Well, I decided to wire up my Twinstar II without using the switching ParkBEC (I'm saving it for a plane I want to fly on a 4S lipo pack). To avoid having the BECs in the Thunderbird 18 overheat, I wanted to split up the load, so that one of the two BEC's would power the two aileron servos, while the other powered the receiver, and through it, the rudder and elevator servos. This required some tricky wiring, but I got it figured out.
I will be flying this model with a Spektrum 2.4 GHz DX-6 transmitter, because the Rose Bowl has proven to be a treacherous place to fly with the limitations of our conventional 72 MHz RC equipment. The Spektrum, unfortunately, has only 6 channels, and limited mixing capabilities. So I decided to run both aileron servos off one channel, and also both ESC's (throttle) from one channel, rather than try to set up mixes. That made the wiring even trickier. When I was done, I was staring at this rats nest of wires - three each from two servos and two speed controls, so 12 wires in total, not counting four more wires to feed battery power to the two ESC's (take a look at the attached picture).
The good news? I plugged in a lipo pack, bound the receiver to the transmitter (Spektrum receivers have to be "told" which transmitter to listen to, after which they ignore all other transmitters - hence no more shoot-downs from someone else turning on on your channel), and was gratified to hear the two Thunderbird 18 ESC's beep out the cell count on the lipo pack, then emit the little tune that signifies they were armed and ready to run. I moved the right stick - and the aileron servos moved as they should. I advanced the throttle gingerly - and both motors kicked, then started to spin. Yippee, it all works!
Take a look at the attached pic, and you can see all those bits of blue heatshrink where I soldered wires together. The black rectangular thing is the Spektrum AR6000 receiver - all that mess of wiring occupies only two channels on it, throttle and aileron. The white area below it is the pocket I cut out of the foam wing to hold the receiver and some of the wiring clutter.
Time to head for bed - gotta wake up and go to work tomorrow!