WTs aircraft ammunition damage mechanic compared to reality

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 penetrating shells (1)


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.

Incendiary performance of penetrating shells (2)


In WT Incendiary and armor piercing incendiary rounds have a set chance to cause a fire.
This means that an API can set a fuel tank on fire under any circumstance as long as it hits it.

In reality shells often release their incendiary effect on impact while other shells only do that when they strike armor plates. In both cases the round might not cause a fire because the incendiary burned up before it reaches anything flammable or the incendiary was simply never released.

Generally are two types of Incendiary shells:

API or Incendiary rounds with an Incendiary mixture in the nose or below a fuze that is ignited on impact and shells that need to hit an armor plate to break up.




Berezin 12.7mm API and API-T with flashpowder in the nose, activated on impact.

Berezin 12.7mm API with phosphorus behind steel core, activated by breaking up on armor plates.

The former has the big advantage of direct hits having a great chance to ignite fuel while the latter might simply make a hole in the tank any only causing fires under the specific scenario of encountering armored fuel tanks.

Impact activated incendiary rounds also depend on their velocity. The faster the round travels the more distance the burning incendiary mixture is carried. This means that at long range, the incendiary efficency generally decreases since the round “loses” it’s incendiary properties before it reaches the fuel.

Of course the quanity of the incendiary mixture carried, also plays a role.

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.

Penetration performance of AP ammunition


In reality there is generally a big difference between an AP rounds penetration against against bare armor, where the round hits the plate directly, and its performance when it first impacts on another surface, some distance before the armor plate.

The reason for this is that the shells gets destabilized and starts to tumble, striking the armor plate while the nose of the projectile is pointed in another direction of the flight path.

So the penetration mechanic switches from perforating the plate to smashing through it with just kinetic energy. This generally reduces the armor penetration to below caliber level.

Most planes features armor plate thickness between 6-12mm, which generally provides protection against rifle calibers and heavy machingun calibers under the condition that the armor plate isn’t struck directly by the bullet.

A usual rifle calibe AP bullet penetration drops from 10-12mm at 100m to just around 4mm or less when it first impacts the planes structure.
US and Soviet 12.7mm bullets will penetrate just 8-11mm under these conditions.

Jacketed bullets are generally more affected by this but center of gravity seems to play the biggest role. AP rounds that have their center of gravity at the front will keep their nose pointed forward, while rounds with their center of gravity further back will start to spin or tumble.

An Hipano training round, practically an inert explosive shell, with a steel nose cap for a fuze will be able to penetrate around 15mm of armor, both direct or when striking the planes structure, because the front heavy shell doesn’t get destabilized.

Likewise, the Hispano AP and AP-T rounds featured a plastic nose cap and the cavity that could contain a tracer caused the shell to be front heavy and keep its penetration in any way.

However because the Training round could essentially achive the same results as the AP round, the AP was later on replaced by the 20mm SAPI by simply putting a solid nose plug on the 20mm HEFI and filling it with incendiary mixture.
Creating a round that could penetrate practically any armor found on fighter planes while also setting fire to engines and protected oil and fuel tanks.

The ShVAKs 20mm API round with steel core on the other hand was inferior in armor penetration to even the 12.7mm.

However a side effect from tumbling is potentially greater damage, since a round passing through a spar or fuel tank sideways will cause more damage then making a caliber sized hole into it.

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.


I think I’m mostly done with this topic.

Feel free to remind me of some other thinks to talk about.

Maybe I’ll add another section for different types of explosives.