Artillery Ballistics?

[densa44]

I seems that a 16" navel shell with a MV of less than 3000 feet/sec travels 20 miles. In our small caliber rifles even with much higher mussel velocities and good BCs don't get nearly that far.

The naval shells weigh a ton or more, is that the difference? Oh BTW their very expensive gun barrels are only good for about 300 shots.

The gun barrels are about 50 calibers long.

What gives these shells such long range? If it is mass, what would be the maximum range a rifle could get if it had much heavier bullets?

Thx guys.

[dgitz]

Originally Posted by densa44

The naval shells weigh a ton or more, is that the difference?

You nailed it. More weight means more energy and momentum.

[elkdump]

The 16 inch Navel Guns are Magnums ,,

Many guys hunt deer with Magnums ,,

Some of them are called "Short-Magnums" , these don't shoot so far

[nekred]

Momentum..... which is bled off through KE degradation....(friction)

KE = 1/2 (mass x velocity x velocity)

Momentum = MV

a low mass high speed projectile with same KE as a high mass low velocity projectile.... momentum is not constant....

Velocity bleeds off where mass does not.... and how velocity bleeds off is determined by drag which is also affected by shape of projectile.... throwing a wiffel ball or a golf ball of equal weight at same speed you get different results...

here is a better way of thinking about it.... how many 30 caliber bullets does it take to make up a single naval round.... then calculate the surface area of each round vs. the surface area of all rounds packed together into one shell and that affects your drag or coefficient of friction..... or think of a sky diver.... does he weigh any different after his chute opens.... gravity has not changed... so his KE added from gravitational pull is negated by KE bleeding off through drag....

to get a small arms projectile to travel that long distance is not realistic unless you come up with other technology... such as a rail gun which can accelerate small very heavy dense projectiles to incredible speeds but would need a "barrel" hundreds of miles long.... this has been considered as a means of launching single pods into space or for very high speed travel... as the acceleration is low enough to make the trip survivable....as long as heat is allowed to dissipate or not create heat such as using a vacuum....

now something that changes the whole situation is that we are always assuming that the projectiles are travelling through a medium like air... when a projectile is supersonic it really is not travelling through it, it is more akin to burning a hole in it....

The other factor is gravity.... eventually both projectiles are overcome by gravity and as the drag increases and projectile slows down gravity has more effect until projectile is grounded....however if projectile is able to get far enough from earth's surface where its forward motion is able to continuously equal its gravitational motion then object will circle the object indefinitely (orbit) however if it is in atmosphere this will not happen unless projectile has its own way to maintain motion....

Now if we take the medium away and move to the vacuum of space (drag and gravity no longer factors) both projectiles will act the same....

[nekred]

Many people believe KE and momentum are the same....

they are integrals and derivatives of one another.... they are related like speed and acceleration but two totally different things...

I have seen ridiculous stuff posted in articles especially when it comes to archery about this magical factor called "retained kinetic energy" kinetic by its very definition means it cannot be retained or stored because if it could it would be "potential" energy..... thus what they are really talking about is momentum but because most people have not taken first year university physics they get it all mixed up....(or even grade 12 physics)

short answer to original post is momentum....

[nekred]

Same people always refer to how some bows are magical and have more KE....

it all comes down to the projectile.... no matter the bow they all will shoot a heavy projectile slower, and a lighter projectile faster... however this is all on a curve for each bow and each bow curve is different and depending on draw cycle... some bows shoot lighter projectiles more efficiently than heavier ones and vice versa.... just like gear ratios.... some gear ratios are better for towing and others better for racing.... assuming constant engine power...

1000 horses in high gear ratio may tow better than 500 in a low gear ration.... or maybe not.... depending on torque

horse power and torque work like KE and momentum.....

what is the old saying torque does the work while horsepower takes the credit

[densa44]

First year physics was a very long time ago. Does the BC measurement really calculate the drag caused by air friction.

I recall "Big Bertha" the Paris gun had a range of 75 miles and shot at an elevation of 55 degrees or more. The reason given for the very long range was it (the shell) left the atmosphere and traveled for a time in space before it re-entered the atmosphere.

If any one knows, after the 300 shot barrel life is reached what actually happens to the accuracy? The barrels have a "sleeve" how are they replaced on a battleship?

[catnthehat]

Originally Posted by elkdump

The 16 inch Navel Guns are Magnums ,,

Many guys hunt deer with Magnums ,,

Some of them are called "Short-Magnums" , these don't shoot so far

Well, that explains EVERYTHING (I think )!!
Cat

[norwestalta]

I don't know about the 300 round shelf life but I can't recall the barrels ever being changed on the ships I was on. Wasn't much accuracy hell we were lucky if the 3"guns would shoot. I do recall t-33 pilot getting excited when we shot the tow wire of the target we were shooting. This was with the 57 mm. There is a you tube video of Canadian navy shooting a ship for target practice. I wasn't part of that but we used to deploy something like a big beach all that we'd have a fireex on. We'd also practice ngs (naval gunfire support) on san clementa island off the coast of California. Our guns weren't used for precision work more for air defense with he shells.
Forgot to mention that the 50cals would get changed every couple hundred rounds. Never threw them out just let them cool.

[marxman]

its the length of the artillery shell gives it a much higher sectional density even though a bullet being solid metal is denser. so much more mass behind the equivalent frontal area is going to increase its b.c. there is also the ratio of mass to surface area although i dont know what that is the two projectiles being of different densities but a gallon of water takes longer to freeze than a cup because of its smaller surface area to mass ratio. similarly the bigger projectile will be less affected by the air.

[nekred]

Originally Posted by densa44

First year physics was a very long time ago. Does the BC measurement really calculate the drag caused by air friction.

I recall "Big Bertha" the Paris gun had a range of 75 miles and shot at an elevation of 55 degrees or more. The reason given for the very long range was it (the shell) left the atmosphere and traveled for a time in space before it re-entered the atmosphere.

If any one knows, after the 300 shot barrel life is reached what actually happens to the accuracy? The barrels have a "sleeve" how are they replaced on a battleship?

Ballistic co-efficient is a number created from calculating the actual performance of the bullet.... The different shapes etc are all calculated in....

that is why a 180 grain ogive bullet is different than a 180 grain flatnose or a 180 grain boat tail is different than a 180 grain flatbase... it is basically a very quick expression of how much the bullet would slow down over its path extrapolated from its flight drop corrected for sea level...

[densa44]

Marks, are you sure about the water? Doesn't the larger volume contain much more heat than the cup and thus takes longer to freeze?

I guess if each ml were at the same temp, in the cup and in the gal, the surface area that was exposed to the lower temp would make a big difference.

[marxman]

to put it another way a four inch cube contains 64 cubic inches and has 96 square inches surface area. a one inch cube has 6 square inches of surface area for a six to 1 ratio of surface area to volume vs a 1.5 to 1 surface area to volume ratio of the 4 inch cube. so if you split the gallon of water into one cup sizes it would still be more heat in total than one single cup but if you put them outside they would freeze as fast as the single cup because you have exposed more area

[elkhunter11]

https://mathscinotes.wordpress.com/2...c-coefficient/

From that link

Modern long-range guns like the US Navy’s 16-inch guns are able to attain ranges in excess of 25 miles using an initial elevation angle near 45 degrees; their shells reach an altitude of approximately seven miles. Although their muzzle velocities are generally only about 2600 to 2800 fps, their enormous size and weight — in excess of 2000 pounds — gives them ballistic coefficients of around 15, which are 30 to 50 times as great as small arms projectiles!

[twofifty]

Elk has it.

16" naval gun velocities are not much different than what we get out of our
30-06 rifles with 180gr bullets, or most any non-magnum big game cartridge for that matter. I read that chamber pressures run in the 50,000 to 60,000 psi as well.

As the barrel wears, shot dispersion on/around the target increases such that the probability of a hit is lowered.

The firing solution is interesting because it took into account barrel droop, barrel wear, air density (round is travelling through multiple layers of atmosphere), ocean winds, and best of all the movement of both ships.

edit: the above was regurgitated from several naval artillery websites that are run by men who actually shot the big guns. My naval experience consists in having attended the commissioning of the current HMCS Ottawa. iow, zilch.

The Ottawa's ship-to-ship capabilities come from Harpoon missiles: no barrel wear and often a 1st round hit.

[petew]

But is it easier to pick fly poop from pepper or pepper from fly poop? and when you pick it and toss it which one travels farther?

[norwestalta]

Originally Posted by twofifty

Elk has it.

16" naval gun velocities are not much different than what we get out of our
30-06 rifles with 180gr bullets, or most any non-magnum big game cartridge for that matter. I read that chamber pressures run in the 50,000 to 60,000 psi as well.

As the barrel wears, shot dispersion on/around the target increases such that the probability of a hit is lowered.

The firing solution is interesting because it took into account barrel droop, barrel wear, air density (round is travelling through multiple layers of atmosphere), ocean winds, and best of all the movement of both ships.

edit: the above was regurgitated from several naval artillery websites that are run by men who actually shot the big guns. My naval experience consists in having attended the commissioning of the current HMCS Ottawa. iow, zilch.

The Ottawa's ship-to-ship capabilities come from Harpoon missiles: no barrel wear and often a 1st round hit.

The HMCS Ottawa and other city class frigates are designed for ASW roles. They have the harpoon surface to surface missile as well as sea sparrow missile which are for air defence. 57mm bofors and ciws are secondary defensive weapons. I can't recall the range of the 57mm but I'm thinking 8 miles.
The 280's (I don't know if there's any left in the fleet) are a command platform and primary purpose is AAW. These had standard missiles and a bigger gun on the bow then the frigates. I never sailed on the 280's (tribal class destroyer) so I can't remember the size of gun it.
I've got a couple of 57mm cases in Edmonton that I'll post one day when I get down there to take them.