Confusing description about MBG emergency mode handle in manual

[dcn]

This has confused me for about 3 years.It says 'In normal position the MBG operates in automatic mode.In case of emergency,the handle can be pulled to allow the engine to operate at higher boost pressure than normal',but then it says 'When flying in 'Notzug' mode,boost pressure of 1.55 ATA should never be exceeded!When flying in 'Notzug' mode,engine speed of 2700 RPM should never be exceeded!',this is paradoxical.It also says 'The MBG emergency mode handle switches the MBG to manual operation by cutting off pressurised oil.In case of MBG malfunction,it allows to proceed flight using the manual throttle valve.Normally,this throttle fully opens at 40 degrees of the throttle giving room for further automatic control.In manual mode,its range is extended up to 90 degrees or full throttle level range.Due to engine overstressing,the throttle must not be advanced beyond 2700 RPM or 60 degrees of its travel.',this is paradoxical too.And the 40 degrees of fully opend normal throttle position seems strange,in the table,40 degrees of throttle position only gives about 2300 RPM,does this mean engine speed can only reach about 2300 RPM at full throttle position with MBG emergency mode handle not pulled?And in the table,it says the engine has an emergency power(increased take-off power) at 3250 RPM for permissiable 3 min when throttle position is at 90º command angle,and the engine has a take-off,combat and climb power at 3250 RPM for permissiable 30 min when throttle position is at 90º command angle but it didn't say how to enable emergency power(increased take-off power).Then I found an old version of the manual,it says 'Emergency Power(increased take-off power) 3250 RPM only below 1000m on 213A-G1 by pulling the MBG-emergency pull or as intermediary solution on 213-A RS by operation of a cock in the manifold pressure line.Hereby the manifold pressure increase by 0.2 ata while maintaining constant engine speed/RPM.',why is this description deleted in present manual?Why pulling the MBG emergency mode handle can enable emergency power(increased take-off power)?Didn't it say 'When flying in 'Notzug' mode,boost pressure of 1.55 ATA should never be exceeded!When flying in 'Notzug' mode,engine speed of 2700 RPM should never be exceeded!'?

In game test:

Full throttle,MBG emergency mode handle not pulled,MW-50 not enabled

Full throttle,MBG emergency mode handle pulled,MW-50 not enabled

Full throttle,MBG emergency mode handle not pulled,MW-50 enabled

Full throttle,MBG emergency mode handle pulled,MW-50 enabled

Description about MBG emergency mode handle in manual

Description about power settings in present manual

Description about power settings in old manual

Edited August 26, 2022 by dcn

[grafspee]

In MGB emergency mode you can operate engine at higher ATA but you are limited to 1.55 and 2700 rpm what is confusing here i don't know.

Max power isn't available no longer because engine control unit is turned off.

MGB mode allow you to use higher ATA for low rpm range for example if you want to pull a little more ATA when cruising at low rpm.

 I haven't tested it but if you can do 1.55 ata at 2700rpm at emergency mode it is a lot more what you have in automatic mode.

 

Edited August 26, 2022 by grafspee

[kablamoman]

I think this is an issue with the description/translation in the manual.

The way its worded implies that the handle is used as a kind of "WEP" for extra boost, but it's really just a mechanical backup to the main MBG in the event that it is damaged, or it otherwise fails. Although the description implies you can achieve higher power settings (this may be true for specific RPM values), you are still limited overall in the back up mechanical mode compared to what you could achieve with a fully-functioning hydro-mechanical MBG unit.

TL;DR: Use it only if the MBG fails and your engine is not responding normally. When you do so, ideally you pull the handle after first selecting idle power, and then once switched over you have to respect the lower power limits while you're limping back to home plate.

Edited August 23, 2023 by kablamoman

[grafspee]

@kablamoman Yes you are right. In some cases DCS's manuals looks like mixed pieces of information often not 100% accurate.

Every time i converse with @Yo-Yo or other ED stuff i am asked to refer only to original documents and not to DCS's manuals.

[dcn]

2023/8/23 AM12点28分，kablamoman说：

I think this is an issue with the description/translation in the manual.

The way its worded implies that the handle is used as a kind of "WEP" for extra boost, but it's really just a mechanical backup to the main MBG in the even that it is damaged, or it otherwise fails. Although the description implies you can achieve higher power settings (this may be true for specific RPM values), you are still limited overall in the back up mechanical mode compared to what you could achieve with a fully-functioning hydro-mechanical MBG unit.

TL;DR: Use it only if the MBG fails and your engine is not responding normally. When you do so, ideally you pull the handle after first selecting idle power, and then once switched over you have to respect the lower power limits while you're limping back to home plate.

Would appreciate it if you could send me the manual of Fw 190 D-9 or Jumo 213 A.In the game pulling the MBG emergency mode handle has similar effect as enabling MW-50,if it is true as you said,that's strange.

[saburo_cz]

[kablamoman]

10 hours ago, dcn said:

Would appreciate it if you could send me the manual of Fw 190 D-9 or Jumo 213 A.In the game pulling the MBG emergency mode handle has similar effect as enabling MW-50,if it is true as you said,that's strange.

I don't have the manual myself, but it looks like @saburo_cz posted an excerpt above.

Here's another excerpt, but this from a copy the TA-152 pilot's notes (also using the Jumo 213):

Translation:

Engine Malfunctions,

as a result of failure of the automatic control system in the Engine Control Unit;

Engine seizes or runs erratically:

1. Pull back the power lever.
2. Emergency handle for Engine Control Gearbox... "Pull".
3. Do not exceed boost pressure of 1.55 ata.

 

Another interesting note about the handle is that it was pulled for cold starts (and easier starting in general). As I understand it, the emergency handle, when pulled, allowed the power lever direct mechanical control of the idle throttle valve on a different schedule than when in automatic mode (where its use was coordinated the oil-actuated filling throttle at the supercharger) and that ended up working better for cold starts.

Another interesting tidbit is that when pulled, the handle should catch on teeth along the shaft. To push the handle back in, the pilot first had to rotate it 90 degrees to the right to unlock it before stowing it again (as seen here) :

 

 

 

 

Edited August 24, 2023 by kablamoman

[kablamoman]

11 hours ago, dcn said:

In the game pulling the MBG emergency mode handle has similar effect as enabling MW-50,if it is true as you said,that's strange.

Regarding the effect of pulling the handle:

 

As I understand it, the idle throttle being under direct control of the power lever and opening on a different schedule than it would in the regular automatic mode, coupled with the lack of automatic metering for the "filling" throttle at the supercharger (oil-actuated) could result in a boost to ata compared to when the automatic mode is engaged.

The reason for the 2700 RPM/1.55 ata limit in the manual mode is that there was the danger of over-boosting the engine and causing critical damage. Whether or not any of this is modeled in the sim, I'm not sure, but it's clear from those limits that the emergency handle is not a "WEP" handle used to get away from bandits -- unless you like running away with your RPM at 2700 as opposed to 3250. There is a post from 2014 in the forums by the original manual writers seeking information about the MBG that also seems to express some confusion about the emergency handle, so that may be partly why the manual is so confusing.

Edited August 24, 2023 by kablamoman

[peachmonkey]

7 minutes ago, kablamoman said:

danger of over-boosting the engine and causing critical damage. Whether or not any of this is modeled in the sim, I'm not sure

something is definitely modeled, if you pull the lever and firewall the throttle the engine will die in about 1-2 minutes...

[dcn]

Thanks for you guys' information.Still confused about how to enable emergency power(increased take off power) which could last 3 min.

3小时前，peachmonkey说：

something is definitely modeled, if you pull the lever and firewall the throttle the engine will die in about 1-2 minutes...

Didn't test it for how long it could last.

Edited August 24, 2023 by dcn

[kablamoman]

4 hours ago, dcn said:

Thanks for you guys' information.Still confused about how to enable emergency power(increased take off power) which could last 3 min.

I think this is another issue with the manual that snuck in due to changing specifications throughout the war. This video may help clear things up for you (or confuse you even more):

 

The long and short of it is that for a brief period of about 2 months at the end of '44 (more details here), there was a 3 minute "increased take-off power" spec ("Sonderstartspitze") that was useable up to 500m that was activated by the Notzug pull handle (bowden cable in the video). The Jumo engines that were approved for this were designated 213 A G-1, but this designation was soon revoked when the engine regime was found to be unreliable, and the Notzug mode for the MBG was again restricted to 2700 RPM/1.55 ata.

Edited August 24, 2023 by kablamoman

[saburo_cz]

8 hours ago, dcn said:

Still confused about how to enable emergency power(increased take off power) which could last 3 min.

You can't enable it.

It is not possible to activate something what does not exist.

It is only mistake in DCS manual.

[dcn]

6小时前，kablamoman说：

I think this is another issue with the manual that snuck in due to changing specifications throughout the war. This video may help clear things up for you (or confuse you even more):

 

The long and short of it is that for a brief period of about 2 months at the end of '44 (more details here), there was a 3 minute "increased take-off power" spec ("Sonderstartspitze") that was useable up to 500m that was activated by the Notzug pull handle (bowden cable in the video). The Jumo engines that were approved for this were designated 213 A G-1, but this designation was soon revoked when the engine regime was found to be unreliable, and the Notzug mode for the MBG was again restricted to 2700 RPM/1.55 ata.

 

It's so nice of you,thank you!

2022/8/26 PM1点32分，dcn说：

The MBG emergency mode handle switches the MBG to manual operation by cutting off pressurised oil.In case of MBG malfunction,it allows to proceed flight using the manual throttle valve.Normally,this throttle fully opens at 40 degrees of the throttle giving room for further automatic control.In manual mode,its range is extended up to 90 degrees or full throttle level range.Due to engine overstressing,the throttle must not be advanced beyond 2700 RPM or 60 degrees of its travel.

The 40 degrees of fully opend normal throttle position seems strange,in the table,40 degrees of throttle position only gives about 2300 RPM,does this mean engine speed can only reach about 2300 RPM at full throttle position with MBG emergency mode handle not pulled?

Edited August 24, 2023 by dcn

[peachmonkey]

4 hours ago, dcn said:

It's so nice of you,thank you!

The 40 degrees of fully opend normal throttle position seems strange,in the table,40 degrees of throttle position only gives about 2300 RPM,does this mean engine speed can only reach about 2300 RPM at full throttle position with MBG emergency mode handle not pulled?

 

I think checking the veracity of the DCS manual is a tedious affair.

"throttle fully opens at 40 degrees of the throttle giving room for further automatic control"  <-- I don't quite understand what they mean by the bold part exactly, but I assume that the MBG 'komputer' in normal mode takes over the throttle flap/manifold/fuel mix/RPM regulation after you advance the throttle lever 40 degrees forward. Meaning you can still move the throttle further past 40 degrees to get the higher engine performance, but all linkage/throttle flaps/fuel mix/rpm is under control of the mechanical MBG device.

In Manual mode (emergency lever pulled) the MBG automation does not work, hence you have a direct control of the throttle flap (?) mechanism (up to 90 degree of throttle lever position). Since throttle/RPM are linked together (in auto or manual mode), the operation of the engine in manual mode does not seem any more different than in auto mode, except for the part that with MBG in manual mode there's no pressurized oil (which oil and why it has to be pressurized I have no idea) that leads to the premature engine's death if you run it past 1.55ata and 2700 RPM for longer that 1-3 minutes. Since MBG (or Kommandogerät in A8) controls the fuel mixture as well, I wonder if with MBG in manual the fuel mix is set to some static super lean mode that it creates detonation in the engine if it goes past 1.55ata/2700 rpm causing the death of the engine.

But of course I can be totally off with my analysis.

Edited August 24, 2023 by peachmonkey

[kablamoman]

7 hours ago, dcn said:

The 40 degrees of fully opend normal throttle position seems strange,in the table,40 degrees of throttle position only gives about 2300 RPM,does this mean engine speed can only reach about 2300 RPM at full throttle position with MBG emergency mode handle not pulled?

It's a bit more complicated than the DCS manual implies.

The Jumo 213 manual describes two separate throttling mechanisms. The primary one, that is used through most of the operating range, and the one that the MBG is able to actuate via oil pressure, is the "filling" throttle, sometimes refered to as the "swirl" throttle in the manual. This is part of the induction system at the supercharger.

They found that at lower power settings, this method of throttling did not work as efficiently so there is also a separate low speed, "idle" throttle and it is this one that is mechanically linked to the power lever and changes schedule when the notzug handle is pulled. I am assuming that when the oil pressure in the MBG is dumped when the notzug handle is pulled, the hydro-mechanically actuated filling throttle is left open at some arbitrary amount (in normal operation it would be carefully and deliberately metered by the MBG/Engine Control Unit), and primary modulation is instead obtained directly via mechanical connection to the idle throttle. Due to the power limitations when operating in this mode, I think it is safe to assume this method is less efficient, and can result in the combined effects of the non-responsive "filling" throttle and idle throttle creating overboost situations, or perhaps other problems with ignition timing or fuel mixture problems when the power lever position is too far forward.

Edited August 24, 2023 by kablamoman

[Yo-Yo]

The swirl throttle is not a throttle in general, it is a device that changes charger capacity instead of throttling. It gives advantage at altitudes lower than critical.
IN manual mode the charger works as a plain charger and the MP is throttled with the idle throttle as in plain engine.

I'd like to remind that MBG works very different comparing to Bendix-Stromberg carb or BMW-801 KG. MBG meters scheduled fuel and meters air mass flow to have required fuel-air ratio  and only when the charger capacity reaches 100% it begins to meter fuel to preserve fuel-air ratio.

[saburo_cz]

Here are two pictures showing "swirl throttle" from handbuch. These "flaps - Leitschaufel" control air volume passing through supercharger.

And youtube video where Calum Douglas explains basic about "swirl throttle"

 

[kablamoman]

8 hours ago, saburo_cz said:

Here are two pictures showing "swirl throttle" from handbuch. These "flaps - Leitschaufel" control air volume passing through supercharger.

[...]

And youtube video where Calum Douglas explains basic about "swirl throttle"

 

Great video, thanks for sharing!

[dcn]

Thank you guys!