DaBabes AAA Tweak Info?

[Nemo121]

Would it be possible for someone to walk us through the methodology underlying the DaBabes AAA tweaks. I'd be interested in seeing if these tweaks would be useful in an EA mod but, obviously, while it looks good from what I've seen I'd like to get a feel for the underlying assumptions etc so as to make a better judgement.

[JWE]

First thing is all the numbers have to be in about the same range as what’s there already. The code wants to see a certain range of values.
Next thing is the numbers have to line up with the numbers for weapons that can’t be changed because their data is used in other places, like DP guns.
And then the numbers have to reflect some kind of rational relationship of the effectiveness of one weapon vs the others. Those are the constraints of the box.
We made “effectiveness” be a measure of the raw mass of metal and calculated amount of bang that could be hosed from a self-loading, automatic weapon.

Start by getting the projectile weight and the bursting charge fill (if applicable) for every weapon in the inventory; and every one is different, even the 40mm/2pdrs are all different. Here’s what it looks like for a few of the high volume weapons. Pick one as a base; we picked the Japanese 25mm. Express the Wt and the Fill as a ratio of the 25mm values. For 37mm and above, the Fill Equivalent is the SQRT of the Fill Ratio, for the rest, Fill Equivalent is Fill Ratio. Weight Equivalent remains the same as Weight Ratio.
-- -- -- -- Proj -- -- Fill -- -- Wt. --- Fill -- -- Fill
-- -- -- -- Wt. -- -- Wt. -- -- Eq. --- Ratio -- Eq.
25mm -- .550lb -- .020lb -- 1.00 -- 1.00 -- 1.00
20mm -- 0.27lb -- .014lb -- 0.49 -- 0.84 -- 0.84
1.1 in -- 0.92lb -- .035lb -- 1.67 -- 1.75 -- 1.75
40mm --- 2.0lb -- .150lb -- 3.64 -- 7.50 -- 2.74

Then multiply Wt. Eq. and Fill Eq. by “Practical/Actual/Effective” RoF. Divide by 10 to put the decimal in the right place. The results look like this.
-- -- -- kRoF -- WE -- -- FE -- -- kWF -- -- Eff
25mm -- 11 -- 11.00 -- 11.00 -- 11.00 -- 22
20mm -- 25 -- 12.25 -- 21.00 -- 15.17 -- 30
1.1 in -- 10 -- 16.70 -- 17.50 -- 16.97 -- 34
40mm -- 11 -- 40.04 -- 30.14 -- 33.44 – 67

For 37mm and above, kWF is (2FE + WE)/3. Below 37mm, kWF is (2WE + FE)/3. Eff is just kWF x 2, since the Bofors wants to line up with a 5in/38, which has Eff of 52, so 67 isn’t bad. When you are all done, it looks something like this, except there’s about 20 more entries.

[stuman]

Thanks for the attention to detail JWE. I am glad that you like to keep tweaking the game for us.

[witpqs]

What does the "k" in kRoF and kWF stand for?

[JWE]

ORIGINAL: witpqs
What does the "k" in kRoF and kWF stand for?

It's just a silly math thing. It just means "function of".

[witpqs]

Thanks - heck, I remember that as f as in f(x).

[Nemo121]

Interesting, sounds like a good mathematical basis.

My understanding is that DP guns and larger guns ( ?more than 40mm in size ) were excluded from the reconsideration. I understand the need to exclude DP guns but I was curious as to the cut-off point and why it was cut off at that point.

Would I be right in thinking that a 25mm Triple Mount would then have a AAA rating of 66, almost as good as the 40mm USN mount. Which is a very interesting finding indeed.

Question though, wouldn't a 40mm Bofors mount ( with some 4 barrels ) have a AAA rating of 264? Which makes the 25mm Triple mount seem a lot less impressive .

[JuanG]

Pretty sure these are all 'per barrel' ie for one device. A quad mount is 4 such devices.

As for why DP etc guns were left out, I suppose the reasons is because they are more directly involved in Surface Combat routines too, and so any major changes might throw things out of whack there (I seem to remember a case of 'laser guided' 5in/38's when AE was first released due to the accuracy values carried over from WitP).

Thanks for explaining this, means I wont have to bang my head against a wall trying to figure out where any ahistorical weapons I add fit in.

The one thing that seems off is the 2pdr vs the 40mm. As far as I remember, USN experiments concluded the early (low velocity) 2pdr was at best 50% as effective as the 40mm vs torpedo bombers, though almost as good vs kamikazes. The high velocity version was better, but still not equal to the Bofors. Yet from the values in DBB it would seem the 2pdr (unspecified as to which) is as good or better than the 40mm.

[witpqs]

Remember the range of each gun, too.

[Nemo121]

JuanG are you comparing 4-barreled 2 pounder mounts with the 4-barrelled 40mm mounts though?

Per barrel it might be as good but perhaps the number of barrels per mount might be the difference?

[Nemo121]

One other question though...

Wouldn't this make PTs ( which might use 40mm and 25mm mounts as their main weaponry ) even more devastating vs light targets ( such as DDs ) ?

[Mifune]

Good questions Nemo.

[JuanG]

ORIGINAL: Nemo121

JuanG are you comparing 4-barreled 2 pounder mounts with the 4-barrelled 40mm mounts though?

Per barrel it might be as good but perhaps the number of barrels per mount might be the difference?

Im looking at them on a barrel to barrel basis, and so even if we consider a quad 2pdr and a quad 40mm, the situation is the same; the 2pdr is superior to the 40mm. I did some tinkering with these values and dropped 2pdr range and ceiling some, and dropped the accuracy into the 60s - this seems to give more reasonable results; the 2pdr is just as lethal to anything it hits, but it wont hit that often.

ORIGINAL: Nemo121

One other question though...

Wouldn't this make PTs ( which might use 40mm and 25mm mounts as their main weaponry ) even more devastating vs light targets ( such as DDs ) ?

This is one thing I'm worried about too, and I intend to run some tests to see just how bad it is; I dont really mind a single 40mm starting fires etc on small ships or DDs, but sinking them should be hard.

[witpqs]

I presume a code fix is next to impossible considering the maintenance/bug fix state of AE. Even still, if the 40mm turns out to be a problem for surface engagements then perhaps the developers can get a code fix through. It would also help other DP guns like the various 3 to 5" classes and would be a major fix to a functionality issue.

Let's see how this goes. If PT's get too deadly I'll reduce my use of them even more. One thing, though, PT's would be even more vulnerable to, say, 25mm fire, so this might not be a problem at all. It might even turn out to be an improvement. We'll have to see how things perform.

[Nemo121]

witpqs,

The problem isn't so much that PTs wouldn't be vulnerable. The problem is about relative potentials across weight classes rather than within weight classes. Here's an example of what I mean:

Let us assume that the 40mm USN gun and 25mm IJN mount are both increased in power by a factor of 4.
The RELATIVE combat power of the IJN and USN PT boats will still be the same. If USN PTs had double the firepower they'll still have double the firepower.


BUT the relative combat power of IJN and USN PT boats vs USN and IJN DDs will have shifted greatly because the majority of the gunpower of USN/IJN PTs lies in these small calibre guns ( 25 to 40mm ) which have gotten increase in power by a factor of 4 while the USN/IJN DDs have the majority of their combat power in larger guns ( 5 inch guns etc ) which do NOT have any shift in their combat power.

Essentially USN and IJN PTs may have just become 4 times more deadly in gun combat while USN and IJN DDs ( which derive more of their firepower from 5 inch guns than sub-40mm guns ) may only have had their surface gunpower increased by 50%.


My question is whether this gain in AAA power is really worth it if the cost is making PTs on both sides even more deadly vs DDs.



The fix would obviously be a code fix which separated out surface combat power from AA combat power for these DP weapons but since that hasn't happened yet I doubt it is going to happen now.

So we're stuck with a situation where these changes seem much more historical and to be applauded but may have unanticipated consequences particularly in terms of the relative surface combat power of small boats ( PTs) vs DDs/AKs etc giving the PT boats an unwarranted boost which may make this - some would say already overpowered unit - even more lethal. This situation is binary, while the AAA realism is applauded it only comes at the cost of the impact on surface unit combat. We either take both or neither but without a code fix we can't pick and choose, which is unfortunate.


Maybe the DaBigBabes team have tested the outcome of this in PT vs DD combat though? PT vs PT combat will be relatively shifted in a proportional manner so isn't the right thing to test, we need to test all-sub 40mm units vs mostly large gun units ( DDs) in order to check the effects of the differential, non-relative boosting of overal gun combat power.

[witpqs]

I understand.

We should first get a look at some results and see how it's working in practice.

If it is a problem, there is an alternative to a code fix. The PT's could be given different 40mm (and/or other) devices instead of the same ones used by other ships (and that has reduced stats). This could be justified because PT's are not as stable gun platforms as larger ships, therefore can't be expected to perform AA as well.

[herwin]

Once upon a time, I did an analysis of WWII naval AA systems taking into account maximum effective range, minimum effective range, sustained rate of fire, shell burst radius (treated as effective target radius if non-bursting, and scaled based on energy transferred to the aircraft), and fuzing. My sources were unclassified if they were friendly, and declassified for the Japanese, Germans, Italians, and Soviets. Results calibrated based on the open source OR literature available at the time. You have much more data, but the following figures should be a rough order of magnitude for comparison. These are expected aircraft shot down from a single wave attack by one barrel under director control. An equal number of aircraft would be damaged. BTW, the effect on bombing accuracy is marked, even if the guns are under local control.

Br 5.25": 0.22-0.25
Br 4.7": 0.135
Br 4.5": 0.2
Br 4" (1916): 0.1
Br 4" (1920s): 0.125
Br 4" (1935): 0.195
Br 2lb: 0.065
Br 3" (1914): 0.075
US 5"L25: 0.11
US 5"L38: 0.25
All 40mm: 0.06
US 1.1": 0.03
All 20mm: 0.045
US 3" (old): 0.04
US 3" (DP): 0.1
US 3" (1944): 0.2
IJN 5"L50 HA: 0.2-0.225
IJN 4.7" HA: 0.125
IJN 3.9": 0.25
IJN 25mm: 0.025
Ger 105mm: 0.25
Ger 88mm: 0.155
Ger 20mm: 0.045

Triple for VT fuzing.

[Nemo121]

Herwin,

I'm assuming that data wasn't corrected for plane type though was it?

E.g. It would be a lot easier for a USN 40mm mount to take down an unarmoured Kate than for an IJN 25mm mount to take down an armoured Avenger....

[herwin]

ORIGINAL: Nemo121

Herwin,

I'm assuming that data wasn't corrected for plane type though was it?

E.g. It would be a lot easier for a USN 40mm mount to take down an unarmoured Kate than for an IJN 25mm mount to take down an armoured Avenger....

It was calibrated against IJN carrier aircraft. For the most part, it didn't matter much because the kill mechanism used in the analysis was airframe damage, not pilot/crew/engine casualty. Armour helped for small calibre fire and the like, but having a 5" shell detonate within its lethal radius of you was a really hurtful experience. Ditto for a machine cannon that got your range and bearing and dumped a lot of explosive shells into you. Those 25mm cannon, though, were pretty pathetic.

[JohnDillworth]

This is great work but I sure hope someone address the 5" DP guns. I believe they are the backbone of the AA defense for the Allies and they increase in value the later in the war the game goes. Right now they are pretty useless, even in 45. Essentially the game discounts proximity fuses and radar directed fire. Bot of which got progressively better and more numerous. Definitely on the of the biggest remaining flaws in an other wise excellent game.