Carl Goldberg GBGA0067 - Manual (Page 38)

FLYING THE SUKHOI
The CARL GOLDBERG PRODUCTS SU-26 probably
flies more like its full-size cousin than any other kit on
the market. We have designed it deliberately to make
unlimited aerobatics practical for the average pilot. In
fact, if you are comfortable with a low-wing sport air-
craft, you should have no difficulty in being successful
with the GOLDBERG SUKHOI. Take great care in
building and setting up your aircraft and the SU-26 will
reward you with many hours of exciting aerobatics.
THROWS
We have provided two sets of throws. It is highly rec-
ommended that you start with the lower throws and,
after a few flights, work your way up to the higher set-
tings, if you desire. If you are using a computerized
radio, always use the highest percentage possible and
then mechanically adjust for the proper throw. Also,
because of the high deflection and generous area of
the control surfaces, it is recommended that you use
exponential to soften the feel around neutral. At the
lower control settings, little, if any, expo is needed. Try
15-20% at first and, for the higher settings, try about
40% for all controls. These settings are only sugges-
tions and may be modified "to taste."
ENGINES
This SUKHOI was designed around the .90 two-stroke
and the 1.20 four-stroke engines, which will yield
excellent performance. . The secret is to not build too
heavy. Remember, a bigger engine is not better, as it
adds weight, vibration, etc. Therefore, DO NOT use a
larger-than-recommended engine, which could result
in structural failure of the aircraft. As for props, we
have found that a 15-8 to 16-8 propeller and a proper-
ly sized spinner seem to work well on these engines.
FIRST FLIGHT
Double and triple check that all is in order...extra time
here is always well spent! When satisfied with con-
trols, engine response, etc., you're ready.
When taxiing, we recommend you always maintain full
up elevator, especially when flying off grass. Point the
nose into the wind and gradually apply full power. As
the SUKHOI accelerates, reduce the elevator setting
so that, when the aircraft is ready to fly, you will have
just enough up elevator to rotate and climb out at a
shallow angle. Also, during the application of power,
due to engine torque, the SUKHOI will veer to the left,
so be prepared to hold some right rudder. In all prob-
ability, no more than 10-20% rudder input will be need-
ed, and this should be maintained during the initial
climb-out. This take-off technique is not only best for
the SUKHOI, but is the proper way to take off any air-
craft, particularly a tail-dragger.
Once in the air, the SUKHOI should have a fairly bal-
anced feel. Rolls will be relatively quick, but very pre-
dictable, and pitch is very positive, but not too sensitive.
Inverted flight takes a small amount of down elevator to
sustain. The rudder is large and powerful, which makes
"stall turns" a breeze and "knife edge flight" a pleasure.
On our prototypes, we did not require any mixing to
compensate roll. The nose did pitch up ever so slight-
ly, but we did not feel it necessary to "dial" it out with the
radio. Snap rolls are very quick and stop instantly. A
note on snaps: you don't need high rate rudder and
elevator to get the SUKHOI to snap properly. If you do
that, the aircraft simply goes deeper in the stall and
decelerates rapidly. Normally, this is not a problem, but
if you try to snap roll on a vertical up-line, it can almost
stop the aircraft. If you snap with low rate, the SUKHOI
will continue to climb cleanly.
Lomcevaks are an absolute delight with the SUKHOI. It
seems to do all variations well, including one in partic-
ular. From level flight and full power, pull up about 60º,
roll right 90º, then snap inside left and, after about one
full rotation, apply full down and opposite aileron...then
hang on! Almost always, you can execute two full tum-
bles...and sometimes more.
Landing the SUKHOI offers no real difficulties.
Because of the low wing loading, it can land very slow-
ly, but be aware of the long landing gear and try to get
most of the "fly" out before you touch down. If you hap-
pen to touch down with too much airspeed, be prepared
to release some of the up elevator to prevent the air-
craft from bouncing back into the air.
REMINDER
As good as this SUKHOI is, all aircraft have limita-
tions and this one is no exception. Using care and
common sense will help ensure the survivability of
your aircraft. And, of course, always think and fly
safely.
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