20mm option on 109K-4?

[Kurfurst]

54 minutes ago, E69_geramos109 said:

@VO101Kurfurst What do you know about the ammo indicator for the Mk108 on the K4? Do they install that ammo counter as standar?

 

In the 109K Flight Handbook, Part 9A there is a picture of the cocpit instruments, but there is only two ammo counters - I suppose that ammo counters were for the MG 131 only on the 109K.

[Yogiflight]

2 hours ago, VO101Kurfurst said:

 

In the 109K Flight Handbook, Part 9A there is a picture of the cocpit instruments, but there is only two ammo counters - I suppose that ammo counters were for the MG 131 only on the 109K.

Would have made more sense to use the first ammo counter for the MK 108 and the second one for one of the MG 131s, as the second MG 131 most likely will have the same amount of ammo as the first one.

[sevenless]

1 hour ago, Yogiflight said:

Would have made more sense to use the first ammo counter for the MK 108 and the second one for one of the MG 131s, as the second MG 131 most likely will have the same amount of ammo as the first one.

 

Well unlikely that in the K4 it was any different than in the G6/U4. MG131 and MG151 on Button A and MK 108 on Button B.

 

 

 

 

Edited June 15, 2020 by sevenless

[Yogiflight]

@sevenless is the text from the manual, you posted above it? Because the manual says MK 108 wing gondolas, while the text is about MG 151/20 wing gondolas and MK 108 engine cannon.

It makes sense to shoot the 151/20 gondola guns together with the 131 machine guns, as their trajectory is much closer than the one of the 108.

But what you quoted was about the ammo counter in the K4, which in my opinion would have made more sense to make the one counter for the 108 and the other one for the 131s, as you don't need to see if the left machine gun has as much ammo left as the right one, so one counter for both machine guns would have been enough.

But it seems german engineers/pilots/Luftwaffe leaders were different opinion.

[sevenless]

1 hour ago, Yogiflight said:

@sevenless is the text from the manual, you posted above it? Because the manual says MK 108 wing gondolas, while the text is about MG 151/20 wing gondolas and MK 108 engine cannon.

It makes sense to shoot the 151/20 gondola guns together with the 131 machine guns, as their trajectory is much closer than the one of the 108.

But what you quoted was about the ammo counter in the K4, which in my opinion would have made more sense to make the one counter for the 108 and the other one for the 131s, as you don't need to see if the left machine gun has as much ammo left as the right one, so one counter for both machine guns would have been enough.

But it seems german engineers/pilots/Luftwaffe leaders were different opinion.

 

Hi Yogi,

 

you find the complete manual here: http://109lair.hobbyvista.com/techref/manuals/bf109g6u4.pdf

 

The quotes I posted from that refer to the central Mk108 of the G6/U4.

 

If you are interested in the manual for the gondola Mk 108s (I think it is Rüstsatz 6 mod) which also were tested but AFAIK never saw service in the field, please have a look here: https://www.deutscheluftwaffe.com/archiv/Dokumente/ABC/m/Messerschmitt/Me 109/Bf 109 G-6 U4 Wa Beiheft 1 MK 108.pdf

 

That one, about the gondolas, also has a picture about the ammo counters. See page 17 and about the ballistic trajectories.

 

 

 

Quote

so one counter for both machine guns would have been enough.

 

Yes and that was how it was done if the G6 was carrying gondolas (my guess). One counter MG131, one counter Mk108 and one counter wing (2xMk108 or 2xMG 151) if I understand the manual correctly.

 

The interesting part about the 2xMk108 manual is this on page 6:

 

 

So in case the 109 is flying with 5 guns (3xMk108), then Button A is triggering (2x131 and 1x108) and Button B is triggering the gondola Mk108s.

 

That means it is only a question of telling your weapons guy how you want to have your weapons grouped and wired. Could be done in the field easily.

 

 

Edited June 15, 2020 by sevenless

[Raven109]

I thought the gondolas only had one light to the left and one to the right of the cockpit, indicated by annotation a. on the dashboard image, and no counters.

 

Annotation c. denotes the MG131 counters, as you can see by the lines going from c. to the two side ammo counters.

 

Funny enough, the center counter has no caption.

Edited June 15, 2020 by Raven109

[sevenless]

6 minutes ago, Raven109 said:

Funny enough, the center counter has no caption.

 

Yes but it is described in the text. See 3. Elt Anlage:

 

 

If flying with 3 guns, then it is left (131), middle (108) and right (131).

[Raven109]

25 minutes ago, sevenless said:

 

Yes but it is described in the text. See 3. Elt Anlage:

 

 

If flying with 3 guns, then it is left (131), middle (108) and right (131).

 

Thanks, I was nit-picking about the missing caption.

 

Right, but that is the normal layout. I mean you don't get one MG131 counter assigned to the gondola cannons (or any other cannon, as Yogi would like the K4 to be). 

 

It's probably like this because the two MG131 counters were always assigned to the same button and could never be split between two buttons.

 

Although, looking at the manual, they were individual units, so you could use one counter for the 2xMG131 and one for the MK108.

 

https://www.deutscheluftwaffe.com/archiv/Dokumente/ABC/s/SZKK/LuftT6505Schusszeahler.pdf

Edited June 15, 2020 by Raven109

[sevenless]

18 minutes ago, Raven109 said:

Right, but that is the normal layout. I mean you don't get one MG131 assigned to the gondola cannons (or any other cannon, as Yogi would like the K4 to be). 

 

Good question. To me the layout seems flexible enough that this could be done by the weapons guys in the field, but that is, I have to emphasize that, my personal impression. You don´t find that written expressis verbis in the manual.

But think about it... in case of 5 gun setting (20mm gondolas) the wiring has to be changed so that trigger button A is (2x131 and 2x151) and button B is (1x108) and in case of 5 gun setting (30mm gondolas) the wiring has to be changed so that button A is (2x131 and 1x108) and button B is (2x108). That tells me that it can´t be that complicated to do for the random field armorer.

Edited June 15, 2020 by sevenless

[Raven109]

30 minutes ago, sevenless said:

 

Good question. To me the layout seems flexible enough that this could be done by the weapons guys in the field, but that is, I have to emphasize that, my personal impression. You don´t find that written in the manual.

But think about it... in case of 5 gun setting (20mm gondolas) the wiring has to be changed so that button A is (2x131 and 2x151) and button B is (1x108) and in case of 5 gun setting (30mm gondolas) the wiring has to be changed so that button A is (2x131 and 1x108) and button B is (2x108). That tells me that it can´t be that complicated to do for the random field armourer.

 

I think you already had the wiring in place, inside the wing. So when you connected the gondolas, you only connected them to either the wire going to the A button, or to the wire going to the B button, if they were 151 gondolas, or 108 gondolas, respectively. Interesting enough is that the 108 motor cannon is on the same button as the MGs? Even though they had different ballistics.

 

I don't think you ever get to know (in any combination) the amount of ammo inside the gondola cannons. The only cockpit feedback about the gondolas was a control light for each one (indicating a working/jammed gun) on the left/right side of the instrument panel, but never a counter. This could be for ease of maintenance.

 

Not sure why after 4 years of war during which they used 3 ammo counters to represent the ammo in the 109 with its default setting, they went to only two counters. It might be one more late 109 model awkwardness because of the manufacturing process.

 

 

Edited June 15, 2020 by Raven109

[sevenless]

54 minutes ago, Raven109 said:

 

I think the button to cannon wiring was already in place, for all combinations.

 

Yes that is what I meant, not laying new wires, maybe my non native english failed me here. The wires are all in place, they only need to change the contacts on the distribution box.

 

Quote

I don't think you ever get to know (in any combination) the ammo inside the gondola cannons.

 

By the same system as for the three center guns? Manually set the counter to the amount of ammo (1) and then electricity is doing the rest (2), I guess.

 

(1)

(2)

 

Quote

It might be one more late 109 model awkwardness because of the manufacturing process.

 

I don´t think so. See the corresponding plate for Fw190 Dora-9 SZKK 4 below. I guess we are far from knowing all the details because certain documents are either lost or things were so "normal" that they thought it to be self explanatory for the audience back then. What I mean is the fact that in the picture of the K4 manual are only 2 counters, it does not necessarily mean that in the planes back then there were also only 2 counters.

 

 

And then we have the SZKK 4 for the Fw 190 A7/8 R2 here, which does not show the MG 131 at all except for the controllights:

 

Edited June 15, 2020 by sevenless

[JG5_Schuck]

Im just curious, in the image above, the MG131's counters are at a different hight?

Does this indicate a fault, as surely the guns where synced together?

Or as stated where they used for each set of guns....

[Raven109]

35 minutes ago, JG5_Schuck said:

Im just curious, in the image above, the MG131's counters are at a different hight?

Does this indicate a fault, as surely the guns where synced together?

Or as stated where they used for each set of guns....

 

There is a knob on each counter, which can be used to control how high the "white line" goes. When the plane was rearmed, the ammo guy turned that knob to set it at the desired height which meant a certain number of shots (there is a scale along the white line, and a number at the top which indicates how many rounds does having a full white line mean).

 

The "white line" was actually a diagonal painted on a vertical cylinder, which separated it into a white and black half. Each time the gun was fired the cylinder would rotate.

 

It could be that in the image they were set to different heights, because it's really easy to do, just to show a difference between the counters.

 

Got the image below from another forum (1 is the cylinder, 2 is the knob).

 

 

----------------------------

53 minutes ago, sevenless said:

 

Yes that is what I meant, not laying new wires, maybe my non native english failed me here. The wires are all in place, they only need to change them on the distribution box.

 

 

By the same system as for the three center guns? Manually set the counter to the amount of ammo (1) and then electricity is doing the rest (2), I guess.

 

(1)

(2)

 

In this case you'd have to use the middle counter for both gondolas and the engine cannon (since they usually have the same ammo type). But I think the issue with this is that the control light/spinner at the top is connected at the same input as the ammo counter. I don't think they can be separated, which would mean that it will indicate a fault for all three guns if just one goes, if that's even possible. Just assuming.

 

The manuals always show a fixed arrangement (i.e: gondolas without a counter; bottom right Motor 151 without ammo, which seems to imply that only the motor cannon was mapped to the middle counter, even when you had gondolas):

 

 

Edited June 15, 2020 by Raven109

[sevenless]

23 minutes ago, Raven109 said:

In this case you'd have to use the middle counter for both gondolas and the engine cannon (since they usually have the same ammo type). But I think the issue with this is that the control light/spinner at the top is connected at the same input as the ammo counter. I don't think they can be separated, which would mean that it will indicate a fault for all three guns if just one goes, if that's even possible. Just assuming.

 

Well for the trigger buttons it was suggested (2x131 and 1x108) on trigger A and (2x 108) trigger B, so I see no reason why the counters couldn´t be grouped 2x131, 2x108 and 1x108. However all funny speculation. I integrated the SZKK 4 for D9 (4 guns) and A8/R2 (6 guns) above in my post just to show the general flexibility of the system.

Edited June 15, 2020 by sevenless

[Raven109]

3 minutes ago, sevenless said:

 

Well for the trigger buttons it was suggested (2x131 and 1x108) on trigger A and (2x 108) trigger B, so I see no reason why the counters couldn´t be grouped 2x131, 2x108 and 1x108. However all funny speculation. I integrated the SZKK 4 for D9 (4 guns) and A8/R2 (6 guns) above in my post just to show the general flexibility of the system.

 

It also seems modular to me, but it might be that you could only have one counter per gun, since each spinner/light indicated the status of one gun. Since there are more lights/spinners than counters (in the 109), it seems to imply that it was more important to the pilot to know the status of the gun (working/jammed) rather than the ammo count.

 

But I agree, we don't have enough information about how the real birds were setup, just by looking at the manuals.

[sevenless]

43 minutes ago, Raven109 said:

The manuals always show a fixed arrangement (i.e: gondolas without a counter; bottom right Motor 151 without ammo, which seems to imply that only the motor cannon was mapped to the middle counter, even when you had gondolas):

 

 

 

Thanks for that. Yes that looks convincing for me.

 

3 minutes ago, Raven109 said:

it seems to imply that it was more important to the pilot to know the status of the gun (working/jammed) rather than the ammo count.

 

Yep, agree on that. The pilot sooner or later will have a "feeling" how much trigger time is left. Jamming is the more important information.

Edited June 15, 2020 by sevenless

[sevenless]

Just FYI,

 

a good online documentation about the Geraetebrett (instrument panel) and the ZSKK2 and ZSKK3 you find here:

 

Looks like K4s used both ZSKK2 and ZSKK3, dependant on availability and delivery shortages during production.

 

https://www.deutscheluftwaffe.de/nachbau-geraetebrett-me-109-k-4

https://www.deutscheluftwaffe.de/nachbau-geraetebrett-me-109-g6-r3

 

ZSKK2:

https://www.deutscheluftwaffe.de/fl-47317-schalt-zaehl-kontrollkasten-szkk-2-1944

 

 

ZSKK3:

https://www.deutscheluftwaffe.de/fl-47318-schalt-zaehl-kontrollkasten-szkk-3-1944

[Raven109]

Good find. This seems to confirm that you could add or remove modules for counters as needed, and is inline to what we assumed before. This can be seen in the attached pic of the K4 dashboard, where the middle module is missing:

 

 

I think also, @Yogiflight's suggestion about the ZSKK2 would work (where only 2 counters are available). If we assume that you can only use one counter per gun:

a. The 1st counter would be used for the MG131s, showing the amount of ammo for just one gun (this should be enough, because the ammo goes down at the same rate for both guns, and you could just do a 2x in your head to find out the total number of shots left)

b. The 2nd counter would show the number of shots left for the MK108. 

 

The only small caveat is that the counter for the cannon would have to have a greater resolution for its scale (i.e be a 100 counter, rather than a 500, as we have for the MG131s).

 

 

[Yogiflight]

50 minutes ago, Raven109 said:

The only small caveat is that the counter for the cannon would have to have a greater resolution for its scale (i.e be a 100 counter, rather than a 500, as we have for the MG131s).

That is what I had thought about, too. Maybe they were just short of 100 round counters for what reason ever (maybe higher priority for 500 rounds counter)

[LukeFF]

There is original footage of a K-4 in April 1945 that shows it had only 2 ammo counters installed:

 

https://www.youtube.com/watch?v=9_V7mY2ubVw

[Raven109]

2 minutes ago, LukeFF said:

There is original footage of a K-4 in April 1945 that shows it had only 2 ammo counters installed:

 

https://www.youtube.com/watch?v=9_V7mY2ubVw

 

Yes the 2nd one is a K4 and seems to be equipped with the ammo counter which could support 3 counters, ZSKK3, but has only two slots filled in, just like the crop I posted above. As the others have said, perhaps resource availability made it so that each aircraft was equipped according to what they had at the end.

[sevenless]

1 hour ago, Raven109 said:

 

Yes the 2nd one is a K4 and seems to be equipped with the ammo counter which could support 3 counters, ZSKK3, but has only two slots filled in, just like the crop I posted above. As the others have said, perhaps resource availability made it so that each aircraft was equipped according to what they had at the end.

 

Here is the relevant caption of the K4 "weisse 8" from april 1945 from the site below.

 

 

https://www.deutscheluftwaffe.de/cockpitprofil-messerschmitt-bf-109-k-4

 

You can translate the site with google. It talks a lot about material shortages and reduction of materials. The relevant quote is this:

 

Quote

"Diesen Original-Dokumenten kann man in Bezug auf tatsächliche Ausrüstungsstände immer nur bedingt trauen. Wie die Ausgabedaten bereits verraten, wurden dise Unterlagen bereits vor dem Serienanlauf im Oktober 1944 erstellt. Vieles hat sich erst nach Serienanlauf ergeben, was in diese Dokumente nicht mehr eingearbeitet wurde. Allerdings erhalten bereits diese Dokumente Hinweise auf Teile, die später entfallen werden, was bei der Serie auch umgesetzt wurde."

 

The video on youtube shows that it either has already been looted for souvenirs (look the ripped off plate on the pilot seat, loose wires etc.) or was build in a catastrophic state in the last days of the war. I suspect the former is the case.

 

 

And last but not least we still have this remark in the G6/U4 manual (06/1944), which says that the counter for the MK108 was not functional, because one distribution box was missing:

 

 

Translation by google: "The shot counter for the MK108 is not yet connected because the switch rail on the MK 108 is not yet installed."

 

What if they never ever managed to make that MK108 counter work at all and because of that silly MK 108 switch rail (distibution box?) stopped integrating it in the ZSKK3 at a certain point in time? We possibly will never know.

Edited June 16, 2020 by sevenless

[Kurfurst]

Whatever the case is with individual planes, the video of the downed 109K certainly shows that the current cocpit model is not wrong per se, and at the very least it corresponds to (some? all?) historical examples.