How does CG affect longitudinal stability?
As long as the CG is maintained within the allowable limits for its weight, the airplane will have adequate longitudinal stability and control. If the CG is too far aft, it will be too near the center of lift and the airplane will be unstable, and difficult to recover from a stall.
What are the conditions for longitudinal static stability?
The center of gravity must lie ahead of the neutral point for positive stability (positive static margin). If the center of gravity is behind the neutral point, the aircraft is longitudinally unstable (the static margin is negative), and active inputs to the control surfaces are required to maintain stable flight.
Which CG is more stable?
To keep it simple, loading the aircraft with a forward CG within limits will increase the aircrafts stability as opposed to loading an aircraft with a more aft (rearward) CG within limits of course will decrease stability.
Why do aircraft have an all moving tail?
It may also be useful to use an all-moving tail on low-speed aircraft since it is possible to devise an arrangement which gives great flexibility in choosing a stick-free neutral point position. On physical grounds, it may be shown that a simple surface attached to the fuselage by a pivot and directly geared to the stick, is unsatisfactory.
Where are the aerodynamic centres of the wing and tailplane?
The wing and tailplane aerodynamic forces and moments are assumed to act at their respective aerodynamic centres, which, to a good approximation, lie at the quarter-chord points of the mac of the wing and tailplane, respectively.
Why does an aeroplane need static and dynamic stability?
There is some range required for the CoG. An aeroplane must have static and dynamic stability in order to be easy to control: with a gust hitting the aeroplane, a statically stable aeroplane returns to a stable attitude without the pilot having to apply a correction. Like a car driving straight when not holding the steering wheel.
What happens if the tailplane of an elevator is moved?
If the tailplane is moved via an irreversible power-control system, stick-free stability is no longer of significance, and suitable stick-forces can be arranged by artificial means. The object of such an arrangement is to avoid the difficulties associated with large changes of elevator effectiveness at high Mach numbers.