Hell! I moved my control stick left and my model veers off right! And down is up! Here’s a simple solution to the problem.
 
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Servos are crucial electromechanical parts on board many remote control (RC) models. They are generally controlled by means of pulsewidth modulation (PWM): a pulsewidth of 1.5 ms corresponds to the neutral or ‘straight ahead’ position, whilst 1 ms and 2 ms represent the extreme settings of the control. The “polarity” of a servo can simply be reversed, enabling a 1-ms pulsewidth to make the servo disc assume the position previously adopted with a pulsewidth of 2 ms, and vice versa. All we have to do is modify the width of the control pulses.