Do Battleships move sideways when they fire?

[Heibges]

The text by the naval officer is ambiguous as to whether it "moved" as in propelled the ship through the water, or whether it just rocked the ship violently.

[ASWnut101]

Originally Posted by NEON DEON

Steve,

While the person you speak of wrote the article, he did not post the formula that is in the article.

Besides, even if he did write that formula he has no degree let alone one in physics.

So Steve what I am getting is that you claim that the picture I posted is fake and you are dismissing the descriptions of big guns firing given by an Officer of the United States Navy who actually served on board the Battleship North Carolina as Senior watch officer.

Two pertinent quotes from Lieutenant Ben Blee of the Battleship North Carolina:

“The force of the blast of the 16-inch guns could literally move the ship through the water.”

“No matter how one might try to brace his body in advance, there was no way to avoid bruises inflicted on elbows, knees and shins, as the entire ship lurched in angry recoil with every main battery salvo."

PLEASE tell me how he noticed the guns "literally moved the ship through the water," when he had to be inside. With that kind of recoil that he describes, if he were above decks he would have been thrown completely off the ship (As in "Man overboard!").

[Polak]

Don't forget that Sailor Steve served in the US Navy, so he has every right to question that navy officer.

[NEON DEON]

Originally Posted by Heibges

The text by the naval officer is ambiguous as to whether it "moved" as in propelled the ship through the water, or whether it just rocked the ship violently.

The words movement and lurched are in no way ambiguous.

[NEON DEON]

Originally Posted by ASWnut101

PLEASE tell me how he noticed the guns "literally moved the ship through the water," when he had to be inside. With that kind of recoil that he describes, if he were above decks he would have been thrown completely off the ship (As in "Man overboard!").

Did you miss the point that he was the senior watch officer.

[ASWnut101]

No, I didn't.


I don't understand how he could know that the ship would "lurch" so violently that it threw everything (including people) around, cause interior damage even though he was a watch officer, and that he could maintain enough balance to realize that the ship was moving and it was not simply the pressure differences on his middle ear that would cause him to think that he was moving.

Want a demonstration? Go to a big open space, hold out your arms (for the dramatic effect), and spin around really fast for twenty full revolutions. Now stop suddenly. Look! The ground is moving!

The huge blast from 9 sixteen-inch cannon firing at once (fast enough that you cannot tell the time between shots) causes UNBELIVEABLE air pressure forces in and around the ship, hatches closed or not. This major increase in pressure causes wonders on the ear structures, especially the middle ear (that controls balance). As such, he would have thought he was moving simply when he was only being thrown around by the immense air pressure wave from the salvo. When he got to his feet, he still would have thought he was moving, yet he is only being tricked by his own brain.


Jesus, I feel like such a medical-nerd. Maby I am...

[joea]

Originally Posted by NEON DEON

The words movement and lurched are in way ambiguous.

How the heck could the ship move so violently and such a distance as implied by your photo? (You read the other explanation did you not about the other side being obscured?) Did you see the video clips? How much movement are we talking here according to you? One inch? 10 yards? 100 yards?

Besides looking at your pic again those are shock wave patterns from the guns firing...

Again from the blasted article http://www.navweaps.com/index_tech/tech-022.htm

What looks like a side-ways wake is just the water being broiled up by the muzzle blasts. The ship doesn't move an inch or even heel from a broadside.
The guns have a recoil slide of up to 48 inches and the shock is distributed evenly through the turret foundation and the hull structure. The mass of a 57,000 ton ship is just too great for the recoil of the guns to move it. Well, theoretically, a fraction of a millimeter.
But because of the expansive range of the overpressure (muzzle blast), a lot of the rapidly displaced air presses against the bulkheads and decks. Those structures that are not armored actually flex inwards just a bit, thus displacing air quickly inside the ship and causing loose items to fly around. Sort of like having your house sealed up with all windows and vents closed and when you slam the front door quickly the displaced air pops open the kitchen cabinets.
R. A. Landgraff

You think BB designers would be so incompentent as to not put good recoil mechanisms in? How coul you fight in ship that moves as much as you seem to think?

[Lagger123987]

Originally Posted by Sailor Steve

Those videos show nothing but the guns firing and the camera shaking. What's your point?

As to the photos, look again at the overhead shots accompanying the article: no bow wave, just water being pushed away by the blast. I say the other ones are fake.

I'm just tyring to impress people, jezz.

[NEON DEON]

Originally Posted by joea

How the heck could the ship move so violently and such a distance as implied by your photo? (You read the other explanation did you not about the other side being obscured?) Did you see the video clips? How much movement are we talking here according to you? One inch? 10 yards? 100 yards?

Besides looking at your pic again those are shock wave patterns from the guns firing...

Again from the blasted article http://www.navweaps.com/index_tech/tech-022.htm

You think BB designers would be so incompentent as to not put good recoil mechanisms in? How coul you fight in ship that moves as much as you seem to think?

Joea,

The recoil does not negate the effects of momentum and inertia but only prolongs it long enough for the shell to depart the gun before the end of the 4 foot recoil thus maintaining an accurate shot.

As for the blast and pressure, The Conn of the battleship North Carolina is armored.

I am sorry if you were mislead by the blast ripples in regards to the picture I posted. However, if you go back you will find an earlier post of mine right after the post of the picture where you will see my comment of the blast ripples and much smaller bow wake.

Now, as for the fraction of a milimeter, no where in the original article does it post the formula to arrive at that conclusion. It leaves you with only the Conservation of momentum formula that ends in 6 inches PER SECOND. So in essence the formula they posted proved that after the the broadside the ship traveled 1,800 feet in an hour.

Why on earth would you pick the largest BB at maximum weight (58,000 tons) if you wanted to be conclusive on the point that a battleship does not move when you fire a broadside is a mystery to me.

If you use the standard displacement of an Iowa class BB 45,000 tons(not 58K) and use the actual mass of the entire load in the gun that is 3,405 lbs (not just the 2700 lbs projectile, unless of course you think the mass of the charge is not in the gun.) Using the formula they provided gives 9 inches PER SECOND.

And if you use the North Carolina as your model at a standard displacement of 35,000 tons the figure expands to about one foot or 12 inches PER SECOND.

And that brings me back to the USN officer I quoted earlier.

The quoted words were: "literally move the ship through the water."

Websters definition of literal not mine:

"1: according with the letter of the scriptures 2 : adhering to fact or to the ordinary construction or primary meaning of a term or expression. 3 : free from exaggeration or embellishment - literally <the literal truth> 4 : characterized by a concern mainly with facts."

So. No way is that line from Lt. Ben Blee USN ambiguous.

As for the total movement of the ship after a broadside, Its way more than a fraction of a milimeter and much less than 1,800 feet.

[joea]

Its way more than a fraction of a milimeter and much less than 1,800 feet

Very precise, too bad you and the other fellow are the only ones in the world who think that.

Come on people this is not a fuzzy question, there has to be a precise answer to it!!

[NEON DEON]

Originally Posted by joea

Very precise, too bad you and the other fellow are the only ones in the world who think that.

Come on people this is not a fuzzy question, there has to be a precise answer to it!!

Yes I know its incredible to think a USN senior watch officer who also was an intel officer would have been good at observation!:p :p

After reviewing such things as kinetic hydrodynamic drag, static hydrodynamic drag, and it's effects on inertia I have decided to E mail myth busters and let them figure it out. Who knows maybe they will turn it into a show!

[jumpy]

Wow, Looks like you bunnies are getting all excited

I think it's fair to say, that firing the main batteries wouldn't have the effect of some new and totally impractical drive system... as for making the ship lurch or shudder or vibrate, then yes, absolutely and without question. Any such 'real' motion of the entire vessel in the opposite direction to that in which the main guns were facing upon firing is silly or so small as to be virtually un-noticeable in any practical sense.
After all, if you fire a shotgun, you don't suddenly get propelled backwards, you absorb the recoil... so does the ship and to an infinitesimal degree, so does the water surrounding the ship. Surely if the main guns were so powerful at to alter the course of the ship, then the designers would have had to think twice before continuing?

Seems like common sense to me?

But hey, I'm just speculating here...:rotfl:

But if I was to say for sure what the movement of the ship was under main battery firing conditions, then it's definitely 10... er, 10.5368442179 blerns. :hmm: yup, for sure.

[Etienne]

Originally Posted by NEON DEON

PLEASE tell me how he noticed the guns "literally moved the ship through the water," when he had to be inside. With that kind of recoil that he describes, if he were above decks he would have been thrown completely off the ship (As in "Man overboard!").

Did you miss the point that he was the senior watch officer.[/quote]

Wouldn't the BB's, when they were still used in later years, have been equipped with dual axis doppler log? These things have been around for a while, AFAIK. And they give you sideway speed. (Extremely usefull when you're trying 100000 tons of something right up to a flimsy wharf)

[Sailor Steve]

Originally Posted by NEON DEON

Why on earth would you pick the largest BB at maximum weight (58,000 tons) if you wanted to be conclusive on the point that a battleship does not move when you fire a broadside is a mystery to me.

If you use the standard displacement of an Iowa class BB 45,000 tons(not 58K) and use the actual mass of the entire load in the gun that is 3,405 lbs (not just the 2700 lbs projectile, unless of course you think the mass of the charge is not in the gun.) Using the formula they provided gives 9 inches PER SECOND.

First of all, there was never any such thing as a 45,000-ton Iowa class battleship. Forty-five thousand tons was the design weight. The light load weight at sea was 48,000 tons, and they replaced used fuel and supplies with sea water to maintain the 57,000-ton full load displacement. The reason for this was that when the displacement changed the metacentric height changed, which in turn affected the rate of roll, thus changing all the fire-control solutions.

Second, any mass behind the 2700-pound shell (i.e. a cartridge, which these guns don't have) would be part of the weight on the other side of the blast, thus resisting the recoil, not adding to it. The firing charge's mass is all converted to energy, so it is the blast itself, and doesn't contribute to the mass either way; so no the mass of the charge is not in the gun.

Third, that is still the only photo which shows that bow wave, all others not having one (and there are many, many others.

So we now have the word of a man who was there versus the word of a man who was there many times and finished his career rebuilding and testing the ships in question. Tell my who I should believe.

[NEON DEON]

Standard tonnage for a Iowa class BB 45 thousand tons.

Mean (That means average, not the heaviest, not the lightest, but average.) load of a wartime Iowa class. 52,000 tons. Like I said before if you want to disprove it you have to make it fit all cats not just the heaviest. Also WW II BB's were equipped with fire control computers that factor in every movement of the ship as well as made adjustments to height roll and even accounted for bounce. No such weight restriction was put on these ships and they did indeed take on ballast but that was to counter roll due to high seas not standard operation.

Six 110 lbs charge bags went into the guns along with the projectile and bursting charge on the nose to total 3,405 lbs each. The breaches were closed and when fired, the entire mass came out the business end of the gun at the same speed of the projectile. In other words the charge is projected out the end of the gun contributing to the momementum put on the gun and its platform. No way is the charge behind the blast it is the blast. The charge is in the gun.

Stern view of the BB 45 USS Colorado firing a 16 inch broadside:



Ben Blee spent the war on the USS North Carolina while the guy who wrote that article was in diapers. Please show me when the guy that wrote that article was present during a live fire exercise of a battleship broadside.