multi-blade fans on aircraft - no Audi content

[Mike Arman <armanmik@n-jcenter.com>]

>>2.  The main reason for using multiblade fans is not to increase airflow=
> but
>>to eliminate noise.
>>
>>So any fan that was designed for a higher air flow will help in cooling
>>regardless of the number of blades so long as the engine RPM and the fan=
> RPM
>>are designed to work together.
>>
>>mark@anetinc.com
>>
>Those are fascinating observations.  I wonder how that relates to aircraft.
> I recall that the prototype Spitfire (help me out here, Phil) had a two
>bladed propeller, while the production version we're all familiar with used
>a 3 blade.  The P51 Mustang used a 4 bladed prop and I'm sure the designers
>weren't too concerned with noise.
>
>
>
>
>- -Tony
>

The purpose of the big fan on the front of an airplane is to keep the pilot
cool - if it stops, watch him sweat! (Sorry, guys - couldn't resist that
old chestnut.)

Multi-blade props can handle more horsepower - the first Spitfires had less
hp than the later models, and the Mustang (North American's version - NOT
Ford's VERY PALE imitation) had something like 1,500 HP, more available
short term with water injection, 1,650 HP, I think.

Look at a C-130 - you'll see four blade props with wide blades - has
something to do with "disc solidity", the C-130 engines are on the order of
3 or 4,000 HP each. DeHavilland is now using a five bladed prop on some
turbo props - it IS slightly quieter, but much more costly. Just like Audi,
vorsprung durch technic, and checkbooks be damned!

Best Regards,

Mike Arman