Longer spark isn't as hot. Shorter spark is hotter, but doesn't light as much gas on fire. Best spark would be one that fills your whole chamber, instantly superheating all the air inside, creating pressure with out the need for fuel.

I absolutely love Excel. I'm pretty sure that this graph is correct. If anyone thinks otherwise, go ahead and yell at me, I don't care. Well I do care, b/c i'll need to change it. I've attached an Excel file that will let you change the pressure to whatever you want.

http://phoenixlabs.cjb.net ...

Basically the same (innate) skills you need to design a spudgun apply very well to mechanical engineering. I believe the quality of the gun reflects how skilled an engineer the builder is. Of courese this is affected by availability of tools, cash, etc. YOu still need to have a lot more schooling to ...

Technically i don't think it's zero volume, but un undefined volume which would relate more to an infinite volume. It's like trying to find the area of a u. Because it's unbounded it has an undefined area.

Allright then. We'll see how long it works. It may actually be just fine but I tend to be on the safe side. One kid in my class, for example made a gun using unregulated CO2 from a 20 oz. tank. He's not dead yet, nor did his gun explode which just shows that it's possible to get away with being ...

Well the wood's pretty much guaranteed not to shatter, lol. 2 inches is pretty thick and considering it's hardwood it might even be overkill. HOWEVER the screws can rip straight through the pvc pipe. It's because the screws have so little of a cross section that they can act like knife blades and ...

The two 90 deg. bends should be fine. What I mean to look out for are those guns like the sniper with a lot of twists and elbows. It looks really nice, but sacrifices some in power. It's all up to what you want out of you're gun. As for the paragraph on chamber to barrel ratios this should help. It ...

Another thing that matters is barrel length, A longer barrel gives the potato more time to accelerate faster, but the length you need for a cetain speed increases exponentially due to wind resistance in the barrel. Another thing to consider is the width of the barrel. wider is generally better if ...

The front part seals REALLY well so well in fact it takes about 10 lbs. of force to jam it back manually with a stick. I suppose o-rings might help a bit, however wwith the gun charged to say... 50PSI you've got 61= (50 * (((1.25/2)^2)PI)) LBS. of force sealling that thing shut. 61 LBS! All O-rings ...

Actually it sealy perfectly. That's because it seals against the side of the coupling which come slightly tapered to ensure a good fit. I don't know if will hold air for days on end, but it works for me.

Lucky for you, I've never seen anybody that sells it around here, and that's when I checked around for a couple days for a physics project, although I was looking for 2.5 in. Maybe i'll just take a little trip to Fresno to get some

Here's my design for a piston type valve with a minimum of modification. I've got it built and it works, although not below 30 P.S.I. This could probably be remedied by improving the seal between the rear coupling and the 2 in. pipe.
!!!NOTE!!!
I built this thing around a wye which normally is only ...

Hey i had this same problem, what you wanna do is either:
1) Get a higher flowing blogun/ball valve
2) Get a paperclip and put it into the center hole (You need a little airflow through the hole, but not too much.)

Or do both.

Well you should know that it's going to be hard as hell to find pressure rated 6 inch pipe. Almost all the stuff at Lowes over 2 inches is cellular core sewer pipe, which is bad to use in almost any situation.

Hmm, ok then. Must needs find thicker pipe.

Either way you can mess up on a hybrid and be fine if you're a 1/4 mile away in a cement bunker