What if the Luftwaffe technological gambles worked out?

tomo pauk said:

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

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I would call these a variable inlet guide vane, they would allow a degree of variability of the supercharger outlet pressure without the impairing of efficiency caused by throttling the air flow or the possible complexity of variable speed drive. Interesting that the Jumo 213 incorporated them.

They were known to Daimler Benz.
http://www.ww2aircraft.net/forum/en...628-a-28270.html?highlight=daimler+benz+DB628

The DB628 (a DB605 derivative) had a two stage supercharger.

The second stage was transversely mounted as usual in DB and Junkers A12 engines but the first stage was mounted coaxially to the gear box and had a variable inlet guide vane. It seems both the inlet guide vanes and impellor was variable pitch. The large size reflects that the engine was meant to operate at around 50000ft and would be taking in very thin air.

The 627 was a version based around the 603.

Indeed, the variable inlet guide vanes act as throttle, as noted from both Soviet and German reports.

tomo pauk said:

Indeed, the variable inlet guide vanes act as throttle, as noted from both Soviet and German reports.

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The suggestion there is that throttling of the air flow before the super charger is more efficient than throttling after the supercharger. In fact where did the German fuel injected engines throttle their air flow?
I was also under the impression that the carburettor on the Merlin was before the supercharger so as to obtain a charge cooling effect?

I also suggest that the variable incidence inlet guide vanes may have looked like throttling from a fuel preparation point of view it was a more efficient process that alleviated supercharger load.

The DB engines throttled the air after the S/C, until 2-stage engines emerged, those giving away that throttle and using 'swirl throttle' located at the 'entrance' of the S/C. The BMW 801 have had 2 throttle plates, located before S/C.

Back to the lowering compression ratio vs. increase of it:
With 5.5:1 compression ratio, the AM-42 engine was pulling manifold pressure of 1565 mm Hg (61.6 in Hg, a bit more than 2 ata, or about +15 psig) when using merely 95 oct fuel, no ADI, no inter/after-cooling. That was for take off and emergency at low level, making 2000 CV there.
The altitude performance of the AM-42 was nothing to write home about, though - the single-stage supercharger was with a single-speed gearing that was engineered for low alt performance.

Koopernic said:

The suggestion there is that throttling of the air flow before the super charger is more efficient than throttling after the supercharger. In fact where did the German fuel injected engines throttle their air flow?

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The manual for the AM-42 notes that pressure just behind the supercharger was 1720 mm Hg, while just behind carbs was down to 1565 mm Hg (= manifold pressure, 'useful' for cylinders) when engine was in take off or emergency regime at low altitude. So the carb lowered the pressure by 155 mm Hg, or 6.1 in Hg - quite a bit of the loss, worth maybe 150 CV down low? Of course, the impeller needed/consumed more power to drive to supply 1720 mm Hg than for 1565 mm Hg.
To the best of my knowledge, the Jumo 213 was using only the swirl throttle for all the throttling (no carb what so ever, of course), so the throttle-related it's losses should be lower than at Mikulins?

With DB engines, we can see that supercharger was delivering, say, 1.7 ata at sea level, yet it was throttled down to 1.3 ata (here). 'Geblasedruck' is the pressure delivered by supercharger, 'Ladedruck' is manifold pressure ie. pressure after the supercharged air is throttled down. Of course, any surplus amount of 'Geblasedruck' vs. 'Ladedruck' means that a bit of engine power is wasted. The discrepancy between Geblasedruck' and 'Ladedruck' is much lower above full throttle height.

I was also under the impression that the carburettor on the Merlin was before the supercharger so as to obtain a charge cooling effect?

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Maybe it was a happy coincidence? An engine with single big carb (RR engines, V-1710) should be an easier thing to design, produce and maintain than an engine featuring multiple smaller carbs (Hispano V-12s, Kllimov and Mikulin V-12s). Single carb in front of the S/C might also need protection from icing, along with installation of backfire screens if greater manifold pressures are aimed for. Those two items might eat up any advantage provided by fuel acting as charge cooler.

Koopernic said:

I would call these a variable inlet guide vane, they would allow a degree of variability of the supercharger outlet pressure without the impairing of efficiency caused by throttling the air flow or the possible complexity of variable speed drive. Interesting that the Jumo 213 incorporated them.

They were known to Daimler Benz.
http://www.ww2aircraft.net/forum/en...628-a-28270.html?highlight=daimler+benz+DB628

The DB628 (a DB605 derivative) had a two stage supercharger.

The second stage was transversely mounted as usual in DB and Junkers A12 engines but the first stage was mounted coaxially to the gear box and had a variable inlet guide vane. It seems both the inlet guide vanes and impellor was variable pitch. The large size reflects that the engine was meant to operate at around 50000ft and would be taking in very thin air.

The 627 was a version based around the 603.

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Do you have the rest of the patent on that link?

tomo pauk said:

The manual for the AM-42 notes that pressure just behind the supercharger was 1720 mm Hg, while just behind carbs was down to 1565 mm Hg (= manifold pressure, 'useful' for cylinders) when engine was in take off or emergency regime at low altitude. So the carb lowered the pressure by 155 mm Hg, or 6.1 in Hg - quite a bit of the loss, worth maybe 150 CV down low? Of course, the impeller needed/consumed more power to drive to supply 1720 mm Hg than for 1565 mm Hg.
To the best of my knowledge, the Jumo 213 was using only the swirl throttle for all the throttling (no carb what so ever, of course), so the throttle-related it's losses should be lower than at Mikulins?

With DB engines, we can see that supercharger was delivering, say, 1.7 ata at sea level, yet it was throttled down to 1.3 ata (here). 'Geblasedruck' is the pressure delivered by supercharger, 'Ladedruck' is manifold pressure ie. pressure after the supercharged air is throttled down. Of course, any surplus amount of 'Geblasedruck' vs. 'Ladedruck' means that a bit of engine power is wasted. The discrepancy between Geblasedruck' and 'Ladedruck' is much lower above full throttle height.



Maybe it was a happy coincidence? An engine with single big carb (RR engines, V-1710) should be an easier thing to design, produce and maintain than an engine featuring multiple smaller carbs (Hispano V-12s, Kllimov and Mikulin V-12s). Single carb in front of the S/C might also need protection from icing, along with installation of backfire screens if greater manifold pressures are aimed for. Those two items might eat up any advantage provided by fuel acting as charge cooler.

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Clearly the DB605A hydraulic variable speed drive lacked sufficient range of operation at sea level to reduce the supercharger output to the 1.3 ata manifold limit. Running the supercharger faster than necessary and thereby generating 1.7 bar of pressure only to have to throttle it back to 1.3 bar manifold limit is clearly a source of inefficiency.

The DB603N was to have the two mechanical gears plus the hydraulic variable speed drive and presumably also variable pitch inlet guide vanes. The gears sets could easily be changed to adjust ratios for different missions.

Some method to is required to measure or estimate the air mass flow in an engine so that the fuel supply can be proportioned in at the approximate stoichiometric ratio of 14:1 for air fuel mixtures. the classic method is a venturi or orifice plate to generate a pressure differences which can be measured or which can be used to draw in fuel from a float chamber by a capillary tube.

Such a venturi obviously will lead to an pressure loss that is undesirable at times that the engine is to generate maximum power or at least it represents work the supercharger is performing to no purpose.

An alternative method is to measure ambient or exhaust pressure temperature and use a 'map' (say via a cam if you don't have a computer) of say inlet static pressure versus engine RPM to estimate the fuel flow and then apply the resultant mechanical deflection to a variable displacement pump (cam on the BMW 801 to operate individual plunger pumps or swash plate pumps on late Merlins)

The ideal system of flow control of the air would be if the throttling would be one in which there were no suction losses:
1 Adjustable supercharger via infinitely variable drive and or variable inlet geometry to allow adjustment from 1 bar ambient pressure with no losses in the supercharger drive all the way to maximum allowed manifold pressure with no losses in throttling back the pressure.

2 For manifold pressures below ambient fairly radical idea would be to not have a throttle valve but instead have a variable pitched fan that could change from being a compressor to being a turbine that adds power back into the main shaft. Thus the energy lost in restricting airflow then some of the the 'suction losses' of a internal combustion engine are recovered.

I suspect that, to a limited degree, that these variable pitch inlet devices can be conceived of as working somewhat this way: they restrict the inlet flow but also make that flow impinge on the compressor inlet in such a way that it actually perhaps a certain degree part of the compressor becomes a turbine that adds back power to alleviate the power drawn by the main compressor portion.

My understanding is that the 1st stage of USN two stage PW R-2800 navy fighter engines could be declutched to 'free wheel'. Imagine if throttling were achieved via extracting power from this 1st stage via a dynamo/generator. I suspect that this is in fact what the electric superchargers on some Ford cars do.

stona said:

There were NO dual Spitfires or Hurricanes available to the RAF during the war. Pilots were given a copy of the Pilot's Notes to read, a few hints and tips from someone who knew the ropes and told to get on with it. The same applied for those converting from Hurricane to Spitfire or vice-versa (which did happen, sometimes to the dismay of the pilots concerned).
If, and its a big if, the Bf 109 had an unusually high accident rate for newly qualified pilots, then there are factors other than the aircraft's handling that might need consideration. The Luftwaffe seems to have had a poor safety record generally and this was as much due to its procedures, or lack of them, as the aircraft it flew.
Cheers
Steve

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Yes but one reason might be that the jump from Ar 96 (485hp, MTOW 1750kg) to Bf 109 was bigger than from Miles Master Mk II(870hp, 2528kg)/NA Haward (550hp, 2404kg) to Hurricane (very easy a/c to fly for a first-line fighter) or to Spitfire (markedly easier plane to t/o and land than 109 even if as a pure flying machine 109 was fairly pilot friendly).

Koopernic said:

Clearly the DB605A hydraulic variable speed drive lacked sufficient range of operation at sea level to reduce the supercharger output to the 1.3 ata manifold limit. Running the supercharger faster than necessary and thereby generating 1.7 bar of pressure only to have to throttle it back to 1.3 bar manifold limit is clearly a source of inefficiency.
.......
.

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I think the real reason for the pressure differential was to provide a rapid throttle response - if you tried to replace the throttle with a variable speed supercharger drive, the result would be a poor throttle response because of the time required to increase the supercharger speed. The swirl throttle avoided this problem.

Juha said:

Yes but one reason might be that the jump from Ar 96 (485hp, MTOW 1750kg) to Bf 109 was bigger than from Miles Master Mk II(870hp, 2528kg)/NA Haward (550hp, 2404kg) to Hurricane (very easy a/c to fly for a first-line fighter) or to Spitfire (markedly easier plane to t/o and land than 109 even if as a pure flying machine 109 was fairly pilot friendly).

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Compared to the Fw 190 the Me 109 required extra instruction time to deal with the more difficult take-off and landing. The poor rearward vision also required extra instruction to ensure the paired wing men had developed good habits to cover each others tail. The more difficult takeoff and landing was considerably improved when the extended tail yoke was introduced. Take-off and landing accidents reduced as did taxiing incidents. I'm surprised that this took so long to introduce as the extended tail yoke was interchangeable with the shorter form. The enlarged tail also likely improved things.

A statistic I recall from the wild boar era of single engine night fighter training in Germany is that these pilots were suffering a 40%-50% casualty rate in training compared to their already experienced and skilled Finnish counterparts, receiving training in Germany at the same time, at less than 10%.

The rearward visibility was improved with the clear view ERLA haube(canopy hood) which removed much of the cockpit framing and the Galland Panzer which was the replacement of the pilots head armour with a plate of armour glass across virtually the entire canopy width.

Nevertheless without a bubble canopy or rear view mirror they must have been restricted to using flying procedures to avoid being jumped unawares. This seemingly simple aspect is actually quite significant.

German flight instructors were somewhat disappointed that the Luftwaffe had found itself dependant on the Me 109 even in 1944. Obviously the Luftwaffe had done a good job in introducing the Fw 190 and the aircraft showed excellent development potential but it had limitations at high altitude. History might have changed had the DB603 not been put on 'hold' between 1937 to 1940. It had been offered to the RLM/Luftwaffe as a 1500hp-1600hp engine in 1937. Development did continue at a slow rate, presumably as a Daimler Benz project. Obviously the options available to German designers and manufacturers change dramatically if the engine is available in 1940.

The Me 309, which flew in early 1942 had a laminar flow wing, 80% more range than the Me 109, Me 262 style bubble canopy, tremendous fire power, tricycle under carriage, reverse pitch propeller. It might have addressed the take-off/landing issues of the 109. Supposedly it was less manoeuvrable than the Me 109 but reading between the lines I think this was entirely a power to weight ratio issue. The first prototype had the DB603 but the subsequent ones seemed to receive the relatively tiny DB605, suggesting that a production problem with the DB603 was the cause. Of course ramping up from first flight in early 1942 to production might take 2 years if the handling suggested that airframe design needed adjustments and 1 year if it was good from the begining. It might have entered service at the time of the British Tempest in 1944. Either way the size of the aircraft demanded an engine of around 2000hp. Throwing away the 109's widely dispersed productions and sub supplier system would have seemed unattractive.

Koopernic said:

Compared to the Fw 190 the Me 109 required extra instruction time to deal with the more difficult take-off and landing. The poor rearward vision also required extra instruction to ensure the paired wing men had developed good habits to cover each others tail.

Nevertheless without a bubble canopy or rear view mirror they must have been restricted to using flying procedures to avoid being jumped unawares. This seemingly simple aspect is actually quite significant.

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I wonder if the He 100 would have fared better in those categories given the wider track landing gear configuration and higher visibility canopy design.

The high wing loading might have complicated matters though, assuming the wing design of the D-0/D-1 series went unchanged. (at least assuming significant weight increases on hypothetical later models)

German flight instructors were somewhat disappointed that the Luftwaffe had found itself dependant on the Me 109 even in 1944. Obviously the Luftwaffe had done a good job in introducing the Fw 190 and the aircraft showed excellent development potential but it had limitations at high altitude. History might have changed had the DB603 not been put on 'hold' between 1937 to 1940. It had been offered to the RLM/Luftwaffe as a 1500hp-1600hp engine in 1937. Development did continue at a slow rate, presumably as a Daimler Benz project. Obviously the options available to German designers and manufacturers change dramatically if the engine is available in 1940.

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Again, the He 100 might have filled the role of an aircraft more deserving of the DB-601/605. (as might the Fw 187, purely hypothetical designs aside)

But as for the Me 309, I think the Fw-190 airframe itself would be a more deserving target for that engine. (more than the bombers and heavy fighters it was actually going to as well) Accelerated development earlier on would have been great, but as it was it would have made much more sense to focus on supplying the limited number of DB-603As to Fw-190 derivatives.

A DB-601/605 with the larger 603's supercharger could/should have been developed sooner as well. (in the case of the 605, an earlier DB 605AS coupled with a lightened, high-alt optimized airframe might have been attractive as well -as would be the potential motor cannon mounting -an earlier 605ASM would be even better, but I'm not exactly sure what held up water injection development)

Both the Me 309 and the He 100 show some of the problems with trying to get too tricky.

Me 309 maneuverability may not have been helped by being under powered but the fact that it was as heavy or heavier than a P-51 Mustang with a wing only 77% as big certainly didn't help either.

Trying to shove a quart (liter) into a pint (500ml) pot doesn't work too well. And that is the story of the He 100. Some of it's features were better than the 109 but the plane had been designed a little too carefully to be as small as possible for the engine it used. It's wings were about 90% the size of the 109s wings and held most of the fuel (or all depending on version) which meant large area flat tanks. These were not self sealing on the prototypes/early series aircraft. A large weight increase/range reduction on a version with protected tanks. A similar problem with the oil cooling system. Oil cooler was suspended in an alcohol tank with the alcohol running to surface radiators in the turtle deck, horizontal stabilizers and vertical fin. A lot of square footage of vulnerable area. It also means engine upgrades are going to harder to do or increases in performance are going to be harder to achieve. Increasing engine power(not peak but climbing power) by 30% means you need 30% more cooling capacity for both the radiators and oil cooling system. If you run out of skin area you need to use higher drag regular cooling systems.
A service version even in 1941 comparable to a Bf 109F would have seen a sizable jump in weight.

Shortround6 said:

Trying to shove a quart (liter) into a pint (500ml) pot doesn't work too well. And that is the story of the He 100. Some of it's features were better than the 109 but the plane had been designed a little too carefully to be as small as possible for the engine it used. It's wings were about 90% the size of the 109s wings and held most of the fuel (or all depending on version) which meant large area flat tanks. These were not self sealing on the prototypes/early series aircraft. A large weight increase/range reduction on a version with protected tanks. A similar problem with the oil cooling system. Oil cooler was suspended in an alcohol tank with the alcohol running to surface radiators in the turtle deck, horizontal stabilizers and vertical fin. A lot of square footage of vulnerable area. It also means engine upgrades are going to harder to do or increases in performance are going to be harder to achieve. Increasing engine power(not peak but climbing power) by 30% means you need 30% more cooling capacity for both the radiators and oil cooling system. If you run out of skin area you need to use higher drag regular cooling systems.
A service version even in 1941 comparable to a Bf 109F would have seen a sizable jump in weight.

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It seems like a lot of the problems were being resolved on the He 100 D-1 variant, at least as far as abandoning the surface cooling entirely. I'm not sure if that would have freed up any more wing space for fuel (or enough to make up for the reduction in capacity for self-sealing tanks -weight gains aside).

The under-fuselage radiator position would have precluded a belly rack, so limiting things more in line with the Hurricane or P-51 (or Ki-61 or some Italian fighters) with underwing racks or nothing at all.

Wing extensions/redesigns might have been needed at some point (the Ki-61 adopted such over the Ki-60), though I wonder if underwing/wing-tip drop tanks (or even fixed fuel tanks) might have changed things somewhat too. The wings are small enough to make that somewhat attractive over underwing tanks, but aside from that you have the advantages of winglet-like improvements to lift:drag and effective aspect ratio. (not fully understood at the time, but the 'endplate effect' was at least known and one of the reasons for using twin-fin tail designs, so at least more reason to consider that than a potential happy accident in hindsight)


All that said, a Fw-190 variant optimized for the DB-605 might have made more sense than either the He 100 or Me 309. (should at very least have been lighter than the 309 with the same engine and had more flexible armament configurations, cockpit visibility, handling, and landing characteristics than the 109, but still probably a lower power:weight ratio than the 109, even with possible weight reductions -then again, the P-51 generally had lower power:weight as well)

A DB 601E powered 190 probably wouldn't have gained enough to be worthwhile ... maybe close to (or better than) the P-51A, but the trade-offs compared to the 109 might have been too much to be worthwhile. (at least in fighter vs fighter performance ... not sure how the other advantages might factor in)

The DB-601AS AM and especially ASM would be the most interesting to consider, but the latter in particular was late. (had water injection or -especially- a larger supercharger been introduced earlier, use on the larger Fw 190 airframe would be more interesting -possibly to the extent of making the DB-601E more attractive ... a DB-601ES or ESM, if you will)

That and, if provided with the same C-3 fuel some of the 801 powered Fw-190s were receiving, the boost limits on the DB-605A might have been more forthcoming too. (possibly the 601 as well)

Resources, resources, resources.

The Luftwaffe NEVER had anything like the resources it needed to fulfil existing production plans. This is something that started before the war. Production Plan 11 was introduced in early 1939 and reduced the total aircraft production to what was then considered more realistic levels than the earlier plans. It called for 7,748 bombers rather than the 10,900 of the previous plan for example.

Even Production Plan 11 proved unrealistic.

On 12th April the RLM reported that due to changes in aircraft and equipment types and other shortages Plan 11 could not be completed on time. In May Milch informed Goering that aircraft production plans were in trouble due to a lack of steel, aluminium, copper and other metals. He proposed a reduction of 35% in the plan.
To cut a long story short (there were also shortages of fuel, ammunition, bombs etc) Plan 12 was introduced cutting targets by 20%. Engine production was running at between 3% and 37% below target, depending on manufacturer.

This is all before a shot has been fired in WW2.

In August 1939, after the start of hostilities the Luftwaffe requested priority for the Bf 109, He 177, Ju 88 and Me 210. This was agreed at a meeting of Goering, Jeschonnek, Milch and Udet.
My point is that as early as 1939 a lack of resources was causing concentration on a few types. Technological gambles are all well and good if they can be properly financed and resourced. The Germans couldn't do it in 1939/40 and they were even less able to do it later when resources were diverted to the V weapons, a technological gamble that didn't pay off, and other projects, some of which, with hindsight, verge on idiotic.

There is a common misconception that the Germans somehow had an over arching technological lead over the Allies. They certainly didn't and in many fields they had fallen somewhat behind by the end of the war. Radar would be a good example of this. The Germans pushed some technologies (rocketry for example) further than the Allies because they felt had to. There were obviously ideological rather than pragmatic reasons for this. It did result in rare technological successes, but never anything that came close to altering the course of the war.

Cheers

Steve

stona said:

There is a common misconception that the Germans somehow had an over arching technological lead over the Allies. They certainly didn't and in many fields they had fallen somewhat behind by the end of the war. Radar would be a good example of this. The Germans pushed some technologies (rocketry for example) further than the Allies because they felt had to. There were obviously ideological rather than pragmatic reasons for this. It did result in rare technological successes, but never anything that came close to altering the course of the war.

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Mismanagement of what resources they did have (material and intellectual) was a big part of that problem, but then so were unrealistic (or even insane) plans or goals be it strategic or tactical, military or fundamental economic planning. (sticking with the purely technical side of things and not getting into the bigger social/political picture)

Nazi economic planning and management (or lack thereof) was one of their fundamental flaws. Honestly, the majority of the technical discussions on here with any emphasis on better emphasis on X engineering project or X distribution of resources only start to get hypothetically plausible if you start skewing the history of Nazi doctrine/policies in general.

stona said:

Resources, resources, resources.

The Luftwaffe NEVER had anything like the resources it needed to fulfil existing production plans. This is something that started before the war. Production Plan 11 was introduced in early 1939 and reduced the total aircraft production to what was then considered more realistic levels than the earlier plans. It called for 7,748 bombers rather than the 10,900 of the previous plan for example.

Even Production Plan 11 proved unrealistic.

On 12th April the RLM reported that due to changes in aircraft and equipment types and other shortages Plan 11 could not be completed on time. In May Milch informed Goering that aircraft production plans were in trouble due to a lack of steel, aluminium, copper and other metals. He proposed a reduction of 35% in the plan.
To cut a long story short (there were also shortages of fuel, ammunition, bombs etc) Plan 12 was introduced cutting targets by 20%. Engine production was running at between 3% and 37% below target, depending on manufacturer.

This is all before a shot has been fired in WW2.

In August 1939, after the start of hostilities the Luftwaffe requested priority for the Bf 109, He 177, Ju 88 and Me 210. This was agreed at a meeting of Goering, Jeschonnek, Milch and Udet.
My point is that as early as 1939 a lack of resources was causing concentration on a few types. Technological gambles are all well and good if they can be properly financed and resourced. The Germans couldn't do it in 1939/40 and they were even less able to do it later when resources were diverted to the V weapons, a technological gamble that didn't pay off, and other projects, some of which, with hindsight, verge on idiotic.

There is a common misconception that the Germans somehow had an over arching technological lead over the Allies. They certainly didn't and in many fields they had fallen somewhat behind by the end of the war. Radar would be a good example of this. The Germans pushed some technologies (rocketry for example) further than the Allies because they felt had to. There were obviously ideological rather than pragmatic reasons for this. It did result in rare technological successes, but never anything that came close to altering the course of the war.

Cheers

Steve

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Yet the Germans were highly dependent on horses.
How many UK and US horses were deployed during the war?

gjs238 said:

Yet the Germans were highly dependent on horses.

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Again a reflection of resources (or lack thereof). The Germans obviously had the technology to build motorised transport, just not the means to build the quantity that could be turned out of US factories in particular.

Prior to D-Day 140,000 transport vehicles were parked at depots around the south coast of England. There were 100,000s more to follow. What the Germans would have given for them.

Worthwhile technological advances need not necessarily be huge leaps. 34% of British armoured losses after the Rhine was crossed i.e. east of that river, were due to the cheap and cheerful 'Panzerfaust'. That compares with just 6% in Normandy and 9% in Belgium and Holland. It was a weapon much superior to the US 'bazooka' or laughable British PIAT, was manufactured in large numbers and handed out to just about anyone that could hold one.

Cheers

Steve

Shortround6 said:

Both the Me 309 and the He 100 show some of the problems with trying to get too tricky.

Me 309 maneuverability may not have been helped by being under powered but the fact that it was as heavy or heavier than a P-51 Mustang with a wing only 77% as big certainly didn't help either.

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The Me 309 had full span leading edge slats, those on the 109(like many aircraft) covered only the aileron area. That in itself would increase CLmax by 40% such that the 77% wing area compared to the P-51 becomes 108% lift loading. Although slats increase CLmax considerably they do so by allowing far higher angles of attack before airflow becomes detached. Although these higher permisable angles of attack provide the desired extra lift they do so at a lower Lift to Drag ratio. These is more drag. Hence power to weight ratio is important in such aircraft: they are efficient at level flight but under conditions of high load will have more drag.

The Me 309 flew in Early-Mid 1942 around the time the Me 210/410 issue had damaged Messerschmitt's reputation and had sent the company insolvent. The extra workload in the Drawing and Engineering office was such that Messerschmitt had to forgo development of the Me 264 transcontinental bomber.

These issues and perhaps Milch's animosity may have played their part. The powers that be also wanted Messerschmitt to focus on the Me 262.

It is difficult to find terribly much information on this aircraft. It was flying May-June 1942. If one assumes a 3 month flight test program, then a few months of modifications say a lengthened tail(say a 75cm plug), enlarged empennage and perhaps slightly enlarged wings one ends up with an aerodynamically debugged aircraft by mid 1943. A few moths after that A0 series pre production aircraft can begin squadron testing, perhaps undertaking combat, developing tactics and training manuals. Production thus feasibly begins in early 1944. A key problems will be the engines: either DB603 or Jumo 213. Neither seems to have exceeded 1750hp in production form until well into the second half of 1944. The Fw 190D9 itself had lacklustre performance until the increased boost modification increased power from 1750 to 1900hp in October and the MW50 addition to 2100 around November.

The Me 309 certainly seems to have had good performance on the 1750hp engine. It reputedly did 452 mph on 1725hp and supposedly around 462 on 1900. Moreover it had many features of what the Luftwaffe needed, a bubble canopy with spectacularly good rear vision, enormous fire power, improved range.

It seems more likely it was the victim of circumstance and timing. A completely new aircraft entering mass production in 1944 would have been a challenge for any nation.

It seems more likely that it was abandoned due to the circumstances around it.

stona said:

Again a reflection of resources (or lack thereof). The Germans obviously had the technology to build motorised transport, just not the means to build the quantity that could be turned out of US factories in particular.

Prior to D-Day 140,000 transport vehicles were parked at depots around the south coast of England. There were 100,000s more to follow. What the Germans would have given for them.

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I'm not sure it's pure material resources that limited a transportation evolution/revolution in Germany, but at very least the overwhelming issues with industrial management (and overall economic planning/management) would come into play here.

German logistical management and transportation network were a bit of a mess in many areas, that extended to the bulk of the military transport aircraft used during the war (the shortcomings of the outdated Ju 52 and lack of a suitable replacement in production came up recently in other discussions).

Worthwhile technological advances need not necessarily be huge leaps. 34% of British armoured losses after the Rhine was crossed i.e. east of that river, were due to the cheap and cheerful 'Panzerfaust'. That compares with just 6% in Normandy and 9% in Belgium and Holland. It was a weapon much superior to the US 'bazooka' or laughable British PIAT, was manufactured in large numbers and handed out to just about anyone that could hold one.

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There's a lot to be said about elegance in simplicity and efficiency. The Volkswagon design philosophy fit in pretty well there too. (on the topic of transportation)

There are some cases where the Germans favored overly conservative development/production that hindered flexibility and adaptation (the distribution of DB-601/605 and 603 engines would be one example -limiting possible replacements for the 109/110/210/410 -and others- that would render allocation of engines to those aircraft superfluous anyway), in other cases they funded far too broad an array of newer/bigger/more complex/costly designs rather than paring them down to the most efficient/effective designs. That was particularly true for offensive weapon investment over defensive. (bombers, attack aircraft, armored fighting vehicles, the V weapons)

Low priority for transport aircraft development/production was one of the more serious logistically crippling faults as well.

Then you had the overall economic strategy for the war barring things like stockpiling material resources in case of shortages, or any sort of contingency planning in the case of prolonged conflict.

Koopernic said:

The Me 309 had full span leading edge slats, those on the 109(like many aircraft) covered only the aileron area. That in itself would increase CLmax by 40% such that the 77% wing area compared to the P-51 becomes 108% lift loading. Although slats increase CLmax considerably they do so by allowing far higher angles of attack before airflow becomes detached. Although these higher permisable angles of attack provide the desired extra lift they do so at a lower Lift to Drag ratio. These is more drag. Hence power to weight ratio is important in such aircraft: they are efficient at level flight but under conditions of high load will have more drag.

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Aside from greater drag and energy loss in maneuvers (high G mid/low speed ones that actually approach CL-max at least) you'd also have difficulty with visibility on landing due to the nose high angle at low speeds. On the positive end, you'd also have the ability to pull more lead on a target without stalling out. (important for instantaneous maneuvers, so potentially outside the unattractive realm of sustained, high energy cost turning)

The Me 309 flew in Early-Mid 1942 around the time the Me 210/410 issue had damaged Messerschmitt's reputation and had sent the company insolvent. The extra workload in the Drawing and Engineering office was such that Messerschmitt had to forgo development of the Me 264 transcontinental bomber.

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Again, given the timing, it still seems like investing in alternate engined variants of the Fw 190 around the same time (or sooner) would have been smarter. For that matter, adapting the original smaller Fw 190 V1 airframe to test with a DB 601/605 might have been very useful as well.

Until mid 1941 all armaments contracts were annual contracts on a 'cost plus financing' basis. It means that the company is immune from losses if for example a weapon takes extra time to develop and get into production. There is also no incentive to produce more, faster or more efficiently. This is just one example of the malaise that lay at the heart of the Nazi government's cosy relationship with industry in general.

It has been estimated that the German motor industry was still operating at less than 50% capacity for military vehicles in 1942. The huge Steyr Werkes in Austria was still unoccupied in 1943!

Hoarding of raw materials was an endemic problem within industry and the aircraft industry was one of the worse offenders. This was partly due to the quota system exercised by the RLM. Companies consistently over estimated their needs assuming they would get less than whatever they asked for and then stockpiled any excess against future shortage.
There is some evidence that raw materials intended for the armament and related industries were diverted into consumer goods production. In 1942 the production of consumer goods in Germany was running at a rate only 3% lower than before the war. Corruption was rife in the Nazi system.

There was also considerable wastage due to inefficient techniques (one report estimates that a staggering 700Kg of aluminium was 'wasted' in the production of one aero engine) and inappropriate uses. Messerschmitt was still using aluminium to manufacture pre-fabricated barracks for the Navy and ladders for vineyards in 1943.

Other 'technological gambles', even those which did enjoy some success were fraught with problems. In November 1943 2,000 partially completed V-1s were scrapped due to 'structural weaknesses'.

Cheers

Steve