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Cold Powered Propellant Alternatives?

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Kruegon

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If this topic is on here, I couldn't find the right search string to locate it. Sorry if it's been covered before.

I've been looking at getting the parts to clone a cold powered rocket. Obviously the R-12 is banned by federal order. So what could be used legally to launch one?

All research points to the requirement of an inert liquid fuel that converts to gas at room temperature. Pressurized liquid CO2 could work, but doesn't seem viable. Obviously liquid nitrogen could be considered, but the dangers if there's an accident seem not worth it. I'm currently considering the canned airbrush propellant and the compressed "air" canisters.

Has anyone tried these? Do you have other suggestions that have been tried successfully? Thanks.
 

Screaminhelo

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I have never messed with the cold powered stuff, how much pressure do you need? It has been quite a while but I don't think that the canned air will be much over 30 psi as most airbrushing is done at 25 and below.
 

rstaff3

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I remember seeing that someone studied various propellant alternatives. It wasn't too terribly long ago. I forget whether it was here, on YORF, in a magazine???
 

Mugs914

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I haven't played with cold power since I was a kid in the seventies! Brings back great memories of Estes rocket cars (Google "Estes Land Rockets") and foam rocket gliders.

I know that the R-12 is gone now, but you might try the new formula airbrush propellant. Not sure what it is, chemically, and you need to flip the can over to dispense liquid rather than gas, but it seems to have the same basic properties as the old stuff. I've got a can on my bench and had to go mess with it after reading your post. I think it might just work...

I don't know anything about the "canned air" keyboard cleaner stuff, except that I don't think it comes with any kind of attachment fitting on the can.

Do you have any of the old engines or are you thinking about making your own? Be sure to start a thread on your progress. I'll certainly subscribe!
 
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Kruegon

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I have managed to locate some people willing to part with some of the cold power stuff.

I'm definitely not going to try tooling my own motors just yet lol. But if I had that ability, at least I could custom tool it to work on current formulations and pressures.

I'll keep everyone updated as this progresses. Revival of the ancient rocketry ways. The SCR, Society for Creative Rocketry. Preserving and recreating the history of model rocketry.
 

gpoehlein

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I haven't played with cold power since I was a kid in the seventies! Brings back great memories of Estes rocket cars (Google "Estes Land Rockets") and foam rocket gliders.

I know that the R-12 is gone now, but you might try the new formula airbrush propellant. Not sure what it is, chemically, and you need to flip the can over to dispense liquid rather than gas, but it seems to have the same basic properties as the old stuff. I've got a can on my bench and had to go mess with it after reading your post. I think it might just work...

I don't know anything about the "canned air" keyboard cleaner stuff, except that I don't think it comes with any kind of attachment fitting on the can.

Do you have any of the old engines or are you thinking about making your own? Be sure to start a thread on your progress. I'll certainly subscribe!
I've looked into this a bit (I have an old Valkyrie that I got at auction several years ago). If you use airbrush propellant, check the label. You CAN use it, but if it contains petrolium products, it will be flammable. You can manually launch with it (ie pull the pin yourself) but do NOT electrically launch it. An I believe most airbrush propellants (including every brand I have seen) do contain petrolium distillates. That was the beauty of the old CFCs - they were not flammable and they were liquid under pressure, so you could put more active propellant in the tank. CO2 does not compress the same way, and makes a very limited propellant.
 

Kruegon

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The petroleum content is a very good point. Thanks for bringing that up. The search for a safe and legal alternative will continue. I know there was a gentleman at NSL this year that attempted to launch one. He had a failure though. I'll check to see if anyone has his contact info. Perhaps he can enlighten us as to what he was using as propellant.
 

JumpJet

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If someone ever runs across such a propellant that the environmentalist won't go nuts about I would love to hear about it. I think that would be a great product for Estes to bring back. For a short time I worked at an air conditional manufacturing company here in Pueblo so I inquired back then about a possible replacement but there wasn't one.

John Boren
 

K'Tesh

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Revival of the ancient rocketry ways. The SCR, Society for Creative Rocketry. Preserving and recreating the history of model rocketry.
Where do I sign up?
 

Charles_McG

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Based on the boiling point and vapor pressure, the canned 'air' R134a should be an option for replacing the R12 - as it was as a refrigerant.

More exciting alternatives might be propane or ammonia. Both have vapor pressures near the CFCs. One is flammable and the other toxic. Very exciting.

Both N2O and CO2 have vapor pressures 10 times higher. I imagine that either the motor has to contain it - or it vents to self refrigerate - and limits its own pressure.
 

dhbarr

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Based on the boiling point and vapor pressure, the canned 'air' R134a should be an option for replacing the R12 - as it was as a refrigerant.

More exciting alternatives might be propane or ammonia. Both have vapor pressures near the CFCs. One is flammable and the other toxic. Very exciting.

Both N2O and CO2 have vapor pressures 10 times higher. I imagine that either the motor has to contain it - or it vents to self refrigerate - and limits its own pressure.
Lipo battery, thermocouple, resistance coil? I'd have to run the numbers but it seems achievable for CO2. The appeal there of course would be an aluminum case reloadable w/ a certain weight of readily available dry ice pellets.
 

Kruegon

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Based on the boiling point and vapor pressure, the canned 'air' R134a should be an option for replacing the R12 - as it was as a refrigerant.

More exciting alternatives might be propane or ammonia. Both have vapor pressures near the CFCs. One is flammable and the other toxic. Very exciting.

Both N2O and CO2 have vapor pressures 10 times higher. I imagine that either the motor has to contain it - or it vents to self refrigerate - and limits its own pressure.
My only concern about the R-134a is the fact that it's technically an oil based substance or contains an oil as a portion of its formulation. What would the oil do cold powered motor?

My biggest concern with CO2 is a question of required pressure vs volume in consideration of the motor's tolerance. Simply achieving lift-off does not resolve the propellant issue. We need to find an alternative that will provide equal or better results than the Freon.

I'll keep looking at the options and expansion rates.
 

Kruegon

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Where do I sign up?
Right now it's a very select group. Only one member has joined lol.

It wouldn't be a bad idea. A group on Facebook dedicated strictly to collecting, building, and flying OOP kits and clones. We'd need to start a new database of instructions, decals, templates, and RockSim files just for it. Time to beg, borrow, plead, and steal to build it up in one location.

You in?
 

Kruegon

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If someone ever runs across such a propellant that the environmentalist won't go nuts about I would love to hear about it. I think that would be a great product for Estes to bring back. For a short time I worked at an air conditional manufacturing company here in Pueblo so I inquired back then about a possible replacement but there wasn't one.

John Boren
I'm on it. We'll need to look at possible formulations, environmental impact, performance differences, toxicity, and flammability.

If I find anything that seems viable, I'll get with you on it.
 

RocketFeller

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I'm on it. We'll need to look at possible formulations, environmental impact, performance differences, toxicity, and flammability.

If I find anything that seems viable, I'll get with you on it.
That is a great idea. I come across old kits fairly often, as people bring me rocket stuff fairly often - I run an after-school rocketry club at my school. That said, the history of model rocketry isn't my thing, so they end up collecting dust in my already overloaded garage or rocket cabinet at school.
 

Kruegon

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That is a great idea. I come across old kits fairly often, as people bring me rocket stuff fairly often - I run an after-school rocketry club at my school. That said, the history of model rocketry isn't my thing, so they end up collecting dust in my already overloaded garage or rocket cabinet at school.
If your up to donating rockets, or info, to the cause, I'm already actively building a collection to start a website. Most of the other sites have fallen into disrepair. I'm quite serious about this endeavor.
 

RocketFeller

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I imagine that I might have some older rockets that you would be interested in. Rocket Club doesn't start again until spring, so they are mostly boxed up. When I get a chance I will snap a few photos of what I have.
 

mwtoelle

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Propane has been used to replace R-12 in some auto air conditioners. I believe that canned air would also work. R-134a would need compatible hose since that molecule is much smaller than the R-12 molecule. IOW, R-134a can leak through the R-12 hose material itself.
 

Tonimus

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I would use the R-134a or Canned Air. Should be very similar stuff, chemically. If you use R134A, you can use a squeeze-on can clamp or turn it upside-down for liquid dispensing. If you refrigerate (freeze) the motor, you'll get more liquid in it that way.
 

Kruegon

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Is the motor removable from the rocket? Would be a major boon if it was. That would definitely allow you to chill the metal pre-flight.
 

Kruegon

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I would use the R-134a or Canned Air. Should be very similar stuff, chemically. If you use R134A, you can use a squeeze-on can clamp or turn it upside-down for liquid dispensing. If you refrigerate (freeze) the motor, you'll get more liquid in it that way.
I just got my hands on the instructions last night. Chilling the motor isn't the way. Yes it may allow more fluid, but it's stated that the motor needs to be warm. Apparently, a cold motor effects performance adversely. So that's out. Not to mention the fact that the motor has a blow off valve for excess pressure. So it has a limited pressure it can function under.
 

Tonimus

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What's the blowoff valve rated at? If it is high enough, chilling is could still work, just allow it to come back to room temp before use.
 

Kruegon

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What's the blowoff valve rated at? If it is high enough, chilling is could still work, just allow it to come back to room temp before use.
I haven't found the specs for the valve. And they really aren't a "load and hold" motor. You don't charge the motor until it is on the pad and ready for flight. The Vashon has the motor as being the BT also and uses a plug that is also the "igniter". The Estes uses a charging and manual release block as an all in one. And apparently, even when brand new, the motors will slowly leak down pressure as they sit.

It's quite an interesting set of circumstances that have to come together right for a successful launch. Could be part of the reason they weren't more popular. I imagine that it only feels complicated the first few flights. After you're comfortable with the system, it's probably no big deal. Just like building RMS motors.
 
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