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Old 10-20-2012, 03:05 PM   #17
pmullen503
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Originally Posted by solentlife View Post

The ESC / BEC question ... I have no worries unlikje some about linear BEC's .. never had a problem so far. I've run and do run 5 servo machines of 3A .. 5A BEC's ...
But here I will be running possibly 9 servos + 2 servoless electric retracts. That's a lot for a single BEC, separate or not. So I want to see about using more than 1 BEC from the ESC's ..

1 dedicated for the retracts just in case of stalled leg !

the remaining servos divided up among the remaining 3 BEC's ... ie 3 servos each.

How to wire them up ? Is it connect red leads direct to BEC's and only one red to rx ... with signal and grounds common ?
Is it better to have separate Rx power pack with servos powered independently ?

Anyone done this ? I bet others are interested if they do multi motor jobs ..

Nigel
I'm not aware of any simple, cheap system for pooling the output of several linear BECs. Just connecting all the red leads and grounds guarantees that only one will take most of the load. It's cheaper and simpler to just use a high capacity switching BEC or a receiver battery.

You can use an second receiver to simply split up the loads. Say, retracts, flaps, and two motors hooked to one receiver taking power from one of the ESCs. Ailerons, rudder, elevator and two motors on the other receiver powered by a proper UBEC. That way a gear jam that takes out the entire second system only takes out flaps and two motors. The onboard BEC can easily handle the retracts.

I've used multiple receivers to ease assembly by putting one receiver in the wing and one in the fuse. That way, all you need to do is make a single power connection when assembling at the field. With compatible receivers for many systems so inexpensive, it sometimes costs less to add a second receiver than to buy the servo extensions!

I went the thin flexible push rod route to do the twin rudders on my Beech D-18. The idea of burying the servo arms in the rudders is interesting but I'd be concerned about maintenance and adjustment.

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