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btrettel
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Wed Sep 16, 2009 1:13 pm

lozz08, it doesn't matter if the force is constant. What matters most is energy. You can easily make a coil spring store the same amount of energy at the same displacement as a constant force device with some math and the right spring.

Some justification might be made for having a constant force device, but as this is a very complicated system I'd defer any conclusions until testing and/or calibrated simulations are done.
Last edited by btrettel on Wed Sep 16, 2009 1:52 pm, edited 1 time in total.
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jackssmirkingrevenge
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Wed Sep 16, 2009 1:23 pm

Or to put it another way, there's no such thing as a gas ram airsoft gun, and there's a reason for that ;)
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lozz08
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Wed Sep 16, 2009 9:02 pm

Well, I found a spring with a max force of just over 200N, at 12cm compression. This gives me 12 Joules of energy stored in the spring.If I wanted my four Joules out of the gun, I would then need 33.333% efficency. Can that be done?
btrettel
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Wed Sep 16, 2009 9:44 pm

Based on what I know, 33% efficiency is perfectly possible. It's worth noting that I'm basing this off one piece of data taken by someone who's wasn't extremely experienced in this, however, I see no reason to doubt the finding.

If you want a better idea of how efficient typical springers are, I'd suggest doing some testing. This will likely be an iterative process. You build one test gun, see how that does and if it fits your needs, and then adjust it or build a new gun as necessary.
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lozz08
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Wed Sep 16, 2009 10:02 pm

Yeah, I guess I'm a little caught up in trying to make it perfect my first time, when really I should just be doing a bit of trial and error. Thanks for the input. At least the only thing I'll be replacing each time is the power source, either spring or gas ram, as the body I'm making is able to be totally ttaken apart and all. I think I will try the spring first and make a gas ram while I'm at it, and see what works better.
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lozz08
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Thu Sep 17, 2009 5:30 am

OK, just a quick question to all you pneumatic dudez:

Lets say I have a magazine system, and I have 12 shots per magazine. If I wanted to make a portable bb pneumatic, could I fit enough air into a small tank in each magazine to get it to fire each one with around 4 joules? Cos if I made this pneumatic and have the air in each magazine it would be easier now wouldnt it :)
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jackssmirkingrevenge
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Thu Sep 17, 2009 5:58 am

You're beginning to see the light :)

What pressures are you willing to work with? Can you buy a CO2 or HPA tank with a regulator, or are you going to be pumping this by hand?
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lozz08
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Thu Sep 17, 2009 8:00 am

I really dont want to be paying a couple bux per mag for this, as co2 canisters are about that much. And I know buying bigger tanks is much less expensive but as I said I want to have the gas as part of each 12 rd. magazine.

I want to be having an integrated tank in each magazine that I can just refill with a powerful air compressor or something. I think the pressure will have to be large as its a pretty small area in each mag. You could maybe fit 2, 3 or 4 co2 canisters in there thats how small.
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Sat Sep 19, 2009 6:15 am

In that aspect you're right, a self contained springer is completely free to operate. How about a launcher mounted pump? That way, you don't have to worry about your air supply, only ammunition. It would be possible to have a single stroke pneumatic that with one pump pressurises the air and loads a new round at the same time.
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lozz08
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Sun Sep 20, 2009 1:41 am

I dont think a launcher mounted pump would be worth it, just because it would have to be less efficient and so there would be no real gain over spring piston. Im just gonna make a springer, wack a spring in there and see what happens as a first sorta experiment
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lozz08
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Sun Sep 20, 2009 10:21 am

Hey people, As I intend to make this gas ram at some stage, what is the best gas to use in the actual ram? should I just use air? Or would co2 or nitrogen leak less, or something, is there any actual difference?
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Sun Sep 20, 2009 10:25 am

Theoben rams use air. Airsoft guns use coil springs ;)
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lozz08
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Mon Sep 21, 2009 12:40 am

Yeah I dunno I just wanna make it exotic :)

Maybe fill it with hydrogen and see how that works out. Chick-chick- BOOM!
Self destruct mechanism.
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Mon Sep 21, 2009 1:02 am

lozz08 wrote:Maybe fill it with hydrogen and see how that works out.
You could have the piston powered by combustion, why not :) that would really be exotic :D
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lozz08
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Mon Sep 21, 2009 3:12 am

That would be kinda cool wouldnt it...

How about an integrated H-bomb launcher- I'd only need like a millionth of an ounce of plutonium and some hydrogen in each shell, and It would be pretty effective in airsoft skirmishes. If I could keep the blast radius to like 20M, and make it launch like 50m, it should be pretty safe.
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