What if the Luftwaffe technological gambles worked out?

[kool kitty89]

Airliners designed for "prestige", like the Fw 200, first land based airliner designed for transatlantic crossings and flying with a subsidized airline are probably not the best choices for an all round or military transport.

I was mostly suggesting its use early on with emphasis on displacing it with the Ju-252 ASAP. (and, preferably, something closer to the DC-3)

The Fw 200 also at least seems favorable to focus on over the Ju 290 and in some respects a proper He 177. (far more over the existing He 177, but still some advantages in time to service and perhaps cost compared to a 4-engine He-177 -especially in terms of logistics of volume production and spare parts) Probably not good as a heavy bomber, more so just long range/endurance patrol, bomber, and transport. (I somewhat doubt it would convert efficiently to a heavy bomber remotely as capable as a ... rational 4-engine He 177, but aside from that you have the Do 217 pulling heavy short/medium range payloads)

A properly structurally corrected Fw 200 as you pointed out before, would be the target there.

The canceled Fw 206 seems to have been targeting exactly that sort of design, but given how early development was halted, it's really hard to tell how it might have worked out. Either way it was late. Something like that should have been flying pre-war, but even so it seems like a more worthwhile target than a good many of the transport designs that were still only on paper (if that) at the outbreak of the war.

The He 111 comments were more pointed towards possible modification too. But fuselage redesign/stretching isn't always faster/simpler than 'whole new aircraft.' (probably much more feasible than ideas like the He-111Z, at least) Modifications like that should have started pre-war though.

I am not holding out the C-47 as the ideal military transport but with the basic airplane flying over 3 years before the attack on Poland it should have been obvious that the Ju 52 left something to be desired.

Intending the Ju 52 as anything more than an interim aircraft to be replaced as soon as possible (with plans focusing on such pre-war) is rather strange. Aside, of course, from using it as a specialty rough-field operating design. (but the DC-3/C-47 managed well or better in most similar conditions as well)

One often overlooked transport was the Siebel Si204, a twin that was relatively fast for it's time with a range of 875 miles and a max. load of 3,600 pounds. Could be crewed by either one or two personnel and used non-essential Argus As411 engines.

I almost mentioned that aircraft earlier. I had it in mind when I brought up the Go 146 (given it was a competitor to the Fh 104 the Si 204 was based on). Unless I'm mistaken, the Go 146 was also wooden, so material resource advantage there on top of using small Hirth/Argus engines. I was imagining the Go 146 expanded into something closer to the Si 204.

And those engines/construction materials in mind, as well as the issue of airliner passenger capacity, I'm also reminded of the DH.91 Albatross. Gotha might not have been DeHavilland (or have access to the same types of wood),but a transport with nearly DC-3 passenger capacity using 4 AS-410/411(or HM512) class engines and 1000+ mile range (let alone one made of wood) is still interesting.

 

[GrauGeist]

I almost mentioned that aircraft earlier. I had it in mind when I brought up the Go 146 (given it was a competitor to the Fh 104 the Si 204 was based on). Unless I'm mistaken, the Go 146 was also wooden, so material resource advantage there on top of using small Hirth/Argus engines. I was imagining the Go 146 expanded into something closer to the Si 204.

And those engines/construction materials in mind, as well as the issue of airliner passenger capacity, I'm also reminded of the DH.91 Albatross. Gotha might not have been DeHavilland (or have access to the same types of wood),but a transport with nearly DC-3 passenger capacity using 4 AS-410/411(or HM512) class engines and 1000+ mile range (let alone one made of wood) is still interesting.

Imagine if they had ceased (or seriously cut back) on the Ju52/3m production and focused instead, on the Si204. The materials historically allocated for the Ju52 would have then been available for the Si204 production line. As it is, they only produced about 1,000 Si204 units as opposed to about 5,415 (+/-) Ju52 airframes.

The Ju52 certainly had it's place in history and proved to be a sturdy aircraft, but scaling back it's production after the Si204 was available would have certainly freed up resources.

This is not to say that the Si204 had a better survivability than the Ju52, as was shown during the airlift at Stalingrad, where the majority of Si204 (trainers and transports) were employed and a good number of them fell victim to Soviet interceptors.

 

[parsifal]

something I forgot to mention earlier as well. Not highly known, but the Ju52 was mostly used as a primary bomber trainer by the LW, with its pilots being mostly the instructors used in training. The Ju52 was sometimes diverted to airlift operation, when their losses were heavy (and they usually were), their supply of pilots and other aircrew for the bomber arm took a dive. Ive read that the decision to wind down strike aircraft production was in large measure forced on the germans because they could no longer provide specialist training for their strike aircraft.

So its always worth remembering that the Ju52 replacement had to fulfil more than one role

 

[Shortround6]

True but since Lockheed 14s were turned into Hudsons, Lockheed 18s turned into Venturas, DC-2s (with more modifications) turned into B-18s, and DC-3 wings, landing gear and other parts turned into the B-23, a "bomber trainer" variant of what replacement for the Ju 52 doesn't seem like a such a stretch.

Not to mention that using a 3 engine aircraft as a "bomber trainer" seems a bit wasteful. The US and the British managed to do a fair amount of bomber crew training with small twin engine aircraft like Ansons and Beech 18s (AT-7,AT-11).

Bristol Bombay and Handley Page Harrow were not used as trainers very much (more valuable as transports) but if more were available there was no reason they couldn't have been.

Different trainers were not going to change the outcome of the war but different airframes for existing engines are an easier "solution" or answer for some of the Luftwaffe problems than "new" engines like diesels. The JU 52 was a fuel hog for what you got out of it. Wither it is ton/miles of cargo transport or hours of crew instruction per 100 gallons used.

 

[kool kitty89]

True but since Lockheed 14s were turned into Hudsons, Lockheed 18s turned into Venturas, DC-2s (with more modifications) turned into B-18s, and DC-3 wings, landing gear and other parts turned into the B-23, a "bomber trainer" variant of what replacement for the Ju 52 doesn't seem like a such a stretch.

Converting more He-111s to dual control trainers would seem a reasonable option there too. (beyond smaller/lighter aircraft for general twin-engine training)

Not to mention that using a 3 engine aircraft as a "bomber trainer" seems a bit wasteful. The US and the British managed to do a fair amount of bomber crew training with small twin engine aircraft like Ansons and Beech 18s (AT-7,AT-11).

Yes, and Germany had the likes of the Fw 56 and Si 204 (and Fh 104). And then there's the Go 146, had it gone into production. (mostly interesting given the wooden construction)

Hmm, something along the lines of the DH.91 would also have been attractive as a 4-engine trainer short of using larger 4-engine aircraft.
Edit: perhaps the He 116 would fit well in that role?

The Ju-52's tri-engine design might sill have been useful for Ju-252 training, though, but you still don't need a ton of Ju 52s to fill its limited useful roles.

 

[nuuumannn]

The issues the LW needed to get to were a better supply of pilots and fuel. Better technologies are nice to have, but make very little difference to the battle problem facing the Germans for most of the war.

Yep, I agree. For all the technologically advanced equipment the Germans put into service there were as many that were duds that were unsuccessful, on which resources were wasted (in hindsight). It wasn't superior technology, or lack of it that lost the Germans the war, but managerial incompetence. Besides, had the Germans introduced more novel technologies, perhaps earlier and in larger numbers than they did, that is if they were able to, then you can guarantee the Allies wouldn't have sat back and done nothing.

This is the counter argument to all the German 'superior technology' debates that crop up from time to time here; firstly, their technological superiority wasn't as 'superior' as many like to believe, as the Allies were often working on the same ideas and had hardware available simultaneously, but were busying themselves with running a war and the priorities that that entailed, and secondly, any measure the Germans were likely to take, the Allies would prepare a counter-measure. This is the nature of warfare and while a minor lead in technology might have been achieved that might have given the Germans a bit of breathing space (the A-4 Rocket for example), the Allies could out produce anything the Germans, and indeed all the Axis powers were capable of, so the end result would have been the same, as others here have stated.

 

[nuuumannn]

Oops, double post - damn slow ass dinosaur powered New Zealand internet.

 

[GrauGeist]

Oops, double post - damn slow ass dinosaur powered New Zealand internet.

It's been happening to everyone all evening...freakin' server is acting up again

 

[kool kitty89]

Yep, I agree. For all the technologically advanced equipment the Germans put into service there were as many that were duds that were unsuccessful, on which resources were wasted (in hindsight). It wasn't superior technology, or lack of it that lost the Germans the war, but managerial incompetence. Besides, had the Germans introduced more novel technologies, perhaps earlier and in larger numbers than they did, that is if they were able to, then you can guarantee the Allies wouldn't have sat back and done nothing.

Poor allocation of resources (logistical) issues and a fair number of poor/odd decisions and mess of bureaucratic issues plagued wartime Germany. That includes engineering and manufacturing resources, and supporting unrealistic projects with unrealistic goals ... or mediocre projects that seem to have some sort of political edge.

I lot of time and resources were wasted on inferior designs, but also on pie in the sky, impractical, extravagant, inefficient designs that weren't strategically or tactically relevant. The Americans and Russians had advantages in terms of sheer raw resources, but the Americans and British also had advantages in logistical management in terms of overall serviceability. (in terms of building, fielding, and maintaining useful equipment)

The Germans were oddly conservative at times, and oddly radical at other times in pretty inefficient and contradictory ways. Compare that to the pragmatism and rationalization used for British manufacturing and engineering with strict limits placed on material production and development. They took a fairly conservative direction in this regard, but they were at least more consistent about that than the Germans. (look at British aircraft engine development compared to german, even taking the larger number of german firms in play, the sheer focus on most war-critical engine types -and similar focus on designing aircraft around those engines- was far higher in the UK with the likes of the Hercules and Merlin getting priority development, many less critical designs being canceled outright, and relatively little hinging on the success of the remaining lower priority high power engines like the Centaurus, Griffin, and Saber -and even then being more akin to the BMW 802, DB-603, and Jumo 213, at least in some respects -the Griffin and 603 probably being the most comperable)

In any case, the Germans had tons of room for improving efficient, practical, pragmatic allocation of resources of all sorts (again that includes intellectual/engineering resources) and plenty of room for being more conservative in some useful areas without even necessarily going as far as the British. (some of the american practices are also relevant, but their vast advantages in material resources skews comparisons somewhat)

Though I wonder, if there'd been similar heavy focus on the Jumo 211 and DB 601/605 as there bad been the Merlin, might adoption of more powerful superchargers and water injection have developed sooner? (having the DB-601 reach AM/ASM level performance earlier and/or bringing the Jumo 211 up to roughly similar performance would have been very useful and perhaps a more attractive trade-off than diverting resources to DB-603 and Jumo 213 development) Still, resources being poured into considerably more risky/farsighted projects would make more sense to cut back on. (and the Jumo 213 and DB-603 might have enough commonality with their smaller, lower powered counterparts that parallel development benefited both types anyway -the Jumo 213 more obviously so given the sheer design commonality)


And that's not even getting into the specific issues of offensive vs defensive weapon development. (or lack of planning regarding defensive technology in particular)


Superior technology + efficient development and utilization of that technology is something the Germans never really had over the allies, not consistently at least. (compared to the Russians, yes, but the British and Americans fairly comprehensively outperformed them as well, aside from perhaps gun design -the British and particularly Americans had quite a few areas of sheer technological superiority in as far as what was actually fielded)

 

[stona]

Much stems from the centralised organisation of the German aircraft industry.

The system originated with Milch (and Werner) in 1941.

This was the so called 'Ring Organisation' of the aircraft industry. For final aircraft assembly there were 13 firms chosen as central controller with a very large number of firms attached. The 13 were Junkers, Messerschmitt, Heinkel(Rostock), Focke-Wulf, Dornier, Arado, Siebel, Henschel, Bohm and Voss, Bucker, Fiesler, Gotha and Klemm. That's already too many and they 'controlled' another 40 companies(which I'm not about to name here!)
In the overall aviation industry there were 92 rings and 5,600 firms.

The Anglo-American systems, which lacked such overall central control, though there was more centralised planning than in peace time, were more efficient. Bang goes another racial stereotype.

Cheers

Steve

 

[Shortround6]

The British had the benefit of the better fuel when it came to engines. Since it can take 3-4 years to get a "new" engine into service (if you are lucky) you have to very sure of your future fuel supply. Modifications or adaptations of an existing design can be done quicker. But you can be stuck with some basic design features. The Merlin was fairly adaptable but then they didn't change a whole lot of the basic engine. They never changed cylinder size, or valve size or valve arrangement and they never changed the max rpm. Yes they changed superchargers and boost pressures almost as fast as a 3 card monte shuffle but the basic engine didn't change much.
The Hercules started as a way to get more power/economy from the same fuel (87 octane) but wasn't able to adapt as well to the much higher performance the better fuels allowed. Air cooled engines seldom could due to cooling limits and how much power you could put on a crankpin/crankshaft of a given size. Even in 1956 the Post war Hercules 811 was rated at 2220hp using 14.5lbs of boost and water injection from it's 38,7liters and 2235lbs compared to the 2455hp of a Griffon 57 using 25lbs boost and water injection from 36.7 liters and 2100lbs. Both engines using 100/130 fuel. Griffon has two speed supercharger and contra-rotating prop gear box adding weight but radiator and coolant not added in. A post war Hercules 800 series engine had a lot of changes from a wartime Hercules.
The Germans were forced to make a lot of basic changes to their engines as they developed them and some of their schemes were trying to make power while still using 87 octane fuel. Changing the RPM not only puts greater stress on the crank and reciprocating parts, it also changes the vibration pattern of the engine and can require new crankshafts and/or different counter weights or bearings or some other measure.
You can spend 3 years working on engine B to replace engine A only to have the fuel guys introduce Fuel Y to replace fuel X and allow engine A to make 90-95% of the power of engine B with only minor changes. Engine B isn't quite ready to go into production yet. What do you do?
And unless you know the overhaul lives of some of these engines you may be comparing apples and oranges. How much of the higher power was bought at the cost of reduced time between overhauls?
In some cases the higher power was also bought at the cost of higher initial cost, higher general maintenance, and higher overhaul cost. (more than 12 cylinders for a liquid cooled engine of more than 14-18 for a radial, or sleeve valves).

And for bombers you need to compare the max continuous power or 30 minute ratings, something other than 1-5 minute peak power ratings as it could take bombers 15-30 minutes to climb to operational heights (or longer depending on overload).

 

[kool kitty89]

The Germans were forced to make a lot of basic changes to their engines as they developed them and some of their schemes were trying to make power while still using 87 octane fuel. Changing the RPM not only puts greater stress on the crank and reciprocating parts, it also changes the vibration pattern of the engine and can require new crankshafts and/or different counter weights or bearings or some other measure.
You can spend 3 years working on engine B to replace engine A only to have the fuel guys introduce Fuel Y to replace fuel X and allow engine A to make 90-95% of the power of engine B with only minor changes. Engine B isn't quite ready to go into production yet. What do you do?

Wouldn't employing intercoolers/aftercoolers and/or water injection be solutions to the fuel and boost pressure issue without requiring more fundamental redesigns of the engines?

If not for the additional switch from roller bearings to plain bearings on the DB-605, there seemed to be plenty of reasonable options for increasing the existing DB-601's power short of increasing the displacement. (larger or 2-stage supercharger, intercooling, water injection) The Jumo-211 implemented an aftercooler, but still had a good deal of room for improving the basic supercharger as well as using water injection.

The performance jump from the DB-601E to the DB-605A was relatively small, the leap from Jumo 211J/N to 213A/B was considerably larger, as was the gain in weight. Not really an upgrade as much as a new engine more comparable to the DB-603 or Griffin.

Indeed, if not for the bearings (and possibly a few other detail changed made due to material shortages), there'd be a stronger argument for continuing production of the existing DB-601E and similar derivatives and focusing more on getting the DB-603 into production.

The BMW 801 D/G relied on C3 fuel to manage the performance they did without aftercooler or water injection, but that meant it getting priority for that limited fuel grade, depriving it from other engines while not employing other techniques to improve performance.


Good supercharger and intercooler design is what made the merlin adapt so well and lack of that is a big part of what made the V-1710 suffer (including turbo intercooler installation issues). If limited to the same 100 octane fuel being used during the Battle of Britain, the late war merlin models (and Griffin) may not have managed as much power, but they certainly still would have improved a great deal. (or they might have resorted to water injection and had similar power output)

 

[Shortround6]

The DB 601 was a 590kgA-0 dry weight engine, 1298lbs? I can't find a good weight for the 601E but a 605A was 710KG (1562lbs) so they beefed up some things somewhere.

Water injection was a useful but somewhat limited option. It works best when used below an engines rated altitude. For a DB601A-0 that was 3700meters. It can cool the intake charge, making it more dense above the rated altitude but that is only worth a few %. It is much more useful at lower altitudes. Things like the P-38 and P-47 excepted as their turbos could supply more air than the engine could use up to around 25-27,000ft in the later models. The 601A-1 used a different supercharger that had a critical altitude of 4500meters. The DB601E used a different supercharger (same as the 605A or???) and then they stuck on the supercharger from the 603. Please note however that bigger superchargers come at a price. At 2600rpm and the Kurzleistung rating the big supercharger cost the DB 605 35PS at sea level.

Intercoolers are elegant from an engineering standpoint. They allow more power and often less thermal stress and don't consume anything (and thus work at cruise settings) and air to air intercoolers have no moving parts (OK maybe a door/flap on the duct). However for the Germans the benefits are less than for the allies.
The intercooler removes some (not all) the heat from compressing the air. Since the Germans are compressing the less than the Allies, even 1.42 AtA is about 6lbs of boost, they have less heat to remove. You also have the drag of the intercooler. Cooling the intake air can vary from needing an equal amount of air going to the intercooler for a 40% efficient unit (lowers the the temp 40D/F per 100 degrees of intake temp) to 1.5 times for 50% to 2 times for 60% and 3 times the air for 70%, after that things get really poor.
Only Junkers thought the intercooler was worthwhile on a single stage (low boost) engine. Perhaps if the Americans/British had been limited to 87 octane fuel they may have changed their minds but on single stage engines it was probably best left to bomber engines. The intercooler gave the 211J about 140hp/PS at 16,5-17,000 ft at 2400rpm/1.25ata (climb rating) over the 211F.
Using an intercooler on a high boost engine gives much greater results. A DB605A was compressing the air just under 3 times at 1.42 ata at 5700 meters. A Merlin 61 was compressing the air 5.1 times at 23,500ft to get 12lbs of boost. Without the intercooler the Merlin 61 could not have used that level of boost without wrecking the engine even with 100/130 fuel. The Jumo 211J was compressing the air at 17,000ft about 2.41 times.

Please do not use car intercoolers as a comparison. Unless you are climbing Pike's Peak or racing in the alps if you compress the air even 1.5 times you are running over 22lbs of boost and operating at speeds close to the best climbing speed of an aircraft so the drag is way different. Drag of the intercooler at 320mph is 4 times what is at 160mph.

Both DB and Junkers chose to use large displacement slow turning engines of about the same weight as the smaller but higher revving Allison and Merlin to get the same power (roughly). Once paths were chosen it was hard to change paths.

Without better fuel the Germans had two basic choices. Larger engines or higher RPM as max cylinder pressure (boost) was limited by fuel.

The BMW 801 was limited by the same thing/s that limited ALL aircooled radial engines. The R-2800 engine used in the P-47M/N being the exception that proves the rule, not a standard that any other radial engine ever reached unless you count the Wright turbo compound and that required 3 power recovery turbines hooked to the crankshaft and adding about 550hp for take-off. BTW in the interest of longevity and safety the Turbos compounds left in use for firefighting service are limited to 53in (11.5lbs??) on 100/130 fuel and 2880hp at 2900rpm. On 100LL they are limited to 50In MAP and cannot use high blower (higher intake temperature at the same pressures.) These post war war engines had a lot of changes form even late war B-29 engines.

 

[Shortround6]

Continued.

The early JUmo 211s were also engines of 1300lbs or under dry weight. Both German engines were quite competitive with the early Merlin and Allison on a power to weight ratio. AND that is what matters to aircraft performance and designers.

It took quite a while for water injection to be adopted as a routine part of operations. Many very late war Military aircraft and postwar commercial aircraft being given "wet" ratings for take-off vs using water injection for emergency combat use only. I don'y know if was just accumulated experience or different materials or different maintenance procedures or a combination. There were fears of corrosion and/or oil problems with early use of water injection. A lot may depend on when in the mission/flight the water injection is used. If used for take-off you have the length of the flight to evaporate any water out of the intake system and oil (blow-by past the piston rings) Using it 20 minutes before landing and using low power settings while descending to land could leave trace amounts of water in the oil.
In combat you do what you have to do. Planing to use it on every flight is another story.

I don't know what the Germans did to the DB engines and to the Jumos as the they increased power. A lot of changes are important but subtle. And a lot affect service life at higher power settings. The Allison went though 4 different crankshafts after it was rated at 3000rpm. Only the last is visibly different than the first 3. ALL 3 of the early ones have the same RPM limit and all three will allow the engine to make the same power, at least for a short time. The Allison went through 3-4 crankshaft/counter weight/damper combinations to reach the 3000rpm limit. One of the last of the Pre-3000rpm cranks failed at 116 hours into a test.
The very first Allison crankshaft was rated a 2400rpm and had NO counter weights or much for dampers. Hispano-Suiza Y series engines that ran at 2400rpm had no counter weights. But vibration problems rise quickly, so quickly that solutions that work for small increases in RPM (going from 2400rpm to 2600rpm) fail to work when going to 2800rpm let alone 3000rpm.
Allison also changed the method they used for casting the engine blocks. Casting is more than just pouring molten material into a mold. Proper control of casting temperatures and cooling can affect grain structure an orientation and vastly change the strength of the same nominal material. Different casting techniques can affect how deep cooling fins on an air-cooled engine are and how thin and closely spaced. Good casting techniques can also result in a part coming out of the mold much closer to the finished dimensions and need much less time being finish machined to desired dimensions. Just because you can build a few prototypes doesn't mean you can manufacture something in mass at a low scrap rate and low cost.
There is an interesting table in Vees for Victory on page 408 comparing a 1918 Liberty aircraft engine to a 1943 Allison. aside from the obvious differences (400hp to 1425hp) the time between overhauls went for 50 hours to 500+ hours, the crankshaft weight dropped from 105lbs to 95lbs and yet the tensile strength of the crankshaft material only went from 135,000lbs to 140,000lbs. Differences in finishing ( shot peening and nitriding) and inspection (visual vs Magnetic) helping the counter weighting and effective vibration dampers ot allow both the higher power and longer life. details like this are often lacking in histories of other engines.
Going from the 2400rpm DB601 to the 2800rpm DB 605 is a lot more than just changing counter weights or adding a bit of weight here and there to the crankshaft. The forces involved acting on the crankshaft went up by about 36% and the vibration problems probably change dramatically.

 

[tomo pauk]

Many thanks for the above stuff

The DB 601 was a 590kgA-0 dry weight engine, 1298lbs? I can't find a good weight for the 601E but a 605A was 710KG (1562lbs) so they beefed up some things somewhere.

The 601E was at 660 kg dry; with accessories (fuel pump, ignition radio blockade, prop governing device, residual fuel oil, covering plates) was at 710 kg; with all of that plus with starter it was at 720-725kg. Per manual for the DB 601E/G, pg. 23-24. Download of manual (not sure whether it works for non-registred people there): link.

Water injection was a useful but somewhat limited option. It works best when used below an engines rated altitude. For a DB601A-0 that was 3700meters.
...
The 601A-1 used a different supercharger that had a critical altitude of 4500meters. The DB601E used a different supercharger (same as the 605A or???) and then they stuck on the supercharger from the 603.

The early DB 601A have had rated altitude at 4 km, later ones were at 4.5 km; both for 1020 PS. The DB 601Aa (a = ausland = intended for export; many LW aircraft carried it nevertheless) have had rated altitude of 3.7 km, but for power of 1100 PS.

Only Junkers thought the intercooler was worthwhile on a single stage (low boost) engine. Perhaps if the Americans/British had been limited to 87 octane fuel they may have changed their minds but on single stage engines it was probably best left to bomber engines. The intercooler gave the 211J about 140hp/PS at 16,5-17,000 ft at 2400rpm/1.25ata (climb rating) over the 211F.

Looks like it was not 140 PS at 16.5-17 kft - 1140 PS vs. 1060 PS (30-min power). The 211J was having ~140 PS advantage between ~10 kft and ~16 kft.

Going from the 2400rpm DB601 to the 2800rpm DB 605 is a lot more than just changing counter weights or adding a bit of weight here and there to the crankshaft. The forces involved acting on the crankshaft went up by about 36% and the vibration problems probably change dramatically.

The DB 601N was allowed for 2800 RPM already in late 1940, the DB 601A up to 2600 (2800 in mid 1941) rpm in same time (above rated height for both engines). Granted, the lower settings and take off ratings received no benefits of that.
link

added: the DB-605L (two-stage supercharger) used MW 50 both on 1.43 ata and 1.70 ata - the inter-cooler would've indeed come in handy?

 

[rinkol]

Converting more He-111s to dual control trainers would seem a reasonable option there too. (beyond smaller/lighter aircraft for general twin-engine training)


Yes, and Germany had the likes of the Fw 56 and Si 204 (and Fh 104). And then there's the Go 146, had it gone into production. (mostly interesting given the wooden construction)

Hmm, something along the lines of the DH.91 would also have been attractive as a 4-engine trainer short of using larger 4-engine aircraft.
Edit: perhaps the He 116 would fit well in that role?

The Ju-52's tri-engine design might sill have been useful for Ju-252 training, though, but you still don't need a ton of Ju 52s to fill its limited useful roles.

After JU 86 bomber production was cancelled, there was a scheme to use up stocks of parts to complete the planes for training purposes, but this seemingly sensible idea was quashed.

Another possibility would have been to build the SM 82 under license, perhaps with 3 Bramo 323 engines. This would have certainly provided a lot more capability than the Ju 52.

 

[kool kitty89]

The DB 601 was a 590kgA-0 dry weight engine, 1298lbs? I can't find a good weight for the 601E but a 605A was 710KG (1562lbs) so they beefed up some things somewhere.

Water injection was a useful but somewhat limited option. It works best when used below an engines rated altitude. For a DB601A-0 that was 3700meters. It can cool the intake charge, making it more dense above the rated altitude but that is only worth a few %. It is much more useful at lower altitudes. Things like the P-38 and P-47 excepted as their turbos could supply more air than the engine could use up to around 25-27,000ft in the later models. The 601A-1 used a different supercharger that had a critical altitude of 4500meters. The DB601E used a different supercharger (same as the 605A or???) and then they stuck on the supercharger from the 603. Please note however that bigger superchargers come at a price. At 2600rpm and the Kurzleistung rating the big supercharger cost the DB 605 35PS at sea level.

Intercoolers are elegant from an engineering standpoint. They allow more power and often less thermal stress and don't consume anything (and thus work at cruise settings) and air to air intercoolers have no moving parts (OK maybe a door/flap on the duct). However for the Germans the benefits are less than for the allies.
The intercooler removes some (not all) the heat from compressing the air. Since the Germans are compressing the less than the Allies, even 1.42 AtA is about 6lbs of boost, they have less heat to remove. You also have the drag of the intercooler. Cooling the intake air can vary from needing an equal amount of air going to the intercooler for a 40% efficient unit (lowers the the temp 40D/F per 100 degrees of intake temp) to 1.5 times for 50% to 2 times for 60% and 3 times the air for 70%, after that things get really poor.
Only Junkers thought the intercooler was worthwhile on a single stage (low boost) engine. Perhaps if the Americans/British had been limited to 87 octane fuel they may have changed their minds but on single stage engines it was probably best left to bomber engines. The intercooler gave the 211J about 140hp/PS at 16,5-17,000 ft at 2400rpm/1.25ata (climb rating) over the 211F

I was referring to both intercooling and water injection as technologies used to allow higher boost levels on lower octane fuels in the hypothetical context of German engines focusing more on supercharger boost performance and less on increasing RPM or swept volume.

That includes use of larger or higher speed superchargers to supply higher boost at higher rated altitudes. (thus making intercoolers more useful) That said, water injection would probably be more useful to introduce first with intercooling following later.

Jumo's use of aftercoolers on the 211 would have been more useful if higher altitude supercharger gearing was used (or used more frequently at least). Somewhat odd that that wasn't the case, but I suppose the demands for most aircraft using those engines preferred lower speed superchargers with a bit more power on take-off. (short of resorting to larger or 2-stage superchargers, I believe the existing single stage impellers were suitable for being pushed to higher speeds than most 211s used -I forget specifics, but this topic has come up before, at least briefly)

Both DB and Junkers chose to use large displacement slow turning engines of about the same weight as the smaller but higher revving Allison and Merlin to get the same power (roughly). Once paths were chosen it was hard to change paths.

I wasn't suggesting changing that, but rather avoiding some of the more difficult engineering issues you mentioned in regards to increases in RPM and further increases in volume with a greater emphasis on supercharger boosting. Granted, some components will need to be strengthened either way due to sheer power level increases. (keep RPM the same, and all that stress goes into torque)

Now, it may have been that the existing RPM increases (and other changes) to german engines were able to be achieved quickly enough that using engineering developments closer to the likes of the Merlin wouldn't have been much or any faster anyway, but that would totally nullify the points you were making regarding British engine development.

The BMW 801 was limited by the same thing/s that limited ALL aircooled radial engines. The R-2800 engine used in the P-47M/N being the exception that proves the rule, not a standard that any other radial engine ever reached

I was referring to the BMW 801's later models gaining more from boost increases and less from volumetric or RPM increases by relying on higher octane fuel WITHOUT intercooling or water injection (initially) more like allied engines were doing in general.

Additionally, I think the C-series 2-stage supercharged R-2800s are worth mentioning as well. They had less output power, but they also lacked the benefit of a huge turbocharger providing most of the boost pressure. The engines on F4F-4s (and especially F4F-5s) would apply.

The R-2800 was the only radial engine (possibly the only engine) in the US to see any serious development of big, high boost, high altitude, intercooled, water injected multi-stage supercharging and turbocharging. Then again, it was also the only radial engine being pushed into the cutting edge high performance fighters demanding that range of performance. Even the earlier model R-2800s were pushing volumetric performance beyond nearly any contemporary radial engine design, at least when water injection was used.

The BMW 801 F was coming close to that same range of performance, if not better in some respects, as were some Japanese designs. (particularly considering the material resource limitations compared to the Americans)

It took quite a while for water injection to be adopted as a routine part of operations. Many very late war Military aircraft and postwar commercial aircraft being given "wet" ratings for take-off vs using water injection for emergency combat use only. I don'y know if was just accumulated experience or different materials or different maintenance procedures or a combination. There were fears of corrosion and/or oil problems with early use of water injection. A lot may depend on when in the mission/flight the water injection is used. If used for take-off you have the length of the flight to evaporate any water out of the intake system and oil (blow-by past the piston rings) Using it 20 minutes before landing and using low power settings while descending to land could leave trace amounts of water in the oil.
In combat you do what you have to do. Planing to use it on every flight is another story.

Using it for take-off and emergency power only would be the context at hand. (also significant given the bulk and weight of WM/50 tanks, you wouldn't really want to employ it for significantly longer periods than take-off and emergency ratings are limited to)

Automatic boost control that locks maximum boost pressure when water injection is disabled (or has run dry) would be important to avoid easily damaging the engine with rapid detonation onset from overboosting.

 

[tomo pauk]

Since the thread is more or less engines-related:
Whenever the next type/variant of engines was introduced with C3 fuel in mind, German engine producers upped the compression ratio. That added a tiny bit of power at all altitudes, while lowering consumption, but made overboosting of the engine problematic, hence killing off plenty of advantages of using hi-oct fuel in the 1st place. For example, the Merlin III went to +12 psig boost on early 100 oct fuel (CR 6:1), the DB 601N went to 1.42 ata (circa +5.5 psig, CR 8.2:1) with early C3 fuel (96 oct?). The DB-601A was at 6.9:1, the 601E at 7.2:1.

Even once 1.80 ata was reached (late war C3 fuel, roughly equivalent of Allied 100/130?), that was still just under +11 psig. The compression ratio of the DB 605D was at 8.5/8.3:1 (from 7.5/7.3:1 on the 605A), 2-stage DB 603L have had the same CR.

Jumo engines were featuring a lower CR, 6.5:1 for B4 fuel (that includes 213 series), but also 8.5:1 when C3 fuel was aimed for. I'm not sure whether any engine was produced with such high CR, though.

An early incorporation of Polikovskiy's device (swirl throttle sub type, reverse engineered from captured Mikulin engines) on the DB 605 line might also be interesting, adding perhaps 100-120 PS under the rated height, even with B4 fuel? Can somewhat substitute the MW 50 or intercooler.
The Jumo 213 series have had it (ie. swirl throttle) incorporated.

 

[Koopernic]

"An early incorporation of Polikovskiy's device."

So what is this "swirl throttle" thing, how does it work and why would it work in a direct fuel injected engine. Perhaps the Soviet Engines were indirect multipoint injection?

AFAIKT a swirl device is an adjustable throttle applied to one intake port of a 2 intake port design to induce a certain amount of swirl at the cost of some losses. I would also question how applicable it would be to DB engines given the variable length inlet manifold.

Early C3 was 93-94 RON according to British Tests. The ratings of 96 or so came latter, certainly by 1943. There is a possibility that German C3 fuel improved again sometimes in 1944 or 1945 but we would have to find tests. It is a moot point however given the difficulties the Germans had in guaranteeing a secure supply of this complex to make product at that time. Most books I read of late war German aircraft mention a 2nd generation of Daimler Benz DB603 and Jumo 213 engines abandoned for a 3rd generation that could operate more successfully on B4 fuel. For instance the DB603EM (powered by C3 + MW50) might have powered the first Ta 152C however it required C3 fuel to reach its higher power levels and this was one reason that the Ta 152H with Jumo 213E1 was first to see production.

The Juners Jumo 213 aimed at RPM as high as 3700, much higher than the Merlin or Griffon.

 

[tomo pauk]

Swirl throttle was installed just before impeller in Mikulins and Jumo 213s, also on the DB 603L. Mikulins and Klimov engines have had carbs between impeller and cylinders, it was not much of trouble to install the swirl throttle on fuel injected engines.
More about the stuff:
http://www.ww2aircraft.net/forum/engines/superchargers-mikulins-klimovs-jumos-etc-40086.html