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Help! Twin engine - BEC question

#1
Hi pilots,
I’m building my 1st twin engine, thrust vectoring jet 😍
do I need to programme mix my radio for the 2 engines or can I run the 2 BEC’s off a Y lead
Thanks
 

CarolineTyler

Well-known member
#2
The ESCs can be controlled from the one signal lead via a Y-connecting lead. Be careful about connecting the ESCs BEC power leads together. Typically you take the 5 volts from only one BEC, disconnecting the red power lead of the other BEC.
 

Hai-Lee

Old and Bold RC PILOT
#3
Hi pilots,
I’m building my 1st twin engine, thrust vectoring jet 😍
do I need to programme mix my radio for the 2 engines or can I run the 2 BEC’s off a Y lead
Thanks
Normally for differential thrust, (thrust effected by rudder input), you would need to have a mix or 2 or 3 to achieve it. If you let us know what radio system you are using I am sure someone can give you a step by step procedure that you can follow.

Have fun!
 

Andrew

G'day Mate
#4
If it's a jet with gimbaled thrust vectoring with the outlets close to each other you can use a y-lead or a spare channel mixed to throttle.
Differential thrust very weak when the outlet/thrust very close to each other.

If it's a twin with a motor under each wing your probably wanting to do differential thrust, with minimum of 3 spare mix's and a spare channel.

And which ever way you go, remove the red wire like Caroline described.
 
#5
Thanks for the support pilots 😁

The ESCs can be controlled from the one signal lead via a Y-connecting lead. Be careful about connecting the ESCs BEC power leads together. Typically you take the 5 volts from only one BEC, disconnecting the red power lead of the other BEC.
Cut 1 red wire from 1 BEC ? Why not leave both connected ?

Normally for differential thrust, (thrust effected by rudder input), you would need to have a mix or 2 or 3 to achieve it. If you let us know what radio system you are using I am sure someone can give you a step by step procedure that you can follow.

Have fun!
I’m still using my 6 year old Turnigy 9x 😂 does the job so far
Thought about rudders but probably just go with “Bank n yank” 😂

If it's a jet with gimbaled thrust vectoring with the outlets close to each other you can use a y-lead or a spare channel mixed to throttle.
Differential thrust very weak when the outlet/thrust very close to each other.

If it's a twin with a motor under each wing your probably wanting to do differential thrust, with minimum of 3 spare mix's and a spare channel.

And which ever way you go, remove the red wire like Caroline described.
Homemade jet with homemade TV System 🤪 CR props 6x4
Differential thrust is silly confusing 😁

Some more sanding tomorrow then it’s time for a paint job !!!
Still got electrics to wire up n get CG sorted with battery in place 👍
She’s looking fine so far
It will be Epic either way when I get her in the air ........ for how long is the question tho 😂😂🤣
 

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CarolineTyler

Well-known member
#6
You disconnect one of the BEC's power leads as no two BECs are identical. Connected together the stronger BEC will back feed into the weaker one, possibly causing 'issues'. The rule is that linear BECs can usually cope with being connected together, a switch mode BEC definitely should not be connected together.
So why take the risk?
 
#7
You disconnect one of the BEC's power leads as no two BECs are identical. Connected together the stronger BEC will back feed into the weaker one, possibly causing 'issues'. The rule is that linear BECs can usually cope with being connected together, a switch mode BEC definitely should not be connected together.
So why take the risk?
Hook both up to Y harness, pick one BEC and cut /Disconnect the power wire ?
Thanks
 

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L Edge

Well-known member
#10
Chances are you are overdrawing amperage from the battery. I have a twin transport and I need a minimun of 3300 to keep it going without failure. What rating do you have for the ESC?

I see servos controlling each motor. Did you know if you program your radio it or if you are using elevons, you can incorporate elevator(both motors up) or one motor down, the other up(ailerons) as well as DT. Plane will really become acrobatic.
 
#11
Chances are you are overdrawing amperage from the battery. I have a twin transport and I need a minimun of 3300 to keep it going without failure. What rating do you have for the ESC?

I see servos controlling each motor. Did you know if you program your radio it or if you are using elevons, you can incorporate elevator(both motors up) or one motor down, the other up(ailerons) as well as DT. Plane will really become acrobatic.
Never had the issue before, 3s /2200 Mamp battery, run most of ma park jets on this combo, good to find out other reasons tho,

It 70amp ESC (Red Brick)
I’m using elevon mix with 2 servos @ 3K torque (metal gear) hopefully run 2x2700Kv motors and 6x4 CR props

Tested both ESC on another motor and it worked fine ? Guessing it’s not the ESC, Putting it down to faulty motor? unless I get more suggestions on testing or repair?

Tested engines independently & then both on Y harness.
3s pulses at 1/2 throttle
4s pulse a 1/4 throttle ??
All batteries used were at 100% charge

, Strange that both the motors have failed at same time ?
 

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