# CO2 Engine



## putputman (Apr 16, 2009)

I have been challenged by my son. He would like me to build a small engine that could be run with a small CO2 cartridge. It will be used as a paper weight on his desk at work and be used as a bragging tool of his "old mans" skills. _They really know how to get to you, don't they_.

I was thinking of a version of Elmer's Tiny or Kerzel's CO2-V engine or something like those.

My question to you is: has anyone come up with a way to use those small CO2 cartridges for this purpose. There must be a safe way to contain the cartridge, puncture it and regulate the air. I would like to be able to hide this mechanism in the base for the engine.

Would those small cartridges even work for this application? ??? ??? ???


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## mklotz (Apr 16, 2009)

Some alternate thoughts...

Those canned air cylinders sold to blow dust out of electronics, etc.

Those rechargeable spray cans that have a Schraeder valve for pressurizing.

Make one from a small propane tank (Coleman lantern size) - fit with throttle valve and Scraeder valve for recharging at any gas station.


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## Lew Hartswick (Apr 16, 2009)

I think the tinny CO2 airplane engines that Bill Brown designed and built used those.
That was along time ago so not completely sure. Should be able to search those 
terms and find something. 
  ...lew...


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## rickharris (Apr 16, 2009)

A standard PEt soda bottle will easily hold 80 PSI. Pressurise with a hand or foot pump.

http://www.ast.leeds.ac.uk/~knapp/rockets/ some example information.


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## shred (Apr 16, 2009)

You might go by a homebrew supply store if there's one nearby-- they had a selection of small CO2 regulators and plumbing at the one I was in not long ago, including holders for the little disposable tanks.

I presume by 'CO2', you mean 'handy source of reasonably benign compressed gas to run an engine on', and not specifically 'I want to inject liquid CO2 into a cylinder and have that expansion pressure drive the engine' (does anybody even do that? Seems like it might be an interesting exercise, though much more complex than an air engine)


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## Kermit (Apr 16, 2009)

Those handle pumped air rifles(pellet guns) are pretty cheap. The ability to "recharge" the propellant in the field might make that a mechanism worth considering.  The reservoir is fairly compact, you'd just need to make a holder for the pump and handle. Just remote-locating the reservoir and leaving the gun together might be an option.


Thoughts are cheap, ;D
Kermit


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## cobra428 (Apr 16, 2009)

You could use Propell. Check the hobby shop or art store. It's use for airbrushing. Hose has a shut off valve at the can.
Tony


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## wespe (Apr 16, 2009)

If you are thinking of using the small 12gram cartridges found in sporting goods stores, you may want to check out some of the paintball equipment that you could adapt to run the engine. A part such as this:





will pierce the cartridge safely and should run your engine for a while. Couple that to an adjustable regulator and you would have a very compact and adjustable set up. 

I can give you some actual part numbers if you would like, just say the word.

-Tom


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## kf2qd (Apr 16, 2009)

A needle valve would probably do the job instead of a regulator, and a length of tubing (like capilary tubing from an Air Conditioning shop) coiled would act as a heat exchanger so the engine would run on gaseous Co2 instead of liquid (would probablt frost up if any liquid made irt to the engine)

You could also look up some information on Free Flight CO2 airplanes. Basically they use CO2 for a pressure source because it give much higher volume that air pressure does because you are using liquid CO2 in the tank.


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## kvom (Apr 16, 2009)

At room temperature a tank of liquid CO2 is at ~850 psi, so no one will be "injecting liquid CO2" into their engines. Rather, the space in the tank that does not contain liquid is gas at 850 and is released by a regulator at a lower pressure. The cartridges used in paintball guns and the like are just miniature tanks.

You can obtain 1 pound CO2 tanks with built-in regulators at Lowes, and can refill them when needed.


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## cfellows (Apr 16, 2009)

You can also check out ebay. Lots of CO2 regulators and accessories for sale there...

Chuck


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## cfellows (Apr 16, 2009)

I've often wondered how long a small engine would run on a 12 gram CO2 cartridge. These can be bought at Walmart in boxes of 25 for about $12.50. I buy them for my CO2 air rifles all the time. I also have a 7 pound CO2 tank that I got filled at a homebrew beer making store. Cost me about $16 and will last me forever!

CO2 can be dangerous if the ambient temperature gets above 110 degrees. With a 100% rated fill and 120 degrees, the pressure can rise to over 2,000 PSI so I keep my CO2 tank in the (air conditioned) house during the summer. Here in Arizona, the garage temperature can get up to 115 in the summer.

Here is a graph of CO2 pressure vs temperature...


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## kvom (Apr 16, 2009)

I have a 20# tank that I bought for airing up tires when offroading. I've also used it to run air tools. Fillup once a year or so for $20 at a welding supply store.

When I was doing the interior finishing of my shop I used it a lot to run nail guns.


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## Metal Butcher (Apr 16, 2009)

I tried the idea of using a disposable CO2 cartridge to run my 'Modified Oscillating Wedge" motor.
I'm sorry to say that unless you try to use a poppet valve or piston valve it won't run a motor for more than several seconds. Its very difficult to control 900 psi. I made a very restrictive valve on the motor in my effort.

I haven't tried the poppet or piston valve mentioned above above to say for sure, but there were small CO2 powered air plane motors commercially available at one time. I think they were 020.

The link below will lead you to the motor I built along with its CO2 cradle. Its the red colored one.

http://www.homemodelenginemachinist.com/index.php?topic=4707.0

EDIT: The final solution was to drill a spent CO2 cartridge for an air line fitting.

-MB


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## putputman (Apr 16, 2009)

GEEEEZ, I thought what he was asking for was simple. I guess we are going to have to sit down, with a cool one, and discuss this whole project again.

The last time I played with CO2 cartridges was when I was a kid, and that was a long long time ago. A friend of mine and I had little race cars that were propelled with CO2 cartridges.We would load the cartridge into the cars, puncture the cartridge with a tool similar to the one shown in Tom's "wespe" post, and let them go. They would go for almost a full city block and faster than we could run. Now that I think back, they were frost covered when we got to them.. Forgot about that.

I think MB's experience tells me that these small cartridges would not last long enough to do what we were counting on. It is possible that there is a safety problem and he wouldn't be allowed to have these cartridge in his office.

Thanks to everyone for the feed back. This isn't over yet, so keep the ideas coming. Some of these small fillable cartridges might be the answer. Obviously, safety has got to be first.


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## Metal Butcher (Apr 16, 2009)

Not sure if my suggestion is to far off what you or your son had in mind. It could be a simple solution that would be acceptable.

Small inexpensive aquarium air pump. The vibrating diaphragm type.
The engine would need to be small. Say, 1/4" -or- less bore wobbler?

I wonder if it could work? 

Has anyone out there tried this?

-MB


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## GailInNM (Apr 16, 2009)

Arv,
For an office type engine you might consider a Low Temperature Differential Stirling engine. Once they are tuned, they are quite reliable and there is almost always a cup of coffee around to run one with. May be more work to build than you want however.
http://www.homemodelenginemachinist.com/index.php?topic=3621.0
Gail in NM,USA


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## mklotz (Apr 16, 2009)

Stirling is a great idea. Make sure you weld a chain to the cold plate. They have a tendency to go walkabout.

Another possibility is the Duclos Huff 'n Puff - breath powered. Many small engines can be run from breath power (maybe not an oscillator). The problem is not so much pressure as capacity. If your son plays the French horn, no problem.


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## Metal Butcher (Apr 16, 2009)

Not in the mood to solve the problem?

Tell him you worked on the project in secret! 8)

http://cgi.ebay.com/COMPLETELY-Polished-Stirling-Engine-Kit-no-Steam_W0QQitemZ170322079692QQcmdZViewItemQQptZUK_Trains_Railway_Models?hash=item170322079692&_trksid=p3286.c0.m14&_trkparms=66%3A4|65%3A10|39%3A1|240%3A1318

Simple solution to a simple problem! ;D

-MB


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## shred (Apr 16, 2009)

kvom  said:
			
		

> At room temperature a tank of liquid CO2 is at ~850 psi, so no one will be "injecting liquid CO2" into their engines. Rather, the space in the tank that does not contain liquid is gas at 850 and is released by a regulator at a lower pressure.


I was thinking that if you wanted to do that, you'd feed from the bottom of the CO2 tank (let the vapor pressure do the work for you) and have some high-pressure valving... with a small enough valve surface area, the forces could be reasonable. Anyway, nobody seems to want to do that in this thread, so the point is largely moot.


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## putputman (Apr 17, 2009)

I must have tunnel vision. As my son & I talked about this project, I forgot about all other possibilities.

Gail, thanks for the reminder.

Within the last month I had ordered Jerry Howell's "miser" low temp stirling engine kit with son extra bearings. (Incidentally, he does not include the acrylic ring anymore). I also purchase the acrylic tube from McMaster Carr. 12' length is the minimum. I have enough for several engines.

Marv, as far as the engine "getting legs" I understand that is a problem with just about anything left open in an office today. Too bad!!!


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## cobra428 (Apr 17, 2009)

I found this in my model airplane engine cabinet way, way, way in the back!










Tony


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## putputman (Apr 17, 2009)

Tony, can you explain how it works? Do you charge the cylinder on the right and it goes with the airplane? I have never seen anything like this. How long would it fly? 
Are these kits still available?


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## GailInNM (Apr 17, 2009)

Arv,
Here is a web site that has a lot of info on CO2 engines.
http://blacksheepsquadron.com/

I also have a couple of G-MOT CO2 engines here. Used to fly CO2 free flight starting back about 1953.

An EBay search for "CO2 engine" shows about 15 CO2 engines listed at the moment.

Gail in NM,USA


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## cobra428 (Apr 17, 2009)

Hi Putputman,
Yes, I use to fly FF CO2 too, but it wasn't till 63. 1953 I was fresh out of the oven  The orange thing on the left is the charger. You put a soda cartridge (which you can't get anymore, I don't think). You charge the system by taking the filler (orange thing) and pressing it against the orange fill valve (check valve) at the end of the tube coming from the other cylinder. You would hold the filler so that the nozzle was down and let the liquid into the other cylinder. That's it, your ready to fly  Gail you are going to have to help me out on this....30-40sec run time depending on rpm setting? The funny looking wrench on the right was for adjusting the RPM. The nut just behind the prop was the adjustment. That about sums it up.

And Gail you stole my thunder again, I was going to show that site Rof} I knew there was something I liked about you. Your an airplane guy too :bow:

Tony


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## GailInNM (Apr 17, 2009)

An animation of a CO2 engine is at:
http://www.animatedengines.com/co2.shtml

Tony, I never saw a Telco up close so can't make much comment on it. I saw some plans somewhere for a CO2 engine that used an eccentric bearing for the crankshaft so the crankshaft could be moved up and down to vary the timing so I suspect that was how the regulation you were talking about worked. BTW that was done on at least one commercial compression ignition engine to vary the compression ratio for timing as opposed to using a contra piston.

The only CO2 I flew was the OK Cub engine that was larger and used the entire CO2 cartridge for power. I got the G-MOT engines to play with when I was flying micro electric RC, but never got around to doing anything with them.

Gail in NM,USA


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## cobra428 (Apr 17, 2009)

Gail, your killing me here. OK Cub holey shirt! I didn't have the CO2, I had a glow .049 for FF/CL. Next your going to talk about a Herkimer, McKoy and then Dynimite, O&R.... Have to stop we are stepping on this thread. We will have to start a side bar of nostalgic antique model A/C motors! Sorry Putputman
Tony


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## sparhawk817 (Aug 13, 2013)

i know this is years too late, but for future people finding this thread looking for helpful info, a ball valve would work just fine, check out http://www.animatedengines.com/co2.html for visual help. i'm using it and canned air to power my bike.


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