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Junkers Engines - Jumo 211
If that chart is accurate, the 211R seems more related to the 211F/J rather than the 2700 RPM N/P. Seems like it may have been a 211J with higher supercharger gear ratios and ending up with similar take-off power to the 211F due to the added intercooling.
The other suggestion (of putting emphasis on a higher altitude rated 211 sooner -at the expense of low altitude performance) still stands. If the 211R used a 2-stage supercharger arrangement similar to the 213A, that would be less directly applicable to potential earlier developments, but if it was closer to the single-stage unit of the F/J/N/P (or identical to it, but using higher gear ratios) then that indicates such developments should have been feasible to introduce considerably sooner. (doing so in parallel with the 211J's intercooler development seems attractive given the greater needs for charge cooling with higher supercharger compression ratios)Look here, it is 2700 rpm for the Jumo 211R. Problem with the 211R is that it was too late to matter - every 211 built in 1944 means one 213 less.
If using an intercooler closer to (or the same) size of that of the 211J, wouldn't it be possible to increase the supercharger speed (or use a larger/different supercharger) and end up with acceptable charge densities and temperatures? (perhaps close to the 211F's but with higher critical altitudes)Yes and no, the inter-coolers create drag, and the more you compress the air, say for high altitude work, the hotter it gets and the more airflow (drag) you need to cool the intake air. Now at high altitude where the air is thin the extra power more than offsets the extra drag and the plane will be faster. At lower altitudes the drag trumps the extra power and the plane is slower.
it is not the manifold pressure that counts here (1.42 Ata or whatever) but the amount of compression needed to get the outside air to 1.42 Ata (or whatever manifold pressure you are looking for).
The other suggestion (of putting emphasis on a higher altitude rated 211 sooner -at the expense of low altitude performance) still stands. If the 211R used a 2-stage supercharger arrangement similar to the 213A, that would be less directly applicable to potential earlier developments, but if it was closer to the single-stage unit of the F/J/N/P (or identical to it, but using higher gear ratios) then that indicates such developments should have been feasible to introduce considerably sooner. (doing so in parallel with the 211J's intercooler development seems attractive given the greater needs for charge cooling with higher supercharger compression ratios)
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The engine installation in a fighter being a much larger fraction of the total drag than the engine installation/s on a bomber.
We may be able to find the weight of the intercooler on the 211J but you are aiming at a moving target.
Running the supercharger faster and compressing the air more for better altitude performance is going to heat the intake charge more and require a larger inter-cooler and and higher mass flow of cooling air than the "J" needed.
Was that single-stage Jumo 213 still used the swirl type inlet/throttle guide vanes, right? Was it also intercooled?The 213A was using 1-stage S/C, not two stage S/C. The 2-stage unit was introduced with Jumo 213E.
Similar or better fire with the hub cannon, yes. (either an MG 151/20 or MK 108 should be more destructive than the pair of MG 131s, let alone preceding MG 17s). Drag might be a better than Jumo's standard annular radiator with a more streamlined one adapted specific to the 190 airframe. (plus, moving the radiator further aft, below the engine or fuselage should give better control over CoG while still keeping coolant lines and intercooler ducting short)The engine + intercooler will have a bit less drag than even the tightly cowled BMW 801, plus there is a weight save and less consumption. Weapon drag will be also smaller for same firepower, assuming prop cannon is installed instead of cowl HMGs.
Sticking with the existing 211F and J as the basis might have advantages in reliability over the 605 too. (DB 601 with intercooled DB 603 supercharger would have been interesting, intercooled DB-605AS certainly too though again there's the bearing lubrication issues)With that said, the intercooled DB 601/605 engines would be also interesting choices for the Fw 190.
Weight would be a bigger consideration on a single engine fighter (cockpit/pilot/armor, fuel tankage, and engine weight would all be bigger considerations on a single engine fighter). And unless you use a push/pull arrangement, the twin engine examples have the full engine nacelles adding to drag rather than the engine sharing some of its drag with the fuselage.It was the other way around - powerplant drag of 2-engined aircraft represented a bigger percentage of the total drag than on the 1-engined A/C in ww2. Eg. - Welkin started with powerplant drag being 19.4% of total drag, the Beaufighter was at 35.4%, Mossie and Whirly being in between. Spitfire was at 16.5-18 (Merlin 45) and at 19% (2-stage Merlin); British calculated the Fw 190 with 21.5%. Per tables kindly provided by Neil Stirling a short while ago.
From what I recall, the 211J intercoolers were also still fairly compact, fitting into an annular radiator cowling of the same diameter as the 211F but filling in some holes/gaps present between the coolant radiators.The intercooler was also a radiator - ie. it is of air-to-air type. The weight should be pretty low? The compressed air exited through the tube (42a), entered the intercooler and exited it, to enter the tube 4
It was the other way around - powerplant drag of 2-engined aircraft represented a bigger percentage of the total drag than on the 1-engined A/C in ww2. Eg. - Welkin started with powerplant drag being 19.4% of total drag, the Beaufighter was at 35.4%, Mossie and Whirly being in between. Spitfire was at 16.5-18 (Merlin 45) and at 19% (2-stage Merlin); British calculated the Fw 190 with 21.5%. Per tables kindly provided by Neil Stirling a short while ago.
The intercooler was also a radiator - ie. it is of air-to-air type. The weight should be pretty low? The compressed air exited through the tube (42a), entered the intercooler and exited it, to enter the tube 44a:
The fighter with the Jumo 211J will fly faster than the Ju 88 with the same engine - 100 km/h faster on same settings, or 25% faster, for 25% more air flow?
Even assuming those figures stayed static (given whatever radiator configuration employed), there's still the question of: is it worth it relative to what alternative?Say you pick up 100hp at the prop but the inter-cooler is costing you 50hp in drag, is it worth it?
Was that single-stage Jumo 213 still used the swirl type inlet/throttle guide vanes, right? Was it also intercooled?
Sticking with the existing 211F and J as the basis might have advantages in reliability over the 605 too. (DB 601 with intercooled DB 603 supercharger would have been interesting, intercooled DB-605AS certainly too though again there's the bearing lubrication issues)
(plus, moving the radiator further aft, below the engine or fuselage should give better control over CoG while still keeping coolant lines and intercooler ducting short)
Come to think of it, I don't recall any mention of the DB 603 suffering from bearing issues. Had it avoided use of roller bearings from the start and incorporated more satisfactory alternatives than the DB 605? (or at least compared to the initial production DB 605) If that was the case, might it have made more sense to forgo DB-605 production altogether in favor of more DB 603s as DB-601 production wound down?
For that matter, the 211J entered production ad service much earlier than the 605AM or D, and if tested/rated for higher boost with C2/C3 fuel, should have outstripped the 605A's performance without water injection, or possibly even approach the 605AM's at critical altitude.
From what I recall, the 211J intercoolers were also still fairly compact, fitting into an annular radiator cowling of the same diameter as the 211F but filling in some holes/gaps present between the coolant radiators.
Sorry, I don't think I was very clear with my phrasing before. I'd meant to say that the 211J's arrangement is generally more useful all around than a hypothetical 211F with similar power levels achieved through water/rich mixture injection. (an overboosted 211F running C-2 or C-3 might be more useful, but it won't help altitude performance any)The intercooler on the 211J may have been there as much for climb performance on the bomber as it was for speed. You are trying to get a 26-31,000lb bomber up to operating height and or improve ceiling as much as add 10-15mph to the speed. Water injection or rich mixture don't work well for long, hard climbs, you use up more Lbs of material (water or fuel) than the intercooler weighs. It could take a JU-88A-4 23 minutes to hit just under 18,000ft while weighing 27,557lbs. max take-off was 30,865lbs. The inter-cooler allowed operation at higher power levels for long periods of time and the shorter climb to altitued vs a non interecooled engine allowed for greater range on the same fuel. On a fighter it is different, the climb is much shorter only 1/3 or less of the time to get to the same altitude.
You don't think there's any way of managing an embedded or retractable radiator with significant improvements over the annular arrangement? (especially for the 211F without concerns for the intercooler)Radiator under fuselage - no-no IMO, it will be a speed brake. The CoG issues should be close to non-existant with the annular radiator, the Jumo 211 engines were much lighter than the Jumo 213 or DB 603A (and one of Fw 190s flew with DB 603 and without tail 'plug').
I was suggesting the 603 emphasis more in leu of the bearing shortages that forced some of the redesigns in transition from DB 601 to 605. (with continued use of ball bearings, the 601 -or alternate 605- might have had an easier time with higher RPM as well)It all depends on how long it would it take for the DB to sort out the 603A, and how good supercharger set-up is installed on the DB 601(E), plus whether it would be easy to rev-up the 601E to 2800 rpm, like the 605 managed eventually.
Larger single stage supercharged arrangements seemed to work well enough too (an intercooled DB-605AS should have covered most of the needs without resorting to a 2-stage arrangement or requiring water injection). The swirl/radial throttle guide vanes on the 213 also helped smooth power curves even better than the DB's fluid coupling in some respects. Having the latter available on the 211 earlier would have probably been more important than a 2-stage arrangement and probably more important than intercooling. (the upgrade from the crappy supercharger in the 211A-D series to the ones of the F was important for sure)As above - methinks that the DB 601E 605A would need less fiddling with, in order to achieve a bit better performance. Probably, the engine that 1st is to get a workable 2-stage S/C is the 'winner'.
Interesting that the 213A manages best power at the low altitude ends of its 2 supercharger speeds. I'as assume the critical altitudes would remain rather similar in height and power output for a simpler throttle plate configuration which implies the radial guide vanes actually improve power under dense air + restricted flow conditions and that a similar configuration applied to the earlier 211 models should have significantly increased their power at all heights outside of critical altitudes (or above 2nd speed crit alt) as well as making peak power output at SL. (possibly allowing the 211J to outperform the 605A, or the 211F to directly compete? -possibly without the added reliability problems suffered by the 211N depending what the cause of that actually was)To move a bit to the more powerful engines - the comparison between DB 603A (the original graph) with added lines for the Jumo 213A (blue) and BMW 801D (fully rated; thick red; thin red is for overboost above 1.42 ata). Above 6 km, the DB 603A (on B4 fuel) will make 10% more power than the 801D (C3 fuel), with perhaps main bonus being that overall drag will be decreased.
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You don't think there's any way of managing an embedded or retractable radiator with significant improvements over the annular arrangement? (especially for the 211F without concerns for the intercooler)
Larger single stage supercharged arrangements seemed to work well enough too (an intercooled DB-605AS should have covered most of the needs without resorting to a 2-stage arrangement or requiring water injection). The swirl/radial throttle guide vanes on the 213 also helped smooth power curves even better than the DB's fluid coupling in some respects. Having the latter available on the 211 earlier would have probably been more important than a 2-stage arrangement and probably more important than intercooling. (the upgrade from the crappy supercharger in the 211A-D series to the ones of the F was important for sure)
Interesting that the 213A manages best power at the low altitude ends of its 2 supercharger speeds. I'as assume the critical altitudes would remain rather similar in height and power output for a simpler throttle plate configuration which implies the radial guide vanes actually improve power under dense air + restricted flow conditions and that a similar configuration applied to the earlier 211 models should have significantly increased their power at all heights outside of critical altitudes (or above 2nd speed crit alt) as well as making peak power output at SL.
(possibly allowing the 211J to outperform the 605A, or the 211F to directly compete? -possibly without the added reliability problems suffered by the 211N depending what the cause of that actually was)
A retractable radiator would still have advantages in drag over a similar fixed radiator, wouldn't it? The He 100's example for takeoff/ground running is a bad example as it's not ducted/cowled. I'm thinking more in line with designs intended to be used in-flight like the single seater Fw 187 prototypes, He 111, and I believe some He 112 prototypes.A major source of the drag is the airflow through the radiator core or matrix. It depends on what the pressure drop is of the air moving through the radiator. A small area radiator with a high pressure drop is just as bad as a large radiator with a low pressure drop. This was part of what made the Mustang good. The air entered through the bottom scoop and the duct rapidly got larger which slowed the air before it hit the radiator core/matrix. the slower speed helped a lot because drag goes up with the square of the speed. The Mustang was trading volume inside the airframe for a low drag installation. Using short front to back radiator cores shoved out into the airstream (even part way) is like partially deploying an airbrake.
Thinking on this again, I had originally meant to imply more of a 'beard' type radiator under the nose (like P-40, Typhoon/Tempest, Ju 87, Bf 109A/B/C/D, etc) but that might not work as efficiently on an inverted V arrangement than an upright V. (or have few/no advantages over the annular placement) The P-40Q seems to have slimmed it down a good bit (and the P-40B/C was more streamlined as well, or at least appeared so aesthetically) but I'm not sure that would mean so much for the Jumo or DB engines. In all cases you'd still want some sort of ducting/cowling arrangement with boundary layer splitter and radiator cores shaped/placed accordingly. (having ram ducting and diffusion area like the P-51 used is another matter entirely and requires a lot more space)Radiator under fuselage - no-no IMO, it will be a speed brake. The CoG issues should be close to non-existant with the annular radiator, the Jumo 211 engines were much lighter than the Jumo 213 or DB 603A (and one of Fw 190s flew with DB 603 and without tail 'plug').
Agreed there, but I think the point of potential for an intercooled 605AS still stands. Similarly there should have been more room for single stage (with and without intercooling) growth on the 211 itself. The 213A seems to have maxed that potential out though, or come close enough. (same for the 605AS and the 603A)At 10 km and vs. DB 605A, the DB 605AS offered ~170 HP more (about equaling the Merlin 66), the DB 605L was offering 550+ PS more (like 2-stage RR Griffon). That is quite a difference.
I was more suggesting that the 211 might make better competitors had the swirl throttle been available sooner (and assuming Jumo got it working satisfactorily earlier than DB). The added power below critical altitude might make the 211F and J better for low level operation than the 601E and 605A (or at least more attractive with weight and production volumes in mind). 211N would be more interesting but as you mentioned also seems to have reliability issues, at least in testing on the Ta 154.I wouldn't be so sure that 211J (let alone the 211F, that was of lower power than the DB 601E already) will be outperforming even a restricted DB 605A. The 605A can still make 2600 rpm for 30 minutes, the 211J for 1 minute historically (take off only), and maybe 5 min in a faster flying fighter. The 605A has smaller drag due to the lack of intercooler, and it is even 4 cm narrower (not that it will mean anything for the installation on the Fw 190).
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Thinking on this again, I had originally meant to imply more of a 'beard' type radiator under the nose (like P-40, Typhoon/Tempest, Ju 87, Bf 109A/B/C/D, etc) but that might not work as efficiently on an inverted V arrangement than an upright V. (or have few/no advantages over the annular placement) The P-40Q seems to have slimmed it down a good bit (and the P-40B/C was more streamlined as well, or at least appeared so aesthetically) but I'm not sure that would mean so much for the Jumo or DB engines.
In all cases you'd still want some sort of ducting/cowling arrangement with boundary layer splitter and radiator cores shaped/placed accordingly. (having ram ducting and diffusion area like the P-51 used is another matter entirely and requires a lot more space)
Agreed there, but I think the point of potential for an intercooled 605AS still stands. Similarly there should have been more room for single stage (with and without intercooling) growth on the 211 itself. The 213A seems to have maxed that potential out though, or come close enough. (same for the 605AS and the 603A)