Electro Powered paintball gun?

[Bucky]

well i was thinking more along the lines of an hydrolic (spelling) pistion that pushes some sort of cup shaped of half a paintball. now the pistion would push the cup with paintball in it down a barrel, such as a modern gun does the same thing. now this is just an idea, but instead of air doing the muscle working of moving the parts, the pistion would do that instead.

[nerobro]

It can be done. But, like in the last thread. All you need to do is do the math to figure out the energy necessary to fire a paintball and you'll figure out why we use compressed air ;-)

[athomas]

The energy used to power the paintball is stored in the compressed air. How does that energy get there? The compresser used to fill the bottle puts it there by transfering the energy from fuel (gas compresor) or electricity (electric compressor).

If your bottle gives you 1000 shots from your gun and you want 1000 shots from your electrically powered pneumatic gun, then your battery has to be able to provide the power to run a compressor to fill a bottle (same amount of energy used). If it can't then it doesn't have the necessary energy required to fire a ball either.

Note: A good battery doesn't have the required energy to fire more than a few shots, and these shots would have to be spaced out in time to allow the gun to fully recover from the previous shot because the battery couldn't deliver enough power fast enough.

The batteries running solenoids in todays guns barely have enough energy to release the stored energy in the compressed air let alone compress the air.

[nerobro]

Originally posted by athomas The energy used to power the paintball is stored in the compressed air.

Well.. Obviously. Right, the compressed air tank is just a battery.

If your bottle gives you 1000 shots from your gun and you want 1000 shots from your electrically powered pneumatic gun, then your battery has to be able to provide the power to run a compressor to fill a bottle (same amount of energy used).

Right, but the relation isn't direct. Compressors are mush less efficant. So even on the best of days you won't get more than say 80% efficancy out of a compressor. You'll need a more battery power.

Note: A good battery doesn't have the required energy to fire more than a few shots, and these shots would have to be spaced out in time to allow the gun to fully recover from the previous shot because the battery couldn't deliver enough power fast enough.

This utterly contridicts the measurement of battery capacity. Batterys are rated in amp hours. That's how much energy the battery stores. Period. Ah ratings are kinda amorphus, if you draw too much amperage from the battery you will get less energy from it. If you draw slowly you can get more than the rated power. This ties into the next point... AGD builds their battery packs to not need capacitors, and makes them so the gun does not outstrip the batterys rated discharge amperage. This is something you need to design for. (and is easy when you figure out how big of a battery pack you need to power one of these)

The batteries running solenoids in todays guns barely have enough energy to release the stored energy in the compressed air let alone compress the air.

This statment makes half sence. To release the energy stored in compressed air just requires a hole in the contanier. That's all. This requires no extra energy.

To put it in prespective, a nicad battery has less than 100mah capacity. An alkeline has somewhere around 220mah, but but you can't draw on it fast or else the battery looses most of it's capacity. You also run into problems with internal resistantce of the cells. With dry cells it's very high, and when you start to try to draw a lot of amerage the voltage drops hard.

On seartripping guns, they have a cap on there to help level out the power availalbe to the solinoid, and provide a high amperage power source. When fireing 20bps, the voltage on a dry cell drops down to around 5 volts. Versus the 9 it starts at.

A 9 volt battery can run a compressor so long as the compressors amp draw is low enough. but you'll never put in more energy than is in the 9 volt battery.

That's Where I was going with what i was saying. I feel like digging up the conversion from jules to watts. And that would give us the answer as to how much battery power we needed.

Anyone feel like digging up how much energy is behind a paintball?

[HoppysMag]

i donno if its been said but RAIL GUN!... i can picture that toms next post " guys we lost john today in a freak testing of our RMag221, aperantly well gave the system too much juice, who coulda known a paintball would pass through a concrete wall at March 3..." lol it could be done, youd just need to give the ball some polarity... mabey something in the paintballs fill.

[nerobro]

http://web.media.mit.edu/~aries/portable-power/node5.html#SECTION00030000000000000000

ah, i love seraching forums for the info I need... That url is a link to someone who did the math for us as for how much power a 1l n2 tank holds. 1l is a 68ci tank. so we're talking in the region of 12kwh. Say we go with a 6 volt battery pack. We're talking two thousand mah. This sounds reasonable. A 5 cell 2000mah pack could be easily assembled. Now, we need to factor in a few other things. First off electric motors aren't that efficant. And the pump it'll drive isn't very efficant either. And then, electric motors get less efficant as they warm up.

We are also assuming a gun that can get 1000 shots off a 68/3k

Going for homebulit, first run devices, probally the best we could hope for is half that efficancy? As soon as we get into gearbozes and electric motors, all bets are off. efficancy and calculations will need to be on a case by case basis.

[nerobro]

Rail guns dont' need polarity. they need a very very low resistance slug to pass electricty through. the injector speed for rail guns seems to be in the 100 fps range.. and they use compressed air to inject the projectiles.

to do this you'd need conductive paintballs... VERY conductive.

[HoppysMag]

Originally posted by nerobro
Rail guns dont' need polarity. they need a very very low resistance slug to pass electricty through. the injector speed for rail guns seems to be in the 100 fps range.. and they use compressed air to inject the projectiles.

to do this you'd need conductive paintballs... VERY conductive.

and im lost.... your saying the rail gun just accelerates an object? doesnt actualy get it moving just boosts it? um ok... i thought it worked like those japanesse trains... same polarity behind an object pushes it away while oposit polarity infront pulls it too.. then as it gets over top, it goes nutrual and then switches to same polarity to push it onward to the next um... magnet i guesse... im probibly wrong but is there any truth to that

[nerobro]

You're thinking about a gauss gun. A linerar electric motor of sorts.

Rail guns operate on a different theroy. Lorenz effect IIRC.

[athomas]

nerobro:

I was commenting generically on the the ability to use stored energy to do work. Everything is a transfer of energy. No transfer of energy is 100% efficient but I didn't want to calculate every exact joule of energy used in each process just to explain an idea.

The reference for the "gun" not being able to recover fast enough was because the battery probably couldn't power a compressor to compress the air fast enough. Ie; the same as your reference to the 9v battery running a compressor.

Ah ratings are kinda amorphus, if you draw too much amperage from the battery you will get less energy from it. If you draw slowly you can get more than the rated power.

Most batteries are not rated for the energy that they hold. They are rated for the useable energy above a determined thresh-hold. The fact that the battery still contains energy below this point is ignored in the rating. Because the battery delivers power more slowly, it is more likely to be able to chemically generate the electricity required for a stable current draw from the cell(s). For the most part, the useable ampacity of the battery will be the same whether the current draw is high or low. The current draw can only be as high as the battery can produce or you get voltage drop.

[nerobro]

Try drawing five amps from a dry cell and find how much total power it delivers. then try drawing at a few microamps. you'll see a huge difference in capacity. Same goes for nicads. Draw 50 amps from a nicad cell and you'll generate a lot of head, an get a lot less electricty out of it. Draw one amp, and you'll get at least the rated capacity if not more.

There are more effective ways of getting electrical energy into a paintball rather than running a compressor... But I don't know how effective they are.

Either way, I think this is a dead end discussion. I'ts been hit before a few times in deep blue. Do you want to carry a heavy battery pack? or a relitively light air tank.

[athomas]

Originally posted by nerobro
Try drawing five amps from a dry cell and find how much total power it delivers. then try drawing at a few microamps. you'll see a huge difference in capacity.

The capacity will still be there You'll just have to wait for the cells to cool to produce the rest of the electricity.


You can't draw more than the rated instantaneous load capability of the cells. Thats like saying I have the power of the sun at my fingertips, but I only have this tiny skylite with which to let the sun into my room.

That being said, 1 Amp hour drawn at 1 amp over a one hour period is the same as 1 amp hour drawn at 200mA over the period of 5 hours.


I think we all agree the idea of using a battery to compress air in real time is not an efficient way to go.

[314159]

Originally posted by athomas

Most batteries are not rated for the energy that they hold. They are rated for the useable energy above a determined thresh-hold. The fact that the battery still contains energy below this point is ignored in the rating. Because the battery delivers power more slowly, it is more likely to be able to chemically generate the electricity required for a stable current draw from the cell(s). For the most part, the useable ampacity of the battery will be the same whether the current draw is high or low. The current draw can only be as high as the battery can produce or you get voltage drop.

Power = Amps x Volts

the more amps you draw out of a battery, the more the voltage drops

the maximum power you can draw from a battery, is when you draw enough current out of the battery, to drop the batteries voltage to half of it's voltage when nothing is connected to it.

[athomas]

Originally posted by 314159


Power = Amps x Volts

the more amps you draw out of a battery, the more the voltage drops

the maximum power you can draw from a battery, is when you draw enough current out of the battery, to drop the batteries voltage to half of it's voltage when nothing is connected to it.

Exactly. That's the true capacity of the battery.

[HoppysMag]

Originally posted by nerobro
You're thinking about a gauss gun. A linerar electric motor of sorts.

Rail guns operate on a different theroy. Lorenz effect IIRC.

yup thats what im talking about then... cause i had to explain oit to some one once and thats how i explained it... like cuting open a motor and unroling it