# DB 603 vs Ju 213



## silence (Nov 20, 2012)

I understand that Kurt Tank favored the 603 over the 213, being of the opinion that it was a better high-altitude engine. Why is this? What made it better for high-altitude use? Also, is there any special reason why they had their supercharger intakes on opposite sides, and could they have been reversed easily?


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## tomo pauk (Nov 20, 2012)

I'm not sure that Dr. Tank was favoring the DB on the grounds that it was a better high altitude machine, but at the grounds that 603 was available about one year earlier.
The supercharger intake position was a non-issue, the airframe producer can easily produce the part(s) needed for the cowling of any of those two.
As for what one was better - prior 1944 there is no match, since only the 603A is available. Once the 213A is available, it's higher RPM can counter the greater displacement of the 603, so the output was roughly equal above 6 km.


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## spicmart (Nov 21, 2012)

The exhaust tubes of the Jumo 213E were to produce more thrust than those of the DB 603L, which had 74 kW more power than the Jumo,
so much that the 213 E was considered to have superior propulsion performance to the 603 L.


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## tomo pauk (Nov 21, 2012)

Care to elaborate the part about the Jumo 213E producing more thrust than 603L?


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## rinkol (Nov 21, 2012)

Tank's thinking may have been motivated by several factors:

- 4 valves per cylinder (1 more than Jumo 213)
- variable speed supercharger drive (though later versions of the 213 benefited from a three speed supercharger drive)
- presumed early availability of DB 603 versions having improved high altitude performance (DB603E and G) 

In practice, the early DB603s had unacceptable reliability for single engined aircraft and the high altitude versions only became available at the end of the war or not at all. It may be that, of the versions having two stage superchargers, the Jumo 213E was available earlier than the DB 603L, though neither was available much before the end of the war.


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## tomo pauk (Nov 21, 2012)

The inital batch of the 213As were having issues on their own. By Dieter Hartmann about why the the early tests (Oct. 1944) of the Fw-190D-9 fell short vs. estimates/guarantees (here):



> Those first production engines produced 60-100PS less than the book values used for performance calculations.



(another reason being the differences between mock-up(s) and real airplanes)

We can note that really early 213As were produced almost a year before those tests (those went to the Ju-88/188), yet even with a year of the lead-in they were not making the advertised power.

Rinkol:



> In practice, the early DB603s had unacceptable reliability for single engined aircraft



Any good data about that (when the problem was encountered/remedied, etc.)? Maybe from an easily obtainable reliable source?


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## spicmart (Nov 21, 2012)

tomo pauk said:


> Care to elaborate the part about the Jumo 213E producing more thrust than 603L?



I don't quite understand. My source mentioned just that. And I am an absolute layman to answer those details.
But I'd like to know how this exhaust thrust is measured.


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## rinkol (Nov 21, 2012)

There is the circumstantial evidence: up to late in the war, the DB 603 was only used in twin engined aircraft (Do 217, He 219 and Me 410) despite promising performance figures obtained with some of the FW 190C prototypes.

Suzuki (Romance of Engines) mentions problems with the distortion of the cylinder liners.

Griehl's book (Do 217-317-417) makes numerous mentions of problems with the Do 217 engine installations and the effects of DB 603 engine shortages on production of this aircraft.

(pg 92) "The 100 hour engine endurance trials began at Rechelin on 21 December 1942, the pistons burning through after 91 hours. Testing of the newly installed DB 603A-2 inline engine was carried out beteen 28 April and 8 May 1943, but the program was beset by continual breakdowns and many defects and was abondoned."

pg 96 "As early as 2 June 1942 - at least from the viewpoint of Generalingenieur Eisenlohr - the DB 603 was at a stage of development which was far removed from any possible introduction into service. Defects in the transmission, oil circulation system and supercharger coupling all combined to frustrate the smooth performance that had been expected."

Pg 97

" ... it was realized finally [June 29, 1943] that the DB 603's unreliability and its unfitness for series production had thown the entire program into disarray. Only a modest requirement for equipping the HE 219 was assured of going ahead, albeit with many misgivings."

"For a few weeks in August 1943, it seemed as though all Do 217 variants which had been planned to have DB 603 engines would have to be abandoned"

pg. 97. 

"In September [1943] fresh reports had been submitted to the Luftwaffe leadership detailing the mass of defects in the DB 603. One such report, for example, originating in July stated that all 14 Do 217Ns of II/NJG 3 had been grounded with severe engine troubles." By October, the situation had deteriorated further ... " Apparently, the situation had reached the point where some aircraft were refitted with BMW 801s.

(pg. 212) "... in this period [Summer 1943], 107 sub-standard DB 603 engines alone were produced in June. In addition, a further 43 engines did not have crankshafts and were also useless."

It is also mentioned that plans to install DB 603s in five Ju 88s were abandoned.

There is also a reference in Irving's book on Milch to him making a negative comment about DB that probably refered to the DB 603 .

On the other hand, the DB 603 did not seem particularly troublesome in tests carried out by the allies on captured aircraft, at least judging rom Eric Brown's account of the Do 217 testing described in his book "Wings of the Luftwaffe". It may be that the main problems were eventually solved later in the war.

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## davebender (Nov 21, 2012)

RLM eliminated funding for the DB603 engine program during 1937. Some funding was grudgingly restored after the 1940 Mercedes-Benz T80 publicity stunt. The T80 was powered by the the third DB603 engine prototype (modified of course).

RLM couldn't kill the DB603 program completely because influential aircraft designers such as Dr. Tank wanted it. So they did what every bureaucracy does under these circumstances. RLM put a series of administrative obstacles in the way which prevented the engine from being fully developed and produced in large numbers.

Jumo 211 and Jumo 213 had the opposite situation. Almost unlimited support from 1937 onward. However it took Junkers longer then expected to achieve performance similiar to the DB603.


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## Tante Ju (Nov 21, 2012)

The Jumo 213A and DB 603A were practically identical engines in output, including high altitude output. They weighted pretty much the same, though visually the Jumo engine does seem to be a bit larger.


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## tomo pauk (Nov 21, 2012)

Rinkol, thank very much for the typing effort, appreciate it  You do make a strong case re. unreliability of the 603 in 1943.



spicmart said:


> I don't quite understand. My source mentioned just that. And I am an absolute layman to answer those details.
> But I'd like to know how this exhaust thrust is measured.



I'm not an expert, too. IIRC the exhaust thrust depends upon the weight of exhaust gases (more HP = bigger weight) and the gases' exit speed (should be about the same, for same altitude speed; design of the exhausts might intervene here). I'm obviously looking to be educated here


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## rinkol (Nov 21, 2012)

The German development programs were certainly beset by political infighting and many questionable decisions were made by senior officials.

On the other hand, it is not unusual for industrial organizations to find ways of blaming governement and other external factors for their own shortcomings. DB certainly must have made optimistic promises - among other things, the He 219 was originally designed around the DB 603G, an engine that was never really available. It also appears that they overextended themselves - there was a nearly unbelievable proliferation of engine development projects. While many of these were based to some extent on existing designs, the dispersion of resources would have militated against the overall prospects for the timely completion of projects. 

Junkers was not without their own problems. The cylinder dimensions of the Jumo 222 were changed three times with the last versions of the engine reverting to the original cylinder size. I think I've seen the expression "developed to death" in connection with this engine.


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## Shortround6 (Nov 21, 2012)

The "1940 Mercedes-Benz T80 publicity stunt" never happened. It was canceled so it is a little hard to see how it influenced things. 

Land speed record engines ( or water speed or even air speed) have darn little to do with service engines and anybody with any brains in anybodies air ministry knew it. 

The British got the old Napier Lion (designed in 1918) up to 1350hp for racing use by 1930/31 (or a bit more?). They never used a service engine at more than 600hp. 

Rolls Royce got their "R" racing engine (same bore and stroke as the Griffon) up to over 2500hp in 1931. 

Getting that power from gasoline instead of racing fuel and with service level reliability and durability took a few more years. 

Ground tests of the Merlin for the "Speed Spitfire" not only touched over 2100hp they held 1600hp for over 10 hours but it took another 5-6 years for a service Merlin to approved for over 2000hp. 

DB's own 601 racing engines used in the He 100 and Me 209 also show the same disconnect. Being pushed to over 2000 hp (or well over?) in 1939. 
3000hp in a record car might mean 1500hp (or less) from a serviceable aircraft engine.

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## Shortround6 (Nov 21, 2012)

tomo pauk said:


> I'm obviously looking to be educated here



Wish I could help but most of what I know (or think I know) comes from a Rolls-Royce Heritage book. A couple of NACA reports and some very scattered references/remarks. For example when Allisons were approved for WEP ratings the exhaust stacks had to sawed off as shortening them opened up the area to suit the higher exhaust flow. While the original size gave the best exhaust thrust at the original exhaust gas flow, the increased flow of the WEP airflow was restricted too much causing high back pressure and loss of crankshaft HP. 
Getting the exhaust thrust to give optimum power was quite a trick as the exhaust thrust varies with the weight of the "charge" (air+gasoline+any additives like MW50) and the gas exit speed as you stated. The charge weight varies with altitude slightly until critical altitude is reached, since even the temperature of the ambient air affects the charge weight. Above the critical altitude the charge weight drops as the the supercharger can no longer supply the volume (weight) of air as it did below the critical height. Exhaust speed is not only dependent on volume and exit size (assuming like exhaust passages) but the ambient air pressure. At around 20,000ft the air, having about 1/2 the air pressure of sea level, offers much less resistance to the exhaust so that the exit velocity can be several hundred ft/sec higher. 

Turning this variable exhaust thrust into exhaust power is even more difficult since the power is related to the speed. The faster you go the more power you get from the same thrust ( at least for most normal aircraft. Planes that exceed 1200-1400FPS may well show decreased power?) 

Even if you really, really know what you are doing you can only set up the exhaust stacks to be optimum for *ONE* flight condition. That is ONE throttle setting (boost level) at ONE altitude (both intake air pressure/temperature and exhaust back pressure) at ONE speed. 

I have no idea how wide a range of conditions you can get a useful benefit from if you try for a "general use" opening vs one that is too specialized or even if there is a "general use" opening. I would be wary of statements that say engine "A" had better thrust than engine "B" without some idea of what altitudes/throttle (boost) settings and speeds were being compared. It may be true or it may be that one engine was optimized for a different condition than was being tested.


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## rinkol (Nov 21, 2012)

I would think that, all things being equal, any differences in the exhaust thrust would result from differences in the velocity of the ejected exhaust gas. This is going to depend on the diameter and shaping of the exhaust stacks. Reducing their diameter might increase the exhaust velocity, but also increase the back pressure and thereby reduce the engine mechanical power. Consequently, there has to be some effort made to optimize the overall engine effectiveness. This is very speculative, but possibly the use of a single exhaust valve in a cylinder by the Jumo 213 might have altered the tradeoffs here.


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## davebender (Nov 21, 2012)

More RLM meddling. If it were up to Junkers the Jumo 222A engine and Ju-288 bomber would have entered mass production during 1942.


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## Shortround6 (Nov 21, 2012)

A boon to the allies. 

The Jumo 222 never worked properly in any of it's various incarnations. 

And which Ju-288? the 581 sq ft wing version, the 635 sq ft wing version, the 645 sq ft wing (or is it 696sq ft?) version?

Which defensive armament set up and what bomb load? both in a constant state of flux.

Estimated performance or actual tested performance?

And of course the Germans would have no trouble "what so ever" with the remote controlled guns and sighting periscopes ( which never really worked for anybody that tried them).

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## Siegfried (Nov 21, 2012)

silence said:


> I understand that Kurt Tank favored the 603 over the 213, being of the opinion that it was a better high-altitude engine. Why is this? What made it better for high-altitude use? Also, is there any special reason why they had their supercharger intakes on opposite sides, and could they have been reversed easily?



The Jumo 213 used a compression ratio of about 6.5:1 whereas the DB603 used a compression ratio of 7.5:1 and likely 8.5:1 for C3 optimised versions. The 603 also had more swept volume.

Thus the Jumo 213 would need to use considably higher pressure ratios to achieve the same power as the 603.

Hence the single stage supercharger on the 603 would have more reserve for altitude compensation.

Both engines moved towards two stage supercharges both with and without inter cooling.

The Db603 seems to have been ready nearly 1 year before the Jumo 213.

It seems to me that with the benefit of hindsight that the huge effort put into the DB604 could have been redirected to the DB603 and even 605 since the X24 DB604, despite its good test results was cancelled in favour of the Jumo 222. One would then at least expect the DB603 to level peg with the DB605 but with about 30 % more power well ahead of the Jumo 213 in timeline and also altitude performance.

Something like a Fw 190D13 or even Me 309 could have been in production around mid 43 in time to meet the P-51B onslaught starting December 43 with an engine offering better altitude performance than the BMW801 and about 15-20mph drag reduction. With potentially 2250hp on tap in early 44 some 444 mph should have resulted. A rather fast Ju 88S bomber or Ju 88G night fighter would have resulted.


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## GregP (Nov 21, 2012)

Exhaust thrust is not an issue at low power or cruise power. The only time exhaust thrust is important is at rated power or WEP, when all the power and speed you can get is what is needed.

Exhaust thrust depends on several factors including exhaust mass and volume. Another one is the shape of the exhaust manifold / pipe / pipes. If the area starts at the exhaust exit and decreases gradually to the end of the pipe, the exhaust increases in velocity, much as air does through the front half of a venture tube. It is usually called an “ejector” exhaust. That ALSO increases back pressure. SOME back pressure is needed for highly-tuned engines and exhaust systems. If the pipe starts at the exhaust exit and then slightly increases in area, then the exhaust velocity is reduced a bit and thrust is not likely a factor. If the area stays the same all the way down the pipe, then the exhaust velocity depends entirely on the exhaust mass and speed coming from the exhaust valve. The Mistubishi Zero had exhaust ejectors and they helped top speed by some 10 – 15 mph at full throttle and at critical height. Probably didn’t help much at takeoff or lower throttle settings.

I am not an expert on German engines, but the performance at altitude also depends on the supercharger gear ratio, impeller diameter, number of impeller blades, impeller design, smoothness of the stator intake and exit from the supercharger, and the shape and efficiency of the intercooler if so equipped. It is difficult to believe all these factors were identical for two engines developed by different companies, but not impossible. Probably one or the other had advantages, even if slight at particular heights. At max height, they could well be almost equal, so the nod SHOULD go to the one that is more reliable, with the better time between overhauls, and/or ease of maintenance service … in no particular order.

The Jumo 213 was perceived as a "bomber engine" by Kurt Tank and he told as much to the fighter pilots, but it gave yeoman service in the Fw 190D-9. It was a better engine than either the designer OR the pilots expected.

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## Tante Ju (Nov 22, 2012)

This may be interesting.

b = DB 603A
c = Jumo 213A

The DB engine is better at mid altitudes but the Jumo is just as good at high altitudes. Of course the DB 603 had a lot of room for development (as shown by the ultimate DB 603N).


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## tomo pauk (Nov 22, 2012)

Many thanks for the grapf, Tante Ju.



Siegfried said:


> The Jumo 213 used a compression ratio of about 6.5:1 whereas the DB603 used a compression ratio of 7.5:1 and likely 8.5:1 for C3 optimised versions. The 603 also had more swept volume.
> 
> Thus the Jumo 213 would need to use considably higher pressure ratios to achieve the same power as the 603.
> 
> Hence the single stage supercharger on the 603 would have more reserve for altitude compensation.



You did not stated the RPM, the 3rd part of the 'power triade'. Jumo-213 was making 3250 rpm for Notleistung, 603A was doing 2700; for Steig Kampfleistung it's 3000 vs. 2500. A 20 or 25 % bonus at RPM of Jumo-213A was able to practically cancel the 26% displacement advantage of the DB-603



> Both engines moved towards two stage supercharges both with and without inter cooling.



Agreed. But way too late to make a point in ww2.



> The Db603 seems to have been ready nearly 1 year before the Jumo 213.



As seen from previous post(s), the 603A was a troublesome item in 1943. 



> It seems to me that with the benefit of hindsight that the huge effort put into the DB604 could have been redirected to the DB603 and even 605 since the X24 DB604, despite its good test results was cancelled in favour of the Jumo 222. One would then at least expect the DB603 to level peg with the DB605 but with about 30 % more power well ahead of the Jumo 213 in timeline and also altitude performance.



Hmm, maybe the DB needed to dump 603 and concentrate to 628/605L, the two stage engines?



> Something like a Fw 190D13 or even Me 309 could have been in production around mid 43 in time to meet the P-51B onslaught starting December 43 with an engine offering better altitude performance than the BMW801 and about 15-20mph drag reduction. With potentially 2250hp on tap in early 44 some 444 mph should have resulted. A rather fast Ju 88S bomber or Ju 88G night fighter would have resulted.



Well, with a full 1943 to work out the bugs out of 603A (during that time maybe banning the Notleistung, as in 601E/605A case?), the engine became reliable in late 1943/early 1944. The early Fw-190/603A, with debugged engine would be a performer. So would be the Fw-190/213A (like the future D-9), but someone decided that 1st Jumo-213As are of better use in twin engined planes. Hence the LW was forced to make do during daylight with, now sub par, Fw-190A-7/A-8 and Bf-109G-6 just in time the USAAF deployed P-51B/C and increased the range of it's P-47s.
The DB-603 with 2250HP for 1944 would need a more significant push by RLM and canceling some resource-eating DB projects, earlier in the war.


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## cimmex (Nov 22, 2012)

tomo pauk said:


> The inital batch of the 213As were having issues on their own. By Dieter Hartmann about why the the early tests (Oct. 1944) of the Fw-190D-9 fell short vs. estimates/guarantees (here):
> 
> 
> 
> Any good data about that (when the problem was encountered/remedied, etc.)? Maybe from an easily obtainable reliable source?


 
I think you meant “Dietmar Hermann”, not Dieter Hartmann. In the link you provided the report is translated to English but it seems the appearance with the FW logo should make it more credible, hmm there is a bad smell...Never found those figures in one of Dietmar Hermann’s books. I think he is no member here because afaik he does not like all the “what if “ scenarios here but is more interested in real facts. I’ll send him a PM in another forum where he is a member too and looking forward to his comment.
cimmex


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## tomo pauk (Nov 22, 2012)

Dieter Hartmann? Boy, I should know better 



> I think he is no member here because afaik he does not like all the “what if “ scenarios here but is more interested in real facts.



No real facts here?



> In the link you provided the report is translated to English but it seems the appearance with the FW logo should make it more credible, hmm there is a bad smell...Never found those figures in one of Dietmar Hermann’s books.



The German charts, as posted in Williams' site, are in agreement.



> I’ll send him a PM in another forum where he is a member too and looking forward to his comment.



Cool, please share the data here.


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## krieghund (Nov 22, 2012)

Here's a chart of the Ju213A vs DB603E and excerpts from a Air Ministry doc discussing engine powers and exhaust thrusts.


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## tomo pauk (Nov 22, 2012)

Thanks for the chart, kriegund. The 603 represented there was the DB-603E, the version with enlarged supercharger, not the 'plain' 603A.


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## Siegfried (Nov 22, 2012)

While I agree with the point about the higher permissable RPM of the Jumo 213 versus the DB603 cancelling out the greater swept volume of the DB603 the advantage of the higher CR still remains though, doesn't it? The Higher CR should provide around 10% more power at the same compression or the same power at roughly 10% less boost. Indeed the Jumo 213J was supposed to opperate at 3750 rpm for 2700hp. I don't think the Jumo 213 however got to the RPM you mentioned till late in 44 or even 45.

The DB603A was somewhat troublesome in its first 6 months of service but it soon enough broke through to 100 MTBO barrier in early 1944. The PW R-2800, BMW 801 were all roughing it at around 25 hours when they first went into service. The CW R-3350 was still problematic when the aircraft flew its first missions in June 1944, I believe the 5 upper rear cylinders needed replacement at 25 hours due to burned out valves and poor cooling flow there. Low MTBO doesn't preclude effective service though it does preclude large scale service due to the heavier than usual maintenance requirements.

The DB603 also saw service in two variants, the standard DB603A and the DB603AA which compromised takeoff power a little in return for considerable extra power at altitude. Before the end of 1944 another variant, the DB603E was entering production. It had about 5% more low altitude power than the DB603A and at about 1800hp also had about 5% more high altitude power than the DB603AA.

The DB603EM also would have allowed the Ta 152C to enter service in late 1944. It produced 2260hp and was essentially a DB603E with MW50 but unlike the the plain DB603E it needed C3 fuel to exploit its Water Methanol injection system.

The German production schedule for a massive increase in C3 fuel production was starting to ramp up in late 1943 as new plant and new technology came on line only to be disrupted by the bombing campaign and endless fighters now opperating from the continent after d-day. Hence the DB603LA, which had a two stage supercharger (without intercooler I believe) and DB603L (with two stage supercharger and intercooler) had to be subsituted as both could produce serious levels of power with MW50 but without the use of the temporarily dubious C3 fuel.

Hence the oil campaign seems to have derailed the Ta 152C production by several months by forcing the Luftwaffe to emphasise more fuel flexible engines meaning that the Jumo 213E powered Ta 152H entered production first. About 4 Ta 152C with DB603LA engines were delivered.


My Hitchcock book on the Ta 152 notes the Jumo 213 was delayed by the effort expended on the Jumo 222. It seems fair to assume that the DB603 was also delayed by the effort on the DB604 as well as the 'suspension' by the RLM. The DB605 afterall contained no new suprises compared to the DB601 and DB605: it was merely a pantogram scale up.

Jumo 222 was back on the production schedule in 1944, it was probably derailed by the Normandy Landings. The Jumo 22E/F had superlative high altitude performance.

Daimler Benz for instance should have been able to get the DB603EM in production the same time it got the DB605AM in service on Me 109G6Am: about March 1944 while the DB603E should have been in large scale service by 1942 around the same time the DB605A entered service and solidly reliable before 1943.

That gives a range of options to existing aircraft such as the Do 217, Ju 88, Ju 188 and Me 410 all of which become much faster helping both the bombers survice but the night fighters such as the Ju 88G would be much more effective. A Me 410 with 2260hp engines also looks a lot more capable than one with 1750hp. Even the DB603E added about 2km to full pressure altitude to the DB603A.


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## tomo pauk (Nov 22, 2012)

Siegfried said:


> While I agree with the point about the higher permissable RPM of the Jumo 213 versus the DB603 cancelling out the greater swept volume of the DB603 the advantage of the higher CR still remains though, doesn't it? The Higher CR should provide around 10% more power at the same compression or the same power at roughly 10% less boost. Indeed the Jumo 213J was supposed to opperate at 3750 rpm for 2700hp. I don't think the Jumo 213 however got to the RPM you mentioned till late in 44 or even 45.



Be it what it was, the performance advantage was not 10%. It was 25 PS at 700 ft (~220 m) higher altitude. The 213A was providing 314 lbs of exhaust thrust (3250 rpm, 18000 ft), the 603A making 284 lbs (2700 rpm, 18700 ft) - the performance of the fighter with either engine is bound to be about the same, more so if we allow for typical production tolerances.
The 213A was making 3250 rpm in time it was used in D-9, sure enough that was late 1944. I'd appreciate any good data about the capabilities in earlier aplications. 



> The DB603A was somewhat troublesome in its first 6 months of service but it soon enough broke through to 100 MTBO barrier in early 1944. The PW R-2800, BMW 801 were all roughing it at around 25 hours when they first went into service. The CW R-3350 was still problematic when the aircraft flew its first missions in June 1944, I believe the 5 upper rear cylinders needed replacement at 25 hours due to burned out valves and poor cooling flow there. Low MTBO doesn't preclude effective service though it does preclude large scale service due to the heavier than usual maintenance requirements.



I can readily agree that 603A was a reliable engine from late 1943/early 1944.



> The DB603 also saw service in two variants, the standard DB603A and the DB603AA which compromised takeoff power a little in return for considerable extra power at altitude. Before the end of 1944 another variant, the DB603E was entering production. It had about 5% more low altitude power than the DB603A and at about 1800hp also had about 5% more high altitude power than the DB603AA.
> 
> The DB603EM also would have allowed the Ta 152C to enter service in late 1944. It produced 2260hp and was essentially a DB603E with MW50 but unlike the the plain DB603E it needed C3 fuel to exploit its Water Methanol injection system.



If it looks like I'm bashing the DB-603, I don't. The LW would've been better off with it in Fw-190 airframe from late 1943. My point is that Jumo 213 was a fully competitive engine, and RLM and/or Focke Wulf dropped the ball here too by not making available the Dora in early 1944.



> The German production schedule for a massive increase in C3 fuel production was starting to ramp up in late 1943 as new plant and new technology came on line only to be disrupted by the bombing campaign and endless fighters now opperating from the continent after d-day. Hence the DB603LA, which had a two stage supercharger (without intercooler I believe) and DB603L (with two stage supercharger and intercooler) had to be subsituted as both could produce serious levels of power with MW50 but without the use of the temporarily dubious C3 fuel.
> 
> Hence the oil campaign seems to have derailed the Ta 152C production by several months by forcing the Luftwaffe to emphasise more fuel flexible engines meaning that the Jumo 213E powered Ta 152H entered production first. About 4 Ta 152C with DB603LA engines were delivered.
> 
> ...



Germany have had a few really great engines, and many that were not worth the commitment, eating out the ever smaller resources. Same goes for main Allied countries (bar the resource situation), but Germany did not have one or more allies capable enough to help out in time of need.


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## davebender (Nov 22, 2012)

Daimler-Benz had difficulty obtaining machine tools for DB603 and DB605D engines. By 1944 Daimler-Benz management described the machine tool problem as gruesome. Meanwhile Junkers had little difficulty obtaining machine tools for the Jumo 213 engine. Type XXI submarine program, V1 cruise missile and V2 rocket programs had plenty of machine tools too. 

We will never know for sure how fast Daimler-Benz V12 engines could have been developed and produced. However it's readily apparent Daimler-Benz wasn't at the top of the food chain.


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## spicmart (Nov 22, 2012)

So the DB 603N and Jumo 213J versions were the peak of the development of these engines? Power output was the same? I wonder what max power for a RR Griffon would be possible?
Could those engines be further improved so that thea can match the Napier Sabre?
What power was the projected Jumo 213S supposed to have? It was a low altitude engine afaik.


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## johnbr (Nov 22, 2012)

The Ju-213s was to put out about 2500hp to 2600hp the DB-603n 2800hp to 3000hp the DB-603Q 2400hp the Q was a very high ceiling version of the DB-603N.


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## Siegfried (Nov 23, 2012)

spicmart said:


> So the DB 603N and Jumo 213J versions were the peak of the development of these engines? Power output was the same? I wonder what max power for a RR Griffon would be possible?
> Could those engines be further improved so that thea can match the Napier Sabre?
> What power was the projected Jumo 213S supposed to have? It was a low altitude engine afaik.



The 213J had a 4 valve instead of 3 valve head as well as extraordinarily higher RPM, the 213S had provision for incorporation of armour for low altitude work, it may have been similar to the 213J or the oversized valve 3 valve 213EB.

History show that the poppet valve matched the sleeve valve in RPM and thermal capability.

I came across one poster who said that Junkers were hoping to get to 3200hp eventually with the 213 though I haven't been able to confirm.


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## spicmart (Nov 23, 2012)

So the Jumo had the same development potential as the DB and the other engines in that class, but does higher RPM also mean more wear?


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## Shortround6 (Nov 23, 2012)

Higher rpm can mean more friction ( it goes up with the square of the speed). It means higher loads on the reciprocating parts and on the main bearings and crankcase areas supporting them ( again going up with the square of the speed). 

More wear is a lot harder to figure. If you don't know the materials or manufacturing processes or other factors than it is just wild guesses. Changing the material in the piston rings can give much more "wear". A different surface finish in the bore can change the wear. Changes in the alloys used in "plain" bearings to silver alloys greatly extended life (not use in car engines because anti-scuff additives in oil attack and corrode the silver alloys). The last is a good example of how certain combinations may give good life and other combinations poor life. Silver alloy bearings and "plain" oil and non-silver bearings with "trick" oil both give good life. Silver alloy bearings and "trick" oil give short life. 

If the block and crankshaft are beefed up to handle the load/s then the higher rpm is not a problem. The Allison 12 counter weight Crankshaft weighed 27lbs more than the older crankshaft but the loads on the bearings were markedly lower at 3200rpm than the older crankshaft loads were at 3000rpm. 

In the interest of saving weight few aircraft engines carried any more counter weighting than they needed to run at their maximum rpm. Few (if any) companies built heavier crankshafts ( heavier counter weights) to allow for future increases in RPM. 
AN increase of even 100rpm sometimes meant a new crankshaft if not a new ( or heavier) crankcase. 
Late war Allsions, Merlins and P&W radials had overhaul lives around double of the early war engines despite the increases in power due to changes in materials, manufacturing processes and design. If the higher RPM is taken into account soon enough in the design process and enough time/energy is spent on it it may not be a problem.

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## Siegfried (Nov 23, 2012)

spicmart said:


> So the Jumo had the same development potential as the DB and the other engines in that class, but does higher RPM also mean more wear?



Both the DB603N at 2800hp, Jumo 213J at over 2600 and BMW 801F at 2600hp were pushing towards 3000hp on fairly ordinary fuels.

In general it can be said that Junkers and DB had come up with solutions to the problems posed by high piston velocity etc. Junkers targeted high RPM and I believe was quite successfull with a war booty Jumo 213 benching at RR quite enlightening. Pistons are not round in cross section nor are they cylindrical so as to accomodate the asymetrical cranking forces, there is a myriad of detail in metallurgy and piston rings and I lubricants that can provide the necessary protection. Books are written on the subject of pistons. There were apparently some breakthroughs in this area on the DB604. 

There were a few tricks as well such as variable length inlets ports on the DB engines and I suspect that the variable timing exhaust valves planned for the 18 cylinder BMW802 would have shown up on the 801.


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## spicmart (Nov 24, 2012)

Thanks for the answers gentlemen. Maybe some of you can explain why the DB whilst being bigger sizewise has about the same weight as the Jumo?


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## Shortround6 (Nov 24, 2012)

Simple, See the part about the stress on the reciprocating parts, crankshaft and crankcase going up with the square of the speed (RPM). IF both engines were the same size (pistons and stroke) a 3250rpm engine has almost 45% more stress to deal with than a 2700rpm engine. Granted in real life the Bigger pistons moving a greater distance cause more stress than smaller parts would but the total stress still comes out lower so the bigger engine can use proportionally lighter parts. 

Aircraft engine designers (and especially airframe makers) never really cared about the power per unit of displacement as much as they did about power per pound of engine weight. A lighter engine of the same power allows you to carry more fuel or payload (weapons or cargo), Airframe maker doesn't care how the engine maker does it as long as the engine is reliable.


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## Siegfried (Nov 25, 2012)

spicmart said:


> Thanks for the answers gentlemen. Maybe some of you can explain why the DB whilst being bigger sizewise has about the same weight as the Jumo?



The DB 600 series didn't use bolts and nuts to hold on a seperate cylinder head to the cylinder block. It used a monoblock cylinder block plus head which I believe used a sort of giant nut tightened onto a threaded cylinder liner fastening the monoblock head to the crankcase. This kept head stresses even and reduced the need of a thicker cylinder wall to accomodate the bolt holes. There is more than one way to skin a cat and I rather suspect that the inverted mounting technique may have been essential to service.


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## Tante Ju (Nov 25, 2012)

spicmart said:


> Maybe some of you can explain why the DB whilst being bigger size wise has about the same weight as the Jumo?



I have seen a DB 603 and Jumo 213 next to each other. And while their main external dimensions may be the same, the Jumo was quite visibile a lot more massive engine! 

I suppose the Jumo probably needed stronger (and thus heavier) parts to compensate for the very high rpm. Also drilling bigger holes into a piece of metal (ie. a larger displacement engine with bigger cylinders) should make the block lighter, not heavier

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## Shortround6 (Nov 25, 2012)

Tante Ju said:


> Also drilling bigger holes into a piece of metal (ie. a larger displacement engine with bigger cylinders) should make the block lighter, not heavier



Ah, no. The engine "blocks" were not bored out of solid metal for the cylinder liners. The blocks were mostly hollow to accommodate the water (liquid) cooling passages. You had an outer block wall to contain the coolant and provide most of the strength in beam. You have the inner jackets/walls which hold the liners and were sometimes cut away to allow direct contact between the fluid and the liner. If the inner jacket/wall is too thick it hinders cooling. Aircraft engine makers did not make over sized blocks like car makers to "allow" for later growth. All that is left is a top deck _IF_ the engine used a separate cylinder head from the cylinder block. and some times a bottom deck, some engines used the top surface of the crankcase as the "bottom" of the cylinder block.

While not a DB 603 this picture of a damaged db601/605 shows the amount of empty space inside the cylinder blocks.

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## alejandro_ (May 12, 2013)

I was looking for information on the Fw 190 C when I came across this thread. Dietmar Hermann's book on Fw 190 "Long Nose" states:

_



"In contrast with to the Jumo powered Fw 190 D-9 which came later, the DB 603-powered Fw 190 retained its low-level climb rate better"

Click to expand...

_
Pag 23.

It also says that Daimler Benz believed the climb rate could be improved by 1-1.5m/s by installing a propeller with a broader blade.



> There is the circumstantial evidence: up to late in the war, the DB 603 was only used in twin engined aircraft (Do 217, He 219 and Me 410) despite promising performance figures obtained with some of the FW 190C prototypes.
> 
> Suzuki (Romance of Engines) mentions problems with the distortion of the cylinder liners.
> 
> Griehl's book (Do 217-317-417) makes numerous mentions of problems with the Do 217 engine installations and the effects of DB 603 engine shortages on production of this aircraft.



Rinkol, thanks for typing all that information. I am surprised these aircraft had so many problems with DB 603 because RLM considered Fw 190 C a low risk option. The trials went well and it seems that there were no issues with the powerplant. Maybe the installation in these aircraft had something to do?


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## Tante Ju (May 13, 2013)

Thanks SR6. It looks like very complex foundry technique. I wonder if the blocks were molded in a single piece, or somehow welded together later, ie. from two halves?

What I also wonder is the weight of the block itself. I suppose its very light, suggesting that most of the weight is coming from moving parts (cyl. heads, reduction gears, camshaft etc.).


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## tomo pauk (May 13, 2013)

I believe there was a question about exhaust thrust values of the 603A and 213A, and indeed the Jumo was faeturing some 20% more then the DB (open the picture in separate tab for hi-res):


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## spicmart (Mar 25, 2017)

With the Jumo 213j offering 2700 PS and the DB 603N 2800 PS the greater exhaust thrust of the Jumo should compensate for the slightly less power output.
After the war there were Arsenal engine projects using 213 parts.
Was the DB 603 ever subject of any post-war development?


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## tomo pauk (Mar 25, 2017)

spicmart said:


> ...
> After the war there were Arsenal engine projects using 213 parts.
> Was the DB 603 ever subject of any post-war development?



I don't think so. Winning coutries (those with resources) have had their hi-power piston engines both in development and production, with jet engines either flying or in experimental phase. Cash-strapped French were trying to use as much of German gear they could scavenge, whether piston or jet engines, whole aircraft or tanks.


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## spicmart (Mar 25, 2017)

Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).


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## tomo pauk (Mar 25, 2017)

spicmart said:


> Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).



That's interesting. Do you have any details?


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## stona (Mar 26, 2017)

spicmart said:


> Rolls Royce tested a Jumo 213 after the war. They obviously liked it (impressed?).



Roy Fedden wrote an article for Flight Global around the end of the war covering various German engine projects. This is what he wrote about the Jumo 213.

_"The 213 J 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 with high r.p.m."_

That, I would suggest, is damning with faint praise.

Cheers

Steve


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## Milosh (Mar 26, 2017)

Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?


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## stona (Mar 26, 2017)

Milosh said:


> Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?



He was writing on his return from Germany, to where he had led a mission to investigate the state of German aero engine development at the end of the war on behalf of the Air Ministry, so his comments were about German engines. In fairness to the Jumo, Fedden conceded that

_"...towards the end of the war, the Junkers 213 inverted V-12 liquid cooled type, rated at 2,200 h.p., was probably the best fighter piston-engine that Germany possessed."_

He made the point that both world wars had been fought with

_"inline or vee type liquid cooled engine, and the air cooled radial...with the exception that since 1918 designers have found how to make the radial cylinder arrangement work without whirling the whole engine around its crankshaft."_

In his opinion

_"The British, American, USSR, German and Japanese air forces all relied on these basic types for the war just ended, and the British Sabre stands out as the only breakaway to see considerable front-line operational service at high powers."_

But, he doesn't make any technical observations about the Sabre_,_ which, being an H-24, he saw as in a different class of engine to the inline or vee type liquid cooled, or radial engines on which he was commenting.

Cheers

Steve

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## Robert Porter (Mar 26, 2017)

My ignorance is showing, what type of engine was the Sabre?


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## stona (Mar 26, 2017)

Napier Sabre, a rather complex 24 cylinder liquid cooled engine which powered some British fighters like the Typhoon and Tempest.

It had a chequered development and history, but it was a powerful engine for the time (developing much more than the 1935 planned 2,000 h.p. by the 1944 version) and the issues were gradually overcome.

The Napier aero engine business, as Napier Aero Engines Ltd., became a subsidiary of Rolls Royce in 1962, its Eland engine may have something to do with that, and shortly thereafter the Napier identity was lost.

Cheers

Steve

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## Robert Porter (Mar 26, 2017)

Okay, now I found it, so it was not an inline or a "V" it was four opposed banks. Now I understand the earlier reference thanks!


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## tomo pauk (Mar 26, 2017)

stona said:


> Roy Fedden wrote an article for Flight Global around the end of the war covering various German engine projects. This is what he wrote about the Jumo 213.
> 
> _"The 213 J 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 with high r.p.m."_
> 
> ...



Germans were also upping the RPM (and with it the piston speed) of the DB 603 line, with 603N, that was supposed to run on 3000 RPM. Quite the turning speed for the engine with stroke of 180 mm, and with it the piston speed. IMO the upping of the RPM with Jumo 213J, that was also a bit over-bored vs. earlier 213s, while receiving a 4 valves per cylinder head was quite en achievement, and within the current trend in Germany, while that trend was barely present in the West.
The world 'abnormaly' is hardly an engineeing term.



Milosh said:


> Steve, what did R Fedden have to say about the Napier Sabre as it also had high rpm?



The Sabre was with short stroke, 121 mm, vs. 165 mm for the Jumo 213. On same RPM operation, the Jumo 213 will reach greater piston speed, by some 1/3rd greater than the Sabre.


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## stona (Mar 26, 2017)

"so it was not an inline or a "V" it was four opposed banks."

Napier engineer Frank Halford described it as a flat-H with liquid cooling and sleeve valves, which is about right 

Maybe the difference in RPM between the Sabre and an engine like the Jumo 213 is that the Sabre was always intended to run at relatively high RPM whereas the Germans increased the RPM of the Jumo 213 above that originally intended in an effort to squeeze more power out of it.
Napier had experience of small cylinder engines in an H configuration dating back to the 16 cylinder Rapier and its development into the 24 cylinder Dagger, though both were air cooled.

Cheers

Steve

Edit: The Sabre cylinders were 5 x 4.75 inches, tomo has already made the relevant comment about the short stroke/piston speed.


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## Robert Porter (Mar 26, 2017)

I remember a conversation I had with my grandfather about Piston stroke length. He said shorter stroke leads to higher RPM and more importantly higher heat generation and greater wear. It also required either more exaggerated lobes to drive valves or really tight gearing all of which also lead to higher heat and wear and shorter MTBF. But he mentioned military aviation engines had a very short working life in comparison to a typical car engine of the time. It was recognized that these engines would be frequently rebuilt or replaced over their operational life. Pushing an engine past its designed RPM limits typically resulted in timing issues and valve latency which usually resulted in a loss of performance and decreased reliability. Being an engineer for Pratt & Whitney he was fairly well acquainted with aircraft engines.


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## tomo pauk (Mar 26, 2017)

stona said:


> "so it was not an inline or a "V" it was four opposed banks."
> 
> Napier engineer Frank Halford described it as a flat-H with liquid cooling and sleeve valves, which is about right



Hmm - two boxer engines in layout, one laying atop of another, both boxers driving the same reduction gear, same superchager and axcessories; neither upper nor lower bank were able to run separately.



> Maybe the difference in RPM between the Sabre and an engine like the Jumo 213 is that the Sabre was always intended to run at relatively high RPM whereas the Germans increased the RPM of the Jumo 213 above that originally intended in an effort to squeeze more power out of it.
> Napier had experience of small cylinder engines in an H configuration dating back to the 16 cylinder Rapier and its development into the 24 cylinder Dagger, though both were air cooled.
> Cheers
> Steve



Jumo 213 was designed for high RPM from the get go, since 211 was bound to hit the RPM limit very soon, and indeed a further increase of RPM was a way to increase power further. Another way of incresing the power was increase of compression ratio, as tried on the 213EB than needed C3 fuel to operate. Plus of course the application of ADI, intercooling etc.
The Sabre got increase of RPM to 4000 in late models, plus ADI.


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## stona (Mar 26, 2017)

tomo pauk said:


> Jumo 213 was designed for high RPM from the get go, since 211 was bound to hit the RPM limit very soon, and indeed a further increase of RPM was a way to increase power further.



As far as I know the 213 was designed from the get go to run continuously at 3,000 r.p.m. The 213J was rated at 2,600 h.p. at 3,700 r.p.m. much above the original design speed.
Cheers
Steve


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## tomo pauk (Mar 26, 2017)

stona said:


> As far as I know the 213 was designed from the get go to run continuously at 3,000 r.p.m. The 213J was rated at 2,600 h.p. at 3,700 r.p.m. much above the original design speed.



I'm not sure that do you mean by 'continuously' here. The 3250 rpm was limited to 30 min (1/2 hour) for the Jumo 213E (= late 1944). Even the 213A was turning 3250 rpm by early 1944.
It is very much possible that there was enough of stretch in the design for 3700 rpm for short term power (5 min?) especially once the 3-valve head (from 213A to 213EB) was superseeded with 4-valve one (213J).

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## stona (Mar 26, 2017)

I have 3,000 rpm 'continuous' and 3,250 rpm 'take off' for the 213A, probably from Gunston or similar, hence the 3,000 rpm design parameter.

3,700 rpm was for the 213J (with the 4-valve head), but that's still fast for such a big engine, and way above the original design intention.

I can't find the originally intended speed for the Sabre anywhere, but I bet it was much higher than 3,000 rpm.

Cheers

Steve


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## wuzak (Mar 28, 2017)

tomo pauk said:


> Hmm - two boxer engines in layout, one laying atop of another, both boxers driving the same reduction gear, same superchager and axcessories; neither upper nor lower bank were able to run separately.



Technically the Sabre was a pair of 180° V-12s mounted together on a common crankcase.

A "boxer" or "horizontally opposed" engine has the pistons on opposite banks moving in opposite directions - both were heading outwards or both were heading inwards at the same time (ie when one was going left, the other was going right). 

A 12 cylinder boxer would require 12 crank throws and excessive length. Each piston would be connected to its own crank throw.

The Sabre's two cranks, on the other hand, were conventional 12 throw cranks as per normal V-12 usage. Pistons on opposite banks moved in the same direction - both left or both right.


It may be latter day usage, but engines such as the Sabre were still called in-lines, as were V-12s, even though their cylinders were not all in a line.

The Jumo 222 was described in British technical reviews as being a radialine - that is possessing features of both an in-line and a radial. That is there were several cylinders disposed radially around the crankshaft like a radial, while there were several cylinders (4) parallel to the crankshaft's axis.

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## wuzak (Mar 28, 2017)

stona said:


> I can't find the originally intended speed for the Sabre anywhere, but I bet it was much higher than 3,000 rpm.



I believe the original maximum speed for the Sabre was 3,700rpm. This was increased in later versions to over 3,800rpm and, in some circumstances, over 4,000rpm.


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## Shortround6 (Mar 28, 2017)

spicmart said:


> With the Jumo 213j offering 2700 PS and the DB 603N 2800 PS the greater exhaust thrust of the Jumo should compensate for the slightly less power output.
> After the war there were Arsenal engine projects using 213 parts.
> Was the DB 603 ever subject of any post-war development?



I don't know if a French factory was brought in as a subcontractor to Jumo during the war or if the French got parts/machinery/technical information after the war as "reperations" but without some sort of connection like that the post war 'career' of German WW II engines was going to be non-existent. The Germans weren't building anything, few people were going to want German products in any case.
The Military was turning to jets and the Americans pretty much had the civilian market sewn up. 

For the British, no civil aircraft was designed to use the Sabre engine, none were designed to use the Griffon. Only a few used the Merlin. However economics played a large part in that. The British and Commonwealth aircraft factories had to pay a pretty high import duty/tax on American engines after the war which made British/commonwealth engines more attractive. 
France was the only other European country with much of an aircraft industry in the late 40s. At least of a size to actually design/build large engines of a new or developed type. 

The Jumo 213 staggered on until at least 1953 in French hands if not later but power levels were pretty much held to Jumo 213A levels even with 100/130 fuel for production engines.

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## stona (Mar 28, 2017)

wuzak said:


> I believe the original maximum speed for the Sabre was 3,700rpm. This was increased in later versions to over 3,800rpm and, in some circumstances, over 4,000rpm.



Thanks for that. A much bigger percentage increase for the Jumo then.

Cheers

Steve


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