Practical ranges

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paul.mercer
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Practical ranges

Postby paul.mercer » Tue May 01, 2012 7:59 pm

Gentlemen,
A lot has been said about maximun ranges of big guns (15" or 16"), as well as the use of radar in range finding, in your opinions given the range finding equipment available up tp the end of WW2 what is a practical range for those guns to obtain regular hits, using either 8 or 9 guns (depending on the ship), say in a moderate Atlantic seaway?

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Re: Practical ranges

Postby alecsandros » Fri May 04, 2012 5:14 pm

I would say it depends :)

On a good clear day, with reliable information (say, from a float plane hovering 50km away), 2 modern battleships could probably hope to plaster each other consistently at 22km, maybe 25.

If the weather wasn't good enough to allow optical target identification, or if information was insufficient, the battle woudl probably not take place, until 10-15km.

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Re: Practical ranges

Postby Dave Saxton » Sat May 05, 2012 7:50 pm

The Scharnhorst spotted the Glorious and identified it as a carrier when it was still 42km away. Adm. Marschall ordered the radars switched on to help range the target. They waited until the Glorious was within radar range before he gave the okay to open fire at 26km range (28,500 yards). I suspect Marschall wanted to be able to use a more precise range measurement to make better use of the ammunition. They did not catapult observation planes.

The British opened fire at 25,000 yards (22.8km) at Denmark ST and again at the final battle against Bismarck despite rough sea conditions and optics contending with spray.

Bismarck and Prince of Wales traded a few half hearted salvoes at about 30,000 meters but neither obtained hits. Spotting the fall of shot was difficult for Bismarck because of the glare off the sea surface from its position, and it was just beyond the range of its foretop radar assuming it was operational.

BB59 opened fire at 16,000 yards at Casablanca and ceased fire once the range opened up to 27,000 yards (~25km). It reopened fire at 27,000 yards as the range came back down later.

The Italians and the British sometimes traded salvoes at beyond 25,000 yards but only Warspite obtained a hit.

Yamato, Kongo, and Nagato, opened fire off Samar at 31km (34,000 yards).

Generally it was prefered to be able to identify the target visually, but to range the target if possible via electronic means if available. Radar is about 10 fold more accurate than optics for range taking at long ranges. Nonetheless, optical bearing was almost always used with or without radar capable of good bearing accuracy, as long the target could be seen. In other words radar ranging combined with optical bearing. This was still the prefered method late war by the USN.

Another thing was spotting the fall of shot. This would normally be done visually until the range became so great that the target's hull was down and overs and shorts could no longer be easily determined. Then radar would could be used to spot if it was capable of picking up the splashes at those ranges. Duke of York, shooting in the dark, had to quit shooting once the range reached 19km because it's radar could no longer spot the fall of shot and it was beyond the range of visual observation via star shell.

So max practical range late war in day light could be defined by the effective range that radar could range the target and spot the fall of shot. However, radar doesn't change the low probability of scoring hits at such ranges due to ballistic reasons. In most cases I'd say the max practical range in excellent conditions, late war, was about 30km (33,000 yards) for all combatants. Shooting range may exceed that if there's no reason to not waste ammunition
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Re: Practical ranges

Postby alecsandros » Sun May 06, 2012 4:01 pm

... And Oldendorf's battleships opened at 22000 yards, or 20km, during the night, with radar-ranged salvos, scoring hits in the first salvos.

Above 25km, depending on the gun, either dispersion is to large, or the angle of fall becomes to steep, and danger space is to small to consistently hit an opponent.
MOreover, the time of flight of the shell is so long that a fast enemy can change position and heading quite easily in the 45-60 seconds necessary for the shell to strike.

Maybe straddling, yes, but hits - very difficult...

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Re: Practical ranges

Postby Dave Saxton » Sun May 06, 2012 7:11 pm

alecsandros wrote:... Above 25km, depending on the gun, either dispersion is to large, or the angle of fall becomes to steep, and danger space is to small to consistently hit an opponent.
MOreover, the time of flight of the shell is so long that a fast enemy can change position and heading quite easily in the 45-60 seconds necessary for the shell to strike....



It's probably not by tactical circumstances alone that BB59 did its shooting within that radius at Casablanca. The BB to BB range of its FC radars was also about 27,000 yards but since the radars were knocked out by gunfire shock right at the start of action that probably wasn't the reason. One notes that the 1945 BB59 gunnery doctrine reads 27,000 yards as extreme range.
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Re: Practical ranges

Postby alecsandros » Mon May 07, 2012 5:48 am

Dave Saxton wrote:It's probably not by tactical circumstances alone that BB59 did its shooting within that radius at Casablanca. The BB to BB range of its FC radars was also about 27,000 yards but since the radars were knocked out by gunfire shock right at the start of action that probably wasn't the reason. One notes that the 1945 BB59 gunnery doctrine reads 27,000 yards as extreme range.


Hmm, haven't thought about this before. It's very likely Massachussets stopped firing over 25km because it would have been a waste of ammo.

What's also interesting is that in both the longest gunfire hits (Scharnhorst in 1940 and Warspite in 1941), a lot more shells were expended, but only a few hits obtained. Warspite continued firing against Giulio Caesare after the spectacular hit, but it didn't hit anything else.

So even at 25km, hitting a moving target had a low probability...

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Re: Practical ranges

Postby Dave Saxton » Mon May 07, 2012 2:16 pm

Looking up some data, I'm surprized to learn that Scharnhorst only fired 212 28cm shells in the entire June 1940 action and Gneisenau less. Not all of the 28cm shells were fired at the carrier. Bismarck fired 93 38cm shells at Denmark St. in less elapsed shooting time. The total time spent shooting at the carrier wasn't as long as the elapsed time between the time when SH opened fire and when the carrier sank. The shooting was interupted several times.

Gneisenau opened fire first on Ardent which had closed to 15,000 meters five minutes before SH opened fire on the distant carrier. GN hit the destroyer with its first salvo (15cm guns IIRC). Then SH opened fire at Ardent with 15cm as well.

A range taker (and later an trained radar operator), now an American citizen, described his memories of the action:

Frank spotted with the optics the Glorious on the horizon and let the bridge know. (Glorious) Airplane carrier and destroyers… The glorious was protected by 2 destroyers….once the English found out enemy (the Scharnhorst) was near the destroyers blew dark black smoke to hide the Glorious …
The Scharnhorst shot 1 far, 1 low, 1 in the middle of the runway… runway on fire….


So SH was using a bracketing procedure and its firing solution was spot on. Had it shot to straddle with the first salvo it may have scored a hit. But with cold guns the first shots usually don't range correctly. Because of that fact the first salvo is often used to check bearing track and as part of a bracketing procedure. SH was initially shooting very deliberately; spending 6 minutes to fire the opening salvoes. Just as it had began to score on the the carrier it turned away 30* when hydrophones picked up torpedoes fired by Ardent. I don't know if it ceased fire on the carrier or continued to shoot at Glorious during the maneuvers.

By then GN was over taking SH because SH was making 29 knots and GN 31 knots, and GN took up shooting at the carrier (still exceeding 20km range) and SH took up shooting at the DDs. GN only fired at Glorious for a few minutes (scoring hits on the bridge and taking out the radioes) when the Germans ceased fire for 15 minutes on the carrier because of the heavy smoke. After the 15 minutes, both SH and GN opened fire on the carrier with GN scoring quickly with the hits penetrating the boiler rooms. The Glorious sank an 1/2 hour after the last German shots fired at it.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Practical ranges

Postby alecsandros » Mon May 07, 2012 3:26 pm

A, nice info
Still, it appears that only a 3 or 4 hits were made > 20km, the others coming after the twins had closed the range quite a bit, at 15km or so.

IIRC, Hoffman was criticised on return for wasting expensive ammunition...

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Re: Practical ranges

Postby Dave Saxton » Mon May 07, 2012 5:41 pm

Actually most of the shooting against the carrier was probably beyond 20km (~22,000 yards). When SH first opened fire, Glorious was still approaching head on with a combined closure rate of ~60knots. However once SH fired, Glorious began a 180* turn completed in four minutes and was soon making full speed again until GN later demolished its boiler rooms. The Germans didn't keep firing at Glorious much longer after that.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Practical ranges

Postby alecsandros » Tue May 08, 2012 4:19 pm

Well, I know of 3 definite shell hits in the first hour:
1 - forward flight deck (4:32)
2 - above the bridge (4:58)
3 - engine room (5:20)

Most of the shooting was done against Glorious, probably over 200 x 11" shells by the 2 raiders, and possibly 300...

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Re: Practical ranges

Postby Dave Saxton » Wed May 09, 2012 3:59 am

Those are the pivitol hits, but I doubt they were the only ones. An old BC hull should take more than that, or the 28cm shells are very effective.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Practical ranges

Postby lwd » Wed Jun 20, 2012 7:06 pm

Glorious was hardly built on a BC hull. While origianlly planned to cary 4 15" guns she wasn't armored like a battle cruiser indeed they weren't called large light cruisers without reason.

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Re: Practical ranges

Postby Neoconshooter » Tue Dec 04, 2012 5:50 am

alecsandros wrote:... And Oldendorf's battleships opened at 22000 yards, or 20km, during the night, with radar-ranged salvos, scoring hits in the first salvos.

Above 25km, depending on the gun, either dispersion is to large, or the angle of fall becomes to steep, and danger space is to small to consistently hit an opponent.
MOreover, the time of flight of the shell is so long that a fast enemy can change position and heading quite easily in the 45-60 seconds necessary for the shell to strike.This is not true. It takes so long for a BB to change direction that it would have had to have had the rudder hard over for 30-60 seconds before the shell was fired to change the ships course more than a few degrees and few dozens of meters.

Maybe straddling, yes, but hits - very difficult...

Late war after much fiddling, the average/maximum, depending on who said what, spread of salvo for the Iowa and her sisters was 269 yards long at 25,000 yards. Given late war Radar and FCS, such a salvo would have a >16% of any given shell hitting a broad side target 35 M wide and 10 high. If the target was nose, or stern on, the width of such salvo would be half that 269 yards, or 135 yards wide, thus a the typical ~7,000 M^2 target area BB would give a larger, 25% chance to be hit. So with that most excellent FCS and gun/system accuracy, it would be entirely possible for Iowa and her sisters to take out Bismarck or Tirpitz at >39,700 M, given the Strategic Imperative to do so regardless of Munition expenditure!

Given the low shell weight/SD, very high velocity and low elevation and subsequent angle of "Fall of shot" Iowa and her sisters might be immune to Bismarck and Tirpitz return fire until such time as the range has shortened considerably. Given the USN's insistence on superior maneuverability and speed, it is doubtful that either German ship could either close the range, or escape.

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Re: Practical ranges

Postby Neoconshooter » Tue Dec 04, 2012 6:04 am

alecsandros wrote:A, nice info
Still, it appears that only a 3 or 4 hits were made > 20km, the others coming after the twins had closed the range quite a bit, at 15km or so.

IIRC, Hoffman was criticised on return for wasting expensive ammunition...

At long range, it only takes three or four hits to sink most ships. Plunging fire and less thick deck armor combined with the lack of armored bottom to stop flooding results in easy kills. See;
http://web.archive.org/web/200702052335 ... 50_mk7.htm

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Re: Practical ranges

Postby Thorsten Wahl » Tue Dec 04, 2012 7:15 am

At long range, it only takes three or four hits to sink most ships

any sample available?
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