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An intercooler, in the case of the Jumo 211J or Merlin 60, is an liquid air heat exchanger that uses the cooling water from the standard radiator.
It does not increase frontal area, its a surprisingly small device. Cooling requirements might go up somewhat which would require a slightly larger radiator or wider open settings for the cooling gills.
This admittedly turned into a problem for the Fw 190D12 and D13 as they used a Jumo 213F (same as Jumo 213E but without intercooler). The more powerful C3 fuelled two stage supercharged engine generated more heat and so the radiator gills had to be kept open which increased drag. As a result the aircraft had after about a minute the same speed as the Fw 190D9. This was forced as result of an economy measure, using the same radiator as the Fw 190D9. The aircraft had better acceleration, climb and power to weight ratio as well as service ceiling. They decided to wait till the Jumo 213EB came out with the compact intercooler and enlarged radiator.
A 1 minute take-off rating for a Jumo 211J intended to get a bomber in overload condition off the ground before it ran out of runway might turn into a 3 minute WEP rating for a fighter at speed, since the airflow provides more cooling effect.
Intercooler is indeed a heat exchanger. The liquid-to-air system will need a radiator, pump, coolant fluid, tubing, regulation. Air-to-air intercooler is the radiator in the same time - simpler lighter, but might be not that flexible to install it.
The Jumo 211J used the air-to-air heat exchanger, the air was 1st compressed by the S/C, then routed down to the intercooler, then routed in the intake manifold. The intercooler used separate air stream vs. coolant and oil radiators.
Please note the bulge due to the intercooler, would it be worth to shoehorn it on the tightly packed Bf-109?
View attachment 290835
Air-to-air intercoolers were used in P&W turboed and 2-stage supercharged engines, as well as in turbo V-1710s. Once better intercoolers were installed in the P-38J, it gained a good deal of power, but some of the gain was consumed by increased drag.
2-stage Merlin used separate system to provide the coolant for its liquid-to-air intercooler, with, eg. in a Spitfire, a rectangular radiator slung under left wing, sharing the housing with the oil cooler. Cd0 went from 0.0213 (Spit V with 2 cannons + 4 LMGs) to 0.0229 (Spit IX with same armament). Sure enough, with hundreds of HP gained, intercooler it's radiators were low price to pay - not so much with proposed Jumo-211J installation on the Bf 109.
What would be the source for the claim that Jumo 213F used the same radiator as the Jumo 213A? Source for the Jumo 213F using C3 fuel?
The Jumo 213EB was to use the 'unitary' cooling system, with single barreled-shaped radiator. Main flow cooled the engine coolant, heat exchangers served the oil cooler and intercooler. Germany was in no position to wait for anything in late 1944/early 1945.
Let's say it is happens so. With all the pros cons of that installation, what is the gain vs. the Bf 109F4 with fully rated DB 601E or the Bf 109G2 with restricted DB 605A?
Its my assumption that the Intercooler on the Jumo 213E1, as used on the Ta 152H was already a liquid air type, the so called "warmtauscher" but the fact that the Jumo 211F was exactly the same engine without the heat exchanger might explain why the Fw 190D12/13 didn't receive the Jumo 213E1 and had to take the Jumo 213F but was expected to take the Jumo 213EB.
The use of an air to air intercooler creates a problem for Me 109 integration, I believe Avia succeeded in part.
The issue of oil/fuel resources and logistics came up here:I would not be so sharp, e.g. Operation Blau had sensible roots, Germany needed Causasian oil, Volga was an essential waterway to the SU and Stalingrad was an important industrial and transport center. Problems were Hitler's demand to try to conquer Stalingrad and Caucasus simultaneusly not one after another and the logistics. Did germany have capacity to reach Baku in 1942?
What if Germany had focused on securing the coastal regions more aggressively than deep penetration into Russia? Focus on securing/maintaining alliances/neutrality with Scandinavian states and invading/capturing the Baltic region, creating a land blockade on Russia?The governments in exile are likely going to cut deals with Hitler if Britain drops out, so they bring back their merchant shipping, while the end of the war and blockade means German shipping can come home from the neutral ports they were trapped in during the early war. Plus the Axis captured a fair amount of foreign shipping in the invasion of Norway and Western Europe. Britain didn't control all the waters of Europe, so its not as if they could legally inspect German shipping for contraband; they could cut sales of contraband once Germany invades the USSR, but not stop Germany trading with other neutrals. Britain didn't have the finances to give the USSR unlimited anything for free, plus its not as if the British conservative party, which had a visceral class hatred of the USSR, would supply the USSR with anything for free, rather they were more likely to sell them whatever they could afford and bank on Germany getting stuck in an endless occupation and low/medium level conflict in the East as the rump USSR continued to resist from Central Russia even if it wasn't able to drive out the Germans.
This is only comparing the existing DB-601E and 605A (the latter possibly not even existing in this scenario -or developing differently due to different resource limits), not potential models turned with lower FTH in mind, less charge heating, and less power consumed by the supercharger.The DB605A didn't get released for 1.42 ata boost till somewhere between june-October 1943. Thus for nearly a year the Jumo 211J produced more power, mainly down low.
Had the DB-603 been focused on during this period (over the 604 and possibly 605 as well -and 606/610 abandoned outright) might it have not been ready for mass production even sooner than any possible variant of the 222?Ju 288A was to weigh 11 tons, have 3 crew and required 2000hp of the Jumo 222A2/B2. The first two Ju 288A prototypes flew on BMW801 but the V3 and V4 flew on 2000hp Jumo 222A2/B2 before December 1941.
Requirements changed and the Ju 288B was speced to be a 4 man 14 tons aircraft, this required the 2500hp Jumo 222A2/B2, in fact it now required the Jumo 222E/F which had an two stage supercharger and intercooler.
I believe they were 211Fs salvaged from He 111s, the Heinkel nacelles being close enough to somewhat adequately adapt to the 109 airframe and there'd be no intercooler so not even a factor in this comparison. The broad chord prop and lower speed, higher torque reduction gearing made it a poor fit for both handling and high speed performance.The Avia copy was burdened with every draggy item from the late Bf-109s: HMG bulges, fixed tailwheel, bigger main wheels wing bulges to acomodate them, gondola cannons. Add the low power of the Jumo (211F?) and in 1946 you have a a fighter that is not even as good as Spitfire V.
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Had the Jumo 211N been adopted along with proper propellers and gear ratios more suited to a high speed fighter ... and had overall weight and drag additions elsewhere been compromised better (perhaps eliminating the nose armament entirely, and adopting internal cannon bays in the wings similar to how Adolf Galland's 109G had been modified, then perhaps they'd have ended up with a more adequately performing aircraft. (or, for that matter, if there was to be a Jumo 211 powered 109 in war-time German service, the configuration probably should have been closer to that ... though possibly including 211F powered variants -with proper prop/gearing- earlier on as well ... maybe retaining the MG-17 nose guns as well)
Or for that matter, with a better military/government in power, perhaps the 109T and carrier program wouldn't have been canceled (or would have been revived) and jumo powered variants of the 109T may have developed. (particularly if somewhat lower priority still went towards the Naval air support and refinements of the 109F perhaps didn't extend to the 109T to the same levels ... or simplifying development by retaining the existing wing structure and cannon armament, but upgrading the MG-FFs to MG-FF/Ms and then to MG 151s)
The issue of oil/fuel resources and logistics came up here:
http://www.ww2aircraft.net/forum/av...ofessionals-study-oil-production-43043-5.html
A lot was discussed but one big point was there were many alternate solutions for expanding German fuel production outside of greater access to crude oil. The shale oil reserves mentioned early on in the thread weren't all that viable to expand in the short term, but the synthetic fuel production using a variety of coal types and potentially biomass (wood waste, agricultural waste, any sort of plant waste able to be amassed and transported effeciently, potentially domestic and industrial waste/recycling programs as well -but the coal reserves was the main/immediate interest). A much broader array of synthetic fuel plants could have been dispersed and the infrastructure shifted more and more towards the much more efficient to produce fractions of the products from Fischer–Tropsch fuel plants -particularly methanol, ethanol, butanol, acetone and a few others. (ideally they should have made the shift starting pre-war, but the earlier the better -and in the interim, focus on producing the most efficient fuels still acceptable in the existing infrastructure; along with that, drop further investment in the far more costly hydrogenation based fuel plants, maintain the ones in service, and use the limited oil and liquid coal fractions to supplement synthetic liquid fuel production)...
No existing 211 allowed an engine cannon to be fitted, but that may have been more due to lack of demand than difficulties in mounting. (then again, the demand should have been there from the start with the 213, competing with the DB-603, and a motor cannon mounting lagged in production there as well)I'd propose also a deletion of cowl guns, installing the MG FFM in series (with apropriate strengthening of the wing) and use of 90-rd drum as used on mid-series Fw 190s, along with MG 151/20 as engine cannon; all for the historical Bf 109.
Improved take-off/landing performance (and reduction in accidents) may have been even more worthwhile, though the landing gear legs didn't get a wider track as the 109H did. (better climb and turn performance might also make the compromise in drag worthwhile)The 'big wing' Bf 109 should have had better rough strip take off and landing abilities, and/or should be able to take off with more payload, not just as a fighter, but also as a fighter-bomber. It would be also interesting as a hi-alt variant, not so 'drastic' as the Bf 109H.
The hispano cannons were far heavier and more powerful guns than the MG 151/20, the latter only moderately more powerful than the rounds used by the MG-FF/M, plus the 109F and G had already been able to carry 151s in gun pods underwing. Being able to physically fir the 151 and its ammunition into the 109's wings might be more the problem.The swap from MG FF to MG FFM was easy job, since those were basically the same as far as airframe is concerned. The next swap (from MG FFM to MG 151) will mean substantial change in the wing structure: for example, the Spanish redesigned the wing internals for their Buchon, that included going from 1-spar to 2 spars, in order to acomodate a 20 mm cannon more powerful than MG FFM.
That too was discussed in this thread http://www.ww2aircraft.net/forum/av...study-oil-production-43043-4.html#post1195777Before the war Göring initiated very ambitios synthetic fuel program but it was over-ambitious. The shortage of both steel and manpower had delayed the completion of the full construction program of hydrogenation plants most planned plants were not built also some of the planned Fischer-Tropsch plants were never completed and those completed were badly overdue. It doesn't matter how big heap of coal one has if one has only a limited processing capacity.
Higher altitude supercharger gearing is less relevant for the Eastern front, but if it had been in greater demand as a fighter engine alongside the 601/605, higher alt supercharger gearing may have been introduced sooner. (or maybe even earlier emphasis on a 2-stage supercharger, or water injection for that matter -the latter also useful for omitting intercooling and for allowing increased boost at low level on takeoff with higher speed single stage units) Without the strength increases and other changes in the valves and crankshaft of the 213, you still wouldn't be seeing higher power levels, but better power at a wider range of altitudes would be significant, and possibly better power sooner. (aside from WM/50, having increased boost ratings with C2/3 fuel would be notable -including potentially pushing 211F power levels closer to 211N)The production Jumo engines featured 3 valves per cylinder, vs. 4 valves of the DB engines.
I'm not sure whether the Jumo 211N/P/R received a better/bigger S/C, however the RPM was increased to 2700; the N and P should be able to match the DB 601E, though a year or two too late. The 211R should be able to match the fully rated DB 605A at altitude, but that is already 1944 we're talking about. The 211R sacrificed the take off power vs. the 211N (1350 vs. 1450 PS; probably a different S/C gearing was used, tailored more towards high altitudes). The DB 605A was at 1475 PS for take off.
No existing 211 allowed an engine cannon to be fitted, but that may have been more due to lack of demand than difficulties in mounting. (then again, the demand should have been there from the start with the 213, competing with the DB-603, and a motor cannon mounting lagged in production there as well)
That said, the MG FF/M with 90 round drums seems a reasonable enough weapon and (regardless of structural issues) the lower recoil of the API blowback weapons should make aiming at least slightly more consistent. (plus the velocity isn't too much lower than the 151/20 -lower rate of fire is a bigger drawback) Still, in the case of the jumo 211, assuming no ability to fit a nose cannon, the sole armament of 2 MG FF/M cannons would be useful enough. Pilots might prefer retaining the cowl guns too, but practically speaking, learning to not rely on those for ranging (or the few light targets they were effective against) might be preferable, especially with the differing ballistics of the guns. (well ... with the MG 131, ballistics would be closer and the HMG would be more useful in its own right)
Higher altitude supercharger gearing is less relevant for the Eastern front, but if it had been in greater demand as a fighter engine alongside the 601/605, higher alt supercharger gearing may have been introduced sooner. (or maybe even earlier emphasis on a 2-stage supercharger, or water injection for that matter -the latter also useful for omitting intercooling and for allowing increased boost at low level on takeoff with higher speed single stage units) Without the strength increases and other changes in the valves and crankshaft of the 213, you still wouldn't be seeing higher power levels, but better power at a wider range of altitudes would be significant, and possibly better power sooner. (aside from WM/50, having increased boost ratings with C2/3 fuel would be notable -including potentially pushing 211F power levels closer to 211N)
No existing 211 allowed an engine cannon to be fitted, but that may have been more due to lack of demand than difficulties in mounting. (then again, the demand should have been there from the start with the 213, competing with the DB-603, and a motor cannon mounting lagged in production there as well)
That said, the MG FF/M with 90 round drums seems a reasonable enough weapon and (regardless of structural issues) the lower recoil of the API blowback weapons should make aiming at least slightly more consistent. (plus the velocity isn't too much lower than the 151/20 -lower rate of fire is a bigger drawback) Still, in the case of the jumo 211, assuming no ability to fit a nose cannon, the sole armament of 2 MG FF/M cannons would be useful enough.
Higher altitude supercharger gearing is less relevant for the Eastern front, but if it had been in greater demand as a fighter engine alongside the 601/605, higher alt supercharger gearing may have been introduced sooner. (or maybe even earlier emphasis on a 2-stage supercharger, or water injection for that matter -the latter also useful for omitting intercooling and for allowing increased boost at low level on takeoff with higher speed single stage units) Without the strength increases and other changes in the valves and crankshaft of the 213, you still wouldn't be seeing higher power levels, but better power at a wider range of altitudes would be significant, and possibly better power sooner. (aside from WM/50, having increased boost ratings with C2/3 fuel would be notable -including potentially pushing 211F power levels closer to 211N)
All that said, with existing engines early-war and the 211F might at least have been a useful supplemental engine to the 601E and N, and better than the older 601A. (plus, didn't the 601E initially have boost restrictions that lessened its advantages over the 211F?)
It may have been lack of "demand". The Jumo 210 allowed for a gun through the prop. The BMW 116 is described in one book as having a hollow propshaft for a shell gun and the same book says the Jumo 211 allowed for one.
Hooker greatly improved the Merlin supercharger (added several thousand feet of full throttle height) by changing the inlet shape and keeping the same impeller/diffuser and pretty much the same gearing. The late 30s German superchargers were pretty crappy, but then so were most other peoples. speeding up the impeller with a gear change doesn't do much good if the intake shape is bad, or if the impeller is bad ( and the Junkers ones were very far from good). see fig | spiral volute | flight january | 1942 | 0144 | Flight Archive
Might be for the early Jumo 211 models, but the Jumo 211F/J have had the prop governing items (item group 55 on the pic) at the rear part of what would otherwise be gun barrel tube?
View attachment 291145
The pic of Jumo 211B/D does not have those items there, it shows an open rear part of the tube.
The 'box-wheel' supercharger of the Jumo 210 to 211B/D was judged by NACA not to be that efficient, with 59% peak efficiency on the 211A. The DVL designed S/C, installed on the Jumo 211F/J, have had the peak adiabatic efficiency of 76.6% and peak impeller efficiency of 82.3%.
Thank you. The basic engine had the tube/space. The Avia fighters were using parts on hand. A contract for several hundred engines place at the factory for delivery later could very well have had the prop governor items moved to a different location.
Previous times I've seen Junker's box-wheel impeller design, I'd assumed those outlets were static channels not part of the rotor ... that seems like an awful arrangement that would needlessly increase drag. I'd thought DB's partially shrouded arrangement was a bit unusual, but I hadn't realized it was in fact one of the better designs around.It is not the "gearing" in the supercharger you have to worry about. It is if the compressor (intake/impeller/diffuser) can make the pressure (and volume) needed at the altitude desired. Changing gears is relatively simple.
Hooker greatly improved the Merlin supercharger (added several thousand feet of full throttle height) by changing the inlet shape and keeping the same impeller/diffuser and pretty much the same gearing. The late 30s German superchargers were pretty crappy, but then so were most other peoples. speeding up the impeller with a gear change doesn't do much good if the intake shape is bad, or if the impeller is bad ( and the Junkers ones were very far from good). see fig | spiral volute | flight january | 1942 | 0144 | Flight Archive
With the drag from the air impacting the outside of the box-wheel impeller's channels and (as near as I can tell) swirling around pointlessly in the compressor housing, it seems like there'd be a lot of wasted power without necessarily resulting in charge heating. (or would that swirl and -my understanding of fluid dynamics is limited, but- what seems to me would be pockets of high and low pressure or pressure and partial vacuum left in the wake of those box channels result in all that wasted power going into heating the charge?)And thank you for the efficiency figures for the 'box-wheel'. If only 59% (at best) of the power going into the supercharger is going to actually compress the air that means that 41% (minus friction loss in the gear drive) is going into heating the air over and above the heat of compression. Spinning the impeller faster is going to lower the efficiency even more putting you in the land of diminishing returns.
Indeed, it seems the obvious choice and strange that 3x MG 151/20s wasn't the standard Fw 190D armament. (aside from the potential to carry an MK 108 in the nose instead)Getting rid of cowl guns in the V-12 powered Fw 190 and installing a cannon to fire through the prop not only increases the firepower, it cuts a bit of drag.
Yes, though with the poor Jumo supercharger design holding things back, the benefits from high compressor may have outweighed those of limited boost considerably more than they did on the DB engines. (with DB's relatively decent superchargers, using lower compression ratios and higher supercharger speeds -or adopting the DB 603's supercharger earlier would seem much more appealing -particularly as applying boost limits could potentially allow such engines to switch between using higher and lower octane fuels)An earlier introduction of MW 50, or rating the V-12 engines for C3 engines would've made the LW fighters extracting an even greater toll on Soviet aircraft. The Jumo 211 series might've been perhaps better users of C3 fuel, with their compression ratio of 6.5:1 (the DB 601E at 7.2:1, the 605A at 7.5/7.3:1) allowing for greater boost.
Granted, many times the German engine designers upped the compression ratio when tailoring the engine for hi-oct fuel, hence negating the chances for greatly increased boost levels.
With the introduction of that rather vastly superior supercharger design (though I'd imagine inlet design would still be a significant limiting factor apart from the compressor itself), the prospect of pushing the impeller speed to higher altitude ratings at the expense of take-off power seems more feasible, especially on models using the intercooler. (or had they adopted water injection earlier)The 'box-wheel' supercharger of the Jumo 210 to 211B/D was judged by NACA not to be that efficient, with 59% peak efficiency on the 211A. The DVL designed S/C, installed on the Jumo 211F/J, have had the peak adiabatic efficiency of 76.6% and peak impeller efficiency of 82.3%.
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I wonder if a superior supercharger design was one of the factors contributing to the Bramo 323's power output and altitude performance compared to other late 30s engines and especially given its displacement, and if so whether they considered applying that experience to their jet engine developments alongside the axial ones.
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Indeed, it seems the obvious choice and strange that 3x MG 151/20s wasn't the standard Fw 190D armament. (aside from the potential to carry an MK 108 in the nose instead)
I'm still curious to how a Jumo 211 with Jumo 213 derived supercharger may have fared, more so if it could have entered volume production earlier than the 213 itself.
I was speaking more in terms of comparing things to other German superchargers, but 1000 PS at 10,200 ft for the 323A, and I believe the low-alt gearing allowed 1,100 ps at a reduced critical altitude. The 2-speed models managed 940 ps at 13,000 ft which would be only slightly less than the 2-speed pegasus managed.Can't agree that Bramo engines have had that good altitude performance, were looking at maybe 700-750 HP at altitude? The Bristol Mercury have had 840 HP, and it was a bit smaller engine.
I wonder how those early supercharger designs compared to what Jumo was using immediately pre-war on the 210, 211, and diesel engines. With the sort of pressures/volumes needed on the L55, it seems a bit odd to resort to multi-stage designs, though.OTOH, Jumo might want to remember, early enough, of it's inter-war engines, the L 55 and L 88a, that were employing 2-stage superchargers, the L 55 even the 3-stage. All of those were hydraulically coupled to the crankcase.
I wonder how those early supercharger designs compared to what Jumo was using immediately pre-war on the 210, 211, and diesel engines. With the sort of pressures/volumes needed on the L55, it seems a bit odd to resort to multi-stage designs, though.
I was speaking more in terms of comparing things to other German superchargers, but 1000 PS at 10,200 ft for the 323A, and I believe the low-alt gearing allowed 1,100 ps at a reduced critical altitude. The 2-speed models managed 940 ps at 13,000 ft which would be only slightly less than the 2-speed pegasus managed.
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I wonder how those early supercharger designs compared to what Jumo was using immediately pre-war on the 210, 211, and diesel engines. With the sort of pressures/volumes needed on the L55, it seems a bit odd to resort to multi-stage designs, though.