Jumo 222: what's the truth?

[Shortround6]

No.

Two things:
1. British could use/plan on better fuels to increase power more than the Germans could.
2. The British were not so wedded to the twin engine concept. If more than 4000hp was needed they shifted to four 1200-1600hp engines rather than try for 2500+ engines.

 

[wiking85]

Out of curiosity why didn't the Lancaster ever use the Sabre?

 

[tomo pauk]

Dry weight of the Sabre was almost 1000 lbs greater than of the Merlin 21. Add heavier cooling lubrication system, bigger prop cowling and the powerplant group goes up for 6000 lbs, or more? That added weight cuts in fuel and/or bomb load. Plus, the CoG need to be addressed, since all of the extra weight is in the front of the CoG. The counterbalance means new weight added to the aircraft. Some reinforcements will need to be added to the airframe - further 1000 lbs? Before you know it, it's 8000 lbs added to the Lanc - that would lug only 1/2 of the bomb load, or have much reduced radius.

 

[davebender]

Probably weren't enough Sabre engines available when the Lancaster bomber entered mass production.

Do we have production data for the Sabre engine?

 

[Shortround6]

Lancaster was a 4 engine Manchester, When The Vulture was having troubles the Sabre really wasn't a working proposition either. The Sabre passed it's 100 hour test at 2000hp rating in June of 1940 but the production engines were still a mess and stayed a mess for quite some time.
There were projects for both a Sabre powered Manchester and a Centaurus powered version both both projects were dropped with the flight testing of the first Lancaster's.

 

[Piper106]

Back to our regularly scheduled program... the Jumo 222.

I think that that oh so German drive for perfection bit them big time.

The Jumo 222 was (or would have been) a technically masterpiece. On the other hand, brute force and ignorance in the form of a doubled Jumo 211 engine in a vertical H formation i.e. two vertical cyliner flat 12s running on two standard Jumo 211 crankshafts geared to one propeller shaft would have been much more likely to have yielded a a useful result.

For example, doubling the 1938 vintage 211B engine running at 2400 rpm would give 2400 PS / HP. Wikipedia gives the weight of an early 211 as 585 kg, doubled would be 1170 kilos (2580 pounds), compared 1088 kgs (2400 pounds) for 46.5L Jumo 222A. Plus with 70L available, development/growth of the H-24 Jumo could have followed in the foot steps of the Jumo 211 V-12, so there could have been 2600 PS / HP in 1940, and 3000 HP by 1943.

The H-24 version could have used the crankshaft, rods, pistons, cylinder liners, and cylinders heads of the 211. About the only totally new parts needed would be the crankcase casting, and the propeller reduction gear. As the Luftwaffe outgrew 211 V-12 powered aircraft, parts production and factories could have been converted into the H-24 version for the Bomber B program.

If you need to visualize, Google or Bing on "Arsenal H-24 engine". This was liberated France doubling of the Jumo 213 for post war.

 

[wiking85]

Back to our regularly scheduled program... the Jumo 222.

I think that that oh so German drive for perfection bit them big time.

The Jumo 222 was (or would have been) a technically masterpiece. On the other hand, brute force and ignorance in the form of a doubled Jumo 211 engine in a vertical H formation i.e. two vertical cyliner flat 12s running on two standard Jumo 211 crankshafts geared to one propeller shaft would have been much more likely to have yielded a a useful result.

For example, doubling the 1938 vintage 211B engine running at 2400 rpm would give 2400 PS / HP. Wikipedia gives the weight of an early 211 as 585 kg, doubled would be 1170 kilos (2580 pounds), compared 1088 kgs (2400 pounds) for 46.5L Jumo 222A. Plus with 70L available, development/growth of the H-24 Jumo could have followed in the foot steps of the Jumo 211 V-12, so there could have been 2600 PS / HP in 1940, and 3000 HP by 1943.

The H-24 version could have used the crankshaft, rods, pistons, cylinder liners, and cylinders heads of the 211. About the only totally new parts needed would be the crankcase casting, and the propeller reduction gear. As the Luftwaffe outgrew 211 V-12 powered aircraft, parts production and factories could have been converted into the H-24 version for the Bomber B program.

If you need to visualize, Google or Bing on "Arsenal H-24 engine". This was liberated France doubling of the Jumo 213 for post war.

How would this have been different than the DB606/10?

And what makes you think that the Jumo 222 would have been technical masterpiece?

 

[Piper106]

How would this have been different than the DB606/10?

And what makes you think that the Jumo 222 would have been technical masterpiece?

The "technical masterpiece" was a bit 'tongue in cheek', or 'graveyard humor'. However had it worked I'm sure there would be plenty of posters on this board (and other boards) holding it up as proof of German technical superiority over inferior British / American iron mongers.

Some advantages of a Jumo H-24 over the Daimler Benz DB 606 / 610 engines. First, there have been several threads about how Daimler Benz lacked production capacity, while there was 'plenty' of production capacity for the Jumo 211. A two crankshaft, 24 piston, 24 connecting rod engine eats up production capacity fast. Second, the DB 606 double engine weighed 1515 kg (3333 pounds), the DB 610 1540 kg. Considering that the Allison 24 cylinder V-3420 weighed within a few pounds of twice what their V-12 weighed, I feel my estimate of 1170 kgs (i.e double that of a Jumo 211 V-12) for a Jumo H-24 is reasonable. A 300 kg plus weight saving per engine is significant. The Damlier double engines also had a red hot exhaust collector at the very bottom of the engine cowling between the two vees, just waiting to start a fire should there be the slightest leakage of fuel or oil. On the proposed Jumo vertical H, the hot exhausts are on the outside of the cylinder banks, above the cowling bottom.

 

[Shortround6]

Unfortunately for a number of nations some of the engine designers of the 30's tended to get carried away with their own cleverness. Granted they were up against some real limits at times. You can only make cylinders so big for one. For a given type of fuel you can only use so much boost. This leaves you with lots of cylinders and/or high rpm as the only answers until the fuel guys hit the next level. Since small cylinders offer a number of advantages 1, better cooling due to higher cylinder wall to volume ratio. 2, better volumetric efficiency. 3, higher rpm due to shorter stroke ( less strain on parts) AND less time needed for flame front to cross smaller cylinder. It also seemed like the high cylinder count, high rpm engine offered real chances for big improvements.
Unfortunately adding cylinders and or spinning the crank faster was NOT as easy as it seemed. That and a few designers seemed to go out of their way to complicate things. The Jumo 222 was utter simplicity compared to the Wright Tornado. The ONLY good thing you can say about the Tornado is that they didn't build almost 300 of them

A few of our too clever for their own good designers also tried to make these high cylinder count engines as compact as possible. Granted they were looking for that big jump that would carry their company for years and years instead of a short term fix. While engine and materials men had learned an awful lot in the 30 something years since the start of powered flight there was still an awful lot more to learn and these complicated engines brought that home with a vengeance. Metal fatigue was just starting to be sorted out. They were just starting to get a good handle on vibration problems (of all sorts). Most (all?) companies didn't have airflow benches that could measure the air flow through cylinder head ports. Intake manifolds and airflow through them was more art than science. Even coolant flow entailed a lot of trial and error.

R-R used a system of run it until it breaks, fix it , then run it some more. The more cylinders you use the more stuff that can break and the more ways it can break.

Classic story on the Griffon is that they reversed the crankshaft rotation and ground the cams and rigged the ignition to suit and promptly broke two crankshafts in less than ten hours each. Somebody noticed that they were using the same layout for the crankshaft as the Merlin (the crank pins were staggered the same amount from front to back and in the same order) They made a "mirror" image crankshaft, dropped it in and ran with no problem. Not all vibration is the engine trying to bounce up and down or side to side. Harmonic vibration can do strange things, breaking parts that vibrate in harmony with the part/s causing the vibrations but located at some distance from the part/s causing the vibration. DO you try to damp the vibration to begin with or beef up the broken part/s ( which just may change the frequency at which they vibrate).

And most of these all too cleaver engines would have been an absolute BI*CH to service in the field.

 

[Elmas]

"None of the studs, nuts and bolt were accessible- you couldn't even see them!-You were feeling around corners and you'd got weirdly contorted spanners to get at them, giving it half a turn then chosing another spanner and giving it another bit of turn! oh, that was shocking!

Peter Jago, RAF engineer, about the Napier Sabre engine

 

[stona]

Many engines were difficult to service in the field. Goering wasn't too thrilled about the installation on the He 177, which he had inspected at Rechlin in May 1942.

"How is such an engine to be serviced on the airfields? I believe I am right in saying that you cannot even take out the spark plugs without pulling the whole engine apart."

From a transcript of a Goering Conference held on 13th September 1942.

So bad were the problems of maintenance that a special field maintenance unit (Feldwerft Abteilung zbV 1) was set up to support the first operational He 177 unit, II./KG 40.

Cheers

Steve

 

[cherry blossom]

A very interesting but biased account of Jumo 222 development is in Ferdinand Brandner's autobiography http://www.amazon.de/dp/3853391257/?tag=dcglabs-20. I haven't read it and most reviews focus on his later work but there is some mention of the effects of material shortages causing problems. The central problem that we are trying to understand is that the initial Jumo 222 model passed its 100 hours type test in April 1941 but despite that development seemed to go backwards. Could it be that the early prototypes used bearings made with alloys that could not be manufactured in quantity because of shortages of metals such as tin? Naturally changing the capacity twice may also not have speeded up the development of a reliable engine. Brandner is quoted as saying that the Jumo 222 was developed to death.

 

[Shortround6]

I think entirely too much is being made of the the type test.
The Napier Sabre passed a type test in 1940. hand built engine passed, production engines turned out to be another story. The Vulture passed a type test or it wouldn't have been put in the Manchester. The Centaurus was supposed to have been type tested in 1938? Or the Hercules. Wright R-3350 was type tested When? (first version, major redesign for the version that powered the B-29) Continental IV-1430 passed a type test in 1940, test flown in two types of aircraft several years later it was a dismal failure to be kind.

Germans were flying Fw 190s in combat with some rather less than reliable BMW 801 engines and yet the Jumo 222 got only limited flight time in a few prototypes despite all those engines being built?

 

[delcyros]

just get Prof. Lutz Budraß book and please stop speculating without sources.

 

[wiking85]

just get Prof. Lutz Budraß book and please stop speculating without sources.

AFAIK Budrass states that the engine was killed by Milch in an administrative act rather than technical issues; is that true as far as you know?

 

[delcyros]

Short answer: yes. It was Milchs intent to make sure that the Jumo222 fails in order to crush the special position of the Junkers company in the german military industrial aeronautic complex. Had the Ju288 succeeded it would relegate Heinkel, Dornier, Henschel and other manifacturers to the status of licensees from which they wouldn't recover. Everybody knew this.
Milch succeeded because he upped the performance requirements faster than Junkers MW could improve the output of the Jumo222.
When it eventually was about to reach the requirement of 1943 he ordered that airframe and engine should not be developed together and effectively killed both projects.
It was important that this engine fails, independent of application

 

[wiking85]

Short answer: yes. It was Milchs intent to make sure that the Jumo222 fails in order to crush the special position of the Junkers company in the german military industrial aeronautic complex. Had the Ju288 succeeded it would relegate Heinkel, Dornier, Henschel and other manifacturers to the status of licensees from which they wouldn't recover. Everybody knew this.
Milch succeeded because he upped the performance requirements faster than Junkers MW could improve the output of the Jumo222.
When it eventually was about to reach the requirement of 1943 he ordered that airframe and engine should not be developed together and effectively killed both projects.
It was important that this engine fails, independent of application

So in your opinion could the engine have succeeded in giving 2000HP by 1942 if it had not been 'developed to death' by Milch?

 

[davebender]

That's impossible to avoid if you want high performance. Hence the reason modern military aircraft and armored vehicles are designed for rapid replacement of the entire engine, which is then shipped back to depot for repair. This practice has it's roots in WWII.

 

[Milosh]

So dave the engines of the He177 were removed from the a/c and sent to a repair depot to replace the spark plugs?

 

[Shortround6]

ROFLMAO:

Not picking on the Jumo 222 here but even the P&W R-4360 had problems, it was made "reliable" but was a maintenance hog. If the starting procedure was not strictly adhered to it was possible to flood the engine and foul the plugs ( actually a common occurrence with WW II engines, or at least not uncommon) requiring that all 56 spark plugs be pulled, cleaned or replaced and re-installed before attempting to start the engine again. They don't send engines back to the shop in western country's for spark plug replacement or valve adjustment or other minor problems (leaking pipes/hoses etc. )