Subject: Re: [harryproa] re: rudder traveller
From: "Rob Denney" <proa@iinet.net.au>
Date: 4/24/2007, 9:43 PM
To:
Reply-to:
harryproa@yahoogroups.com.au

G'day,
 
The rudders have to be away from the hull so they can turn.  Full rotation is desirable.  One thing I have discovered is never to use the word 'just' when thinking about proa rudders!  I did try the Speer assymetric foils.  Good for daggerboards, less so for rudders.  The balance requirement makes them very difficult to arrange.
 
Kun Fett is an extraordinary looking craft!  In some of those pictures it seems to be going extremely well.   What happens when the angle of the tow load varies?
 
regards,
 
Rob
----- Original Message -----
From: sigurd grung
To: harryproa@groups.yahoo.com
Sent: Tuesday, April 24, 2007 12:13 PM
Subject: [harryproa] re: rudder traveller

If you have a flat deck anyway, the top rail tube
would be bonded all the way directly to the deck edge,
which protruded a bit. the plastic bearings would be
splitted. still not so nice to be using a lot of extra
material.

breakaway attachment to bottom bearing? I'm still
seeing full power after a shunt with the rudder jammed
tail forward clenched to the hull, somewhere along the
rail. I'm assuming you are going to use limited
rotation rudder?

Or the rudder is on a swinging arm, mounted in the
middle of your lw hull, where the mast is anyway. just
steer it into its little lock on the rear of the new
tack, incidentally just where the aka is.

Are you ever using zero or negative lift with only one
rudder no board?
I know you used and discarded some tom speer section
rudders once, but IIRC you said they were 30212, which
are so cambered that they don't look like they will
work close to zero lift. 30112 has its drag bucket
moved so that CL -0.1 is probably just inside? very
abrupt bucket so probably just above best LD it goes
straight into the toilet. If there were structural or
safety gains then it might be worth a try but as you
know they must be raked back or something. Maybe not
so hard to do if you already have functional rails.

check out my towed proa model kun fett here:
http://www.flickr.com/photos/66507020@N00/sets/72157594398800945/


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