SpudFiles

jackssmirkingrevenge wrote:

High-PSI wrote:Honestly, though the recoil is high, it is soft. It is hard to describe. Basically, there is alot of rearward travel of the cannon when fired, but it is not a sharp blow to the shoulder like a 12 guage shotgun would be, kind of like the difference between being hit in the shoulder with a slow moving sledge hammer versus a fast moving fist.

It's down to the relatively low acceleration compared to a 12 bore, the same reason why pneumatics were used to fire dynamite until desensetised explosives were developed to enable them to be fired from powder burning artillery.

Oh, one quick question, (and I know this is a vague description), at 210 psi, it had a bit of kick. However, at 230 psi the recoil felt like the pressure was far more than a mere 10% higher. It is almost like the recoil energy increase is exponential, not linear as the pressure rises.

Knowing the weight and velocity of your projectile, and the weight of your launcher, you can calculate the recoil energy. In this case, you should also add the mass of air in the chamber to the mass of the projectile, as it makes a significant difference.

Technically, recoil energy should be roughly proportional to pressure, I would put the perceived exponential increase down to your impression - though it would be interesting to mount the launcher on a free-moving trolley and quantify the results.

Thanks.

It is a funny thing, there is plenty of recoil that really throws you backward. But, it is not painful in any way. I think I could take about twice the recoil it has now before it hurts. I am not sure I could stay on my feet, though.

The increase in recoil me, indeed, be my personal impression and nothing else. That is possible.

Matt

As suggested, you could try and quantify the recoil by mounting it on some kind of wheeled or sliding trolley and measuring the amount of rearward travel. The important thing is that friction and projectile weight are consistent, all you'd need to do is fire a couple of shots at various pressures.

Here is another angle of that same shot. You get a much better feel for the power in this video.



Matt

Hey Guys,

Tomorrow morning (July 9th) we are taking the cannon out for some serious destruction. I am picking up some cinder blocks in the morning to blow apart. I promise damage pics and videos.

You haven't lived until you have seen a cinder block explode on impact!



Matt

That sounds awesome! Do you by chance have access to a high speed camera?

That thing is a very serious cannon. Damn thats nice.

Gun Freak wrote:That sounds awesome! Do you by chance have access to a high speed camera?

Nope, no high speed camera, I am afraid.

I will get what video I can, though.

Matt

Some youtube links.







I setup cinder blocks for testing. These are 4 inch thick SOLID cinder blocks, not the cheap hollow blocks. One video is of a golf ball, wrapped in duct tape, shattering one of these 4 inch thick blocks. All other shots were with 2 inch compound rounds.

Enjoy.

Matt

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Impressive!

How come you didn't use the muzzle brake?

Also, bit late now but always beware ricochets when shooting at hard stuff! At worst at least shoot at an angle where if something comes back, it won't be in the direction of your loved ones.

I did testing with and without the brake. These videos happen to be without the brake.

We were worried about recochets on the first shot. After that, we knew all the rounds went clear through the blocks and nothing came back at us. The golf ball was another matter, though.

Matt

Last time I shot rocks with golf balls the golf ball fell to the floor and didn't ricochet for some reason. It just fell to the ground like a rag. What condition was the golf ball in after you shot the block?
I think shooting a more sturdy surface might have reduced ricochet actually. If the golf ball hits hard enough to bust it apart, it won't ricochet.
One time, I shot a bunch of steel BB's at a wooden board, and they all flew back and nailed the guy standing next to me. They had really low energy coming back and didn't hurt him, but I still felt bad about it. Accidents happen, so shield everyone nearby.

Good point.

The golf ball was cracked in numerous places, but did not break apart. I think that was, in part, from the cinder block absorbing the impact and, to a small degree, the thick layer of duct tape adding a tiny bit of padding to the ball.

Speaking of ricochets, I would love to fire a 2 inch tennis ball at a sheet of plywood. I bet it would punch right through. But, if it doesn't, that thing will really rebound!

Matt

I figured I would update my thread with some detailed information and pictures of the cannon at this point.

The tank and shoulder stock are steel. They were powder coated black. The barrel, machined barrel clamps, grip, and rail are aluminum. I had them anodized black. I updated the pilot tube from the original copper item to a braided stainless tube for looks and durability.

Also, I hydro tested the tank to 625 psi. So, I know it is safe. I will be firing the cannon at 400 psi this year (possibly up to 500 psi if my should can take the kick). GGDT shows 3,000 ft pounds of power at 500 psi. So, I am not sure I want to hang onto it at that pressure!

Anyway, my compressor is taking up much of my time now. But, I wanted to show you guys the pictures and give an update on this while I had a few minutes.

Matt

:notworthy: :hello1:

Beautiful!!
I had missed this earlier due to a break from spudding but wow!

I have a similar sized valve on my large 3" barreled cannon.
Maybe I should go with a smaller diameter bore..

Looks absolutely great!