Quadcopter Center of Gravity?

rcmike

Member
Hey everyone. I have just put a camera gimbal on the front of my F450 which moved my COG quite a bit forward. Is COG very important for quads? My guess is that the front motors would just have to spin a little faster to lift a little more and balance it all out. I have hovered it in the basement and couldn't tell any difference hovering but I haven't had a chance to take it outside and fly it around yet.
 

Tahoe Ed

Active Member
You did not say what your controller was. If it is a Naza, you are ok, if it is a WKM, then you need to adjust your COG and recalibrate you compass. I would still try and balance you quad mechanically with your lipo. Why make the front motors work harder when they don't have to. It could cause motor or esc failure.
 
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rcmike

Member
Thanks Ed. It is a Naza. I knew I read something about it and it was probably referring to the WKM. I'll see if I can get the COG a little closer to the center though.

Dune, It is this one. http://www.multirotorforums.com/showthread.php?2549-New-GoPro-Tilt-and-roll-gimbal
I
am also using extended skids from IrisAerial. I will have to take a picture of my setup.



Edit: I just checked the COG and it isn't off nearly as much as I thought. I can probably move the battery back an inch or two and it will be perfect.
 
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neavissa

Member
I know this is an old thread, but I am trying to figure out, how to balance a Y6 on all 3 axis?! I have a Vulcan Y6 and a NAZA. I understand that you can put a thread through the hole, in the center on the top frame, you will be able to balance the x and y axis. But how do you balance the z axis?! The only thing I come up with, is to put a rod through the same hole and hand the Multi of a cord... then you move up and down the rod to see where the CG is?! Right?! On the other hand, someone told me that it doesn't really matter where on the z axis the NAZA is?! Is that true?! I am actually not sure if I understood that correctly?! Wouldn't that mean, that if the x and y axis CG is smack in the middle of the frame, you can mount a 3 foot long pole on it and on that mount the NAZA?!

thanks,

G
 

neavissa

Member
Why make the front motors work harder when they don't have to. It could cause motor or esc failure.
Is this actually true?! Sure, the motors would run on different RPM, but why would that be a problem?! One day you might be able to hover at 5000 rpm, and the other day, after adding some equipment, it might take 6000 rpm to hover. So obviously your motors can run all over the place. Why would it now be a problem if your multi is out of balance and the front two motors run at 6000 and the back two run at 5000 rpm?! I dont get it?!

thanks,

G
 

Each motor has a finite speed and torque range.....and those carrying extra load will have a more constrained range.
You will probably find that the MR will lose top end speed or lift at the front before the remaining motors unless you keep the CofG @ the middle of the airframe.


Is this actually true?! Sure, the motors would run on different RPM, but why would that be a problem?! One day you might be able to hover at 5000 rpm, and the other day, after adding some equipment, it might take 6000 rpm to hover. So obviously your motors can run all over the place. Why would it now be a problem if your multi is out of balance and the front two motors run at 6000 and the back two run at 5000 rpm?! I dont get it?!

thanks,

G
 

Stacky

Member
The Ecilop quad has its gimbal set right in the middle of the frame which means the FC has to sit off to one side. Most people using the Eciliop quad are using the NAZA FC.

I know this is an old thread, but I am trying to figure out, how to balance a Y6 on all 3 axis?! I have a Vulcan Y6 and a NAZA. I understand that you can put a thread through the hole, in the center on the top frame, you will be able to balance the x and y axis. But how do you balance the z axis?! The only thing I come up with, is to put a rod through the same hole and hand the Multi of a cord... then you move up and down the rod to see where the CG is?! Right?! On the other hand, someone told me that it doesn't really matter where on the z axis the NAZA is?! Is that true?! I am actually not sure if I understood that correctly?! Wouldn't that mean, that if the x and y axis CG is smack in the middle of the frame, you can mount a 3 foot long pole on it and on that mount the NAZA?!

thanks,

G
 

Dewster

Member
You'll get longer flight times if your craft is balanced. DJI flight controller will try to compensate for uneven weight. You should be able to tell the difference in how your craft behaves after movement. A balanced craft will have smoother flight transitions.
 

neavissa

Member
Thanks for the input everyone! What you guys are saying, about the FC being not on the CG, makes totally sense! However, there is this Hardcore 3D pilot Nick Maxwell and he is actually setting his helicopters up, so they are not level, when the sticks are centered! I forgot why exactly he does it, but it has something to do with the Flybarless Controller being better at keeping a certain position in space than being at zero at all times?! Anyhow, I still don't know how to find the CG on my Y6?!

thanks,

G
 

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