need tips on perfecting cannon and ignition system(pictures)

inonickname · Sun Jul 19, 2009 3:07 am

If you overload it with fuel, it won't fire. Hydrocarbons near propane and butane (which is basically what you would be using) Have a very narrow combustive range- over 9% and the cannon won't fire, with around 4.7% being the most powerful.

However, hydrogen has a range of 4-75%, which is massive, and basically only exceeded by acetylene.

Cellcore is just fine. When it fails, it tears. (it wont fail in this application unless you drop it regularly, leave it in the sun etc). You would get a first degree burn, but it does not form shrapnel like PVC.

Cellcore is safe enough..hell you'll probably have tech post a picture of his cellcore pneumatic which is regularly tested to 100 psi.

johnrodgers · Sun Jul 19, 2009 1:36 pm

thanks for the info my friend, but i must ask do you think re enforcing it with packing mesh tape or anything else would serve a purpose in the case of a failure?

jimmy101 · Sun Jul 19, 2009 3:31 pm

theBOOM wrote:Well.. Fueled meter in abs pipe... is doable but I wouldnt want my gun blowing up.. well in the case for abs.. tearing up...

Do a bit more reading. A "spray-n-pray" fueled gun can reach the same peak pressures as a metered gun. The difference is that the metered gun will hit about the same pressure every shot. The spray-n-pray will only hit that pressure occasionally, everytime you get lucky and get the right amount of fuel.

c11man · Sun Jul 19, 2009 3:47 pm

jimmy, these pressures are from metered propane and just praying propane right? because hairspray is just not that good

Technician1002 · Sun Jul 19, 2009 4:41 pm

inonickname wrote: Cellcore is safe enough..hell you'll probably have tech post a picture of his cellcore pneumatic which is regularly tested to 100 psi.

I heard my name..

Anyway, link;
http://www.spudfiles.com/forums/abs-cel ... 17968.html

These guys did some ABS testing to the extreme. I do NOT recommend using oxygen from a welding torch to increase power. It is very dangerous.

[youtube][/youtube]

jimmy101 · Sun Jul 19, 2009 4:52 pm

c11man wrote:jimmy, these pressures are from metered propane and just praying propane right? because hairspray is just not that good

Nope, hair spray will behave exactly the same as propane or butane. You just need to get the mixture right.

The only significant problems with hair spray is it'll gum up your sparker and the possibility that it contains something like ethanol and a laquer. Ethanol is just as good a fuel as propane but it is even trickier to get the mixture right. For consitency you have to give the alcohol time to evaporate in the chamber, which it always will, eventually, if the fuel ratio is correct.

Hairspray usually also contains something like a laquer. Laquer will burn about as well as anything else if it is an aerosol. However, it behaves the opposite of ethanol in terms of needing to evaporate fully. The laquer will tend to settle out on the chamber walls. Shoot soon after fueling and the ethanol is a poor fuel because it is droplets and the laquer is an OK fuel because it is still an aerosol. Wait a bit and the ethanol will evaporate and the laquer will settle out. It's all a question of measureing the correct amount of fuel then waiting long enough for the fuel to settle into it's normal state at 1 ATM pressure and normal temperature.

Once the fuel has equilibrated the energy content will be essentaly identical to propane or butane. Of course, you still have the problem of accurately measuring how much fuel you are putting in from the spray can. That's the same problem you have with any aerosol can, even something like starter fluid which doesn't contain any liquids, laquers or solids.