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Calculating recoil energies.

A place to ask general spud cannon related questions.
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Unread postAuthor: mark.f » Thu Nov 01, 2007 5:50 am

For all those who say this is pointless, a common college lab is to measure muzzle velocity of some sort of cannon, (I've seen it with little tennis ball guns made of cans up to pneumatic solenoid-valve based launchers), by measuring the acceleration of the recoil. I'm sure a quick search of Google-Scholar or Google-Government can turn up a few of these labs.

And Ragnarok, we don't usually post criticism based on post count, but sometimes improper wording or other erroneous information just sends some people over the edge.

I'll try to make a "lab" for measuring muzzle velocity by measuring recoil acceleration during school today, (prob. in Drafting or some other class).

Say hi to Joanna from all of us.
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Unread postAuthor: Ragnarok » Thu Nov 01, 2007 8:05 am

spudgunnerwryyyyy wrote:That is amazing, but kind of pointless for standard spudding uses. You could however make a fully auto recoil based system with this math.

It's not quite completely pointless. I know that the launcher I have kicks quite impressively already, so it was worth thinking before firing anything much heavier again.

And, coincidentally, I have a mostly complete set of plans for an all mechanical (except for the ignition system of course) full auto combustion BBMG that should be good for at least 120 rpm, and hopefully up to 300 rpm. To work reliably, it will need a couple of machined parts (both lathing and milling), so it's going to have to wait a little bit before it sees the light of day though.

@Jackssmirkingrevenge: Well, I know it's a long time, but somehow I don't know where any of it went.

Firing a 1.4 kg steel ball... where do you find stuff like that?
As for my 300g bit of 20mm steel rod, that off-cut accidentally turned up in my pocket after the engineering workshop - and the fact I had my digital callipers on me to measure it would fit my barrel is a complete coincidence (No, really, that 2nd bit is true)

@Markfh11q: I wasn't expecting criticism by any means, but I didn't want to get posts from people who don't know how long I've been doing this, congratulating me for being a well informed newbie.
However, I'm a little better known than I expected.

...And I've just noticed the broken link in my last post.
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 01, 2007 8:51 am

Firing a 1.4 kg steel ball... where do you find stuff like that?


A bloke at work handed it to me once it transpired I'm into homemade launchers. 2.75" in diameter, I'm told it was once part of a crane's ballrace. Makes 0.177 BBs look like gnat's knackers :D

Image

I still have to make a pneumatic that will fire it, but if it recoils like that just barely leaving the barrel from the combustion, I don't want to image what will happen if it leaves the muzzle at a fair rate of knots.
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Unread postAuthor: Hotwired » Thu Nov 01, 2007 10:16 am

Bring on the steel pipe launcher butted up against a sack of sand :)
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Unread postAuthor: Ragnarok » Thu Nov 01, 2007 11:01 am

I'm lucky I don't have one of those, because I cause quite enough problems with only 3/4" ball bearings.

The problem may have been that your launcher was relatively light weight compared to the ammo. Firing anything that has over a tenth of the launcher's mass could be problematic.

EDIT: Launcher topic now up: http://www.spudfiles.com/forums/viewtop ... tml#130046
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Unread postAuthor: ALIHISGREAT » Thu Nov 01, 2007 12:44 pm

jackssmirkingrevenge wrote:

Image



imagine 2.75" bb buckshot :twisted: it could work in a pumkin chuckin' cannon :?:
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 01, 2007 1:14 pm

ALIHISGREAT wrote:imagine 2.75" bb buckshot :twisted: it could work in a pumkin chuckin' cannon :?:


scroll to the bottom of this thread :D

From what I can tell, a single round holds 1,100 tungsten balls 1cm in diameter :shock:
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Unread postAuthor: ALIHISGREAT » Thu Nov 01, 2007 1:48 pm

scroll to the bottom of this thread :D

From what I can tell, a single round holds 1,100 tungsten balls 1cm in diameter :shock:


that is awesome :twisted: i wouldn't like to have that pointed at me![/quote]
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Unread postAuthor: Ragnarok » Thu Nov 01, 2007 3:14 pm

jackssmirkingrevenge wrote:From what I can tell, a single round holds 1,100 tungsten balls 1cm in diameter

That's just damn evil, but it could be useful in a zombie apocalypse.
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Unread postAuthor: DYI » Thu Nov 01, 2007 4:26 pm

All of my handheld cannons have been fairly low powered. When I used to use my 2" bore burst disk cannon at low pressure, with 1 pound slugs and no support, the recoil for the ~25 pound cannon was enormous, over 12". It is now supported by a 50 pound stand, and is in the process of being refitted for use at up to 500 psi.

I don't think that you will be able to generate dangerous levels of recoil with the HEAL, as long as it is properly supported. You may want to add some padding to the stock though. Most of the horror stories involving recoil forces are to do with PVC launchers using heavy projectiles and breaking under the stress.
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Unread postAuthor: Ragnarok » Thu Nov 01, 2007 5:25 pm

It's unlikely that I could generate dangerous recoil, but it's always best to be sure, and well prepared.

I have tried a padded stock before, but it didn't help, so I removed it because it wasn't the most attractive of things.
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Unread postAuthor: clide » Thu Nov 01, 2007 9:51 pm

markfh11q wrote:For all those who say this is pointless, a common college lab is to measure muzzle velocity of some sort of cannon, (I've seen it with little tennis ball guns made of cans up to pneumatic solenoid-valve based launchers), by measuring the acceleration of the recoil.

I am doing just that for a measurements class, but with an actual gun. Our accelerometers peak out at a few Gs (3 or 5, can't remember), so I doubt we will be able to actually back out muzzle velocity. I may try to get one of my launchers in there too.

Good to see you around these parts Ragnarok, and thanks for the informative post.

My horseshoe launcher kicked about like a shotgun and my homemade pad attempts were pretty worthless. Luckily someone suggested an actual shotgun recoil pad and it worked wonders. I would definitely suggest it for anybody considering a high recoil hand held launcher.
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Unread postAuthor: Novacastrian » Fri Nov 02, 2007 3:15 am

Ragnarok wrote:
jackssmirkingrevenge wrote:From what I can tell, a single round holds 1,100 tungsten balls 1cm in diameter

That's just damn evil, but it could be useful in a zombie apocalypse.


Maybe, if they were made out of gold or garlic? :lol: :lol:
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