Lemon Microbrick Reference Guide
Page 15 of 20
integrated stabilizer) and on to the servo that moves the control surface. For the Lemon receivers, channels 2, 3
and 4 are used, respectively, for the three basic controls, aileron, elevator, and rudder.
Mixing
is the process of combining transmitter inputs to provide the servo output(s) required for control. For
many purposes, the mixing is done in the transmitter. For example, throttle can be mixed to elevator so that as
power is increased, a small amount of down is added to the elevator signal in order to counter the model’s
tendency to climb. Another common mix couples aileron with a small amount of rudder to aid in coordinating
turns. The important thing about such mixes for our purposes is that they don’t affect the basic arrangement of
allocating one channel to each control axis or function. Consequently, they still provide the separate inputs
required by the stabilizer.
The V-Tail and Elevon mixes we are concerned with are different in that they involve two separate and
independently driven control surfaces working together to provide a single aerodynamic function. For example,
a pair of elevons must work in unison to produce pitch and in opposition to generate roll. To achieve this, the
mixing MUST be done on board, since the stabilizer cannot interpret inputs in the form of “mixed” control
commands; it only understands roll, pitch, and yaw.
Any V-Tail or Elevon mixing in the transmitter must therefore
be disabled. Having such mixing enabled in the transmitter when stabilization is active (or having it enabled in
both transmitter and receiver) has been the source of a great deal of confusion for many pilots (and some
accidents).
Flaperon is another case where two inputs (aileron and flap) are involved, but here the mixing is done in the
transmitter.
Let’s take a look specifically at how these three types of control setup are dealt with in relation
to the Lemon
Microbrick. The actual setting of the mix and the indication of what has been set by the 3 blue LEDs has been
described above.
V-Tail
In this arrangement, the functions of elevator and rudder are managed by tail control surfaces that move up or
down together for
pitch
, right or left together for
yaw
.
In the transmitter
tail
type
(if available) is set to Normal; this ensures that separate (not mixed) elevator and
rudder signals are sent to the stabilizer. In the receiver, the second blue LED is on during setup thus indicating
on-board mixing. The two onboard servos are operated by transmitter channels 3 (Elevator function) and 4
(Rudder function.
Elevon / Delta Wing
This arrangement is generally used for a tailless aircraft, such as a flying wing or delta, in which the wing control
surfaces (elevons) are used to control both
pitch
(elevator) and
roll
(aileron). The elevons move up or down
together for pitch and in opposite directions for roll. In the transmitter
wing
type
is set to Normal. In the
receiver, the third blue LED is on during setup thus indicating on-board mixing. The two onboard servos are
operated by channels 2 (Roll function) 3 (Elevator function).
Flaperons (dual aileron channels)
The flaperon arrangement enables the ailerons not only to move in the usual opposite directions to produce
roll
,
but also to move together downward to produce flap action (and possibly upward to produce spoiler action),
thus controlling
lift and drag.
This dual function capability requires that each aileron servo have its own channel: normally channel 2 for right
aileron (RAL) and channel 6 for left aileron (LAL). The stabilizer passes the control inputs sent by the transmitter
through to the two aileron channels. The inputs can include not only flaperon mixing but also differential aileron
