I built my first attempt of F1D this autumn, but have not so far managed
to get it trimmed. The pmain dimensions are as per Big Square, but I also
too good look at Kagans model drawings when drawing my model. It came out
heavy though, 1.8 grams. My first attempt...
The thing is, I do not seem to get level flight out of the model. It
climbs some on the initial power burst (have flown with 1/3 motors, and
use back-off) then starts coming down pretty fast. Tried thicker rubber,
but it did not seem to make difference, also have reduced prop pitch
(which seems awfully low anyway, and this does not seem to have any effect
either. So I suspect there is something else going on. The decalage also
seems quite large (at least compared to F1M, but then D also has smaller
tailplane, so I guess more forward CG and more decalage is the way to go).
The model also seems to be very sensitive to decalage setting. At one end
it stalls, at with just a tiny bit of reduced decalage, it seems to dive.
And finally, when the stall accurs, it seems deep and model barely
recovers. I tried one flight with full motor, climbed six meters, then the
model stalled and made a "waterfall" all the way to the ground level, only
started flying again at 1 meter.
So the question is, what might cause all this? One thing that came to my
mind is that the fuselage/tailboom is too flexible. The weight of these
components is about 30 to 50% more than with "competitive" models, but the
balsa is not super (but rather Stiffness Coefficient a bit less than
100%), and I did not put boron to either tube or boom. The motor tube has
a rigging to take some load, though.
What kind of decalage should the model have, and what size of rubber is
used in F1D?
-Tapio-
Received on Sat Nov 04 2006 - 04:57:16 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET