Propeller planes add a lot of torque when powered ie for take off, you have to counter it with about 5 degrees of opposite rudder, a really twitchy pig of a thing with a hand controller to get right! Or you’re using a Thrustmaster T16000 twist grip for your rudder, there is a youtube fix for their notoriously bad/jittery rudder potentiometers - basically you have to remove a few mm off the tabs that hold the pot in place because they transfer the weight of your hand to the pot when used and it messes it up. Otherwise maybe try reducing the sensitivity of your rudder around the centred position in the axis settings of the game. If its on pedals …still reduce the sensitivity around the center position.