DWV? Does it come in a diameter that will accommodate a football?
The cans were free, why would I buy plastic pipe?
Plus if it fails it tends to fail safely at the duct tape seams, and you can always experiment with combustion chamber and barrel length. It's easy to replace dented sections too.
Posted: Sun Apr 18, 2010 8:17 am
by Duct Tape
... oh and it takes 15 mins to make, if you're quick, but earplugs would have been a good idea.
Posted: Sun Apr 18, 2010 8:54 am
by Crna Legija
lol 45 seconds of gas sounds like way to much
Posted: Sun Apr 18, 2010 9:22 am
by POLAND_SPUD
The cans were free. I already had the propane blow torch
well yeah but these things do cost...
If you really want to save a lot switch to threaded metal fittings & pipes...
They are wayyyy stronger than PVC and can be reused... not to mention that it only takes a couple of minutes to assemble a complete gun from parts
Posted: Sun Apr 18, 2010 10:19 am
by Duct Tape
45 seconds may sound like too much gas, but it isn't.
We tested it from 10 seconds through to 80 seconds.
60 was the most powerful, but it kept popping seems and blowing the back out, which meant replacing the bottom can. 45 was still powerful, but didn't wreck the cannon, plus we could still hear afterwards!
Posted: Sun Apr 18, 2010 11:43 am
by MRR
This might be in the same price region, without the fancy stuff (pistol grip).
Any low-ball quote of a cost is pretty silly. I've got guns that were "free" since all the parts were left over from other things or just scrounged from the garage. For example;
And I'm a bit suspicious of the 200 feet claim. For an unstabilized football?
Posted: Sun Apr 18, 2010 12:16 pm
by jackssmirkingrevenge
jimmy101 wrote:Any low-ball quote of a cost is pretty silly. I've got guns that were "free" since all the parts were left over from other things or just scrounged from the garage.
I'm pretty sure that it's not an over estimate. Here are some figures...
We fired our best vertical shot with a flight time of 6.5 seconds (This almost blew the base plate right out of the bottom can). Ignoring air resistance (I know ) this would give an exit speed of around 32 m/s, and a maximum height of 52 m. At 45 degrees this would give a range of 104 m or 341 feet, so a claim of 200 feet is actually quite reasonable. I would guess that air resistance reduces the range somewhat.
Even if you just take the shots we filmed for YouTube you'll see we have 5 seconds of flight time at about 75 degrees, equating to an exit speed of about 26 m/s. This would give a range of 69 m or 226 feet at 45 degrees.
You can use the equations of motion to verify my figures or just use this projectile motion simulator.
