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wpurdom -> (7/31/2002 11:03:05 AM)

I don't necessarily disagree with Nikademus's analysis on the bombs, but since I don't find the case clear and convincing with respect to CA's, let me play devil's advocate.

"but look at the preformance of Mikuma and Mogami at Midway? They collided, got crippled, got pounded all day from Midway and Two carriers full of SBD's and one still got away while the other only slowly surcombed with it's topsides a shambles."

According to Morrison, "pounded all day" amounted to three attacks on the 6th of 26, 31, and 24 SBD's respectively. (One attack from Midway on the 5th got only near misses while the CV attacks diverted to the DD Tanikaze which dodged over 50 SBD's and shot one down - the boys seem to have been a little off from the 4th).
The two attacks on the Mogami: 2 hits in the first attack, one hit penetrated the No. 5 turret and killed everyone within. Morrison describes 3 hits in the second attack, two started fires and a third sealed up one burning engine room and killed over 90 men. Result, Mogami made it to port, but it was over a year before it was repaired.
How many bombs hit the Mikuma? I don't know, but it appears from the picture that everything above the deck, including all of the guns was rendered into scrap metal, the ship was wallowing low in the water and was abandoned after the 2nd attack. Given what happened to the Mogami and to the Mikuma's guns, it seems clear that those HE bombs can do a lot of system damage to CA's and it is probably expecting too much from the game to simulate all of the fine points of the different damage inflicted. Probably a lot of the damage is done without the penetration of armored areas.
Also, with respect to Japanese ships, one doesn't have to sink them to put the out of the war. Enough system damage and it will overload repair capabilities and make the ship so much scrap metal.
In contrast, the Nagato and Yamato were each hit by 2 1000 lb. bombs the first day at Leyte and their fighting abilities were unimpaired, again according to Morrison. The Nagato was also hit by more 1000 pound bombs the next day, but remained undamaged. The Mushashi got hit by torpedoes (10!) and went under.



Nikademus -> (7/31/2002 11:33:11 AM)

[QUOTE]Originally posted by wpurdom
[B]I don't necessarily disagree with Nikademus's analysis on the bombs, but since I don't find the case clear and convincing with respect to CA's, let me play devil's advocate.

"but look at the preformance of Mikuma and Mogami at Midway? They collided, got crippled, got pounded all day from Midway and Two carriers full of SBD's and one still got away while the other only slowly surcombed with it's topsides a shambles."

According to Morrison, "pounded all day" amounted to three attacks on the 6th of 26, 31, and 24 SBD's respectively. (One attack from Midway on the 5th got only near misses while the CV attacks diverted to the DD Tanikaze which dodged over 50 SBD's and shot one down - the boys seem to have been a little off from the 4th).
The two attacks on the Mogami: 2 hits in the first attack, one hit penetrated the No. 5 turret and killed everyone within. Morrison describes 3 hits in the second attack, two started fires and a third sealed up one burning engine room and killed over 90 men. Result, Mogami made it to port, but it was over a year before it was repaired.
How many bombs hit the Mikuma? I don't know, but it appears from the picture that everything above the deck, including all of the guns was rendered into scrap metal, the ship was wallowing low in the water and was abandoned after the 2nd attack. Given what happened to the Mogami and to the Mikuma's guns, it seems clear that those HE bombs can do a lot of system damage to CA's and it is probably expecting too much from the game to simulate all of the fine points of the different damage inflicted. Probably a lot of the damage is done without the penetration of armored areas.
Also, with respect to Japanese ships, one doesn't have to sink them to put the out of the war. Enough system damage and it will overload repair capabilities and make the ship so much scrap metal.
In contrast, the Nagato and Yamato were each hit by 2 1000 lb. bombs the first day at Leyte and their fighting abilities were unimpaired, again according to Morrison. The Nagato was also hit by more 1000 pound bombs the next day, but remained undamaged. The Mushashi got hit by torpedoes (10!) and went under. [/B][/QUOTE]


Japanese heavy cruiser turrets were in actuality lightly protected. 25mm maximum . (a small OOB error in UV) A better example of a hit against a well protected turret would be one landed on the SoDak from before third Guadacanal. zero effect on the interior of the gunhouse though splinter damage did cause one or two barrells to be not fireable due to saftey concerns.

I agree, CA's are marginal in this argument and even some battleships have weak spots that can be exploited. I'm certainly not advocating immunity from the air (as opposed to below the belt hits) but as things are now, bombs are way too powerful. In effect its the other side of the coin in approaching the problem of LBA vs ships at sea. It wasn't just because the LBA units could go in at ultra low levels with no penality incurred. It was also due to the fact that all it would take is a small # of 500ILB bomb hits and you had major damage to everything up to a Kongo class battleship (3inch deck)

The experience of the Mikuma highlights the problem. "lack of armor penetration" does not equate to total ineffectiveness. A 1000ILB HE bomb will have more concussive effect than a shell that is rejected (unless battleship caliber). In game terms this could be represented as a high incendiary effect with maybe some moderate system damage even if a non penetration occurs. My only worry here is that i would not want to see such an effect carried over to shells as they'll tend to have less ability in this area, esp if firing AP.

so a bomb hitting for example a 2nd gen CA might repulse the bomb from penetrating, but suffer a certain number of fire levels which in turn could cause sys, weapons and propulsion damage if left unchecked but unless it penetrates the armor, little to no chance of floatation damage etc etc. But i dont know if UV works this way or if it can.

I dont believe such adjustments would make BB's "uber". For one.....even simple steaming assignments bring SYS damage representing the wear and tear effect of continous running and such. In such cases even a non penetrating hit will often add a few SYS points here or there that represent topside and unarmored area damages. vulnerability of light weapons systems and radar further would deter a player from brazenly steaming his warships into dive bomber range

bombs can hurt a battleship, but they will rarely cripple it. However in a strategic/operational campaign, the player doesnt often have the luxery of playing like there's no tommorrow. Thats the balance factor. It remains though that torpeodes were what battleship captains truely feared as those weapons avoid armor and at the same time strike below the water causing the nightmare of progressive flooding (as well as slowing the ship making it progressively easier to hit)

cruisers fall between so what i'd suggest as before since i was asked and given what my own research turned up, i'd say less than 1 inch for a 500ILBer (which would make them dangerous to all AP AK, DD, and most CL, CS types and unarmored CV's) and 1000ILBers around 2 inches (convienient as most CA's have a 50mm deck.....if UV works like a Grigsby game of the past....this should allow an on and off chance of penetration.

outside of brute penetration, should be added the incendiary/blast effect...though this is a little broken in UV so your right....it might upset the game balance as it stands right now

Nagato and Musashi are good examples too. The bombs had little chance to get through but the explosive effect could sometimes cause fires to spring up below decks from concussed machinery, to shorted electronics to compromised vents.

The main thing such a compromise would acomplish is that it would take the bombs down a knotch in the danger bracket for medium and heavy armored ships leaving torpedoes the gravest threat (as they should be) As it is right now.....bombs, esp 1000 pounders are equally dangerous to torps.

I'm hoping most of all that this discussion lends itself to WiTP if it turns out that UV's code is too rigid for this to be adequately simmed.



doomonyou -> This has been a really really interesting discussion.... (7/31/2002 6:09:30 PM)

that will be all....



Don Bowen -> Re: Re: this is going to sound sarcastic but its not.... (8/1/2002 10:25:13 PM)

[QUOTE]Originally posted by Nikademus
[B]

For one....a dive bomber screaming in at 200mph in a dive is going to tear it's wings off.

[/B][/QUOTE]

This didn't seem right when I read it, so I did a little research. From "SBD Dauntless Units of World War II" by Barrett Tillman and discussing early war tactics:

"Approaching the dive point at 14,000 to 15,000 feet, the squadron shifted from Vs to echelon. At this point each pilot took interval on the Dauntless ahead of him, reduced throtle and extended dive brakes. In a standard dive-bombing approach, the aircraft descended at 70 to 75 degrees to the vertical at some 240 knots. From 'pushover' to release altitude - usually 1500 to 2000 feet - the dive took 30 to 35 seconds.
(paragraphs omitted - discussed use of rear seat guns during dive and bomb types.)
After release, the pilot retracted the dive brakes, as the SBD would not easily maintain level flight with the brakes extended. Pullout was often left as late as possible so as to reduce exposure to enemy anti-aircraft and a high-speed jinking run was made to the pre-briefed rendezvous point."

And - related to the original topic of this thread:
1.2 ASW fixes seem very good. In a trial game, now in September, I've only had one SC sunk by I-boats. Score is:
Submarines sunk - 5 (all U.S.)
ASW Vessels Sunk - 1 (U.S.)
Other vessels Sunk by SS - 7 (6 Japanese and 1 Allied - all transports)

Land based Naval attacks are much more realistic - good job here too.

The B-17 repair rate fix over did it. Using Airfield attack at 31,000 feet (Port Moresby to Lea) with 2 Heavy Bombardment Squadrons I find it takes about a month to repair the damage from 1-2 days attacks. Another squadron whose altitude I forgot to raise from 10,000 dropped to 2 ready and 10 damaged on July 15th. Withdrew to Cooktown and set to training - as of September 9th is 7 Ready and 5 damaged (the damaged aircraft are still at Port Moresby). Note that I moved 2 new squadrons to Port Moresby when I withdrew the first, so the number of damaged B-17 at Port Moresby was always high.

Don Bowen

----------------------------
The stock market is easy. You buy stocks and, when they go up, you sell them. If they don't go up, don't buy them.

-- Will Rogers



seydlitz_slith -> (8/3/2002 11:16:57 AM)

Since the discussion regarding the Damage to the Mogami & Mikuma came up, I pulled out my copy of "Japanese Cruisers of the Pacific War" by Lacroix & Wells. This 882 page book is the most detailed work available in english print covering the WW2 Japanese Cruisers. It devotes 67 pages to the Mogami class alone.
According to pg 487-488...

The damage at Midway to the Mikuma was as follows:
0930am-hit by at least 5 bombs from the 2nd attack wave of 31 SBDs. Hits were:
1. No.3 turret, causing damage to the bridge where several people were killed or injured including Captain Sakiyama.

2. Two bombs hit starboard forward engine room.

3. Two bombs hit port Aft engine room.

The engine room hits brought Mikuma to a halt and started heavy fires in the torpedo room. The fires ignited the torpedoes, which exploded about 1058, wrecking the ship.Commander Takashima, the 2nd in command gave the order to abandon the ship.

Mikuma was not hit in the 1st or 3rd attack waves.
After the 3rd attack wave, Mogami, and 2 DDs rescued about 240 survivors from Mikuma and abandoned the drifting ship. After staying afloat all day, the wreck sank at an unknown hour during the night. The famous Pictures of the wrecked and burning Mikuma were made by two SBDS of VB-6 from the Enterprise in the afternoon, well after she had been abandoned.

650 men were lost.

If you look at the picture, you can tell that the most severe damage was from the torpedo explosion.

Mikumas damage from the collision with Mogami was above the waterline on the port side below the bridge. Other than trailing oil, the damage did not impair fighting ability or maneuverability.

Mogami:
The Mogami's bow was bent 90 degrees to port back to the number 1 turret from the collision, and the section of the ship from the bow to the #1 turret was flooded up ot the middle deck level making forward movement impossible. The bow section was, therefore, cut away, and after emergency repairs the Mogami was able to make 12 kts. (The collision was at 2318 hrs on June 5th.) By dawn on June 7th, she was able to make 14 kts.

The first wave of 26 SBDS attacked at 0645am on the 7th.
Mogami was hit twice.
1. 1 hit on No. 5 turret which penetrated and killed the turret crew.

2. 1 hit on the aircraft deck which started fires in the torpedo room below. Luckily the torpedoes had been jettisoned after the collision, and the fire was extinguished within an hour.

The second wave of 31 SBDs at 0930am on the 7th.
Mogami is hit twice.
1. 1 bomb hit amidships on the aircraft deck.
2. 1 bomb hit forward of the bridge.
Both hits caused medium damage.

The third wave of 24 SBDs at 1145am on the 7th.
Mogami is hit once.
1. 1 bomb scores a direct hit on the aircraft deck. This damaged the escape hatches of the engine rooms and killed the men fighting fires inside.

Yet, even after taking 5 hits, with casualties of 9 officers, 81 enlisted men killed and 101 people wounded, Mogami was still able to steam under her own power well enough to catch up to the invasion force by 0400am on June 8, and was able to rejoin sentai 7 an hour later. She reached Truk on the 14th.

It is important to note that even after the damage she sustained, she was able to work to take survivors off of the Mikuma.

For what it's worth,
Suzuya was lost on oct 25, 1944 in the following manner:
0735am attacked by 10 TBMs from TG77.4.3. This attack resulted in a near miss by a bomb on the port side aft. The damage put the port outboard propeller shaft out of order reducing speed to 20kts.
At 1050 she was attacked by 30 aircraft from TG 77.4.3. This attack resulted in a near miss from a bomb on the starboard side amidships. Since the no.1 (starboard forward) torpedo tubes were loaded, the near miss ignited the torpedoes in the tubes. The detonating torpedoes started heavy fires that were fought unsuccessfully because additional torpedoes started to explode at 1100. This resulted in the destruction of both aft (no.3 & 4) HA gun mounts and damage to the starboard engine room as well as stbd aft boiler room No.7. The ship became unmaneuverable.

At 1200 the fires detonated the remaining torpedoes, and the ammunition of No. 1 & 2 (both fwd) HA-gun mounts started to explode, setting the whole ship ablaze.

The ship was abandoned at 1300. 620 of the crew were rescued by the escorting DDs. The ship sank at 1320.
source was pg 498.

Conclusion:
At least in the case of the Mogami class, the deck protection vs bombs were adequate. However, the vulnerability of the torpedo mounts to bomb damage/ fire damage is what resulted in the loss of both Mikuma & Suzyua.

If it is worthwhile, I can look up any other Jap Cruiser related specifics in this book if this will contribute to the topic being discussed.

Regards,
Don



doomonyou -> bomb damage (8/3/2002 9:20:04 PM)

so than according to what you posted the cruisers could be destroyed by bombs. I would think that if the surviving was a little less lucky, it would have been blown to hell too. Just happened that thier torpedoes were dumped and that the turret hits set off no ammo. If one of the bombs had hit a little differently it sounds quite likely that the fires (or resulting secondaries) would have destoryed the ship. it can't be both ways. The Japanese ships can't have wickedly powerful huge torpedoes that are dumped overboard everytime an SBD is spotted.

All in all, I do not think that the bomb damage is so terrible...



seydlitz_slith -> (8/3/2002 11:26:31 PM)

My issue with the bomb damage seems to be more of the messages saying that the armor is penetrated, followed by internal explosions, etc.

This is probably the issue that others are having.

You can do severe damage without penetrating (evidence the Suzyua loss).

However, in the game, I see a lot more armor penetration messages from bomb hits on ships that were built with protecton from penetration. Perhaps additional damage messages could be added to the game to account for heavy non-penetrating damage, but there are some cases where bombs are penetrating where they shouldn't (with regularity).

Don



wpurdom -> bomb damage (8/4/2002 12:59:23 AM)

The fine post by seydlitz provides far more information than is in Morrison and, I think, clarifies the appropriate distinctions between damage to CA's vs. BB's. I find Nikademus's excellent postings on penetration of armor entirely persuasive on the issue of HE bomb damage to BB's. I think seydlitz's post shows that the CA's are an entirely separate issue. If the sort of damage actually inflicted by bombs on CA's are most closely modelled by penetrating hits in the game's model, then bombs should penetrate CA armor, even if that is not the actual mechanism through which the fires, explosions of torpedoes, and destruction of turrets is actually being caused.
We can't expect the programers to provide 15 different mechanisms for calculating damage depending on the type of weapon used. Torpedoes vs. non-torpedoes I presume are modelled in the game, and such a distinction does seem necessary to me.



wpurdom -> inquiry (8/4/2002 1:05:36 AM)

Anybody have any detailed information on bomb damage to US CA's by bombs or HE shells? (Damage to US ships at Cape Esperance and 1st Guadalcanal involved HE ammunition - the San Francisco, in particular, was pretty heavily damaged by the HE ammo but did not sink).



seydlitz_slith -> (8/4/2002 4:06:09 AM)

According to pp320-321 of U.S. Crujisers by Friedman (Naval Institute Press, 1984, 496 pages):

[begin quote]

The experience of the San Francisco, another New Orleans clas cruiser, is in sharp contrast to that of her three sister ships. She survived massive gunfire damage in the battle of Guadalcanal, on the night of 12-13 November 1942, against a Japanese force that included two 14-in gun battle cruisers. That evening she had already survived a Japanese torpedo bomber crashing into her after control stations, which started a severe fire and destroyed the after 8-in gun controls. Later she took about forty-five hits, most of them from the 5.5-in secondary batteris of the battle cruisers but two of them from 14-in guns. Structural damage was limited, because the Japanese had been using special bombardment rounds destined not for surfaced action but for Henderson Field. Moreover, although over twenty fires were started, they were promptly brought under control. At the end of the battle, she still had use of two of her three 8-in gun turrets, and five of her eight 5-in AA guns, although in the absence of splinter protection their crews had suffered badly. That is not to say that the ship escaped lightly. Peppered by fragments, she was without any means of exterior communications, and many of her electrical circuits, particularly aft, were cut. Among the 189 casualties were the admiral, his staff, the captain, and the executive officer.

Possibly the greatest difference between the damage done to the San Francisco and her three less fortunate sisters can be attributed to the fact that airplanes and other inflammables had been stripped from the San Francisco's hangar. Fortunately, her fire mains and engineering plant remained intact; none of the Japanese shell, not even the 14-in type, was armor piercing, and at short range all of the hits were well above the waterline because of ricochets and the tendency of short-bombardment shells to explode when they struck the water. From a design point of view it is interesting to note that neither the captain nor the admiral availed himself of the San Francisco's conning tower, which, incidentally, remained undamaged throughout.

[end quote]

My comments: Like the Mogami at Midway, the San Fran may have been lucky in having been hit by the torpedo plane earlier that day. Because of that, much of the flammable material had already been burned or jettisoned....in the same way Mogami was saved from the fate of Mikuma & Suzyua because the earlier collision had lead to the crew to jettison the torpedoes from the mounts, meaning that they were not there to burn and explode when she was hit by bombs in the later air attacks.

If anyone can come up with good cases to check involving either US or Japanese ships, I can look up the info as I have a good reference library on hand.

regards,
Don



wpurdom -> bomb damage (8/4/2002 10:11:56 PM)

CA Houston got a turret knocked out a few days before it was sunk. This is the only US CA I know of that got hit in 1942.

Also illustrative to this thread might be the CL Marblehead (same time) and the CLAA San Juan (Santa Cruz or Eastern Solomons) and the BB Nevada which got hit 5 times by dive bombers. If someone wanted to shift through a detailed account of Pearl Harbor, there might be a few other examples, but as Nikademus said, most of the damage there was done by Kates with either torpedoes or level bombing 16 inch shells.



HMSWarspite -> Re: Question? (8/5/2002 3:06:36 AM)

[QUOTE]Originally posted by denisonh
[B]What was the average repair time for heavy bombers in the PTO? Does anyone have any data or information to shed light on the subject?

Given the ETO had more resources, it still seems ridiculous that a B-17 takes a 20mm round in the fuselage and sits on the tarmac an average of 5 days to get repaired? (reference a previous post, avg time to repair = 1/probability of repair = 1/0.2 =5 days).

AVERAGE of 5 days with std dev of 4.47 Days. I would think 2 or maybe 3 as reasonable, but 5 is way too much. And is is not the average, but the variability that creates way too many down days. (as opposed to a 33% repair rate that represents an avg of 3 days to repair with a 3 days std deviation: so 16.7% chance of an a/c taking 7 or more days to repair)

I should theoretically be able to run heavy bombers then rest them for 3-4 days and have 80% ready assuming supply and support. This can't be achieved with 5 day average.

So you are telling me that I can run bombers once a week, or just get used to putting up 25% of my bombers for a mission?

I have heard the point of accurately simulating combat, and with the stated probabilities, it seems rather unlikely that this will be the case with regards to B-17 Ops. [/B][/QUOTE]

This (and other posts) started me on a little research. The heavy bomb groups of the 8th AF in UK managed an average of 1 mission per 2.24 days. This is an average of the missions/days in combat for all the groups. This may lead you to think that the repair time is too slow. However, several other things should be considered.

1. The data implies that the frequency of missions markedly increased in 1944-45 rel 1942-43. E.g.97th BG in 8th from Aug/Oct 1942, 14 missions in 65 days (4.6 days/mission). The 6 groups with the fastest mission rates all joined the 8th in 1944 (1.3-1.7 days/mission).

2. The 8th had a major support set up (unlike a few BS stuck in the middle of the South PAcific)

3. These raids are without exception medium/high alt 8th AF routine jobs.

4. The BG were putting up just under 28a/c per group per mission. This is harder to work with due to changes in BG strength. IIRC a 36a/c BG (4 BS of 9a/c) was expected to put up a 18a/c box in 1943, sometimes 21a/c. By 1944-5 the BS strength had been increased, and the boxes were 27-30. Some BG AVERAGED 33a/c per mission. Either way, we seem to have 50% strength in the air for missions.

5. This means that (on average) the 8th AF managed to put up 50% strength just worse than every other day. Now some of this will be ETO weather driven but cannot judge this.

What does this mean on repair time - well, can't really tell, however, the average BG lost 0.4 a/c per mission, whilst achieving the flying rates above. If you take say 4 damaged a/c per shoot down in ETO (flat guess), each group has one a/c to repair per mission. I.E. repair probably isn't an issue on average, only after tough missions. Thus the repair time could be almost anything (sorry, if you were hoping for something better!:)) Subjectively, I could quite believe 5 days as average repair time in the PTO in 1942. Unfortunately I could also beleive 4 days!:D

Final point on 8th AF - for the BG I have data for, they lost 0.07a/c per day in operational losses each. (the losses rising later to say 0.1 a/c per day with the later bigger BG)
[Source for all this: The Mighty Eighth, R A Freeman, Cassell & Co, ISBn 1-85409-531-5]
Editted to correct finger trouble!



Don Bowen -> B-17 Repair rates (8/5/2002 3:50:08 AM)

I am running a test game based on scenario 17 - currently in mid-October, 1942. I have 5 B-17 squadrons "on line" and another attempting to recover in Australia. I am seeing about 1 B-17 repaired every 5 days or so. That is not 1 per squadron, just one. I have one squadron that had 10 damaged in July and still has 4. That's 6 repairs in 90 days.

The rate of 4-5 days per aircraft doesn't seem out of line, assuming multiple aircraft are under repair concurrently. It's just not right to have multiple damaged aircraft repaired sequentially - one coming back on line every 5 days or so.

Don



doomonyou -> don's exactly right... (8/5/2002 3:57:47 AM)

especially if your doing it at a size 9 airfield, it might not be the facilities near the coast of dover, but an airfield that size should be able to completely rebuild 1 per day, not one per five days.(espeically as in my test I have 375 air support at size 9 PM). I wouldn't mind if it was still sequential, but it should be one per day sequential.



HMSWarspite -> Re: Question? (8/5/2002 5:22:26 AM)

[QUOTE]Originally posted by denisonh
[B] (reference a previous post, avg time to repair = 1/probability of repair = 1/0.2 =5 days).

AVERAGE of 5 days with std dev of 4.47 Days. I would think 2 or maybe 3 as reasonable, but 5 is way too much. And is is not the average, but the variability that creates way too many down days. (as opposed to a 33% repair rate that represents an avg of 3 days to repair with a 3 days std deviation: so 16.7% chance of an a/c taking 7 or more days to repair)
[/B][/QUOTE]

I missed this on my last post - must be tired:(
I don't know where the P(repair)=0.2 comes from, but assuming true, you have to be VERY careful when you say the average repair time is 5 days. For example: 20% chance to repair =80% to not repair. The probabilities of NOT being repaired after x days are:
days Prob
1 80
2 64
3 51.2
4 40.96
5 32.77
6 26.21

Now, if the 20% figure is true, half your a/c are actually repaired in 3 days or less(i.e. median repair time is 3 days). Has someone done some tests, or can you point me to the thread that gives the 20% (or what it is)
The 33% repair rate (also mentioned above) gives
1 67
2 44.5
3 29.7
4 19.8
5 13.2

The arithmetic average for a 20% p(repair) may be c 5 (4.6 in a quick test I did with excel, but the stats are dodgy in excel), and the SD c4 (3.9 in my test). However, the constant repair % gives a squewed population. I will try and work out what % of a fleet is active with 20% repair prob, and various damage rates sometime.

Not really relavant to the game, but here it is anyway!;)



denisonh -> Probablility Theory (8/5/2002 11:32:25 AM)

HMSWarspite,

I am not sure what kind of math you are using to come to your conclusion.

When evaluating a distribution of probablilities, the mean is more descriptive than the median.

Given a Bernoulli varaible (outcome either Success or Failure), and each trial independent and identically distributed (same probablility distribution), we essentially have a binomial distribution. That being stated:

If repairing the a/c consists of X independent trails with a each trial resulting in a Success(a/c repaired) or Failure (a/c not repaired) given p(0.2) chance to repair, and we attempt to repair the aircraft n times, then the MEAN number of success [expected value of X or E(X)] for n attempts = n * p.

If we expect 1 a/c repaired, then n= 1/0.2 = 5 days.

I may not be a WWII naval grognard, but have studied probability theory on a graduate level.

In this case, with a mean of 1, on average, 5 attempts are neccessary to achieve 1 success given probability p=0.2.

Of course, if the probablility to repair is not independent, then this analysis falls apart.:(

May be off topic, but just dislike someone telling my my math is bad.:)



pad152 -> B17 Aircraft Transfer (8/5/2002 1:28:45 PM)

In a new game of Scen#17, I transfered B17 groups to Cooktown, it took 8 wks for all of the B17's to be transfered, because of the new rules in the patch, this sucks!!!!!!!!!!!!!. :mad: The repair rate is way off, if you transfer a group of B17s you lose up to half the group for 2 months. I aggee that B17's a little to good but, the repair rate is the wrong way to go, reduce how effective they are not the repair rate.


First mine warfare is made into more trouble then it's worth, now B17's are being made useless. I'm not happy with the way patches are going.



denisonh -> Patches Are going the Right Way (8/5/2002 2:11:54 PM)

Each patch represents progress towards a better product.

Although I find the B-17 repair rates a bit of overkill ( and it has been stated they will be relooked in the next patch), on the whole I like the patches and think they are improving the quality of the UV experience as whole.

Keep in mind the Matrix crew is busting their collective a$$es to make this the best dam WWII naval sim available.

And I appreciate their efforts greatly, because it gets better with every patch.



HMSWarspite -> Re: Probablility Theory (8/5/2002 5:24:29 PM)

[QUOTE]Originally posted by denisonh
[B]HMSWarspite,

I am not sure what kind of math you are using to come to your conclusion.[/B][/QUOTE]
Binomial prob, just as you:)

[QUOTE][B] When evaluating a distribution of probablilities, the mean is more descriptive than the median. [/B][/QUOTE]
I disagree. Take the following examples:
1, 5 a/c, repair in (days) 1,1,1,1,11. Mean=3 days, but you have 4/5 (80%) available in 1 day.
2, same 5, repair in 1,2,3,4,5 days (i.e.1 per day). Same mean, but now only 50% available after 3 days, 80% in 4.

[QUOTE][B] Given a Bernoulli varaible (outcome either Success or Failure), and each trial independent and identically distributed (same probablility distribution), we essentially have a binomial distribution. That being stated:

If repairing the a/c consists of X independent trails with a each trial resulting in a Success(a/c repaired) or Failure (a/c not repaired) given p(0.2) chance to repair, and we attempt to repair the aircraft n times, then the MEAN number of success [expected value of X or E(X)] for n attempts = n * p.[/B][/QUOTE]
With you here.

[QUOTE][B] If we expect 1 a/c repaired, then n= 1/0.2 = 5 days.[/B][/QUOTE]
Wrong. You cannot use the relationship that way.
Thats why you have to do it my way. Try it on excel or something

[QUOTE][B] I may not be a WWII naval grognard, but have studied probability theory on a graduate level.

In this case, with a mean of 1, on average, 5 attempts are neccessary to achieve 1 success given probability p=0.2.[/B][/QUOTE]
No - with a large number of attempts, you will get 1 success per 5 tries. This is NOT the same thing as each a/c will be repaired after (average) 5 attempts

[QUOTE][B] Of course, if the probablility to repair is not independent, then this analysis falls apart.:(

May be off topic, but just dislike someone telling my my math is bad.:) [/B][/QUOTE]

Agreed.;)



denisonh -> Median in Probability Distribution? (8/5/2002 10:30:06 PM)

HMSWarspite , you are right, my calculations were incorrect. This problem is not strictly a binomially distributed random variable, it is a more specific case of the binomial distribution.

If we have:
- a sequence of independent trials
- each resulting in a success or failure,
- given a constant probability from trial to trial i.e. P(i)=p for i=1,2,3,4,.....
- the experiment continues until r successes have been observed (r is a specified positive integer)

If X=number of failures that precede the rth success, this is called a negative binomial variable because the number of successes is fixed and the number of trials are random.

The expected value of X or E(X)= r(1-p)/p

For the situation in question:
r=1 (a/c successfully repaired)
p=0.2

So E(X)=1(1-0.2)/0.2 = 4

So the expected value is actually 4 days.

Source: Probability and Statistics for Engineering and the Sciences (Devore)



HMSWarspite -> (8/5/2002 10:57:57 PM)

I am interested in the lethality of bombs issue - subjectively, it feels about right, but there are folks who think it's way off. Anyone found some RL(TM) evidence for damage to armoured targets by US 500/1000pdrs?
One thing I can think is that the 'armour penetrated' result from a bomb hit doesn't literally mean that the bomb has penetrated a plate of armour like a AT round hitting a tank. It means that the bomb has defeated the ships protection scheme, and is eligable to cause extra, or critical damage. Now, this CAN mean 'punches neat hole in deck armour'. It can also mean 'hits unarmoured section, but blast/fragment/deflection gets into critical space'. It can also mean a 'near miss along side that penetrates below the belt'. (This is projecting from the game effect).

I have not found anything on the web yet about US bomb fusing. This can make a HUGE difference to bomb damage. Anyone doing better?



wpurdom -> Bomb damage to Houston and Nevada (8/6/2002 10:00:45 AM)

In the continuing saga of Dive Bomber bomb damage, I will first note the USS Houston which had an 8 inch turret knocked out, killing 57 men by a dive bomb hit on February 4, 1942.
For historical interest, I am concluding with the report of the Captain of the USS Nevada on 12/15/42 about the damage to his ship at Pearl Harbor, where from the accounts it appears that the bombs were dropped by Vals after the ship had sortied:

Damage to Nevada.

Hole in Forecastle Deck at frame 15, six feet outboard of the ship's center line to starboard, from bomb hit. Staterooms wrecked below, impossible to tell how far down the bomb traveled due to water level six feet below Forecastle Deck. Sides of trunk to paint storerooms deflected inward considerably, water fills trunk within six feet of Upper Deck. Size of hole in deck about 12 inches in diameter, just aft and to starboard of paint storeroom trunk, and aft and inboard of after starboard hawse pipe, through wearing plate.

Hole in Forecastle Deck at frame 15, 8 feet from center line of ship to port, 12 inches in diameter caused by bomb hit, depth of penetration unknown due to flooding on deck below. This hit and the hit above apparently went through to the second deck and caused fires in the Officer's Quarters. The force of the explosion also caused considerable deflection upward of the Forecastle Deck in this vicinity. On the port side, about 15 feet from the center line, the deck is split and deflected upward from frame 13 to frame 21. All of the Officer's Quarters forward of the Wardroom are either badly damaged or completely destroyed by fire. The hole is aft and to port of paint storerooms trunk, and aft and inboard of after port hawse pipe, through wearing plate.

Hole of approximately the same size as the previous two hits, about three feet in from the port waterway, frame 25. This is outboard of the anchor windlass capstans. The bomb probably went through the Wardroom to the second deck before exploding. The deck inboard of this hole is deflected upward about 4 feet and split across the center line at a point about 6 feet aft of this hole. The deck is also split aft on a direct line from this hole to frame 32, as a result of this and apparently other hits. Across the Forecastle Deck in this vicinity the entire deck from port to starboard is deflected upward considerably. The two anchor engine vertical shafts are bent forward at about an angle of 20° and the top of the capstans apparently flew upward with the deck, and hit the two outboard gun barrels of No. 1 Turret. The vertical shaft on the portside has broken away from the one coming up from below. The Main Deck in the Wardroom has been blown upward from below, and the Wardroom is a tangled mass of deck, supporting beams, and stanchions. The port skylight hatch at frame 25 has been blown partly clear of the deck wreckage.

There is some reason for believing that a much larger bomb than the ones noted previously struck the Forecastle Deck at a point ten feet to port of the ship's center line at about frame 27, just forward of No. 1 Turret, and went through to the second deck before exploding. The Forecastle Deck at about frame 29 is bent sharply downward from about three feet to port of the ship's center line to a point about 8 feet inboard of the port waterway. Due to the size of the opening in the upper deck at this point it is difficult to determine the exact outline of such a hit, but the great wreckage indicates an extremely large explosion. The forecastle is also split forward from frame 265 to frame 22 at a point 3 feet to port of the port skylight hatch. The entire forecastle deck from frame 26 is bent upward and forward to about frame 22. From the starboard side at frame 26 at a point four feet inboard of the waterway the deck is broken open and deflected upward and inboard a distance of approximately 21 feet, at which point the deck is split fore and aft from frame 23 to frame 31. At the outboard point the deck is split fore and aft from frame 25 to frame 30. The deck winch at this point was blown upward at an angle of 25°, but remained intact. The seems to be no other indications of bomb hits on the Forecastle other than the very large bomb hit or several smaller hits which apparently went through as described above. One of the reasons for being very sure that there was such a large bomb hit is the size and number of fragment holes which have penetrated the Main Deck from below at frame 25 to port of center line. Both the Wardroom and the Junior Officer's Country below appear to be completely wrecked.

Considerable damage was done by one bomb, of apparently about the same size as the two forward ones in the Forecastle, which struck the deck just forward of the port AA. director, coming down at an angle of about 30° to the perpendicular, from about 3 points forward of the port beam. This bomb continued downward through the port wing of the Navigation Bridge, and the Signal Bridge, penetrating into Casemate 6. There was no damage sustained to any part of the mast structure above the Sky Control Shack. Sky Control Shack was completely burned out, very little being salvaged from it. Sky Control deck was punctured in several places from metal fragments from below and the starboard side is badly warped from the fire below. Apparently no damage of any kind was sustained by any of the three mast supports. The only damage suffered by port AA. director, except for broken glass, appears to come from external heat, and this is very minor. The stack structure above the Boat Deck has suffered very little; mostly holes caused by an exploding 5" AA. Ammunition Ready Box at about frame 567 on the starboard side just outboard of the stack.
This bomb was apparently 12 inches in diameter, and it hit the Sky Control Deck at frame 62 port, about 6 feet outboard of a point where the port after tripod pierces the Sky Control Deck just above and outboard of the chart house. Range V (Forward Rangefinder) is apparently undamaged, but the deck aft of it is warped slightly by heat. The Navigation Bridge structure was completely burned out from below. The deck of the Navigation Bridge is deflected downward considerably at the vicinity of the wheel. There is also a burned out part of the deck inside the Navigation Bridge aft and to starboard of the forward mast support. Nothing of any value remains in the Navigation Bridge. The heat of the fire from below apparently caused the deck of the Navigation Bridge inside of the Chart House to burn completely through and fall clear leaving a hole the size of the interior of the Chart House plus about three feet further to starboard and all the way aft. The rest of the deck to starboard is badly warped, and although the starboard after tripod leg is very badly burnt externally, it does not appear to have suffered any structural damage or deflection. The starboard bridge gyro repeater and pelorous has been practically destroyed by fire. Absolutely nothing remains of the Chart House, except a partial shell. The Conning Tower structure has suffered no damage.

The bomb hit just forward of the port AA. director penetrated through the Navigation Bridge, the Signal Bridge, the Boat Deck inside of the Captain's Office and exploded on the Upper Deck inside of Casemate 6 against the forward edge of the stack, blowing a hole downward through to the Main Deck to the Officer's Galley and back to No. 2 boiler uptake. The explosion blew up through the Captain's office; and forward into No. 4 Casemate, starting a fire which spread through the Captain's quarters and up to the Signal Bridge, navigation Bridge, and Sky Control. The fire spread to the Boat Deck and set off the AA. Ready Box previously mentioned. The flag bags on the Signal Bridge were burnt out, as were the life jacket lockers. A hole of approximately 30 feet square amidships was burned in the deck of the Signal Bridge beneath and aft of the Chart house. The four compartments on the Signal Bridge were completely wrecked by fire. Nothing of value remains inside of them. Practically all of the Chart House deck hangs down through the hole in the Signal Bridge. This hole extends also through the top of the Captain's quarters and is about the same size there as on the Signal Bridge. The entire enclosure on the Boat Deck, which held all the Captain's quarters and office, was completely destroyed, mostly by the fire, and partly by the explosion from below in No. 6 Casemate. Everything of value therein has been destroyed, including all the records in the Captain's Office. A safe in the Captain's Cabin appears intact, although badly scorched on the outside.

The explosion also blew out a seam amidships of the stack on the portside for a distance about 4 feet just above the Boat Deck level; splinters were also blown through the stack from below and a number of rivets were blown out. Casualties sustained to the starboard 5" AA. Battery during action were loss of air ramming at Nos. 1, 5, and 7 AA. Guns. No. 5 was due to a rupture in the air line due to vibration. The uptake from the Officer's Galley was badly damaged by the explosion.

When the bomb struck the Upper Deck at Casemate 6, frame 65, and exploded, it ruptured the stack back as far as frame 688 port, and pushed the smoke pipe in all the way to the top. The explosion blew out the bulkhead between No. 6 & 4 Casemates, and bulged out the bulkhead to No. 3 Casemate. The Canteen was completely destroyed by fire and the explosion blew a hold overhead into the Captain's Office and Cabin. A fire was started in No. 4 and No. 6 Casemates which was extinguished before it did an excessive amount of damage. The Upper Deck in the after starboard corner of Casemate 4 was badly warped downward; hammock nettings, lockers, Canteen, and drinking fountain were destroyed. Stanchions and overhead beams in the vicinity were pulled away from the deck. Ship's Service Office was badly damaged by fire. The explosion blew back into the Incinerator Room damaging some pipe in its forward end, blowing two holes in the after bulkhead of the Incinerator Room, one particle passed through the Bakery, penetrated the Dynamo Trunk on the portside and continued through the after bulkhead of the Dynamo Trunk into the Galley.

This explosion of the bomb on the Upper Deck, Casemate 6, blew a hole about three feet square through the Main Deck in the after portside of the Officer's Galley. The Officer's Galley was wrecked; as was the Dry Cleaning Room. The after bulkhead of the Dry Cleaning Room blew back into the laundry and the port bulkhead blew out into the 6th Division living space (B-171-L). Very little damage was done in the Laundry, or living space B-171-L. Ventilation system 1-68-2 in the port forward part of the laundry was wrecked. The after bulkhead of the Officer's Galley on the starboard side was pushed back slightly into the Laundry Distribution Room. A fire main riser at frame 66 port was broken just above the upper Deck; this helped keep the fire main pressure down until it was discovered and the valve closed on the third deck. This, however, was after most of the fire had been extinguished.


A bomb hit the Boat Deck, about frame 80, just aft of the ventilator trunk to the Evaporator Room, about 12 feet to starboard of the center line (about one-half way from stack to break of the boat deck.) it apparently struck some obstruction on the Boat Deck where it appeared to have exploded, blowing a hole through the Boat Deck into the Galley and deflecting the Galley Deck downward somewhat. It is understood that there was some exposed five inch AA. ammunition laid out on the Boat Deck at this point which exploded at this time. this might account for the failure of the bomb to go deeper into the Ship. The Boat Deck was sprayed very heavily with exploding fragments which went through the after part of the stack, and ammunition hoist inboard of AA. Gun No. 7, the Evaporator Trunk Ventilator, and the Ventilators directly aft and inboard of it. Fragments also pierced the starboard forward tripod of the Main Mast, Starboard Galley, Skylight Hatch, the Deck Locker on the Steel Deck, and the fuse setter aft of No. 7 AA. Gun. Some fragments even pierced the after Search light Platform. The hole in the Boat Deck is about 12' across and 6' fore and aft. The explosion wrecked the ranges along the forward bulkhead of the Galley, and many flying fragments ruined the center table. Some pierced a few of the steel kettles, they also pierced the starboard bulkhead, and the force of the explosion deflected it outward toward No. 10 Casemate. The oil tanks on the portside were not damaged. All of the other equipment in the Galley was very badly damaged, possibly beyond repair. The explosion blew open the starboard door of the Galley in Casemate 9, starting a fire which apparently swept the entire casemate, and all of the instruments on gun No. 9 were burned up. Very little of any value is left in No. 9 Casemate. on the Main Deck inside of the Crew's Reception Room, the overhead was deflected downward from the explosion in the Galley. All the beams fore and aft were bent downward, cracked, or broken, except the one on the far port side.

There was a torpedo hit at about frame 42 port, even with the forward edge of No. 2 barbette, which tore a hole in the lower blisters A-32-V, and A-34-V. Upper blisters A-66-V and A-68-V were also ruptured. The hole was from frame 38 to frame 45 in length, and about 300 feet in depth. Another small split opening was found at about frame 36 extending about ten feet down from the second deck and about three feet in width. The explosion is believed to have penetrated the lower blisters to fuel tank A-14-F, and then to void A-426-V, to magazine A-424-M. It is believed that many compartments in the vicinity were damaged by this explosion and that practically all of the compartments forward of frame 60 and below the Main Deck are now flooded. The flooding spared aft along the second deck down into practically every compartment below the second deck so that it is believed that all the compartments except those aft of frame 122 are now flooded with the exception of certain storerooms and compartments which may have been completely water-tight.

The Engineering Department suffered few, if any, casualties from bomb or torpedo hits. Boilers are believed to be in good condition except for salting up, du to trying to keep steam up using salty feed water when the feed bottoms became contaminated by flooding from above.
The damage expected to other equipment in the machinery spaces will result from boiler priming or salt water immersion. electric wiring above the main deck is destroyed in the way of any fires. Piping is in fair condition except where actually destroyed by explosion or fragments.

SUMMARY. From the above it is apparent that the Nevada suffered at least six (6) bomb hits and one torpedo hit. It is possible that as many as ten bomb hits may have been received by the Nevada, as certain damaged areas are of sufficient size to indicate that they were struck by more than one bomb. However, direct evidence is not available to determine the exact number. The holes created. by bomb hits indicate that all, with one possible exception, were 12" in diameter (very Nearly). It is possible that all were of that size. Some may have not exploded or may have contained less explosive than others.

The damage, while considerable, should be capable of speedy repairs once the ship is afloat and alongside a dock in the Navy Yard.



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