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Twin Engine ESC & Engine Questions

Old 03-12-2018, 02:58 PM
  #1  
Vinny7636
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Default Twin Engine ESC & Engine Questions

Hello to all,
I could use some help please with Engine & ESC selections.
I have a wooden kit, twin engine Cessna Bobcat, 85" WS, it should end up approx 17 to 25 lbs.
Being a twin engine model I am reluctant to power this plane with twin gassers. I have 2 zenoah g23's but feel this AC would live longer on E power,

Attached you will find a simple schematic with my calculations after doing some research. You will find that I have 1 ESC controlling both engines, I was going to use 2 separate ESC's, but I have an Hobbywing 150A OPTO and would like to use it , not sure if this will work?

?
1 Estimated Flying time with 2, three cell 5000 mah batteries?

2 Will power distribution to engines be balanced with this set up? Anybody tried this before?

3 If I use 2 ESC's, would two 80 amp ESC's suffice with the Turnigy engines selected? If not is there any balancing devices or different wiring I can use?

3 With twin AC can you split the wattage by 2? Therefore an AC requiring 2000W, you can power it with two 1000W engines.

4 Do you think the Turnigy engines I selected will give this AC a medium performance?

I greatly appreciate any input and your time...

Thanks to all, Vinny
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Old 03-12-2018, 05:30 PM
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Some say it can be done, but others will warn it can mess up the timing of the motors, or fry the ESC.
I built a twin using two 3s lipos connected in parallel, with two ESCs connected to the Rx with a Y harness, and it worked great. To keep the motors in synch, I made two extension leads pretty much the exact same length.
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Old 03-12-2018, 05:40 PM
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Vinny7636
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Cool, yes I'm heading in that direction using 2 esc's. I have the one, 150a esc and wanted to us it, but they no longer manf. that model.

thanks, vinny
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Old 03-12-2018, 07:09 PM
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firemanbill
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I have never seen anyone be successful running two brushless motors on one ESC. Not saying it can't be done, I just have not personally seen that work.

I had a Eflite EDF Airiner and used two separate ESC's and SQ said, tried to keep the leads all about equal length.
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Old 03-12-2018, 11:33 PM
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Originally Posted by Vinny7636 View Post
Cool, yes I'm heading in that direction using 2 esc's. I have the one, 150a esc and wanted to us it, but they no longer manf. that model.

thanks, vinny
Not sure what motors you intend to use, but HURC sells some 100 amp OPTO units that are very affordable:

http://www.headsuphobby.com/Sky-Powe...EC_p_1815.html
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Old 03-13-2018, 01:42 PM
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solentlife
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One ESC will not run two motors properly.

If the two ESC's have BEC's built in - linera BEC's are fine both working - but SBEC's are recc'd not to be both connected ... pull red lead of one ...

(I have connected both SBEC's on my Concorde and TU144 models without problem).

I have twin models with parallel and separate batterys ... of course parallel should be better so that both motors reduce together due to battery power going down...

Its also worth thinking about differential throttles ... basically both controlled by one stick .. but rudder altering the motors to create a yaw effect .. my Lancaster has it (ok its 4 motor but principle is same) ...

Nigel
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Old 03-13-2018, 08:33 PM
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Vinny7636
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Originally Posted by solentlife View Post
One ESC will not run two motors properly.

If the two ESC's have BEC's built in - linera BEC's are fine both working - but SBEC's are recc'd not to be both connected ... pull red lead of one ...

(I have connected both SBEC's on my Concorde and TU144 models without problem).

I have twin models with parallel and separate batterys ... of course parallel should be better so that both motors reduce together due to battery power going down...

Its also worth thinking about differential throttles ... basically both controlled by one stick .. but rudder altering the motors to create a yaw effect .. my Lancaster has it (ok its 4 motor but principle is same) ...

Nigel
So being a novelist with twin E's, I am assuming that you mix throttle and rudder? How do you program that or do you hook esc in different channels on the Rx? Would your rudder trim be used as a balance?
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Old 03-13-2018, 09:15 PM
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Originally Posted by Vinny7636 View Post
So being a novelist with twin E's, I am assuming that you mix throttle and rudder? How do you program that or do you hook esc in different channels on the Rx? Would your rudder trim be used as a balance?
Answered other thread.
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Old 03-14-2018, 07:02 PM
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Originally Posted by Vinny7636 View Post
So being a novelist with twin E's, I am assuming that you mix throttle and rudder? How do you program that or do you hook esc in different channels on the Rx? Would your rudder trim be used as a balance?
Use a V-Tail mixer hooked to throttle and rudder.

I have flown 3 planes with twin brushless motors on a single ESC that worked but these were low kv and less than 10 amp draw. I would not recommend it and here why. Both motors seem to start fine and work but in the air closing the throttle and restoring power at times you would get one motor cogging or stuttering. While it was just a matter of hitting the throttle again to make them sync its really not something you want to deal with while flying.
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Old 03-14-2018, 07:34 PM
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ron_van_sommeren
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Two active threads, same subject.
Continue in the thread with most replies?:
Twin Power Question/Help 85" Cessna Bobcat Build
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