How do you all like new v1.20 bug fixes?

[wpurdom]

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]

Originally posted by denisonh
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.

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]

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]

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]

Originally posted by denisonh
(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 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]

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]

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!!!!!!!!!!!!!. 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]

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]

Originally posted by denisonh
HMSWarspite,

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

Binomial prob, just as you:)

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

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.

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.

With you here.

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

Wrong. You cannot use the relationship that way.
Thats why you have to do it my way. Try it on excel or something

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.

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

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.

Agreed.

[denisonh]

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]

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]

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.