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Ant__.
02-08-2007, 05:15 AM
Following the Yamato Battleship thread I started Here (http://forums.ubi.com/eve/forums/a/tpc/f/857101043/m/2771096035) It got me thinking about those HUGE guns and recoil. Can anyone explain to me how Battleships like this fire their enormous guns without the ship rolling over in the opposite direction? I mean The Yamato had shells that weighed 3200 pounds - that's got to be one hell of a kick!

Am I making sense? I hope so! http://forums.ubi.com/images/smilies/blink.gif

Goose_Green
02-08-2007, 06:38 AM
I think their sheer size, weight and displacement is enough - probably something to do with inertia too.

Minoos
02-08-2007, 06:56 AM
Most guns have a recoil system to limit the 'kickback'.

http://img102.imageshack.us/img102/817/recoilrl2.jpg

Messervy
02-08-2007, 06:59 AM
A full broadside waights about 9,6 tonns. Compare that to 72.000 tonns.
That is 0.013 percent of the total weight.

Perhaps this is a way to understand why they didn`t roll over.

K_Freddie
02-08-2007, 07:43 AM
Errr M... the force would be equal to something like => 9.2 ton x muzzle velocity..

Someone might know the muzzle velocity of these big guns. http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

Minoos
02-08-2007, 07:44 AM
Messery forgets about energy !


Muzzle Velocity ( Bismark data (http://www.battleshipbismarck.com/bismarckclass/layout/11_bismarck_38cm.php) )
For naval shells: 800 kg (1.764 lb) shell: 820 meter per second (2.690 feets per second)
second)
I used a simple formula from http://www.bsharp.org/physics/stuff/recoil.html

Shell momentum = 820*800
Recoil speed for the Bismark : 820*800 / 51,000,000 = 0.013 meter per second.

This would not push aside the whole ship but force a noticeable roll.
That is where the gun recoil system is very important to reduce the roll and keep the firing precision.

Messervy
02-08-2007, 08:39 AM
No, I did not forget, but I`m a very poor mathematician so I didn`t want to venture in that particular area of calculations.
I knew someone would sooner or later come up with deatiled axplanation http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

OzzyBob
02-08-2007, 11:24 AM
i think i did read somewhere that after fireing a brodadside they acctualy moved sideways a few meters or so...

worst thing i ever heard is a field-howitzer 150mm the sound is deafening..can imagine what 18" guns sound like.

PhantomKira
02-08-2007, 12:55 PM
Here's an overhead shot of USS Missouri (BB-63) firing a full broadside. USS Missouri broadside (http://www.history.navy.mil/photos/images/h96000/h96814k.jpg) That's nine 16 inch shells weighing 1,900 to 2,700 pounds (850-1,200 kg) each. Can't tell from the photograph very well, but there doesn't seem to be much sideways displacement, or roll of the ship due to the broadside. A matter of mass, I guess, as Goose_Green already stated.

Ant__.
02-08-2007, 01:06 PM
*Sucks air through clenched teeth* I wouldn't want to be on the recieving end of that salvo!

Minoos
02-08-2007, 01:18 PM
I think the picture shows very much what kind of side effect there is...
http://img62.imageshack.us/img62/7861/effectop5.jpg

Messervy
02-08-2007, 01:35 PM
NO WAY!

The salvo lasts only miliseconds and on this picture is in it`s peak, while the wake was formed at least 3 seconds before the blast off.

Minoos
02-08-2007, 02:21 PM
http://forums.ubi.com/images/smilies/35.gif My imagination took me far away from reality?

Kaleun1961
02-08-2007, 03:06 PM
This was discussed a while back and I think I contributed an article which explained why there is no sideways shift of the ship. Ozzybob, what you have heard is a myth, ships do not shift several metres to the opposite of the salvo. The physical forces involved can be demonstrated mathematically to be insufficient to do so. Most of the energy goes into hurling that big shell from zero to muzzle velocity in a fraction of a second. The vast preponderence of energy is out the barrel, not away from the barrel.

Kaleun1961
02-08-2007, 03:08 PM
Check out this article:

Do battleships move...? (http://www.navweaps.com/index_tech/tech-022.htm)

And this one:

Speculative science (http://www.guardian.co.uk/notesandqueries/query/0,5753,-1045,00.html)

That last one mentions that the guns in a salvo fire at a tiny fraction of a second apart so that each shell does not interfere in flight with its neighbor.

Ant__.
02-10-2007, 02:13 AM
Thank you everyone! ....my head hurts now http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

AO1_AW_SW_USN
02-10-2007, 02:29 AM
I had a very rare opportunity to see the main batteries of the USS Missouri in action.

It was in 1987, and my dad's little tin-can destroyer and the Mighty Mo was conducting what's called a "Dependants Cruise" simultaneously. I was only 11 years old when I was standing on the bow of the USS Lynde B. McCormick (DDG-8) when the USS Missouri fired one practice round from her enormous gun. The ship I was on was about 1000 yards (approx. 1000m) from the Missouri's stern, and it felt like someone punched me right in the chest.

Now, I've seen sonic booms from F-14's and F/A-18's, but they have nothing on that kind of deafening power!

PhantomKira
02-10-2007, 08:26 AM
Watched a History Channel program on the sinking of the Bismarck last night. I recall one of the survivors saying that the ship did roll after a broadside, the event in question being her engagement with HMS Hood and HMS Prince of Wales. So, maybe she didn't have a (or an effective at least) recoil system in place? Sounds rather unlikely for a ship of such modern design. Then there's this (http://www.kbismarck.com/armament.html) (first paragraph, "roller track platform") which gives the impression that she did have such a system. AAAAK!! Can anyone point me toward conclusive reports one way or the other? (Diagrams would be wonderful!) Thanks!

Minoos
02-10-2007, 08:49 AM
There is without any doubts a recoil system.
Data from the Bismark gun states: Gun recoil 1,050 m (41,3 in).

Kaleun1961
02-10-2007, 11:54 AM
Phantom Kira, I would not discard all of the scientific information because one survivor said that Bismarck rolled after firing. Bismarck was a heavy ship and subject to the same laws of physics as other battleships. There are some problems with after-the-fact witness statements as every cop could tell you. I would not discount common sense physics because of the romantic notions of one sailor decades later.

turnip_tick
02-10-2007, 05:22 PM
I dont think that a crew member is the best witness as too whether the ship rolled or was pushed sideways. What we have to remember is that the Bismark was in a battle where there were shells landing all around her, and even some hitting her. additionally the concussion of her main battery surely felt awsome to those on board . Also she was in water. Obvious I know but still with waves on the ocean and all the near misses was the rolling sensation of the ship due to the recoil of the guns or due to the motion of the ocean.

With the bismarck being 118' wide how exactly would a crewman onboard who is busy fighting a battle know if the ship was moved sidways. they didn't have a GPS fix on their exact location back then. So with all due respect to the gentleman in the interview, I saw it too very interesting program. He simply would not have been in a position to know whether then rolling was caused by their own gun fire or that of the enemy or even just the natural ocean currents.

As it was once pointed out to me, Just because virtually all serial killers ate happy meals as children, doesn't mean that happy meals CAUSE serial killers.

PhantomKira
02-11-2007, 03:47 PM
Um, guys and/or gals, I didn't mean to indicate that I wanted to refute the laws of physics. Just mentioning that someone who was there with a 60 plus year old recollection of events thought he felt the ship list when the guns were fired. Yes, it was just one ship, with shells landing in the water around her, so there were definitely other factors involved, as always.

So, according to Minoos, a "roller track system" is the same as the system described above, a recoil system... different name for the same thing. Makes sense, just wasn't sure exactly what it was they were talking about in the article.

What's this about happy-meals and serial killers?

turnip_tick
02-11-2007, 04:26 PM
happy meals and serial killers. well simple really.
Just because "A" happened then "B" happened doesn't mean A=B. Then man felt the ship roll. thats fine and they were firing the big guns, also fine kind of like A and B but did A, the guns firing cause B, the rolling he felt. Physics says no.

Kaleun1961
02-11-2007, 08:17 PM
Well, you did ask for an explanation. I also posted links to a few articles in one of my earlier posts in this thread. This sort of thing is easy to find on the internet; just type in battleship gun recoil into a search engine and see what you find.