PBY's with depth charges

[Alfred]

ORIGINAL: tacticon

First, I would like to thank Ian for the terrific example he provided. Also, AW1Steve for explanation of Aerial Depth charges. As a bonus, I drew the attention of Alfred, so I am honored.

1. I use version 26b, Scenario 1, Slot 1845 is blank. If some could provide me with the statistics or screen shot of the AC ASW device they use, I would appreciate it.

2. Since database depth charge devices have 0 in penetration and Subs have 0 armor, does that mean that penetration is not relevant when no armor is present?

3. I understand that a standard bomb is used to create an ASW device. Since effect is based on the bomb size, the only other factor is accuracy. Hydrostatic fuses must have been more accurate then contact fuses (else why use them). If the Mk9 DC gives us the upper limit acc of 30 and a 500lb GP bomb is 12, then a 250lb ASW Bomb should be somewhere between. So if we split the difference and put the accuracy at 21, am I in the ballpark?

4. This brings me to the what the expected weapon loadout would be for a Catalina. The Cats could carry 4000Lb, but It appears that they had 4 external weapon hard points. So, would 4 500lb ASW Weapons with an accuracy of 27 (spitting the difference again) be a proper loadout for a PBY flying an ASW mission? Is 27 still way too much, because that could yield one dead sub per attack?

Penetration is only a relevant input to combat algorithms which involve armour.

Just because a field exists, don't assume that the data in that field is actually used by the code or that the field heading name is correct. Fields are standardised and some data must be inputted even if the field is not used or is handed differently by the code than its name implies.

Aerial ASW combat algorithms are quite different from naval QASW combat algorithms. Don't assume that hydrostatic fuses are a relevant factor in AE.

Terminus once provided the historical PTO results which saw only 10 IJN subs directly sunk by aerial attack compared to 60 by naval action. ETO praxis and results are not relevant for the PTO and therefore AE.

Alfred

[Ian R]

ORIGINAL: tacticon


1. I use version 26b, Scenario 1, Slot 1845 is blank. If some could provide me with the statistics or screen shot of the AC ASW device they use, I would appreciate it.

Have a look at line 86 in the device database - Hopefully it will be the "600 lb ASW Bomb."

If not, the numbers are -
Type 03 - GP Bomb
upgrade - 0
side 01 - allied
available 4112
no end date
build rate, pool & range are all 0
accuracy - 28
penetration - 54
effect- 600
ceiling , armor and dud rate are all 0
anti-armor is 54
Anti-soft is 38
load cost is 600
alt device and alt use are both 0.

As discussed, this is modeled as a GP bomb, so that it works within the turn execution sequence. I think I may have borrowed it from Sid.

They do work, at least occasionally. Of the approximately 240 IJN subs of all types sunk up to mid 1946 in my current campaign (modified tier 3 ironman), 5 have been 'sunk' by Mk VII air dropped DCs, and 2 by 600lb ASW bombs. Approximately 15% of sinkings were sub v sub torpedo hits. Naval depth charges was the second biggest contributor. By far the most efficient killer of IJN subs has, however, been bombing them in port.

Looking at the sinkings list I noticed a couple of causes I hadn't seen before - "Operational casualty" and "marine casualty". Only the SSXs had that, along with groundings and hit obstructions.

And one of my BBs sunk the I2 with a 14" shell.

Sub attack near San Francisco at 216,70

Japanese Ships
SS I-2, hits 20, and is sunk

Allied Ships
LSI(M) Prince Henry, Torpedo hits 1
AM Strive
AM Champion
APA Heywood
APA Leonard Wood
APA J. Franklin Bell
APA Henry T. Allen
APA Harris
APA Wharton
AKA Procyon
AKA Arcturus
DE LeHardy
BB Oklahoma

Allied ground losses:
7 casualties reported
Squads: 0 destroyed, 1 disabled
Non Combat: 0 destroyed, 1 disabled
Engineers: 0 destroyed, 0 disabled

SS I-2 launches 2 torpedoes at LSI(M) Prince Henry
DE LeHardy attacking submerged sub ....
SS I-2 forced to surface!
DE LeHardy firing on surfaced sub ....
BB Oklahoma firing on surfaced sub ....
Sub slips beneath the waves

[fcooke]

14" shell sinking sub! Next thing you know someone will have an 18.1" nailing a PT boat! [:D]

[Ian R]

"PTxxx obliterated"

[BBfanboy]

ORIGINAL: Ian R

"PTxxx obliterated"

No, probably more like" 14" shell passes through PT boat without detonating. Portholes installed"

[BBfanboy]

ORIGINAL: fcooke

14" shell sinking sub! Next thing you know someone will have an 18.1" nailing a PT boat! [:D]

I think the Yamatos have occasionally hit a PT with their big guns, but turnabout is fair play and Greyjoy's PT nailed all nine of Yamato's 18.1" guns [magazine explodes!].

[tacticon]

Device Effect Acc Bombs Loaded Real Effect
100lb Bomb 100 5 40 200
250lb Bomb 250 12 16 480
500lb Bomb 500 25 8 1000
1000lb Bomb 1000 50 4 2000
2000lb Bomb 2000 80 2 3200
4000lb Bomb 4000 90 1 3600

Data taken from Stock Scenario 1.

My question is why a larger bomb should have a higher accuracy. I understand why a faster torpedo or a higher rate of fire for a gun would have higher accuracy. All bombs fall at relatively the same speed. Pilot skill and release altitude would also be factors, but shouldn’t these factors effect all bombs equally? I realize that the larger bomb would have a larger kill radius, but a kill radius does not double as the bomb yield doubles. There is a diminishing return on bomb’s kill radius. My guess would be that this is a balancing attribute, because the other factors in the game engine may make it too difficult to hit with larger bombs.

Using the data above, a single 4000lb bomb would be the must effective ASW device. A 12000lb Tall Boy would not have to explode, it could just land on a sub 98% of the time and just drag it under.

[Yaab]

Bomb accuracy is a non-issue, since most ASW missions set by players fly at 1000-2000 feet. At this altitude, all bombs seem to be equally accurate. But try flying any bombing mission at 10,000 feet with 100lb bombs and you will not hit a damn thing. Thus, aircraft with smaller bombs have to go lower to hit anything and face more flak in the process.

[fcooke]

It would be impressive if so, but perhaps the larger bombs are given more credit for their 'mining' effect? After all, there is a significant difference in having a 250lb bomb exploding 50' from the hull as opposed to a 4000lber. Never thought of a Tallboy as an ASW weapon, but what a weapon that would be against a poor 1000 ton sub. Or even an I-400 (what were those like 4000 tons?).

[tacticon]

Hi Yaab,

I accept your observations that small bombs are less accurate when dropped at high altitude. So, if a 5% accuracy is not cause of the inaccuracy then what is? A 100lb Bomb and a 4000lb bomb should have nearly the same free fall characteristics, with the 4000lb bomb having slightly more drag due the larger surface area. I assume that the smaller bomb would be somewhat more susceptible to cross winds due to having lower kinetic energy. I would expect that the weather variations would not effect bombs in free fall significantly unless there were thunderstorms in the hex. Weather would affect the target acquisition of the bombardier much more than the bombs free fall. That effect would still happen regardless of bomb size.

Historically, soft ground targets like troops would be attacked with a large number of small bombs because this spreads out the kill radius over a larger area. A hardened or concentrated industrial target would require a larger bomb like a 2000lb and a bunker or uboat pen would require a 4000lb bomb. It seems that the stock game uses the 500lb bomb for most mission involving level bombers. This may be how the game engine was tuned. If that is the case than using larger bombs would inflate the bomb damage too much and using bombs too small would result suppressing bomb damage too much.

Device Effect Acc Bombs Loaded Real Effect
100lb Bomb 100 0.25 40 1000
250lb Bomb 250 0.25 16 1000
500lb Bomb 500 0.25 8 1000
1000lb Bomb 1000 0.25 4 1000
2000lb Bomb 2000 0.25 2 1000
4000lb Bomb 4000 0.25 1 1000

So, what if we changed the accuracy of all bombs to 25%. Now any combination of 4000lbs worth of bombs yield the same real effect over time. 100lb bombs would still be worthless against hardened or armored targets but would more consistent in hitting soft targets. I know a lot of this is speculation and conjecture, but I would rather run this by the gallery and find out what the collective wisdom is before I waste my time running tests.

One other request, I have not been able to locate a full list of weapon filters in the forum. Can someone add any additional values to the list that Ian was kind enough to post.

[BillBrown]

Here is a link to the entire thread about aircraft load filters. https://www.matrixgames.com/forums/tm.a ... key=filter

[Ian R]

Thanks Bill, I can now explain how a calculated my Skyraider loadout filters with more precision:

2- naval (torpedo)

4 - alt naval (bombs)

17 = 1 (city attack) + 16 (port attack)

40 = 8 (ground unit attack) + 32 = (airfield attack)*

(64 = ASW , not relevant)

* Note if you do this and set them to 12k altitude, they dive bomb and release all their ordnance, including the HVSRs; it might be more gentlemanly to send then in a 1000ft.

[inqistor]

ORIGINAL: tacticon

So, what if we changed the accuracy of all bombs to 25%. Now any combination of 4000lbs worth of bombs yield the same real effect over time. 100lb bombs would still be worthless against hardened or armored targets but would more consistent in hitting soft targets. I know a lot of this is speculation and conjecture, but I would rather run this by the gallery and find out what the collective wisdom is before I waste my time running tests.

When MichelM was hunting bugs during beta, he repaired code for bombarding. From his rough description, procedure looks like this:
1. Every bomb in single plane is checked for hit, until actual hit is scored
2. Then remaining bombs are checked, until first miss
3. That ends bombarding for that plane, after first miss remaining bombs are not checked anymore
So, more bombs plane carries, the greater chance for actual hit, but not necessarily more, than ONE BOMB.

I vaguely recall my tests from years ago:
Any bomb below 250kg will probably only damage plane on airfield.
Size of bomb doesn't matter during Ground Attack. 15kg, or 800kg kill squad the same.
Damage to airfield is made by number of hits only (although I have not checked if larger bomb can score more than one hit). So obviously, more bombs the better.

And, according to manual, actual loses in fuel, and supply is calculated based on bomb effect.

[BBfanboy]

ORIGINAL: inqistor

ORIGINAL: tacticon

So, what if we changed the accuracy of all bombs to 25%. Now any combination of 4000lbs worth of bombs yield the same real effect over time. 100lb bombs would still be worthless against hardened or armored targets but would more consistent in hitting soft targets. I know a lot of this is speculation and conjecture, but I would rather run this by the gallery and find out what the collective wisdom is before I waste my time running tests.

When MichelM was hunting bugs during beta, he repaired code for bombarding. From his rough description, procedure looks like this:
1. Every bomb in single plane is checked for hit, until actual hit is scored
2. Then remaining bombs are checked, until first miss
3. That ends bombarding for that plane, after first miss remaining bombs are not checked anymore
So, more bombs plane carries, the greater chance for actual hit, but not necessarily more, than ONE BOMB.

I vaguely recall my tests from years ago:
Any bomb below 250kg will probably only damage plane on airfield.
Size of bomb doesn't matter during Ground Attack. 15kg, or 800kg kill squad the same.
Damage to airfield is made by number of hits only (although I have not checked if larger bomb can score more than one hit). So obviously, more bombs the better.

And, according to manual, actual loses in fuel, and supply is calculated based on bomb effect.

Maybe one wrinkle on the idea that more bombs is more important than larger bombs - forts. Small bombs hardly ever hit paydirt if forts are 4+, IME. Big bombs and battleship caliber shells can smash their way through some of the fort protection and cause damage/destruction. For airfields, I picture the forts as being things like revetments that isolate hits from damaging several aircraft, but if the bomb/shell can move the dirt in the wall of a revetment there is a greater chance of damaging multiple aircraft. All of this is abstracted into the weapon effect/fort damage reduction effect algorithms, of course.

[Yaab]

ORIGINAL: inqistor

ORIGINAL: tacticon

So, what if we changed the accuracy of all bombs to 25%. Now any combination of 4000lbs worth of bombs yield the same real effect over time. 100lb bombs would still be worthless against hardened or armored targets but would more consistent in hitting soft targets. I know a lot of this is speculation and conjecture, but I would rather run this by the gallery and find out what the collective wisdom is before I waste my time running tests.

When MichelM was hunting bugs during beta, he repaired code for bombarding. From his rough description, procedure looks like this:
1. Every bomb in single plane is checked for hit, until actual hit is scored
2. Then remaining bombs are checked, until first miss
3. That ends bombarding for that plane, after first miss remaining bombs are not checked anymore
So, more bombs plane carries, the greater chance for actual hit, but not necessarily more, than ONE BOMB.

I vaguely recall my tests from years ago:
Any bomb below 250kg will probably only damage plane on airfield.
Size of bomb doesn't matter during Ground Attack. 15kg, or 800kg kill squad the same.
Damage to airfield is made by number of hits only (although I have not checked if larger bomb can score more than one hit). So obviously, more bombs the better.

And, according to manual, actual loses in fuel, and supply is calculated based on bomb effect.

That would partially explain why some big bombing missions score so few hits.

I have only recently realised that the SAME number of bombers carrying the SAME number of bombs and flying at the SAME will consistenly hit/kill MORE squads in Clear weather. Go to castor troy new AAR and analyse his bombing missions against Chinese LCUs. Day after day, same bomber formations bomb the hapless Chinese. However, while Clear weather eqauls heavy losses for the Chinese, the Overcast/Moderate weather curtails the losses, while Thunderstorm weather sometimes completely reduces the losses to zero.

Now think about 100 Wirraways flying at 15,000 feet carrying 2 x 100 lb bombs in Thunderstorm weather. Since 100 lb bomb has a much lower accuracy than 500 lb bomb, and the Weather further reduces the accuracy, the MichaelM bombing code further reduces bombs' chance to hit. Thus you can have those dismal light bomber raids which never really hit anything or 2Es raids on extended range with lighter bombs which are equally ineffective.

On the other hand, if you fly against the same target in Clear weather at 2000 feet and 8 x 500 lb bombs, your bomber becomes a veritable death machine, because each bomb has now greatly augmented chance of successful hit.

I know players observed this behavior in naval attack missions, but I have never noticed the same pattern in ground attack missions against LCUs until now.

EDIT: Actually, resting your bombers in Thunderstorm weather would be optimal - you do not expend supplies for no gain and rest your pilots.