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mofton

Dakka Discussion - The Royal Navy 113mm/4.5in

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Good Evening All,

Prior to the release of the Royal Navy T9 and T10 destroyers, and in fact prior even to their announcement there was significant discussion as to how their main guns would function.

In game HE penetration is equal to 1/6 the caliber of the shell, and the penetration has to beat, not just equal the armor plate thickness it hits. For the RN 4.5in/113mm gun which was inevitably going to be seen on the T10, Daring this would pose a problem as 113/6 = 18.8mm (rounded to 19mm) which would not allow her to damage the hulls of T8+ destroyers with HE. With the release of IFHE this problem seemingly receded with the ‘cost’ of IFHE being 4 skillpoints.

During the balancing process as a potential sap to the requirement to spend 4 skill points on IFHE just to unlock functional guns, WG improved the Autobounce angles of the 113mm guns on Jutland and Daring. In theory this might have allowed the ships to function without IFHE, though this seems to me to not be the case, with the AP helpful, but IFHE still practically mandatory. Early CC experience has not been replicated and people rapidly got wise to the changes, while the Jutland and Daring also suffered a concealment nerf, reducing their options to 'get the jump' on other, broadsiding destroyers.

I wanted to give my views and some facts on the RN 113mm guns and how they function.

 

The Advantages of RN AP

 

The 4.5in AP has two major advantages over the AP of competing destroyers:

  1. Autobounce chance begins at 30° and is 100% at 22.5° instead of beginning at 45° and reaching 100% at 30° (with 0° being flat and 90° directly perpendicular to the broadside, see below)
  2. The 113mm AP fuses on 19mm of plating vs. 21mm for 127mm guns and 22mm for 130mm guns

These two advantages assist in passing the two biggest ‘gateways’ to a successful full AP penetration on a destroyer. There are four key gateways for any AP round to pass:

 

CTyggGJ.jpg
How AP works, in-game, ish. AP is a fairly complex mechanic compared to HE (have pen beat armor, do damage). Four basic gateways, autobounce, penetration, fuse arm and shell travel must be passed.

Autobounce is the main way a destroyer hull stops incoming destroyer-caliber AP. No T9-T10 destroyer overmatches (ignores Autobounce) any others in the matchmaking spread as overmatch is calculated as caliber/14.3 giving guns around 127mm a fairly useless overmatch value of 8mm. The RN destroyers have a significantly smaller angle range where Autobounce will occur. A normal shell will begin checking for bounce on an RNG roll at 45° increasing linearly from 0 to 100% chance at 30°. At 37.5° it reaches a 50/50 chance of Autobounce and half your shots will skitter uselessly off the target. The RN 113mm reaches a 50/50 chance of Autobounce on the other hand at about 26.25°.

Proportionately therefore the RN gun has a chance to penetrate over 75% of the possible angles it can hit at, while any other destroyer AP can only penetrate over 66% of possible angles.

TL, DR: Better Autobounce does as it says on the tin, able to penetrate over a wider range of angles.

Fuse arming is the main reason for overpenetrating destroyers with all calibers of shellfire. In WOWS every AP shell will only arm if it encounters an effective thickness of armor equal to about 1/6 its caliber.

The critical numbers for T8+ destroyers are their hull and superstructure plating, and the way that interacts with the threshold.

RN 113mm AP has a fuse arming threshold of 19mm. T8+ destroyers have 19mm hulls. Any hull hit will therefore automatically be armed. This is not the case for the larger 127mm guns which require more angle to give effective armor thickness to arm the shell – this puts a 25° zone each side of 90° in which the fuses will not arm.

T8+ destroyers have 16mm superstructures, and T7 destroyers have 16mm hulls. These do not automatically arm RN 113mm AP unless angled at least 20°. 127mm guns struggle even more requiring 41° to arm on superstructures – a narrow window before Autobounce begins.

The combined effect of autobounce and fuse arming differences is shown below:

OGqDghd.jpg  v6PDuvM.jpg

Comparative image showing net impact of the lower arming threshold and better autobounce angles on RN 113mm AP in contrast to typical 127mm AP

Fuse arming summary:

yvlqG8J.jpg

TL, DR: Hit a T8+ destroyer in the hull and the RN fuses will be armed, period. Hit the same ship with 127mm AP and flat broadside it shouldn’t arm the fuse. RN AP is also better on superstructures.

 

 

Other AP Considerations

Penetration is typically not a problem for destroyer on destroyer AP combat. At maximum range on the Daring the AP still has a penetration of 34mm.

Only when plating is angled can it generate a sufficient thickness to defeat destroyer AP, and even then the Autobounce limit also comes into effect. The ability of the RN 113mm guns to penetrate various plating thicknesses at 25° (i.e. within their RNG chance of Autobounce zone) is shown here:

 

xh7Tfj2.jpg

Effective plate thicknesses thanks to geometry for RN AP at extreme angles - at 25% you will still have a high chance of autobouncing, though typical AP will certainly bounce

If we look firstly at destroyers you can see that even at angles where there is an RNG roll for Autobounce and at considerable range, 10.3km the 113mm will penetrate the hull of a T8+ destroyer. It will also penetrate the superstructure at almost maximum range (Daring gets 12.78km stock range).

Against non-destroyers the improved Autobounce angles lose some of their value. While a regular 127mm AP round would simply Autobounce at 25°, the 113mm passes Autobounce but cannot penetrate T8+ battleship plating at that angle at ranges greater than 5.8km. Against the 50mm plating of ships such as Moskva and Khabarovsk, the improved angles have limited value at their extreme edge, but do have value in the 30°-45° zone where another destroyer would have a chance of autobouncing.

TL, DR: The raw penetration of the 113mm AP is perfectly good for DD hunting (except Khaba) out to any range you’re likely to hit with and at almost the sharpest possible angles, but leveraging the improved angles on battleship plating may be tricky.

Exploding Within the Target

 

All destroyer fuses with the exception of Le Terrible (which gets cruiser-length 0.025s) and the German ships armed with 150mm guns (also cruiser-length 0.025s) have fuse lengths of 0.01s.

In almost all cases this is fast enough to fuse within the target.

Daring and Jutland have a muzzle velocity of 746m/s. If the fuse armed immediately as the shell left the gun it would travel 7.46m before detonating. As the range increases the shell velocity drops, and the distance travelled drops too. At 5km I estimate the shell would be going <500m/s and the fuse would detonate the shell after just 5m of travel.

T8+ destroyers are pretty wide. Fatties like the Gearing have a historic beam of 12.5m. Finding ships with beams <10m is a challenge. Destroyer fuses therefore are more than adequate to ensure the shell goes off inside the target destroyer, except at the extreme bow, through the funnel etc.

TL, DR: Fuse length isn’t a big deal

 

 

 

So, Should I be Firing AP at Destroyers from my Jutland or Daring?

 

A good question. To summarize the 113mm AP and in comparison to other destroyer AP the RN ships should experience –

  • Better Autobounce angles, bouncing only when very bow/stern on
  • Automatic shell fuse arming on DD hulls T8+
  • Sufficient penetration to get through the hull even at long range (10.3km) and sharp angle (25°)
  • A fuse short enough to detonate the shell within the target almost of the time

Is this worth it?

The main drawback to the AP is that despite having better angles it is still susceptible to being bounced, especially by canny adversaries. While the angles are improved you will typically be engaging squirrely targets capable of high rates of turn. Fletcher for instance can manage a rate of turn of 8.3° per second with the helm hard over at full speed. In the 2.92s it takes your shells to reach a Fletcher the target can change heading by up to 24°, in the time it takes 2 volleys to reach the target it can almost certainly duck into Autobounce territory.

The second drawback is that AP hits to the superstructure are still relatively likely to overpenetrate.

More minor drawbacks of AP use on destroyers include a lack of fires, and while gutting the engine room is pretty productive with AP without the blast radius module damage is generally smaller.

In exchange AP does do more damage when it hits and penetrates – 693 damage per hit instead of 561, an increase of 23%.

 

Z6jtdOk.jpg
Life is like a box of chocolates...

As food for thought though, the German AP on Z-52 does double the damage of the HE – 990 to 495, and does 300 on an overpenetration.

FJW8Y9L.jpg
Shooting at 16mm plating (T7 DD hulls, and the superstructures of typical high-tier cruisers) is far less productive than shooting at the 19mm plate in the world

Theorycrafting wise not that many of your shots have to Autobounce (23%) before your HE outstrips your AP for damage. If shots overpenetrate superstructures you also lose out on damage. In a hypothetical engagement in which you land 20 hits, 20 HE shots will do (assuming no saturation) 11,220 damage. If you manage to get all 20 AP shots to land for penetration damage you do 13,860.

If however of your 20 AP hits just three autobounce and three are overpens then you produce 10,332 damage – less than you would have done firing HE and without the fire chance.

In a three or four volley engagement, shooting AP just once for autobounces may mean your effective damage drops below just shooting HE.

So, Should I be Firing AP at Cruisers and Battleships from my Jutland or Daring?

 

No more than you would from a Gearing in my view. Your sole advantage shooting at the bigger ships is your autobounce angles, and that’s a slight edge (though you’re slightly less likely to overpen the superstructure too). The combination of >32mm plating (or thicker) plus angling negates much of the advantage of your better angles, especially at moderate range. Ships with 60mm plating like Kuerfurst also resist your AP very well.  

With IFHE your fire chance is 7%, and fires on the bigger ships are worth more. A full-duration fire on a Gearing does 9% damage, or 2,061 damage – damage you could do with almost exactly three AP pens. A full-duration fire on a Montana provides 17,334 damage or about 25 full AP pens.

While fighting cruisers my one caution would be that the penetration at close range is quite poor, especially if you’re used to Lightning. At 4km the USN 5in/38 has 127mm of pen, the Lightning 140mm and the Daring/Jutland just 93mm. When high tier cruiser belts are going to be at minimum 100mm this is a pretty huge problem in the niche knife-fight scenario.

Conclusions

 

My overall conclusions (after 43 total battles in Jutland and Daring) are:

  • IFHE is entirely mandatory, people are smart enough to angle
  • Don’t be afraid to have AP selected, but if you know your opponent is going to be heading out, load HE preemptively
  • Queuing HE early in an engagement and getting a volley with 24% less damage is much better than losing a volley to bounces
  • AP is most effective at very close range where you can be more confident of landing shots into the hull
  • Not all targets work quite the same, some destroyers have less freeboard making them harder targets to tag with AP, less maneuverable destroyers which can’t change heading as fast also suffer
  • Do not shoot AP at broadsiding T7 DD’s in Jutland, the hulls don’t arm the fuse and overpens will likely occur
  • Don’t treat the guns too differently from the USN 5in/38, AP can certainly munch broadsides but the fire chance is very solid

 

Theory meets Reality

AP Gud!

dK5NzyB.jpg

In these examples the AP did a good job, and inflicts significantly more damage than the HE - in the best scenario it does manage to do more damage than the HE is even theoretically possible of - 604. The base of HE damage is never terrible, but especially in the case of Le Terrible AP kills much quicker.

AP sad!

KX02Nfp.jpg

When your AP drops below 200 damage a hit it's doing less than an overpen on average. Don't be afraid to switch. The 'floor' for HE damage in all my games has never seemed to drop below an average of about 300 damage/hit while almost zero is the limit for AP. Note that cunning bow-tanking opponents who use their turrets and saturation to soak up damage are difficult targets period.

That said, this one also suggests that firing torpedoes at DD is even less productive...

Learning Experience

fgCkLnJ.jpg

T7 DD are too easy to overpenetrate even if you do get broadsides, are frequently squirrely targets and generally deserve just beating on with HE. You have a big DPM advantage and it's typically safer to use it rather than hope you're in a fairly narrow succes range.


 

Hope you enjoyed.

 

mofton

Edited by mofton
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You put way too much effort into this one for it to just sink down the page. :Smile_great:

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Interesting read and a lot of effort Mofton.

I've defaulted back to HE (with IFHE) and only switching to AP as I would in Gearing/Z52.

 

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2 hours ago, Harv72b said:

You put way too much effort into this one for it to just sink down the page. :Smile_great:

Agreed, this must be front page news for any newbie Daring or Jutland Captain

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Excellent analysis, as always, Mofton.

Shame this isn't done by the playtesters and game developers themselves

(I guess their versions are sekrit, and therefore not open to peer review, as yours is)

O7

 

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Interesting, thanks for the effort put into this Mofton. 

I wonder, given the above, would you support an increase to the base AP damage?  In such a situation, it would reward high risk or high skill play, as well as helping with the additional 4 captain skill points it needs to be on par with other DDs.  But such a change wouldnt really affect the effectiveness of its guns against cruisers and BBs because it would so rarely be in a situation where it could directly cit them.  If so, how much?

 

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Technical posts like this should be stickied and saved for training players. No matter what level players are it gives good insight into how shells/armour interact. New players should be FORCED to learn this in training rooms!

Great post!

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Awesome information and effort provided. I will admit, I like to dumb things down to keep it manageable for my commodore 64'ish brain.....

Do I use IFHE? And should I use AP more than I normally do based on having an IFHE build?

 

Remember, without people like me, there would be no smart people. 

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Fantastic read mate! You put an amazing amount of effort into this and I learned a lot from reading it!! :cap_like:

 

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Following this post against the dim-distant future day when I have one of these ships.

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Great topic @mofton

When I face them in my Gearing I make sure to always keep a sharp angle. 

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3 hours ago, UltimateNewbie said:

Interesting, thanks for the effort put into this Mofton. 

I wonder, given the above, would you support an increase to the base AP damage?  In such a situation, it would reward high risk or high skill play, as well as helping with the additional 4 captain skill points it needs to be on par with other DDs.  But such a change wouldnt really affect the effectiveness of its guns against cruisers and BBs because it would so rarely be in a situation where it could directly cit them.  If so, how much?

 

Thanks very much!

I don't know that I would really support an AP damage increase. The HE is entirely serviceable. The AP represents a modest improvement at relatively modest risk - you have the angles and fuse arm threshold - used correctly you should do more damage, by a bit, used incorrectly damage does drop right off.

The key numbers for RN damage are 693 for AP penetration, 561 for HE penetration and 210 for an AP overpen.

In contrast for a high-AP damage ship like Z-52 it takes more effort to get an AP penetration thanks to harsher autobounce angles and the risk of overpenetrating. That said the reward is much higher at 990 for a full AP pen and the HE is pretty weak at 495 damage. The Z-52 AP is higher risk/higher reward with the exception that overpens do a reasonable amount of damage, but still not much.

Overall I think WG tried to substitute needing IFHE for the AP angles, but it doesn't really work and is a somewhat niche capability, 2,100 AP damage is reasonable.

2 hours ago, APA_204 said:

Awesome information and effort provided. I will admit, I like to dumb things down to keep it manageable for my commodore 64'ish brain.....

Do I use IFHE? And should I use AP more than I normally do based on having an IFHE build?

 

Remember, without people like me, there would be no smart people. 

IFHE - absolutely yes I recommend it

Use of AP - I would use it a bit more than a normal destroyer even with the IFHE, however if in doubt switch to HE and I usually came out of engagements thinking 'wish I'd fired more HE' rather than 'wish I'd fired more AP'.

 

3 hours ago, hipcanuck said:

Technical posts like this should be stickied and saved for training players. No matter what level players are it gives good insight into how shells/armour interact. New players should be FORCED to learn this in training rooms!

Great post!

Thanks, and to @Harv72b and @212thAttackBattalion - I might ask it be moved to RN DD discussion and stickied, General Game Discussion is higher visibility but more competitive.

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Good job! I'm still on the fence when it comes to Jutland and Daring. I might just stop at Lightning as I don't want to be forced into taking IFHE if at all possible. RPF is far too important in my mind. 

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I've been playing around with Jutland without using IFHE. 

On the one hand, the HE isn't going to actually do much damage directly... 

... but on the other hand, that's a lot of fire.

 

image.png.ffe0960da9fd3dbd26a6ee6fd74e9b30.png

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I don't even play DD's but you put so much work and detail into you post I had to say great post. 

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1 hour ago, KaptainKaybe said:

Good job! I'm still on the fence when it comes to Jutland and Daring. I might just stop at Lightning as I don't want to be forced into taking IFHE if at all possible. RPF is far too important in my mind. 

That’s my same problem. Do I want to have HE that deals direct damage or an in-game wallhack?

Choices choices. 

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g7I7cHN.gif

 

Take my upvotes!

 

I'm probably not going to get up to the 4.5" RN DDs for a while, but this information will be extremely useful when I do! Awesome analysis!

 

Given the high base fire chance (8%) the high rate of fire of the guns (24 rpm base), and the mandatory nature of IFHE, do you consider it to be better to invest points into getting back some fire chance, or is more worthwhile to invest in other abilities?

 

 

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32 minutes ago, Phoenix_jz said:

Given the high base fire chance (8%) the high rate of fire of the guns (24 rpm base), and the mandatory nature of IFHE, do you consider it to be better to invest points into getting back some fire chance, or is more worthwhile to invest in other abilities?

I don't think DE is a poor choice, but it faces a lot of competition.

With a basic IFHE build that's 14/19 points gone, you don't have much room and RDF as well would put you at 18 points if you went in that direction.

I think SE is the single most important 3 point skill to take. I'd also take AR and LS on practically any destroyer. That puts you at 16 points used.

After that I've gone with BFT, although it only increases your fire output by 10%, while DE gives you nearly 30% more, it also gives more direct damage, in particular to destroyers. Fires have always felt rather subject to the whim of RNG, what you run into, how much AP you fire etc.

SI would mostly have a purpose to give you another repair party, though the repair is pretty poor. TAE isn't worth a great deal.

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