Making the best use of Jumo 211 series?

[tomo pauk]

The workhorse engine of the LW in the ww2, powering many important aircraft both during the initial victories and the later defeats. Never gaining the 'star' status like the DB or the BMW 801 engines had, despite it's ubiquity; granted, on the production lines it was pretty much replaced by the Jumo 213s by 1944.
Rumor has it that crates upon crates of the engines were left in Germany in 1945, since it was not needed anymore (?).

What steps might've been the useful steps in making it a more important engine? Plausible improvements to make it more attractive?
Perhaps also shipping it to the Axis allies to improve/re-engine their A/C (using the fighters like the IAR 80/81s, G.50s and MS 406 was beyond the sell date already by 1941/42)? Romanians have had a good thing going on with the Jumo-powered IAR 81 prototype, just for it to be killed by the Germans not playing the ball - M mack8 .
Note that the B4 fuel is still a given.

 

[SaparotRob]

I can't answer your query but finding crates of "new" 70 plus year old engines would be cool!

 

[tomo pauk]

The easiest way for the 211s to gain some additional ... notoriety might've been to start sending them to Italy, once there is a realization that Italy will be ill able to produce the modern engines in the required quantity. This means making more of the fighters in that can do about 600 km/h, from Macchi, Fiat and Reggianne; the later company reverted to the indifferent radials engines after the Re.2001 because the supply of DB 601s was insufficient.
This way also perhaps the Fiat G.50V or the Ro.58 might've also materialize as a service-worthy aircraft, even if the engines used are from Jumo and not from DB.
Romanians installing the 211 on their IAR fighters was discussed on this forum before.

This shuffling of the engines would've certainly meant that there is less of Jumo 211 engines for Germany, meaning for example that the Ju 87 production is even faster curtailed.

 

[Zmauky]

Lots of ideas where the excess engine could be used.
It's just a matter of when.
If we are talking about 1944 (and probably these surpluses were caused by the cessation of bomber production) then the number of ideas very quickly boils down to why they were surplus.
( Too ) weak for fighters (Avia S-199 ?) and all extra Ju 88A, He 111, Ju 87 or Ju 290 or Ju 352 would just become pennants/stars drawn on allied fighters.
And then when it could have meant something, they weren't there. For example to replace the He 111 (with DB 600) '38 or the Do 215 '40 (to release DB for fighters) even the He 112 as the second basic fighter in 1939-1941. And yes for all minor axis AF.

 

[tomo pauk]

( Too ) weak for fighters (Avia S-199 ?) and all extra Ju 88A, He 111, Ju 87 or Ju 290 or Ju 352 would just become pennants/stars drawn on allied fighters.

Avia S-199 was an example of how to make an underperformer. Post-war, the Czechs mated the draggy 109G-6 airframe with an engine that was okay in 1941-42 (the Jumo 211F), but it was badly obsolete already in 1943.
Mate a streamlined airframe (109F/G-2, MC.202, G.55V) with the 211F in 1941 and there is a competitive fighter to be had for 1941-42. Even makes sense on the bigger Re.2001, considering the 10-20% power increase over the DB 601A.
Move to the 211N by 1943 gets another 5-10% better power values (greater %-age at higher altitudes).

And then when it could have meant something, they weren't there. For example to replace the He 111 (with DB 600) '38 or the Do 215 '40 (to release DB for fighters) even the He 112 as the second basic fighter in 1939-1941.

A second iron in the fire in the shape of the 211-powered He 112 certainly looks like a no-nonsense fighter.

The engine itself could've used a bit of ... love. Like outfitting it with the swirl throttle for more power under ~5 km without the need for the hi-oct fuel - book about the Me 309 by Sharp and Douglas notes that Jumo 213 was already with the swirl throttle during the test phases in the late 1941. A 'proper' rating of the 211 series for Notleistung rpm and boost, even if it is just for 3 minutes, would've helped with power at all altitudes.

Coming out sooner with something akin to the 211R version, that traded low-alt power for high-alt power increase would've also helped.

 

[z42]

• Could a "213-lite" engine have been available earlier if they just had added a 4V head to the 211? (Also the pressurized cooling system, but this was already implemented in later 211 variants.)
• A transport plane with two 211's and steel tube+fabric+wood construction instead of the Ju 52.

 

[tomo pauk]

Could a "213-lite" engine have been available earlier if they just had added a 4V head to the 211? (Also the pressurized cooling system, but this was already implemented in later 211 variants.)

The 211R + swirl throttle = 213 lite?
As-is, it was supposed to be making 1200+ PS at 7100m, comparing with with the 213A at 3000 rpm making 1300+ PS there. At 3km, the 211R was supposed to do ~1480 PS, where the 213A was doing the same at 3000 rpm. Swirl throttle takes care of the 'gaps' that were present with the 211R, namely down low (213A @3000 rpm has extra ~130 PS at SL), and between 4 and 6 km (213A @3000rpm has about 200 PS extra).

(my humble opinion is that the supposed disadvantage of the 3-valve head for the Jumo engines is sometimes overblown)

 

[tonycat77]

A detuned version for tank production, by 1940 would be nice, Germany would get a 500-600hp class engine with similar size to the v2-34 which was derived from 1920s German aerial engine development anyway, send damaged or worn out engines to a Maybach plant to make them into a German meteor engine.

 

[tomo pauk]

Interestingly enough, there was several attempts on installing the Jumo 211 engines on the Bf 109, and some of them even flew, at least per this post on another forum (can be translated easily), also here for the facsimile of the original doc about the Dec 1942 meeting. The doc hopes for a 100 rpm increase of the 211J engine vs. what is normally making, so it can make 'a bit better power' than the DB 601E down low, while still having a 70 PS deficit at 'altitudes' ('Hoechenbereich').

The doc states the 50 km/h deficit vs. the 'normal' Bf 109F-4 - pretty sobering, although it is probably in case if the 'normal' 211J was installed, that was about 10-15% less powerful at altitude than the DB 601E. I'm also not sure why the intercooled engine is used, instead of the non-intercooled sibling, ie. 211F; intercooler will add a bit of drag, but it will also add some power.

 

[Luft.4]

Maybe this could be of some use ... or at least enough to continue scratching your heads.
Based on decoding the engine number, it is actually a Jumo 211. In my database, a lot of 129 batch Jumo 211 engines were built as F2 sub-models.
Alternatively, it could just be a typist error.

 

[tomo pauk]

Could a "213-lite" engine have been available earlier if they just had added a 4V head to the 211? (Also the pressurized cooling system, but this was already implemented in later 211 variants.)

On the theme of '213 lite' - Jumo was mooting different types of supercharging for the 213 as early as 1941, including 2-stage S/C.
(they were also mooting the - very elusive - the versions with '1-stage supercharger with axial pre-stage without intercooler', that sound suspiciously like the S-P supercharger that Turbomeca in France made for the HS-12Y-45 and on)

My idea is that a 2-stage S/C on the Jumo 211 would've been a crucial step in making that engine a really competitive one. Not a super engine by any means, but a significant improvement. Intercooler is IMO mandatory, sprinkle a bit with MW 50 and/or swirl throttle as these are available.
Trying the 211 out with the S-P supercharger would've also been interesting.

 

[tonycat77]

On the theme of '213 lite' - Jumo was mooting different types of supercharging for the 213 as early as 1941, including 2-stage S/C.
(they were also mooting the - very elusive - the versions with '1-stage supercharger with axial pre-stage without intercooler', that sound suspiciously like the S-P supercharger that Turbomeca in France made for the HS-12Y-45 and on)

My idea is that a 2-stage S/C on the Jumo 211 would've been a crucial step in making that engine a really competitive one. Not a super engine by any means, but a significant improvement. Intercooler is IMO mandatory, sprinkle a bit with MW 50 and/or swirl throttle as these are available.
Trying the 211 out with the S-P supercharger would've also been interesting.

Couldn't they add the DB supercharger system?

 

[tomo pauk]

Couldn't they add the DB supercharger system?

They probably could.
Advantages of the variable speed drive for the S/C vs. the 2-speed drive was that the power loss between the 1st and second gear is less prominent.
See here the 30 min power graph for the Jumo 211F (thick black line) and the DB 601E (red line). Variable speed drive will add as much as 100+ HP vs. the 'normal' 2-speed drive, atop to the 601E already making extra 80-100 HP (partially due to running 2500 rpm on the 30 min power setting, vs. the 211F running on 2400, and partially because it was a 4-valve head vs. the 3-valve head?).
Disadvantage of the variable speed drive was the increased heating of the engine oil under the rated altitude, sue to the slippage within the drive - the oil system will need a bigger radiator.



What both DB and Jumo engines will need is a much better S/C by some time of winter 1942/43, let alone by Summer of 1943.

 

[mack8]

The workhorse engine of the LW in the ww2, powering many important aircraft both during the initial victories and the later defeats. Never gaining the 'star' status like the DB or the BMW 801 engines had, despite it's ubiquity; granted, on the production lines it was pretty much replaced by the Jumo 213s by 1944.
Rumor has it that crates upon crates of the engines were left in Germany in 1945, since it was not needed anymore (?).

What steps might've been the useful steps in making it a more important engine? Plausible improvements to make it more attractive?
Perhaps also shipping it to the Axis allies to improve/re-engine their A/C (using the fighters like the IAR 80/81s, G.50s and MS 406 was beyond the sell date already by 1941/42)? Romanians have had a good thing going on with the Jumo-powered IAR 81 prototype, just for it to be killed by the Germans not playing the ball - M mack8 .
Note that the B4 fuel is still a given.

As i touched in the past i believe, there is a bit of unclarity whether the IAR-80 ever flew with a Jumo-211 (it did flew with DB-601A and DB-605A). However the Jumo-211 was the preferred choice for IAR-80 and SM-79 from as far back as 1937 if we go by romanian books/info. Estimated IAR-80 performance with a Jumo-211 was a speed at least 30 kph higher vs the radial version (558 kph at 5700m vs 528 kph at 4000m for the IAR K-14 variant), but again it's a bit unclear which Jumo-211 version this estimate is for, is it A (which was obviously the only one available in 1937), or D as the romanian sources claim. The power is given as 930HP at 5700 m for the Jumo-211D, is this accurate? Estimated weight increase was 200 kg if fitted with the Jumo. Finally, it was judged that the radial version would actually be superior up to 4000 m compared to the Jumo version, which i find questionable. Perhaps might be the case if they were referring to Jumo-211A?

At any rate, given that there were at least 7000 Jumo-211 rotting in depots, actually using those would be a good start. Indeed give them to the italians to put on the Reggianes (leaving DBs for the Fiats and Macchis), and give them the licence too (though they literally need to force the italian MIC at gunpoint to do so, given the nepotism and turfism prevalent there- Isotta Fraschini would be so much more useful for the war effort building Jumo-211s instead of the useless air cooled inlines of OTL). By extension, if the hungarians still build Re-2000s they might be fitted with Jumo-211s too. One can guesstimated a similar increase in performance for the Jumo Reggianes as with the Jumo IAR-80.

Probably, just like the JRS-79B, italian twin engine bombers will be feasible with Jumo-211 as well, either a BR-20 variant or a Z-1018 variant or even an italian JRS-79 etc.

 

[mack8]

Interestingly enough, there was several attempts on installing the Jumo 211 engines on the Bf 109, and some of them even flew, at least per this post on another forum (can be translated easily), also here for the facsimile of the original doc about the Dec 1942 meeting. The doc hopes for a 100 rpm increase of the 211J engine vs. what is normally making, so it can make 'a bit better power' than the DB 601E down low, while still having a 70 PS deficit at 'altitudes' ('Hoechenbereich').

The doc states the 50 km/h deficit vs. the 'normal' Bf 109F-4 - pretty sobering, although it is probably in case if the 'normal' 211J was installed, that was about 10-15% less powerful at altitude than the DB 601E. I'm also not sure why the intercooled engine is used, instead of the non-intercooled sibling, ie. 211F; intercooler will add a bit of drag, but it will also add some power.

Could it be that the 50 kph decrease was because the Jumo-211 Bf-109 had to use the gunpods, just like S-199 did? What's the speed difference between S-199 and fully rated Bf-109G-6 with the gunpods? That would perhaps be a better yardstick to judge speed difference.
Aiui, S-199 terrible handling was in good part due to using as-is the bomber prop and gear ratio on the Jumo-211, hence too much torque. A fighter suitable reduction ratio and prop on the Jumo-211, maybe same VDMs like on the normal 109s, might alleviate the handling issues as well as give a bit more performance?

 

[tomo pauk]

The power is given as 930HP at 5700 m for the Jumo-211D, is this accurate? Estimated weight increase was 200 kg if fitted with the Jumo. Finally, it was judged that the radial version would actually be superior up to 4000 m compared to the Jumo version, which i find questionable. Perhaps might be the case if they were referring to Jumo-211A?

See here for the 211A: graph
Here are the other 211 graphs that I've had at the time: link
The 211B was making the same power as the 211D, FWIW.

At any rate, given that there were at least 7000 Jumo-211 rotting in depots, actually using those would be a good start. Indeed give them to the italians to put o the Reggianes (leaving DBs for the Fiat and Macchis), and give them the licence too (though they literally need to force the italian MIC at gunpoint to do so, given the nepotism and turfism prevalent there- Isotta Fraschini would be so much more useful for the war effort building Jumo-211s instead of the useless air cooled inlines of OTL). By extension, if the hungarians still build Re-2000s they might be fitted with Jumo-211s too. One can guesstimated a similar increase in performance for the Jumo Reggianes as with the Jumo IAR-80.
Probably, just like the JRS-79B, italian twin engine bombers will be feasible with Jumo-211 as well, either a BR-20 variant or a Z-1018 variant or even an italian JRS-79 etc.

Considering what the Italians, Romanians and Hungarians were mostly installing on their fighters, Jumo 211 would've been a better/much better choice than these.
I-F making the 211 under licence is a very sound suggestion.

Could it be that the 50 kph decrease was because the Jumo-211 Bf-109 had to use the gunpods, just like S-199 did?

Too early to call without taking a peek in the actual docs, wrt. the 211-powered German Bf 109.

 

[mack8]

See here for the 211A: graph
Here are the other 211 graphs that I've had at the time: link
The 211B was making the same power as the 211D, FWIW.



Considering what the Italians, Romanians and Hungarians were mostly installing on their fighters, Jumo 211 would've been a better/much better choice than these.
I-F making the 211 under licence is a very sound suggestion.



Too early to call without taking a peek in the actual docs, wrt. the 211-powered German Bf 109.

Thanks for the graphs/details, so indeed it seems the romanians were using Jumo-211D specs as the benchmark. So in this TL IAR-80 and Re-2000 Jumo variants are roughly 540-550kph fighters, with better altitude performance compared to GR 14K derivatives of OTL. Later on fitting the Jumo-211F and other more developed variants possible in this TL would bring a further boost in speed.

On the theme of '213 lite' - Jumo was mooting different types of supercharging for the 213 as early as 1941, including 2-stage S/C.
(they were also mooting the - very elusive - the versions with '1-stage supercharger with axial pre-stage without intercooler', that sound suspiciously like the S-P supercharger that Turbomeca in France made for the HS-12Y-45 and on)

My idea is that a 2-stage S/C on the Jumo 211 would've been a crucial step in making that engine a really competitive one. Not a super engine by any means, but a significant improvement. Intercooler is IMO mandatory, sprinkle a bit with MW 50 and/or swirl throttle as these are available.
Trying the 211 out with the S-P supercharger would've also been interesting.

I touched elsewhere on my idea of an alternate Jumo-213, which is basically a bored out to 155mm Jumo-211, with another 100 rpm and whatever supercharger improvements feasible, basically what DB did with the DB-605. The DB thus got another 125 PS, so if Jumo gains roughly the same, it means about 1460 PS for a bored 211F, 1540 PS for a bored 211J, 1570 PS for N and 1620 PS for P.

Given the troublesome Jumo-213 gestation due to it's advanced construction especially high rpm, getting about 1600 PS in 1942 from a bored 211 might worth more that getting 1750 PS from the Jumo-213 in 1944?

Also considering the OTL Jumo-211 overproduction, that might as well be allowed to continue, presumably switching to a bored Jumo-211 would be easier than to the brand new OTL Jumo-213, so more engines can be built, say instead of the 9000 or so Jumo-213, we get 20,000 or even 30,000 bored Jumo-211s instead (this partially obtained from switching part of the late Jumo-211 production to the bored variant).

 

[peceed]

Let's make a DB-606/610 equivalent using counter-rotating propellers.

I touched elsewhere on my idea of an alternate Jumo-213, which is basically a bored out to 155mm Jumo-211

Such a change requires designing a completely new engine: new block, new pistons, new cylinders, for +5% performance boost only. The old inefficient valve layout remains - which is supposed to deliver more mixture to the pistons. Futile.

I strongly prefer the use of an improved compressor with Polikovsky vanes - simple and efficient.

and give them the licence too

What's the point of licensing an inferior engine?