Originally Posted by LizardMan
The above is true. However, you must be aware of a feature of their (Spekrum) RX units. The first channel (throttle) is special. When the RX isn't receiving a usable signal the RX enters a fail-safe mode, it drives channel #1 (throttle) to a low value. The other channels will either stay at their last value or move to a pre-set value depending on the RX model and/or fail-safe mode set during TX/RX binding.
Two things will happen during a hold/lock-out condition. First, whatever you plug in to the throttle channel will be driven to one end of its travel (full down flap/aileron/spoiler.) Second, the motor (plugged in to the gear channel) will not power down like it would if it were plugged in the throttle channel. This could create an unsafe condition; motor on and control surfaces in extreme positions.
I leave the motor/ESC connected to the throttle, and use throttle cut/hold to temp disable the motor. The same switch both disables the motor and enables a mix mapping throttle to flaps/spoilers. During launches the flap/spoiler mix is disabled and motor is enabled. At the top of a climb out flip the switch disabling the motor and enabling the flaps/spoilers mix. Works for me.
Thank you, LizardMan, for so clearly describing the weaknesses of the Spektrum "Smart-safe" system. I prefer to call it "dumb-safe". With all but the high-end receivers, an interruption in the signal causes the throttle channel to go to zero (good) and all the other channels "remember their last position" (bad). That means the smart safe does nothing to the other channels, which is definitely dumb. At least with the old DSM2 systems, a pre-programmed setting would take over.
If you are willing to pay extra for a high end receiver, you can have it too, but that is beyond the capabilities of the receivers that come stock in any of the Parkzone planes. Using the throttle channel for any other purpose is done at your own risk.