Weight of ammunition, particularly US .50 caliber.

[FeuerFliegen]

I was trying to figure out exactly what each round weights, so I did the math on what you state as the weight for a specific amount of additional rounds for planes such as P38, P40, P47.

 

In the P-40, .50 cal rounds  weigh approximately 0.137kg per round

 

In the P-38 and P-51, .50 cal rounds weigh approximately 0.124kg per round

 

In the P-47 and Spitfire XIV, .50 cal rounds weigh approximately 0.141kg

 

I know these aren't huge differences, but I'm just wondering why the discrepancy?  Are there belts, links, etc. that affect this?  This ammo weight would mean that a P-47 with max ammo would weigh about 58kg more than if it used the weight figures from a P-51 or P-38.

 

[czech693]

Interesting find.  I wouldn't think there would be any difference in weight unless it was because of different type of rounds, which we can't change.

[Stonehouse]

Could be wrong but I believe they all use a common bullet definition and weapon definition.  Then the mount definition in the particular aircraft has a specific definition for that weapon for that aircraft. This covers things like the gun position in the aircraft, position for the case ejection, how the mount affects dispersion, barrel temperature cooling rate etc. So the Spitfire XIV uses the MG_USA_M2-50.txt definition which uses the bullet_usa_12-7x99_ap.txt projectile definition. Mass in there is 0.04588 kg or 45.88 gms. 

 

 

 

 

[354thFG_Rails]

On 6/25/2023 at 7:25 AM, SCG_FeuerFliegen said:

I was trying to figure out exactly what each round weights, so I did the math on what you state as the weight for a specific amount of additional rounds for planes such as P38, P40, P47.

 

In the P-40, .50 cal rounds  weigh approximately 0.137kg per round

 

In the P-38 and P-51, .50 cal rounds weigh approximately 0.124kg per round

 

In the P-47 and Spitfire XIV, .50 cal rounds weigh approximately 0.141kg

 

I know these aren't huge differences, but I'm just wondering why the discrepancy?  Are there belts, links, etc. that affect this?  This ammo weight would mean that a P-47 with max ammo would weigh about 58kg more than if it used the weight figures from a P-51 or P-38.

 

Where did you find this?

[FeuerFliegen]

2 hours ago, 86th_Rails said:

Where did you find this?

 

Going to plane modifications that offer additional ammo, it gives a weight figure for that ammo.

[354thFG_Rails]

Very strange. Good find. 

[LukeFF]

I'll send this one up the chain and see what they say.

[LukeFF]

Alright, the word from up above:

 

Quote

Most likely the numbers come from historic data, probably the difference includes weight of ammo boxes and racks, chain links, and things like this.

 

Also, it is requested that solid historical data be provided to see whether there is actually a problem. ?

[FeuerFliegen]

On 6/28/2023 at 1:12 PM, LukeFF said:

Alright, the word from up above:

 

 

Also, it is requested that solid historical data be provided to see whether there is actually a problem. ?

 

Thanks, I suspected it may have been something to do with links, racks, boxes, etc.

 

That being said - I always thought that once you fired off all of your rounds, you would lose that stated weight.  But if that includes other things like boxes, racks, etc., then is not all of that weight expended along with the ammo?

 

One related question too, which in my opinion, shows a clear discrepancy unless there is something that differentiates these two modifications-

 

Fw 190 A-5 MG FF/M 20mm additional wing-mounted gun with 90 rounds per gun.

Ammunition mass: 37 kg

Guns mass: 94 kg

Estimated speed loss: 6 km/h

 

Fw 190 A-3 MG FF/M 20mm additional wing-mounted gun with 90 rounds per gun.

Ammunition mass: 50 kg

Guns mass: 94 kg

Estimated speed loss: 8 km/h

 

Why the different ammo mass?  I thought these mods were identical.  Also, speed too?

[LukeFF]

18 minutes ago, SCG_FeuerFliegen said:

Thanks, I suspected it may have been something to do with links, racks, boxes, etc.

 

That being said - I always thought that once you fired off all of your rounds, you would lose that stated weight.  But if that includes other things like boxes, racks, etc., then is not all of that weight expended along with the ammo?

 

One related question too, which in my opinion, shows a clear discrepancy unless there is something that differentiates these two modifications-

 

Fw 190 A-5 MG FF/M 20mm additional wing-mounted gun with 90 rounds per gun.

Ammunition mass: 37 kg

Guns mass: 94 kg

Estimated speed loss: 6 km/h

 

Fw 190 A-3 MG FF/M 20mm additional wing-mounted gun with 90 rounds per gun.

Ammunition mass: 50 kg

Guns mass: 94 kg

Estimated speed loss: 8 km/h

 

Why the different ammo mass?  I thought these mods were identical.  Also, speed too?

 

Okay, I'll ask about this one.

[Regingrave-]

2 часа назад, SCG_FeuerFliegen сказал:

Why the different ammo mass?  I thought these mods were identical.  Also, speed too?

Maybe they are identical, maybe not, nost probably that comes from difference in documents. But you should understand that you're haggling over 0.3% of the standart plane mass, the effect of this difference on speed would be non-existent.

[=MERCS=JenkemJunkie]

You can also use the unGTP extractor to see the ammo weights when full and empty by looking in:

IL-2 Sturmovik Battle of Stalingrad\data\(null)\luascripts\worldobjects\planes

Once its extracted, open the file for the plane you want and scroll down until you find a section that looks like this:

 

 

 

 

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In here it shows that the P38 keeps some of the ammo weight, but the P47 doesn't. If you add the green 5.042 kg and blue 37.257 kg in the P38 picture and divide it by the red 300 rounds you get ~0.141 kg, same as if you divide 37.649 kg by 267 rounds from the P47 picture. But in the P51D 49.676 kg divided by 400 rounds is ~0.124 kg, and other planes have different values too (Spit 9/14, P39 is ~0.141, and P40, P51B is ~0.136), so there is a difference between planes, and I don't know why. The P38 has a Russian note next to it that says "overweight compared to the mass of the BC P-51" so at least some of the differences are intentional for whatever reason.

 

Both the A3 and A5 have 37 kg as the ammo weight for the 90 rounds of MG FF in the game files, it's only different in the spec page.