Quote:
Originally Posted by AndyJWest
The BMW-engined Fw 19Os had an engine-driven fan to increase airflow through the cowling. Presumably this must have taken some power to drive, and I could just about imagine the back pressure from a fully-closed cowl actually reducing available power - though whether this would be significant is hard to tell.
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The engine cowl isn't hermetic at all. Antons didn't need any cooling flaps openning till 1.32ATA included (and even higher, depending on air temperature and pressure), the 801 was actually an overcooled engine, as the time to put the engine to minimal take-off oil temp was the same as the time needed to a Merlin to blow up in the same situation, and Yes it did take some power, from memory 40PS, but the total engine power is calculated on the prop and not on the crankshaft as it is on English or American planes (see definition PS vs Bhp ), so when BWM says it's 1820PS, it is 1820PS on the prop, but when Rolls Royce says it's 1700Bhp you have to reduce that power with the power lost in the gear reductor.
Quote:
Originally Posted by JtD
The Fw 190 possessed an oil cooler ring, with an adjustable gap to adjust the cooling capacity. The standard size was 10 mm, but it had to be increased to 20 mm for tropical use and F model attack aircraft. This increase cost the plane 15-20 km/h at sea level. .
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Source please, nothing about it in the BMW801C/D maintenance and repair manual...or i missed it completely
Quote:
Originally Posted by JtD
The Fw 190 also had adjustable cooling gills on the side of the aircraft, which allowed the cooling of the engine or more precisely the cylinders. These pretty much worked like any other cooler on any other aircraft, including speed loss as it was opened. One effect I know of was a reduction of 500m in ceiling, therefore about 1 m/s in climb, with open cooling gills..
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The difference between a cooling grill with an max openning of about 5 cm, situated in the air flow + high pressurized exhaust gazes and letting out air itself with higher pressure than the surround air (prop fan beeing like a sort of compressor, extracting the heat from the oil radiator and pushing air into the admission intakes build inside the engine cover) and a frontal 1/2m² radiator, even with an adjustable airflow, seems to me like a drag difference between a truck and a race car.
So yes, the grills added certainly some parasite drag because it certainly broke the airflow on the fuselage in a certain matter but the effect should be not so important as 70kmh(from memory) between closed and open as it is in IL2. voilà
