AHC: the best possible Luftwaffe for 1940

Deleted member 1487

Pg. 86 of 'Flugmotoren und strahltriebwerke' book, part of book dealing with Jumo 211 series:

"Die Bauereihen A bis H hatten eine geschlossene Druckkuehlanlage..."
that translated by Google translate means:

"The construction series A to H had a closed pressure cooling system..."
I'm not sure that means pressurized, instead just the name of the liquid cooling system.
These sources say the Jumo 211 lacked such a system:
https://books.google.com/books?id=isMTDQAAQBAJ&pg=PT112&lpg=PT112&dq=jumo+211+cooling+system&source=bl&ots=hsYxkE5UHH&sig=ACfU3U2l9ZW9LQkXIHj9ymHvR1gBfzjSdA&hl=en&sa=X&ved=2ahUKEwiK09vazcDgAhXH7YMKHeEoB2AQ6AEwEnoECCMQAQ#v=onepage&q=jumo 211 cooling system&f=false

https://books.google.com/books?id=EqZio4ykVTUC&pg=PA48&lpg=PA48&dq=jumo+211+cooling+system&source=bl&ots=ysTeHhZEc5&sig=ACfU3U0PnfG9EsccvPf5zpmTJwaD9MDNPg&hl=en&sa=X&ved=2ahUKEwjx8bj2zsDgAhUD04MKHdoeD_wQ6AEwFHoECCEQAQ#v=onepage&q=jumo 211 cooling system&f=false

https://en.wikipedia.org/wiki/Junkers_Jumo_213
When the Jumo 211 entered production in the late 1930s it used an unpressurized liquid cooling system based on an "open cycle". Water was pumped through the engine to keep it cool, but the system operated at atmospheric pressure, or only slightly higher. Since the boiling point of water decreases with altitude (pressure) this meant that the temperature of the cooling water had to be kept quite low to avoid boiling at high altitudes, which in turn meant that the water removed less heat from the engine before flowing into the radiator to cool it.

By contrast, the 1940 Daimler-Benz DB 601E used a pressurized coolant system that ran at the same pressure regardless of altitude, raising the boiling point to about 110 °C. This allowed it to use considerably less water for the same cooling effect, which remained the same at all altitudes. Although otherwise similar to the Jumo 210 in most respects, the 601 was smaller and lighter than the 211, and could be run at higher power settings at higher altitudes, making it popular in fighter designs. The 211 was relegated to "secondary" roles in bombers and transports.

The Junkers Motorenwerke firm was not happy with this state of affairs, and started its own efforts to produce a pressurized cooling system as early as 1938. Experiments on the 211 proved so successful that it became clear that not only could the engine be built smaller and lighter (by reducing the water requirement),[2] but could be run at higher power settings without overheating. Additional changes to strengthen the crankshaft and add a fully shrouded supercharger for increased boost resulted in the Jumo 211F model, which delivered 1,340 PS (1,322 hp, 986 kW) at 2,600 RPM, up from 1000 PS at 2,200 RPM in the first version 211A.

Junkers L 88 engine, not Ju-88 aircraft, sorry for dropping the letter. Intercooler is mentioned at pg. 80 of 'Flugmotoren und strahltriebwerke' book.
'Jumo' (Junkers motors, roughly) got that name some time in mid/second half of 1930s.
The Jumo engines were listed as L1-L10 with the Jumo 210 being the renamed L10.
https://en.wikipedia.org/wiki/Junkers_Jumo_210
The first gasoline-burning aviation power plants that the Junkers Motorenwerke ever built, the L1 and L2 single overhead camshaft (SOHC) liquid-cooled inline-six aviation engines of the early and mid-1920s. Development of this line led up through the L8. All of these were developments of the BMW IIIa inline-six SOHC German World War I aviation engine, which BMW allowed as they were no longer interested in development of their WWI designs. The Junkers L55 engine, however, was the very first V12 layout aviation powerplant of any type created by the Junkers firm, using a pair of the earlier straight-six L5 engines as a basis for an "upright" liquid-cooled V12 aviation engine, as the contemporary BMW VI engine already was.

Development of the Jumo 210 itself started in 1931 under the designation L10. The L10 was Germany's first truly modern engine design, featuring three valves per cylinder,[1] an inverted-V layout, a supercharger as standard equipment, and a cast cylinder block. The 210 was odd in that the cylinders were machined into a block along with one side of the crankcase, two such parts being bolted together side-by-side to form the engine. Normal construction techniques used three parts, two cylinder blocks and a separate crankcase.

The L10 was first ran in static tests on October 22, 1932. With the official formation of the RLM in 1933, numerical engine designations by manufacturer was rationalized with Junkers receiving the "200 block", the L10 becoming the 210. Type approval was achieved in March 1934, and it first flew on July 5, 1934 installed in a Junkers W33. The design had initially aimed for 700 PS, but the prototypes delivered only about 600 PS, so there was some disappointment in the industry. Nevertheless, almost all German aircraft designs of the era were based on the 210, which is why they were so small compared to other countries' efforts.

The L88 appears to have been a different engine:
https://de.wikipedia.org/wiki/Junkers_Jumo_210
Then began in 1931 in Dessau , the Junkers engine GmbH under the direction of Otto Mader with the development of the Jumo 210. The new engine turned over its predecessor, the V-12 engine L 88 with vertical engine (crankshaft below) a generational leap because It was first designed by Junkers, taking into account the vibration behavior in the barrel. The predecessor was still trying to achieve a minimization of vibration by oversized components, but this led to a high weight with large moving masses . The through the optimized parts such as crankshaft, connecting rod , pistonetc. achieved weight reduction allowed much higher speeds, so that the Jumo 210 had only about half the power of the L 88.
Just because the L88 had an intercooler doesn't mean the Ju210 or 211 did, as I can find no reference to the intercooler before the Jumo 211J.
 
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Not sure those bigger drums fit in the wings of the Bf109E.
...

Check it out (T 60FF is a 60rd drum, T 90FF is a 90rd drum):

drummers3.jpg

drummers2.jpg


Right, because the Do217 was designed to carry heavy bombs internally, which meant making it quite a bit bigger. To carry the biggest bombs it had to be rated to carry 2-3 tons of weight and be large enough internally to actually fit them. The Do217 also had much more powerful engines, which even then left them underpowered in the initial versions. Having a light payload meant though that it was able to be faster; if you fit the Ju88 with BMW801 engines it would have been even faster than the Do217. Of course you're not factoring in the cost of the Do217 was considerably more due to the increased size and complexity of the design.

Those schematics are for the still-born Do-317 (4 tons max internal), not for Do-217 (3 tons max internal). Note the square-ish cross section, vs. triangle-ish of the Do 217. Also covered here.




BMW 801A and 801G were not the same engines, 801G was the sibling of 801D, 801A was even less powerful than 801C.
We can try bombing up both of the aircraft with 2000 kg of bombs, install 801D/801G on Do 217 and then measure speed.

As to it being underpowered, this is Eric Brown's take:
https://en.wikipedia.org/wiki/Dornier_Do_217#Flying_the_Do_217_M-1

Probably it was indeed undepowered. Note the max speed of 523 km/h per Brown.

Which is not what it was designed for. If you want a purely operational/strategic bomber there is already the He111, which was more capable in that realm. The Do217 wouldn't be around yet as it's engines aren't ready. The He111 was already in production, a mature design, was upgradeable still, and having fewer bomber types could boost production output.

I want operational/strategic Ju-88 all the time. He 111 demands good fighter cover over England, the, hopefully, fast Ju 88 is less dependant.

Ok, for the sake of argument let's go for that. How many more fighters does that yield?

If we exchange each Bf 110 made in 1939-40 for two Bf 109s, it is 1160x2=2320 extra 109s. Granted, we will not have much of use for the 109s produced in last 3 months, so it is perhaps 2000 extra before October 1940.
Production of Bf 109s in 1939-40 was 2100+ examples. Decreasing that number for 3 last months production = ~1800.
All said, going all out for Bf 109s more than doubles up their numbers during our time frame of interest. This is before we account for economies of scale.
 

I know this will sound cocky, but English language literature is often in collision with German literature, and I prefer to use the later for German hardware. The German word 'Druck' = 'pressure' in English in this case (can also mean print, strain, force). Also please see here, all Ju 88A bomber versions are listed as having 7500 m service ceiling ('Dienstgipfelhöhe') without bombs, be it with Jumo B, G or J engines.

BTW - the 'Powering the Luftwaffe' book at pg. 49 says that Jumo 213F have had a 3-stage supercharger - nope, not the case.

The Jumo engines were listed as L1-L10 with the Jumo 210 being the renamed L10.
https://en.wikipedia.org/wiki/Junkers_Jumo_210

The L88 appears to have been a different engine:
https://de.wikipedia.org/wiki/Junkers_Jumo_210

Just because the L88 had an intercooler doesn't mean the Ju210 or 211 did, as I can find no reference to the intercooler before the Jumo 211J.

L88 was a different engine, there was plenty of different engines. I've never claimed that any Jumo 210 have had an intercooler, ditto for Jumo 211 before the J.
 
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Deleted member 1487

I know this will sound cocky, but English language literature is often in collision with German literature, and I prefer to use the later for German hardware. The German word 'Druck' = 'pressure' in English in this case (can also mean print, strain, force). Also please see here, all Ju 88A bomber versions are listed as having 7500 m service ceiling ('Dienstgipfelhöhe') without bombs, be it with Jumo B, G or J engines.

BTW - the 'Powering the Luftwaffe' book at pg. 49 says that Jumo 213F have had a 3-stage supercharger - nope, not the case.
I was incorrect in stating that the pressurized cooling system was related to service ceiling, it actually limits what power the engine could operate at, so even those engines without pressurized cooling systems could operate at higher altitudes, they just would run at lower power due to the cooling system losing effectiveness as pressure dropped.

As to the translation, yes I know that druck means pressure, I can read German, the thing is every other source I've been able to find about the Jumo 211 has said that the pressurized cooling system only appeared with late models of the Jumo 211 and part of the developmental path that led to the 213 was the result of the development of pressurized cooling after 1940. The cooling system of the early 211s did have a pumping system to circulate it, perhaps that is what the reference to the closed pressure system meant or perhaps that particular book in German is simply incorrect.

L88 was a different engine, there was plenty of different engines. I've never claimed that any Jumo 210 have had an intercooler, ditto for Jumo 211 before the J.
So why did you bring it up?
 

Deleted member 1487

Check it out (T 60FF is a 60rd drum, T 90FF is a 90rd drum):
According to that the filled 90 round drum adds 10kg of weight over the 60 round version even with the limited gain in overall size. Can that still fit in the Bf109 wing without impacting performance and was it ever?

Those schematics are for the still-born Do-317 (4 tons max internal), not for Do-217 (3 tons max internal). Note the square-ish cross section, vs. triangle-ish of the Do 217. Also covered here.
Yes, I have other pictures:
do217 bomb bay.jpg

bomb bay 2.jpg


The problem with the load of even the early Do217s is that it had limited attachment points for bombs, so even with smaller bombs it could only carry a fixed amount. That's not a problem necessarily if you're only using it to take large bombs, but for lighter loads it is no better than the He111 and in fact quite a bit worse due to the overall size and cost of the aircraft, plus need to use more powerful engines and more fuel to run it. It is a specialized bomber for big bombs without redesign.
It was bigger, slower, and required more powerful engines not available in 1940 unless the DB603 was ready due to a POD and even then it would be a lower powered DB603 than the one of OTL 1942 with the compromised reliability.

BMW 801A and 801G were not the same engines, 801G was the sibling of 801D, 801A was even less powerful than 801C.
We can try bombing up both of the aircraft with 2000 kg of bombs, install 801D/801G on Do 217 and then measure speed.
Are we talking about the original clean design of the Ju88 or the dive bombing, external bomb rack Ju88?

The closest comparison we probably can get is the Do-217N with DB603 engines and 1750hp each and the Ju88G6 with Jumo 213 engines rated at 1750hp each. Both night fighters with the draggy radar gear and flame dampeners limiting any thrust gains.
http://www.airpages.ru/eng/lw/ju88g.shtml
Maximum speed km/h 538
at altitude, m - 6000

http://www.airpages.ru/eng/lw/do217n.shtml
Maximum speed, km/h at altitude 515
m 6000


Probably it was indeed undepowered. Note the max speed of 523 km/h per Brown.
Right, the M series with DB603A engines with 1750hp for take off and more power and less drag at altitude than the BMW801G engines.

I want operational/strategic Ju-88 all the time. He 111 demands good fighter cover over England, the, hopefully, fast Ju 88 is less dependant.
They the Ju88 would be the OTL diving, external bomb rack model ready in 1940 that is slower than the original design. If you want something that is set up for bigger bombs internally and with a raised wing you want the Do217, but that wasn't ready in 1940 and would have required more powerful engines that were available historically. Even an early DB603 engine would be lower powered than the aircraft would require and the OTL 1942 model.
Now you could of course just add the DB601 engines (Jumo 211s would also probably work) to the Do17 and made a Do215 bomber:
https://en.wikipedia.org/wiki/Dornier_Do_215
It could take 250kg or 500kg bombs internally.
Light and cheap and already in production, so you could spam them out. Faster than the He111 by a considerable margin too. You could probably even clean up it's wings and nose to make a more aerodynamic aircraft if you really wanted.

If we exchange each Bf 110 made in 1939-40 for two Bf 109s, it is 1160x2=2320 extra 109s. Granted, we will not have much of use for the 109s produced in last 3 months, so it is perhaps 2000 extra before October 1940.
Production of Bf 109s in 1939-40 was 2100+ examples. Decreasing that number for 3 last months production = ~1800.
All said, going all out for Bf 109s more than doubles up their numbers during our time frame of interest. This is before we account for economies of scale.
Training up that many more pilots would mean a reduction in quality, though perhaps quantity has a quality all it's own in this case, especially if they could keep up with the wooden drop tank demands.
 
I was incorrect in stating that the pressurized cooling system was related to service ceiling, it actually limits what power the engine could operate at, so even those engines without pressurized cooling systems could operate at higher altitudes, they just would run at lower power due to the cooling system losing effectiveness as pressure dropped.

As to the translation, yes I know that druck means pressure, I can read German, the thing is every other source I've been able to find about the Jumo 211 has said that the pressurized cooling system only appeared with late models of the Jumo 211 and part of the developmental path that led to the 213 was the result of the development of pressurized cooling after 1940. The cooling system of the early 211s did have a pumping system to circulate it, perhaps that is what the reference to the closed pressure system meant or perhaps that particular book in German is simply incorrect.

All liquid-cooled engines have had pumps for coolant - V-1710, Merlin, DB engines, you name it.
The cooling system on Jumo 211F and later worked at much greater pressures, that will raise efficiency of cooling system, thus allowing for greater power without much increasing the size of radiator, if any increase.

So why did you bring it up?

Sorry, I will ask for permission next time.
 

Deleted member 1487

All liquid-cooled engines have had pumps for coolant - V-1710, Merlin, DB engines, you name it.
The cooling system on Jumo 211F and later worked at much greater pressures, that will raise efficiency of cooling system, thus allowing for greater power without much increasing the size of radiator, if any increase.
So you are admitting that there was a change to the cooling system that upgraded performance?

Sorry, I will ask for permission next time.
I'm simply asking what relevance to the discussion it had.
 
According to that the filled 90 round drum adds 10kg of weight over the 60 round version even with the limited gain in overall size. Can that still fit in the Bf109 wing without impacting performance and was it ever?

You know that I'm affirmative with Bf 109 with 90 rd drums for MG FFMs.

Yes, I have other pictures:

The problem with the load of even the early Do217s is that it had limited attachment points for bombs, so even with smaller bombs it could only carry a fixed amount. That's not a problem necessarily if you're only using it to take large bombs, but for lighter loads it is no better than the He111 and in fact quite a bit worse due to the overall size and cost of the aircraft, plus need to use more powerful engines and more fuel to run it. It is a specialized bomber for big bombs without redesign.
It was bigger, slower, and required more powerful engines not available in 1940 unless the DB603 was ready due to a POD and even then it would be a lower powered DB603 than the one of OTL 1942 with the compromised reliability.

This is why I want the Ju 88 with a good bomb bay - flies good/very good even on Jumo 211s, has very good payload capability, it can be available in time.


Are we talking about the original clean design of the Ju88 or the dive bombing, external bomb rack Ju88?
The closest comparison we probably can get is the Do-217N with DB603 engines and 1750hp each and the Ju88G6 with Jumo 213 engines rated at 1750hp each. Both night fighters with the draggy radar gear and flame dampeners limiting any thrust gains.
http://www.airpages.ru/eng/lw/ju88g.shtml
http://www.airpages.ru/eng/lw/do217n.shtml

The OTL Ju 88, with bomb racks and all, will be one slow bomber. Historically, the Ju 88A-4 (Jumo 211F or J) and just two drop tanks was well under 450 km/h.
The original Ju 88 (as streamlined as possible, no dive bombing requirement) + high wing and a proper bomb bay is what I prefer anyway.

They the Ju88 would be the OTL diving, external bomb rack model ready in 1940 that is slower than the original design. If you want something that is set up for bigger bombs internally and with a raised wing you want the Do217, but that wasn't ready in 1940 and would have required more powerful engines that were available historically. Even an early DB603 engine would be lower powered than the aircraft would require and the OTL 1942 model.
Now you could of course just add the DB601 engines (Jumo 211s would also probably work) to the Do17 and made a Do215 bomber:
https://en.wikipedia.org/wiki/Dornier_Do_215
It could take 250kg or 500kg bombs internally.
Light and cheap and already in production, so you could spam them out. Faster than the He111 by a considerable margin too. You could probably even clean up it's wings and nose to make a more aerodynamic aircraft if you really wanted.

I've always liked the Do-17, especially the early, streamlined versions. The Ju 88 (even with early engines) will let us haul bigger bomb+fuel load, though.

Training up that many more pilots would mean a reduction in quality, though perhaps quantity has a quality all it's own in this case, especially if they could keep up with the wooden drop tank demands.

One benefit of not having 2-engined fighter is that there is no additional tarining required for 2-engined A/C for fighter pilots.

So you are admitting that there was a change to the cooling system that upgraded performance?

Yes, there was a change.

I'm simply asking what relevance to the discussion it had.

Showing that Junkers/Jumo was producing high-altitude engines many years before Jumo 211 emerged. Open-circuit cooling system will not work at high altitudes, the fact Jumo will know 1st hand.
 
Looking at the period 1936-1940 can we imagine that the Germans had intelligence assets in GB comparable with the contemporary Russian "Red Orchestra"- or would this be considered ASB? It would certainly help the LW prepare for the BoB

In my opinion the most prominent single deciding factor in BoB was British ability to employ RADAR to direct defenders to the locations where they could intercept LW raids. -That and LW failure to apply sufficient force to overwhelm and continually suppress Chain Home from the outset of BoB. The technology existed (certainly by 1938) to equip aircraft with RADAR radiation homing autopilots for night missions, at low altitude except for pop-up pilot bailout close in, followed by a homing dive into target. With detectors blinded- and no small scale or mobile replacement RADARs yet available, Britain's major interceptor force multiplier would no longer prevent the bombers from getting through. (Chain Home mapped during clandestine flights by LZ-130 in 1939, but no real follow through.)

Quick comment on "evaporative" cooling as applied to a number of German, and a couple of British aircraft- Unlike Schneider Trophy racing aircraft which, beginning with US Navy Curtiss, used water circulating within thin, large area heat transfer sheets conforming to -and covering virtually all wing surfaces (and later pontoons as well). The water did not change phase so no steam was involved and the temperature difference between coolant and ambient was small. Engine coolant was not pressurized, as the surface heat exchangers could not survive any substantial delta P.

The British flirtation with steam cooled engines in the early thirties generally required the steam to be evolved within the engine (somewhat like a boiler), and expanded thru an orifice into a lower pressure (radiator like) heat exchanger. Condensate was to be pumped back into the engine but problems with just where the steam and water were located during maneuvers discouraged the British and led to a further iteration. Here the engine cooling jacket was pressurized heavily, tho some nucleate boiling was permitted at engine hot-spots (steam reabsorbed into coolant as it circulated). Superheated water, again thru an expansion orifice evaporated into steam, and flowed thru spanwise pipes lagged to the interior of the wing skins. Typically these wing skins are thicker than necessary to increase conductivity to the free stream. The surface inside the tubes is much less than in the first example, but the heat transfer coefficient of the condensing steam is very much greater, producing a higher wing surface temperature, thus requiring less area exposed to airflow.

All this as background, the location along the flowpath and at what temperature the wing surface rejects heat determines the drag penalty, which could be substantial. While the increase in drag of heated wings was usually lower than the relatively simple radiator installations of the thirties, copies of "Cooling of Aircraft Engines With special reference to ethylene glycol radiators enclosed in ducts" By F W Meredith, could be had, after August 1935 at His Majesty's Stationary Service for less than a pound. Plenty of time for the He100 or even a fast P-40.

Dynasoar
 
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Plenty of time for the He100 or even a fast P-40.
Reportedly Don Berlin, chief Designer at Curtiss till he moved over to GM in 1941, was unhappy with the Model 81 (thru P-40C) was almost made a different aircraft in the Model 87, the P-40D
with a larger than needed Chin Radiator for Oil and Glycol, and overly strengthened the already robust airframe and thicker skins. More weight than what the slightly improved Allison could output, so in many way, lower performing than the previous aircraft

The last project he seemed to actually work on, was the dud P-46, that went back to an underwing scoop like the first XP-40 tried, but with some attempt at using the Meredith effect. NAA did purchase that info and wing tunnel data for what would become the Mustang
 
Reportedly Don Berlin, chief Designer at Curtiss till he moved over to GM in 1941, was unhappy with the Model 81 (thru P-40C) was almost made a different aircraft in the Model 87, the P-40D
with a larger than needed Chin Radiator for Oil and Glycol, and overly strengthened the already robust airframe and thicker skins. More weight than what the slightly improved Allison could output, so in many way, lower performing than the previous aircraft

The last project he seemed to actually work on, was the dud P-46, that went back to an underwing scoop like the first XP-40 tried, but with some attempt at using the Meredith effect. NAA did purchase that info and wing tunnel data for what would become the Mustang

Two ironies there. The P-40 /A/B/C was about as fast as much smaller Bf 109E on comparable horsepower, despite the 109E being much smaller and lighter, while XP-46 (prototype) was not faster than early P-40 (service-worthy).
But yes, Allison was too much late with introduction of considerably improved V-1710s vs. what RR and DB did with Merlin and DB 601/605 respectively.
 
MW 50
https://en.wikipedia.org/wiki/MW_50

Mw50 should be possible in 1940.
The biggest problem the Luftwaffe had was poor organisation.
The book below gives a detailed analysis of the problems of the Luftwaffe.
Strategy for Defeat
The Luftwaffe
1933-1945

by
WILLIAMSON MURRAY
https://www.ibiblio.org/hyperwar/AAF/AAF-Luftwaffe/

Short term best thing the Luftwaffe could do in 1940 is not to fight the battle of Britain, lots of attrition and no real gain to be made.
 
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Deleted member 1487

You know that I'm affirmative with Bf 109 with 90 rd drums for MG FFMs.
I know that you prefer it, but the question was was it possible given the large weight increase and space limitations? Historically the only reference I can find to it being used in a single engine fighter was the FW190 and that required wing bulges to get it to fit.

This is why I want the Ju 88 with a good bomb bay - flies good/very good even on Jumo 211s, has very good payload capability, it can be available in time.
That's the problem, the bigger the bomb bay the heavier the aircraft, the slower it is, the more defensive guns and escorts it needs. Since we are limited to the engines available at the time there is a serious limit on horsepower, which means you need to either have a smaller, faster, lower payload aircraft or a heavier, bigger, slower aircraft that needs more defensive guns and an escort like the HE111. The Do217 project was only started in 1938 and even with an early DB603 engine it won't be ready until 1941 at the absolute earliest. The Ju88 redesigned in 1936, your start date, means major delays in the project before it even flies, which limits any number available in 1940, perhaps delaying it worse than IOTL and creating an unknown differences in aircraft speed or aerodynamics, or handling. If you are just trying to create a 'middle weight' Do217 then you're SOL because then it becomes too heavy and has a highly limited capacity due to how many internal attachment points it can actually have. It has to be smaller than the OTL Do217 so that it isn't seriously under powered, which then limits what capacity it can have. You can then probably only have two 500kg bombs at a time or 2x 250kg (again limited by attachment points in the bomb bay), or 10-20x 50kg. And you'd have an aircraft that is effectively the Do215 in capacity, but bigger and slower.

The OTL Ju 88, with bomb racks and all, will be one slow bomber. Historically, the Ju 88A-4 (Jumo 211F or J) and just two drop tanks was well under 450 km/h.
The original Ju 88 (as streamlined as possible, no dive bombing requirement) + high wing and a proper bomb bay is what I prefer anyway.
So you want the Do215 with cleaned up wings and nose. You have to limit carrying capacity due to the need for speed and already the Do215 has the ability to take the bigger bombs you wanted while still having speeds over 450km/h. The only issue is the total payload, but it has the ability to take as much as the DH Mosquito did, including having bigger bombs, while still being the same weight and probably would be as fast as that was with engines as powerful. With some aerodynamic cleanups, like improved wing profile and a nose design like the DH Mosquito or early Ju88 it would probably even gain in speed over the OTL version. Plus we know it could have been a decent night fighter and recon aircraft.

I've always liked the Do-17, especially the early, streamlined versions. The Ju 88 (even with early engines) will let us haul bigger bomb+fuel load, though.
And the HE111 lets us haul being fuel and bomb loads still. You can either have speed and lightness or payload and high weight. If you're going to be carrying bigger bombs in the 250-500kg range, then you're probably just by internal capacity only going to be able to take 1000kg total of them due to their girth and the limited number of internal attachment points, which the Do-215 already did. If you want heavier internal capacity you already have the He111, which as enough defensive armament for 1939-40 and really any bomber is going to have to be escorted anyway. We could just have the Luftwaffe focus on aerodynamic cleanups for the Do-215 and giving it better engines, which would increase the range and speed substantially, effectively giving the Luftwaffe a 1940 DH Mosquito; we could even have it use the wooden drop tanks to enhance range, using them for the first hour or so of flight and dumping them before getting into enemy air space.

One benefit of not having 2-engined fighter is that there is no additional tarining required for 2-engined A/C for fighter pilots.
Sure, but you still need special training for the Bf109 to be able to properly handle it.

Showing that Junkers/Jumo was producing high-altitude engines many years before Jumo 211 emerged. Open-circuit cooling system will not work at high altitudes, the fact Jumo will know 1st hand.
Intercoolers aren't about altitude ability though, they're about the ability to run the engine at a higher speed without overheating, increasing power. The non-pressurized cooling systems won't work at a well at altitude due to the pressure drop impacting the ability for the water coolants to absorb the heat and circulate effectively. They'll work to a point, but will require the engines run at lower speeds.

MW 50
https://en.wikipedia.org/wiki/MW_50

Mw50 should be possible in 1940.
Yeah about that:
https://en.wikipedia.org/wiki/MW_50
Fittings for MW 50 first appeared on the BMW 801D in 1942, but it never went into production for this engine because the cylinder heads developed micro-cracks when MW 50 was used.
Plus it required a lot more complexity due to additional plumbing and a tank for the mix:
lcnd.jpg


The Germans had some issues with their engine boosting efforts in 1940 as well, having developed the DB601N around the 100 octane C3 fuel, anticipating 1400hp with it, but at full power the engine started falling apart and they had to restrict it to about 1200hp max.
http://kurfurst.org/Engine/DB60x/DB601_datasheets_N.html
Have them fix that issue and they'd be able to compete with RAF WEP without having to resort to the complexity and issues related to using MW50.

The biggest problem the Luftwaffe had was poor organisation.
The book below gives a detailed analysis of the problems of the Luftwaffe.
Strategy for Defeat
The Luftwaffe
1933-1945

by
WILLIAMSON MURRAY
https://www.ibiblio.org/hyperwar/AAF/AAF-Luftwaffe/

Short term best thing the Luftwaffe could do in 1940 is not to fight the battle of Britain, lots of attrition and no real gain to be made.
Murray's book is good, but there are better ones out there for the problems of the Luftwaffe, including a German one about structural flaws in the general staff (Die deutsche Luftwaffenführung 1935–1945. Führungsprobleme. Spitzengliederung. Generalstabsausbildung.)

Also there was Stephen Bungay's book "Most Dangerous Enemy" which lays out a solid strategy for defeating the RAF in 1940, but requires hindsight to some degree, namely in the use of the Bf110 as fighter bombers. Actually defeating the RAF in 1940 might help create room to negotiate an end to the war, but that is of course highly speculative and would require following Bungay's plan to the letter and it going to plan (it involves commando raids on the radar stations and well as earlier and more bombing of the fighter and engine factories to cut the replacement flow of RAF fighters...the Germans actually knew where they were and bombed a number of them IOTL relatively late in the campaign and without follow up in part due to underestimating the output of the facilities).
 
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NoMommsen

Donor
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Do you have a source on that? This is the first I've heard about it being delayed for that reason. I know the Germans did try that, but it seems like a bizarre reason to delay the introduction of the weapon system over.

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The documents on this site - though incomplete - hint in that direction.
 
Put simply... a better Luftwaffe for 1940 is one that has reserves of aircraft. The crews were there in abundance, well pilots at least, but not the aircraft. Imagine Eagle Day a month earlier or maintaining 900+ Bf109s in the frontline in early September just as Fighter Command is at its lowest ebb.
 
You've outlined the problem, but it's not about stuff.

It's about systems.

New pilots are important. Command and control are important. Systems for analysing operational results are important.

Gear ? Thats not important.

Yup. Six pages of irrelevant technical minutiae, just angels dancing on pinheads. The Luftwaffe had the tools it needed, but it didn't know how to use them, or that its methods of finding out what was working and what wasn't were worthless.

Sorting out the Luftwaffe intel will give far greater results than some drop tanks, a different fighter type or using 110s in a ground attack role. In the last case, use of 110s like that would probably be abandoned because of prohibitive losses without understanding the impact on FC.
 
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I know that you prefer it, but the question was was it possible given the large weight increase and space limitations? Historically the only reference I can find to it being used in a single engine fighter was the FW190 and that required wing bulges to get it to fit.

2 x 10 kg is large weight increase? The wing bulges were used already on Fw-190A-1/A-2, that used 60rd drum, as well as on the Bf 109E-3 to E-7.
60 rd drum height and width was within a few mm vs. the 90 rd drum.


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And you'd have an aircraft that is effectively the Do215 in capacity, but bigger and slower.
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... If you want heavier internal capacity you already have the He111, which as enough defensive armament for 1939-40 and really any bomber is going to have to be escorted anyway. We could just have the Luftwaffe focus on aerodynamic cleanups for the Do-215 and giving it better engines, which would increase the range and speed substantially, effectively giving the Luftwaffe a 1940 DH Mosquito...

No, not me. I'd have Ju-88 with, you guessed it, normal bomb bay. He 111 stays as-is - a capable bomt truck, that requires fighter escort to get the job done.

Sure, but you still need special training for the Bf109 to be able to properly handle it.

Not as much as for a twin engined A/C.

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The non-pressurized cooling systems won't work at a well at altitude due to the pressure drop impacting the ability for the water coolants to absorb the heat and circulate effectively. They'll work to a point, but will require the engines run at lower speeds.

For maximum continuous in high S/C gear, the Jumo 211B was to be run at 2100 rpm and up to 0.90 ata under 4.5 km, and at 2300 rpm and up to 1.05 ata above 4.5 km. That is 200 rpm more, not less at higher altitudes.

The Germans had some issues with their engine boosting efforts in 1940 as well, having developed the DB601N around the 100 octane C3 fuel, anticipating 1400hp with it, but at full power the engine started falling apart and they had to restrict it to about 1200hp max.
http://kurfurst.org/Engine/DB60x/DB601_datasheets_N.html
Have them fix that issue and they'd be able to compete with RAF WEP without having to resort to the complexity and issues related to using MW50.

Germans/DB shot themselves in foot when increasing compression ratio when going from DB 601A to 601N - from 6.9:1 to 8.2:1. For comparison, Merlin was at 6:1, V-1710 at 6.65:1. Greater compression ratio vastly incresses stress the engine must endure, for a small gain in power.
DB reduced CR for DB 601E to 7.2:1.
 
Two ironies there. The P-40 /A/B/C was about as fast as much smaller Bf 109E on comparable horsepower, despite the 109E being much smaller and lighter, while XP-46 (prototype) was not faster than early P-40 (service-worthy).
But yes, Allison was too much late with introduction of considerably improved V-1710s vs. what RR and DB did with Merlin and DB 601/605 respectively.

XP-40, before NACA testing 5417 pounds,1060HP 317MPH, hardly better than the P-36
xp40-18.jpg
After rework, 366mph
Curtiss-XP-40-in-NACA-wind-tunnel-Langley-Field-24-April-1939.jpg
lumps and bumps removed, gycol radiator moved up with the oil cooler
P-40B Warhawk empty weight 5,590 pounds, 1150 HP, 352mph, more guns and armor
screen-shot-2018-12-15-at-13-55-47
more changes to radiator

Last, the poor XP-46. 5,625 pounds empty 355mph on the same Allison as the P-40C,
curtiss_p-46.jpg
no way it was going to hit the designed 400mph on that amount of power with two .50s and eight .30s, fully self sealing tanks and armor, what was needed for combat in 1941.

For a clean sheet design, it just had no advantage over the then marginal P-40D already in production. The wind tunnel data and design info was then sold off to NAA, and they refined what was there with their own designers to become the Mustang. Much better deal for all the Allies, than had they just become a sub-contractor to build more P-40s for the British
 
Some comments on issues already raised:

Unpressurized coolant boiling temperature decreases about 1.72 degrees F per thousand feet of altitude. A pure water cooled, but unpressurized system at 18,000 feet, would boil at an indicated 180F. Temperature lapse at altitude would increase the heat rejection to ambient from the the lower temperature coolant, but the engine would still see a 180F internal coolant temperature. Above that temperature coolant would vaporize within the engine and, as steam, be unable to extract enough heat to prevent boil-over and coolant loss.

How does adding heat to airflow over a (lifting) wing increase drag? Imagine the processes inside a ramjet, or within a Meredith cooling duct. Air enters a divergent duct (diffuser) where it slows and increases in pressure. Heat is added- by combustion or rejection from a radiator, then the air, much increased in volume and velocity by thermal expansion, enters a convergent nozzle. Here the flow is accelerated and the added heat is converted to kinetic energy which is thrust for the ramjet or drag reduction for the Meredith duct.

With a wing, the flow conditions are reversed- at the leading edge to the point of maximum thickness, flow is accelerated and consequently reduced in pressure. There is no constant region before the divergence to the trailing edge where flow velocity is decelerated. The processes are the reverse of the thrust producing examples. Visualization might be helped by imagining a wing airfoil cross section wrapped around a central axis- forming a classic Venturi, and the opposite cross section sequence of a ramjet. Expansion of flow anywhere in the Venturi will increase pressure drop which corresponds to aerodynamic drag.

I'm surprised by the comparison photos of the evolving Curtiss P-40. I would have bet that the first version with the relatively clean nose and belly radiator would have been the fastest. The gun fairings might have screwed up prop flow and could have benefited from some tuft testing. The radiator duct appeared like a short, simplistic fairing (tho in the right place) rather than anything incorporating Meredith's teachings.

If there is a report dealing with these mods, I'd love to see it.
 
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