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The Fw 190 with in Line V12s, had the potentional to be more than equal for the allied fighters. However because of the war conditions several compromises were made that crippled the final result that went in production, as D-9. The compromises were
1) request to use B4 fuel, i remind that the Fw190A used C3 for almost all its career
2) quality of Construction (due to lack of skilled technicians, lack of Materials eg rubber to seal the engine gap, demand for gast production)
3) demand for very,very easy production. This resulted in design choises that added weight. eg the demand to deliver the engine as a complete power egg added weight, which in turned requested the extention of the rear fuselage which again increased weight
4)use of engines initially intended for bombers. Thus instead of a Motor cannon had druggy nose mgs with their heavy synchronization gear
5) lack of 2 stage superchargers, delayed beyond any hope again for production purposes
6)in order not to disturb production the same wing was retained. So the result was very High wing loading . By the time they decided that enough was enough and introduced new wings for the 190 family was far too late. For the same reson other improvements were not made eg fully retractable tail Wheel, lighter 20 mm guns etc
7) request for heavy armor and sophisticated radio equipment. Things nice to have but in combination with the weak engine the performance suffered
Because of the above reasons , i would agree with Tomo Pauk ,that the average D9 was generaly inferior to the 1945 anglosaxon fighters.
However when a D13 flew against a tempest post war proved decently competitive
I fully agree with this post.All good points. The timely introduction of 2-stage superchargers was maybe the greatest thing LW fighters lacked in 1944 (apart from plenty fuel and trained pilots).
Non-introduction of the DB 603A in the Fw-190 airframe might also be counted as a major mistake. A decent force of, we can call them 'Fw-190C's, was well within scope of the German war industry for the late 1943 (when the DB 603A is more or less debugged). The DB 603 (vs. the 'stock' BMW 801D) was offering less drag, greater power exhaust thrust at high altitudes, decreased consumption, better intake scoop (= better power at hi-alt), but I'm sure people know that already. Fuel was B4, another plus. Can use MW 50 system.
It also allowed for motor-cannon, so one can have a very useful bomber destroyer with MK 108 installed. The MK 108 as motor-cannon was indeed less draggy affair than twin MG 131s under cowling, when comparing drag data for the D-9 vs. D-12 or Ta-152H.
With that said, a major shortcoming of the D-9 was timing. Too late to matter, even jets were earlier in the combat.
The two stage superchargers are not magic. You need either good fuel, good inter-coolers or LOTS of MW50/water injection (or 2 out of 3) to get them to work.
P-38s were limited in power in the 20,000ft range even with 100/130 fuel due to poor intercoolers until the J model. Even the D and E were having problems trying to make 1150hp. The Turbo would deliver the pressure but the intake temperature was too high after the small inter-cooler. At 25,000ft you have to compress the air about 2.7 times just to reach sea level pressure. This raises the temperature of the intake air by hundreds of degrees.
Now you have to balance that against what the Germans wanted which was to get away from having to use C3 fuel. Initial planning being 1 to 2 years away from start of combat. A new refining process might have given them much more C3 fuel or some other factor might have changed things but it was NOT the smart way to bet.
With a power egg an annular/drum radiator is attached in front of an engine. According to a british test this kind of installation has less drag than other types, including leading edge radiators. Only the Mustangs cooling system is more effective in terms of thrust/drag.
Albeit the german ones had hinged gills and not sliding gills with the former getting a drag increase as the gills open.
The "Junkers radiator nose" should reduce this when replacing the normal radiator of the Doras that were not sufficient.
The British tests you speak of may be the ones carroed out by Napiers. Their annular radiator was quite different to the ones used by the Germans.
The German ones basically had the radiator wrapped around the prop shaft, but otherwise in the same orientation to the direction of flight of most radiators. Air flow was controlled by cowl flaps, like in radials.
The Napier system was different.
It also used a cowl ring to control air flow, similar to what the BMW 801 had in some versions.