Radi C ntr lled - Radio Controlled Soaring Digest

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wind slope machine. I fully expected
them to go straight in the bin after the
first flight.
How wrong could I have been! I
maidened the model with “that looks
about right” control throws. From the
outset it instilled confidence, feeling
solid in flight, happily scratching around
in the 4 mph draft. Since the maiden it
has proven to be a versatile machine,
comfortably flying in a 20mph breeze.
This success pushed me on. Because of
the rough finish, it seemed logical to use
the model as a test bed so I decided to
try out some flaps. I’d made an attempt
at them on a 100" wing, but lack of
knowledge about sizing and placement
meant when deployed, they gave an
uncontrollable pitch up. The flaps
extended too far inboard, so a downward
deflection (ahead of the pitch axis)
had the effect of up elevator. As down
elevon at the tips produces a nose down
reaction, I concluded that there must be
a flap size where there is no pitch effect
when deployed.
I needed the input of greater minds
than mine to resolve this one, so I
posted on RC Groups with a request
for design help. Norman Masters came
The 100" wing pre-maiden. This wing is very light but suffers
from flutter at speed. This was the model that I built with the
unsuccessful flap placement.
R/C Soaring Digest