Why no Jumo-222?

[delcyros]

After reading from the Jumo-222 compact 2000hp - 3500hp class engine, I wonder why it was not put into mass production. Only 240 specimen have been produced 1941 to 1945. The engine was more compact than the BMW-801, more powerful and about as heavy but didn´t required C-3 fuels.
I read that the Jumo-222 required to much rare ressources (but so did the BMW) or that it was abandoned for purely political reasons (Milch wanted to break the Junkers company).
The Ju-288 appearently showed the Jumo-222 beeing more reliable and economically efficient than the heavier and larger Db-610, so what was the case here? Any ideas?

 

[Juha]

Hello Delcyros
I don't have the answer, only the old info that the 222 project run into technical problems but you might find the answer from this publication TMV6N3

Juha

 

[red admiral]

The targets kept on moving, from 2000hp to 2500hp to 3000hp and as a result the design had to keep changing in order to keep pace. Freezing the design at 2000hp level, building a few thousand to iron out problems that would arise and then start going after more power would be a better option. Quite a similar problem to the RR Vulture. Initially problems, that were then solved, but production so low that it never went any further.

 

[davebender]

Apparently the 2,000 hp Jumo 222A engine passed a 100 hour test during 1941. Did reliability improve beyond that, or was the design shelved in favor of the larger and more powerful Jumo 222C?

I see some allegations of technical problems.
- Shortage of tin for the engine bearings.
- Poor quality of lubrication oil.
I have a difficult time believing either of these claims as they were not a problem for the 1,750 hp DB603 and Jumo 213 engines.

 

[delcyros]

Thanks for Your inputs, Dave, Juha and Red Admiral.

As far as I have seen, the Jumo-222A-1 was designed to run on 2500hp / 3200rpm /SL and was in it´s first production version derated to 2000hp at SL raising to 2200hp @ 16400ft. The take-off and emergancy rating was tested but showed bearing damage and piston seizure and thus was blocked. The two speed, single stage Jumo-222A-1 could deliver for 30 minutes the 2000hp/SL rating and was run in 1940 repeatedly on the testbench (flown on a Ju-52, too). When the requirements moved to larger capacity A-2/A-3 and then to the Jumo-222 C/D engines problems still were unsolved except for the basic Jumo-222A-1 design.
There was some increased interest late in the war to come back to the original A-1 design fitted with a new two stage, three speed supercharger ( Jumo-222E/F).

It is particularely important, esspeccially with reference to Red Admiral, that the initial Jumo-222A design at 2000hp (still running on B4-fuel) was choosen for mass production in 1941. The RLM even financed the installation of a special Junkers aeroengine works at Wien-Neustadt (FMO-Flugmotorenwerke Ost) to deliver monthly 1000 engines of this 2000hp class Jumo-222A-1 design. On 25th of july 1941 11.500 construction workers begun building six production halls. On 28th of oct. the halls were worked enough that Junkers ordered tooling equipment beeing produced for this plant.
At about this time, as K. v. Gersdorff pointed out, several long time issues were discovered on the Jumo-222A, he mentions vibration fractures and casing corrosion which demanded engine changeovers on the Ju-228V-prototypes equipped with the Jumo-222A after 20 to 50 hours flighttime.
That´s about as poor as the engine changeover times for the contemporary BMW-801C, actually it´s even a bit better. However, he makes a point that increased demands on the Ju-288 lead to increased demands on the Jumo-222A to clear take off emergancy raring, which in turn run into the aforementioned problems and required extensive redesign, esspeccially in the enlargement of the bore and a change in the ignition system to lead into the Jumo-222A-2/A-3 designs.
Trial production of the Jumo-222A commenced in Taucha and at other plants.
The RLM canceled serial production of the Jumo-222A in december and handed over the FMO-plant to Daimler Benz for db-610 production, something which never materialised (only about 50 specimen were produced before production was halted there). All tooling equipment already installed there was put into store. L. Budraß dissertation makes a strong case for Milch intentionally wanting to stall the Ju-288 program which he feared could become to important for the german aerial procurement program and would lead to a much to important role of the Junkers company. The Ju-288, however, would only realise with the Jumo-222.

Production numbers are inconsistent, going as low as 240 and as high as 289.

 

[davebender]

Even the 2,000 hp version compares well to the BMW801 radial. It appears that Germany had a chance to build a something similiar to the Fw-190 D9 during 1942. Only with 14% more HP. Alternately the large Jumo 222 engine could be reserved for bombers like the Do-217 and Me-410. This would free up DB603 engines for use in Fw-190 fighter aircraft.

 

[Colin1]

It didn't seem to cut it during testing
By the time it finally began to realise its potential in the 222E and F, its factories in Dessau were being bombed to the point where uninterrupted production was practically impossible.

The Germans ended up with nothing to show for roughly 5 years of development. Around 300 units were manufactured, none of which saw operational service. Indirectly, it also damaged powerplant design in other areas of the industry as projects were waived in favour of the 222. It was a costly failure whichever way it was looked at.

I believe Junkers kept going with the 222 after the RLM had given up on it in 1942.

It is possible that along with the RLM's exasperation over the 222's problems was the general abandonment at about this time of big, powerful, piston-engined projects across the industry in favour of jet programs. If you recall, this was the eventual fate suffered by the BMW 801's successor, the 802.

 

[delcyros]

Some Ju-288 prototypes (both, Db-610 and Jumo-222 driven A/C) saw operational use as recon aircraft over Russia, so it´s not necessarely right to say the Jumo-222 didn´t saw service.
The RLM also never gave up on the Jumo-222. From december 1941 to late 1942 the Jumo-222 was given a lower priority and afterwards again a higher priority when the db-606 and db-610 both run into very serious cooling issues.
The lower priority in 1942 stalled the whole bomber-B prgram.
Plants and tooling was already set up. I tend to believe that the suicide of E. Udet was a critical component in this matter. Under his supervision Junkers had a special position in the german procurement program, which was indicated by the company development of airframe aeroengines. No other company had such a situation.
This cancellation appears not to be caused by technical problems with the Jumo-222A but rather by the political will demonstrated by Milch to break Junkers special position.
"Die Absetzung der Jumo-222 wurde nicht nach dem Stand der Technik erwogen"
Rather contrary, Milch knew that Ju-288 Jumo-222 were designed in conjecture and he used the priority degration of the engine to stall the entire program. At the meantime, he took away Junkers responsibility for FMO aeroworks with the explenation that no airframe was anymore aviable for the Jumo-222. This appears to be an argumantation in circle.

However, when factoring in the possible impact of a Ju-288 mass production, it might seem to have some importance. The Ju-288 was head shoulder abover He-219, Do-317, Fw-191, Me-210 and Ar-240. The manufacturer Arado, Focke Wulf, Heinkel, Messerschmidt and Dornier would only be active with license production of Junkers bomber aircrafts. Only Messerschmidt Focke Wulf would keep an independent position with their own fighter designs.

 

[johnbr]

Here are a photo of the Ju-222 and DB-604

 

[delcyros]

Even the 2,000 hp version compares well to the BMW801 radial. It appears that Germany had a chance to build a something similiar to the Fw-190 D9 during 1942. Only with 14% more HP. Alternately the large Jumo 222 engine could be reserved for bombers like the Do-217 and Me-410. This would free up DB603 engines for use in Fw-190 fighter aircraft.

I was surprised to see the Jumo-222A-1 fitting into the Fw-190V1 cowling. It´s a tad bit heavier than the BMW-139, esspeccially when considering the liquid cooling unaccounted for in dry weights but it has less frontal area and is about the weight of a BMW-801. Altough it could fit into a Fw-190 the Jumo-222 is probably better used up in bomber designs such as the >400 mp/h Ju-288.

 

[davebender]

Jumo-222 is probably better used up in bomber designs such as the >400 mp/h Ju-288.

Put the 2,000 hp Jumo 222 in the Ju-88G. Your night fighter aircraft will have better performance. And you free up BMW801 engines for additional Fw-190s.

 

[delcyros]

Certainly the Ju-288 would be better in all roles. It also could be produced by virtue of modular construction techniques in rapidly increasing numbers for less productive effort.

 

[davebender]

Certainly the Ju-288 would be better in all roles. It also could be produced by virtue of modular construction techniques in rapidly increasing numbers for less productive effort.

Then why did Germany chose to produce the Ju-88G and Ju-88S during 1944 rather then variants of the Ju-288?

 

[delcyros]

During 1944, the Ju-388 -basically a simplified Ju-288- was just entering mass production, when priority shifted back to fighter planes and finally to jet planes. In 1942, when the Ju-288 could have entered mass production, the engine problem stalled the problem. The only other engine powerful enough to be considered were the Db-610 (which soon encountered it´s own developmental issues) and the BMW-801, which was urgently required for Focke Wulf 190 programs and unfortunately was very sensitive to high grade fuels. Such excessive C3 fuel consumption would be prohibitive.
The Db-603 and/or Jumo-213 would have been possible but the former was reserved for Me-210/410/He-219 and the latter just entering project stage in development.
Late in ww2 the Jumo-222E/F should again become a major aeroengine with mass production just beeing in preparation when the RLM stopped piston aeroengines in favour of jet engines. The Ju-388J2 serial night fighter with Jumo-222E/F (-prototype at advanced stage of production when RLM cancelled this program in favour of jet programs) would be pretty fast, 685 Km/h with full equipment, including the rather bulky SN-2 device (710 km/h without SN-2) and a range of 2570 km.

 

[davebender]

Hmmm. The entire Ju-88/Ju-188/Ju-288/Ju-388 program is a mass of confusion to me. The follow-on aircraft used components from the original Ju-88. However components from the Ju-188 made their way onto newer versions of the Ju-88, which continued in production to the end of the war.

 

[delcyros]

The whole Ju-288 program was the single most expansive with regard to funding of R&D. Over 80 patents were granted to Junkers as a consequence. So from Junkers perspective, it made sense to incorporate as much as possible in the Ju-188 / 388 as well as into older -88 production. The cancellation of the Ju-288 itselve is what makes headaches. It came after Junkers installed the tooling and production lines for it´s engines at FMO / Vienne and airframes at Bernburg / Dessau. Some 60 Jumo-222A engines and were at different stages of construction when the RLM ordered the FMO to stop the Jumo-aeroengines in late 1941 and more than 21 Ju-288 airframes were under construction when the RLM ordered all work to be scrapped in 1942. All planes except for two further prototypes were scrapped on the assembly lines. The explenations are not technically but politically.

 

[davebender]

http://www.econ.yale.edu/growth_pdf/cdp905.pdf
Have you seen this paper on the Ju-88 program? Unfortunately it does not cover the Ju-188, Ju-288 and Ju-388.

 

[davebender]

Found this on the web.
engine | piston-engine development | air-cooled radial | 1945 | 2394 | Flight Archive

The 213J was the latest mark scheduled for production. The weight with intercooler was 2,325 lb.,
and the power 2,350 h.p. for take-off on 87-octane fuel at 3,700 r.p.m. They seemed hopeful of
quickly obtaining a production rating of 2,600 h.p. from the 213, and appeared willing to accept an
abnormally high piston speed and high r.p.m.

How close was the Jumo 213J to mass production? With 2,350 to 2,600 hp it makes the Jumo 222 engine unnecessary.

If the Jumo 213 engine had this much potential why wasn't it developed sooner? It appears to me that the Jumo 213 engine is simply a highly evolved Jumo 211 engine.

 

[Propellorhead]

Hello Delcyros
I don't have the answer, only the old info that the 222 project run into technical problems but you might find the answer from this publication TMV6N3

Juha

As I understand it the Jumo 222 was in fact six engine blocks arranged around one common crankshaft and this lead to huge plumbing problems. In particular an inability to develop a successful supercharger for high altitude work.

With the A model poor octane ratings of the fuel obliged the engine to run at high revolutions to deliver the required horsepower. This in turn led to cooling problems and desintegration of bearings, low time between overhauls, etc. These were the technical issues. No real solution was ever found to supercharge the engine thus it was of little use for a high altitude fighter or bomber.

 

[davebender]

Ju-288 program was the single most expansive with regard to funding of R&D

I like the Ju-288 and Jumo222 engine. However I am coming around to the conclusion the entire Bomber B program was a huge strategic mistake. Pour that same development money into the simpler DB603 and Jumo 213 V12 engines and they could be in mass production (say 1,000 engines per month) before 1942.

That provides Germany with Do-217 bombers (DB603 engines) escorted by Fw-190D9 fighters (Jumo213 engines). A formidable strike force during 1942 and still very capable by 1945 standards.