Although I am not sure I will go for a 3.6 CG but the point with rotation on
launch is something to look at.
Some of the F3B guys use a couple of flight fases for this. They start of
with one and deppending on the conditions go for two alternatives deppending
on the pull they feel the are getting.
The overshoot on the rotation can be minimized a whole lot by throwing well.
But the problem can be that with braided line and strong motors (when there
has not been a build up of the drum size) one can not tension up that much.
Good thread ;-)
Hilsen (Regards) Jojo
NEW: www.jojoen.no
Date: Wed, 04 Jan 2006 16:44:07 -0500
From: Mark Drela <[EMAIL PROTECTED]>
To: soaring@airage.com
Subject: RE: [RCSE] Supras done
Message-ID: <[EMAIL PROTECTED]>
-----snipp----
This is rather far aft hook position which requires
special action during launch. On my Evo program the
left slider is an elevator (speed) trim with a small gain.
For the launch throw I push the slider all the way forward
which feeds in a slight amount of down-elevator.
Once the glider rotates and settles down in the climb,
I pull the slider back to its normal center position
for maximum load just short of stall. I have 100% Ail.Diff
and lots of Ail->Rud coupling during launch, so I can
steer with might right thumb, leaving the left thumb
free to work the slider.
PS
I've done some sims of the initial pitch dynamics
immediately after the throw. There is a very significant
CL overshoot at the end of the initial nose-up rotation.
So if you trim the glider for maximum pull during the
climb and zoom, and throw with this trim, then you are
guaranteed to stall at the top of the nose-up rotation.
So for maximum launch performance, it is necessary to add
some initial nose-down trim to safely get past the
initial pitch transients after the throw.
------------------------------
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe
messages must be sent in text only format with MIME turned off. Email sent from web based email
such as Hotmail and AOL are generally NOT in text format
