SpudFiles

check out the tippmann c3. it's a propane combustion pump action paintball marker. this design will help u with most of ur design. this link will show u how it works (4 pages total). i use this site alot for designing my projects.

http://www.warpig.com/paintball/technic ... ppmann/C3/

the C3 gave me the idea, but it uses a pump to cycle the fueling. a believe the nailguns also se the safety foot to cycle the action

ramses wrote:multiple ignition points

Like, multiple combustion chambers?
Kinda starting to look like an engine
"Hey dude, what's that?"
"Oh, this? It's just a 8-cilinder combustion cannon I built."

Tsukiten wrote:Like, multiple combustion chambers?

No... not quite. It's not uncommon to have a combustion launcher that has more than one spark gap in the chamber, meaning that the fuel is ignited in two (or more) separate places, increasing the burn rate.

i-will wrote:check out the tippmann c3. it's a propane combustion pump action paintball marker. this design will help u with most of ur design. this link will show u how it works (4 pages total). i use this site alot for designing my projects.

http://www.warpig.com/paintball/technic ... ppmann/C3/

a better animation of the c-3 can be found here.
http://www.zdspb.com/media/tech/animations/c3_2.gif

if u want to make a full-auto/semi-auto combustion then u'll need to focus some of that expanding blast into a separate cocking mechanism like an ak47. since it's airsoft the combustion chamber can be small and still deliver power.

or u can make a totally separate combustion chamber dedicated to recocking. it would work like a 2 cylinder engine except the exhaust is used as energy and not wasted. everytime a bb is fired with the first chamber the second chamber ignites and resets the first chamber and reloads a bb. then when it first ignites it'll reset the second chamber. back and forward in a chain reaction.

the most important part of this system will be the injection system.

it might be too much for a garage shop but it'll work if someone is willing.

the solution for injection, like stated above:regulated propane through solenoid valve, controlled by 555 with duty cycle tuned, through an aspirated burner to draw in air.

My current question is venting. The C3 and nail gun use the safety foot and shotgun style pump to vent or open the valve for venting. I really don't want to have to use a solenoid and more complex electronics. Any suggestions?

ramses wrote:Any suggestions?

Few that you'll particularly like.

There are ways where vacuum venting can be made more worth while, but they're a lot of effort - both to make and type out.

i-will wrote: or u can make a totally separate combustion chamber dedicated to recocking. it would work like a 2 cylinder engine except the exhaust is used as energy and not wasted. everytime a bb is fired with the first chamber the second chamber ignites and resets the first chamber and reloads a bb. then when it first ignites it'll reset the second chamber. back and forward in a chain reaction.

you make my head heart. it's a good idea, but if you recock the recocking chamber with the main chamber, why not just recock the main chamber with itself?

I wouldn't mind any suggestions on venting that make sense

ramses wrote:I wouldn't mind any suggestions on venting that make sense

Well, if you're not adverse to it, I have a design for a semi-auto combustion paintball gun (mind you, that's not surprising, I have plans for nigh on everything) - with a little electronics, but most of the mechanisms are handled by mechanical means - without any solenoid valves, other gas tanks for venting or that crap. Just a tank of propane and a few batteries.

It's even got an automatic metering system.
Tippmann would probably kill me for the design (best I know, they have no working semi-auto combustion prototype), but nyah to them.

It's largely older work of mine, but seeing your topic a few days ago inspired some improvements to it so it might yield a few shots per second. Building it down to airsoft size would be tricky, but converting it to full auto would just be a matter of automating the sparking.

However, bearing that in mind, it needs a higher than normal C:B ratio to ensure there's enough spare energy to work the auto cocking mechanisms, so you shouldn't build the chamber too small as it is, so airsoft size might be within practical limits.

It's not as fast, powerful or intricate as the hybrid BBMG idea I have which needs external tanks of air for venting and mix pressuriszation, but it is at least self contained.

Unfortunately, the downside is that I seldom draw any plans (I work in my head - for everything.), so I'd have to get busy on that front.
It will also need lathe work.

Interested?

YES, WE ARE INTERESTED

could a drill press, basic hand tools, and several hours wishing I had a real lathe be substituted for said lathe? If not, I will have to stick with the solenoid valves. Also keep in mind that my plans are rarely built.

I think Tippmann decided to go pump because of heat build up issue.

i like the c3 cuz it's a great example of venting and sealing the chamber. it's a pretty simple design that can be reproduced at home with the right tools. just find a way to modify it for airsoft and automatically pump the mechanism and ur done. u got a full/semi-auto combustion airsoft cannon.
and just like a real firearm, heat buildup will happen and might have an effect on the bbs if not cooled properly.

for those that don't know yet, i like to spit out ideas as they come to me. i'm not tryin to vex anyone. a private message told me otherwise.

ramses wrote:I think Tippmann decided to go pump because of heat build up issue.

Equally, a semi can be limited back to a certain rate, especially given that the C3's spark is electronically controlled.

The C3 claims 4 bps, which is about all I'd expect from a semi anyway.

could a drill press, basic hand tools, and several hours wishing I had a real lathe be substituted for said lathe?

If you can conjure up a couple of decent O-ring grooves on reasonably small diameter parts, yes. With those tools, I imagine you could come up with something - it might be possible to adapt the design more to your needs, within limits of course.
The thing is the parts need to be reasonably low friction to take advantage of what little energy is available.

Alternatively, the spool valve that's intended to run off chamber pressures could be modified to run off a beefy solenoid - that would also allow control of rate of fire. In practical terms, that might be the best option - although there is that appeal in doing it "the right way", with minimal electrical interference.

Whichever you prefer.

SEAKING9006 wrote:
YES, WE ARE INTERESTED

If that's your reaction to that, remind me never to show you the contents list for my ideas folder - I don't want to clean up the mess.
The semi combustion is small game.

Even the shell ejecting hybrid minigun doesn't really scratch the surface.

That ideas folder has got a few notes on each idea I have the ideas I have, mostly just to remind me I had it - the rest of the information is all locked in my head. (I've never really bothered with CAD programs - for most things, I can do it all upstairs, and with a hell of a lot less time and effort. The downside is that no-one else can see it.)

Still, don't get overly optimistic. The idea should work, but it's a little fiddly and not tested yet. Hopefully, you guys will be able to spot any errors I've made.

I can see I've consigned myself to drawing tomorrow.
But right now, it's bed time.

Ragnarok wrote:That ideas folder has got a few notes on each idea I have the ideas I have, mostly just to remind me I had it - the rest of the information is all locked in my head. (I've never really bothered with CAD programs - for most things, I can do it all upstairs, and with a hell of a lot less time and effort. The downside is that no-one else can see it.)

i know what u mean. it's all done in my head right away and i usually forget them pretty quick so i write them down. they r often not exact. the hardest part of it all is that no one really understands right away. and when they r not perfect right away then they get all critical instead of improving on the idea. i don't like closed minded nitpickers.