One of the arguments for the all big-gun ship was that the different caliber shell splashes are hardly distinguishable, so it interferes with spotting thus
fire control. Is it a real problem with centralized FC? Ballistic tables for both large and intermediate caliber guns are known (say 12" and 9.2").
If there's centralized FC, then both caliber guns are firing at the same distance, and shells, either 9.2" or 12" would fall around the same
point, and it would hardly matter which shot is spotted. Theoretically, at least.
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 P3D |
Mixed caliber guns and spotting |
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Posts: 814 ( 2-May-2008 23:49:03) |
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 NewGolconda |
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Posts: 3319 ( 3-May-2008 12:03:39) Commonwealth Moderator |
Its a fammiliar thought.
Of course, Dreadnought herself pre dated centralised fire control by six- eight years. In the 1908-1914 era, an aloft team on a pre dreadnought or dreadnought will be providing centralised ranging, spotting and clock/dumeresq calculations to individualy aimed guns, which use telegraph or follow the pointer sights for range with local training. |
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Lionage |
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Posts: 8 ( 3-May-2008 13:38:04) |
Mixed calibre guns work for short ranges (under 5,000 yards or so), where it is possible to fire with open sights, or where the gunner can see the shell in
flight. As ranges increased, gunnery became reliant on spotting the fall of shot. The inability to tell which gun created which splash led to three
innovations: the all big gun ship (Dreadnought, South Carolina), fire control computers (Dreyer and Pollen tables) and centralised gunnery control (director
firing).
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P3D |
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Posts: 815 ( 4-May-2008 09:27:26) |
Lionage,
my point is that you don't have to tell shell splashes apart. |
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hoist40 |
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Posts: 1009 ( 4-May-2008 13:22:42) |
my point is that you don't have to tell shell splashes apart. Agreed, you look for the salvo splash, not the individual splash. In fact when firing all 12 inch guns its even harder to tell the individual splashes apart then if you are firing a mixed armament. That's why they started firing the turrets in salvos so that you did not worry about what individual turrets were doing since there not much chance of telling which 12 inch splash is which I think the major driver of the early all 12 inch gun ships was the harder hitting and more accurate at long range feature not anything about shell splashes. Then as fire control systems came into play it was easier to deal with only one caliber of shell since the performance was the same. It certainly was possible to build a fire control system which could handle two separate types of guns but range kept on increasing and the smaller gun became more and more ineffective and inaccurate at those long ranges However in a short to medium range fight such a ship might be very effective. Also it would require you to make your fire control more complicated as it became more electro-mechanical because you would have to deal with two different range tables and you would still have the problem at longer range where the smaller guns accuracy falls off more and has a shorter maximum range. Does anyone know if any of the Pre-Dreadnoughts tied their 12 inch and intermediate guns into the same fire control system? I would think that the superimposed 12/8 inch US turrets would use the same fire control once ranges increased and centralized fire control systems were installed |
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NewGolconda |
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Posts: 3322 ( 4-May-2008 13:45:10) Commonwealth Moderator |
This flowchart of a modernised RN pre dread in 1914 seems to indicate seperate circuits and clocks for the secondary armerment.
http://www.gwpda.org/naval/fcchart.htm There is an excellent article on Russian arrangements in a squadron of pre dreads during WWI, printed in Warship. I agree that the Dreadnought design history suggests greater fire power, and better performance at range had a lot to do with the decision to adopt a uniform battery. As for spotting mix calibres in pre dreads. Most pre dreadnoughts featured the 12in/6in mix, with such fundamentally different ballisitics that it really needs no further comment. For the ships with an intermediate calibre, 9.2in guns have a different time of flight and rate of fire to the twelve inch, and pre director, probably a different point of aim (http://www.gwpda.org/naval/nrnzturr.htm).
Last Edited By: NewGolconda
4-May-2008 14:08:25.
Edited 1 times.
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Lionage |
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Posts: 9 ( 4-May-2008 13:47:28) |
P3D wrote: You wouldn't have to if you could guarantee your range tables for guns of different calibre were 100% accurate, which is unlikely. For example, a cross
wind affects an 850lb 12" shell less than a 350lb 9.2" shell, so there'd be dispersion by calibre. There will be lots of other things altering
the predicted behaviour of the gun, such as the guns having different shell trajectories for the same range, so they'd experience different atmospheric
conditions. Not to mention barrel wear. Even with guns of nominally identical design, there was considerable variation in performance, having mixed calibre
batteries just makes the problem harder.
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steevy |
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Posts: 124 ( 4-May-2008 16:28:56) |
The alternate batteries idea seems to me a good one.They called ships like Agamemnon and Danton Semi Dreadnaughts because of their heavy secondaries,it seems
to me such ships could have been very useful in a battleline,offensively at least.They had problems as far as speed(don't think they had turbines)and their
protection included alot of thinner armor(to protect against smothering at short ranges they were designed to fight at).They also seemed to be more vulnerable
to underwater damage(maybe because of smaller beam and total size?).The British had the luxury of using an all Dreadnaught fleet in WW1 because they had so
many.The Germans didn't builds Semi Drednaught types.I think the French used their's as an integral part of the battle fleet but they didn't get to
use them.Too bad the Italians stiffed the Central powers....hehe
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Lionage |
Late pre-dreds vs early dreadnoughts | ||
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Posts: 10 ( 4-May-2008 23:56:49) |
As a rule, pre-dreds were not turbine powered, although a few (Danton, Satsuma) were. Mind you, several of the early dreadnoughts were reciprocating
engine powered, such as the Nassau and South Carolina and slower than turbine powered pre-dreds. Remember though, these later pre-dreds were
completed up to four years after the Dreadnought.
The broadsides of the largest pre-dreds (Aki and Satsuma) was 4x12", 6x10", which is less than that of the Dreadnought or South Dakota. Taking a 12" shell as 850lb and a 10" as 500lb, the Aki's broadside is 6,400lb. The Dreadnought's is 6,800lb. Not much in total weight (about 7% more) but the benefits of being single calibre mean she's more accurate at longer ranges, and likely to hurt the Aki first. The Dreadnought only carries five turrets to the Aki's eight, resulting in a better protected ship for the same weight. The rate of fire of the 10" guns is not faster enough than the 12" guns to make much difference. The South Dakota is even more efficiently designed with only four turrets, even if she couldn't fire both her front (or rear) turrets directly ahead (or astern). I'd take her to beat the Aki under good visibility 8-9 times out of 10. |
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PhilJD |
Dreadnought design process | ||
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Posts: 619 ( 6-May-2008 14:49:18) |
part of the Dreadnought design process looked at using purely 6" guns en masse as that was considered by many to be an excelent calibre of gun due to the
rate of fire - 'smother the b@#&ards'.
However, the 12" guns selected proved (in theoretical terms) to be able to put more mass of shell on target at the mid-long ranges envisaged in battleship/battleship combats, hence the selection of 12"ers. The 9.2" proved to be between the performance of those (no surprise there!). The articles I've seen for the actual performance of the 9.2" suggest that they did not perform as well as expectations though, so moving to 12" was more of a better choice.
Regards
Phil
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