thing you have flown, and can confirm that the incidences, the thrust lines and the CG is 100%
correct, THEN and ONLY THEN, you can go ahead and change the incidence on the stab (and
only the stab) permanently. Measure the trim you needed for perfect level flight at the trailing
edge of the elevator. Then remove the rear anti rotation pin from the plane, adjust the hole,
and re-glue. You will have to change the trailing edge of the stab about the same amount as
you needed trim in your flight testing. (e.g: if you had to trim 1.5 mm down for level flight, you
will have to rotate the whole stab so that the trailing edge comes down this same amount of
1.5 mm, then set the trim to neutral and fly again, to verify. Usually it matches at the first
attempt.)
Last but not least, you should test the balance around the rolling axis. First make sure that
both right and left stab have the same angle of attack, and the deflections of your elevators are
exactly the same on both sides. Then fly and pull up to a loop. Is the plane moving to the right
during the pull, your right elevator might travel a bit more than the left one, or your right wing
might be a little bit heavier than the left one. If it turns to the left, it is vice versa. Please try it
many times, and confirm the direction to which the plane pulls. You might have forgotten even
after your landing. Confirm it several times.
Then do the same thing inverted, and push up to a tight loop (negative loop). If one wing is
heavier than the other, then the plane will now pull to the opposite direction than in the upright
flight (positive loop). If it is indefinite, a slight adjustment on the elevator deflections might be
necessary. If it is clearly pulling to the opposite direction, it will be most likely that both wings
are not 100% balanced.
On a side note, it might be that 2 or more slight mistakes might eliminate each other, or add on
to each other. To find out, you will have to make a lot of “dial in flights”, and you might have to
do the procedure over and over again. If you take your time, you will be granted with one of
the best flying pattern planes of the world, which really is a big advantage in any contest flying.
Composite-ARF IMPACT
34
Standard Hardware and Wood parts included in the IMPACT kit