Naval Gun droop.

[BurnitBlue]

While watching some videos of modern naval battles it seemed so dramatic and exciting to watch.. One thing puzzled me though. The barrels of the mighty guns pointed up at about 30 degrees then loud deep bangs lots of smoke, then, after firing the round, the whole group of barrels attached to one "battery" would lower down to the horizontal. Why? It cannot be recoil, so I googled for the answer. Came up against a persistant explanation that the heat of the barrel after firing rounds caused the barrels to droop due to weight like in a bend. Come off it. Even I, who spent most of my service time in the RAF I could see that this was BS. I was obviously using the wrong words in the question but I can not get past this first answer.

I am still interested in the answer so I would be grateful to any ex navy seaman for the reason for this. My daughter thinks the barrel lowers to the horizontal to enable more shells to be pushed into the chamber. I think she is wrong but I am still impressed that she made a pretty good stab at the answer. Anyway, hope someone knows why those mighty guns behave this way.

 

[colind3782]

I'm inclined to agree with your daughter's explanation.

 

[Poignard]

To reload

 

[capnsensible]

Reload. There are lots of factors taken into account on thebold big calibre guns like drop but its teensy. Added all together though can make a difference so were factored in during a shoot. Think of a racing yacht making loadsa tiny adjustments to sails to go faster.
Many long years since I was a young rn apprentice in a 4.5 twin turret during a shoot. Hot oily and very flippin bangy!
Try perhaps the museum at priddys hard for more stuff. I found on Google once a USn training movie about big stuff too.

 

[38mess]

The guns have to level up to the reload mechanism which is fixed. The breach opens and a shell is pushed in. I think.

 

[BurnitBlue]

Thanks for the speedy answer. I will have to tell my daughter she was right. I know I will never hear the last of it. Fascinating stuff though. In the RAF i never came across anything bigger than the old Aden guns .303 I think (or a bit bigger). These were superseded by missiles very soon after I joined up.

To see those massive guns moving in such a controlled and majestic way was almost like a ballet if the reason for their existance was ignored. The engineering is most impressive. Operating those guns must have needed lots of oil to get them moving so smoothely. Health and safety must have had kittens when looking at the enormouse weight of the moving parts so close to human flesh. Thanks again.

 

[jwilson]

As others have said, for reloading very heavy shells. Serious land-based artillery recalculates aim angle slightly higher for each successive round as the barrels are hotter and have expanded (not drooped) and the barrels also wear away a few microns from friction, fractioannly reducing muzzle velocity. Not sure naval gunnery is quite as precise being based on a moving floaty thing.

 

[BurnitBlue]

Reload. There are lots of factors taken into account on thebold big calibre guns like drop but its teensy. Added all together though can make a difference so were factored in during a shoot. Think of a racing yacht making loadsa tiny adjustments to sails to go faster.
Many long years since I was a young rn apprentice in a 4.5 twin turret during a shoot. Hot oily and very flippin bangy!
Try perhaps the museum at priddys hard for more stuff. I found on Google once a USn training movie about big stuff too.

Yes I can imagine the heat from a 1/2 ton shell being propelled along a tight fitting cylinder being enough to cause enough droop to bend the barrel. Also the rifeling causing such a weight to spin along the whole length would could cause enough twist to effect subsequent accuracy. Minor adjustments without computers must have been based on art and experience.

Oh well back to Hugo Boss.

 

[scottie]

Thanks for the speedy answer. I will have to tell my daughter she was right. I know I will never hear the last of it. Fascinating stuff though. In the RAF i never came across anything bigger than the old Aden guns .303 I think (or a bit bigger). These were superseded by missiles very soon after I joined up.

To see those massive guns moving in such a controlled and majestic way was almost like a ballet if the reason for their existance was ignored. The engineering is most impressive. Operating those guns must have needed lots of oil to get them moving so smoothely. Health and safety must have had kittens when looking at the enormouse weight of the moving parts so close to human flesh. Thanks again.

Health and safety would definitely ban them for the result of being used alone

 

[BurnitBlue]

As others have said, for reloading very heavy shells. Serious land-based artillery recalculates aim angle slightly higher for each successive round as the barrels are hotter and have expanded (not drooped) and the barrels also wear away a few microns from friction, fractioannly reducing muzzle velocity. Not sure naval gunnery is quite as precise being based on a moving floaty thing.

I agree the moving floaty aspect of naval gunnery must be the reason the Scharnhorst (spelt wrong) was straddled so many times before one shell actually hit it. Not that the RAF bomber command did any better against the Tirpitz. Lots of youtube videos about repeated attacks giving the Tirpitze a good soaking before one big one turned it over.

 

[john_morris_uk]

As others have said, for reloading very heavy shells. Serious land-based artillery recalculates aim angle slightly higher for each successive round as the barrels are hotter and have expanded (not drooped) and the barrels also wear away a few microns from friction, fractioannly reducing muzzle velocity. Not sure naval gunnery is quite as precise being based on a moving floaty thing.

NGS is remarkably accurate and there has to be intentional variation of the aim to avoid the shells landing too close together nowadays. All the infantry I've ever worked with have been extremely grateful and impressed when they receive NGS. Putting the ship close enough inshore to where the target zone is puts other constraints on the situation though. The solutions for aim are calculated continuously as the ship moves... Don't underestimate the 45 main armament of a Frigate or Destroyer as a highly effective gun. You may be interested to know that the turret is entirely automated with no-one in it nowadays. (I don't think I'm giving anything away that isn't in the public domain with this post...)

 

[black mercury]

I believe the Americans invented guns that were able to reload without having to be lowered and reaimed during World War 2. It slowly became more widespread. Hugh difference in the rate of fire.

 

[Poignard]

Hee's an interesting free ebook from Project Gutenberg about US battleships in the early years of the 20th century :

The Project Gutenberg eBook of With the Battle Fleet, by Franklin Matthews.

 

[Blue Sunray]

 

[Whitlock]

What I have always found interesting is that the guns on a cruiser like Sheffield were all controlled by a gunnery director who aimed and fired a broadside with a single trigger.

 

[38mess]

Yes I can imagine the heat from a 1/2 ton shell being propelled along a tight fitting cylinder being enough to cause enough droop to bend the barrel. Also the rifeling causing such a weight to spin along the whole length would could cause enough twist to effect subsequent accuracy. Minor adjustments without computers must have been based on art and experience.

Oh well back to Hugo Boss.

I believe they had a basic aim computer, they also had to take the curvature of the earth into their calculations, air temp, weather, sea state. Punch it all into the computer.

 

[BurnitBlue]

I believe they had a basic aim computer, they also had to take the curvature of the earth into their calculations, air temp, weather, sea state. Punch it all into the computer.

Must have been something like a mechanical Babbage machine. Brass gears and cogs. Whitlock mentioned broadside shooting. Thought that was for Pirate movies because the recoil of a modern set of guns would capsize the ship. Not to mention all the rivits falling out. I read that somewhere.

I always thought it would be more fun in the Navy because everyone on board, even cooks and clerks had their battle stations. Unlike the RAF where only a handfull of aircrew faced the guns. Safe, maybe, but boring. I was ground crew on the dispersals which was as exciting in mostly wet, cold, waiting for the dawn return flights as it ever got. Not really complaining. The pub was always a bike ride away.

 

[Poignard]

I believe they had a basic aim computer, they also had to take the curvature of the earth into their calculations, air temp, weather, sea state. Punch it all into the computer.

 

[DownWest]

I was treated to a tour of Vanguard, shortly before she was scrapped. It included a demo of the 15 inch guns being loaded. Single hoist up from the magazine with several vertical sections for the charge and the gun was fairly level to push in the cordite sacks after the shell. The lift was then dropped back down with a resounding crash while the guns were aimed.

 

[Poignard]

What I have always found interesting is that the guns on a cruiser like Sheffield were all controlled by a gunnery director who aimed and fired a broadside with a single trigger.

This is HMS Gambia, my first ship, on a visit to Rotterdam in 1960 and looking pretty smart, although I don't remember how she got that dent!

The gun director can be seen above the bridge.

If that got knocked out the guns could be controlled locally.

During my 2-1/2 years in her she never fired at anything in anger but we had plenty of gunnery exercises, firing at towed targets.