60 replies to this topic

[LC50]

Introduction

I don't claim to be an expert in WoT damage physics, but with all the discussion on HE since the 7.0 patch, I  was curious to try some actual controlled experiments and quantify damage.  Specifically I wanted to quantify the average  damage to  a KV (it used to be about 15-20% before the patch),  see if I could bounce a shot off the ground below the KV and cause splash damage (and find out how much), see if I could cause more damage by hitting the spot where the turret rubs against the hull (splash damage hitting allegedly weaker top surface of the hull), and see if splash damage to the top of the hull at the rear of the tank (engine deck) would cause more damage than hitting the hull directly.  

To do this, Montykoro and I conducted an empirical experiment  in which 48 105-mm SPH M4L23 rounds were  fired at close range (10-14 m) by an elite M4 Sherman at  an elite KV (no spall liner on the KV).  10 different aiming locations were explored to understand the damage effects of the M4's HE shell explosions.  

Many thanks to Montykoro, who patiently sat in in KV taking round after round and reporting critical hits.

I present the initial conclusions first, with all the gory details below.   I say "initial" because I don't claim to be the definitive expert  on this, and I'm sure the results will benefit from future discussions and constructive comments posted below and in other threads.  Please feel free to add your constructive comments, ideas, and questions below.  And please give Montykoro a +1 if you see him since he's such a great test subject (his KV crew needs vodka too after enduring 48 HE rounds over the course of several tedious training game sessions).  So...

General Conclusions Regarding HE

Spoiler

1.  There is no advantage to bouncing shots off the ground.  It is possible to "bounce" an HE shell explosion upwards from the ground so that it damages the underside of the hull, although the damage to the hull is not greater than  a direct hit to the side of the hull from a conventional direct hit.  Thus, there is no advantage in splashing an HE shell explosion from the ground upwards.

2.  For maximum HE damage, aim for the point low on the turret where the turret meets the hull.   It is best to land the HE shell where the explosion rays strike the most surfaces (as many have hypothesized).  Landing a shell in an area where the turret meets the hull is an optimal location to damage multiple spots at the same time.   Explosion rays striking the turret and hull will do at least as much damage as a direct hull hit  (and in some cases,  as much as 50% more).   Explosion rays striking the turret and hull definitely do more damage than a hit on the turret in a location where explosion rays are out of range of the hull (assuming turret and hull armor are the same).    

3.  Engine decks are not necessarily weaker.  The top surface of the  rear of a tank hull (engine deck) does not appear to be more susceptible to  non-penetrating HE damage than the  top of the hull on the front or sides of the tank .  This is only confirmed for the KV, other tanks may be different.

Additional Conclusions Specific to M4 Sherman Drivers that Use the 105 mm Against a KV

Spoiler

1.  Avoid side shots to the tracks.  Avoid hitting the sides of the KV tracks with HE.  The explosion rays do not appear to reach the hull.   These shots are likely only to cause 0 damage critical hits.

2.  Plan for at least 6 to 7 shots if 1-on-1.  On average (for a KV without a spall liner), HE shells cause about 16% damage to a KV.  Thus, you will need at least 6 to 7 shots to kill a KV in a 1-on-1 scenario.

3.  Facing a KV head-on may actually be for the best.  As noted above, shots landing on the lower portion of the turret will do as much damage as a direct hull shot, but, in the case of the front of the KV, you may actually do more damage (22% damage instead of 15%).  This may need more testing, though.

4.  I don't see a big HE nerf in the 7.0 patch.  [sarcasm]Feel free to disagree and keep whining[/sarcasm], but before the 7.0 patch I could get about 15-20% damage per shot on a KV.  As Thornir points out below, I have no data to back this up, so this is only my personal opinion based on my 1,000 or so games with the 105 mm.  I'm sure plenty of folks disagree and there are plenty of other forum topics where pre- vs. post-7.0 is discussed in greater detail.  It seems to be about the same in this post-7.0 experiment, or maybe a couple % less.  I may do some more testing on the effects of range on HE damage since in a recent game, I was getting less than the average 15-20% noted in my experiment (I was only 10-14 m away from target KV in the experiment).  Supposedly HE damage is not affected by range, but may be I will do some more testing if M4 drivers don't agree with the numbers from this experiment.

The Details (SCIENCE!)

Methods

Spoiler

Damage (in percent) to an elite KV without a spall liner was measured following 48 105-mm SPH M4L23 shots  fired at close range (10-14 m) by an elite M4 Sherman.  10 different locations  for shell placement (scenarios) were explored, as shown in  Figure 1.  5 shots per scenario were fired except for scenario 9, in which 3 shots were fired.  If the shot destroyed the tank, the damage was not recorded since actual damage by the shot may have exceeded that of the remaining hit points.  Critical hits were not repaired (although they were noted).  



Damage was compared among the scenarios statistically  via Analysis of Variance (ANOVA) after checking for heterogeneity of variance (Levene's and Bartlett's tests) and via the nonparametric Wilcoxon ranked test.  A posteriori means comparisons were conducted via Tukey's Honestly Significant Difference procedure.  Significance was set at an alpha level of 0.05.

Results and Discussion

Spoiler

Critical hits were scored in approximately 50% of the shots.  Shots fired into the side the hull (tracks) location failed to do any hit point (HP) damage and were excluded from all further comparisons.   All other shots resulted in HP damage, ranging from 5% to 58%.  Only one of these 43 shots (2% of the shots) penetrated the KV armor.  This shot was placed in the rear hull (scenario 4) and caused the 58% damage result.    This is surprising since the armor penetration of the 105 mm shell is only  43 and the  KS's armor in the location  hit is approximately 70 (perhaps a lucky dice roll or weak spot was hit).   The damaged caused by this hit (320 HP) was close to the +/- 25% range of the 105 mm shell damage  (410 HP).  Excluding the 58% datapoint (and Scenario 1), damaged ranged from 5% to 24%, averaging 16% per shot.

With the exception of scenario 1 (side tracks), damage did not greatly differ by scenario, as shown in Figure 2.



Figure 2 shows the average damage by scenario, with error bars representing standard deviation (SD).  No damage was observed in 5 shots to the tracks (scenario 1), indicating that the explosion did not reach the hull.  Although critical hits on tracks were noted, this is not an effective location to target.  Results from scenario 1 were excluded from statistical analysis.  

The letters above each column indicate statistical significance such that columns with the same letter are not meaningfully (statisitically) different.  For example,  scenario 6 ( A,B label) is not different than scenario 9 (A label) because both columns have an "A" label.  In contrast, Scenario 3 is different from all columns whose labels do not have a "C" (scenarios 1.5, 2, 5, 6, and 9).

Among the other results shown in Figure 2, it is clear that shots to the side of the turret away from the hull  (scenario 3: average damage 10% ) did less damage than shots to the other locations, including the same turret side at a location closer to the hull (scenario 2).  The scenario 2 shot was placed much more closely to  the hull than the shot in scenario 3, suggesting that damage rays from the explosion in scenario 2 may have penetrated the top of the KV hull instead of only the turret (as in scenario 3).  Because less explosion rays strike the hull in scenario 3, the damage is slightly less (i.e., 10% damage versus 17% damage).  However, damage in scenario 2 (side of turret near hull) was not different than in scenario 1.5 (side of hull), suggesting that the top surfaces of the hull presumably struck by explosion rays in scenario 2 are not more easily damaged than the side of the hull.  

As with the result observed for the side of the tank, the top surfaces of the rear hull (engine deck) were not more easily damaged by a shot placed on the lower portion of the turret (scenario 5) as opposed to shots placed directly into the rear hull (scenario 4).  Damage for the direct hit rear hull shots averaged 23% versus the rear turret near the hull damage of 16%.  Although, the 23% average does include the 58% damage shot that penetrated.  To enable an apples-to-apples comparison of non-penetrating HE damage, this 58% result was removed from the dataset and the statistical analysis was repeated (as shown in Figure 3).  In Figure 3 it is clear that shots on the rear turret near the hull do similar damage to the shots directly on the hull (15% versus 16%).  Thus, the top surface of the hull on the rear of the tank (engine deck) appears to be no more easily damaged than other parts of the hull.



From the above results for the sides and rear of the tank, it may be possible to conclude that there is no advantage to targeting the hull directly (scenarios 1.5 and 4) versus trying to splash damage onto the top of the hull by hitting the lower turret (scenarios 2 and 5).  Strangely enough, Figure 3 suggests the top of the hull on the front of the KV appears to be weaker (or a critical hatch or seam area is present, allowing more damage).  Damage for the lower turret on the front (scenario 9, average damage 22%) was significantly greater than damage in the lower glacis plate (front hull, scenario 8, damage 14%).  This represents nearly 50% more damage in scenario 9 than the other scenarios.  One would expect the opposite since the front turret armor is 90 mm and the hull armor is 75 mm.  

Consideing all the above results from the front, side, and rear of the tank, aiming for the lower portion of the turret is the most optimal aiming strategy, as shots that land in this area will do the same damage (sides, rear) or more damage (front) than shots landing directly on the hull.   I make no claims as to your ability to do this accurately (yes, HE is inaccurate at most battle ranges), but put the center of the recticle in this lower turret area and hope for the best.

All statistical analyses in Figures 2 and 3 indicate that one can cause damage by landing HE shells underneath the tank (scenarios 6 and 7), however, damage is no greater than shots fired directly into the front or rear hulls.  Thus, the underbelly hull is not more easily damaged by HE than other hull areas: there is no advantage to landing HE shells underneath the tank.

[ForcestormX]

Thanks for sharing! Sorry I wasn't online.

[LC50]

 ForcestormX, on Dec 25 2011 - 03:25, said:

Thanks for sharing! Sorry I wasn't online.

No problem, thanks to all who volunteered their KVs.  Montykoro was the "lucky" one that happened to be on when I had a decent chunk of time.

There may be follow-on experiments..  

[Embiggener]

Good work, but be aware that this does not apply to all big-bore HE cannons or all types of tanks they might be shooting at.  (I can think of specific examples).   It is best to take your desired shooter tank and shoot-ee tank into a training room and try things out to see what works for you.

[ForeverN00b]

It has been my experience post patch that small caliber HE rounds are a lot more affected than large caliber HE rounds.  My derp KV is still quite deadly with a well placed shot, and post patch I did over 700 damage to a tiger 1 from the side (i don't know how much it would have been, he was at 700+ HP and I finished him with that 1 shot).  The 105 mini derp cannon for the hetzer/vk2801 needs to be aimed more carefully to get maximum effect on tier6+ targets, sometimes hard to do when shooting on the move (in the case of the 2801).  Most of my other tanks I can't seem to do any damage at all with HE rounds, so outside of my KV/2801/Hetzer I roll AP exclusively now.

[Fattty]

I'm going to go out on a limb here and assume you are involved in engineering. Intro? Methods? Discussion? That says technical paper all the way.

Very very very nice. +1, or +2, hell, I'd +3 you.

[Thornir]

You lost me in your effort to come across as an unbiased researcher when you said "Feel free to disagree and keep whining"...

And then you went on to say, "but before the 7.0 patch I could get about 15-20% damage per shot on a KV. It seems to be about the same in this post-7.0 experiment, or maybe a couple % less".

You don't say WHERE you aimed, pre or post-7.0, and this "evidence" ("I could get about 15-20% damage per shot on a KV") is anecdotal. You went to all the trouble to try and make a conclusion based upon the scientific method, then resort to this.

The number of posts in all the threads on this subject that report or concur in the assertion that HE is much less effective overall post-7.0 far outnumber those that say it is not. Again, it may be more accurate physically, but in a game where little is portrayed accurately, that is of little comfort to those that have endured the compelling reduction in their ability to do damage to upper tier tanks with mid-tier tanks (and make credits,that way, as we're told we are supposed to).

People can call it a "change" if they want to, but people lost a capability they had. That is, in the context of this game, is a "nerf".

[WonderGinger]

 Fattty, on Dec 25 2011 - 04:07, said:

I'm going to go out on a limb here and assume you are involved in engineering. Intro? Methods? Discussion? That says technical paper all the way.

Very very very nice. +1, or +2, hell, I'd +3 you.

Engineering? Maybe, but for the most part it looks like stuff you'd learn in a basic Statistics class to me.

[Colin_S]

Don't really see how shooting a KV proves that HE has not been nerfed. Its the effects on the upper tiers that matter to me. At least before I could consistantly damage higher tiers for 90 - 150 damage, now its more like 0 - 90.

[Vandelay]

I've noticed that when playing artillery, I'm getting many more penetrating HE hits than I was before the patch. It seems every second match I'm hitting someone for 1400-1800 damage.

Obviously this could just be coincidence, but is there any reason why the changes to armour normalisation and HE might be causing high-calibre HE to penetrate more often?

[Ghoest]

The OP apparently never shot at a KV before the nerf.

To say their is not much difference is absurdly wrong.

Before the nerf shooting at the turret especially the lower paart of the turret ussually did over 30% damage. KVs were essentially always dead with in 4 shots if you knew how to aim.




EDIT: Im not saying the nerf was wrong BTW.  Im saying the OP is making stuff up.

[Montykoro]

Hey Any time my dear Pal!!! I like the nerd stuff!!! call me again any time!

[Stoney74]

Regardless of whether you agree with his results, THIS is how you go about proving theories for this game.  Not annecdotal crap you thought of after you had your hair up.  I'm sure the OP would like to have data from before the patch, but looks to me that he's proven (at least in the post-patch game) how to maximize the use of HE in this match-up.  Solid work and excellent documentation... +1

[Thornir]

 Stoney74, on Dec 25 2011 - 11:13, said:

Regardless of whether you agree with his results, THIS is how you go about proving theories for this game.  Not annecdotal crap you thought of after you had your hair up.  I'm sure the OP would like to have data from before the patch, but looks to me that he's proven (at least in the post-patch game) how to maximize the use of HE in this match-up.  Solid work and excellent documentation... +1

Don't agree, sorry. "Solid Research" excludes anecdotal evidence and bias. The OP has included both.

[Glythe]

How about a realistic test?

Put the same Sherman with the 105 against a KT starting at point blank range (10m).

Try to reproduce the damage you could inflict before the 7.0 patch.

And then try to get some shots from around 100 to 200 meters which is a far more realistic engagement range.  


If you prefer you could run the same test with a kv derping against any non-American tier 9 heavy.

[Reklaw]

You seemed to understand what you were talking about up until your "feel free to keep whining" part. No, HE's damage has not gone down. The mechanics have changed. Of course you can do the same damage to a KV as you could before. The damage hasn't gone down. The way HE finds places to do that damage has changed. When people say HE has gotten worse, they're talking about its mechanics, not its damage. HE has a harder time reaching its maximum damage because of how it hits its targets. It's more difficult to strike critical areas. You'd know this if you weren't doing a controlled experiment where you got within a few meters of a target that wasn't firing back at you and landing hits wherever you wanted.

[Fresco26]

You really want to know why HE got nerf? Simple its due to the French Tree. Those tanks have about the weakest armor. If HE would of stayed the same any tier tank would of been having a field day destroying all the French tanks. Considering a Tier 3 US TD can do 400 damage to a tier 10 French Heavy..It's why HE had to get a overhaul to be less effective on the French Line...

[Altruismo]

Mate, I'm stalking you for a month to give you all my +1's.
Not only have you demonstrated that it is still possible to deliver comparable HE damage to pre-patch, but you've also shown that the way to do it is, really, the way people should always have been firing their HE.

Put the shell as close as you can to the thinnest armour on the tank.

The thing that amazes me the most about all the post patch HE backlash, is that so many people seem to think this is an unreasonable expectation.

[Ghoest]

 Altruismo, on Dec 26 2011 - 00:54, said:

Mate, I'm stalking you for a month to give you all my +1's.
Not only have you demonstrated that it is still possible to deliver comparable HE damage to pre-patch, but you've also shown that the way to do it is, really, the way people should always have been firing their HE.

Put the shell as close as you can to the thinnest armour on the tank.

The thing that amazes me the most about all the post patch HE backlash, is that so many people seem to think this is an unreasonable expectation.

He did not demonstrate that at all. Stop lying.

He demonstrated what the they currently do.

It used to be that a 105 that aimined at the right spots made a mockery of the KV1.
It would be totally reasonable to say the old situation was unfair - but its total lie to say the cuurent situation is comparable to the old one.

Go be a liar somewhere else.

[Nichts]

ITT: One person who understands what's happened to HE post-0.7.0, and lots of people who either don't understand or don't want to understand.

Very well done OP. Don't be discouraged by the people posting here... they'll argue til they're blue in the face if you don't prove their point, no matter how many times they are shown to be wrong.