WWII Battlecruiser matchup

[Ol Paint]

Originally posted by hojutsuka:

Douglas,

 

Can you tell me where in Friedman (what book and page) you found that?  I did a quick scan in my "U.S. Cruisers" and found nothing about a 205,000shp Essex plant.  The Essex plant is in fact 150,000shp as designed, and IMHO is almost certainly the basis for the Alaska class propulsion.  Since the Alaska used geared turbines, there is no way that BuEng would have gone for 5x30,000shp units (5 shafts? no way!) especially when there was a 150,000shp system in full production.  In fact, a look at the data in Appendix C of "U.S. Cruisers" shows that the Alaska class had 8 boilers, i.e. could not be 5x30,000shp.  Incidently, the Essex plant is actually based on a pair of 75,000shp plants originally developed for the Atlanta class light cruisers (Friedman, "U.S. Aircraft Carriers", page 140).

 

Hojutsuka

 

US Cruisers Page 293.

On 18 November 1939 the General Board recommended continued consideration of CA2, and on 22 November it passed tentative characteristics to C&R.  They were essentially those advanced in April 1938, with the major exception that speed was to be 33 rather than 35 knots; studies of the Essex-class carrier design had shown that the 205,000 SHP required for the former could not be accommodated without giving up all underwater protection--an important issue in a ship operating independently.

I did look at the characteristics for Alaska, which is why I discounted the use of the 30,000shp units. Now, it looks like I misinterpreted the above passage as reading that the 205,000shp was installed in the Essex, instead of simply being considered to drive the carrier faster, but discarded. I didn't cross-check the Essex characteristics. Sorry about that.

 

Douglas

[Tiornu]

I just noticed a reference in the current Warship International to another anti-shipping weapon with a hollow charge, the British 5600-lb Capital Ship Bomb. Only four of these were made, and only three were used in action. All missed their targets. Like the German coast defense rocket, this would have a steep trajectory and no spin.

[Guest Sargent]

Originally posted by Tiornu:

I just noticed a reference in the current Warship International to another anti-shipping weapon with a hollow charge, the British 5600-lb Capital Ship Bomb. Only four of these were made, and only three were used in action. All missed their targets. Like the German coast defense rocket, this would have a steep trajectory and no spin.

 

 

 

And either a low striking velocity or enough stand-off that charge deformation wouldn't be a factor.

 

Another nifty little British Secret Weapon was the "B Bomb." Developed pre-war, it was designed to miss and then bob up under the targent ship for a mining effect on the bottom. All you had to was put the B Bomb exactly 200 feet dead ahead of the target.

 

Demmed clevah, those chaps....

[Mobius]

Originally posted by Tiornu:

We have a set of penetration tables posted at http://www.geocities.com/kop_mic/ 

Tiornu, is that your site? I've visted it before.

I was wondering how to get the vector penetration.

That way I can try to work out penetration of complex armor schemes.

[Durandal]

Originally posted by Tiornu:

Yes, at Casablanca one 16in dud rattled its way along the top of the armor deck. Damage wasn't extensive, but it did kill the ship's XO. The other dud disabled JB's only turret by deforming the armor and shorting out the electrical training gear.

 

 

I am entering the thread late but not too late

 

This is not by a direct hit on the ship but on the dock at 7h45 the projection of stones are doing some damages. At 8H06 a direct hit on turret 1 (the only one almost finished) locked the turret. for several hours. at 8H10 a direct hit on the rear deck is perforating all armored decks and explode in the water ballast. for the US the Jean Bart is out of service. but the day after the BB is firing again on the Augusta.

The Jean bart is then bombed by 8 Rangers's bombers (dauntless?) equiped with 500kb Bombs.

2 hits 14H58 day+1

the first hit is making a big hole in the front deck destroying parts of the structures. the second bomb hit the rear deack destroying 30meters radius of structures under the armored deck. the Jean bart is sinking.

So this is not a hit by a 16" but by 2 500Kg bombs.

 

And imho their is nothing glorious to hit a non moving BB, not even finished btw.

[Durandal]

Originally posted by Dan Robertson:

Interesting because Scharnhorts and Gneisenau did actually meet Renown, but for some reason ran rather than fight her, even though there were two of them.

 

Another interesting match up that nearly happened was Hood verses Strasborg, which happend after Mers el Kebir. Strasborg was not hit by British fire, it set up a smoke screen and picked its way though the magnetic mines the the RN had laid accross the harbour enterance. It then ran to Toulon and avoided engagement by HMS Hood (also classed as a battlecruiser) because that had a engine fault.

 

That would have been a short engagement,provided it didn't go the way of Hood's later "stort engagement".

 

 

Le Strasbourg at the betrayal of Mers Elkebir avoiding engagement...

btw the hood is a 45000 tns BB and the Strasbourg a 23000 BC so again no glory.

[Tiornu]

"Tiornu, is that your site? I've visted it before.

I was wondering how to get the vector penetration.

That way I can try to work out penetration of complex armor schemes."

Yes, I guess you could consider me the "editor" of the tables. Rob Lundgren did all the hard work, though.

You cannot use that information to extrapolate more complex systems. What you would have to do would be to get the FACEHARD and M79APCLC programs--available for free download at http://www.navweaps.com/index_nathan/index_nathan.htm --and analyze the path of the shell through the armor system step by step. Anyone who has read Nathan's Bismarck essay has seen that sort of analysis.

[Tiornu]

Hood was 42,000 tons, and Strasbourg, 26,500 tons.

I'm not sure what glory has to do with anything.

[Guest Sargent]

Originally posted by Durandal:

The Jean bart is then bombed by 8 Rangers's bombers (dauntless?) equiped with 500kb Bombs.

 

Yes, Ranger's bombers were SBD "Dauntless."

[Guest aevans]

Originally posted by Tiornu:

Yes, I guess you could consider me the "editor" of the tables. Rob Lundgren did all the hard work, though.

You cannot use that information to extrapolate more complex systems. What you would have to do would be to get the FACEHARD and M79APCLC programs--available for free download at http://www.navweaps.com/index_nathan/index_nathan.htm  --and analyze the path of the shell through the armor system step by step. Anyone who has read Nathan's Bismarck essay has seen that sort of analysis.

 

Now here's an interesting question -- do armor piercing shells refract (i.e. change direction of travel) when passing through armor at non-normal angles?

 

(I wouldn't think so, but does anyone know for sure?)

[Guest Sargent]

Originally posted by aevans:

Now here's an interesting question -- do armor piercing shells refract (i.e. change direction of travel) when passing through armor at non-normal angles?

 

(I wouldn't think so, but does anyone know for sure?)

 

I don't know about large naval shells, but at tank gun sizes the shells that strike at an angle will tip until they are at 90 degrees from the surface and then bore through. Is this what you re looking for?

[Guest aevans]

Originally posted by Sargent:

I don't know about large naval shells, but at tank gun sizes the shells that strike at an angle will tip until they are at 90 degrees from the surface and then bore through. Is this what you re looking for?

 

Nope. I actually meant to ask if penetrating shells change course by a predictable number of degrees, not whether they yaw. (Though I am aware of this and am sure it plays a part in subsequent encounters with armored structures.)

[JOE BRENNAN]

Originally posted by Durandal:

This is not by a direct hit on the ship but on the dock at 7h45 the projection of stones are doing some damages. At 8H06 a direct hit on turret 1 (the only one almost finished)  locked the turret. for several hours. at 8H10 a direct hit on the rear deck is perforating all armored decks and explode in the water ballast. for the US the Jean Bart is out of service. but the day after the BB is firing again on the Augusta.

The Jean bart is then bombed by 8 Rangers's bombers (dauntless?) equiped with 500kb Bombs.

2 hits 14H58 day+1

the first hit is making a big hole in the front deck destroying parts of the structures. the second bomb hit the rear deack destroying 30meters radius of structures under the armored deck. the Jean bart is sinking.

So this is not a hit by a 16" but by 2 500Kg bombs.

 

This is not quite like regular case where one side thinks it hit X, but other's records say Y. USN Ordnance was able to survey the Jean Bart, and accounts of the 16" hits in US sources come from that report; I don't really see a reason to doubt it. As far as further damage from near misses, French sources may clarify those.

 

8 Nov 1942: the 2700lb 16" shells fell at 25 deg, 1520 fps calculated from the range of 25,000 yards. Hits were:

1) detonated in empty secondary battery magazine.

2) detonated below after control station, Ordnance concluded that a heavy nose fragment of this shell punching a hole in the bottom was the cause of the after flooding.

3) passed through the ship striking only the funnel and other light plating, then into the water.

4) glanced off No. 2 barbette, lost based plug and filler didn't detonate

5) richoted off No.1 turret losing based plug and filler, gouging armor on barbette jamming turret.

 

No.4 and 5 were recovered and examined.

 

When JB resumed firing 10 November, it was attacked by 9 SBD-3's of VS-41 from Ranger, carrying 1000# bombs with 1/100 sec fuzes. Two hit the JB, one fwd one aft and chewed up a lot of light structure.

 

The interesting point to me is what caused the ship to settle. The second 16" hit seems plausible because it did punch a hole in the bottom. But the other account suggests the ship didn't settle for a while. Maybe pumps held the flooding from the shell hit, but later failed because of the bomb hit.

 

forward

 

aft

 

Joe

[Tiornu]

Shells certainly do deflect and yaw after penetrating armor plates. The effects can be dramatic. During Savo Island, a shell struck one of the US cruisers in the ice cream machine and deflected deeper into the vitals. Weird, huh?

The change in direction caused by the penetration of armor is a key reason for the All or Nothing system. Just after WWI, the British set up a simulation of a plunging hit on Hood at about 25,000 yards--except this was Hood with her decks beefed up to 10 inches thick on three levels. The shell went straight through with lots of residual velocity while its angle of descent increased by 60%. When plates are parallel, they can actually increase penetration on subsequent levels.

[Tiornu]

Some disagreements between French and American sources arise from differing definitions of what a hit is. One shell struck the pier and caused damage to the hull. French sources list this as a hit, but not American sources. And there was another area of bulge damage that the French label as a hit. What I cannot reconcile are the differing accounts of the shells' descent angles. I think the French and Americans both had the same evidence to examine, but in one case, the descent angles they give are like 8deg off.

[Guest Sargent]

Originally posted by Tiornu:

During Savo Island, a shell struck one of the US cruisers in the ice cream machine and deflected deeper into the vitals. Weird, huh?

 

The shell was obviously lubricated by the ice cream. Now if we could just find an ice cream coating for shells that wasn't melted by the heat of firing...

[Jeff]

Originally posted by JOE BRENNAN:

forward

   

 

 

Interesting picture in that you can see the forward end of the armored box and the light construction from there forward.

[Scott Cunningham]

That shell wrecked the entire front end of the Jean Bart.

[JOE BRENNAN]

Originally posted by Scott Cunningham:

That shell wrecked the entire front end of the Jean Bart.

 

The visible damage fore and aft is from the bombs, .01 sec fuzed 1000# GP bombs.

 

Joe

[Tiornu]

JB's forward transverse bulkhead is just a couple meters forward of the barbette.

The most alarming aspect of this hit, as far as the French crew was concerned, must certainly have been its location, just above the wine storage compartment.

[Mobius]

Originally posted by Tiornu:

JB's forward transverse bulkhead is just a couple meters forward of the barbette.

The most alarming aspect of this hit, as far as the French crew was concerned, must certainly have been its location, just above the wine storage compartment.

 

The three most important ingredients in shell hits:

Location, location, location.

[Tiornu]

Good one!

[Durandal]

Originally posted by JOE BRENNAN:

This is not quite like regular case where one side thinks it hit X, but other's records say Y. USN Ordnance was able to survey the Jean Bart, and accounts of the 16" hits in US sources come from that report; I don't really see a reason to doubt it. As far as further damage from near misses, French sources may clarify those.

 

8 Nov 1942: the 2700lb 16" shells fell at 25 deg, 1520 fps calculated from the range of 25,000 yards. Hits were:

1) detonated in empty secondary battery magazine.

2) detonated below after control station, Ordnance concluded that a heavy nose fragment of this shell punching a hole in the bottom was the cause of the after flooding.

3) passed through the ship striking only the funnel and other light plating, then into the water.

4) glanced off No. 2 barbette, lost based plug and filler didn't detonate

5) richoted off No.1 turret losing based plug and filler, gouging armor on barbette jamming turret.

 

No.4 and 5 were recovered and examined.

 

When JB resumed firing 10 November, it was attacked by 9 SBD-3's of VS-41 from Ranger, carrying 1000# bombs with 1/100 sec fuzes. Two hit the JB, one fwd one aft and chewed up a lot of light structure.

 

The interesting point to me is what caused the ship to settle. The second 16" hit seems plausible because it did punch a hole in the bottom. But the other account suggests the ship didn't settle for a while. Maybe pumps held the flooding from the shell hit, but later failed because of the bomb hit.

 

forward

   

 

aft

   

 

Joe

 

 

Obviouslly the first picture are the damages done by a 500kg bomb.

A 14h 58, le Jean Bart est touché par deux bombes. La première tombe près du guindeau, soulève la plage avant et provoque un incendie. La seconde atteint la plage arrière en détruisant toutes les superstructures sur une longueur de trente mètres au-dessus du pont blindé inférieur, elle provoque un incendie qui ne sera éteint que vers 20h00. De grandes quantités d'eau (4.500 t) pénètrent dans le Jean Bart le faisant ainsi s'échouer par l'arrière. http://www.netmarine.net/bat/croiseur/jean...rt/histoire.htm

[Durandal]

Originally posted by JOE BRENNAN:

The visible damage fore and aft is from the bombs, .01 sec fuzed 1000# GP bombs.

 

Joe

 

oops sorry, we are agree then.

[Colin Williams]

BTT