I have been out of the hobby for about 6 yrs. The big 3D planes are running two receivers, is this a form of redundancy for saftey or is it functional installation please help me out on this I am curious. Thanks a bunch!

POWER

There are a few differing opinions on using 2 revceivers. Most large planes seem to use them however for the following reason:

1. To give some redundancy to the system and use half the plane on one and half the plane on the other (left and right).

2. To give more places to plug servos into and split the voltage load to the servos.

EXCAP232

Is it always left and right, or can it be servo #1 on rx #1 and servo #2 on rx #2 all on the same control surface like an aileron?

Typically, you don't want to split a control surface across two receivers. If on receiver fails, or commands a failsafe, the other receiver would then be effected. Basically, it will be fighting against the servo that is in failsafe, and can lockup both servos, drain the battery on the good receiver due to the high current drain of a stalled servo, or possibly break the linkage in some way.

The following is something that I have written on the use of dual receivers. I tried to cover all the bases;

http://webpages.charter.net/mediasho...cal%20main.htm

Sorry, forgot to answer the other half of the question.

No, it doesn't have to be left and right only. In fact, in my opinion, its best not to to help alleviate any adverse effects of only half the surfaces working. Here is how I setup the dual receivers in my planes.

Receiver 1 Receiver 2
Aileron Left Ail Right Ail
Elevator Right Elev Left Elev
Rud Rudder
Smoke Smoke
Kill Kill switch
Throttle Throttle

If receiver 1 fails, I have the right aileron and the left elevator. I fell this is better than having the left aileron and left elevator. Easier to counter any adverse differential motion.

Further, if either receiver fails, I have some control over the motor. I can either operate the throttle and kill the engine, or just kill the engine. Either way, there is some control. If the rudder fails, no biggie, just fly it (as long as its not hard over).

This setup also seems to balance the battery load, as the drain on the batteries always seems consistent to each other. The setup has been working in the last three 40% planes without any issues over the last few seasons.