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DCS MG108 30mm and MG131 13mm projectile balistic drop


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I searched briefly forum and manual for values of ballistic drop over the travelled distance, but found nothing about it. Is here somewhere any research and table chart I missed?

 

Also are the MG 131 mounted in plane axis? Was Germans able to adjust its elevation angle?

 

Why I need this? Would be nice to know how much milirads I need to aim above to be able to hit target from longer ranges (200m-500m).


Edited by GumidekCZ
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http://109lair.hobbyvista.com/techref/manuals/manuals.htm

 

109G6U4 armament manual, last page has the wanted infos.

 

(assuming the gun installation and settings stayed the same for the K4 and also that DCS uses these values)

 

Thanks very much for some RW info.

But I'm still more interested in how it's modelled in DCS. Did someone compared RW data with ballistic trajectories we have in DCS now?

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But I'm still more interested in how it's modelled in DCS. Did someone compared RW data with ballistic trajectories we have in DCS now?

 

I've not done this for the MG131 or MK108, but I have done it for the MG151/20 on a different aircraft. You can use a similar technique to do your own measurements. This is what I did:

 

  1. Use the Mission Editor to build a test range
  2. Put the aircraft on a large open runway; you can save time by making it start with engines on.
  3. Place some tall objects at known distances and separations. The TV comms towers are good for this.
  4. These comms towers can be used to calibrate your gun-sight reticle angles
  5. Place some tall objects alongside the line between the aircraft and a point down range.
  6. Set the mission time to dusk (light enough to see the aircraft and towers, but dark enough to clearly see the tracers.
  7. Run the mission, fire some test shots and record a track. For the FW190, I needed to stand on the brakes and rev the engine up to give enough RPMs for the guns to fire. I am guessing the Bf109 will be the same.
  8. Replay the track in slow motion.
  9. Use an external view point (ideally, high zoom, long distance) to measure the trajectory. I did it by taking screen captures and them laying them on top of one another in the GIMP image editor.
  10. Use the known scale/placement of the comms towers (or whatever you used) to get the actual measurements.

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I've not done this for the MG131 or MK108, but I have done it for the MG151/20 on a different aircraft. You can use a similar technique to do your own measurements. This is what I did:

 

  1. Use the Mission Editor to build a test range
  2. Put the aircraft on a large open runway; you can save time by making it start with engines on.
  3. Place some tall objects at known distances and separations. The TV comms towers are good for this.
  4. These comms towers can be used to calibrate your gun-sight reticle angles
  5. Place some tall objects alongside the line between the aircraft and a point down range.
  6. Set the mission time to dusk (light enough to see the aircraft and towers, but dark enough to clearly see the tracers.
  7. Run the mission, fire some test shots and record a track. For the FW190, I needed to stand on the brakes and rev the engine up to give enough RPMs for the guns to fire. I am guessing the Bf109 will be the same.
  8. Replay the track in slow motion.
  9. Use an external view point (ideally, high zoom, long distance) to measure the trajectory. I did it by taking screen captures and them laying them on top of one another in the GIMP image editor.
  10. Use the known scale/placement of the comms towers (or whatever you used) to get the actual measurements.

I admit, I have difficulties to unzoom to long distance and decrease FOV angle still focus on towers, but still... I have some results. Unfortunately the picture shows something BUGy with Bf109 projectiles.

Tracers (both colors white & yellow) we see on picture belongs to only MG131 projectiles. 30mm MG108 dont have any tracers in DCS.

If shooting MG131 only , there are no bullet explosions. They emerge only when shooting MG131 and 108 together, on top of that the explosion are located on two areas. Question here is, if all bullet explosions belongs to same type of projectile on not.

xhGpFFt.png

2PcLhlP.png

2qNlpMl.png

 

 

According to this graph, its clear that MK108 falls more rapidly than MG131 rounds (lower muzzle velocity,...).But if you see the little explosions from last picture in my post above..there it opposite - expolsion near last TV tower with high explosions rate belongs to MG131 and the most left ones to MG108.

1nGCNPr.png


Edited by GumidekCZ
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I don't know if this is relevant here, but tracers in general have a slightly flatter trajectory than ball ammunition. The designers try to get the trajectory the same as the ball rounds they are meant to be used with, but it's not always possible.

The tracer has more favourable ballistic qualities thanks to aerodynamic effects - while the composition is burning it reduces drag on the projectile.

 

If that is what is happening here, I am impressed...

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  • 2 weeks later...

I thought, that this toppic would create more discusion and interest, but apperently not.

So I would like to move this toppic by admins into BUG report, because I think, that:

Bullet explosions not following tracers.

Missing 30mm round tracers.

Ballistic drop of both weapons not following trajectories as drawn at attached diagram above.

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Here is my test mission, download it and try it for your self.

What a pitty, that Fw190D cant shoot at ground.

 

[ATTACH]242936[/ATTACH]

 

You can, if you rev the engine a bit.

 

Also, according to the graph, the 30mm should cross the visor at 400m, but they don't seem to do that in your example.

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...

Tracers (both colors white & yellow) we see on picture belongs to only MG131 projectiles. 30mm MG108 dont have any tracers in DCS.

 

That is not correct. With Combat Mix, High Explosive and Training Ammo the MK108 have tracer.

 

If shooting MG131 only , there are no bullet explosions. They emerge only when shooting MG131 and 108 together, on top of that the explosion are located on two areas. Question here is, if all bullet explosions belongs to same type of projectile on not.

...

 

You should put MG131 and MK108 on separate buttons and not on first detent MG and second detent MG together with MK

 

2PcLhlP.png

2qNlpMl.png

 

 

According to this graph, its clear that MK108 falls more rapidly than MG131 rounds (lower muzzle velocity,...).But if you see the little explosions from last picture in my post above..there it opposite - expolsion near last TV tower with high explosions rate belongs to MG131 and the most left ones to MG108.

 

The MG131 bullets have no explosions. Only the MK108 rounds have. The two different explosion clouds are from the MK108. The closer one is from the non-tracer rounds, the further ones are from the tracer rounds. Shoot only MK108 rounds and you will see that. Use unlimited ammo.

 

1nGCNPr.png

 

The trajectory of MG131 and MK108 cut the "line of sight" at 400m, with a bullet drop of 390cm(MG) and 340cm(MK). I would expect the MK bullets to be below MG bullets from 400m onwards. It is hard to draw a correct line of sight on a screenshot.

The line of sight of the Revi is not parallel to the MK and MG barrel(s).

 

 

I don't know if this is relevant here, but tracers in general have a slightly flatter trajectory than ball ammunition. The designers try to get the trajectory the same as the ball rounds they are meant to be used with, but it's not always possible.

The tracer has more favourable ballistic qualities thanks to aerodynamic effects - while the composition is burning it reduces drag on the projectile.

 

If that is what is happening here, I am impressed...

 

Looks like it is that way in DCS.

 

 

Comments in red

 

 

Fox

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