SpudFiles

Hi, totaly new to the scene, and I am bad at introductions. So... with that all said and done; what are some efficient ignition systems for the average noob?

After having built my first combustion cannon (instructions taken from the Backyard Ballistics book), and making a few changes (using a piezo instead of a flint sparker), I have noticed that the cannon is rather inconsistent in it's performance (more often than not, it doesn't fire). For fuel I have been using Axe body spray (it smells just as bad if not worse after combustion IMO) with or without a small amount of Greengas. The most distance I have been able to get out of it is around seventy feet.

I know the fuel to air stiochometry plays a huge role, and that you guys call this type of a cannon "spray 'n pray", however, it would seem to me that if i could pump more current through the spark gap, I could vastly improve it's reliability. I am pretty handy with electronics, and wouldn't mind building a Flyback driver circuit (that would also be a significant voltage boost, so a a double plus). Would it be worth the trouble though, or should I just move on from this type of combustion cannon and go for more advanced projects.

Oh and my first day of using the cannon I lost an eyebrow while making adjustments to the sparkgap.

per0xide wrote:Oh and my first day of using the cannon I lost an eyebrow while making adjustments to the sparkgap.

hehe, I can relate to that.

For an ignition source, try a stun gun if they're not illegal where you are. They're relatively cheap and provide a constant high voltage ignition source. Unfortunately for me, they are illegal in Australia so I can't tell you specifics about them, but electronic grill ignitors apparently are a good alternative.

Hope this helps in some small way.

Always look at your fuel metering before anything else. If you're adding unmetered propane (green gas) then you are likely making a rich firing environment as propane is much more pure than deoderants etc.

More current will likely not improve reliability UNLESS you have enough current that it will damage electrodes/make plasma.

For more reliability ignition wise a spark strip, which places multiple sparks along the length of the chamber is a good choice. If you need any help, let us know.

For ignition choices you could try a stungun, flyback generator, flux capacitor, camera flash circuit (with an ignition coil preferably), tesla coil, marx generator.. The world is your oyster.

A spark is a spark is a spark...a higher current one isn't going to make any difference in the power provided by a fuel air mixture. Multiple spark gaps can maybe make some difference if they are placed properly in the chamber...that being in the center and equally spaced down the length.

Take a look at the spark strip in the Trip Thunders. I wouldn't call it a perfect strip solution but it is very reliable. Also too, if you haven't already, go to Burnt Latke's site and read it carefully. It is considered the defacto goto for all things advanced combustion cannon.

Welcome to Spudfiles! and keep those eyebrows on next time....

^.^ im just wondering if you chose that name PERoxide for a combustion use? u could try acetone peroxide t,a,t,p (educational use) take the , out
i put it in just because you never know but anyways search up on if you want and then you could use a sparker? or a shock. or whack O.o

I have no clue what to say to your post airhead.

Use tatp in PVC? You must be stupid, right? It's things like that that create moves to get the hobby banned.

Incase you didn't realize, ignore airhead's post.

starman wrote:A spark is a spark is a spark...a higher current one isn't going to make any difference in the power provided by a fuel air mixture. Multiple spark gaps can maybe make some difference if they are placed properly in the chamber...that being in the center and equally spaced down the length.

Take a look at the spark strip in the Trip Thunders. I wouldn't call it a perfect strip solution but it is very reliable. Also too, if you haven't already, go to Burnt Latke's site and read it carefully. It is considered the defacto goto for all things advanced combustion cannon.

Welcome to Spudfiles! and keep those eyebrows on next time....

The higher amperage would make the spark hotter, allowing for a more reliable fuel ignition, since there would be increased heat. I know that it would not increase the power, I thought that it may just get hot enough to ignite the mixture when it is less than optimal.

Looks like metering is the way to go though.

*sigh* Time to get more pipe.

per0xide wrote: The higher amperage would make the spark hotter, allowing for a more reliable fuel ignition, since there would be increased heat. I know that it would not increase the power, I thought that it may just get hot enough to ignite the mixture when it is less than optimal.

Nope. The spark only passes through a few molecules, and if those molecules aren't in the right number, it won't ignite. Not enough actual energy is released to start the reaction in nearby molecules.

If a high current spark will work, then a low current one will work too. (Unless you're generating plasma or eroding your electrodes due to very high energy levels.)

A syringe is a cheap, easy, and extremely acurate way to measure fuel. You might consider that instead of a meter.
See the wiki page on fuel meters
or
here.

The propane ignition energy in terms of electrical current is quite low. As me and Bio have stated, more current or voltage will not improve ignition unless you generate plasma.

A better option is to create a sparkstrip or use a longer spark gap (which will require more power of course)

A chamber fan would help. They mix the fuel/air and increase power a bit.

airheadnoob wrote:^.^ im just wondering if you chose that name PERoxide for a combustion use? u could try acetone peroxide t,a,t,p (educational use) take the , out
i put it in just because you never know but anyways search up on if you want and then you could use a sparker? or a shock. or whack O.o

EDIT Oops, I saw Peroxide and assumed Hydrogen Peroxide as an oxidizer. The other stuff. Don't ask me.. no clue.

If wikipedia is correct. this would be against forum rules and quite a fast trip to an early grave.

I was away for the weekend. Check the concentration. If you are talkin the stuff from the pharmacy, it's pretty useless for that. The industrial strength stuff is a hasmat item. Consumer grade is 3%. Translation.. 97% diluted with water.

Technician1002 wrote:

airheadnoob wrote:^.^ im just wondering if you chose that name PERoxide for a combustion use? u could try acetone peroxide t,a,t,p (educational use) take the , out
i put it in just because you never know but anyways search up on if you want and then you could use a sparker? or a shock. or whack O.o

EDIT Oops, I saw Peroxide and assumed Hydrogen Peroxide as an oxidizer. The other stuff. Don't ask me.. no clue.

If wikipedia is correct. this would be against forum rules and quite a fast trip to an early grave.

I was away for the weekend. Check the concentration. If you are talkin the stuff from the pharmacy, it's pretty useless for that. The industrial strength stuff is a hasmat item. Consumer grade is 3%. Translation.. 97% diluted with water.

He's not talking about using peroxide as an oxidizer. He's being an idiot and implying that he should use a high explosive in PVC pipe. (T.A.T.P.)

Coming from somebody who plays with flash a lot (and fine enough to be considered a primary HE) I can say it's a bad idea. Even permanganate flashes uncontained could easily mess you up.

But when you give it a large mass of brittle material and contain it, then expect to die.

rcman50166 wrote:http://www.spudfiles.com/forums/sparker ... 13030.html

I just browsed your page and Capacitive Discharge Ignition is missing from your page. A camera flash to charge a capacitor to about 300 volts which is then discharged into the primary of an ignition coil works wonders. It may be worth the time to edit the page to add CDI. It is easy to build.