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ject: push vs pull vis a vis rudders
From: "Derek Rowell"
Date: 03/27/2004 15:26 Pacific Standard Time
Message-id: E4o9c.108024$1p.1536914@attbi_s54

Would you all agree that in areas of dispute the truth may be revealed by an
experiment? Please try the following:
Take a fan, say a large house cooling fan (that's your propellor). Take a
flat surface, for example a stiff lightweight book (thats the rudder).
Turn the fan on and hold the rudder at an angle on the outflow side
(transmission in forward). Does the flow exert a torque (turning effect) on
the rudder? Let go one corner and see. Is there a sideways thrust that
you have to oppose to keep the rudder in position?
Repeat the experiment with the "rudder" on the inlet side of the fan
(transmission in reverse). Is there a turning effect (torque) or not? Is
there a sideways thrust on the "rudder"?
You tell me - I just did it. The answers to all four questions is yes.

Derek, you may be able to show a "force" being exerted on the rudder in this
way.
However, connect that rudder to a boat, and although this "force" may be
sufficient to pull that rudder further over (seen that), it will, EG almost
always, never be sufficient to act as a steering force for the boat to any
degree that is useable.
My apologies if I don't launch into some longwinded scientific dissertation.

Shen