For what it's worth, some years back a German modeler, whose name I can't
now recall, and who apparently had the means to evaluate it, determined that
4 covers over exposed linkages (clevises, rods, horns, etc.) added 5-10% to
overall airframe drag.
This was of interest to me since I was then working out the details of an
all-internal system of moving flaps and ailerons which became the Rotary
Driver System, detailed in File 6 and File 3 of the Genie pages at
http://genie.rchomepage.com/.
While extensively experimenting with the RDS, I found out it did not matter
if the "pocket" that the "drive shaft" enters was high or low in the thin
surfaces we deal with. However, it was much easier to mount a pocket inside
the bottom surface so I usually stuck to that whether for flaps or ailerons.
I've now used some form of the RDS in over 60 airframes. They are
particularly quiet, suggesting that it is worthwhile to use an all internal
setup for moving surfaces.
An RDS installation is easy to do in home built, built-up or composite wings
or pre-built composite wings that can be purchased without wells cut in
them.
Pre-molded wells in moldies, however, are an obstacle to an RDS
installation, since it is preferable that the servos be angled relative to
the hingeline. 45 degrees is a very practical orientation and makes it easy
to get full down flaps.
----- Original Message -----
From: "D Hauch" <[EMAIL PROTECTED]>
To: <soaring@airage.com>
Sent: Tuesday, June 21, 2005 6:24 PM
Subject: [RCSE] top or bottom driven ?
hi all,
I've been asked this a few times, and I give my opinion,
but i want to see what you guys have to say.
What gets better mechanical advantage, top or bottom
driven linkage, and how much does the drag of bottom driven
really effect things, if any ?
My vote goes towards bottom driven.
I can always get the throws I want, easy to set up and adjust,
and gives a solid control surface.
Dave Hauch
www.git-r-built.com
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