Dec 1941 RLM decision. Produce BMW 801. Cancel Jumo 222.

[Denniss]

The Jumo 222 should have been dropped far earlier to free up money and manpower for Jumo 211/213 and 004 development.
To many highly complicated multibank engines were developed but not worth the money wasted there. It would have been easier to use the 211 and gor the 213 route with more RPM or go the DB601->603 route with larger displacement.

 

[wuzak]

He-219 night fighter. Flew fine with DB 610s, if a little underpowered. Follow on 219B was to have 222s, but only a handful of aircraft were made, and the unreliability of the 222 reared its head again

You mean DB603s?

If it had been fitted with DB610s I'm sure it woudln't have been underpowered.

 

[davebender]

I disagree. During 1942 no German aircraft engine produced more then 1,750 hp. Even late war German engines stopped at about 2,000 hp. A Jumo 222 engine which produced 2,000 hp during 1942 and 2,500 hp during 1945 would have been outstanding.

Dr. Tank would have been thrilled to have Jumo 222A engines for the Fw-190 program. So would Dornier for the Do-217 bomber (which becomes a Do-317 with Jumo 222 engines). Heinkel would have done backflips if RLM had provided him with Jumo 222A engines for the He-177B heavy bomber and He-219 night fighter.

Demanding even more power from the Jumo 222 was just one of many strange RLM engine decisions.

 

[johnbr]

What about putting people on the BMW 802 and axing the BMW 803.

 

[Jabberwocky]

Jumo 222 had to be re-designed for more power.

I disagree. During 1942 no German aircraft engine produced more then 1,750 hp. Even late war German engines stopped at about 2,000 hp. A Jumo 222 engine which produced 2,000 hp during 1942 and 2,500 hp during 1945 would have been outstanding.

No German SERVICE engine in 1942. However, there were a number of experimental/prototype designs that were producing more than 2000 PS, including the DB 604 (cancelled during 1942), DB 606 and Jumo 213B, as well as the various twinned DB 603 designs, most of which ended up being abandoned in late 1942/early 1943. The DB 604 was producing better than 2000 PS in 1939.

Dr. Tank would have been thrilled to have Jumo 222A engines for the Fw-190 program. So would Dornier for the Do-217 bomber (which becomes a Do-317 with Jumo 222 engines). Heinkel would have done backflips if RLM had provided him with Jumo 222A engines for the He-177B heavy bomber and He-219 night fighter.

And then they would have started tearing their hair out once they got the engine installed and running on the aircraft. Even the early operations with the 801A/B or the Napier Sabre weren't as unreliable.

222 development started in 1937. By mid 1941 even the derated versions of the engine were still unacceptable in terms of reliability. A whole list of problems with the engine is given: fractures due to vibration, piston seizure, casing corrosion and bearing failures. These were related to poor quality materials in the engine (notably a lack of tin) and problems with the synthetic lubricants.

Put the 222A-1 into service in 1942 and you're probably going to get a repeat of the He-177's early service life, which was a debacle.

Demanding even more power from the Jumo 222 was just one of many strange RLM engine decisions.

The first demand for more power from the Jumo 222 was a result of the changing Bomber B program requirements, notably a higher take-off weight/bomb-load for the Ju-288. It was deemed necessary for the 'B' bombers to have 2500 hp per engine to help with take-off, thus the redesign to produce the 222A-2. Even with the redesign, the engine was still hampered by reliability problems and 2500 PS bench test wasn't passed until the end of 1942.

Remember that the initial Bomber B program specifications were written shortly before the outbreak of war. Combat experience meant that Germany wanted more from its next generation of bombers.

The 3000 hp requirement resulted in another redesign, but this didn't happen until (I think) 1944.

 

[Jabberwocky]

You mean DB603s?

If it had been fitted with DB610s I'm sure it woudln't have been underpowered.

Yes, DB 603s of course. You are correct.

610s were planned for the P.1055 aircraft, which was the older brother of the He-219 design.

 

[wuzak]

Comparison of the DB604 and the Jumo 222

DB604
Takeoff - 2660hp @ 3200rpm and 1.42ata
Max (emrgency I guess) - 2470 @ 3200rpm, 1.42ata, 20,600ft.
Climb and Combat - 2270hp @ 3000rpm, 1.30ata, SL
Climb and Combat - 2120hp @ 3000rpm, 1.30ata, 21,000ft
Max Cruise - 1830hp @ 2800rpm, 1.15ata, SL
Max Cruise - 1860hp @ 2800rpm, 1.15ata, 20,000ft.

Jumo 222A-1/B-1
Takeoff - 2500hp @ 3200rpm
Max (emrgency I guess) - 2200 @ 3200rpm, 16,400ft.
Climb and Combat - 2240hp @ 2900rpm, SL
Climb and Combat - 2060hp @ 2900rpm, 16,500ft
Max Cruise - 1900hp @ 2700rpm, SL
Max Cruise - 2700hp @ 2700rpm, 16,500ft.

Data from GED0109
GED0116

Anybody got better sources - particularly for the DB604?

 

[davebender]

By mid 1941 even the derated versions of the engine were still unacceptable in terms of reliability

Do you have data to support this statement?

Mid 1941 BMW801C engines produced 1,539hp with a service life of about 25 hours. I think even early model Jumo 222A engines could exceed that level of performance.

 

[Milosh]

Do you have data to support this statement?

Finally the Jumo 222 did not reach a real production status. Technical problems remained until the end of WWII. A total of 289 engines were built until the end of the war. The Jumo 222 was the standard engine of the Bomber B program of the RLM. Due to the intensive development problems of this engine, finally the complete Bomber B program came to an unsuccessfull end.

Junkers Engines - Jumo 222

Then there is Wiki.

 

[davebender]

That doesn't tell us anything as most aircraft engines have some technical problems.

 

[Shortround6]

The British built just over 300 Perigrine engines and that number managed to keep two squadrons of twin engined fighters in service for over two years. Nearly the same number of Jumo 222s kept zero number of combat aircraft in front line service for even few days.

High powered aircraft engines are very complicated beasts and the rapid progress of the 30's when engines gainied 50% in power in just a few years without a whole lot of trouble fooled a lot of people into thinking that that rate of progress would continue. While progress continued to be made it came at ever increasing costs in complication, engineering and test time. with so many of the German records lost or not easily available we are left looking at American and British programs to draw comparisons from. P&W took about 4 years to go from initial concept to first production engine of the R-2800. On the same day in 1940 they started on two replacement projects. The R-2800 "B" series ( a low risk, minor modification engine of around 150 more HP) and the R-2800 "C" series ( an engine that required new manufacturing and fabrication techniques and that would wind up powering the P-47M&N and others). At about the same in 1940 they started work on the 28 cylinder R-4360 which used the same ( in size anyway) cylinders as the R-2800. The initial R-2800 had used 5 to 7 test engines (including 1 nine cylinder test rig) before production was authorized to start. The R-4360 went through over 50 test engines and, IRMC, well over tens times the amount of money before it iwas OKed for production. While the "B" series R-2800 went into production in under two years it took almost 4 years to get the "C"series into production and close to 5 years to get the R-4360 into production. And basically, what was a R-4360? A pair of R-2000s stuck together with a 1/2in stroke job. Apparently it was all the little details that held things up.
P&W was one of the largest aircraft engine makers in the world in the late 1930s and ended WW II not only in a dominating position but not content to rest on it's laurels (like Wright) and was investing in the jet age with research and development.

 

[Siegfried]

What about putting people on the BMW 802 and axing the BMW 803.

BMW 803 came out of the Bramo (BRandenberg MOtor) works near Berlin, once Siemens and Halske (where the single throttle Kommandogeraet came from) while the 801 and likely the 802as Bravarian. IE different team. The Bramo team actually produced the 003 jet engine.

So you would need to split the team.

The 802 was a radically different engine to the BMW 801
1 More cylinders
2 Same bore but much longer stroked.
3 Valves placed in line for better cooling airflow
4 Varable valve timming for exahusts to allow tuned scavenging.

To have any chance to win or stablemate the war the Germans needed the BMW 802, DB604 or Jumo 222 engine by 1943 this is because
1 They could not afford a large bomber fleet with escorts.
2 fast aircraft like the Mosquite lack punch to inflict damage upon the enemy and can be countered by lightened fighters (except at night)
3 They needed a large bomber, driven to the same speed limits as fighters but with an armament and heavier bomb load

A Ju 88 with Jumo 222E/F engines (known as a Ju 388) was estimated to be capable of 440 mph for instance about 408 with the Jumo 222A/B

 

[davebender]

Nearly the same number of Jumo 222s kept zero number of combat aircraft in front line service for even few days.

60 Jumo 222A engines and 21 Ju-288 airframes were under construction during December 1941 when Milch pulled the plug on the program. Only two of the 21 Ju-288s were allowed to complete construction. It's almost as if Milch wanted to prevent the Ju-288 and Jumo 222 engine from proving itself in combat.

 

[Jabberwocky]

Do you have data to support this statement?

On Jumo 222 reliability?

Apart from the facts that the engine was never approved for serial production, the larger volume/lower RPM Series II engines were still plagued with ignition issues and that the bearing, piston and vibration issues weren't solved until another major redesign in late 1943 and the fact that even the slightly more reliable Series II engines were cancelled.

Then there is the fact that while the Ju-288 was originally scheduled to fly in October 1940 with Jumo 222s, it didn't actually make its maiden flight until June 1942, with BMW 801s, owing to the continuing problems with the 222.

 

[Siegfried]

On Jumo 222 reliability?

Apart from the facts that the engine was never approved for serial production, the larger volume/lower RPM Series II engines were still plagued with ignition issues and that the bearing, piston and vibration issues weren't solved until another major redesign in late 1943 and the fact that even the slightly more reliable Series II engines were cancelled.
QUOTE]

Piston engines took 6 years to develop and get into production, in this regard the Jumo 222 was doing quite well progress wise for an engine initiated in 38/39 for instance compare the CW R-3350 which first ran in 1937 but still gave interminable problems in 1943 and early 1944. I doubt the Jumo 222 would have been any more troublesome than the Napier Sabre.

The engines chief designer was Ferdinand Brandner, latter famous for managing the production program of the Jumo 004, working to effectively develop the NK-12 turboprop and latter developing an post war augmented turbojet known as the Brandner E-300 for what is essentially a Meserschmitt supersonic fighter (built abroad in first spain and then egypt but essentially designed in Germany)

But I digresss, perhaps therse was simply too much expectation of the Jumo 222, it could likely have entered production in 1943 in derated form. (about 2200). The bearing problems were solved but apparently required many strategic materials for the bushings. (the orbital mossion tends to squeeze out the oil from a bearing of a radial like engine)

The Germans were left with the Jumo 213A and DB603A from late 1942 which though good were not in the same class as the Jumo 222. These engines only really began to mature into 2000+ hp engines in late 1944 though they might have made 1900 with C3 fuel as the Jumo 213C and DB603G

 

[wuzak]

Piston engines took 6 years to develop and get into production, in this regard the Jumo 222 was doing quite well progress wise for an engine initiated in 38/39 for instance compare the CW R-3350 which first ran in 1937 but still gave interminable problems in 1943 and early 1944. I doubt the Jumo 222 would have been any more troublesome than the Napier Sabre.

I think the difference here is that the Sabre had difficulties in production (out of round sleeves, made, in part, on Victorian era machinery, with poor quality control) and maintenance. The Jumo 222, it would seem, had some serious design flaws that needed redesigning a couple of times to make them barely adequate. It is similar in that regard to the Rolls-Royce Vulture. In the case of the Vulture the, not unreasonable, decision was taken to stop development so they could concentrate on the Merlin and the new Griffon (other projects were dumped too). The situation of the war very much dictated the move.

But I digresss, perhaps therse was simply too much expectation of the Jumo 222, it could likely have entered production in 1943 in derated form. (about 2200).

The Vulture II had no end of trouble in the Manchester despite it being detuned. Why would we expect that not to be true of the Jumo 222 also?

The Vulture ran several times at 2500hp before its cancellation. And Rolls-Royce would have, no doubt, solved its issues before long - given the time and resources required (they did it with the Merlin). However, by 1941 Rolls-Royce had the luxury of neither.

Did Junkers have sufficient resources to concentrate on their production engines and continue to debug the 222?

The bearing problems were solved but apparently required many strategic materials for the bushings. (the orbital mossion tends to squeeze out the oil from a bearing of a radial like engine)

I don't think that the motion had much to do with the problem. More likely the loads. All cranks have essentially the same motion, the difference being how many loads that are being fed into them.

Radial engines had cranks, and I presume bearings, which were more highly loaded than a V12.

The Germans were left with the Jumo 213A and DB603A from late 1942 which though good were not in the same class as the Jumo 222. These engines only really began to mature into 2000+ hp engines in late 1944 though they might have made 1900 with C3 fuel as the Jumo 213C and DB603G

I stil wonder about why the DB604 was cancelled, and how close to being production ready it was.

 

[jim]

BMW801 did not recieve 2 stage 4 speed supercharger because it was very expensive
Fw 190c turbosupercharger did not enter production due to lack of materials to form heat resistant alloys
Jumo 222 could not solve its problems because no raw materials avalable
Jumo 004A(relatively reliable) was rejected because needed raw materials
DB 603 and Jumo 213 were denied use of C3 fuel (while 801 took priority despite the fact it was clearly of inferior potentional.) .
DB 605 had very limited acces to C3
Germans were expecting to construct high performance aero engines with what? Wood and steel? And using diesel fuel?
If no raw materials were available ,perhaps it would be a good idea not to cancel just Jumo 222 but the plans to risk a war as well
It appears to me that the only real failures of theengines industry was the (disastrous) DB 605 lubrications problems in 42/43 and the in time development of 2 stage superchargers.

 

[Shortround6]

There seems to have been an almost exponential rise in problems with the really big engines. Depending on wither you call the P&W R-4360 a radial (the only successful radial with more than 2 rows) or a multi-bank engine, nobody developed a successful multi-bank engine of over 3 banks. Nobody developed a successful radial with more than 9 cylinders per row ( Wright tried with a 22 cylinder engine using R-3350 cylinders for a 67liter engine). All of the successful 24 cylinder engines used two 12 cylinder crankshafts geared together. Given that there are practical limits on how big you can make each cylinder for a gasoline powered engine, they were bumping up against those limits and trying to get around them using mechanical complication. The only other solution was to use better fuel which allowed higher boost. With enough time and money perhaps the mechanical complications could have been solved (the P&W R-4360 even as much as it was used was NOT a trouble free or low maintenance engine) but really large engines turned out to be useful only when the alternative was multiple engines on what were already multi engine planes.

 

[Siegfried]

Ferdinand Brandner, the lead engineer, did write memoirs after the war. In the "Black Cross Ju 288/388/488" he is quoted as saying the engine was essentially developed to death due to 5 stroke and 3 bore changes designed to quickly achieve demands for increased power. The Jumo 222A/B series were essentially around 46 Litres (even they varied within that), the Jumo 222C/D was a radicall increase in swept volume to 55L designed to achieve power goals while the final Jumo 222A-3/B-3 and Jumo E/F returned to the orginal volume at the end of the war when the engine (which remained in development at a low priority) was back on the production program.

The Ju 288 had essentially started out as a 2 x 2000hp three seater designed to be 33% heavier but twice as powerfull as contemporary Ju 88 whereas after the BoB a 4th crew member, thickened fueselage added weight and required 2500hp immediatly.

These two web pages in German explain a fair bit, you could use google translate etc.

FlugzeugLorenz: Junkers Ju 288
http://www.flugzeug-lorenz.de/fileadmin/user_upload/PDF-Junkersbuch/Junkers_166-171.pdf

Otto Marder, who famously headed the Jumo engine development department noted that the Jumo 222 jumped a generation of technology not even proven in the Jumo 213; the specific power output of over 50hp/L was apparently quite challenging.

The second link notes the bearing problems caused by the orbital motion squeezing the oil out (I think of the big end bearings not the crank bearings)
It also mentions gas errosion (dampfgasblasen) and that it was solved.

The absence of the Jumo 222/BMW 802 and DB604 left a hole in the German engine development program compunded by the DB606/DB610 (coupled engines) failures being unable to provide a backup (at the cost of inferior range though at higher speed)

This left the Luftwaffe with 3 engines of about the same power: BMW 801D (C3) at 1700, DB603A at 1750 and Jumo 213A at 1770. (NB the BMW 801 was producing more with C3 einspritzung ie rich mixture injection: I believe 1850 to 1950 hp). The power levels began to rise in 1944 beyond 2100hp and were heading towards 2700hp.

In a way they did gamble correctly but I still think they could have managed the effort much better and had at least one hyper engine going by 43

 

[Gixxerman]

Great links Siegfried (even with the translate function).

I can't help noticing the mention of bearing failures and it keeps coming back, as far as I can see, to the central issues Germany had with so many projects during the war.
Limited resources, in this case in materials as well as fuels lubricants.

Germany undoubtedly had many brilliant engineers designers but between having to make choices of priority in production (where even very promising designs must be shelved or cancelled outright due to the disruption trying to introduce them to mass-production would inevitably bring) to the limitations of their raw materials situation it seems to me to be no surprise that their aviation history in WW2 has several 'what ifs'.
This seems to me to be perfectly natural and to be expected.

(and so too are the tales of stupidity/blindness/petty officialdom and all the other complaints those on the receiving end of decisions they did not like/agree with made.....although it also has to be said that the nazi state was especially affected by political in-fighting personalities clashing)

Nevertheless, despite all of the interesting and very impressive projects, the fact remains, a medium sized country just cannot hope to win a world war, given the allies she has verses those that ended up allied against her.
(as the 1st link mentions clearly)

I think that if Germany could have had the Jumo 222 in 1942 the outcome of the war, at least for Germany if not western Europe would have been little different.
It's much the same as with the idea of the Me262 a year or so earlier than it managed - Galland quite rightly said he thought, at best, it would only have led to western Europe in Russian hands.

The world suffers a longer war......and given the historical fact of the enormously increased scale of German losses in the final year of the war most probably a much worse situation for the German people Germany after
(and not let's not forget the additional time this would have given the nazi state to murder many more people from all over Europe the east in the death camps etc etc).

Their only hope for a true game-changer was the atomic bomb one way or another they came nowhere close to it.

Thank God.