A few new plans

[Hero]

(i couldn't find a solid answer in the search area...sorry!)

I currently have a run of the mill spud gun that iI constructed that runs off Aqua-Net. I was wondering if i could use Ether/engine starting fluid? Some say that it works wonders, and others say that your cannon will explode. Will i be ok? My gun is built out of PVC , using PVC cement.

My other question is i'm planning on building another gun that runs on propane. I'm planning on using a 22"x4" camber (with the end caps it'll be about 3000cc). Will about a 3'x2" barrel be a good ratio for that size? Or should i go bigger? Anyone know that approx. cost on this too? just curious.

Thanx!!

[willarddaniels]

Just about anything works better than hairspray, especially considering the residue after the combustion.
You should be fine to use other propellants in this cannon.
Use a longer barrel, like 7'
Call or visit your local harware/plumbing supply for prices.

[Insomniac]

My gun is built out of PVC , using PVC cement

We can't really tell you much based on that description. Is the pvc pressure rated? Are you using pressure rated fittings? Did you prime the PVC before you glued it?

If you answered 'no' to any of those i wouldn't risk it.

[deusXmachina]

Ether is.....it's unreliable is what it is.

Yes, it does work far better than hairspray, but it has a few drawbacks (some a lot worse than others). In my experience, it's very difficult to get the fuel/air mixture just right with Ether/starter fluid, it's very "energy dense" and usually you need FAR less than Hairspray (if you're used to spraying 3-4 sec of hairspray, half a sec of ether will do). Also, it is definitely more powerful than hairspray when you get the ratio right, in fact if you get a stoichiometric mix and your PVC isn't up to the pressure rating, you could very well grenade the chamber.

In three words? Go with propane.

[splinterhelix]

I think the type of fuel should also be considered. Certain types (gasoline, acetone... off the top of my head) cause PVC to become soluble, so no matter if the PVC is pressure tested or if it's very well-built, you'll be risking a busted chamber.