Question: Why are autobounce angles in the game?

[SyndicatedINC]

This is an honest question, that I have looked around for awhile now and never heard a concise answer.  I am hoping that perhaps someone from alpha or closed beta may know.  Why did WG implement an autobounce angle mechanic instead of just using the armor thickness as calculated by the angle of impact the shell comes from to determine as other games have done?  Was this to reduce calculations for the server (is that really more complex to calculate than the autobounce angle as currently)?  Was it a balancing decision to prevent certain ships/shells from penning certain sections with moderately angled plunging fire?  

 

Again this isn't a complaint thread, just an "I am curious and can't find the answer elsewhere" thread.  Does anyone here know the reason that it is implemented in game as such?  Every time I am teaching a new player about the game I dread explaining autobounce as invariably they ask "why is it that way" and I have no answer other than "because it is".

[RipNuN2]

This would be why . . . 

 

[LittleWhiteMouse]

Because they're a very real thing in ballistics.  The autobounce mechanics are just a rough approximation of what occurs with actual shells.

[BrushWolf]

7 minutes ago, LittleWhiteMouse said:

Because they're a very real thing in ballistics.  The autobounce mechanics are just a rough approximation of what occurs with actual shells.

This, as the angle gets shallower the effective armor thickness increases until the shell cannot penetrate.

 

Edit: I just noticed that you can remove your upvotes.

[Cruxdei]

physics magic,sometimes autobounce in real life just melt my mind.

[LittleWhiteMouse]

Don't take my word for it.  Here it is from navweaps.

"Oblique impact was ignored by most of the earlier of these formulae because the projectiles were not very well designed for handling the sideways forces caused by such impacts and had considerable variation in penetration ability from test to test due to projectile deformation and breakage in various unpredictable ways. This problem remained true when attacking face-hardened armor using some of the weaker projectile designs even through the end of WWII, but by then it had mostly been solved by improved projectile designs and metallurgical expertise.

"Oblique impact is rather complex. Below the projectile's "biting" angle (the highest obliquity where nose-first penetration occurs at the Navy Ballistic Limit with this projectile against all thicknesses of the plate type under test), for a given plate type thickness does not significantly affect the percentage increase in striking velocity required to penetrate at a given angle compared to penetrating the same plate at normal (a single multiplier for a given obliquity gives good results for all plate thicknesses where projectile damage is not changing things). The projectile's nose immediately digs into the plate and inhibits ricochet. However, projectiles that impact plates at above their biting angle will have their noses pushed strongly away from the plate, so they will rotate in the direction parallel to the plate face and try to push through the plate sideways, which causes a considerable increase in the required energy to penetrate due to the larger hole needed and the loss of concentrated impact force on the plate at the point of initial impact as the nose skids sideways on the plate surface. Above the biting angle, increasing plate thickness drastically increases the required energy to penetrate until any sideways penetrations are essentially impossible for thick plates. When this occurs for a thick plate, it is necessary to increase the striking velocity even more to the point where a nose-first penetration can be obtained at the Navy Ballistic Limit (similar to below the biting angle, but requiring much more energy to accomplish), but to do this requires that the projectile dig into the plate so deeply on the initial impact that the nose is caught by the mound of armor material pushed up in front of it (no mound can form with face-hardened armor, but the nose can dig into the hard material at the far side of the hole after punching out a plug) and held until the glancing rotation of the projectile ceases when the base hits the plate's surface. The very large increase in striking velocity needed at high obliquity for complete penetration is essentially impossible above about 75-80^o even for thin plates when pointed projectiles are used, though brittle plates can have plugs of armor punched out of them by the impact that can cause severe damage by themselves (especially a problem with face-hardened armor).

"At high obliquity, interestingly enough, projectile damage that breaks a projectile (not just bends it, which is always bad) can help penetration, since the ricochet of the nose does not pull the entire projectile away with it and at least some of the lower body of the projectile can sometimes penetrate through the tear made in the plate by the nose before it bounced off. This is especially a problem with face-hardened armor, where a high-obliquity impact can punch out a large plug of armor, resulting in a large elongated hole, even when the projectile itself has no possibility of penetration unless it snaps apart and its lower body can pass through the hole it just made. Unfortunately for the target of such an impact, face-hardened armor is designed to cause such projectile damage on purpose and will thus enhance rather than reduce the damage to the ship compared to the use of ductile, homogeneous armor under such highly oblique impact conditions (as if the punched-out plug of face-hardened armor flying around wasn't bad enough!)."

World of Warships used to simulate some of the kinetic damage caused by non-penetrations by having shells that shattered or bounced off inflict a small (approximately 1% to 2%) shell damage.  This was removed in the early stages of Closed Beta with the overhaul to AP and HE shell mechanics.

[SyndicatedINC]

It would appear that I wasn't clear enough in my question.  I am not asking why shells can bounce.  I am asking why do we have the specific arbitrary degrees of angle that make up autobounce instead of the actual ballistics of the shell versus the armor thickness at the angle of impact.   As both means of calculation would produce bounces still, why did WG create a new means of calculating it as they did? 

[LittleWhiteMouse]

Just now, SyndicatedINC said:

It would appear that I wasn't clear enough in my question.  I am not asking why shells can bounce.  I am asking why do we have the specific arbitrary degrees of angle that make up autobounce instead of the actual ballistics of the shell versus the armor thickness at the angle of impact.   As both means of calculation would produce bounces still, why did WG create a new means of calculating it as they did? 

I imagine it has something to do with the "biting angle" mentioned in that navweaps quotation. 

 

 

[SyndicatedINC]

1 minute ago, LittleWhiteMouse said:

I imagine it has something to do with the "biting angle" mentioned in that navweaps quotation. 

 

 

I can understand that, but still doesn't it seem odd, as the biting angle for many shells versus the surface they impact is better than the 30 and 45 degree marks to which they autobounce right now?  I mean why choose those specific angle bands?

 

*shrug* It just seems like there is something more to it, like balancing purposes, or some such.  So many other aspects of the game are so much more in depth under-the-hood in terms of mechanics, it seems odd they just veered off complex realism to arbitrary bands of angles for no reason.  Again not complaining, I am fine with the mechanics as they are, just wish I knew why they are this way and not more realistic.  Figured like so much else there was a good story behind it, and was hoping to learn that story.

[Jinxed_Katajainen]

18 minutes ago, SyndicatedINC said:

It would appear that I wasn't clear enough in my question.  I am not asking why shells can bounce.  I am asking why do we have the specific arbitrary degrees of angle that make up autobounce instead of the actual ballistics of the shell versus the armor thickness at the angle of impact.   As both means of calculation would produce bounces still, why did WG create a new means of calculating it as they did? 

Think it's just to keep everything simple and uniform.  Since the game doesn't take into account any details like armor quality or type and shell quality and type, it's just calculated as a slab of armor vs a shell coming in at x angle.

Honestly, it's much better as a game since there's no need to remember things like what an IJN Type 91 shell would do against a slab of Vickers Non cemented vs Wotan vs Class A, etc... just your AP shell will bounce if it hits at x degrees.  Also gives a point to work from when considering overmatch as well.

[Kenjister]

17 minutes ago, SyndicatedINC said:

It would appear that I wasn't clear enough in my question.  I am not asking why shells can bounce.  I am asking why do we have the specific arbitrary degrees of angle that make up autobounce instead of the actual ballistics of the shell versus the armor thickness at the angle of impact.   As both means of calculation would produce bounces still, why did WG create a new means of calculating it as they did? 

The penetration values of the shells assume normal impact angles.  However, in real life once the angles get high enough, the shell no longer penetrates in such a clean manner, and no longer follows the same penetration curve.  As Mouse showed in her quote, this is mainly because the shell doesn't "bite".  Think of it like a diver jumping into a pool.  At most angles they can cut through the surface smoothly, with all the power focused in a single point.  But there are certain angles which lead to a painful flop where a great deal of the force is spread out. 
If the game were to simply apply the same model to all impact angles, you would have an unrealistic model of penetration.  Instead, WG represents these high angle situations with a very simple autobounce/overmatch system, where any angles above 60 are automatically deflected unless the mass of the shell (roughly approximated by caliber) is enough to prevent deflection and punch through anyways.   

Does this lead to realistic penetrations?  Probably not, Mouse's source states it's usually around 70-80 degrees where penetration becomes near impossible by normal means.  But given the choice between 0 bouncing, and autobouncing at high angles, I'll take the autobouncing.  Its one of the few things in game keeping BB shells from ripping everything they touch to shreds with overwhelming penetration.

[SyndicatedINC]

5 minutes ago, Jinxed_Katajainen said:

Think it's just to keep everything simple and uniform.  Since the game doesn't take into account any details like armor quality or type and shell quality and type, it's just calculated as a slab of armor vs a shell coming in at x angle.

Honestly, it's much better as a game since there's no need to remember things like what an IJN Type 91 shell would do against a slab of Vickers Non cemented vs Wotan vs Class A, etc... just your AP shell will bounce if it hits at x degrees.  Also gives a point to work from when considering overmatch as well.

 

Good point, they would have been concerned with being overly complicated, which they didn't want.  They want you to be able to just play the game and shoot things, without knowing mechanics, and while that would be possible with the current autobounce mechanics as much as a more realistic one, the realistic one would probably feel "wrong" to many players due to the apparent inconsistencies of bounces depending upon shell and armor type/quality.  Makes sense that they wanted a more inuitive feel so likely made the arbitrary numbers as they were so results feel more consistent.  

[BrushWolf]

30 minutes ago, SyndicatedINC said:

It would appear that I wasn't clear enough in my question.  I am not asking why shells can bounce.  I am asking why do we have the specific arbitrary degrees of angle that make up autobounce instead of the actual ballistics of the shell versus the armor thickness at the angle of impact.   As both means of calculation would produce bounces still, why did WG create a new means of calculating it as they did? 

I would think because it is an arcade game that the simpler method was chosen to avoid excessive use of CPU cycles.

[KaptainKaybe]

If the shell is coming in at such a shallow angle that the pointy penetrative bit doesn't blow a hole into the armor first before the rest of the shell hits it, it can bounce off even (relatively) thin armor.

 

As to why they added the very specific /14.3 auto bounce calculation, regardless of shell weight and speed ... it's a game and it allows players to quickly do math to calculate their 'safety zones' when at less than 30 degree angle. This way, you don't have to worry about what exact ship, shell, and velocity you're facing ... just need to know the calibre.

 

Mind you, outside that auto bounce angle, every other hit takes all the above into account.

[More_Witches]

2 hours ago, RipNuN2 said:

This would be why . . . 

 

Reminds me of the War Thunder gif of an air dropped bomb bouncing cleanly off the rear of a T-34 turret

Edit: I found it

http://plays.tv/video/55d2257b98e5462df9/-warthunder

 

[VTAdmiral]

If it wasn't for autobounce, cruisers would have even less defense against battleships than they do now. It's pretty much the only thing keeping battleships from being stupidly overpowered, instead of just overpowered.

[TreeBurst82]

My memory is a bit hazy (please correct me) but this game DID have either nation specific shell normalization or nation specific autobounce angles - I cannot recall which one.  As it stands now USN autobounce angles are favorable compared to other nations so it might have been nation shell normalization.

I thoroughly enjoyed this mechanic - it gave more flavor and distinction to each nation's ships (simulating different manufacturing process, steel quality, etc etc).  It was removed to 'make the game less confusing'.  Sigh.

[AnatolyDyatlovDidNothing]

On 6/16/2017 at 2:58 PM, TreeBurst82 said:

My memory is a bit hazy (please correct me) but this game DID have either nation specific shell normalization or nation specific autobounce angles - I cannot recall which one.  As it stands now USN autobounce angles are favorable compared to other nations so it might have been nation shell normalization.

I thoroughly enjoyed this mechanic - it gave more flavor and distinction to each nation's ships (simulating different manufacturing process, steel quality, etc etc).  It was removed to 'make the game less confusing'.  Sigh.

 

I think there used to be nation specific autobounce angles. If i am remembering this correctly, i did not actually check.

 

It was all standardized a long time ago now, except for USN 203mm guns, which retains a more favorable angle of 45 degrees instead of 55 (i think). EDIT: Again, without checking i think it is done by gun caliber now. 406s have a certain number, 420s and 380/1s have others etc. It was just done to simplify things, which i was not against at the time and still am not. 

[byronicasian]

IIRC, from the EU forums, fnord_disc, the user who reverse engineered the in game pen formula mentions one of hte functions of autobounce is to prevent the formula from going out of bounds when extreme angles of impact cause division by zero. 

[comtedumas]

On ‎6‎/‎16‎/‎2017 at 11:52 AM, RipNuN2 said:

This would be why . . . 

 

if this is true, they the autobounce angles in this game are horribly off. 

[Helstrem]

36 minutes ago, comtedumas said:

if this is true, they the autobounce angles in this game are horribly off. 

The round in that GIF isn't bouncing off of armor.  It is bouncing off of a normal vehicle's skin.  There is nothing in that GIF that indicates the angle has to be that shallow in order for rounds to bounce off of armor.

[DanielLeary]

14 hours ago, grizzly95 said:

 

I think there used to be nation specific autobounce angles. If i am remembering this correctly, i did not actually check.

 

It was all standardized a long time ago now, except for USN 203mm guns, which retains a more favorable angle of 45 degrees instead of 55 (i think). EDIT: Again, without checking i think it is done by gun caliber now. 406s have a certain number, 420s and 380/1s have others etc. It was just done to simplify things, which i was not against at the time and still am not. 

For all ships (except USN CA's, RN CL's and the Hood) shells can start to ricochet at 45 deg with the frequency increasing until ricochets are guaranteed at 60 deg (provided that overmatch rules don't apply). For USN CA's and the Hood, shells can start to ricochet at 60 deg with the frequency increasing until ricochets are guaranteed at 67.5 deg. For RN CL's, shells can start to ricochet at 60 deg with the frequency increasing until ricochets are guaranteed at 75 deg. 

[comtedumas]

3 hours ago, Helstrem said:

The round in that GIF isn't bouncing off of armor.  It is bouncing off of a normal vehicle's skin.  There is nothing in that GIF that indicates the angle has to be that shallow in order for rounds to bounce off of armor.

It is a flawed comparison on that videos part.  basically you have a shell that is at approximately the same height as that car roof and it barely touches.  In game you have autobounce angles anywhere from 0 to 55 degrees or more....

Autobounce is a flawed game mechanic at best. 

[Special_Kay]

The reason is that ballistic penetration formulae start with the assumption that the shell is impacting nose-first. This ceases to be true at a sufficiently sharp angle (depending on the geometry of the shell in question). This is what LWM is saying.

In other words, effective thickness is irrelevant when the shell is bumped sideways away from the surface (unless the energy of the shell greatly exceeds the strength of the plate, e.g. a bullet through tinfoil, or a 2t shell through sheet metal; hence overmatch as an exception to autobounce).

 

So you may ask why, then, autobounce doesn't use the CRH of the shell? Why, then, doesn't overmatch use the kinetic energy of a shell? That's what is being answered when folks are saying "it's simpler for the server" or "it's easier for players to learn, this is an arcade game."

[BrushWolf]

13 minutes ago, Special_Kay said:

The reason is that ballistic penetration formulae start with the assumption that the shell is impacting nose-first. This ceases to be true at a sufficiently sharp angle (depending on the geometry of the shell in question). This is what LWM is saying.

In other words, effective thickness is irrelevant when the shell is bumped sideways away from the surface (unless the energy of the shell greatly exceeds the strength of the plate, e.g. a bullet through tinfoil, or a 2t shell through sheet metal; hence overmatch as an exception to autobounce).

 

So you may ask why, then, autobounce doesn't use the CRH of the shell? Why, then, doesn't overmatch use the kinetic energy of a shell? That's what is being answered when folks are saying "it's simpler for the server" or "it's easier for players to learn, this is an arcade game."

Even if this was a sim using autobounce would make sense to reduce calculations.