Why does barrel length affect reload time?

[wolfstanbjord]

I am having a hard time grasping the reasoning behind why barrel length would have such a large effect on reload time, especially on secondaries. I can understand if its somehow related to the weight of the longer barrel taking more time to elevate?

It just seems a little off in my brain, would there not be stronger mechanisms to account for the heavier barrels without that much change in speed? If they were loaded from the muzzle fine I can understand it taking more time with longer barrels but these are breach loaded with presumably no to little change in charge rate.

I am unfamiliar with the operations of large bore guns at this size so please excuse me if this was a dumb question.

[AdmiralTigerclaw]

Longer barrel is in fact, heavier, yes. There are several knock-on effects.

1: Heavier barrel needs bigger, more powerful elevation machinery, to be stuffed into your turret. Stuffing more things into the turret means less room to move properly for the loading crew. Slowing them down slightly.
2: Longer heavier barrel is a longer, heavier tube that is more susceptible to storing momentum and flexing if it moves fast. Too much flex and you deform the tube, and your gun is now a worthless lump of metal a few dozen tons heavy.* So it must move proportionally slower to prevent damage in the event of flexing.
3: Longer barrel means more tube that needs to have gas evacuated, and time to cool. How much, I don't know. But you don't want to open the breech into the turret and get a lung full of freshly ignited high TNT combustion product (smoke), and you don't want to deform your gun from overheating it... see point 2.





*At the scales of battleships, all your metals and steels are actually quite flexible and/or brittle. War machines of this nature were are always operating at the very fringe of material science and represent, in most cases, the very edge of what you can MAKE them do.

[wolfstanbjord]

@AdmiralTigerclaw Many thanks Point 1 and 2 was what I was mostly thinking. Point 3 I have seen barrel flex at very slow camera speeds at the handheld rifle level. One of those things that until you see it, your mind has a hard time accepting. Heat dissipation is also a fascinating thing with barrels, the higher the velocity in barrel the more heat it would generate and for a longer time.

Thank you I had suspicions on why the longer reloads but it was hard for my brain to accept coming from the handheld caliber world. I expect the differences only grow exponentially in line with the caliber of the barrel.

[James 296]

1. is only true if you have not properly balanced the barrel. Lots of examples out there of sailors elevating barrels by hand with no assistance, however 2. comes into play which is where a hand crank comes in, which is even included on ships like the Iowa's. With most of the machinery in a turret is there to keep the momentum of the barrel in check. Think of a barrel as a hammer on the end of a spring, as long as nothing acts on it. It's nothing to be a afraid of but get that thing moving, like say a storm, and you'll quickly find it will start smashing everything in it's way.

If you're curious, their is a book out there (forget the name) that talks about how well a barrel is balanced, can not only affect the aiming spend and accuracy of tanks but also the speed of the tank as well.

[WhiteTemplar[SG]]

Main reason is to have game balance. To add in a trade off between accuracy and RoF. If you look at the US 14/L45 vs 14/L50 in real life the L50 had the same if not better RoF as the L45.

[Ninjafroggie]

Originally posted by WhiteTemplarSG:

Main reason is to have game balance. To add in a trade off between accuracy and RoF. If you look at the US 14/L45 vs 14/L50 in real life the L50 had the same if not better RoF as the L45.

yeah but that was due to improvements in shell handling tech, gunlaying tech, improved gun design and forging, and other factors that had little or nothing to do with the actual length of the guns.

Really the main concern at play is heat...longer gun tubes mean the burning propellant spends more time in the barrel, increasing the heat it absorbs. Hot metal both warps and loses strength, and that's really really bad when it comes to large cannons, not just because of loss of accuracy, but because of the risk that the pressure in the tube when fired could cause it to fail in catastrophic fasion. You can easily find footage of US ships engaged in shore bombardment duties in wwII where sailors are spraying the guns with water hoses to cool them down. This is, in fact, a major limitation even with modern field artillery pieces, and is the reason why modern gun systems have both a maximum rate of fire and a sustained rate of fire that is much lower than the maximum. The M777 155mm gun used by the US today, for example, can fire 4 rounds a minute, or 2 rounds per minute sustained fire. It can only keep up that 4 rounds/min rate of fire for 2 or 3 minutes before the gun tube gets too hot to safely continue using it at that rate.

[Artificial Insanity]

Originally posted by WhiteTemplarSG:

Main reason is to have game balance. To add in a trade off between accuracy and RoF. If you look at the US 14/L45 vs 14/L50 in real life the L50 had the same if not better RoF as the L45.

I feel the argument that this isn't just "game balance" is proven by the fact naval cannons were presumably not made to have the absolute longest barrels possible.

If longer barrels didn't have diminishing returns and disadvantages, the ultimate warships would just have cannon breeches in the stern and multi-segmented barrels running the length of the ship, separating the segments between shots to vent exhaust gasses like some glorious steampunk monstrosity.

Now that I've described it, I realize that would be awesome in some kind of sci-fi anime...but definitely not something from the early 20th century.

[Ninjafroggie]

Originally posted by Artificial Insanity:

Originally posted by WhiteTemplarSG:

Main reason is to have game balance. To add in a trade off between accuracy and RoF. If you look at the US 14/L45 vs 14/L50 in real life the L50 had the same if not better RoF as the L45.

I feel the argument that this isn't just "game balance" is proven by the fact naval cannons were presumably not made to have the absolute longest barrels possible.

If longer barrels didn't have diminishing returns and disadvantages, the ultimate warships would just have cannon breeches in the stern and multi-segmented barrels running the length of the ship, separating the segments between shots to vent exhaust gasses like some glorious steampunk monstrosity.

Now that I've described it, I realize that would be awesome in some kind of sci-fi anime...but definitely not something from the early 20th century.

both sci-fi and anime are way ahead of you there, bud. The wave motion cannon from space battleship yamato, the ion cannon frigate from homeworld, the death star...

[wolfstanbjord]

I am not surprised on the diminishing returns, I know from small arms there is always a point where extra length stops giving any appreciable velocity gains no matter how slow burning the powder.

Dependent of course on many factors, and some times its not just a straight line on velocity gains or losses via barrel length addition or subtraction. I know with the average 54R surplus round there's a sweet spot where the velocity doesn't drop, around 23 inches I think it was. I would be curious to know if there is such a phenomenon among the larger bore naval guns as well.

[Aleks96]

Originally posted by AdmiralTigerclaw:

Longer barrel is in fact, heavier, yes. There are several knock-on effects.

1: Heavier barrel needs bigger, more powerful elevation machinery, to be stuffed into your turret. Stuffing more things into the turret means less room to move properly for the loading crew. Slowing them down slightly.
2: Longer heavier barrel is a longer, heavier tube that is more susceptible to storing momentum and flexing if it moves fast. Too much flex and you deform the tube, and your gun is now a worthless lump of metal a few dozen tons heavy.* So it must move proportionally slower to prevent damage in the event of flexing.
3: Longer barrel means more tube that needs to have gas evacuated, and time to cool. How much, I don't know. But you don't want to open the breech into the turret and get a lung full of freshly ignited high TNT combustion product (smoke), and you don't want to deform your gun from overheating it... see point 2.





*At the scales of battleships, all your metals and steels are actually quite flexible and/or brittle. War machines of this nature were are always operating at the very fringe of material science and represent, in most cases, the very edge of what you can MAKE them do.

based answer, always wondered the same question as OP

[James 296]

Originally posted by Artificial Insanity:

Originally posted by WhiteTemplarSG:

Main reason is to have game balance. To add in a trade off between accuracy and RoF. If you look at the US 14/L45 vs 14/L50 in real life the L50 had the same if not better RoF as the L45.

I feel the argument that this isn't just "game balance" is proven by the fact naval cannons were presumably not made to have the absolute longest barrels possible.

If longer barrels didn't have diminishing returns and disadvantages, the ultimate warships would just have cannon breeches in the stern and multi-segmented barrels running the length of the ship, separating the segments between shots to vent exhaust gasses like some glorious steampunk monstrosity.

Now that I've described it, I realize that would be awesome in some kind of sci-fi anime...but definitely not something from the early 20th century.

Not as sci-fi as you might think. there was an actual ship (and two at that) that was bulit with that idea and I think Drachinifel did a video on that wacky ship.