NOTE:  Do not confuse this XYZ with the Cartesian coordinate system.

IMU Orientation

The small white arrow refers to the direction the IMU is facing.  Select the appropriate direction.

Find the center of gravity (CG) of the helicopter when fully loaded. 

If the helicopter is used to carry payload then that payload must be mounted onto the helicopter.

Horizontal CG must line up with the main shaft of the helicopter.  Distribute helicopter components and/or payload to meet this criteria.

A simple test for horizontal CG is to rotate the main rotors perpendicular to the length of the helicopter.  Support the helicopter from underneath the blade grips and observe if the helicopter tips over forward or backward.  Adjust as necessary.

To find the vertical CG, first remove the main blades, hang the helicopter by the tail and drop a plumb line along the side of the helicopter. 

The CG is where the plumb line intersects the main shaft of the helicopter.

NOTE:  Before attempting to hang your helicopter from the tailboom it is best to support moveable components and other components that may experience stress from the extreme angle.

NOTE:  When measuring the distance of the IMU and GPS for the CG measure from the center of each module.

To use the above setup as an example:

The IMU is facing backwards.

The IMU is 12 cm forward of the main shaft and 8 cm below the CG.

GPS is 63 cm behind the main shaft and 4 cm above the CG.

Exact measurements are not required.  For example if the GPS is 63.4cm behind the main shaft then 63cm will do.  Round it off to the nearest ones or units.

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