Al Masters built the NBP-60 with
the Astro 60 motor drive installed
at the rear, out of harm’s way,
hence the name NBP-60—Never Break
a Prop. He designed it as a challenge
for modelers entering electric fl ying,
but wanting the feel of a fuel-powered
aircraft. The 9-pound, 10-ounce model
featured a 65-inch wingspan. Its fuselage
was designed to hold a maximum of
34 sub-C cells in the front to offset the
23-ounce motor and propeller weight.
The NBP-60 was not diffi cult to build,
but to control the weight, Al needed to
carefully consider the materials he used.
Except where specifi ed on the plans, he
used light balsa with a 4- to 6-pound
density.
The fuselage nose section used
plywood for strength. The fuselage
bulkheads and formers were made from
balsa, Lite Ply, and birch plywood. The
motor mount tube was 12 inches of 1/64
plywood wrapped around the motor.
The tail section was lightweight,
with the upper fi n and stabilizer built
together and 1/16 plywood added after
the stabilizer was removed from the
building board. Hinges were installed
and the complete tail assembly was
covered and attached to the fuselage.
All wiring for the motor was
12-gauge stranded silicone to fi t into
Sermos connectors. Copper braid was
used for the NiCd cell interconnectors.
Radio Shack MS-169 was used for the
arming switch, along with a 30-amp
inline fuse.
The model was designed to use
Spring-Air heavy-duty landing gear
retracts. Al saved weight by bushing the
main struts with K&S brass tubing to fi t
the retract unit with 5/32 struts. The nose
wheel strut was a standard 3/16.
The NBP-60 was covered with
MonoKote iron-on fi lm and Al used
clear MonoKote for the canopy. The
model was fi nished with a Zinger
14 x 8 pusher propeller cut to 13
inches and balanced.
Al noted that the Astro 60 motor
with 34 cells put out plenty of power.
Reduced-throttle fl ights were roughly
10 minutes. Throttle-up aerobatic fl ights
were 4 to 5 minutes. “Getting into the
electric side of the hobby has been easier
than I anticipated,” he noted.
The NBP-60 was featured in the
September 1997 MA as AMA Plans
Service listing 838 and is available for
$24 plus shipping and handling. AMA
members can access the MA Digital
Library on the AMA’s website to read
more about it. See page 151 or go to
www.modelaircraft.org/plans.aspx for
ordering information.
Edition: Model Aviation - 2013/04
Page Numbers: 103
