Information on projectile velocity over distance

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1
Would you like to see this in-game?
  • Yes, as is
  • Yes, but differently (explanation in replies would be appreciated)
  • No, I wouldn’t
  • Other (explanation in replies would be appreciated)
0 voters

Hello!

Currently, when looking at the stat card of a projectile (for example, 90 mm M82), the only velocity value stated is the muzzle velocity. I’ve created this suggestion to give ideas on how, in the future, the game could provide ways to see the velocity of the projectile over distance.

90 mm M82 statcard

90 mm M82 statcard

Why should this be added?

There are a couple reasons why I can think that knowing the velocity of your projectile at longer distances would be helpful.

The first is simply that it gives you a better idea of how well your projectile behaves over distance, and the performance you can expect. Typically this can be seen with how much penetration your projectile loses over range, but this would add additional information.

The second, and main reason why I’m doing this, is bug reports.
As of right now it is impossible to bug report the velocity loss over distance of any round that isn’t a conventional armor-piercing round, including semi-armor-piercing rounds. This means basically any APCR, SAP, APDS, APFSDS, HE, HESH or HEAT round could have velocities that don’t match the real life values at all, and it’s simply not possible to actually make a bug report on it.

And even with conventional AP rounds (that is: AP, APHE, APC, APBC, APHEBC and APCBC), bug reporting this is a chore. The only way to do it is to “reverse” the AP round calculator that is on the WarThunder wiki, plugging in velocity values until you reach the penetration that is stated in game, and comparing to real life documentation. You might notice that the wiki does show a calculator for APCR, but this calculator does not match the game (this is something I’ve tried to bring the attention of the developpers to).

How could this be added?

From the get go, I have two ideas on how this could be done.

  1. The first, and possibly simplest, is to just add a line on the stat card of every single projectile, which states the velocity at, for example, 1000 meters. Here, I’ve editted the previous M82 statcard to show how this could potentially look.
Editted 90 mm M82 statcard

Editted 90 mm M82 statcard
You can see, after the “Muzzle velocity” stat, there is an additional “1000 m Velocity” stat, which states 774 m/s (I’ve taken this value out of “Terminal Ballistics Data V3”).

  1. Add velocity information to protection analysis. For example, an extra line below the “Armor penetration” value which states the projectile velocity at the range that has been selected. I’ve eddited the protection analysis interface to show how it could potentially look.
Editted Protection Analysis interface

Editted Protection Analysis interface

That is all for my suggestion. Please do give more suggestions on how you would add this to the game if possible.

2 Likes
2

Maybe just add it to sensors view?

3

Sensors view?

4

A couple of things.

it would be easier to show speed loss per 100m in the stat card.
So in the 90mm M82 case the stat card would say:
Speed loss per 100m: 7.9 m/s

it would be easier to convert to relevant distances for testing.

This value would change with firing angle in relation to flat ground. if you fire downwards from a hill the slowdown would be less because gravity is accelerating the round whilst if you fire from low to high the gravity would decelerate the round making it slowdown more.
I don’t know if this is something war thunder includes in its calculations though.

this addition would be suited for the sensor view in replays more than anywhere else.

5

Well, copy of tacview, maybe that explains better

6

That’s not how ballistics work. The slower the shell gets, the less velocity it loses.

And?

Ever seen a ballistic table for ammunition? No one cares what the velocity at 1000m is when you you shoot straight into the air.

The entire point of the system is explained by OP:

1 Like
7

Except speed loss isn’t constant. 😕

M82 is a projectile that has very good drag (in general the 90 mm projectiles do), so the difference with distance doesn’t change much. But with smaller cannons firing lighter rounds, the deceleration becomes noticeably smaller with distance (as the projectile slows down, drag decreases exponentially). And even more the case when you factor in APCR rounds.

For example, 90 mm M304 APCR has a muzzle velocity of 3350 ft/s (1021 m/s), and at 1100 yards (almost exactly 1000 meters) the velocity is 2868 ft/s (874 m/s), leading to a velocity difference per 100 meters of 14.6 m/s. But if you were to use directly the 100 yard velocity, which is 3305 ft/s (1007 m/s), you’d get a velocity loss of 15 m/s every 100 meters. You can’t really do precise math with it.

And M304 has very good drag for an APCR round.

Also, for these values I used another source called “ARMOR-PIERCING AMMUNITION FOR GUN, 90-mm, M3”. It seems to follow the exact same curves as thoses provided in TBDV3, except it states the exact ft/s numbers rather than a graph where there is incertainty in measurement.

Yes. However it is how projectile stat cards, and most importantly all sources are written.

I could see the sensor view showing something of the sort, stating the velocity of the projectile at a specific moment in time. But unless you add another specific extra line that states the distance the projectile has traveled, this wouldn’t add much. Beyond that, it wouldn’t work with the idealistic scenarios that both stat cards and real life sources use.

1 Like
8

Kinda pointless. Why would you need the ballistic data in a replay?
The data should simply be visible in the stat card.

But I guess there could also be some debug menu that enables players to see more information, that isn’t necessary for the average player, since this suggestion is mostly bug report related.

So here’s my alterantive implementation: Give us a debug menu that player can enable for additional information, like ballistics, fire chance and stuff like that.

At the moment the system of bug reporting performance of shells is hardly possible, since Gaijin doesn’t accept datamine as proof and the game simply doesn’t provide that information.

9

Debug menu might be very good for any weapon reports. Currently in game a lot of “hidden” values for missiles, like a booster force and time

1 Like
10

There’s also APCR and APDS round cores, which is information that is inside the game but completely inaccessible except with datamines (which are ignored in bug reports).

However I remember there already being a suggestion for that. Maybe it was just in the old forum though.

1 Like
11

Why not both in the Protection analasys as well as on the stat card a 4th Line after 60° penetration to have each Velocity at 0m, 100m, 500m, 1000m, 1500m and 2000m

12

That could probably work. I just don’t want to overbloat the stat card hence why I suggested only a single extra line of information.

13

in the context of the confines of the game; its close enough for this to not practically matter.
But in general you are correct yes.
At slower speeds its linear, but at higher it quadratic. the speed at which this (approximately) changes is highly dependant on individual rounds (Reynolds number).

but really, the difference in deceleration from 100m to 200m and 2000m to 2100m might differ like 0.5m/s or there around. (IIRC, it was a while ago i looked into this)
not at all enough for it to matter in any meaningful way in the game.

Part of the intentions stated was to give a clearer picture of how the round behaves over distance.
The Abrams have MP rounds intended partially for helicopters so firing that round at a tank 2km away downhill or a helicopter 4km away at 5km height makes quite the difference.

for example:
Firing down hill at lets say 30 degrees (for ease of math) at a target 2km laser distance away.
Using right angle trig you get a birds eye distance of about 1730m.
That 1730m is the distance you set the elevation at for correction.

that would be a 300m difference in aimpoint in your crosshair which with slower rounds can mean a hit or a miss.
(Here is a great video explaining it)

Granted my example is a bit extreme to show what i mean, but the difference can still be enough for it to matter quite a bit with the slower rounds in the game.