Trimming:
Chopstick is very CG sensitive, and a balance point
slightly ahead of the mast is usually needed. Too
far forward a location will produce excessive airspeed
and a dangerously fast left turn. I’ve drawn
the tail rotor oversize so it can be gradually trimmed
in diameter until a slow controlled right circuit
is achieved. Good balance is also needed on this
little rotor to kill potential wobbles. Some ballast
on the right skid will also be required to keep
the turn coordinated. Once the basic trim is set
up it never seems to drift off much, and can handle
considerable power variations. If the CG is set
a little rearward the helicopter will fly in square
circuits with little flick turns at the corners
- I’ve really no idea why!
A “ballpark” guess for a motor is a
loop of 3/16” Tan Supersport rubber.
With a slack motor 1.7 times the distance between
hooks “Chopstick 2” should be good for
40 seconds at full turns, though super light versions
(not mine) have reached nearly 90 seconds!
If you love to experiment, this helicopter offers
almost limitless opportunities, including blade/paddle
weights and angles, and CG adjustments in both axes.
This model may be scaled down to any size, and the
plan geometry will still work fine. My friend Bill
Kitching’s 6” span “Matchstick”
flies exactly like its big brother, but on a quarter
of the motor thickness. Graham Stabler holds the
current “smallest” record with a dashing
little 3” version, and is now talking about
the 1.5” option!
“Matchstick” A 50% scaled version
which flies very well. Note the simple but effective
bearing arrangements.
I do hope you enjoy building and flying this little
fellow as much as I have. Many parts (the dirty
looking ones!) of the model pictured are eleven
year old originals!
