Longitudinal Stability Research Paper

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Longitudinal stability is the aircrafts ability to return to its original position following a disturbance that causes the aircraft to pitch either nose up or nose down. Longitudinal stability is influenced and dependent on the factors below; Wing location and position to centre of gravity. Horizontal tail surface location to centre of gravity. Tail surfaces size and area. To gain longitudinal stability, the wing and tail moments must be initially balanced. When the aircraft is put in a nose up position the moments will change effecting the elevators (figure 11), so the sums of the forces provide an unbalanced, restoring moment that will bring the nose back down. When thrust is increased, there is a moment produced by the control surfaces which will counteract the tail plane down load to bring the aircraft nose up. The tail plane is located where it is to assist with…show more content…
This air is deflected downwards very slightly, putting the stabiliser in the path of downwash. A downward force needs to act on the horizontal stabilizer (tail plane) in order to balance the aircraft. This downward force will stop the aircraft pitching downward continuously. In steady level flight, there is a downwash of airflow from the wings even though the stabilizer is balanced/level. This airflow or downwash attacks the stabilizer at the top, creating a downward pressure. The faster the aircraft flies, the more downwash and the greater the downward force will become. This acts on the tail plane. However this does not occur on T tail designs. Airflow over the wing is dependent on the speed of the airflow. If airflow is slow over the wing then downwash is reduced. This reduction will cause a weaker downward force to act on the tail plane. So, the nose of the aircraft will pitch down as it will be more "heavy". The angle of attack on the wings reduces along with the

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