"Slosh" or "Whine", Monsieur....? (ALLIED vs. AXIS Supercharger Drives)

[HoHun]

Hi Nicknick,

I don’t know every version of the Jumo 213, but the version I see in a picture does have an hydraulic coupling.

So which picture of which version in which book are you looking at?

The Jumo 213 A-1 according to the "Jumo 213 A-1 u. C-1 Motoren-Handbuch (Stand Mai 1944)" doesn't have a hydraulic coupling, but it does have an automatic engine control.

Regards,

Henning (HoHun)

 

[Nicknick]

All I can say, both pictures on page 419....(the secret horsepower race)

Does the 213 A-1 have a mecanical clutch?

 

[HoHun]

Hi Nicknick,

All I can say, both pictures on page 419....(the secret horsepower race)

The caption is "Jumo 213 J supercharger variations drawn by Friedrich Kosche for British Air Intelligence".

The Jumo 213 A-1 has a mechanical clutch, as clearly indicated in the "Jumo 213 A-1 u. C-1 Motoren-Handbuch (Stand Mai 1944)".

Regards,

Henning (HoHun)

 

[Nicknick]

according to this picture, it had a centrifugal clutch:

On superchargers, Mikulins, Klimovs, Jumos, etc

An issue raised above the shape of Jumo 213 power curve, both here and at Tony Williams' forum, made me dwell a bit about things mentioned in the title. Like I need any pretext... One member in each forum commented that power curve should begin, for a choosen power setting, from, say, 1500 HP...

ww2aircraft.net

might or might not have been the only one

There must have been good reasons to go on with the hydraulic couplings on later models...

 

[Nicknick]

according to this thread (https://www.flugzeugforum.de/threads/jumo-213-und-db-603.74846/page-5) it seems to me, that the two stage "laderschaltgetriebe" (the two stage gearbox for the supercharger without hydraulic) needed manual actuation, which fits very well to my theses, that the hydraulic couplings were preferd for automatisation ("Kommandogerät").

 

[HoHun]

Hi Nicknick,

according to this thread (https://www.flugzeugforum.de/threads/jumo-213-und-db-603.74846/page-5) it seems to me, that the two stage "laderschaltgetriebe" (the two stage gearbox for the supercharger without hydraulic) needed manual actuation, which fits very well to my theses, that the hydraulic couplings were preferd for automatisation ("Kommandogerät").

The chapter "Wirkungsweise der Schaltgetriebe-Automatik" ('Functioning of the Automatic Gearbox') in the engine manual mentions a control to override the automatic - so it's not impossible to switch manually, but the standard mode of gearbox operation was automatic (and it only allowed manual override in part of the evelope).

This device needs steady functions for the air and fuel flow and switching would have been an issue which couldn’t be solved by atomization.

It could be solved, and it was.

Regards,

Henning (HoHun)

 

[Nicknick]

Seems like it wasn’t entirely satisfactory, so that Junkers also switched to hydraulic couplings. There must have been a sudden loss of power for a short moment, every time the clutch switched the gear, for sure one reason for the manual option (not helpful in a dogfight…).

As said, hydraulic variable speed also helps to reduce the charge temperature, which rises power in all situations were full boost pressure cant be applied before the maximum altitude for the specific gear will be reached.

 

[HoHun]

Hi Nicknick,

Seems like it wasn’t entirely satisfactory, so that Junkers also switched to hydraulic couplings. There must have been a sudden loss of power for a short moment, every time the clutch switched the gear, for sure one reason for the manual option (not helpful in a dogfight…).

I guess you're unaware that the Jumo 213J was meant to provide a massive performance improvement over the previous versions, so it's impossible to insinuate that any particular change was addressing a shortcoming of those versions.

Do you have any evidence for the alleged "sudden loss of power", at all?

Regards,

Henning (HoHun)

 

[Nicknick]

he 213 J had the hydraulic couplings/torque converters, this was certainly an enabler of better performance, so I don’t see any contradiction in this.

Smooth gear switching methods became available with hydraulic couplings and torque converters, there was no way for smooth gear shifting with mechanical clutches. Every gear shift must have lead to a sudden change in supercharger rpm which causes a power drop when the rpm is decreased an also a drop in engine rpm if the supercharger speed is increased. No doubt, the hydraulic/mechanic engine control system needed additionally some time to readjust after a sudden change in supercharger rpm.

 

[HoHun]

Hi Nicknick,

he 213 J had the hydraulic couplings/torque converters, this was certainly an enabler of better performance, so I don’t see any contradiction in this.

I wasn't pointing out out a contradiction, I was pointing out a lack of conclusiveness. You said ...

Seems like it wasn’t entirely satisfactory, so that Junkers also switched to hydraulic couplings.

Junkers were using every trick in the book to improve performance, so you can not interprete the addition of hydraulic couplings the Jumo 213J as an indication that the fixed gearing on the Jumo 213A, E and F was unsatisfactory in operation, or had a problem that couldn't be solved with automation.

In your own words:

This device needs steady functions for the air and fuel flow and switching would have been an issue which couldn’t be solved by atomization.

Jumo 213A, E and F had automatic engine controls and worked just fine without a hydraulic coupling. The engine control device didn't need nice steady functions, and these engines were perfectly fit for combat operations even when these involved switching supercharger gears.

So the entire "issue" seems to be completely imaginary, invented by you personally, with not even an attempt to actually find evidence that anyone in WW2, pilot or engineer, ever noticed a problem.

Regards,

Henning (HoHun)

 

[Nicknick]

This discussion leads to nothing, I could go on trying to explain, why such a device like the Kommandogerät is unable to react to sudden changes and you can go on saying it will. Of course there is no clear yes and no answer of hao bad engine performance was affected during a sudden switch in the supercharger drive system.

As long as pilots didn’t even know, there might be a better alternative to mechanical switching, no one will complain. Like in the first automobiles, people saw no problem in handcranking or unsynchronized gearboxes, but after knowing the better alternatives (like automatic transmission with torque converters or at least hydraulic couplings) there was no way back…

 

[HoHun]

Hi Nicknick,

This discussion leads to nothing, I could go on trying to explain, why such a device like the Kommandogerät is unable to react to sudden changes and you can go on saying it will.

Your original suggestion has been that gear changes pose an irresolvable issue for automatic engine controls that induced German engineers to embrace hydraulic couplings, in particular Jumo engineers with the Jumo 213.

That's complete and utter fantasy, based on no facts or sources from the real world.

Not to say that at least half of what you say isn't perfectly sensible if viewed in isolation, but none of it actually supports your point even though it might be technically correct. That's a bit like the "apes on a typewriter composing Shakespeare" approach ... dropping random bits of self-evident facts might work in the end, but it's not quickest way to get there.

Regards,

Henning (HoHun)

 

[Nicknick]

I formulated a thesis for discussion, so I don’t have to bring absolute evidence for that. I still find it pretty convincing, that the idea of using hydraulic couplings was developed because of the automatization. It is very disappointing in a dogfight, if you loose power even for 3 seconds because of an unforeseeable gearswitch.

You cant proof your denial on any hard facts either, same as I, but still my thesis is logic and historic facts support it (which is different than proving it).

 

[HoHun]

Hi Nicknick,

You cant proof your denial on any hard facts, same as I, but still my thesis is logic and historic facts support it (which is different than proving it).

If you claim something, the burden of proof lies with you.

This part of the forum is called "Research Topics", not "Let Your Imagination Run Wild Unquestionedly".

If you actually do research and find those "historic facts that support it", come back with those facts, and I'll be happy to discuss them in detail.

Until then, I'm not interested, and not fine with you passing of your freely invented "thesis" as factual.

Regards,

Henning (HoHun)

 

[Nicknick]

If you scroll back, you might notice that I started my thesis with “I’m pretty sure that (…)” and not with “I have evidence that (…)”. This is a discussion board and not a fact sheet.

However, I listed enough indication to make this theory plausible.

For not being interested you posted quite a lot…