RC India

RC Models => Electric Planes => Topic started by: Harsh17 on December 18, 2016, 05:59:12 PM

Title: Help with balancing plane
Post by: Harsh17 on December 18, 2016, 05:59:12 PM
I made spadet lc-40 with coroplast a week ago.
I maidened it today. It flew quite nicely but it had tendency to bank right.
I balanced its cg but i am unable to balance its wings.
The problem is i am unable to determine the unbalanced point unlike the case of CG when i use my fingertips
Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 18, 2016, 07:42:28 PM
There are many reasons why it could be banking to one side

Ailerons not centred
Stab not straight
Fin not straight
Warp in wing
etc etc

As far as lateral balance is concerned, it should balance about the central axis, that's all. There is no CG
Title: Re: Help with balancing plane
Post by: Harsh17 on December 18, 2016, 08:30:27 PM
So what should i do to determine its cause ??
Will pics help ??
Title: Re: Help with balancing plane
Post by: tahmadblr on December 18, 2016, 09:56:00 PM
It maybe difficult but you may share images indicating the parameters suggested by Rai Sahab.

Not sure it is the case but did you check the approx weight of each wings?
Title: Re: Help with balancing plane
Post by: kiran rc on December 18, 2016, 11:23:49 PM
Quote from: Harsh17 on December 18, 2016, 08:30:27 PM
So what should i do to determine its cause ??
Make sure that the fin is perpendicular to the horizontal stabiliser. Also the stabiliser should look parallel to the trailing edge of the wing when viewed from rear.
Or one of the main cause can be warp as mentioned earlier by Sanjay sir. If the wing has zero chamber aerofoil(flat at the bottom of the wing), you can align the wing on a plane ground to check deformation/warp.
Title: Re: Help with balancing plane
Post by: Aanishp on December 19, 2016, 06:07:46 AM
I have a doubt,
If the motor is exactly perpendicular, then due to the lack of anti torque the plane tends to roll.
I am not sure on the concepts please correct me if I am wrong.


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Title: Re: Help with balancing plane
Post by: Aanishp on December 19, 2016, 06:09:14 AM
So we often tilt the the motor to the right to counter the rotation.


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Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 19, 2016, 06:22:14 AM
Read about gyroscopic moment Aanishp
Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 19, 2016, 06:23:44 AM
(http://image.slidesharecdn.com/unit-7-gyroscope-131127011945-phpapp02/95/gyroscope-13-638.jpg?cb=1415238684)
Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 19, 2016, 06:25:34 AM
To counter this a little right thrust (1-3 degrees depending on the model design) is given

But this does not appear to be the problem of the original poster
Title: Re: Help with balancing plane
Post by: topalle on December 19, 2016, 10:20:28 AM
A video will help to determine the cause.
Title: Re: Help with balancing plane
Post by: Harsh17 on December 19, 2016, 12:49:57 PM
Thank you for all the responses
I'll try to post a video next time as i didn't record it last time
Title: Re: Help with balancing plane
Post by: Aanishp on December 19, 2016, 06:45:18 PM
Thank you
Mr Sanjay rai,it was very informative, I would like to get more of such small but important tips from u.






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Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 19, 2016, 07:17:52 PM
Welcome. But we should not hijack Harsh's thread  ;)

Incidentally, what do you think would be the effect of prop rpm on the gyroscopic couple?
Title: Re: Help with balancing plane
Post by: Aanishp on December 19, 2016, 07:44:30 PM
Actual the first model I brought was an fav rapport for Which the tilt was not noticeable then the second model was the sky surfer(stealth) the motor shaft was tilted by nearly 5-6deg so I got a bout and asked another flyer, he told me the reason it was so as I mentioned above in post #6


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Title: Re: Help with balancing plane
Post by: Aanishp on December 19, 2016, 07:57:44 PM
I have learnt that my mistake in made in my reply was that due to the rpm the effect in the plane was to turn in the nose(rudder movement) and not to roll.


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Title: Re: Help with balancing plane
Post by: K K Iyer on December 19, 2016, 08:05:09 PM
@harsh17,
A simple way to check left/right balance:
Pick up the model with the propshaft in one hand and with a finger under the tail end of the fuselage.
Should balance wings level with muffler removed.
With an upright engine, will be slightly starboard side heavy with muffler, but won't affect flight much.

Check aileron neutrals first, then for warps.

@kiran rc,
Your post needs the following edit for it to be correct.
[/quote]
If the wing has zero chamber aerofoil flat at the bottom of the wing, you can align the wing on a plane ground to check deformation/warp.
[/quote]

A flat bottom does NOT mean zero chamber camber.
Not giving more info here, to avoid hijacking/sidetracking this thread...
Title: Re: Help with balancing plane
Post by: sanjayrai55 on December 19, 2016, 08:13:29 PM
Of course, we all assume that your motor/engine does not have unwanted side thrust

The thread is in Electric Planes, although the Spadet is a Nitro plane  (see http://spadworld.net/forum/viewtopic.php?t=14919&highlight=sanjayrai55 )