You are correct in that the fan does not compress the air, and if you
read the statement I made I never said it was compressing the air. To
put it more precisely, without all those blades the airflow would not
be controlled enough to get high efficiency out of the compressor stages.
Robert
At 07:33 PM 4/3/2016, you wrote:
You aren't trying to compress much at all with the main fan, just move air.
There is a whole bunch of compressor stage equipment behind the fan, after the airflow is split, handling all that. Usually on entirely different spools on modern engines.
George William Herbert
Sent from my iPhone
> On Apr 3, 2016, at 1:46 PM, qbert@xxxxxxxxxxxxxxx wrote:
>
> At 01:37 PM 4/3/2016, you wrote:
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> Makes me wonder why smaller "traditional" ducted fans (like on airships or the E-fan aircraft) have much fewer blades, not a big blade disk like a turbofan.
>
>
> Ducted fans at the RC level are designed for thrust, after X number of blades you reach a minimum gain. In most of the high power ones it's around 12. In an actual turbo fan system you need to compress the air and for this, to few blades and you can't get the high compression needed to get to jet part of the system running at optimum efficiency.
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> Robert
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>
