Centre of Gravity/Pressure
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Centre of Gravity and Pressure Interaction
An aircraft will spin about its vertical axis, running through the centre of gravity, such that the centre of pressure trails its direction of flight. For any body to achieve stable flight, you want the front to be heavy and the back to be big. This is why darts and arrows are configured as they are.
Diagram A
One might think this arrangement is the "most stable", but in fact its hyper stability causes the airplane to "over correct" when disturbed from straight flight. It lacks aerodynamic "dampening".
Diagram B
This is perhaps the most unstable arrangement. With the centre of pressure forward of the centre of gravity, the aircraft's natural tendency would be to fly "tail first". The pilot would have a very difficult time correcting the flight path. The ailerons and especially the rudder would be hyper sensitive.
Diagram C
This is the ideal arrangement. The centre of pressure is aft of the centre of gravity, causing the aircraft to fly straight forward. If disturbed, the centre of pressure corrects the flight path with ever decreasing oscilations until equilibrium is achieved again.
Diagram D
This arrangement results in "neutral stability" - neither stable nor unstable. If the flight path were disturbed, the aircraft would not naturally correct itself.