Farmall M 7 blade fan

diesel cowboy · Dec 10, 2011

I have seen several 7 blade fans on M's lately. Wondering who made these? Are they as common as what I am seeing? I bet they sure would push much more air than an old 4 blade.

Bill Lisbon · Dec 11, 2011

The 7 blade fan was a factory option. They were used on tractors with mounted corn pickers and cotton pickers.

diesel cowboy · Dec 11, 2011

Really surprises me that it was an factory option. I figured it might have been an m+w deal.

Wardner · Dec 11, 2011

You are getting into fluid dynamic issues here. More blades don't necessarily move more air but they do increase the static pressure.

Consider wind mills, boat and aircraft propellers. KC-130 military cargo planes have more than three blades to increase their back pressure so they can use short landing strips. They are not more efficient than 3 bladed propellers or move more air. Almost certainly less air and less maximum air speed for the aircraft but I am not an aviation expert.

If an application needs to push or pull dirty air through a radiator, higher static pressure will help.

agpilot · Dec 11, 2011

Hi Wardner: Gotta be careful on aircraft props compared to close cowled fan on Farmall M. The close cowl changes the results quite a bit.
By the way, the very early P51 had 3 blades and then when more power was added they went with 4 blades of a wider design. Prop selection on aircraft is a very fussy issue. In talking props the outer part of the blades is the important area. On one ag plane decades ago I went with a longer blade but lower pitch. It helped a lot in getting a load off quicker when using gravel roads in Western wheat country.

sflem849 · Dec 12, 2011

(quoted from post at 20:25:02 12/11/11) Hi Wardner: Gotta be careful on aircraft props compared to close cowled fan on Farmall M. The close cowl changes the results quite a bit.
By the way, the very early P51 had 3 blades and then when more power was added they went with 4 blades of a wider design. Prop selection on aircraft is a very fussy issue. In talking props the outer part of the blades is the important area. On one ag plane decades ago I went with a longer blade but lower pitch. It helped a lot in getting a load off quicker when using gravel roads in Western wheat country.

The outer tip is very important on boat props as well. That is what gets a boat out of the hole and on plane.

Farmall M 7 blade fan

diesel cowboy

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Bill Lisbon

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diesel cowboy

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Wardner

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agpilot

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sflem849

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