RC India

Hello everyone out there, i have build my own scratch model of a twin motor rc plane with the motors having same specifications and same manufacturer but what i see is my plane is turning towards right side.....is it due to different thrust or something else. I am new with the twin motor planes....please help me out.

The propellors should be contra-rotating. ie, both rotating towards each other

See http://www.rcindia.org/electric-planes/'2016-sweepstakes'-electric-challenge-twin/

Yes sir i have installed the counter-rotating prop....but then also the plane is going towards the right side. I am unable to understand the problem sir. Please help me out.

Put some photos

Sorry for the delay sir. Here are the photos.

Sir I have tried both the configurations i.e. propellers rotating towards one another and rotating away. But nothing is working out.

I can't make out too much from the photos but please check and revert on:

1. Are the props contra-rotating? ie one CW and one CCW
2. Check lateral balance
3. Is Fin square (90 degrees) with stab?
4. Is wing parallel to stab
5. Are both motor's axes parallel, and square with wing

From the first photo it appears

1. Fin is angled
2. Both motors are pointing outwards ie Toe-out
3. The wing and stab are not parallel


BTW: the third motor? To lift the tail? Why?

Sir ... this is a advanced VTOL plane .... initially it will be tricopter. ( Good design )

@ Chandra - please tell when is your plane going right in air or on ground or while hovering?

You must be having serious issues with CG. Even if you are balancing CG at 30% of wing. I am sure the total weight of your plane must be high.

regds
Saurabh

Whatever it is, if toe-out and fin inclined how is it going to fly straight?

You are right sir that is very much essential for plane to fly straight.

But i am expecting revert from Chandra.... If he is able to take it off the ground then with that skill he wouldn't be asking this question.

It is too complex idea to implement & if someone implements it, then flying straight is a simple task.

Why so roundabout? Are you Chanakya?

He had a problem, so he asked for help. You should help him, not take his exam  :D

@sanjay sir, i have checked everything. It may be true that my motors are toed out up to some degree (i will surely take it into consideration) , but still when i'm holding the plane in my hand i can feel different thrust on both sides of the plane. As far as the vertical stabilizer is concerned, it is straight because it flew a couple of times in regular flight mode. My both motors on the wing are of same configuration but still the thrust is different. The propeller is a couple of 8X4.5 (one is CW and another one is CCW).

The third motor is to lift the plane vertically up as told by the saurabh sir in order to pitch control. The weight in the aft portion is troubling me a lot but it is able to lift the plane a little bit from the tail. I also think that two motors only on the wing for a wingspan of about 1300mm produces slight less thrust in order to lift it off. But primarily i'm unable to control the thrust difference by the two motors. My plane goes directly toward the right side. One thing is to be noted that i have not installed any flight controller here, everything is direct i.e. signal receiving directly from the Rx.   

@saurabh sir, yes sir balancing cg is a very tough task in it because the aft portion is having a metal gear servo of about 70-75gms plus the weight of pitch control motor. The electric ducted fan will work fine i guess. Despite of that i have lifted off it from the ground and attained a height of somewhere about 2-2.5m. If there will be two more motor on the wing then it will surely lift it off the ground. The metal gear servo installed here pulls the wing to a near vertical position (not fine vertical i.e. 90 deg but somewhere about 75-80 deg). Once it lift-off the wing will come to normal flight mode.

P.S.: I have modified the metal gear servo to increase the arm throw from near 110 deg rotation to nearly about 180 deg rotation.

vertical stabilizer is concerned, it is straight because it flew a couple of times in regular flight mode

What does this "regular flight mode" mean?

but still when i'm holding the plane in my hand i can feel different thrust on both sides of the plane. As far as the vertical stabilizer is concerned,

If you can "feel"different thrust being developed by the motors, then obviously something is wrong! What is the system for connecting battery to ESC/Motor? I presume you have connected in parallel. Have you tried checking input V/A to each motor?

Try calibration of Esc.  It can be a issue that at particular throttle position both esc  are not getting same signal.  Esc calibration can solve that.

@sanjay sir, sorry for terms i used sir, by regular flight i mean to say flying straight.
Sir, i have connected both the ESCs with a Y- cable by pulling out the red wire of one of the ESC.
You are right may be one of the motor is getting delayed signal like delayed by 2-3 sec, but how to fix this out?
As far as the power supply is concerned, i have made a harness that connects the battery with all the three motors, surely all the positive at one end and all the negative at another end.

@sanjay sir, please help me how to check V/A supply to each motor.

@saurabh sir, ok sir i will try calibrating the ESCs.

Use a multimeter

Calibrating the ESCs have solved my problem. Thanks a lot for your suggestions sanjay sir and saurabh sir.

 :thumbsup:

Nonetheless,do try and address the other issues if you can. The model will fly better

 :bow: Sure sir