Hey guys,

Been into rc for years, never really gotten into 3D just liked to watch. Anyway why do some guys or most use 2 rx's to fly the planes? I just read a few posts in Giant Scale where the guys set up list stated he had 2 rx's. Just curious....

Thanks

This was popular a few years back, but I believe most are now going back to a single RX. The theory was that by using two rx's, you could still land the plane if one of them failed. You wire on RX to drive one aileron and one half of the elevator. the other RX drives the other half. put the throttle on either one. If one RX fails, you can probably land the plane (maybe). These big planes usually have two independent elevator halves, each one driven by its own servo. They are mechanically independent.

Receivers are so reliable these days that I think the extra RX does not really add anything. Most of us DO run dual batteries into a single RX. the batteries and switches are more likely to fail than the RX.

I thought the reason was to shorten the wire runs so as to minimize voltage loss. This can be done by one rx controling the tail and the other the nose. Am I totally off base?

You could certainly do this, but you'd end up with pretty long runs to the ailerons anyway. There was another theory about splitting the servo current across two receivers. There was some uncertainty about a single RX being able to handle all the amps from 10 or 12 large servos all flowing through one rx. this turns out ot be no problem either.

Two receivers are also used to share the load when using all the servos that the big 3D planes use like 3 to four servos on each aileron, two to three on each elevator half and four on the rudder.
Most guy's are now using isolator boxes and match boxes to hook everything up. The isolators also let you run 6 volts to the servos and still run 4.8 volts to the receiver.

A lot of people used 2 Rxs primarily so as to reduce the current that gets drawn through each one - there was some concern that with lots of high-current servos being operated with a high duty-cycle, the power bus in the RX could not cope. i.e if one RX was handling X amps, then by using two each would have to handle only a little more than X/2

I've also seen planes with multiple RX's just in there to make life easier. like a multi-engined plane that had a full flight pack in the wings. The result was no wireing to be plugged or unplugged when removing the wings. Just remember to charge both RX packs! (wing RX controlled throttles, flaps, wing mounted retracts, and ailerons. fuse RX controled nosewheel retract, rudder, elevator, and some other stuff)

Lots of differnet reasons to do such a thing.

Although different styles of flying will use dual Rxs for different reasons, In our 3D/IMAC birds there are primarily 2 ,
1 was to handle the high currents of multiple servos. However, if you do a search, it has been shown that a single Rx could handle as many as 60 high torque digitals without failing.

The 2nd reason and the reason that I ran 2rxs' is for redundancy in case one fails. This theory has been strongly debated. I have recently removed my second Rx.