Is There A Technical Definition Of Tank Gun "Jump"?

I'm wondering if this phenomenon has a precise definition anywhere. As far as I can tell "jump" is equivalent to "kick" with small arms, i.e. it is the involuntary lateral movement, both vertically and horizontally, of the barrel (as measured at the muzzle end) that is induced by the recoil process.

Also is there a rule of thumb anywhere for estimating the degree of accuracy error induced by jump? i.e. if the gun deflects "x" mils then the shell will land "y" inches from the aiming point at "z" distance, given a particular shell velocity. Or even more simple, should jump generally be confined within a certain parameter, e.g. 3 mils?

 

The guns are tested by the manufacturer with the oversight of the branch purchasing the guns. The response of the barrel to the explosion at the near end and the passage of the shell through the barrel has to be predictable so that corrections to the aim can be made. Those data points are part of the calculations needed to lay the guns properly to achieve the goal of knocking the snot out of the other guy.

Technical stuff: The Importance Of Circular Error Probable In Weaponry _ 2024

 

My boat team did time at Aberdeen Proving Grounds while our boats were getting fitted out. The track toads loved to babble-on in the chow halls.

"Dude, is any of that in English?"

"Beats me, it's just my job five days a week."

That place was screwy enough. They fitted our boats out. Put them on a freighter. And sent them to Charleston South Carolina to mate up with their crews. The crews were at Aberdeen to mate up with the boats. Left hand wasn't talking to right hand. Not at all surprised.

We ended up proceeding to our advanced base to secure it and get acclimatized. (100F really doesn't need that, of course. Right? Right.)

/ramble

 

Thanks gents, plenty to get into there.

 

Don it’s also to do with temperature and barrel wear and pressure , hence modern tanks are bore-sighted every day and they have a referencing device to keep the gun true again due to the type of round fired.
But the gun recoil should take up any kicks .
Ossie

 

Thank Ossie,

I've been looking at some research reports on gun jump, and there is a distinction between "apparent jump" and "true jump", but no definition of what these actually are!

 

True jump, at least on the ordnance I've played with, was the "book numbers" while "apparent jump" was "where the hell did the last round land?" Correct that shit." Second was more seat-of-the-pants.

Caveat: It's been a half century since I played with large bores. I wasn't gun captain then, just a guy suggesting things based on a heavily penciled map.

 

From the British trials, my tentative understanding is that "apparent jump" is the total deflection at the muzzle end, while "true jump" is the deflection at the muzzle end at the moment the shell leaves the barrel. i.e. not all of the deflection affects the flight of the projectile.

Needs confirmation, though.

 

Sounds valid, Don. If the barrel isn't dead bore straight then that angle need to be added to the true jump.

Good gun discipline comes when the barrel wobble ceases completely before the next round is fired. "Oh, shit, Oh shit, Oh shit!" trumps that rule, of course. So does "Load beehive!"