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Auto Combustion Discussion

Posted: Wed Mar 15, 2006 4:41 am
by CS
Please stay on topic!
[Originally posted on spudshot.com, then slightly edited, then posted here to get more traffic]

Ok I’ve been chasing the idea of an auto combustion for quite a while now. Surely it could be done with high tech electronics, lots of money, electronic solenoids, timers, pneumatic cylinders, etc. This is being posted so that we can provide solutions to problems faced in making an auto combustion, and hopefully this will speed up the time that it takes one of us to make an auto combustion.

The way I approach problems is to list the things needed to be accomplished then design something that will accomplish just that.

Components needed:
  • Loading mechanism
    Venting mechanism
    Fueling mechanism
    Igniting mechanism
    And normal components such as barrel, chamber, etc...


Process procedure:
  • Load
    Fuel
    Ignite
    Vent
    Repeat


This isn’t necessarily how the process needs to go, but your going to have a different concept in nature to “toss” up the order of the procedure.

I think when its broken done this way its much easier to understand and to design around.

Discussion of how such a item would be constructed/ operated:

Loading:
Loading needs to be the first step because something needs to contain the fuel within launcher. Since in my set up loading will be first. Thus, the first shot cannot be powered by a mechanism driven by the combustion (blow back). So a “manual” force or a different force such as a pneumatic cylinder will be required to load the first shot. Also spherical ammo should be used because other shaped ammo will only add to designing difficulties. Although the problem with spherical ammo is that it usually is a low friction fit and light, not creating enough back pressure to drive a loading mechanism. This mechanism could be ran by a either forces from combustion (a blow-back mechanism) or a separate power such as a CO2 operated pneumatic cylinder.

Fueling:
If such a cannon was constructed I think an electronic solenoid on a 555 timer would be the best way to go because it would give you consistent fuel amounts. The timer would be synced by connecting a contact switch to a point in the loading process. Once contact switch is connected then the solenoid will open immediately, run for 3 seconds, then shut off.

Igniting:
This also might be run on a 555 timer switch, which would be set off by the same contact switch. Say that the fueling process took 3 seconds, and then you could set the timer for the ignition (stun gun would be the way to go) at 4 seconds. The duration would only be say half of a second. This means it would detonate a second after fueling sequence is completed.

Venting:
This would again also be set on a 555 timer. Once the contact switch in connected it will delay for 5 seconds then run for an undetermined amount of time, then shut off. You would vent via a leaf blower or compressed air. This would force burnt fuel out of the barrel. There also would have to be a check valve between the chamber and venting source, because combustion would damage venting system. The check valve would have to be modded so that it can be opened a low pressure from venting source side. Maybe even have it slightly opened then force from combustion would force back close. Then have additional spring to reset check valve.

Repeat:
Then the process will be reset. A problem is that this method you wont be able to use a combustion driven force for reloading mechanism. Also electronics will be a bitch.

This was posted so that we could point out and hopefully solve the more then overwhelming number of problems. Trust me there’s over a billion in my above process (I just got done counting).

If you have any concepts be heard! Also diagrams would be greatly appreciated. Make sure you think out before posting so that Im not here correcting mistakes. By that please don’t be shy though.

None of these 2 liner bullshit posts that ive been reading a lot…

Posted: Wed Mar 15, 2006 9:05 am
by saladtossser
if u have been checking air-power.net you would have seen this:
http://devinexecution.com/airpower2/det ... age_id=505

i have a few questions: how portable do you want it? and how many shots do you want before you take a break?

if you want it to work indefinitely, i suggest a very small single-acting pneumatic cylinder worked with a 12v emergency pump, not a co2 tank.

Posted: Wed Mar 15, 2006 10:22 am
by Rambo
Why should we make thinks so complicated?Why do you think that the combustion will damage the ventig "sistem?".It never happend to me.My new gun uses alkohol=> no fueling "sistem".The oxidizer is mix of O2 and air so no missfires or week shots.The gravity feeding works well(sometimes it fires two in the same time but what ever..) it can be replased by bolt action.The complications will only make the gun unreliable.

Posted: Wed Mar 15, 2006 2:39 pm
by CS
I think others and myself still are not sure to as how your guns works. Could you possibly go over the steps needed to shoot it and possibly list components needed? Sure you proably explained it already with some detail, but I just dont have the "motivation" if you will to dig threw your 163 post to find out.

I just cant comprehend how it works, maybe because its to simple... At any rate, what keeps the whole magzine full of ammo from rolling out? (you noted 2 sometimes will shoot, but not the whole magazine) But a blow back mechanism could be added with few more diffculties. Thanks in advance. Im looking forward to your reply.

Posted: Wed Mar 15, 2006 3:39 pm
by Rambo
To shoot with the gun first I put 20ml of metanol with a sirilyk.Then insert some balls in the magazine.I connect the house (wich I used to fill the alkohol) comming from the small bottle to the valve on the bigger bottle.I open the valve and now small stream of air is venting the chamber.I push the trigger(wich isn't on the picture) and the fuel combusts.4 seconds after that it is ready again and I push the trigger again....until it run out of air.For semi auto I roccomend O2 riched air.

Posted: Wed Mar 15, 2006 3:51 pm
by saladtossser
electronics can be simple... a motor, a cam, a few of these around it
you can control the speed of the motor, you control the rof

for loading, try clides blow forward design

this is one of those projects when the only real difficulty is money

Posted: Wed Mar 15, 2006 7:03 pm
by CS
*still confused*

Ive asked several others and none of them understand exactly how it works. Maybe a diagram or a baby step how to would be better. Im super intrested in making a gun such as this, first I need to learn how it works... lol

sirilyk=syringe?

Were do you put the methonal?

Why both methonal and alchol when there both flammable?

Although I dont have the foggiest on how it works, could propane be used for the combustible fuel?

Posted: Wed Mar 15, 2006 7:14 pm
by theregoesthewindow
I don't think he uses methonal, instead he just presses the trigger, creating the spark and igniting the fuel. Then the air from the bottle vents the chamber as the alcohol(sp) evaporatesand until there it is the right ratio to combust, again.

Rambo: That is my understanding, if I got anything wrong feel free to correct me.

Posted: Thu Mar 16, 2006 1:44 am
by Rambo
Sorry for the 'surulyk', yes it is syringe.Metanol=metil alkohol.No one should use metanol in close spase.The gasses from the burning are some kind of different(more toxic I think).I want to upload a video of my hybrid turning in to auto comb. I had a link but I coudn't upload to it.Can I have another link please.

Posted: Thu Mar 16, 2006 2:06 am
by CS
For videos you need to talk to PCGUY. Do you have AIM or MSNM?

A longer and more detailed explination would be appreicated. To tell you the truth I will more then likely end up constructing a cannon similar to yours and if I can a full size version to shoot golf balls. Hence the question if I can use propane.

Posted: Thu Mar 16, 2006 2:14 am
by Rambo
Offcoure you can use propane but it will be very hart to get the right amount of air and propane in the same time.With alkohol it is awlays the right amount.I have only skype.I'm ramborambo8569.

Posted: Thu Mar 16, 2006 3:15 am
by Brian the brain
Could't you just use a moped engine or lawnmower engine and use the excaust gasses to drive a projectile??

Posted: Thu Mar 16, 2006 3:25 am
by CS
No... Have you ever shoved a potato in a tail pipe? It seizes the engine. Rambo dont you have a diagram of how the cannon works?

Posted: Thu Mar 16, 2006 3:32 am
by Rambo
This may be usefull for a strafer.But a realy big engine is needed.I have 2.5 cubic santimetars(0.5L per second).A rocket engine may be...

Posted: Thu Mar 16, 2006 4:37 am
by CS
I think Im starting to understand how this works...

You inject fuel into chamber, then you add oxygen. You fire and then next projectile falls then you simply put more fuel and oxygen in? So what happens to the exhaust of the last combustion? When you fire in fast succesion do the shoots get weaker and weaker?

If this is so, that would mean that your ROF is limited to how fast you can inject both the oxygen and fuel? What is the ratio for oxygen? And in such a design I would assume that propane would stay at its ~4% ratio? Im thinking about cutting all other projects to start on such a cannon, so im very intrested in your response.