WTs aircraft ammunition damage mechanic compared to reality (in-progress)

I wanted to create a suggestion about reworking how aircraft (+ground) shells work in damaging components.

However I realized that explaining what is wrong with the current system would take up way too much space and is a topic on its own.

Pilot/Crew as Module + Damage based on penetration


Everything in WT is a module. The engine, fuel tanks, structure etc.
What makes Pilot/Crew different from these objects is that they are in fact alive and don’t react well to getting shot. In-game every object has a hidden HP bar that when damaged changes color to indicate the amount of damage the component received.
The damage inflicted is based on various factors but one important one for kinetic rounds is armor penetration. This can make sense for a lot of solid modules, as the more penetraiton a round has the more damage is infliced to sturdy modules like engines.
However, there’s a limit where penetration makes any sense to determine the damage inflicted.

  • In-game a 20mm Ball or Tracer shell with 10-12mm penetration, fails to take out a Pilot because the damage is determined by the penetration of the shell. An AP round with +20mm penetration will usually take out a Pilot.
  • Likewise the damage inflicted to a fuel tank is also higher when a same caliber round has more penetration. Again this makes no sense.

→ Penetration power is necessary to damage certain components. However a lot of aircraft modules don’t require a lot of penetration. After a certain penetration threshold is reached, the damage inflicted shouldn’t be based on the penetration anymore. For a Pilot or Fuel tank it makes no difference, if a 20mm shell with 500m/s penetrates them with 5, 10 or 20mm of potential armor penetration.

Spoiler (12.7mm dealing more damage than 20mm Practice to Pilot)

Missing Kinetic component of explosive shells


Explosive round damage is entirely determined by the weight of the shell + the amount of explosive.
However WT doesn’t take the kinetic component of the shell into account.

Now just consider the following:
A 20mm M97 HEI has around 8g TNT equivalent of explosive filler.


The shell weighs around 130g with maybe 80g of steel body directly affected by the explosive, while fracturing the rest of the shell (fuze, bottom).
The initial velocity of fragments reaches 600m/s according to some report on the shells fragmentation.
This results in the explosion creating fragments without around 15KJ of energy at most, while the shell itself has a muzzle energy of 45KJ. At 300m the shell still carries around 32KJ in kinetic energy.

Compared to a Soviet 20mm HEFI, which has around 18.5KJ of energy at 300m, a Hispano-like HEFI shell carries more kinetic energy than the fragments released from just the explosion, meaning if the the Hispano-like 20mm shell only carries enough explosive to fragment the shell without increasing their velocity, it still delivers more kinetic energy with than the lighter Soviet 20mm shell with fragments from its blast.

It’s clear why 23mm cannons replaced the 20mm shells, in Soviet service. At 300m the Kinetic component is around equal to the 20mm Hispano while delivering twice or more the explosives.
Delivering more destruction at the cost of ballistics.

Something similiar can be seen with Japanese 30mm cannons. The Armies Ho-5 20mm cannon did not deliver enough explosive or KE into the target for the weight of the gun and in order for Japanese fighter to carry more firepower a light 30mm cannon was suppose solve this issue.
This 30mm cannon fired relatively light shells (~270g) with approximately 16-24g of explosive filler, depending on the shell type.
The shells also had a lower muzzle velocity in addition of having worse ballistics due to having a large aerodyamic profile compared to the weight of the shell, meaing that at 300m the kinetic energy of a 30mm HE projectile was actually roughly the same as a 20mm Hispano HEI.
So the gun is able to deliver more explosive for the price of having worse ballistics, similiar to the 23mm NR-23, made worse by the fact that the RoF is around 50% slower than the 20mm cannon.



Carrying more energy means that the fragments are able to pierce more material and cover a greater distance. It also increases the incendiary chance, since the burning incendiary composition is more likely to reach flamable material before it burns out.

Incendiary performance of shells


Incendiary effect in WT seems to be based entirely around RNG, which each round having a specific fire chance. This is most notable in 12.7mm rounds with high rate of fires and incendiary chances exceeding that of a lot of 20mm cannnons even.
The “onHitChanceMultFire” stat for some common calibers from datamining:

  • 7mm Inc → 4.0
  • 7mm API → 5.0
  • 12.7mm Inc → 8.0
  • 12.7mm API or API-T → 10.0
  • 15mm Inc-T → 8.0
  • 15mm API → 7.0
  • 20mm Inc → 8.0
  • 20mm API → 10.0

Not only do 12.7mm have equal or higher chance to set fuel on fire than some larger rounds, API rounds in general are straigt up superior in terms of incendiary chance compared to incendiary rounds that often lack any armor penetration.
While the incendiary chance is dependant on the design and other factors of the round, in general it should be clear that a larger round would have better incendiary properties.

I’ve experienced multiple times from videos and playing that self-sealing fuel tanks can go from unharmed to being turned light yellow and be set on fire from rounds being fired at 600m and further, in a split second.
However incediary chance to fuel tanks should depent on more than just RNG:

  • In reality Incendiary chance against fuel tanks is increased the faster the shell travels, meaning incendiary rounds will lose efficency over distance.
  • Direct hits, meaning the less distance the shell has to travel to reach the fuel tank, would result in much higher likelyhood of setting the fuel tank on fire
  • Fires can be internal or external. Damaged and leaking fuel tanks would be easier to set on fire even from small incendiary rounds.
  • Some Incendiary rounds, like most German API or British 20mm SAPI, carry incendiary inside the shell, which is only released when the shell impacts on an object with increased resistance like a thin armor plate. Either by breaking appart or through a detonator. Which it the same time means that these shells would be specifically effective against fuel tanks protected by armor plates while otherwise not having incendiary properties.

Explosive power is overrated, Incendiary underrated


We’ve seen before that the explosives added to a shell doesn’t increase the KE of the fragments by a huge margin. A faster, heavier shell can make up for it by delivinger more KE by itself.
If we compare the 20mm High Explosive Incendiary rounds to a pure Incendiary rounds, we’ll see that they are very similiar in construction.
The Incendiary round almost acts as SAP, penetrating the aircrafts structure while releasing burning incendiary compound. In contrast the HEI shell explodes on impact, fracturing the shell and damaging components in a wide area. The incenediary effect of the HEI shell is limited to close proximity of the impact, while the Incediary round can hit components on the other side of the airframe.

Early explosive shells were usually filled with just explosive compound but they were pretty much always substituted with shells that either had a high incendiary content or used an explosive mixed with zinc or aluminum to enhance the incendiary properties of the explosion itself.

The destructive power of the explosive was just not worth the added benefits of causing a fire to fuel or oil inside the plane. Bringing down a plane with kinetic damage through fragments as well as the incendiary chance was more likely than with the blast of the explosive.

This makes Mineshells actually the only types of shells that can really rely on their explosive power. Only they carry enough explosives to regularly bring down an aircraft by causing structural damage, which was of course their designed purpose.
While they were designed around the principle that the structure of an aircraft is the biggest target and therefore the most likely to hit, they also come with a problem:
The larger the target, the more structural damage is needed to bring it down.

There’s a reason why Germany developed and used 30mm Incendiary rounds, when they previously only used Mineshells for the MK 108. The later developed 30mm Mine-Incendiary shell would basically cut down the explosive in half for delivering an incenediary payload.
By loading 100% of Mine-Incendiary rounds instead of 50:50 Mineshell and Incendiary, each hit is much more lethal to a fighter than an Incendiary on average while the chance of setting a large bomber on fire with each shot increases.

After all, while a bomber has a large structure, it also carries very large fuel tanks that are easier to destroy than to bring down the bomber with enough structural damage.

I will continue this topic at another time, since I can’t create any other topics in the mean time for some reason.

I also summon @Conraire to maybe get some more insight on shell performance and incendiary chance.

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