Hi Everyone Hopefully This Thread Will help others out there in Setting up Their Multi Motor Powered Aircraft, I Know I ran into issues with a twin Motor Plane that drove me Crazy trying to figure out the problems, Hopefully this Thread will Point people in the right direction to get it Right the first time, Please add any info that will help Others to Succeed in getting their Multi Motor power system set up Correctly.
Thank You Everyone.
I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
a) Regardless of motors - use SAME ESC brand and power range based on the highest power motor in the set.
b) Linear BEC's can all be connected without problem and in fact will allow a greater amp load to be covered. No need to isolate down to one only.
c) Switching BEC's cannot be all connected to one Rx ... they interefere with each other - and you need to isolate all but one ... leaving one only to power Rx. You could fit a 'battery-backer' and have another BEC connected to that - then in event of first BEC failing - the BB will auto switch instantly to the second BEC.
d) It is generally advised to have props contra rotating to cancel out torque - BUT it is not essential and as long as both motors are running same - you would not know difference.
e) Many twins in model form will not fly single engine out ... it takes too much rudder / yaw authority to do it well. You may be able to fly a low speed descending landing pattern though.
f) Twin's do not mean double speed. You are still limited to PITCH speed ... but your acceleration should be better. What you may get is a small increase in speed as the twin set-up will reduce drag losses by way of increased power.
Here is what I have learned so far from my Mistakes.
1. Use ESC from the same vendor, and same Amp Value.
2. Use Motors from the same Vendor, same size and KV.
My DO-335 has two different size motors and two different ESC's. Only one has a BEC. That setup has worked fine for years. The problems you had with the Cessna were weird. But for side by side twins, use the same motors and ESC's. If you are running more than a couple servos or more than 3s, use a switching BEC. Most linear BECs have a limited capacity.
You can separate and reduce the loads on linear BECs by running two receivers with separate circuits. I've used a pair of cheap Spektrum clones (DSM2), one in the wing and one in the fuselage to simplify assembly and disassembly. Just run one of the throttle connections to the second receiver for power.
Contra rotating props help especially with ground handling for tail dragging twins and with aerobatic aircraft when trying to get matching right and left roll rates.
Many TXs can handle differential thrust programming on two motors. This is great for seaplanes and tail dragging twins when taxiing.
For what it is worth I set up my multis so that the prop tips on either side turn into thecockpit. Dont know where I got that idea done it for years even back in my free flight days. Oh yes, I set up the left snd right inner motors on one setup and the left and right outers on another.