Japanese destroyer upgrades

[cardas]

Aircraft attacking ships can be attacked by shipborne AA guns in three different phases;

1. Approach
2. Attack
3. Outbound

The first and third phase is done at the set altitude of the air group and so is the second (attack) phase if level bombing. In case of TBs the attack phase is at 200 feet, dive bombing at 1000-4000 feet and glide bombing at 2000-5000 feet.

In the attack phase only the ship being attacked fires its AA guns. On the approach and outbound phase guns from all ships in the TF can fire if the altitude is within the ceiling of the AA gun. Unknown penalties due to TF size applies.

So yes, 25 mm guns are useless for fleet defence unless your opponent is sending in groups at a very low altitude.

There's a post about this somewhere if you search around.

[geoffreyg]

Many thanks Cardas - very clear exposition.
The 12/43 Yugumo upgrade in Scenario 1 stock loses 2 x 12.7cm DP's in return for more 25mm plus surface radar.
In December 1943 the Japanese have many good ASW vessels that can screen CV's.
Would this lead to the conclusion that one should not upgrade the Yugumo's then but wait until the 9/44 upgrade when they gain air radar?

[rustysi]

Ahem, there are other factors here which we seem to be forgetting. As mentioned above, the surface search radar and upgraded DC's for these Japanese DD's. IMHO these DC upgrades are important as they come about the same time that the US torps are improving. Subs are a real threat and ASW if neglected is at your own peril. I'll state again, let the fighters defend the air while the DD's defend the depths. Besides all said and done Japanese AAA is nothing compared to what they will face against the US surface vessels. Of course JMHO, even if strongly stated.

[Lowpe]

I go for the upgrades. Radar and the depth charges are too nice. A few extra dp guns among your destroyers won't stop the Allies but a few more minutes warning on the air raid can be really significant. I do like the CLAA upgrade for Tenryu though...and I think every JFB needs to stuff the KB with as much AA you possibly can I just feel radar is much more important.

This was discussed at length in Captain Crufts Hive AAR, where he wanted to not do the upgrades for the destroyers that lost torpedo tubes. Given his planned tactics, I think the correct decision for his game. Unfortunately, the game ended prior to finding out how well his wall of torpedoes would have done.

[geoffreyg]

I don't disagree with the generality of the foregoing helpful comments but when one is looking at the 12/43 upgrades to the Yugumo's one loses (in Scenario 1 stock) 2 x 12.7cm DP's in return for more not very useful 25mm plus surface radar. Air radar does not arrive until the 9/44 upgrade which does look worth doing.
As mentioned in December 1943 the Japanese have many good ASW vessels that can screen CV's including the lovely Akitsuki's which are all round great.
I continue to lean towards waiting for the 9/44 upgrade.

[PaxMondo]

Not disagreeing with anything here, but the 12.7 DP's shouldn't be DP, that's an easter egg from the Dev's. The 12.7's couldn't be loaded with the barrels above 15 degree elevation (or something like that). So to fire an AA round, they had to be fully depressed before reloading ... not really a DP in my book. ROF is like 5/minute ... the IJN 100/65 or 80/60 were truly DP's. ROF's were +20/min at essentially any elevation.

[Dili]

Precisely. In the game they seem almost or better(more effect) than 100mm of Akizuki class. Does not make sense.

[rustysi]

I do like the CLAA upgrade for Tenryu though

Yup, and there are some other CL's which can upgrade to CLAA's later.

I think every JFB needs to stuff the KB with as much AA you possibly can

Pretty much goes without saying.

I just feel radar is much more important

By the time the DD's start getting air search radar, all Japanese CV's should already have it. I, on the other hand like the surface radar as I feel it should help with the DL on enemy subs.

Pax, thanks. Good points. I hadn't realized those guns were not really DP's.

[geoffreyg]

I think I would concur that the Yugumo 12.7cm's are a touch flattered by being classed as DP - however I take the view that you have to take the smooth with the rough when looking at the WITP-AE database.
On another related point the Agano's twin 15cm guns are shown as having a ceiling in tracker although not classed as DP. I assume this implies they have some AA capability although as I think they dated from 1912 I would find that somewhat doubtful!

[wolfe69]

Type 95 DC are useless lol, not really they are good. Depending on the ship crew's experience and the captain. I manage to sink a American sub in deep water and very nasty in shallow waters as well. As long you have good detection levels, crew's experience and the right hardware, you will do something nasty.

[Grfin Zeppelin]

ORIGINAL: wolfe69

Type 95 DC are useless lol, not really they are good. Depending on the ship crew's experience and the captain. I manage to sink a American sub in deep water and very nasty in shallow waters as well. As long you have good detection levels, crew's experience and the right hardware, you will do something nasty.

Oh sure, they get results once in a blue moon but I would really not call the good.

[obvert]

Been reading with interest here. Love the different thoughts about how to use the IJN DDs best.

I've done both, upgrading and not. Still not sure what the effects are as the Allies are just tough all around in the endgame.

My main question here is how much do the air radars accumulate? If the CVs have them, the cruisers have them, the BBs have them, do the DDs also need them? We're never talking about sending the DDs out alone hoping they'll vector CAP in to their defence, right? This is for the KB mostly, which could be loaded with 20+ radar sets once they're available, especially since the late war CVs all come with a bunch. Maybe SCTFs with LR CAP, but those could still have 4-5.

The late CVs have 4 x air radar sets!! [X(]

Many of the BBs have 2 x air radar, and the cruisers have one too.

So if you have (for example) 4 x Unryu class CV, 1 x Kongo, 1 x Tone and 8 DDs (not upgraded) you still have 19 radar sets. Are more than that needed? [&:]

[Barb]

I would say that every radar set available is good.
Given their range they contribute to the success of detecting incoming air raid. With the "Effect" (actually chance to detect) of Japanese radars in range of 40-60% this actually mean that about half of the devices would actually detect the raid. The more detection the higher detection level. The greater the distance, the more time to get CAP in place.

It is another case with allied radar sets working with 80-100% effectiveness. But even there, the more the better.

[obvert]

ORIGINAL: Barb

I would say that every radar set available is good.
Given their range they contribute to the success of detecting incoming air raid. With the "Effect" (actually chance to detect) of Japanese radars in range of 40-60% this actually mean that about half of the devices would actually detect the raid. The more detection the higher detection level. The greater the distance, the more time to get CAP in place.

It is another case with allied radar sets working with 80-100% effectiveness. But even there, the more the better.

Are we sure that once you get over 10 sets it will really make a big difference?

On the ground if I have 3-4 sets operational that makes a huge difference. If 20 sets on the KB detect at even 40%, the odds are great that the raid will be detected 100% of the time. The odds are also that it will be detected at full range if 1 of the 8 detecting sets see them at full detection range.

So the question for me would be do the other "lost" positives of having the 33% more 12.7mm DP guns outweigh any benefit from radar when in the most likely formation to need that radar in the late game? I'd wonder if the extra 12-16 12.7mm DP guns would make more of a difference in defending an air strike than the extra radars on those DDs. Isn't that effectively two CLAA worth of the most effective AA you lose doing the conversions?

The DC racks going to Type 2 is critical against the late war USN subs, though so that is also a factor. You'd want the Akitsukis and Yugumos there with Type 2 DCs for sure even if you didn't convert Kageros, Fubukis, etc.

[Lowpe]

I think Barb has got this correct. Obvert can always do a test in our new game...strip his carrier TF's of half their radar sets and we will see what happens.[;)]

Just read Obvert's post and you are thinking binary: the radar works or it doesn't. I think it is my experience that extra radar sets are additive to the warning time and not on/off.

Of course I could be all wrong.

[obvert]

ORIGINAL: Lowpe

I think Barb has got this correct. Obvert can always do a test in our new game...strip his carrier TF's of half their radar sets and we will see what happens.[;)]

As with CAP and sweep stuff, conjecture is really fun, but unless we see it in tests do we really know?

I'll make sure to do that with my CVs. Really I will. So come late 43 just roll the KB into range and we'll see what happens! [:D]

[rustysi]

Been reading with interest here. Love the different thoughts about how to use the IJN DDs best.

I've done both, upgrading and not. Still not sure what the effects are as the Allies are just tough all around in the endgame.

My main question here is how much do the air radars accumulate? If the CVs have them, the cruisers have them, the BBs have them, do the DDs also need them? We're never talking about sending the DDs out alone hoping they'll vector CAP in to their defence, right? This is for the KB mostly, which could be loaded with 20+ radar sets once they're available, especially since the late war CVs all come with a bunch. Maybe SCTFs with LR CAP, but those could still have 4-5.

The late CVs have 4 x air radar sets!!

Many of the BBs have 2 x air radar, and the cruisers have one too.

So if you have (for example) 4 x Unryu class CV, 1 x Kongo, 1 x Tone and 8 DDs (not upgraded) you still have 19 radar sets. Are more than that needed?

When it comes to the point I'm trying to make here you are comparing apples to oranges. In addition to the type 2 DC's the radar that is added is a surface radar, range of 37k IIRC. What I'm pointing out here is that this should help raise the DL on subs, thus increasing the likelihood of an attack. It is these radar that I'm interested in acquiring, not more air search radar. Although my thoughts are the more the merrier, especially when it comes to Japan. I just know that even if there is a remote possibility that a dozen radar sets will fail to detect a raid it'll happen to me. That dark cloud has been there all my life.[:D]

[obvert]

ORIGINAL: rustysi

Been reading with interest here. Love the different thoughts about how to use the IJN DDs best.

I've done both, upgrading and not. Still not sure what the effects are as the Allies are just tough all around in the endgame.

My main question here is how much do the air radars accumulate? If the CVs have them, the cruisers have them, the BBs have them, do the DDs also need them? We're never talking about sending the DDs out alone hoping they'll vector CAP in to their defence, right? This is for the KB mostly, which could be loaded with 20+ radar sets once they're available, especially since the late war CVs all come with a bunch. Maybe SCTFs with LR CAP, but those could still have 4-5.

The late CVs have 4 x air radar sets!!

Many of the BBs have 2 x air radar, and the cruisers have one too.

So if you have (for example) 4 x Unryu class CV, 1 x Kongo, 1 x Tone and 8 DDs (not upgraded) you still have 19 radar sets. Are more than that needed?

When it comes to the point I'm trying to make here you are comparing apples to oranges. In addition to the type 2 DC's the radar that is added is a surface radar, range of 37k IIRC. What I'm pointing out here is that this should help raise the DL on subs, thus increasing the likelihood of an attack. It is these radar that I'm interested in acquiring, not more air search radar. Although my thoughts are the more the merrier, especially when it comes to Japan. I just know that even if there is a remote possibility that a dozen radar sets will fail to detect a raid it'll happen to me. That dark cloud has been there all my life.[:D]

I hear you , and the sub detection is surely better with the Type 2 and radar. Not apples to oranges, just that apples, oranges and bananas are all available, and you only have a certain amount of cash, so which are you going to buy! [;)]