Comparisons of Axis vs Allied Combat Vessels

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Tom17
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Tom17 » Mon Mar 09, 2015 7:35 am

Regarding torpedo hits one has to account for the different warhead weights.
Would, for instance, Pola, Newcastle or even Myoko, have survived one Long Lance hit in the same location as their historical hits?
Or would Edinburgh have survived three air launched torpedoes?
Tom

jpatrick62
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby jpatrick62 » Sun Jul 26, 2015 11:45 pm

I don't think the assertion that Allied warships in general were not tested for design deficiencies because they did not take battle damage is totally correct. For instance the Yorktown, a fleet carrier of the USN took enormous damage (for an unarmoured carrier) and still did her job. We see she took 3 - 500 lb bomb hits from Japanese Vals and 2 hours later is recovering aircraft and launching a return strike! In fact, the Japanese came back later and put 2 torpedoes into the same carrier and believed they had sunk a 2nd American carrier. Still, the Yorktown did not sink, and was being towed to port after all that damage. It took 2 more torpedoes from a submarine to finish her off. In this battle, the IJN had numerical and technical superiority over the USN and still managed to get annihilated.

As a second point, you cannot compare torpedo battle damage without taking into account the relative charges. Being hit by a torpedo from and airplane in WW2 was significantly less serious than being hit by a submarine launched torpedo, simply because submarine launched torpedoes carried a much larger charge.

alecsandros
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby alecsandros » Mon Jul 27, 2015 6:52 am

jpatrick62 wrote:In this battle, the IJN had numerical and technical superiority over the USN and still managed to get annihilated.



OT:

The IJN was outnumbered 1.4 to 1 in terms of operational warplanes available on the morning of the battle (about 320 vs 227), if considering the forces on Midway. In terms of carrier based a/c only, the 4 Japanese carriers had 227 units, and the 3 US carriers had 232 units operational.

The Zero and Kate were superior to their US counterparts, but the Dauntless was arguably superior to the Val.

=======

USS Hornet was another example of extreme resilience to enemy attacks...

Mostlyharmless
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Mostlyharmless » Tue Jul 28, 2015 7:48 pm

Reading through this thread again, I notice the question, for example from Tom17, of how to compare the effects of hits by different torpedoes. One of the main issues is the comparison of Japanese Type 93 torpedoes with German, British and American torpedoes. My perhaps surprising take on this is that they may be roughly equivalent.

There is a thread which one can drop into the middle of at http://warships1discussionboards.yuku.c ... ce?page=10 which discusses particularly German torpedo warheads. http://www.navweaps.com/Weapons/WTGER_WWII.htm has these made of “hexanite” but comments that the weight is very uncertain stating: “Warhead weight for these torpedoes confilicts in many references. I have seen numbers as low as 617 lbs. (280 kg) and as high as 948 lbs. (430 kg). It is possible that the lower numbers were for torpedoes issued early in the war and then heavier warheads were introduced during the war.”

The same site gives the explosive compositions of World War II Torpedoes as:

SW18: 50% TNT, 24% HND, 15% Aluminum
SW36: 67% TNT, 8% HND, 25% Aluminum
SW39: 45% TNT, 5% HND, 30% Amonium Nitrate, 20% Aluminum
SW39a: 50% TNT, 10% HND, 5% Amonium Nitrate, 35 % Aluminum

HND = Hexanitrodiphenylamine.

Thus we can be fairly confident that a German G7 warhead was between 280 kg and 430 kg and contained aluminium :D

Again according to Naval Weapons http://www.navweaps.com/Weapons/WTJAP_WWII.htm Japanese Type 93 torpedoes contained 490 kg of Type 97 explosive, which was identical to German WW1 “hexanite” and was about 7% more powerful than TNT, until 1944 when larger charges entered service. The submarine launched Type 95 model 1 carried 405 kg of the Type 97 explosive but from 1944 the model 2 with a 550 kg warhead and shorter range entered service and that presumably sank Indianapolis.

Most American torpedoes that hit anything and exploded contained 600 lbs (air dropped) or 668 lbs (submarine launched) of Torpex, which is a mixture of 37-41% TNT, 41-45% RDX (cyclonite, cyclomethylene trinitramine) and 18% aluminum. Torpex is roughly 50% more powerful than TNT. USN destroyers seem to have used 801 lb TNT warheads until there were no more targets.

RN submarines changed from 722 lbs. (327 kg) of TNT to 805 lbs. (365 kg) of Torpex in 1943.

Thus the higher power of non-Japanese explosives would seem to compensate for their lower weight.

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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Garyt » Wed Jul 29, 2015 12:41 am

. For instance the Yorktown, a fleet carrier of the USN took enormous damage (for an unarmoured carrier) and still did her job. We see she took 3 - 500 lb bomb hits from Japanese Vals and 2 hours later is recovering aircraft and launching a return strike! In fact, the Japanese came back later and put 2 torpedoes into the same carrier and believed they had sunk a 2nd American carrier.


If you are comparing the hits the Yorktown took to how many hits the Japanese carriers took at Midway it would seem the Yorktown was extremely durable. However, the Japanese carriers were hit with many armed and fueled planes on deck, and with the fuel mains filled with AVGAS, To make it worse there was excess ordinance around due to the switching from bombs to torpedoes.

The US carriers on the other hand throughout the war had the advantage of radar (Japanese radar being used effectively no sooner than Santa Cruz), so US carriers could prepare for an attack draining AVGAS lines, getting rid of ordinance filled planes, etc. etc.

Also calling the Yorktown "unarmored" is not exactly correct. Unarmored flight deck yes, but like most carriers she had an armored main deck.

A more accurate comparison to the damage the Yorktown took would be the Shokaku at Santa Cruz. She took 3-6 thousand pound bombs. While she stayed seaworthy, her flight deck and hangars sustained pretty severe damage. But she made it back for repairs.

The "fragility" of Japanese carriers has much to do as to what state they were in when hit, as in relation t flight operations.

Another comparison would be the USS Franklin, hit by 2 550 pound bombs while conducting flight operations. She was nearly sunk and severely damaged.

One other thing that is a factor - the Vals and other Japanese dive bombers generally carried an SAP bomb with a lower explosive content as a percentage than the US 1000 pound bombs frequently carried by the Dauntlesses. So not only were the japanese bombs smaller, they carried less explosive per pound of weight. The SAP bombs could pierce cruiser armor but eve HE bombs can pierce the flight deck of a carrier unless that flight deck was armored. Never understood the rationale behind the 500 pound SAP bombs.

Mostlyharmless
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Mostlyharmless » Thu Jul 30, 2015 12:02 am

I suspect that Franklin was only hit by one bomb. Some of the arguments can be found at http://www.j-aircraft.org/smf/index.php?topic=5878.15. There is an interesting similarity and contrast between Franklin and Hiryu. In both cases, power was lost because the engine rooms had to be evacuated despite no actual damage to machinery below the main armoured deck. In the case of Hiryu, this was an inevitable consequence of the small size and the double hangar design. Hiryu's main deck was the floor of the lower hangar and the roof of the machinery compartments. Thus heat from the fire above was radiated down from the red hot roof and actually killed some sailors who remained at their posts. In the case of Franklin, power was lost because of a defect in the design as the only source of air to the machinery compartments was from the burning hangar area and the very hot and smoky air forced an evacuation.

The Yorktown Class carriers were hard to sink as shown at Midway and Santa Cruz. However, both Yorktown and Hornet lost propulsion when hit by two torpedoes. The loss of power was not explained by flooding and was not well understood when the reports, http://www.cv5yorktown.com/Documents/Reports/Loss/ and http://ibiblio.org/hyperwar/USN/WarDama ... rtCV8.html, were written. Thus it seems that some of the machinery could be disabled by shock.

This is not unique to USN ships. For example, Unryu lost power after one hit despite having a centre line bulkhead http://www.combinedfleet.com/unryut.htm which led to her loss. Similarly, Hiyo lost power after being hit by two torpedoes on 10th June 1943 but was able to resume steaming at low speed after repairs http://www.combinedfleet.com/hiyo.htm. However, Hiyo's near sister Junyo survived two torpedo hits on 9th December 1944 but only lost one engine room and could continue at 13 knots (Junyo had also survived a single hit the year before) http://www.combinedfleet.com/junyo.htm. If I wanted to be provocative, I would argue that converted liners performed better than purpose built warships :D

Finally, I have to agree that the IJN did not always make the best choices of bomb. The use of a 250 kg semi-AP bomb may have been justified from the D3A1 as the power is only 1,070 hp for take off which is less than an SBD, suggesting that a 500 kg bomb might often require too long a run to get airborne. However, the D3A2 used at Santa Cruz with 1,300 hp could surely have dropped 500 kg bombs on Enterprise.

Garyt
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Garyt » Tue Aug 04, 2015 9:24 pm

I would argue that converted liners performed better than purpose built warships :D


LOL, you may have a point there. However, most of the Japanese carriers that were destroyed easily were the ones that took bombs while air operations were going on.

It's tough to compare the Yorktown class to the Japanese carriers at Midway. Drop a 1000 pound GP bomb or two or three on Yorktown class carriers that are conducting flight operations, and we would get a better comparison. The Shokaku class seems to compare well to the Yorktown class when looking at Coral Sea and Santa Cruz.

One distinct advantage that is often overlooked that most US carriers had - the open hangar. It conveys a lot of advantages to carrier survivability. It's easier to jettison ordinance if hit, explosions are not as contained meaning the vent to the outside better so they are not as destructive to the carrier, It makes it easier for other vessels to assist in damage control as well.

One thing that seemed to haunt Japanese carriers was explosions well after an attack due to build up of fumes from ruptured AVGAS tanks and lines. This of course doomed the Taiho, and they were unable to ventilate properly to rid themselves of the gas buildup. They even resorted to smashing portholes out to no avail.

Interesting also as the only US carrier to suffer from an explosion of built up gas fumes that I am aware of was the Lexington, and to my knowledge she was of a closed hangar design.

Steve Crandell
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Steve Crandell » Thu Aug 06, 2015 8:35 am

The Japanese DC organization left a lot to be desired. It was a specialist organization. If there was damage, everyone not in the DC specialty tended to stand around and watch. In the USN at least, everyone was a DC participant.

Garyt
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Re: Comparisons of Axis vs Allied Combat Vessels

Postby Garyt » Thu Aug 06, 2015 7:32 pm

I've heard that as well, Steve. IIRC, the US was probably a bit better prior to Coral Sea, but after Coral Sea they put a major emphasis on getting everyone trained in damage control, as well as providing more hardware on board to help, such as dramatically increasin the number of portable fire extinguishers.

Funny that as well as the Japanese were trained taht they lagged behind in damage control, at least damage control where everyone played a role.


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