Scharnhorst vs Alaska

[parsifal]

US radar was so clear it could observe the fall of shot. The turret azimuth and bearing was controlled from the director, and this in turn obtained its data from radar fixes.

Radar assisted fire control, from 1943 onward was vastly superior to optical fire control, even in clear weather. Fall of shot was often not observed accurately under visual conditions, and the stereoscopic system in use at the time had the same difficulties as the low definition radars

A Naval War College study performed during World War II estimated that an Iowa Class (BB-61) battleship firing with top spot against a target the size of the German battleship Bismarck would be expected to achieve the following hit percentages (when using the Mk 34 Director) .
Range Percentage hits against a broadside target Percentage hits against an end-on target Ratio
10,000 yards (9,144 m) 32.7 22.3 1.47:1
20,000 yards (18,288 m) 10.5 4.1 2.56:1
30,000 yards (27,432 m) 2.7 1.4 1.92:1

An image of the Mk 34 director with mk 13 radar is attached

Sdmittedly this is a study for the 16" gun, but it does show just how good the USN FC systems had become by wars end

If these estimates were accurate, these ships were dangerously accurate in their fire which has to be attributed to radar direction in the Fire control arrangements. nothing else can explain its accuracy in my opinion. During Java Sea, for example there was something like 1200 rounds fired (from memory, at ranges of about 20000 yards. Only a handful of these rounds hit anything

 

[parsifal]

I fail to see how the 5.9s could be considered any better than the USN 5/38s. The 5.9s could only really be expected to do damage to the upper works, but with a ROF about 1/3 that of the USN 5/38, I think the range disadavantage of the 5/38 is more than compensated for by the high ROF.

 

[Glider]

The Alaska's speed advantage is of little use once battle has been joined unless she wants to keep the range long or run away.
The use of radar ranging in WW2 is little better than optical ranging in clear weather, at night or poor visibility certainly but not in clear weather. The accuracy of the German optical rangfinders at long range was proven in almost every action and radar is very vulnerable to damage once action is joined.
5.9 in guns have a clear advantage to the 5in when firing at ships. They have a longer range, a bigger shell and an improved chance of doing damage to the upperworks.
Remember if you throw in the 5in then the Scharnhorst can include the 4.1 in. If you want to get really fussy the Scharnhorst also had some torpedo tubes but that is getting a little silly.

 

[vikingBerserker]

I thought the 4.1's were AA guns?

 

[renrich]

Why would not the Alaska try to keep the range open to the point were her guns were most effective and the Scharnhorst's were least effective, just like the British BCs did with the original Scharnhorst?

 

[parsifal]

Glider, you keep saying that radar assisted FC was no better than optical in wwii, but the circumstantial evidence does not support that. Why would the USN undertake a study that suggests a far higher level of accuracy when using radar, over using optical guidance, even in clear weather.

I participated in gunnery training excercises in the '70s in Battle and Daring class DDs, which whilst modernized, were still very much wwii era technologies. I was not a gunery officer, but when we turned the radars off, our shooting accuracy slumped badly. These were still hand worked turrets remember....and they were also laid by hand as well, so I think the correlation to wartime experience is pretty close

So, what is your background information or experience for saying that optical gunlaying and FC is as good as radar directed gunfire????

 

[parsifal]

Why would not the Alaska try to keep the range open to the point were her guns were most effective and the Scharnhorst's were least effective, just like the British BCs did with the original Scharnhorst?

The AP capabilities of the 12/50 were as follows, using the 1140 lb Mk 18 AP shell ( these are straight cut and pastes from Lundstroms site)

Armor Penetration using 1,140 lbs. (517.093 kg) AP Mark 18 Shell
.
Range Side Armor Deck Armor Striking Velocity Angle of Fall
0 yards (0 m) 24.48" (622 mm) --- 2,500 fps (762 mps) 0.0
5,000 yards (4,572 m) 21.34" (542 mm) 0.51" (13 mm) 2,215 fps (675 mps) 2.6
10,000 yards (9,144 m) 18.23" (463 mm) 1.26" (32 mm) 1,948 fps (594 mps) 6.0
15,000 yards (13,716 m) 15.56" (395 mm) 2.14" (54 mm) 1,745 fps (532 mps) 11.0
20,000 yards (18,288 m) 12.73" (323 mm) 3.02" (77 mm) 1,550 fps (472 mps) 17.5
25,000 yards (22,860 m) 10.52" (267 mm) 4.02" (102 mm) 1,435 fps (437 mps) 25.3
30,000 yards (27,432 m) 9.08" (231 mm) 5.11" (130 mm) 1,400 fps (427 mps) 32.8
35,000 yards (32,004 m) 7.35" (187 mm) 7.18" (182 mm) 1,427 fps (437 mps) 44.5
Note: The above information is from "Battleships: United States Battleships 1935-1992" by Garzke and Dulin and is based upon the USN Empirical Formula for Armor Penetration. These values are in substantial agreement with armor penetration curves published in 1942.


The SKC 34 had the following characteristics (have previously posted this stuff)

Armor Penetration with 727.5 lbs. (330 kg) APC L4,4 Shell
.
Range Side Armor Deck Armor
0 yards (0 m) 23.79" (604 mm) ---
8,640 yards (7,900 m) 18.09" (460 mm) 0.76" (19 mm)
16,514 yards (15,100 m) 13.18" (335 mm) 1.63" (41 mm)
20,013 yards (18,288 m) 11.47" (291 mm) 1.87" (48 mm)
30,000 yards (27,432 m) 8.08" (205 mm) 2.99" (76 mm)
Note: The above information is from "Battleships: Axis and Neutral Battleships in World War Two" for a muzzle velocity of 2,920 fps (890 mps) and is based upon the USN Empirical Formula for Armor Penetration.

.
Range Side Armor Deck Armor
10,936 yards (10,000 m) 13.70" (348 mm) ---
16,404 yards (15,000 m) 11.02" (280 mm) ---
21,872 yards (20,000 m) 8.86" (225 mm) ---
27,340 yards (25,000 m) 7.64" (194 mm) ---
Note: The above information is from "German Capital Ships of World War Two." The data is based upon the pre-war Krupp test shoots on their range in Meppen with L/4,4 APC projectiles using RPC/32 propellant against KC-type armor at an impact angle of 70 degrees. It should be noted that RPC/32 propellant was replaced by the more powerful RPC/38 type which was the only propellant used in World War II.

I agree with you basic supposition, but cannot see any particulalr range that the 12/50 enjoys such a clear advantage.

If the US ship wanted to get its 5/38s into action, it would need to reduce the range to under 20000 yards. Even then the accuracy of both the 5/38s and the German 15/skc/28s due to the elevations needed in the guns would be very low.

My gut feeling would be to reduce the range to about 18000 yards, and then hold it from there.....

 

[DonL]

To close the range for Alaska would be her death.

SH would be save under 18000m. No 12 inch shell ( 517kg) will go through the main belt with 350mm and the lower main deck with 105mm. And optic shooting gets better with every meter of shorter distance and the guns of SH would be more powerfull to the 220mm inclined belt too.

 

[Glider]

Glider, you keep saying that radar assisted FC was no better than optical in wwii, but the circumstantial evidence does not support that. Why would the USN undertake a study that suggests a far higher level of accuracy when using radar, over using optical guidance, even in clear weather.

I participated in gunnery training excercises in the '70s in Battle and Daring class DDs, which whilst modernized, were still very much wwii era technologies. I was not a gunery officer, but when we turned the radars off, our shooting accuracy slumped badly. These were still hand worked turrets remember....and they were also laid by hand as well, so I think the correlation to wartime experience is pretty close

So, what is your background information or experience for saying that optical gunlaying and FC is as good as radar directed gunfire????

The Scharnhorst hit the Glorious a fast moving, evading target about the same size as a BB at a range of about 26,500 yards with her third salvo. By any standards first class shooting with or without radar ranging. Any BB would do well to match that whatever their equipment.

Its also worth noting that the Ardent was hit with the first 5.9in broadside.

As for my experience I served on HMS Tiger the last 6in cruiser in the RN during firing tests. She normally hit the target with the second or third ranging shell which is not very different from the Scharnhorst. The difference of course was that once whe had the range the ROF destroyed the target in double quick time.
An aside but the Tiger hit the air target (and I do mean hit, not close enough), with the second shell so her radar ranging was at the time, state of the art.

 

[parsifal]

Your experience is very good, and great shooting by the sounds of it. However, I would point out that Glorious was steaming straight and at constant speed at the time she was hit, as she attempted to range a strike against her two pursuers.

"Gneisenau and Scharnhorst were at 69°00'N, 03°10'E steaming at 19 knots on course 330° when smoke was sighted on the eastern horizon at 1546. Steam was raised for full speed, and course altered to close the enemy. By 1636 Gneisenau was making 30.5 knots and Scharnhorst, experiencing boiler trouble, was making 29. Scharnhorst, initially in the leading position, opened fire on Glorious at 1632, range 28600 yards (26150 meters). Gneisenau opened fire at 1646. Gneisenau's slightly superior speed allowed her to slowly overhaul the Scharnhorst during the action, until she had put the Scharnhorst some 22 cables (4850 meters) on her port quarter. The two ships maintained these relative positions until near the end of the engagement, when Gneisenau reduced speed.

In accordance with instructions from Glorious. Ardent closed the enemy ships flashing a challenge on her searchlight. She was taken under fire by Gneisenau at 1627 and by Scharnhorst at 1630 at a range of about 16000 yards (14600 meters). Ardent withdrew, firing torpedoes, one of which was seen to pass close ahead of the Scharnhorst. Both destroyers made smoke to screen the Glorious. This smoke was effective enough to force the Germans to cease fire from about 1658 to 1720. Ardent made one hit on Scharnhorst with her 4.7-inch guns, but was extensively hit by return fire from the 5.9-inch secondary armament of the battlecruisers, and sank at about 1725.

Glorious received her first hit at 1638 from Scharnhorst's third salvo. The 283mm shell penetrated the flightdeck and burst in the upper hangar starting a large fire.4 Splinters pierced a boiler casing and smoke entered air intakes. This caused a temporary drop in steam pressure from two boilers, but pressure was built up again as the smoke cleared. Further hits were obtained after 1720 as the carrier once again became visible through the smoke of the screening destroyers. At 1656, just before the Germans ceased fire due to screening smoke, a hit on the homing beacon wrecked the bridge, killing the captain and almost all of the bridge personnel. The Executive Officer assumed command of the ship. About 1720 a hit in the center engine room shook the whole ship, which thereafter began to lose speed, develop a starboard list, and commence a slow circle to port. The Germans ceased fire at about 1740, and Glorious sank at about 1810."

Assuming that Gneisenau was shooting at approximately the same rate, it would seem that the Germans expended 6 full salvoes before registering a single hit. This was against a target that until that point was not zig zagging. Still great shooting, but hardly of the same standards as your analysis suggests. Compared to the radar assisted gunnery of the Iowas, this is just average.

And for every action where their was this above average shooting, there are 6 or 7 instances where the shooting is poor when relying on visual FC. I still dont think it is nearly as accurate as late war Radar assisted FC.

 

[parsifal]

To close the range for Alaska would be her death.

SH would be save under 18000m. No 12 inch shell ( 517kg) will go through the main belt with 350mm and the lower main deck with 105mm. And optic shooting gets better with every meter of shorter distance and the guns of SH would be more powerfull to the 220mm inclined belt too.

So you dont think the ability to place a an 1140 lb shell, capable at that range (18000 m) with armour penetration of about 14 inches is going to hurt the German Battlecruiser.

By comparison the the German ship can penetrate about 8.8 inches of plate, which is not quite enough to penetrate the main belt of the Alaska, once the angle of the hit is taken into account, as well as the STS bulkheads on which the Alaskas belt is hung

I think you should check the gunnery tables again.

I do agree that optic shooting gets better as the range reduces, but so too does radar assisted FC. At 18000 metres the Alaska could use her 5 inche guns with a firing cysle on average threee time the rate of the 5.9 inch guns on Scharnhorst.

 

[Shortround6]

the use of secondary guns at ranges proposed is rather silly.

At these extreme ranges the angle of elevation is 35-40 degress or better and the angle of decent is going to be about 60 degrees meaning the trajectory is going to look like a mortar shot. Time of flight is going to much longer than the Main guns to the same range.

Some Navies did not like the secondary guns firing during long range main battery shoots because of gun gas/smoke drifting across main gun director sight lines. Even if the gas/smoke doesn't totally obscure the target even a thin smoke can make use of the optical range finders more difficult. As can the minor shell splashes. While the director peaple can probably tell the difference between a 6" splash and a 11" splash trying to get clear image of the target with several 6" splashes obscuring it doesn't help.

Use of secondary guns against a second target is much more useful. You still have the gun gas problem but the secondary splash problem goes away. You also keep the secondary target/s from having an unopposed target shoot which should lower their hit potential even if you don't score any hits.

 

[parsifal]

Shortround, I do basically agree with you, though your angles for impact are a bit overstated. The angles for the 5.9s at range 16K is 11.5 with an angle of fall of 23.5 degrees. At range 21K the angle of fall is 42 degrees. This is easily plunging fire, though not quite "mortar fire as you suggest.

Nevertheless, the Germans found the use of the secondary armament in this battle as interfering with the accuracy of the main armament and ceased using it for a bout 20 minutes after 1700, to facilitate the rapid sinking of the primary target. in other words, the secondary armement was found to be a hindrance overall....though essential to keep the DDs busy.

One other thing I found about this battle.....dealing with the alleged accuracy of fire from the German optical fc arrangements. though indeed they achieved their first hit after only three salvoes, overall, until the Glorious was stopped and reduced to a sitting target, the Germans had expended 387 rounds of 28 cm ammunition from the two ships, to achieve something like 4 hits on the Glorious up to that time. According to the German records the average engagement range of the primary target4 was 24000 yds. The overall shooting accuracy of the german ships using optical means, under ideal conditions was 1.03%. At that same range, the USN reckoned that the Iowa could achieve a firing accuracy against a Bismarck sized target, broadside on, of 10.5%, or 4.5% in an end on situation. Since for most of the glorious engagement, the silhouette of the British ship was somewhere in between, the average number of hits if the fire had been radar controled would have been about 7% (I estimate). In other words, the visula means used by the germans is going to be somewhere between 10 and 25% as accurate as radar assit3ed gunnery, even under ideal conditions.

 

[Glider]

At the end of the day we agree that the Scharhorst hit the carrier with the third salvo. Which was similar to the Tiger using radar fire control. The Alaska would not be zig zagging as she would be firing back so that equals that out. I believe that the difference would not be much, not that optical was as good, and what evidence we have supports that. Radar is vulnerable to damage, that I believe cannot be questioned and once hits are registered its in the lap of the gods as to the final result. If a splinter from an early hit takes out the Alaska radar F/C then all bets are off.

The comments about the accuracy of the firing tends to ignore that the RN used smoke screens to a considerable degree and this obviously hinders optical F/C. I would however agree that the Gneisenau was less accurate than the Scharnhorst which shows what a difference the crew makes.

I am always cautious of theoretical projections of accuracy, if you believe them guided missiles would never miss and I have never seen theoretical projections continue into the real world.

 

[parsifal]

why cant the alaska or the scharnhorst change course and speed during the battle. In any event if you are right, then if one cant manouvre, then surely both cant, and therefore the ability to manouvre or not manouvre will not affect the overall comparison between radar assisted and visual fire

we now have a set of numbers for ammunition expended to hits achieved for optical fire. Now perhaps we should try to get a representative sample of ammunition expended to hits achieved for radar assisted gunnery, and see what the difference might be

During the battle of North Cape, Scharnhorst was targeted by no fewer than 55 torpedoes, 11 of which probably found their mark. More than 2000 shells were fired at her: 446 x 356 mm (14-inch) from Duke of York, 161 x 203 mm (8-inch) from Norfolk, 874 x 152 mm (6-inch) from Jamaica, Sheffield and Belfast, 686 x 133 mm (5.2-inch) from Duke of York and 126 x 120 mm (4.7-inch) from the destroyers.

Of the 446 14 in fired, no fewer than 18 found their mark, at an average engagement range of 18000 metres ( for the battleships). Remember, this battle was fought in terrible conditions, sall things being equal, the british ship should actually have a lower hitting average. But the reverse effect is observed....why??? The ratio of hits achieved by the radar assisted gunnery to ammunition expended is 4.03%, or more than 4 times that achieved by the Scharnhorst/Gneisenau gunnery teams. The range was 25% less, but the weather and sea state much worse.

Why would the british gunnery be four times more accurate than the Scharnhosts, when all except two of the variables are comparable. Range and radar......And I think the decreased range of the North cape battle is more than offset by the poor weather conditions. That leaves only one variable that is influencing the hit rate....radar

 

[Shortround6]

Shortround, I do basically agree with you, though your angles for impact are a bit overstated. The angles for the 5.9s at range 16K is 11.5 with an angle of fall of 23.5 degrees. At range 21K the angle of fall is 42 degrees. This is easily plunging fire, though not quite "mortar fire as you suggest.

they may be a bit overstated but I think you have given the angles for the 15cm SKC/25 guns from the light cruisers with the triple turrets. these used a much larger charge to get another 85m/s vellocity. Elevations in Campbell's for the Sharnhorsts guns are 22,000 m/35^ and 23,000m/40^ vrs 25,000m/36.3^ and 25,700m/40^ for the cruiser guns.
Somebody did mention 20,000yds for the 15cm guns to become effective.

Ranges for the American 5"/38 are given as 14,532m/27^, 15,923m/35^ and 16,640m/45^. or 10 degrees of elevation for the last 717meters of range.

The page layout in my copy of Campbell's is bit confusing in that it does show a picture of the Graf Spee below the Description of the Cruiser guns with the 15cm SKC/28 description on the next page.

 

[Glider]

why cant the alaska or the scharnhorst change course and speed during the battle. In any event if you are right, then if one cant manouvre, then surely both cant, and therefore the ability to manouvre or not manouvre will not affect the overall comparison between radar assisted and visual fire

I agree with the final section. The point I was trying to make was that zig zagging is a lot different to making a deliberate manouvre during combat.

we now have a set of numbers for ammunition expended to hits achieved for optical fire. Now perhaps we should try to get a representative sample of ammunition expended to hits achieved for radar assisted gunnery, and see what the difference might be

During the battle of North Cape, Scharnhorst was targeted by no fewer than 55 torpedoes, 11 of which probably found their mark. More than 2000 shells were fired at her: 446 x 356 mm (14-inch) from Duke of York, 161 x 203 mm (8-inch) from Norfolk, 874 x 152 mm (6-inch) from Jamaica, Sheffield and Belfast, 686 x 133 mm (5.2-inch) from Duke of York and 126 x 120 mm (4.7-inch) from the destroyers.

Of the 446 14 in fired, no fewer than 18 found their mark, at an average engagement range of 18000 metres ( for the battleships).

This is interesting stuff but of little assistance. We know how many shells were fired at her but have no accurate idea as to how many hit. As to the average range of 18,000 yards I doubt that. The DOY started firing at 11,000 yards. about 30 minutes later the DOY was still at 13,000 yards. 20 minutes later the range was 16,500 yards. 20 minutes later the range was about 18,000 yards. 24 minutes later the range was 19,500 and the DOY ceased fire. The DOY opened fire again at a range of 9,500 yards and the range closed to 7,500 yards. I don't have the time to do the sums but its a lot less that 18,000.

Remember, this battle was fought in terrible conditions, sall things being equal, the british ship should actually have a lower hitting average. But the reverse effect is observed....why??? The ratio of hits achieved by the radar assisted gunnery to ammunition expended is 4.03%, or more than 4 times that achieved by the Scharnhorst/Gneisenau gunnery teams. The range was 25% less, but the weather and sea state much worse.

I think this point is covered by the earlier reply mainly the range was about 50%.

Why would the british gunnery be four times more accurate than the Scharnhosts, when all except two of the variables are comparable. Range and radar......And I think the decreased range of the North cape battle is more than offset by the poor weather conditions. That leaves only one variable that is influencing the hit rate....radar

You keep including the two ships together in your calcs but the Scharnhorst is the vessel in question and she was more accurate than her sister ship. That has been admitted.
The question you keep avoiding is why would the Alaska be more accurate than the Tiger a later ship with more up to date radar and one that I know from firing trials was a very accurate ship?

 

[Juha]

Hello Glider
on the other hand neither Scharnhorst nor Gneisenau were particulately accurate during the action against Renown only 2 months before the sinking of Glorious, Ardent and Acasta, and Scharnhorst fire was reported as inaccurate during Spitzberg raid in Sept 43, but that was some 2½ years later.

Juha

 

[Glider]

Juha
Your right I cannot deny it. Can I claim a bad day at the office?

 

[Juha]

Hello Glider
Of course. All what I tried to say was that there tended to be variations in human actions, at least most of us have better and worse days . And on 9 Apr 40 conditions were really awful, maybe even the fact that SH GN were under 15in fire had some slight effect. But the weather was surely the main factor to gunnery difficulties. And it seemd that Gneisenau got the both sure hits on Renown, nobody knows when the possible 3rd hit on the top of one funnel happened.

Juha