Battery and CG and TakeOff Issues

Having issues with my first quad tipping over on initial powerup. I think it’s
mismatched ESC’s and they will be replaced. All the other usual culprits I think
I have ruled out. Question is this, would a battery that is not installed directly centered in the quad
possibly cause this or am I going up the wrong avenue?


Don’t know for sure but mine is one of those many Alien 450 clones and it as a 3300 4s battery sticking out the back way off COG and it flies nice and level so the controller is quite capable of compensating.

That’s what I am thinking but wanted to hear it from someone else.
I think having one different ESC is messing up the throttle speed and throwing it
off kilter. Have a set of new ESC’s in the mail and hoping that clears up the issue.
Gunning the throttle to get it airborne and then compensating is not the way I want this thing
to function. I want a nice stable takeoff when I add power.

Be aware that ground effect, catching undercarriage, trim bias, etc can make a copter try to move across the ground if you power up very slowly. This usually results in a tip over.

The best way is to “jump” the copter off the ground to a metre or less.
It doesn’t have to be a rocket launch, just a firm lift off the ground.

Hope this helps.

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I agree with @mboland here; “popping” the copter off the ground initially is the best way to get flight started. One to two meters off the ground and let it level out if you’re in a gps assisted mode or in althold. Mine does this also. Like Mike says, it’s probably ground effect. causing this.

If it’s trying to flip the same way every time it could be that your IMU might not be perfectly level. The quad might be trying to compensate for that. Having the COG on a quad is not all that important, all it means is some motor will work more then others but it will fly level either way.

I’ve been dealing with this issue recently with a heavy quad that had an offset COG, and here’s what I found.

a) If it’s offset in such a way that one side “sticks” to the ground because it’s a bit heavier, sometimes popping it helps, but the best solution is to center the COG.

b) In my case, the copter really wanted to yaw, because the COG would try to rotate about the center of the copter, especially when I pitch or roll. Since multirotors are not very efficient at heavy yaw (using rotational torque instead of a tail rotor), this would max out at least one of my motors, while the others were at low power, causing me to lose altitude and control, as well as severe instability during takeoff. Check your flight logs, and see if motors spinning the same direction are being sent higher PWM. If they are, then you may be experiencing this as well.

That being said, my solution was to bring the COG closer to the center on XY and Z (I had a bottom heavy load), which made it much easier for the motors to compensate for the COG swinging around.