(17-6-2018) Mk108 30 mm cannon - incorrect muzzle velocity

[Ein79 5,743]

DxDiag - attached: DxDiag-bug-mk108.txt

Server replay - link: https://warthunder.com/en/tournament/replay/336886042014753867
Client Log - attached: mk108-bug-report-2018_06_15_20_16_29__6140.clog

 

 

 

Weapon type: Rheinmetall-Borsig Mk108 30 mm cannon

--> https://wiki.warthunder.com/index.php?title=Mk108

 

 

The issue: Incorrect muzzle velocity

 

In game the muzzle velocity is lower than according to the official manual (link below): 

 

D. (Luft) T. 6108, MK 108 3cm Flugzeugmaschinenkanone 108, Waffen-Handbuch, Stand Oktober 1943, Teil 1. 

 

The value given by mentioned Waffen-Handbuch is 525 m/s, when in game we have now 500 m/s (was 510 m/s pre-1.79 Update).

 

 

The purpose and justification of the revision:  

 

The Mk108's performance has a direct impact on 17 vehicles in the game (list below the report) including paid premium vehicles and events rewards.

Please don't lower their effectiveness when it's not necessary!  

 

I'm aware that some sources state value 500 m/s. Same as you are aware that there are some publications that give even up to 540 m/s for Mk 108's muzzle velocity. 

But if we have equivalent historical sources, I see no reason to favor those sources that rated the velocity of the Mk 108 cannon to the lowest possible level. 

 

Mk 108 cannon is already extremely hard to aim, especially at distances greater than 100 m. And now we have the lowest possible settings.  

With such a low muzzle velocities every meter per second counts, making the aiming a bit easier or more difficult.
As a person who play a lot Me262s, I can even feel the differens between 510 m/s (pre-1.79) and current 500 m/s (post-1.79). And the same feel other persons I asked in recently played matches.
Proposed  +25 m/s difference is gonna make a decent impact on trajectory, drop and bullets flight time. 

Most, if not all, opponents of German aircrafts armed with Mk108 cannon have HMG or cannons with much higher muzzle velocity and much greater effective range.

This is particularly painful in jets battles and let me remind you that Me262C and Me163B are facing such fast and maneuverable aircrafts as Mig17, Hunter and Sabre.

So from the point of view of the game balance, there is no reason to make using the Mk108 cannon even more difficult and less effective at distance. 

We should rather make it as good as the legitimate sources allow, and such a source is the Waffen-Handbuch just mentioned, which states 525 m/s for Mk-108 muzzle velocity:

D. (Luft) T. 6108, MK 108 3cm Flugzeugmaschinenkanone 108, Waffen-Handbuch, Stand Oktober 1943, Teil 1. 

Additional source:  Entwurf von Rheinmetall-Borsig 09.06.1943

 

Affected Vehicles:

 

Bf 109 G-6
Bf 109 G-10
Bf 109 G-14
Bf 109 G-14 /AS (Italian)
Bf 109 K-4
Bf 109 Z-1 (premium)
Bf 110 G-2
Fw 190 D-12
He 162 A-1  (event reward)
He 219 A-7 (premium)
Me 163 B
Me 262 A-1a
Me 262 A-2a (event reward)
Me 262 C-1a
Me 262 C-2B
Ta 152 H-1
Ta 154 A-1 (premium)

 

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mk108-bug-report-2018_06_15_20_16_29__6140.clog

DxDiag-bug-mk108.txt

 

 

 

Edited June 19, 2018 by Einherjer1979

[LordMustang 7,395]

Hey @Einherjer1979,

 

Thanks for your report. I will investigate this issue.

 

[HerrSektor 3,836]

Hi, the 30mm Mk103 and Mk108 used different rounds from the same type...

 

by example:

• There where rounds with 85grams of PETN, and where blunt nosed bullets... Called as 30x91mm Mk108 Ausf. A...
• Later, the germans made these bullets more aerodinamic and a bit ligther, but the PETN load was reduced to 72grams of PETN... this one was called as Ausf. C...

 

for the muzzle speeds, if i can remember well... and im can be wrong about here...

• 30mm Minengeschoß Ausf A (blunt-nosed with 85 grams of PETN): 510 m/s
• 30mm Minengeschoß Ausf C (streamlined nose with 72 grams of PETN): 540 m/s
• 30mm Brand-granate (Incendiary round with 140g incendiary composite): 490 m/s

 

[LordMustang 7,395]

The 'Munitionsvorschrift for Fliegerbordwaffen Teil 10' mentions a V₀ of 500m/s for all ammunition types for the Mk 108. Sources seem a little conflicting on this one. Are there any more sources that confirm 525m/s?

[LordMustang 7,395]

Alright, I've found another source, one of the last messages send by Borsig, claimining 520m/s. Given that both this message and the Handbuch are probably more reliable than the Munitionsvorschrift, I'll pass this on.

[LordMustang 7,395]

The bug report has been submitted.

This thread will remain unlocked for 7 days in order to allow anyone with information/examples or additional sources to post them.


It will also serve as a place where the developers may post questions, so please keep up to date here.

Thanks for your time and effort

[Ein79 5,743]

On 17/06/2018 at 14:21, LordMustang said:

[...] Are there any more sources that confirm 525m/s?

Additional source:  Entwurf von Rheinmetall-Borsig 09.06.1943

 

http://www.germanluftwaffe.com/archiv/Dokumente/ABC/m/MK 108/Text/Entwurf Borsig 09.06.1943/Entwurf von Borsig.pdf

[LordMustang 7,395]

On 19/06/2018 at 20:16, Einherjer1979 said:

Additional source:  Entwurf von Rheinmetall-Borsig 09.06.1943

 

http://www.germanluftwaffe.com/archiv/Dokumente/ABC/m/MK 108/Text/Entwurf Borsig 09.06.1943/Entwurf von Borsig.pdf

Added, cheers.