Motor stick sideways bow?

From: Tapio Linkosalo <tapio.linkosalo_at_iki.fi>
Date: Mon, 05 Nov 2012 20:48:24 +0200

I have been recently working on my new F1M model. Initially it showed a
tendency to fly rather flat in the start, and this turned out to be too
loose rigging line, letting the stick bow, increasing downthrust and
reducing decalage. Tightening the line helped, now the model even tries
to stall in the start.

However, in the latest trim session I noticed that the tube now bows
sideways under full motor load. I have never seen such behaviour, and it
seemed so alarming that I decided to abandon flying that model before
strengthening the tube. I have not made up my mind yet: adding boron
would be the easiest way, but (to show the simplicity of the models to
our Finnish newcomers) I'm more tempted to replace the single rigging
wire with two, at an angle.

Anyway, my question is if this bowing is due to too stiff a rigging
wire, as the bow seemed to start only when I thightened it? I have been
trying to figure out the loads and geometry of the rigged stick; if the
support point in the middle is brought below the support points at the
ends, would this make the setup such that the setup is unstable
sideways? Thus, would only loosing the rigging slightly end the bowing?



-Tapio-
Received on Mon Nov 05 2012 - 10:48:29 CET