PROJECTS: FLYING WING
Channel 1
(right servo) G
A
LITTLE WING
The Towel is a flying wing — a fixed-wing aircraft without a fuselage or
separate tail structure. Like Northrop
Corp. and Germany’s Horten brothers, we found advantages in its
simple and strong construction.
I
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L
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E
G
G
A Flight is steered by 2 independent
elevons on the wing’s trailing edge,
rather than the separate elevator and
ailerons used in traditional planes.
K
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10 11 12
Channel 2
(left servo)
H
B The airframe is cheap, rugged
polystyrene foam that’s easily replaced.
I
C The detachable deck holds the
motors and electronics.
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J
4
12
M
12
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D The radio transmitter sends
control signals on 3 channels: throttle,
aileron, and elevator.
G
C
B
E The radio receiver relays the
signals to the onboard electronics.
F The elevon mixer (onboard or in
the transmitter) blends the aileron
and elevator signals to coordinate the
2 elevons.
I The throttle signal governs the
electronic speed controller (ESC),
which provides AC power to the motor,
and also powers the receiver and servos
through its battery eliminator circuit.
(RD) or “slow-flyer” type. Together
with the outrunner motor, it provides a
powerful 1: 1 thrust-to-weight ratio.
J The outrunner motor is a brushless AC motor that spins its shell
around its windings, for low speeds
and high torque without a gearbox.
L The prop saver holds the prop on
the shaft with an elastic O-ring so it
can detach (not break) in a crash.
G Two servomotors move control
rods to raise and lower the elevons.
H Twin vertical stabilizers help the
plane track straight without yawing.
K The propeller is a reduction-drive
M The LiPo battery pack powers
6–7 minutes of flight. Its placement is
adjusted with velcro to fine-tune the
plane’s center of gravity.
4 CHANNEL R/C
AIRPLANE
4 CHANNEL
R/C Throttle Elevator
Rudder Aileron
3 CHANNEL R/C
ELEVON PLANE
Elevon Mixer
ELEV
AILE
–+S
–+S
Ch. 1
Servos
Ch. 2
Most R/C planes have 3
servos, for the ailerons on the
wings, the elevator in the tail,
and the rudder. A flying wing
has 2 servos, for each of its
twin elevons, but there’s no
rudder. This requires elevon
mixing by a microcontroller.
» Aileron signals govern roll.
The mixer pushes/pulls the
elevons in opposite directions.
» Elevator signals govern up/
down pitch. The mixer raises
or lowers the elevons together.
» Rudders govern left/right
yaw in a 4-channel plane, but
the Towel’s big stabilizers
eliminate the need for one.
Rob Nance
84 Make: makezine.com/30 makezine.com/30
