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Here are a few things you can try that may lead to a solution:
Check if the odometry is calculated properly. For example, by plotting out /ardrone/odometry/pose/pose/position/x:y:z with rqt_plot
Check the frame of reference the odometry topic is published in, and the fixed frame in rviz. If the fixed frame is coincident with the drone's centre, then you'll get what you're seeing in rviz currently.