The radio compartment with 8S flight battery,
smaller radio battery, and new rudder servo
after the BEC was removed.
LiFeSource receiver pack. This rudder
servo needed to be swapped for one
rated at 6 volts.
A 2.15-ounce Turnigy TGY-9150MG
servo replaced the Futaba S9151. My
International Miniature Aerobatic
Club (IMAC) friends claim the TGY-
9150MG is a brute on 6 volts. A Castle
Creations BEC weighs roughly the same
as the weight difference between the
heavier Turnigy and lighter Futaba servo,
netting close to zero gain/loss.
A 1.44-ounce Zippy 700 mAh
LiFePo4 battery receiver pack replaced
the 2.7-ounce 1, 100 mAh LiFeSource
receiver pack to reduce weight by more
than an ounce. If used, a 700 mAh
redundant battery system setup would
have approximately zero weight gain/
loss and is a future consideration.
Experience has shown a typical
electric Pattern flight uses anywhere
from 50 to 75 mA, theoretically making
a 700 mAh receiver pack good for eight
flights: 80% of 700 mAh capacity, 70
mA multiplied by eight flights. My
practice is to charge every six flights.
I had every intention of replacing the
aluminum stabilizer tube. I removed
the stock aluminum tube and cut the
new carbon-fiber tube to length. Big
surprise—both tubes weighed the
I had inadvertently purchased a
thick-walled 10mm carbon tube
instead of a lighter, thin-walled
version. With zero weight savings,
the aluminum tube was reinstalled
before leaving the workshop for the
evening. Using published weights, the
substitutions shaved a respectable 4. 21
ounces from the airframe.
Finally, I swapped the 21/2-inch
plastic review spinner for a 21/4-inch
transparent one. The smaller-diameter,
transparent spinner is my preference.
It’s slightly lighter, allows direct motor
cooling, and I like the look!
Spinner/propeller weights are not
110 Model Aviation MARCH 2015 www.ModelAviation.com