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Electrohub CG

#1
Hello,

I have finish my electrohub build with the flip 1.5.
My first flight test was not a success. The MultiRotor tip forward and broke one of the propeller.

I just received the replacement propeller and I was testing it slowly by adding power to the electrohub a little at a time until it almost takes off. It will turn a little and tip forward some before almost taking off.

I wanted to test if it is out of balance or CG is off. Is there a CG on the electrohub?
I have the camera/battery mount on it, not sure where to adjust the battery location. I do not have a camera on it now.

also I notice one of the motor is hot compare to the other three. Is this normal?
 
#2
For checking your CG simply place a finger under each side of the quad and lift, move your fingers and/or battery until the quad balances... that is where you want your FC to be, or as close as possible.

On take off try to quickly pop the Quad up to about 3 feet. If you slowly throttle up on take offs the prop wash and air deflection off the ground will throw off your FC, and can even cause extreme tilting.

Although trimming is likely needed, a slow take off may give you the impression something is wrong with your quad, when in fact it's dialed in.

(Note) I post this reply assuming your build, settings, and configurations are correct.
 
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#3
Is there certain holes on the side to balance by?

(note) I hope that I built it correctly, I do not have anyone to tell me or not,.. lol
I followed the best I could with the Quad for dummies on the ready to fly quads website.

I also have another question about the command on radio to disarm motors.
I am able to enable the motor and see the blue light come on by moving rudder stick all the way down to the right
but when I try to disarm motor by moving the rudder all the way down to the left it does not disarm,...:confused:

same for to level reset, I do not see the light flash.
I do see it for accelerate reset.
 

stay-fun

Helicopter addict
#5
Please do check if the quad is stabilizing in the right directions. Take your props off (!), arm it, go to a quarter to half throttle, and move your quad. Drop every arm, the motor on that arm should start spinning faster (trying to compensate).
 
#7
Please do check if the quad is stabilizing in the right directions. Take your props off (!), arm it, go to a quarter to half throttle, and move your quad. Drop every arm, the motor on that arm should start spinning faster (trying to compensate).
Yes, the motor speeds up when I lower the arms, also it sounds like one of the motor slows down.
 

C0d3M0nk3y

Posted a thousand or more times
#8
I am trying to figure out how to balance the electrohub.
When I pick up the electrohub by its side the back is heavy.

Here is a picture of it.
Is that an X quad or a spider X (like this)?

If it's an X, the CG should be right in the middle. If it's a spider, the CG is moved back a few cm. The flight controller should be mounted at the CG, or as close as you can get it. Balance by picking it up on the sides parallel to the middle of the flight controller (or pretty close). If that's what you're doing in the photo, just slide the battery forward a bit until it balances out.
 
#9
I think it is call the deadcat configuration, not sure if that is the spider x. It is not a even X shape.
By moving the battery almost to the front it balanced out but it make the battery connection tight.
 

C0d3M0nk3y

Posted a thousand or more times
#10
I think it is call the deadcat configuration, not sure if that is the spider x. It is not a even X shape.
By moving the battery almost to the front it balanced out but it make the battery connection tight.
Yeah, dead cat and spider are the same. Your CG is probably about halfway between the middle and the back of the ElectroHub plate.
 
#11
I have another question about the electrohub and flying it.

Today I tried to fly the electrohub and I could not keep the throttle at a certain speed to keep the quad level.
I tried to practice keeping it level 3ft off the ground it would drop and touch the ground. Then the propellers would speed up and shoot up in the air after it touched the ground.

not sure if there is something is wrong.

Any thoughts?

Tips keeping it level,..

I manage to break the ties on landing legs,..lol
 

C0d3M0nk3y

Posted a thousand or more times
#13
Today I tried to fly the electrohub and I could not keep the throttle at a certain speed to keep the quad level.
I tried to practice keeping it level 3ft off the ground it would drop and touch the ground.
You might want to practice hovering another foot or two off the ground. If you're too low, you might be in turbulence that your quad is creating. You want to be in "clean air".


Then the propellers would speed up and shoot up in the air after it touched the ground.
This is a quirk that is common on MultiWii multirotors. My quad with a Flip 1.5 does the same thing. There might be a way to fix this with tuning, but I don't know about it if there is.
 

RichB

Senior Member
#17
Draw two imaginary lines between diagonal motors to make an X

The center of the X is the best place to have the CG for even motor loading.

You do not need motor loading to be even to have stable flight, but it's nice for keeping the motors working evenly.

The CG point is the best place to have the flight controller if you are using angle modes. If you are using acro or rate modes, the FC placement does not matter.

With that said, you would need the cg to be *way* off to cause the thing to flip over on takeoff. In fact, I think that's impossible.
 

stay-fun

Helicopter addict
#18
Today I tried to fly the electrohub and I could not keep the throttle at a certain speed to keep the quad level.
Ok, you're not making any sense here. The throttle has nothing to do with keeping a MR level.

I'm familiar with self-level of flight controllers, and "acro mode", in which there is no self-leveling. What is "angle mode"?
 
#20
Here is a video of the issue with the electrohub keeping level. I have to keep making adjustment in the throttle.
even at even throttle is it slowly come down and bounce off the ground. I also have the same issue when trying to land.