RC India

RC Models => Electric Planes => Topic started by: abhi.vishw on March 04, 2015, 02:28:01 PM



Title: Use of CG?
Post by: abhi.vishw on March 04, 2015, 02:28:01 PM
Hi,
After crashing my Nutball for the 2nd time :'(, i think there is definitely something wrong with it.
Well, in the build instructions it said that the CG is 6" from the leading edge.
By what i assumed is that it is where you place the battery so as to balance the plane as it is the heaviest part. Making the plane tail heavy. :headscratch:
I was still having doubt with what i was doing as the plans and the actual model showed the battery to be very close to the leading edge.
But i didn't read anything else except for CG is used for balancing the plane.
Now i'm getting a clear thought that by placing fingers at CG near fuselage you should try to balance the plane by adjusting the battery position by moving it so it should be exactly parallel to ground.
 
Would like to have veterans advice on this.  :thumbsup:


Title: Re: Use of CG?
Post by: sanjayrai55 on March 04, 2015, 05:54:02 PM
From Wikipedia, the free encyclopedia
"Center of gravity" redirects here. For the military concept, see center of gravity (military). For the precise definition, see centers of gravity in non-uniform fields.

This child's toy uses the principles of center of mass to keep balance on a finger.
In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero. The distribution of mass is balanced around the center of mass and the average of the weighted position coordinates of the distributed mass defines its coordinates. Calculations in mechanics are often simplified when formulated with respect to the center of mass.

In the case of a single rigid body, the center of mass is fixed in relation to the body, and if the body has uniform density, it will be located at the centroid. The center of mass may be located outside the physical body, as is sometimes the case for hollow or open-shaped objects, such as a horseshoe. In the case of a distribution of separate bodies, such as the planets of the Solar System, the center of mass may not correspond to the position of any individual member of the system.

The center of mass is a useful reference point for calculations in mechanics that involve masses distributed in space, such as the linear and angular momentum of planetary bodies and rigid body dynamics. In orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is an inertial frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system.



Title: Re: Use of CG?
Post by: sanjayrai55 on March 04, 2015, 05:55:02 PM
(http://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Bird_toy_showing_center_of_gravity.jpg/640px-Bird_toy_showing_center_of_gravity.jpg)


Title: Re: Use of CG?
Post by: asupan on March 04, 2015, 06:30:14 PM
Another video of the beauty of CG.

www.youtube.com/watch?v=-KVPA-9hofw (http://)




Title: Re: Use of CG?
Post by: Ahmad Ilyas on March 04, 2015, 07:52:24 PM
centre of gravity is the most important thin of object
like in your plane the tail is heavy
some times the nose is heavy
your plane would always is crash if its CG is not correct
if your plane is ft nutball
these video will help you a lot
www.youtube.com/watch?v=00CGAPOp7A0 (http://)
www.youtube.com/watch?v=0LhYonZg6RY (http://)


Title: Re: Use of CG?
Post by: K K Iyer on March 04, 2015, 10:20:57 PM
@asupan sir,
What an example of exquisite balance and elegance...
Only a Japanese can do stuff like this.
Can one of us even think of such a demonstration?

@abhi.vishw
Don't know your age or education level.
But,
I feel sad that you are even trying to fly an airplane without a clue to to the meaning of the CG.
I feel sad not just for you, but for our great 'Make in India' idea
And i wonder how a person capable of making a flying airplane model is ignorant of the CG.

But i am glad that in the last sentence of your post, you found out that the CG is where the plane is to balance...
Now you'll be able to make it fly!
Best wishes
(Bura na man na, mai ek budha hoon)


Title: Re: Use of CG?
Post by: K K Iyer on March 04, 2015, 10:59:28 PM
And one step beyond that.
The effect of removing just one feather...
https://m.youtube.com/watch?v=YrelKDutTyQ


Title: Re: Use of CG?
Post by: sahilkit on March 04, 2015, 11:13:37 PM
Make sure your equipment is fixed, like battery, rx, esc .etc as these will effect CG in flight and make sure rudder is 90deg to fuse/plane body as FT - Nutball plane is very sensitive.



Title: Re: Use of CG?
Post by: abhi.vishw on March 04, 2015, 11:23:40 PM
Thanks for your replies, i should've searched for FT videos on balancing before posting here.
That was informative. :salute:

@abhi.vishw
Don't know your age or education level.
But,
I feel sad that you are even trying to fly an airplane without a clue to to the meaning of the CG.
I feel sad not just for you, but for our great 'Make in India' idea
And i wonder how a person capable of making a flying airplane model is ignorant of the CG.

But i am glad that in the last sentence of your post, you found out that the CG is where the plane is to balance...
Now you'll be able to make it fly!
Best wishes
(Bura na man na, mai ek budha hoon)

I'm 26/BE Electronics.
I'm sorry i deserve what you said...I'm not a born genius by the way.
I have just started with this hobby and will surely learn through.

"Listening to sarcastic people daily will make me more creative" :giggle:



Title: Re: Use of CG?
Post by: K K Iyer on March 04, 2015, 11:43:59 PM
"sarcastic people"
I deserve that, irrespective of how well meaning i may be. Must be a function of my age (62).
The saving grace is that i am at your service should you ever call upon me for any assistance.
Regards.