If you look at a tank, about halfway down the barrel, there is an odd shaped “collar” on it. Perhaps it is on other artillery pieces as well. What is that thing?
While waiting for Tripler to respond, I think it is called a compensator. I could speculate as to what it compensates for, but I’ll wait to hear from Trip.
This bit of trivia is based soley on my teenage model building endeavors and could be TOTALLY wrong of course:)
Just a guess but I would be willing to bet that it is part of the mechanism to minimize recoil when a shell is fired. Remember the principle of “equal and opposite reaction”? With the power of those cannons you don’t want to be sending the tank in reverse evertime a shell is fired.
While I wonder why an Air Force Engineer would know, the old Tripster may surprise us. Paging Ex-Tank…
DOH!:smack:
I’m sitting here thinking “ExTank will be along shortly to give up Tha’ Dope” and I go and type Trip’s name in.
mea culpa
I think its the ‘bore evacuator’, which helps clear out fumes, and assists with balancing and recoil of the gun.
Not sure, as I’m no tanker.
According to my friend, a former Marine, it is the equivalent of a pipe coupler. It is a section with an interrupted thread that allows removing the front barrel extension so that the gun can be used in cramped quarters such as forests and narrow city streets. The barrel with the extension is so long that it would be virtually useless in such situations. Removing the barrel extension reduces range and accuracy but long range and extreme accuracy at long range isn’t needed in cities and forests.
This is possible with current tank cannons because they are smoothbore so there is no precision rifling that has to match up at the joint. The shell is fin stabilized and is propelled through the barrel by a sabot. The sabot expands under pressure, like the old-time Minie Ball, to seal the barrel and prevent blowby of the propellant gas. It has a lot of aerodynamic drag so it slows down rapidly after leaving the barrel and the shell goes on its way.
Heh? What?!? This is a new one to me. . .
IANAMBISWIW*, from what I’ve read in the past, the “blister” halfway down the barrel is in fact a bore evacuator, allowing for some of the gas pressure to do whatever it has to do to make the Army happy.
There is a laser compensator on the tip of the barrel muzzle, which detects ‘bending’ of the barrel due to heat, stress and strain, etc. This compensator feeds information to the gunnery computer and adjusts the aim point accordingly to keep it true.
But UncleBill is right. I just clean snow off of runways and dream about playing with tanks and stuff. 
Tripler
- I Am Not A Marine, But I Sometimes Wish I Were – they have cool toys.
The device in question is usually called a fume extractor. It is most definitely not a coupler. Tank main guns most emphatically do not come apart as you described, barring catastrophic failure. Your friend is either mistaken or pulling your leg.
The device in question is usually called a fume extractor. It is most definitely not a coupler. Tank main guns most emphatically do not come apart as you described, barring catastrophic failure. Your friend is either mistaken or pulling your leg.
Why most emphatically? Sounds to me like David Simmons, or his friend, might have a pretty good idea here.
Peace,
mangeorge
From this page
[sub]Emphasis mine.[/sub]
Mangeorge, I included the “most emphatically” first and foremost because it’s not the case. The Rheinmetall smoothbore on the M1A2 does not break into pieces. Doing so would seriously weaken the gun’s structural integrity, slash penetrative power, and serve no purpose. Tanks are not city fighters: the US armored forces were designed for a thrust across central Europe, not an urban meatgrinder.
Sorry, Trucido. Guess I should’ve added a “winky” there. 
Maybe in a movie, huh?
Well, he must be just plain wrong then because he’s a serious guy who as far as I know has never told a funny story in his life. He even went and got some pictures of him with his cannon. He was a loader.
My faith in humanity, heretofore so high it was out of sight, has been smashed.
Well, he must be just plain wrong then because he’s a serious guy who as far as I know has never told a funny story in his life. He even went and got some pictures of him with his cannon. He was a loader.
My faith in humanity, heretofore so high it was out of sight, has been smashed.
He probably wasn’t wrong. Some cannons are constructed with multi-piece barrels. A version of the famous German 88mm Flak gun was designed with a three piece barrel (chamber section, center section and muzzle section) for easier maintenance and manufacture. (Souce: German Artillery of World War Two by Ian V. Hogg)
No doubt other artillery pieces had similar design.