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

[Shortround6]

The P-47D-5 with water was generating 2300 hp in 1943. In the end, it was generating 2800 hp (61hp/ltr)

To be fair the 2300hp was with 100/130 fuel which allows a cylinder pressure roughly 80% higher than 87 octane. 87 octane has a performance number of 68.29 so even 100 octane allows about a 45% increase in pressure. Going to 130 PN means another 30% increase so depending on wither you add or multiply??? either way a big increase and even if different engines respond differently to the same fuel there is still going to be a big difference. using water means that teh R-2800 was using the same thing as MW-50 on top of the 100/130 fuel.



In the end the the R-2800 that gave 2800hp in the M&N Thunderbolts was an entirely new engine that, while interchangeable in installations actually shared NO parts at all with ANY previous R-2800 except for perhaps the starter dog. it may have required both 150 PN or 115/145Pn fuel and water injection to reach the 2800hp. It also used a bigger/higher performance turbo than previous P-47s.
Military power without water and WER settings was 2100hp.

[Siegfried]

To be fair the 2300hp was with 100/130 fuel which allows a cylinder pressure roughly 80% higher than 87 octane. 87 octane has a performance number of 68.29 so even 100 octane allows about a 45% increase in pressure. Going to 130 PN means another 30% increase so depending on wither you add or multiply??? either way a big increase and even if different engines respond differently to the same fuel there is still going to be a big difference. using water means that teh R-2800 was using the same thing as MW-50 on top of the 100/130 fuel.

In the end the the R-2800 that gave 2800hp in the M&N Thunderbolts was an entirely new engine that, while interchangeable in installations actually shared NO parts at all with ANY previous R-2800 except for perhaps the starter dog. it may have required both 150 PN or 115/145Pn fuel and water injection to reach the 2800hp. It also used a bigger/higher performance turbo than previous P-47s.
Military power without water and WER settings was 2100hp.

Good information; where did you get the PN numbers for octane ratings below 100?

The BMW 801F, delayed by tooling issues, was to produce 2600hp in service (presumably on C3 + MW50) this is comparable to the R-2800 and respectable considering that the 801 was an "R-2600"

[davebender]

If RLM held BMW to the same standards as Junkers the 1941 BMW 801 engine would have been required to produce almost this much power while running on B4 fuel and with an operational service life better then 50 hours.

[Siegfried]

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.

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?

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.

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

I don't think the vulture was a bad engine: too much of it was demanded of it too quickly as a result of Manchesters uncontrolled wieght growth, it peformed reliably in the Tornado and its problems (it needed enlarged big end bearings) to handle the sustained high power levels of bomber climb out. Vulture was a good engine that was dropped because Merlin and Griffon was an altermative. The Sabre was not that important nor was a Vulture altermantive while Lancaster was not better than Manchester in terms of speed. It was dropped for economic reasons.

However the Jumo 222 Ju 288 combo was a monster.

I can't see any insupperable problems with the Jumo 222; the 6 cyclinder radial is a stable balanced arrangment. Stacking 4 behined each other adds only torsional vibration issues in the long (but not too long) shaft. There are no silly sleeve valves that need special machining, alloys etc. The issues of the Jumo 222 came from high stresses and specific power levels.

Lutz Budrass puts the death of the Jumo 222 due to a RLM (Milch) strategy to breakdown the Junkers concerns by splitting the airframe and engine division. Milch consistantly showed a preferance for high production volumes.

What actually at up development capabillity was the Jumo 004 turbojet

[Siegfried]

50hp/l - I suppose that is challenging.

I mean the Merlin didn't get to 50hp/l (1350hp) until...1940. By the end of teh war the Merlin was just about continuouslyrated at 50hp/l.
The Griffon struggled to get 50hp/l - actually, no it didn't. It entered service rated about 50hp/l.
The R-2800 got there in the end (2300hp).
The Vulture wasn't short of the mark (2100hp for 50hp/l) in the Mk V version.
The Sabre started life at about 54hp/l (on 87 octane fuel)- and went up.

The 50hp/L figure is only a relative bench mark: what matters is power to weigh ratio and of course ask you acknowlege it is on 87 octane.

The Jumo high RPM is not extraordinary: A higher power engine will be stressed either by high boost or high RPM. Piston velocity is a better figure of merrit in anycase.

[Shortround6]

Good information; where did you get the PN numbers for octane ratings below 100?

From a book called " Aviation Fuels and their effect on aircraft performance" prepared by the Ethyl Corporation For the USAAF and US Navy. I believe to was prepared with the help of Sam Heron

[wuzak]

I don't think the vulture was a bad engine: too much of it was demanded of it too quickly as a result of Manchesters uncontrolled wieght growth, it peformed reliably in the Tornado and its problems (it needed enlarged big end bearings) to handle the sustained high power levels of bomber climb out. Vulture was a good engine that was dropped because Merlin and Griffon was an altermative. The Sabre was not that important nor was a Vulture altermantive while Lancaster was not better than Manchester in terms of speed. It was dropped for economic reasons.

The Vulture big end bearing problems were largely a result of poor connecting rod design - and con rod bolt failures. The two pieces could move relative to each other, and thus caused the bearing to fail.

A similar situation occured with the main bearings, with tehtwo crancase halves moving relative to each other. This was solved with dowel pins to prevent the motion.

[wuzak]

I don't think the vulture was a bad engine: too much of it was demanded of it too quickly as a result of Manchesters uncontrolled wieght growth, it peformed reliably in the Tornado and its problems (it needed enlarged big end bearings) to handle the sustained high power levels of bomber climb out. Vulture was a good engine that was dropped because Merlin and Griffon was an altermative. The Sabre was not that important nor was a Vulture altermantive while Lancaster was not better than Manchester in terms of speed. It was dropped for economic reasons.

The Vulture big end bearing problems were largely a result of poor connecting rod design - and con rod bolt failures. The two pieces could move relative to each other, and thus caused the bearing to fail.

A similar situation occured with the main bearings, with tehtwo crancase halves moving relative to each other. This was solved with dowel pins to prevent the motion.

[davparlr]

To be fair the 2300hp was with 100/130 fuel which allows a cylinder pressure roughly 80% higher than 87 octane. 87 octane has a performance number of 68.29 so even 100 octane allows about a 45% increase in pressure. Going to 130 PN means another 30% increase so depending on wither you add or multiply??? either way a big increase and even if different engines respond differently to the same fuel there is still going to be a big difference. using water means that teh R-2800 was using the same thing as MW-50 on top of the 100/130 fuel.

In the end the the R-2800 that gave 2800hp in the M&N Thunderbolts was an entirely new engine that, while interchangeable in installations actually shared NO parts at all with ANY previous R-2800 except for perhaps the starter dog. it may have required both 150 PN or 115/145Pn fuel and water injection to reach the 2800hp. It also used a bigger/higher performance turbo than previous P-47s.
Military power without water and WER settings was 2100hp.

Isn't that like saying the P-51H is not a real P-51? In both cases, the lineage is certainly there. What dash number did the "C" engine start? The dash 59 on the P-47D-27 generated 2600 hp.

[davebender]

U.S. Strategic Bombing Survey Aircraft Division Industry Report
With a planned production of 500 Jumo 222s per month Ostmark would have been the second largest German aircraft engine factory (Genshagen DB605 factory was largest).

Why would someone interested in high production volumes derail Jumo 222 engine production?

[Shortround6]

Isn't that like saying the P-51H is not a real P-51? In both cases, the lineage is certainly there. What dash number did the "C" engine start? The dash 59 on the P-47D-27 generated 2600 hp.

The dash numbers overlap. For example the Army Air Force -57 is a "C" series engine but the -59 and -63 are "B" series engines. The Army and Navy dash numbers are completely out of whack, Navy "C" series engines can be as low as -14 while the last dash number for an Army "A" series engine is -39.

As far as the P-51H not being a real P-51?? the lineage is there but you can't make a P-51H airframe out of P-51D parts can you? A bit like the old 351 Ford V-8s. Saying you can get a certain power level out of a 351 Cleveland doesn't mean you can get that power level out of a 351 Windsor even though they are both small block Fords with the same bore and stroke

The "C" series R-2800 used steel cylinder liners in an aluminium "muff" that had the cooling fins instead of an all steel cylinder with machined in fins. The Cylinder head was forged instead of cast to allow for more/deeper fins. Both aided cooling for the higher powers desired. A new crankshaft and crankcase allowed for more power and higher rpm. New pistons and connecting rods and so on. While a certain "B" engine went to well over 3000hp on the test stand at the factory (using phenomenal amounts of boost and water injection) and survived P&W felt the "C" series was needed to get the power at the reliability and durability levels they wanted.
How much was needed just to get extra power and how much was needed to get more reliability and longer life at the same or higher powers I don't know. The postwar "CB" series was good for 2300hp take-off without water injection in airline service. That is something to be remembered about some of these WER ratings, especially the ones using early water injection or MW/50. Every single use had to be noted in the engine log books and extra maintenance procedures were supposed to be followed. Each use sometimes took hours off the engine life to scheduled overhaul and also required more frequent spark plug changes or inspection.

[Milosh]

U.S. Strategic Bombing Survey Aircraft Division Industry Report
With a planned production of 500 Jumo 222s per month Ostmark would have been the second largest German aircraft engine factory (Genshagen DB605 factory was largest).

Why would someone interested in high production volumes derail Jumo 222 engine production?

Because that meant more of the other engines could be built.

[Siegfried]

U.S. Strategic Bombing Survey Aircraft Division Industry Report
With a planned production of 500 Jumo 222s per month Ostmark would have been the second largest German aircraft engine factory (Genshagen DB605 factory was largest).

Why would someone interested in high production volumes derail Jumo 222 engine production?

It's hard to tell. Perhaps he had seen too many high tech disasters (Me 410 and He 177) and just wanted dependable mass production. In my view these programs were simply mismanaged: the He 177 could have been built as propossed as a 4 engined version while the Me 210 could have been better risk managed. Milch thought that German could wind the war only if the Me 262 got into mass production in 1943. Perhaps he was an egoist, or was it politics. He was rather taken aback wehn his nominal subordinate Kammhuber (head of the night fighter force) bypassed him and got the He 219 into production (instead of his pet project the Ta 154)

The Ju 288 itself was to be a masterpiece of production engineering. The 4 wing spars were pressed out in one opperation by a 30,000 ton press and so were perfectly tapered and shaped for optimal strength and each point even the attachment bolts were produced in the press and only received final threading and machining. This made the spars faster and cheaper to produce. The entire fueselage and wings were built to high tollerances of smoothness. The pressurised crew cabin could be detached by exposlive bolt to rescue the crew. Wing skins could be removed to service damaged fuel cells. This is the kind of technology one would see in an F-111.

The Jumo 222 would have been built for mass production in a similar way.

The idea was that the Ju 288 was cheap and fast to produce.

[davebender]

How do you figure that?

Ostmark was built to produce Jumo 222A engines. You cannot change tooling and retrain workers for Daimler-Benz production simply by signing an order. You will lose an entire year of production (about 6,000 Jumo 222A engines) during the conversion process.

[davebender]

Then why didn't he make it happen? The Me-262 airframe was ready (or ready enough). So was the Jumo 004A engine.