MW 50 tank weight (Bf 109)

Shortways · Oct 20, 2025

Shortways said:
I'll check out that manual. Thanks

Edwin

In the meant time ... One question came to mind (hopefully related enough because of MW-50) ... about the DB 605 AM engine. It's performance graphs no longer show the 1,42 ata curve as it is replaced by the 1,70 ata. However this G-14 performance sheet still shows the 1,42 ata setting in the small list of data.
The MW-50 System first had to be armed by the flip-switch on the control panel and was subsequently activated when the throttle passed the detent and triggered the activating switch. The engine went to 1,70 ata in this situation.
Question:
Were in the throttle range, did the engine reach 1,42 ata? I suppose it still had the the time limit, so I guess you would want it 'passed the detent'? The (before the) detent being 1,30 ata. And so, was there some room/range passed the detent until hitting the MW-50 activation switch.

if you want I can delete this and open up a new post?

Edwin

Engineman · Oct 20, 2025

Shortways said:
In the meant time ... One question came to mind (hopefully related enough because of MW-50) ... about the DB 605 AM engine. It's performance graphs no longer show the 1,42 ata curve as it is replaced by the 1,70 ata. However this G-14 performance sheet still shows the 1,42 ata setting in the small list of data.
The MW-50 System first had to be armed by the flip-switch on the control panel and was subsequently activated when the throttle passed the detent and triggered the activating switch. The engine went to 1,70 ata in this situation.
Question:
Were in the throttle range, did the engine reach 1,42 ata? I suppose it still had the the time limit, so I guess you would want it 'passed the detent'? The (before the) detent being 1,30 ata. And so, was there some room/range passed the detent until hitting the MW-50 activation switch.

if you want I can delete this and open up a new post?

EdwinView attachment 852552

Hi Edwin,
Congratulations on deducing the complications of the engine control system of the DB605, especially the late versions with different fuels and MW 50!
The first thing to say is that all Bf 109 simulations I have seen, fail to operate the engine and instrumentation exactly in the way that it did for real!
Take the basic DB605A without MW, the throttle at 100% in Automatik gives 2600/1.30. If you want the full 110%, you move the throttle through the gate
and move it further forward. As the throttle moves forward you incrementally get increasing rpm and ata until, at max travel of throttle, you get 2800/1.42,
so there is a range over about 4cm where the rpm/ata increases, not just a simple jump.
The same happens with MW 50. The MW 50 cuts in at throttle positions above the 100% gate and rpm/ata rise with further throttle movement until you get to
2800/1.70 at 110% (throttle lever at the max travel). As you can tell, this means you pass through a position that gives 1.42ata, but the rpm will not be 2800 at 1.42, except
at about 6.5km altitude where the max MAP (Manifold Air Pressure) has dropped to 1.42ata anyway, giving 2800/1.42 at that point, not above (ata will drop further) or below
(ata will increase).
The reason for this type of behaviour is because of the way the engine controls function. The rpm control is not effected by the adjustments for MW 50, but the
MAP control is changed and given a different 110% setting.
Does that make sense to you?

Cheers

Eng

Shortways · Oct 20, 2025

Engineman said:
Hi Edwin,
Congratulations on deducing the complications of the engine control system of the DB605, especially the late versions with different fuels and MW 50!
The first thing to say is that all Bf 109 simulations I have seen, fail to operate the engine and instrumentation exactly in the way that it did for real!
Take the basic DB605A without MW, the throttle at 100% in Automatik gives 2600/1.30. If you want the full 110%, you move the throttle through the gate
and move it further forward. As the throttle moves forward you incrementally get increasing rpm and ata until, at max travel of throttle, you get 2800/1.42,
so there is a range over about 4cm where the rpm/ata increases, not just a simple jump.
The same happens with MW 50. The MW 50 cuts in at throttle positions above the 100% gate and rpm/ata rise with further throttle movement until you get to
2800/1.70 at 110% (throttle lever at the max travel). As you can tell, this means you pass through a position that gives 1.42ata, but the rpm will not be 2800 at 1.42, except
at about 6.5km altitude where the max MAP (Manifold Air Pressure) has dropped to 1.42ata anyway, giving 2800/1.42 at that point, not above (ata will drop further) or below
(ata will increase).
The reason for this type of behaviour is because of the way the engine controls function. The rpm control is not effected by the adjustments for MW 50, but the
MAP control is changed and given a different 110% setting.
Does that make sense to you?

Cheers

Eng

Hi Eng,

That actually makes perfect sense.

But why does the 'km / PS / u/min / ata'– table show 2800 rpm at 1,42 ata at sea level?

Engineman · Oct 20, 2025

Shortways said:
Hi Eng,

That actually makes perfect sense.
But why does the 'km / PS / u/min / ata'– table show 2800 rpm at 1,42 ata at sea level?

Hi,

This is because the whole development of the DB 605 was in a state of flux during the WW2, and particularly in 1943 to 1945. The new changes saw old engine performance
standards and specifications rewritten and redefined.
The engine could in fact operate at 2800/1.42 in Hand control, but this was not approved as it was difficult to control.
There are contradictions like this in the late engines manuals.

Eng

Shortways · Oct 20, 2025

Engineman said:
Hi Edwin,
Congratulations on deducing the complications of the engine control system of the DB605, especially the late versions with different fuels and MW 50!
The first thing to say is that all Bf 109 simulations I have seen, fail to operate the engine and instrumentation exactly in the way that it did for real!
Take the basic DB605A without MW, the throttle at 100% in Automatik gives 2600/1.30. If you want the full 110%, you move the throttle through the gate
and move it further forward. As the throttle moves forward you incrementally get increasing rpm and ata until, at max travel of throttle, you get 2800/1.42,
so there is a range over about 4cm where the rpm/ata increases, not just a simple jump.
The same happens with MW 50. The MW 50 cuts in at throttle positions above the 100% gate and rpm/ata rise with further throttle movement until you get to
2800/1.70 at 110% (throttle lever at the max travel). As you can tell, this means you pass through a position that gives 1.42ata, but the rpm will not be 2800 at 1.42, except
at about 6.5km altitude where the max MAP (Manifold Air Pressure) has dropped to 1.42ata anyway, giving 2800/1.42 at that point, not above (ata will drop further) or below
(ata will increase).
The reason for this type of behaviour is because of the way the engine controls function. The rpm control is not effected by the adjustments for MW 50, but the
MAP control is changed and given a different 110% setting.
Does that make sense to you?

Cheers

Eng

Hi Eng,

That actually makes perfect sense.

But why does the 'km / PS / u/min / ata'– table show 2800 rpm at 1,42 ata at sea level

Engineman said:
Hi,

This is because the whole development of the DB 605 was in a state of flux during the WW2, and particularly in 1943 to 1945. The new changes saw old engine performance
standards and specifications rewritten and redefined.
The engine could in fact operate at 2800/1.42 in Hand control, but this was not approved as it was difficult to control.
There are contradictions like this in the late engines manuals.

Eng

Ah … roger. I guess, when you're being bombed, even 'Deutsche Grundlichkeit' goes down the drain. Thanks a lot for the excellent insights. Luckily the simulation developers are inclined to go along with technical details like this. We'll get it as realistic as possible within the technical possibilities.

O … by the way, I might have found another hint of the weight of the 115ltr tank including plumbing. There is a document that is a collection of the official technical specification documents for all types of DB 605… the DB 605 A has a 'Einbaugewicht des Triebwerks (mit Zusatzgeräte) of 764kg, while the AM's is 794kg! So 30kg! I know … It's circumstantial evidence, but hey … rumours rumours
The picture in the attachment shows parts of those specifications at the bottom. The top part is a comparison between G-6 and G-14, where I brought the armour of the G-6 on par with the G-14'd, added the lighter 20kg tank and 70ltr/63kg of MW-50. This resulted in the exact same weight for the then G-6/U3 vs the G-14.

Engineman · Oct 20, 2025

Hi,

That is good deduction from the data sheets.

Eng

Jaivan · Oct 20, 2025

Some weights of MW 50 systems to compare,

1) From Beladevorschrift zum Ladeplan Nr. 109 K 401 (Bf 109 K-4), dated 27.9.44:

2) From Beladevorschrift zum Ladeplan Nr. 109 K 461 (Bf 109 K-4/R-6), dated 8.2.45:

3) O'gau handwritten calculations for Bf 109 G-6/R-2:

Tanks for G-14 and K-4 were made by Firma Raspe-Werke, (Geräte Nr. 8-4365 B, C u. D), while the 70 l for recce machines was made by Firma BNE, Gerät Nr. 9-2351 B-1.

Engineman · Oct 20, 2025

Good details.
Item 3) "O'gau", is probably reference to the Messerschmitt design dept dispersed location at Oberammergau.

Eng

Shortways · Oct 21, 2025

Well ... and history throws another curveball! The 115 ltr Behälter is back! … In the K4.
But those systems are really very light. The G-6/R2 only 11 kg. Tanks of 6-7 kg.

Thank you Jaivan

Shortways · Oct 22, 2025

There it is, the K-4 115 ltr tank.

Shortways · Oct 22, 2025

In these two examples, you can see the difference between the modified GM-1 tank and the 'dedicated' MW-50 tank. The modified tank did not have a pressurization line coming from the manifold and thus had the bottles in the wing.

Shortways · Nov 8, 2025

Shortways said:
I'll check out that manual. Thanks

Edwin

Found what you referred to in the Bf 109 Kompendium of course ...

Apart from that, I have been researching the story behind the G-6's with MW-50 installations, because I want to categorize/name the simulated version. I initially inclined towards the U3, but I found a number different discussions and published material that have shifted my opinion towards the U2, of which apparently about 300 were converted from GM-1 to MW-50 (late 1944) I will explain in the following text that I wrote for myself:

THE FOLLOWING IS MY PERSONAL INTERPRETATION BASED ON A NUMBER OF DISCUSSIONS ON DIFFERENT FORUMS, AS WELL AS PUBLICATIONS, COMBINED:

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

THE G-6/U3 WAS A LOW ALTITUDE RECONNAISSANCE AIRCRAFT (NAHAUFKLÄRER)

It was a modification of either a standard G-6 or a G-6/U2 with GM-1 installation.

THE G-8 WAS THE PRODUCTION VERSION OF THE G-6/U3.

There is some confusion about the U3 being either a Fighter or a Recce aircraft; Looking at the G-8, the answer to this, seems to be that it was both!

The G-8 not only has cameras (2 Rb 12,5/7x9 — 12,4 kg or 2 Rb 32/7x9 = 17,6 kg and a 2,4x2,4 Robot II Kleinbildkammer), it also has the standard 2x MG-131 and 1x MG-151/20 gun-configuration ... and on top of that, it could carry the underwing MG-151/20 Gondelwaffen and ... a 300 ltr External Tank ... or 1x 250 kg Bomb or 4x 50 kg bombs.

The U3 most likely had the same configuration.
Records of a number of 'Nahaufklärungsgruppen (NAG)' or Low Altitude Reconnaissance Wings/Squadrons, show a number of G-6/U3's in their ranks together with G-8's

The G-8 which was newly factory-built and did not have GM-1 nor MW-50; The G-8 Handbuch states :
'Teil 0 – Allgemeine Angaben / 7C – GM 1-Anlage - entfällt'

However, the G-6/U3's were modifications of existing G-6's, some of which were GM-1 equipped U2's.

GM-1 had some operational difficulties and as the DB 605 AS with improved (DB 603-) Supercharger came into service, it became obsolete. The AS engine's performance proved sufficient, so aircraft with the GM-1 installations (tanks) were logical candidates for modification to MW-50 as this involved minor adaptation.
Later, a lighter 'dedicated' MW-50 system also became available as this was standardly built into the G-14's.
This system was also retrofitted into some G-6/R2(3) High Altitude Recce aircraft that did not already have any 'Zusatzeinspritsung' (GM-1 or MW-50), but it is unlikely that it was incorporated into the U3, as they did not see the need to equip the G-8 with MW-50 either.
The fact that they did build it into some G-6's, was because these, by chance/availability, were G-6-U2's anyway and it may have been easier to convert the GM-1 system, than to remove it.

This does mean that the G-6/U3's and a number of converted U2's, were (only) equipped with the 20-30 kg , heavy, converted, 115 or 85 ltr GM-1 tanks, that used pressurized air bottles, placed in their right hand wing, to pressurize the MW-50 Tank.

Engineman · Nov 8, 2025

Shortways said:
Found what you referred to in the Bf 109 Kompendium of course ...

Apart from that, I have been researching the story behind the G-6's with MW-50 installations, because I want to categorize/name the simulated version. I initially inclined towards the U3, but I found a number different discussions and published material that have shifted my opinion towards the U2, of which apparently about 300 were converted from GM-1 to MW-50 (late 1944) I will explain in the following text that I wrote for myself:

THE FOLLOWING IS MY PERSONAL INTERPRETATION BASED ON A NUMBER OF DISCUSSIONS ON DIFFERENT FORUMS, AS WELL AS PUBLICATIONS, COMBINED:

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

THE G-6/U3 WAS A LOW ALTITUDE RECONNAISSANCE AIRCRAFT (NAHAUFKLÄRER)

It was a modification of either a standard G-6 or a G-6/U2 with GM-1 installation.

THE G-8 WAS THE PRODUCTION VERSION OF THE G-6/U3.

There is some confusion about the U3 being either a Fighter or a Recce aircraft; Looking at the G-8, the answer to this, seems to be that it was both!

The G-8 not only has cameras (2 Rb 12,5/7x9 — 12,4 kg or 2 Rb 32/7x9 = 17,6 kg and a 2,4x2,4 Robot II Kleinbildkammer), it also has the standard 2x MG-131 and 1x MG-151/20 gun-configuration ... and on top of that, it could carry the underwing MG-151/20 Gondelwaffen and ... a 300 ltr External Tank ... or 1x 250 kg Bomb or 4x 50 kg bombs.

The U3 most likely had the same configuration.
Records of a number of 'Nahaufklärungsgruppen (NAG)' or Low Altitude Reconnaissance Wings/Squadrons, show a number of G-6/U3's in their ranks together with G-8's

The G-8 which was newly factory-built and did not have GM-1 nor MW-50; The G-8 Handbuch states :
'Teil 0 – Allgemeine Angaben / 7C – GM 1-Anlage - entfällt'

However, the G-6/U3's were modifications of existing G-6's, some of which were GM-1 equipped U2's.

GM-1 had some operational difficulties and as the DB 605 AS with improved (DB 603-) Supercharger came into service, it became obsolete. The AS engine's performance proved sufficient, so aircraft with the GM-1 installations (tanks) were logical candidates for modification to MW-50 as this involved minor adaptation.
Later, a lighter 'dedicated' MW-50 system also became available as this was standardly built into the G-14's.
This system was also retrofitted into some G-6/R2(3) High Altitude Recce aircraft that did not already have any 'Zusatzeinspritsung' (GM-1 or MW-50), but it is unlikely that it was incorporated into the U3, as they did not see the need to equip the G-8 with MW-50 either.
The fact that they did build it into some G-6's, was because these, by chance/availability, were G-6-U2's anyway and it may have been easier to convert the GM-1 system, than to remove it.

This does mean that the G-6/U3's and a number of converted U2's, were (only) equipped with the 20-30 kg , heavy, converted, 115 or 85 ltr GM-1 tanks, that used pressurized air bottles, placed in their right hand wing, to pressurize the MW-50 Tank.

Hi,

The conversion of GM 1 equipped Bf 109 aircraft to MW 50 operation was detailed in Daimler-Benz documents issued 20. 6. 1944, although earlier instructions are known, possibly 5. 6. 1944.
The modified system diagram for the GM 1 modification was issued by Daimler-Benz as, Skizze 9-605-6142 schematische Darstellung.
Unfortunately, it is unclear if the diagram you show is fully accurate to the 6142 document. It looks as though your diagram is possibly from J-C Mermet's illustrations?
It is clear in the DB documents that there were various modifications to the aircraft, engine and the old GM 1 system, to convert to MW 50 capability from the previous GM 1 capability.

Cheers

Eng

Shortways · Nov 8, 2025

Engineman said:
Hi,

The conversion of GM 1 equipped Bf 109 aircraft to MW 50 operation was detailed in Daimler-Benz documents issued 20. 6. 1944, although earlier instructions are known, possibly 5. 6. 1944.
The modified system diagram for the GM 1 modification was issued by Daimler-Benz as, Skizze 9-605-6142 schematische Darstellung.
Unfortunately, it is unclear if the diagram you show is fully accurate to the 6142 document. It looks as though your diagram is possibly from J-C Mermet's illustrations?
It is clear in the DB documents that there were various modifications to the aircraft, engine and the old GM 1 system, to convert to MW 50 capability from the previous GM 1 capability.

Cheers

Eng

Hi Eng,

Great! Original documents telling the truth.
Would be awesome if I could find them, but no luck yet. As far as my diagram is concerned; It is indeed in English. So you are probably right. So this Mermet made his own drawings?! I thought they would just be copies with English text. This is such a problem. It keeps diluting historical truth.

Engineman · Nov 8, 2025

Shortways said:
Hi Eng,

Great! Original documents telling the truth.
Would be awesome if I could find them, but no luck yet. As far as my diagram is concerned; It is indeed in English. So you are probably right. So this Mermet made his own drawings?! I thought they would just be copies with English text. This is such a problem. It keeps diluting historical truth.

Jean Claude Mermet has produced some great reproductions of Bf 109 information. His booklet from 1999 has much information. Unfortunately, his detail is not always the
exact original documents. You can find his 1999 booklet online.

Eng

Shortways · Nov 8, 2025

Shortways said:
Hi Eng,

Great! Original documents telling the truth.
Would be awesome if I could find them, but no luck yet. As far as my diagram is concerned; It is indeed in English. So you are probably right. So this Mermet made his own drawings?! I thought they would just be copies with English text. This is such a problem. It keeps diluting historical truth.

I think Udo Hafner has the documents.
I will find out soon.

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