High Velocity Main Guns

Started by Delta Force, March 15, 2011, 09:22:53 PM

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Delta Force

I was looking around on Navalweapons and came across the 9"/98 (22.9 cm) Mark 1. I was wondering if something along the lines of it would be useful for a ship around the 1920s. I can't find any information about what kind of armor penetration the gun was able to get, but given that it has around 63% the kinetic energy of the 14 inch gun from which it is derived with a very high velocity and has only 43% of the frontal area, which should give some pretty high sectional density. It would make for an accurate gun with the capability to carry nearly 4x the shells of a normal 14 inch gun and probably would have an excellent rate of fire. Thoughts on it?

http://www.navweaps.com/Weapons/WNUS_9-98_mk1.htm

Logi

The barrel would wear out faster than it can use up a normal gun's ammo stowage. With such a high barrel wear, it's safe to say it wouldn't be accurate very long.

In addition, the weight of the shell is a property of penetration on its own, simply making it have a High Muzzle Velocity will out work out well. This is in part due to the rapid bleed of muzzle velocity as the shell travels in flight.

Added to the fact that the 9"/98 projectile seems even lighter than a normal 9" shell and you have a weapon that is suited for use only as a novelty.

Guinness

I see a few potential issues here, especially for naval use:

1. It's heavy. At right around 100 tons, it's 116% of the 14"/50 it was derived from.
2. It's very long. I think issues like muzzle droop and whipping would have to be overcome. The length also makes designing mounts and fitting them on a ship more difficult.
3. High velocities likely mean the gun would wear out very quickly.
4. This example was never completed or fired, but if you look at the 3"/105 of the same program you can see that range for these high velocity sub-caliber guns wasn't any better than the conventional guns that provided their chambers, etc. The 3"/105 was derived from a 7"/45, but it's stated ranges per elevation seem pretty similar to those of the 7"/45.
5. At longer ranges, the higher velocity has few advantages, and some disadvantages. One can expect they would fall at a shallower angle, resulting in less deck penetration.

The advantage I can see would be at short range on relatively flat trajectories, but it would still deliver less kinetic energy for more shipped weight. Higher potential RoF would be offset by shorter barrel life, I suspect.

Logi

#3
I don't have time now, but I can run it through my program for the max range energy considerations, but it wouldn't* be very good.

*Fixed a typo

Borys

Ahoj!
I'm with Logi and Guiness - not worth the bother.
Borys
NEDS - Not Enough Deck Space for all those guns and torpedos;
Bambi must DIE!

miketr

Its a stunt weapon to fire at long range for PR reasons not for effect.

Michael

Logi

Ran through the tests firing the 9"/98 and 14"/50 at 45 degrees at the equator firing west to east.

The 9"/98 firing a 275 lb shell gets:
Striking velocity 1575.82 fps. 112 seconds in flight, drift 184.43 yds, angle of fall -50.47 degrees. Distance traveled, 619858.51 yds.

The 14"/50 gun (firing 1402 lb shell) it was derived from would get:
Striking velocity 1750.54 fps. 98 seconds in flight, drift 144.1 yds, angle of fall -48.71 degrees. Distance traveled, 48500.31 yds.

So energy of the two guns is 14.4 MJ and 90.5 MJ, respectively. It's pretty clear the 14"/50 is going to penetrate much better. Ofc, it is also apparent that the (9"/98 has longer range and a flatter trajectory, however, that advantage will disappear as the 9"/98 quickly wears down it's barrel).

Delta Force

Is that a typo for the 9 inch gun range? It is saying it can fire up to 352 miles with a very high degree of accuracy.

Logi

Yes it's a typo. Since I'm home now, I'll also give a more accurate reading (this requires running through it several times to get a dispersion, drift is just the horizontal drift for other reasons).

The 9"/98 that fires a 275lb at 5000 FPS:
Average striking velocity 1712.47 fps, 120 seconds in flight, dispersion area of 1067 yds, angle of fall -49.66, and average distance traveled 72,270.23 yds.


And the 14"/50:
Average striking velocity 1823.19 FPS, 99.5 seconds in flight, dispersion area of 851 yds, angle of fall -48.20, and average distance traveled 50,412.39 yds.

That would make the energy of the guns 17.03 MJ and 98.19 MJ, respectively. The 14" shell has about 6 times more energy on impact than the 9" shell. Note also that my program doesn't account for wind and with wind I should expect the 9" shell to lose a lot of accuracy due to it's light weight and high spin rate.

Interestingly enough, it seems the 9"/98 shell would have had to use supercharged propellant in order to reach it's desired 5000 fps, the average on normal propellant seems to be more akin to 4600 fps.

Delta Force

Can the program compare the two guns at closer range, say 20,000 yards? The gun would be more likely to be used at closer ranges given its flatter trajectory and lighter shell weight. I'd also like to see what kind of impact energy the 9/98 gets at the 50,000 yards maximum range of the 14/50, since the difference in range between the two guns is massive.

Logi

#10
I can't do it exactly, since it really takes only angle to get the range, but I'll test it out:

The 9"/98 that fires a 275lb at 5000 FPS gets comparable range at 30 degrees to the 14"/50's 45 degrees.
Average striking velocity 1382.84 fps, 81 seconds in flight, dispersion area of 378 yds, angle of fall - 41.73, and average distance traveled 50432.38 yds.

That would be an impact energy of 11.1 MJ.


At 20,000 yds?

9"/98 firing at 15 degrees:
Average striking velocity 911.58 fps, 39 seconds in flight, dispersion area of 112 yds, angle of fall -34.95, and average distance traveled 20499.24 yds.

That would be an impact energy of 4.8 MJ.

14"/50 firing at 15 degrees:
Average striking velocity 1294.21 fps, 36 seconds in flight, dispersion area of 92 yds, angle of fall -23.84, and average distance traveled 20676.11 yds.

That would be an impact energy of 49.5 MJ.


Realistically speaking, the only range at which the 9"/98 275lb shell would out perform the 14"/50 1402 shell at around 0-1 degrees. The problem with light shells and high muzzle velocity guns is that the shell bleeds velocity VERY quickly. Ofc, you could say the 9"/98 has the advantage of being able to reach ranges the 14"/50 can't but even then it's not going to be a firing distance where you have a remote chance of hitting something.

The advantage of the 9"/98? Well you notice it has a few seconds less time in the air and a lower dispersion at medium-high ranges than the 14"/50 and longer range, but I suppose that's about it.

At short range, the 9"/98 enters a more parabolic arc faster than the 14"/50 so it's oddly higher dispersion and flight time should be a result of that.

Blooded

regarding extreme high velocity guns...

Taken from Navweaps... http://www.navweaps.com/Weapons/WNRussian_71-57_m1932.htm

QuoteWhen work on the incomplete cruiser Krasnyi Kavkaz was restarted in 1927, it had been planned to fit her with eight 8" (20.3 cm) guns in four twin turrets.  However, it was quickly determined to be impossible to mount this much armament on the small and lightly constructed hull of this ship.  Instead, four guns of the smaller caliber of 180 mm (7.1") were installed.  These were 8"/50 (20.3 cm) Pattern 1905 guns relined down to 18 cm/60 (7.1").  These guns were to have had a very high muzzle velocity of 3,281 fps (1,000 mps) but initial trials showed that this would have given them a liner life of less than 10 rounds.  The guns were derated but even then their life was quite short.

The examples shown before should perform similarly. Metallugy is not up to it. Just not worth it.
"The black earth was sown with bones and watered with blood... for a harvest of sorrow on the land of Rus'. "
   -The Armament of Igor

Delta Force

Which program are you using Logi? I am considering developing a few ahistorical guns (like an 18+ inch gun for amphibious assault support seeing as the CSA has no islands) and that could prove useful in judging their performance.

Sachmle

Quote from: Delta Force on March 17, 2011, 01:33:43 PM
Which program are you using Logi? I am considering developing a few ahistorical guns (like an 18+ inch gun for amphibious assault support seeing as the CSA has no islands) and that could prove useful in judging their performance.

1) Huh? Like a mortor?

2) CSA has the Bahamas and Haiti, those are islands.
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TexanCowboy

Quote from: Sachmle on March 17, 2011, 01:37:42 PM
Quote from: Delta Force on March 17, 2011, 01:33:43 PM
Which program are you using Logi? I am considering developing a few ahistorical guns (like an 18+ inch gun for amphibious assault support seeing as the CSA has no islands) and that could prove useful in judging their performance.

1) Huh? Like a mortor?

2) CSA has the Bahamas and Haiti, those are islands.

Technically, every continent is a island, as they are all fully surrounded by water....(Ok, Eufasia might be stretching it...)

Anyways....what the heck would the CSA need an 18'' gun for that a couple of those http://www.navalism.org/index.php?topic=4692.msg55973#msg55973 can't handle? You'd be getting 2, maybe 3 times as many ships as you would with an 18'' gun, and the 7.5'' gun is already widely available....there's not much that you need anything bigger then a 13.5'' gun to demolish for coastal fortification here....I remember there was a big discussion over this a few months ago.