P5

[PCGUY]

<div align="center">P5

Provided By - Tim Jones and Das Hammer

Tim Jones - Das Hammer and I recently modified one of his pneumatic launchers for competition in a pumpkin catapult contest (Spencerville Covered Bridge Festival, October 11). Rules for the event were simple: (1) Use any means available to propel a pumpkin of any weight to a target 200 ft away from the launch point. (2) No part of the launch vehicle may extend over the firing line. (3) Each participant must launch six pumpkins for record (site-in shots are unlimited). (4) Each launch is scored by distance between the target (flag) and the pumpkin's initial point of contact with the ground. (5) The launcher with the lowest total distance of six launches is the winner. Prizes are $75 (first), $50 (second), and $25 (third).

Initially, we surveyed the local pumpkin patches to characterize the available projectiles. Our first thoughts were to fire small ornamental pumpkins in a 3" or 4" barrel. We found that few actual pumpkins were available in this size range, although gourds, acorn squash and such were available. Feeling that these projectiles would have deviated too far from the spirit of the event, we searched for the most plentiful size ranges of available pumpkins. We found vast quantities that were approximately 6" in diameter, averaging 2.7 pounds in weight. These were not deeply furrowed (almost smooth), were almost spherical to slightly elongated, and could be purchased for $0.75-$1.00 (we could never sully the name of pumpkin chucking by prospering with pilfered pumpkins). These seemed ideal for our purpose.

Having standardized our ammunition supply, we then turned to preparing the launch vehicle. The launcher we started with had plenty of air capacity (too much, as we later determined). It has two pressure chambers, each of 4" Sch 80 PVC pipe x 48" length. Each pressure chamber is connected to a 2" in-line sprinkler valve via a 2" union. These valves are modified to trigger pneumatically by a 1" Rainbird sprinkler valve, which is also modified to trigger pneumatically. The operator's trigger is a standard 1/4" blow gun on 10 ft of flexible PVC hose (300 psi rating). Elbows (2" Sch 40) from the valve outlets direct air into opposite ends of a 3" Sch 40 PVC tee. The short axis socket is adapted to 3" female NPT thread, to accept interchangeable barrels (I'll post pictures as soon as internal e-mail is back up). Launcher configuration is similar to Joel's Mega Launcher, except that the barrel is centered between and coplaner with the pressure chambers. Measurements showed that the space between the pressure chambers would just barely allow a 6" barrel and coupler.

To build the barrel, I first threaded the end of a 3" Sch 80 PVC pipe and cut off enough extra to fill a 3" socket. This nipple was glued into a 3" (soc) x 6" (spig) Sch 40 bushing, which was glued into a 6" coupler, which was glued in turn onto a 6" Sch 40 PVC pipe x 10 ft. This was too long for the launcher to fit in Hammer's truck, and was almost three times the volume of the pressure chambers. I trimmed the length to 60". This was still more volume than the chambers, but the length roughly matched the length of the chambers and valves, and modeling showed it would generate usable velocity.

Next came the artillery mount. A three pound pumpkin, accelerated to 400 ft/sec in 40 milliseconds, will generate more recoil impulse than either of us could handle. We also wanted to repeat azimuth and elevation settings as close as possible from shot to shot. After much design effort, we settled on a cradle and frame mount that mimics The Big Ten Inch, a pumpkin cannon with a 10" dia. x 110 ft long barrel. Our mount is made of 3/4" plywood and 2x4 and 4x4 lumber, joined mostly by lap joints, wood glue and screws. The cradle has a thrust block that is custom fitted to the 3" tee, and pivots on the base around a 30" piece of 1" steel pipe. The base has four sets of holes bored into the 4x4 uprights, for 30, 45, 60 and 90 degree elevation angles.

Initial fire testing used plastic 1 gallon antifreeze bottles for ammo. These are a perfect fit (just a little squeeze required) in a 6" Sch 40 barrel. When filled with water, they weigh 8-1/2 pounds. Working up from 30 psi to 95 psi, we were able to accurately place these containers 900 feet away at a launch angle of 60 degrees. Once we were sure the launcher and mount were not going to self-destruct (the mount never even shuddered), we developed our firing tables using pumpkins.

We tried cutting pumpkins with a section of sharpened barrel material for a perfect barrel fit, but this lead to problems right away. The force required to ram the cut pumpkins home with a 3" Sch 80 pipe was often enough to break the tops out of the pumpkins. These disintegrated immediately after leaving the barrel. Also, we suffered several minor injuries trying to persuade stubborn pumpkins into the barrel. This was not the way to go. We ended up using the bottom half of our 1 gallon jugs as shot cups for slightly sub-caliber ammo. This was much easier to load, and produced consistent (predictable) low friction.

Das Hammer- The device is currently dubbed the "P5" which stands for "Peckhart's Potato, Produce, and Pumpkin Persuader" or something like that. We did an 85 degree shot (almost straight up) at the contest with 75 psi. There was a little over 20 seconds of "hang time" on the 2.2 pound pumpkin. It came down hard and buried itself in the 4" deep crater that it made. It didn't explode like the others, it just firmly planted itself into the earth. The top of the pumpkin pile was actually below ground level!

Later that night, we set it down to 45 degrees and cranked her up to 95 psi with a similar sized pumpkin. Although it is not official, witnesses claim that it traveled over 1/4 mile. We won't know for sure until the beans come off of the field and we get a chance to find the points of impact. This launch also used the "piston" that Tim talked about (it was half of a one gallon container).

Another interesting variation is using "Triple Aught Gourd Buckshot". We threw about 7 of the mini pumpkins down the barrel and let fly at around 80 psi. They held a pretty tight pattern as they flew threw the tree branches and out of sight (it was getting dark).

Provided By - Tim Jones and Das Hammer</div>

[theexp]

BEAST, another awsome pumpkin gun, I Like it. Whats the furthest it can shoot? Whats the recoil like? Nice stand

[syco kilaa]

wow, imagine if you tried to shoot a bowling ball out of that thing, the effects would be devistating...

[bubblebathman]

o i say nice annon not many punkin cannons nice stand by the way and how much does it cost to build one of these

[WOW!!]

really kool , iam building one like that, right now it is a 2 4'' chambers 5', and 1 sprinkler and 1 side and a ball vavle on the other, its a beast, but, it could be better so iam going to try and get 2 10 4" pipe and put them on there, AND DAM, that thing would be powerfull i hope lol mooohahaha

Josh

[Shrimphead]

This thread is 5 months old.

[drac]

Moo

[saladtossser]

these are not real threads, these are comments to an official...

they are ment to be commented upon

[WOW!!]

This thread is 5 months old.

And?

[potatochickenboy]

seriuosly, who cares how old the "thread" is....


but still, NICE CANNON!!! me and my dad want to make one 4 halloween and shoot pumkins over our neighbors house wen their on their deck... lol

[SpudStuff]

I care ad do many others. It is quite annoying when YOU, yes you, kick up dead topics to ask a retarded question or say "cool man" or some other bull****.

[Jolly Roger]

Edit

[)DEMON(]

me and my dad want to make one 4 halloween and shoot pumkins over our neighbors house wen their on their deck... lol

That sounds fairly dangerous. You shouldn't be doing stuff like that, unless you are trying to get lawsuit. What if you get a pumpkin through a window and kill their cat? 'NOT THE CAT!!', seriously I don't think you should be doing it. I don't know how you got your dad to want to do that.

[Jolly Roger]

Edit

[gaskas]

I would like to build a Pumpkin gun to shoot 3 to 400 ft but dont know where to start
Can anyone please help me with plans or web site to get started