SpudFiles

USG was asked to build a cannon to chuck 2 x 4's 200mph this past Tuesday for National Geographic channel show being filmed today (Saturday). The show is called Rocketville Science and the episode relates to wind driven (tornado) debris. Even with what seemed to be a ridiculous time frame we accepted the task and this what we overnighted (UPS bill was crazy) Thursday (8:30am HST) for Friday delivery. We actually only shipped the valve, pilot and some brackets. The valve by itself weighed a touch over 110lbs!

According to HGGT it predicts a 13.5lb 2X4x10' with working pressure of 125psi to exit at 292fps. Max trajectory shows 2200+ ft?

Specs:
6" schedule 80 Tee housing
5.75" piston diameter
5" sealing diameter
piloted with modified 2" sprinkler valve
Chamber is 10' of schedule 80 6"
Barrel is 20' of schedule 40 4"
3/4" steel end plates (sand blasted and parkerized) secured with 5/8" threaded rod.

The photos here represent a shortened version of the above to verify it working. We did clock a softball at 711mph with a 10 barrel while the cannon dragged itself, the steel sawhorse and operator back 24". First time I really felt the need to wear a cup and welding helmet while firing.

Sadly no video, and few photos. This was 40 hour build in 2 days, 10 pots of coffee, and a couple of angry CNC lathe / mills. Thanks USGF.

USGF has photos of the piston.

jagerbond wrote: Sadly no video, and few photos.

I'm sure national geographic will eventually oblige a 2x4 at any velocity is a formidable projectile, this should be a sight to behold! Are they going to use a rectangual cs barrel or a round one with a sabot?

we sent uhmw pucks .01 smaller than bore diameter for attaching to the 2x4.[/GVideo]

That is good size for PVC. I hope it holds up OK. I would have guessed they would have used one of Martin Engineering's solutions. Nice job landing the project.
http://www.martin-eng.com/node/425

This is larger than Martin's valves which have a 4 inch discharge.

Nice... did they specify a pneumatic or is there another reason you didn't send over one of your stock combustions with a larger barrel?

May I ask what is used for the bumper? This will need to be up to the task at hand.

Gents,

Here is the picture of the (caffeine) crazed builder with the piston in question.

USGF

LOL @ Mike + caffeine!

Yes, I definitely hope you have your bumper sorted out!

Bumper is 1" open cell foam and has worked before in other builds. The rear part is 2" UHMW and should take some abuse. Shooting commenced today, no phone calls from the production crew as of yet.

Tech - the schedule 80 is rated to 280psi working pressure. Most of the failures I've experience occur at the joints. The steel plates and threaded rod should keep the 2 tons of force contained well.

JSR - we decided to go the pneumatic route so they could have greater flexibilty and smaller size. Combustion cannon required to make that speed would be bigger. Also, they wanted to use a common air compressor for fill.

Thanks for the info and the great piston photo. That is a nice close ratio piston (OD to seat ratio is near 1:1). That should pop open with a real bang.

jackssmirkingrevenge wrote:

jagerbond wrote: Sadly no video, and few photos.

I'm sure national geographic will eventually oblige a 2x4 at any velocity is a formidable projectile, this should be a sight to behold! Are they going to use a rectangual cs barrel or a round one with a sabot?

I forgot to add 16,000+ ft*lbs of energy!

Wow... I'm impressed by my own cannon which uses the same sprinkler valve as its main valve... yours is piloted by one. I can't imagine what it's like to watch that thing fire.

About the max energy my 2 inch valve will do is about 1800. Wow that is almost a full order of magnitude larger. Nice job. No wonder the launch had such a large recoil.

No phone calls - either they're extremely happy with it and have forgotten to call in their enthusiasm, or most of the production crew have been impaled by a freak 2 x 4 skewer

jagerbond wrote:I forgot to add 16,000+ ft*lbs of energy!

That's well over what even the heaviest loading of 0.50 BMG can generate, impressive! Though somehow I don't see this replacing the Barrett on the modern battlefield....

Also, it's amazing to have a business that is the first one someone calls when they need to fire a plank of wood with more muzzle energy than an anti material rifle. I'm clearly not living my dreams, but I'm working on it

So what are you naming the valve? The tornado similation is how the Suprha valve came about, I think it was in that order...