40-50 mW (not very precisely measured) 

The restrictor is a very important part and it is in my engine just by a chance. Simply, the mounting stud of the Airpot piston/cylinder set is playing this role.At first I was not aware about the need of this detail and thought it would be much better if there is no such restriction, just straight test tube with a piston at the end. Later I realized (from the other Lamina fans) that this is actually a very essential part without which the engine would not run at all.

Regards,


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## mklotz (Jan 23, 2008)

Many thanks for the information, Palm. I've copied your post to my shop notebook and I'm sure it will be useful as I design my own engine.

I was aware of the importance of the restrictor but wasn't sure about how to size it. Now I can scale from your (known to work) engine and another design that I found on the web.


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## Brass_Machine (Jan 23, 2008)

I appreciate the info too as well, PalmRunner. My test tubes just arrived yesterday 

Eric


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## DICKEYBIRD (Jan 23, 2008)

Hey Eric, where did you source your test tubes?

Thanks,
Milton


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## Brass_Machine (Jan 23, 2008)

DICKEYBIRD  said:
			
		

> Hey Eric, where did you source your test tubes?
> 
> Thanks,
> Milton



Ebay!. Got a dozen for $0.99. Do a search for "testtube" and "pyrex"


Eric


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## Powder keg (Jan 23, 2008)

Hey Palm, Great engines!!! The LTD with the spokes with weights on it is interesting. Do you have a video of it running? Thanks for sharing your engines. I'd like to build one of those Lamina Flow engines next maybe?

Thanks, Wes


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## shred (Jan 23, 2008)

Test tubes can also be found at Hobby Lobby and Frys, but the quality/selection is a little suspect.


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## PalmRunner (Jan 24, 2008)

Hello guys,
I'm glad I can help you with the little experience Ive gathered when building Lamina. Fascinating engine, amazing that so simple thing works at all.
BTW, I updated the Lamina pictures with the latest version of the engine:
http://picasaweb.google.com/PalmRunner/LaminaFlowStirlingEngine
Youll see the smaller volume test tube that I am using now.

Wes, I dont have a video of my latest LTD yet, but I am planning to upload soon. The trick with weights on the spokes I found to be an easy way to balance my engine. And ... I think it also looks nicer in this way.


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## Powder keg (Jan 24, 2008)

Can't wait for the Video:O) How big are the top and bottom plates on your work of art? By the way, Welcome to the forum. 

Wes


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## PalmRunner (Jan 25, 2008)

Powder keg  said:
			
		

> How big are the top and bottom plates on your work of art?



Hi Wes,
The plates on my LTD are155mm. The displacer cylinder is ~135mm ID.
Regards,


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## Powder keg (Jan 25, 2008)

II thought it looked bigger than that? 

Thanks, Wes


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## PalmRunner (Feb 27, 2008)

Hi guys,

Ive made a short video of my LTD. Here it is:

[youtube=425,350]5Mbz5VXlhls[/youtube]


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## kustomkb (Feb 27, 2008)

very nice! I wish mine could run on a differential as low as that.


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## Powder keg (Mar 2, 2008)

You did a great job on that Palm! I'm still trying to get mine running again. 

Wes


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