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help with first twin setup

Old 06-22-2009, 09:14 PM
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jt182
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Default help with first twin setup

I am doing my first twin what is the proper way of wiring up the motors and esc.
20 amp esc the motors are emax cf2822 any help is greatly appreciated. I have heard that you need to cut one red wire on the esc to kill the power to it . do you have to program the esc a special way. and should you make sure to test each motor that they are rotating the same way before the final connections.
Thanks for any and all replys.
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Old 08-06-2009, 01:10 PM
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Dangaras
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Default RE: help with first twin setup

There are a few considerations;

1. are you running both ESCs off 1 or 2 batteries?
2. are you running the ESCs of a Y-cable from the throttle channel or are you slaving an unused channel to the throttle channel?
3. are you running the RHS motor clockwise or both motors counterclockwise?
4. 2 or 3 blade props?


1. If you choose one battery, then the motors will most likely run at close to the same RPM. That is if the ESCs and motors are closely matched. Different batteries can introduce a different RPM value on one or the other and cause your twin to "pull" left or right. This speaks for using the slaved channel option. If you can get one 'fat' battery into the main body that is way better in terms of usability & safety than having to get at the nacelles to install 2 batteries.

2. No matter what you do for power, one of the ESC BECs will have to be disabled or disconnected. That means removing the red wire from whichever one is not going to power your receiver. That or you remove both ESC red wires and use a receiver flight pack. Either way, don't cut the red wire on the ESC, use a cheap extension cable and cut the red wire there, allows you to use the ESCs elsewhere if you move on to another model.

Also when connecting the batteries, connect the one with the disconnected BEC first, then the one that powers the rx second, that will initialize the ESCs together. Do remember to configure the ESCs (if doing so with your TX & RX) before disconnecting the BEC wire, it's a real pain to go digging around in the wings after everything is all assembled. 

If you use a Y-cable off the Throttle channel to run both ESCs you most likely will find that the model will fly well with some minor pulling, I used a tachometer to determine which was at a higher RPM and used that knowledge to help me "remember" what trim was required on the maiden flight. I found it quite manageable and never changed to slaved channel until I went to 3-blades and counter rotation.

3. I got my hands on some master airscrew 3 blade 8x7 pushers for the RHS motor. In order for this to work properly, I switched the RED & Yellow (my motor's wire colours are red, yellow & black) wires to get counter rotation  (clockwise rotation looking from the front). Then I tested the RPMs and noticed the difference was the same. On my first flight with the new props I really had to push up the throttle to get the similar performance. This really cut my flight time. As opposed to flying for 10 mins now I can only reliable get 6 mins.

My configuration DX7/AR7000,  3 cell, 1500mAh LIPOs in each nacelle (I sometimes parallel two of these in each nacelle), 40  amp ESCs & 1100KV AXI type outrunners. I also noticed a pronounced pull to the right that was not there before.

I also uncovered an odd behavior, the counter rotation motor would stall occasionally on my takeoff run. I had to do a few static full throttle "warm ups" before the problem went away. I can still hear the motor 'missing' when I throttle up from zero.

To deal with this I have gone to the throttle slave route. I am all connected and preliminary testing looks positive I am planing to test the configuration tonight to determine just how much tweaking I need to do to get balanced RPMs through the entire range.

4. 2 blade props like 9x7 will give you far better efficiency than 3 blades like my 8x7. I however, like the look of the 3 blades and the counter rotation...
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Old 09-28-2009, 07:48 PM
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Default RE: help with first twin setup

Thanks for posting.. I just ordered a twin Beachcraft Baron... should be here in a month or so, and I have no idea how to set up the twin ESC's!
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Old 09-29-2009, 08:29 AM
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Default RE: help with first twin setup

Take a look at the following thread. It will give you support and all the little things you need to consider.

http://www.rcuniverse.com/forum/m_87...tm.htm#9053598
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Old 09-29-2009, 08:54 AM
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Default RE: help with first twin setup

Thanks. I'll be using (probably) a 5s 3400 mah setup to drive twin Power 46 motors. If there's room in the nose (supposedly there is) I may tie 2 5s batteries in series just to get some reasonable flight time.

I like the idea of counter rotating props, we'll have to see how much thrust angle is built into the nacele mounts and go from there.

Always something to learn in this hobby!
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Old 09-29-2009, 12:44 PM
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Default RE: help with first twin setup

I have to adjust my Nitro-P38motor mount using washers to get my motor to point down and to the left, opposite of the usual for counter rotation. I do have an e-flite p38 that was designed with counter rotation as the norm. Hence the down-left is already built in...

What size is your plane? Just make sure the weight of the 2 batteries isn't excessive and exceeds the wing loading.

My Nitro P38, 52.5" wingspan uses 2 x 3Cell, 1600mAh LIPOs in ache nacelle. The final flying weight is right around 5 lbs. I can get 12 to 14 minutes of gracious flying with careful throttle management.
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Old 09-29-2009, 01:08 PM
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Default RE: help with first twin setup

It's a 74 inch plane, should come in around 11 ot 12 pounds.
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Old 09-29-2009, 01:44 PM
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Default RE: help with first twin setup

Ok, Iam finishing a H9 - 0.60 size F4U Corsair and Iam using a hefty "TGY AerodriveXp SK Series 50-55 580Kv / 1580w" motor to run it.

http://www.hobbyking.com/hobbycity/s...idProduct=7071

It should have a flying weight of 8.0 lbs.. Iwould guess you need 2 of these or something at least 75% smaller as you will be running both at slightly less than 3/4 throttle for takeoff (hopefully).

I was very lucky with my motor choice for my P38, Iam using 2 x 1100KV motors that are around 480W each, Irun them with 40A ESCs and during the course of the summer, one of my motors would quit right in the take off range or during 2/3 throttle filght. Iquickly learned that Icould successfully fly and land on only 1 motor!!!!!

Spending the little extra $ for the safety margin saved me a whole lot of heartache and having to rebuild...
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