Near misses

[String]

ORIGINAL: Dili

Yes -did Kate bombed in level flight?- but that doesn't changes anything in argument.

Yes they did.

[Dili]

Thanks. Btw just came across this image:

[herwin]

ORIGINAL: Dili

Yes -did Kate bombed in level flight?- but that doesn't changes anything in argument.

I'm not sure what you're arguing. In 1941, the Japanese had to plan an attack on Pearl Harbor in a way that would produce a reasonable payoff for the political costs. They believed that their D3As could kill US carriers and destroyers, but they had to deal with the American heavy gunships as well. Given the characteristics of the anchorage, they were aware they couldn't use torpedoes for more than a few ships, so they modified 16" projectiles to serve as AP bombs that could be dropped from high level by the B5Ns on the remaining gunships. What happened in the Indian Ocean later was a complete surprise--they learned D3As could kill heavy gunships using near-misses.

So a realistic model of bomb damage as a function of distance from the center of a ship deck and AP penetration capability is funny. If the bomb can't defeat the target's deck armour, direct hits do minor damage (a few weeks at most to repair), near misses (perhaps up to 50 feet) do serious damage or produce critical hits with a lot of dispersion, and misses further away do minor damage (sprung plates at most). Penetrating hits are more serious, but not usually as serious as a close near miss.

There are a number of people who read this site, who now could probably come up with a probabilistic model of the terminal effects of bombing damage. Initially, they would have to condition on waterline area, underwater protection, deck armour protection, bombing accuracy, and vulnerability to fire, but after modelling a few representative ships, they could probably come up with an adequate simple model that could be dropped into your generic operational naval wargame.

[Dili]

What happened in the Indian Ocean later was a complete surprise--they learned D3As could kill heavy gunships using near-misses.

Where is the evidence they were killed by near misses when they were burning and AA magazine exploded and have had several hits and were a complete wreck? And what is the surprise in that when same happened in Crete?

[Subchaser]

ORIGINAL: Dili

You said that streching it to unbelivable levels of surprise. You even said that a certain class of DD's resisted several 1000lb bombs to stress that point...How can they'll be surprised when in Crete cruisers were sunk right and left... and if they were so certain of not being surprised why they didn't developed a 500kg bomb for Val?

I do not understand what you’re trying to say. The main point of my post is that direct hit and near-miss scored by the same ordnance type cause different damage to a ship, direct hit – mostly system damage, near-miss – mostly flooding damage and the latter usually is more serious. I was talking, first of all, about HE and GP ordnance of small and medium caliber, that cannot penetrate armor or cause serious damage hitting topside, but can cripple a ship with a number of near-misses. If damage system completely ignores such damage factor, one can see dozens of bombs, with “penetration” lower than ship deck armor, simply bounce off the ship’s deck and do very little damage. As we know now, near-misses effect, or something like that, is in the game. 800kg and other high caliber AP-bombs can produce deadly near-miss shockwave only in shallow waters, in open seas, the only way such bombs can damage a ship is direct hit. It doesn’t matter were Japanese surprised with effectiveness of their 250kg bombs against armoured ships or not, the point was – nobody knew before the war how deadly near-miss can be, Germans as well, they were usually using AP bombs against enemy ships. I suppose you simply didn’t notice that I’ve already said about 500/1000lb bomb typo, it should 500lb bomb there.

[Subchaser]

ORIGINAL: Dili

What happened in the Indian Ocean later was a complete surprise--they learned D3As could kill heavy gunships using near-misses.

Where is the evidence they were killed by near misses ....?

Report on the sinking of HMS Cornwall by air attack on Sunday, 5th april 1942
(ADM199/2067, PRO, Kew, London). Acting Commander John Fair, RN.

[herwin]

ORIGINAL: Dili

What happened in the Indian Ocean later was a complete surprise--they learned D3As could kill heavy gunships using near-misses.

Where is the evidence they were killed by near misses when they were burning and AA magazine exploded and have had several hits and were a complete wreck? And what is the surprise in that when same happened in Crete?

The IJN did not have access to RN after action reports, and the Battle of Crete took place during 1941, so there wasn't enough time for the information to filter via other pathways. It does appear the RN learned about their vulnerability to near misses the hard way--losing a CL to an Bf109 attack does seem a little extreme.

[John Lansford]

If a bomb successfully penetrates the belt armor, does it inflict flotation damage on the ship?  Are mines subject to belt armor penetration checks?  ISTM that a bomb exploding in a 'near miss' functions more like a mine than a bomb at that point, especially 'influence' mines that used electric or magnetic detection features instead of contact.

[Subchaser]

ORIGINAL: John Lansford

If a bomb successfully penetrates the belt armor, does it inflict flotation damage on the ship?  Are mines subject to belt armor penetration checks?  ISTM that a bomb exploding in a 'near miss' functions more like a mine than a bomb at that point, especially 'influence' mines that used electric or magnetic detection features instead of contact.

Yes. The same physics here. Underwater explosion, doesn’t matter is it bomb or mine, creates shockwave that hits ship’s hull. I don’t think we can talk about penetration here, shock and cavitation damage do not always break armour plates, they can remain intact when pressed into the hull. I recommend to read Reid’s report, chapter 2. Hull damage.

http://dspace.dsto.defence.gov.au/dspac ... 0%20PR.pdf

Shockwave breaks hull, and there goes flooding, how serious damage can be depends upon charge size, orientation and proximity to the hull. Influence mines are more effective since shockwave hits directly underneath.

[John Lansford]

I was wondering if the bomb damage from a near miss in WitP was treated similar to a mine, though.  I keep seeing the "bomb hits belt armor" notes but don't know if the damage is like that of a mine in the game.  I've certainly never seen a mine hit indicate if belt armor penetration was even considered, though.

[Dili]

I do not understand what you’re trying to say. The main point of my post is that direct hit and near-miss scored by the same ordnance type cause different damage to a ship, direct hit – mostly system damage, near-miss – mostly flooding damage and the latter usually is more serious.

Well my point is that you overstress that.

The IJN did not have access to RN after action reports, and the Battle of Crete took place during 1941, so there wasn't enough time for the information to filter via other pathways. It does appear the RN learned about their vulnerability to near misses the hard way--losing a CL to an Bf109 attack does seem a little extreme.

The Japanese had military representatives in Mediterranean. He made a touring in Taranto after British attack for example.

losing a CL to an Bf109 attack does seem a little extreme.

A 250kg bomb is a 250kg bomb. It depends were they hit. A cruiser or even a battleship is not all armored. If the bow and the stern is broken by bombs and most of it is not armored enough they would be in serious trouble.

[herwin]

ORIGINAL: John Lansford

I was wondering if the bomb damage from a near miss in WitP was treated similar to a mine, though.  I keep seeing the "bomb hits belt armor" notes but don't know if the damage is like that of a mine in the game.  I've certainly never seen a mine hit indicate if belt armor penetration was even considered, though.

Given the orientation of belt armour, the idea that a bomb would hit it very frequently is risible.

[spence]

Water transmits the shock of the explosion better than steel would. The problem with the current model is that the belt armor (particularly) provides too much protection from GP bombs. The almost instantaneous fuse delay and metal sheathing that would ordinarily play a role in insuring a GP bomb would explode harmlessly outside of a ship's vitals are irrelevant when considering the effects of a detonation in the water alongside. Different physics.

[witpqs]

ORIGINAL: Dili

A 250kg bomb is a 250kg bomb.

This is quite false. Different bombs of the same weight have different amount of explosive ('bursting charge'). For example an AP bomb has far less explosive than an HE bomb. Also, an AP bomb might not even explode if it misses, or might explode much farther down in the water column to matter. This is only a sample, there are great variations among different bombs of the same weight.

[herwin]

ORIGINAL: witpqs

ORIGINAL: Dili

A 250kg bomb is a 250kg bomb.

This is quite false. Different bombs of the same weight have different amount of explosive ('bursting charge'). For example an AP bomb has far less explosive than an HE bomb. Also, an AP bomb might not even explode if it misses, or might explode much farther down in the water column to matter. This is only a sample, there are great variations among different bombs of the same weight.

The damage done is a function of the bursting charge, not the bomb weight. The explosion transfers energy from chemical bonds in the charge to the ship, with the transfer mechanism being the fragments of the casing and shock wave. The damaged volume is theoretically proportional to the charge weight, but since the damage resistance of the ship is proportional to its waterline area, the effect of a bomb (and also penetrating shells) essentially becomes proportional to the 2/3rds power of the charge weight. The same analysis reduces the effect of torpedoes, mines, and bomb near-misses to the 2/3rds power of the charge weight.

This, combined with analysis of gunfire systems leads to the interesting conclusion that light gunships were more effective than the same tonnage bound up in heavy gunships. Two 10,000 ton cruisers had about the same combat power as a 35,000 ton battleship. The advantage of heavy gunships was in their protection (and their ability to defeat the protection of other heavy gunships).

[Ron Saueracker]

ORIGINAL: witpqs

ORIGINAL: Ron Saueracker

Ahhhh...germs vs a naval combat and damage model worthy of a WW2 game of the Pacific? Get real Gary. We have individual pilots, personal weapons, leaders etc but ships are crewless (aside from a skill factor) and have armoured paint. Not bitching really but I'm not going to make ridiclous comparisons either.[8|]

It is my understanding that way, way back in the dim recesses of time individual pilots and various other detail-type goodies were added at the request of the community. When you specifically request something and then get it that item is not a legitimate wedge to use to criticize the design of the game.

As was a revamped naval combat and ship damage model. But no joy. Hey, not criticising, just taking part in the thread.

[Ron Saueracker]

ORIGINAL: Subchaser

Ron, what kind of examples do you want, ships actually sunk by near-misses or examples of a different way of weapon and armor systems interaction compared with direct hit?

Bomb near-misses and gravity of the shock was a hidden problem that no one fully realized before the world war 2. This issue only became apparent with the magnetic mines used in 1939 and when the ships started taking bomb near misses. Interesting fact is that initially naval air attack doctrine was based on near-miss tactics tested by general Mitchell and his provisional air brigade in 1921.

“Mitchell took command on May 27 after testing bombs, fuzes, and other equipment at Aberdeen Proving Ground and began training in anti-ship bombing techniques. Alexander Seversky, a veteran Russian pilot who had bombed German ships in the Great War, joined the effort, suggesting the bombers aim near the ships so that expanding water pressure from the underwater blasts would stave in and separate hull plates. Further discussion with Captain Alfred Wilkinson Johnson, Commander, Air Force, Atlantic fleet aboard USS Shawmut, confirmed that near-miss bombs would cause more damage than direct hits by causing an underwater concussive effect against the hull.”

“Sinking of the Ostfriesland. NBS-1s dropped six bombs in quick succession between 12:18 p.m. and 12:31 p.m., aiming for the water near the ship. There were no direct hits but three of the bombs landed close enough to rip hull plates as well as cause the ship to roll over. The ship sank at 12:40 p.m., 22 minutes after the first bomb, with a seventh bomb dropped by the Handley Page on the foam rising up from the sinking battleship. Navy studies of the wreck of the Ostfriesland show she had suffered little topside damage from bombs and was sunk by progressive flooding.”

Before ww2 this issue was often overlooked in all major navies. Prewar doctrine for the IJN, USN, and RN, all leading carrier powers, believed that armoured warships could not be sunk by bombs alone. The sinking of the light cruiser Konigsberg in Bergen harbor by Skuas equipped with 500lb. bombs was considered an aberration cause she was stationary target in shallow water harbor where the concussive effects of the near miss bombs were magnified.

It’s well known what IJN dive-bombers achieved in the early war stages, but few know that this success came as a shock surprise to IJN. Standard 250kg GP bomb carried just 133lb of explosive, designed by Kure arsenal, it supposed to be used against the wooden decks of American carriers, which it could pierce with ease and penetrate into carrier’s vitals resulting fatal damage to the vessel, in the same time, these bombs were not supposed to be capable of sinking such heavily armored vessel as battleship outright, nor were they intended to. When used against ships with armoured decks, their function was to suppress the exposed gun positions, damage communications and wreck the upper works, all of which would allow the real killer – torpedo-bombers, to make their own vulnerable attack approach with immunity. Vals used 250kg GP bombs against battleships at PH solely because their primary target, USN carriers were not present. Used against medium-armoured ships like CA, it was hoped that these bombs could be effective enough to sink such warship, but only if an overwhelming number of hits was attained. Isolated hits on CA, or up to 4-5 direct hits should not normally sink such a ship, at least nobody expected that. The fact that the Vals actually sank, quickly and decisively, heavy cruisers Dorsetshire and Cornwall in the Indian Ocean in April 1942 absolutely shocked IJN naval specialists who did not believe that bombs alone could sink any ship larger than a destroyer. Surprisingly fast IJN expert team lead by Commander Obata had figured out that fatal damage was caused by “hydroshock effect” of numerous near-miss hits, later in 1942 IJN initiated two projects in experimental centre in Migure where they tried to develop “Ii-tan” type HE bombs, specially designed hydro-shock bombs to be used by Rikko units.



Just about any deck armor is sufficient to force the HE/GP ordnance to explode. The damage caused is then typically limited to the target's upper works. Bomb hits upper deck and it’s enough to trigger the fuse. That way, the bomb explodes before reaching the armor deck, and usually does not damage the engineering spaces or magazines. Armored decks were impervious to penetration by HE bombs. However, as events showed, armoured ships subjected to attack by 500- 1000lb HE bombs saw some damage above the armor deck, while near misses breeched any underwater protection. It’s hard to figure out how many ships were sunk exclusively by bomb near-misses, but I think it’s not that necessarily for making the point clear, when warship came under serious air attack it usually got some direct hits along with near-misses, more important is what damage reports claim as a major damage factor, and quite often it turns out that underwater explosions did most of the battle-damage. HE ordnance that could do only limited damage topside sometimes breeched hull below waterline and was as effective as torpedo that way. Read any USN carriers damage reports, Lex, Yorktown, Big E they all were seriously damaged by near-misses. In some cases, near-misses were the only way to damage fast, maneuverable vessel with narrow hull like, for example, CL Yubari. On 10th Marh 1942 Yubari survived furious USN air attacks, she evaded 67 bombs and 12 torpedoes, no direct hits were scored, however she was damaged. A couple of days she was again “missed” by B-17s at Rabaul and departed for battle-damage repairs at Truk, no direct hits were scored on her. During Guadalcanal campaign a lot of ships were heavily damaged or sunk by near misses in shallow waters, on 11th october 42, SBD pilot Lt.Cdr John Eldridge attacked IJN destroyer Natsugumo and got a close near-miss. Underwater explosion caused uncontrollable flooding and the ship capsized 40 minutes later. One, single near miss by 1000lb bomb was enough to sink 2400t. ship, note that Asashio class DD were capable to withstand several direct 1000lb hits. 6 days before her sinking Natsugumo was escorting her sister Minegumo back to Shortlands, Minegumo was near-missed by two 500lb. bombs in shallow waters, although both bombs exploded quite far from the ship, there was serious flooding and the top speed went down to 13 knots.

It’s hard to analyze damage reports of all ships sunk during the war, so I took only IJN heavy cruisers damage reports. All 18 warship were lost due

Fatal damage caused by torpedoes – 10
Fatal damage caused by own torpedoes explosion – 3
Fatal damage caused by near-misses bombs – 3
Fatal damage caused by artillery fire – 1
Fatal damage caused by direct hit bombs – 1

IJN cruisers sunk by bomb underwater explosions
Kinugasa – 1 x 500lb direct hit (gun mount disabled) + 7 x 500lb near misses (fatal damage)
Aoba – 1 x 500lb direct hit, 1 x 2000lb near miss in shallow waters and she was just hull after that.
Tone – 3 x 500/1000lb direct hits (medium system damage), 7 x 500/1000lb bomb near misses (flooding – fatal damage), ship beached with main deck above the waterline.

Many IJN light cruisers were heavily damaged by near-misses, and for example CK Oyodo got 6 500/1000lb near misses during the final attack on her on 28 july ’45, no direct hits, and sunk.

Here is an interesting report on the subject. It’s way scientific, a lot of formulas, but still worthy to look at.

The Response of Surface Ships to Underwater Explosions. By Warren D. Reid
http://dspace.dsto.defence.gov.au/dspac ... 0%20PR.pdf

“An underwater explosion detonated nearby a ship can in many situations, be devastating to the combat readiness of the vessel. Damage to a vessel may occur in the form of dished hull plating or more serious holing of the hull. However some damage may not be obvious and could occur as a result of shock-wave loading of equipment and systems aboard the vessel. Equipment damage may incapacitate a vessel. Much research effort has been expended in the study of underwater shock, especially during the period after World War II, where it became obvious that many navy vessels could be disabled easily by a non-contact underwater explosion.”

Heyho, SC. Yep, these suffice.[&o]

[Howard Mitchell]

ORIGINAL: herwin
It does appear the RN learned about their vulnerability to near misses the hard way--losing a CL to an Bf109 attack does seem a little extreme.

herwin, just curious - which ship was this?

[John Lansford]

ISTM that near misses on warships should be similar to mine damage; creates flotation and perhaps system damage, and the belt armor is ignored as it is for torpedo hits (seriously, has anyone seen a torpedo NOT penetrate the belt armor?).  Perhaps in AE this would be represented as minor flotation damage with a small amount of major damage thrown in for the larger bombs.  I realize this isn't going to be added so late in development, but it would be nice to at least have it considered for a patch in the future.

[herwin]

ORIGINAL: Howard Mitchell

ORIGINAL: herwin
It does appear the RN learned about their vulnerability to near misses the hard way--losing a CL to an Bf109 attack does seem a little extreme.

herwin, just curious - which ship was this?

Fiji

"She was attacked and hit by several bombs from Messerschmitt Bf 109s before an aircraft of Jagdgeschwader 77 dropped a bomb close alongside to port. This blew in Fiji’s bottom plates and caused a list to port. Fiji lost power and came to a standstill. She was now largely defenceless, having practically exhausted her 4 inch ammunition. She was then hit by three bombs dropped by a Junkers Ju 87. Captain William-Powlett gave the order to abandon ship and at 2015 Fiji rolled over and sank."

"The FIJI, after having survived some 20 bombing attacks in four hours,
was hit by a bomb from a single Me 109 aircraft which flew out of the
clouds in a shallow dive and scored a hit very close to the port side
amidships. The ship took up a heavy list, but was able to steam at
reduced speed until half an hour later, when another single machine
dropped three bombs which proved fatal. Destroyers which returned after
dark rescued over 500 of her crew, but 16 officers and 228 ratings
were lost."