DB 603 vs Ju 213

[tomo pauk]

Many thanks for the grapf, Tante Ju.

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.

 

[cimmex]

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

 

[tomo pauk]

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.

 

[krieghund]

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

 

[tomo pauk]

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

 

[Siegfried]

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.

 

[tomo pauk]

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.


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.

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.

 

[davebender]

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.

 

[spicmart]

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.

 

[johnbr]

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.

 

[Siegfried]

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.

 

[spicmart]

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?

 

[Shortround6]

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.

 

[Siegfried]

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.

 

[spicmart]

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?

 

[Shortround6]

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.

 

[Siegfried]

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.

 

[Tante Ju]

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

 

[Shortround6]

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.

 

[alejandro_]

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"

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?