Page 1 of 1

Amazed at performance of my new potato gun. Read this.

Posted: Sun Jul 09, 2006 12:13 pm
by Johnny Blast
My new gun has a cylinder (pvc of course) 2 feet long and 4 inches in diameter for the combustion chamber. I have a 2 inch diameter barrell that is six feet long. Total length probably 8.5 feet.

Remember wiffle balls with holes made of light weight plastic? If you put a spin on them when you threw them they would curve easily.

Now: I've shot some potatoes which spun so fast that they actually curved like a wiffle ball when shot straight up into the air. The height was unbelievable. It was scary regarding how much height was reached. I used Suave hairspray which is fantastic and a lantern lighter igniter.

Have a great day people. Just a story for you.

Posted: Sun Jul 09, 2006 12:30 pm
by WOW!!
Have any pics of it??

Posted: Sun Jul 09, 2006 12:38 pm
by Johnny Blast
I don't have any pictures yet. I don't think I'll be using the gun too much because of the saftey issue: "Where is it going to land"?

Posted: Sun Jul 09, 2006 1:00 pm
by benstern
Preformance can not be it's best unless you use metered propane and a spark strip.

Posted: Sun Jul 09, 2006 1:03 pm
by SpudStuff
im sure there are instances where by chance you can get the exact amount of fuel with arosol

Posted: Sun Jul 09, 2006 1:09 pm
by huse_spud
Johnny Blast wrote:I don't have any pictures yet. I don't think I'll be using the gun too much because of the saftey issue: "Where is it going to land"?
this sounds like your first or second spudgun, trust me, the explosiveness of combustions makes them seem pretty powerful, but yours prolly isn't that good compared to people who have been doing this for awhile. i was impressed with my first combustion cannon too because i had never been exposed to any other types of spud guns.

that was a little more than 4 months ago and ive built far better cannons since then. (pnuematics)

Posted: Sun Jul 09, 2006 3:18 pm
by boilingleadbath
To be kind, I went and plugged some data into EVBEC:

You have a ~300 cubic inch chamber, and a ~230 cubic inch barrel, for a 1.33:1 C:B ratio.

If you where using metered propane and a chamber fan, you would be getting ~450 fps with a potato. As is, without a chamber fan, you are getting maybe 350 fps on average, and that number is dropped farther (on average) by using a hand-metered fuel.

Posted: Sun Jul 09, 2006 5:49 pm
by Johnny Blast
--------------------------------------------------------------------------------
To be kind, I went and plugged some data into EVBEC:

You have a ~300 cubic inch chamber, and a ~230 cubic inch barrel, for a 1.33:1 C:B ratio.

If you where using metered propane and a chamber fan, you would be getting ~450 fps with a potato. As is, without a chamber fan, you are getting maybe 350 fps on average, and that number is dropped farther (on average) by using a hand-metered fuel.

You are very kind. And yes this is only my second gun I have made, to answer a previous post. You guys are good and I had no idea that it's possible to delve into this subject so scientifically and in such detail.

Posted: Sun Jul 09, 2006 8:23 pm
by Mihlrad
all in good physics and chemistry, i hate both subjects but they help... Get some pictures up i still wanna see it.