Two newbie ques please help me out

[Sabaku]

I'm currently building my first potato gun. And Ive come across two issues one is combustion chamber to barrel length. Now the specs I'm building off of day 24" 4 inch diameter for combustion and to use a 48" barrel now that ratio I'm assuming is a 1:1 ration. Now I've been reading to use 1:1.5 ratio. So I was thinking to go 18" on combustion chamber and 45" on barrel which one would give me the most power? Also I'm having some issues picking out an ignitor some people say you a lantern flint and other say go BBQ. Now I was interested in going BBQ and doing dual ignition. But I can't seem to find instructions on how to build a dual ignition. Any help you guys could offer would be greatly appreciated.

[inonickname]

Welcome to spudfiles

Stungun ignition: http://www.burntlatke.com/stun.html

Increased sparkgap w/o extra chamber holes: http://www.burntlatke.com/short.html

Spark Strip: http://www.burntlatke.com/strip.html

Piezo/BBQ ignitor guide: http://neospud.com/piezo.html

For fueling the beast: http://www.burntlatke.com/calc.html

And launch demonstrations, could help with your c:b issues: http://www.burntlatke.com/launch.html

[Combustion Monkey]

The above links cover almost everything i was going to say. I took the Burnt Latke style strip and made it wrap around the interior of my chamber for use on a coax gun. Its easy to build out of scrap pvc and bits of wire, also makes the chamber very easy to clean. I have tested it against the dual protruding electrode setup and in my testing it seems to give a better ignition, but that may just be me.