Findings and Questions regarding Bomb damage in v4.005

[=KG76=flyus747]

FINDINGS:

The recent patch made changes not just to aircraft ammunition but also bombs. Some of the changes caught me by surprise. Without source material for every single bomb, I assumed IL2 always had accurate information regarding the effects of bombs, but this new patch introduced huge changes to how bombs work making me question not just which (v4.004 or v4.005) is more accurate. 

 

For those wondering how bombs have changed since v4.004 to v4.005, this is what I have found.

 

The following findings were found in the game files:

• LW and USSR's equivalent bombs use exact same files for explosions. i.e SC250 = FAB250. It is a 1:1 copy inside. Only difference is the 3D model of the bomb.

SC50 radius increased from 40 to 56.0

Shrapnel quantity increased from 770 to 6452

 

SC250 (FAB250) radius increased from 56 to 75.4

Shrapnel Quanitity increased from 4800 to16432

 

SC500 (FAB500) radius dropped from 100 to 91.6

Shrpanel quantity increased from 10400 to 22952

 

SC1000 radius dropped from 160 to 120.2

Shrapnel quantity increased from 18800 to 23732

 

SC1800 radius dropped from 200 to 119.6

Shrapnel quantity increased from 32400 to 36391

 

SC2500 radius dropped from 200 to 133.9

Shrapnel quantity increased from 19080 to 22780

 

It is surprising to see such dramatic changes in the blast radius of some bombs such as the SC2500 and huge increases in shrapnel quantity across the board. There are many more variables mentioned in each of these files, but many of which I don't understand which leads us to the next part.

 

 

QUESTIONS:

1. How does IL2 calculate bomb damage? Is it a combination of layers and a shrapnel spraying in multiple directions like a real bomb explosion would have? I assume first of all, there are a few layers, each with a set radius and damage output. Then, I think there is the shrapnel. If I understand correctly, v4.005 introduced shrapnels to explosions meaning if you are really unlucky, you could be hit far away by a stray piece of shrapnel, however, I have no proof this actually exists, just pure speculation. Looking at v4.004's files, a "ShrapnelQuantity" also exists.

2. Attached below is the raw "explosive" data of a German SC2500 in v4.005 and v4.004 (scroll down). There are a few lines I can't seem to make sense of:

   Spoiler

   v4.005's SC2500 

   Class_name = "CBatchExplosion"
   object_name = "HE_810mm_2400kg_1923kg_ground"

   // БЧ снаряда/бомбы, расчитнано из ТНТ=1923кг, массы снаряда 2400кг, калибра 820мм

   //////    PhysicsBody properties
   VisualImage=0,"graphics\effects\Arm\hit_shell_he_620-970kg_ground.epl",false
   VisualRadius=200
   ImageAttr=17        //IA_NOCLIP | IA_NOMINPIXELS

   SoundScript="LuaScripts\Sound\explosions\Bomb\Ground_Large.cfg"

   GroundImage="graphics\Grounds\crater_150.mgm"

   ExplosionPower=1.0            // Сила звука взрыа, переменная для FMOD
   Animation=1                    // Номер хука взрыва
   LiveTime=20                // Время жизни взрыва
   AnimationTime=20            // Время анимации взрыва
   Ranges=1,0.01,0.99,0        // (кол-во вариантов, начало 1го диапазона, конец 1-го диапазона, дельта прибавляемая к границам для следующего диапазона)
   //"RangesCnt, Range0Start, fRange0End, fRangeStep"; ARG=m_fRange0Start+(m_fRange0End-m_fRange0Start)*t+m_fRangeStep*data->m_RangeIdx
   //Ranges=1,0.01,0.99,0
   //Ranges=2,0.01,0.49,0.5
   //Ranges=3,0.01,0.32,0.33
   //Ranges=4,0.01,0.24,0.25
   //Ranges=5,0.01,0.19,0.2

   // Параметры Sphere Hit, внешний взрыв

   Radius=133.9    // Радиус сферы воздействия взрыва, определяющий выборку объектов
   TNT_equ=1923    // Тротилловый эквивалент для моделирования атмосферной ударной волны

   // Фугасное воздействие: дальность, (-1 не использ.), пары (броня, дамаг за броней)
   ArmorFoug=0.0,-1,    1676,837945,    0,1675889
   ArmorFoug=9.4,-1,    5,2265,            0,4531
   ArmorFoug=44.8,-1,                    0,198
   ArmorFoug=89.1,-1,                    0,50

   // Осколочное воздействие
   ShrapnelQuantity=22780
   FragmentMass=0.0084
   // Единичный осколок: дальность, скорость, пары (броня, дамаг за броней)
   ArmorShr=0.0,1418,    855,842,    684,2105,    0,3368
   ArmorShr=12.9,1162,    426,566,    341,1414,    0,2263
   ArmorShr=66.8,467,    18,91,        14,229,        0,366
   ArmorShr=133.9,190,                1,15,        0,60

    

    

    

    

   v4.004's SC2500 

   Class_name = "CBatchExplosion"
   object_name = "tnt1900kg_frag500kg_expl_ground"

   // БЧ снаряда/бомбы, расчитнано из ТНТ=1923кг, массы снаряда 2400кг, калибра 820мм

   //////    PhysicsBody properties
   VisualImage=0,"graphics\effects\Arm\hit_shell_he_620-970kg_ground.epl",false
   VisualRadius=200
   ImageAttr=17        //IA_NOCLIP | IA_NOMINPIXELS

   SoundScript="LuaScripts\Sound\explosions\Bomb\Ground_Large.cfg"

   GroundImage="graphics\Grounds\crater_150.mgm"

   ExplosionPower=1.0            // Сила звука взрыа, переменная для FMOD
   Animation=1                    // Номер хука взрыва
   LiveTime=20                // Время жизни взрыва
   AnimationTime=20            // Время анимации взрыва
   Ranges=1,0.01,0.99,0        // (кол-во вариантов, начало 1го диапазона, конец 1-го диапазона, дельта прибавляемая к границам для следующего диапазона)
   //"RangesCnt, Range0Start, fRange0End, fRangeStep"; ARG=m_fRange0Start+(m_fRange0End-m_fRange0Start)*t+m_fRangeStep*data->m_RangeIdx
   //Ranges=1,0.01,0.99,0
   //Ranges=2,0.01,0.49,0.5
   //Ranges=3,0.01,0.32,0.33
   //Ranges=4,0.01,0.24,0.25
   //Ranges=5,0.01,0.19,0.2

   Radius=200                    // Радиус сферы воздействия осколочно-фугасного воздействия
   TNT_equ=1923                // Тротилловый эквивалент

   // Фугасное воздействие
   ArmorFoug1=1,-1,    8012,4006250,    0,8012500
   ArmorFoug2=2,-1,    1282,641000,    0,1282000
   ArmorFoug3=10,-1,    80,40063,        0,80125
   ArmorFoug4=40,-1,    12,6410,        0,12820
   ArmorFoug5=200,-1,    1,256,            0,513

   // Осколочное воздействие
   ShrapnelQuantity=19080
   // И для каждого осколка просуммируется
   ArmorShr1=1.0,-1,    454,320,    0,1280
   ArmorShr2=62.5,-1,    408,288,    0,1152
   ArmorShr3=124.1,-1,    363,256,    0,1024

   I have no coding experience so I don't know if any of this is some basic basic coding info. Some of the lines I can make out their meaning but because most of the explanatory texts are in Russian (I used Google Translate to English), I can't exactly understand what it is it's trying to explain.

 

//Ranges - what do these lines mean?

Radius - Blast radius in Meters

TNT - Amount of TNT in Kilograms

ArmorFoug - ???

 

ShrapnelQuantity - Amount of Shrapnel produced by explosion

FragmentMass - Mass of each shrapnel framgent.

 

ArmorShr - ???

Edited May 3, 2020 by =KG76=flyus747
Made mention that game files used as source to determine radius and shrapnel quantity

[41Sqn_Skipper]

In many programming languages a "//" is used to begin a comment within the source code. This means the rest of the line is ignored and the purpose of the text behind the "//" is only for human readers of the source and usually provide further explanations for better understanding.

 

Or it is sometimes used to "disable" lines of old code that is no longer needed. (Bad coding style, better delete the line and trust your revision control system)

 

 

Edited April 30, 2020 by 41Sqn_Banks

[DeadMeat0383]

I am not sure the information you have there is correct on the 1800 and 2500kg bombs... in a recent flyout on the unprofessionals we found that the 1000kg bomb was actually doing more damage to soft targets (eg, we were blowing up a town) than the 1800 and 2500 bombs.

 

I will be making a mission tomorrow when I have time to do some further testing

[Velxra]

Hmm yes the blast radius of the SC1800 and SC2500 seems odd given how these are fairly bigger in size to the next step down in bombs. I would expect this to be at least 50 meters or more in additional radius due to the additional explosive.  

 

[DeadMeat0383]

Sorry, to clarify, we found the explosion radius in practice for the 1000kg was larger than the 1800 and 2500

[=KG76=flyus747]

On 4/30/2020 at 11:45 PM, DeadMeat0383 said:

Sorry, to clarify, we found the explosion radius in practice for the 1000kg was larger than the 1800 and 2500

The numbers provided were extracted from v4.005d (most recent version) of the game. I don't know if practicing in game is an accurate source.

 

Variations in testing may have been possible due to inconsistent testing factors thus making the SC1000 seem more destructive than the 1800 or 2500.

On 4/29/2020 at 5:13 AM, 41Sqn_Banks said:

In many programming languages a "//" is used to begin a comment within the source code. This means the rest of the line is ignored and the purpose of the text behind the "//" is only for human readers of the source and usually provide further explanations for better understanding.

 

Or it is sometimes used to "disable" lines of old code that is no longer needed. (Bad coding style, better delete the line and trust your revision control system)

 

 

Yes, I think you are right. I looked at older versions of the game (v3.012) and these lines remain "//" out. Maybe its dead lines from the RoF times? Who knows.

On 4/30/2020 at 11:36 PM, Geronimo553 said:

Hmm yes the blast radius of the SC1800 and SC2500 seems odd given how these are fairly bigger in size to the next step down in bombs. I would expect this to be at least 50 meters or more in additional radius due to the additional explosive.  

 

Yeah it's weird how those two are nearly identical in terms of blast radius. I have heard the amount of TNT packed in these two bombs were really not that far apart. The huge weight difference was to allow the bombs to penetrate hard bunkers and stuff of similar builds (I am not certain of this though). Still, the 2500 should be bigger right?

Edited May 3, 2020 by =KG76=flyus747