Motor and Prop Rotation for H Frame and X Frame

Hi, and hope all at Emlid and Ardpilot are well.

Am setting up a new quadcopter that is an H-frame style. My previous one was an X frame.

Why does ArduCopter instruct us to configure an H-frame quad with rotation of the motors and props reversed as compared to the setup for an X frame? I am curious to learn what performance and or stability gains are realized by this difference from the X-frame setup.



A H-frame is flexing differently compared to an X-frame. A H-frame introduces thrust vectors through its flexing and with the normal X-frame prop rotation, those thrust vectors will work against the desired yaw direction. This only applies to the H frame configuration that flies with the closed sides at the front and back. Your copter will fly with both prop rotation setups, but yaw will be snappier with the H frame rotation.

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Interesting. Thanks Sebastian, Paul