Lemon RX Stabilizer PLUS Receiver – Essential Instructions v.1.5
15
Other Issues
IMPORTANT: Don't use Autolevel with Flaperons or Aileron Differential
Autolevel mode on the StabPLUS is intended to help you stay within safe limits and recover from difficult
situations. In using it, however, you must accept some limits on your options. In particular, Autolevel is
incompatible with both Flaperons and Aileron Differential.
The Flaperon function when activated causes dual servos on separate channels to lower or raise both
ailerons, thus giving a flap or spoiler effect. This action involves a significant shift in the neutral settings of
the two aileron channels, something the stabilizer in Autolevel mode cannot properly interpret. As a result,
selecting Autolevel while flaperons are deployed may cause the model to behave erratically. Hence,
flaperons must NOT be deployed when the stabilizer is in Autolevel mode.
Likewise, Aileron Differential is used to improve coordination of turns by reducing servo travel for the down-
going aileron, which limits adverse aileron drag. For example, in a right turn, 50% differential will cause the
left aileron to go DOWN only half as much as the right aileron goes UP. Unfortunately, this can conflict with
Autolevel roll correction and may cause erratic aileron response. Consequently, the differential function
must not be used in Autolevel mode.
Solutions
Flaperons can be used safely only when the StabPLUS is OFF or in Gyro mode. We have provided mixes on
RCGroups for Spektrum transmitters to ensure that Autolevel is not available when flaperons are active.
There’s no problem using two servos on separate channels in Dual Aileron Wing Type, or a Y-cable driving
both servos in Normal Wing Type. It’s when the Wing Type is set to Flaperons that special care is needed.
Similarly, Differential can be blocked in Autolevel mode but allowed in OFF of Gyro mode. To do this, use
the same three-position switch to select Differential as you use for Stabilizer Mode; simply ensure that the
Differential amount corresponding to the switch position for Autolevel (normally Position 2) is set to 0%.
Note that Autolevel provides Gyro-type stabilization on the yaw (rudder) axis, thus helping to ensure
coordinated turns, even without aileron differential. In addition, some models might benefit from a small
amount of aileron-to-rudder mixing, either full-time or only when in Autolevel mode. Alternatively, “old-
fashioned” mechanical aileron differential is very effective and is often easy to incorporate by offsetting
either the servo arms or the aileron control horns.
Using Other Mixes with Autolevel
While mixes other than Flaperon and Aileron Differential don’t generally clash directly with Autolevel, they
should be used with care because the combination can cause significant unexpected reactions. For example,
a throttle-to-elevator mix intended to prevent excessive climb at high throttle may work correctly in Gyro
mode but cause the model to dive suddenly when switched to Autolevel. This is because Autolevel is
already set to keep the model flying level, so the down elevator generated by the mix at high throttle is
interpreted as a command to push the nose down further. A high speed dive is the result.
Some mixes are NOT allowed in Autolevel mode. The technique to prevent use of Flaperons in Autolevel
mode explained in the footnote above can be adapted to any mix to achieve this.
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