Aerodynamics/Stability question

[fredgrav]

Hi guys, finally found an answer !

The neutral-point (NP) is the point around which all the aerodynamic forces are balanced. The stick free neutral point for an aeroplane is the aerodynamic center that the aeroplane would have with no pilot control force if the elevator and its mechanical linkage to the cockpit control had no mass and no friction.

hn = h0 + hs * Vs ( as/aw) [1 - (de / da )]

hn = neutral-point
h0 = aerodynamic center of the wing [typically 0.25]
hs = stabilizer efficiency [typically 0.6] - [0.9 for a T-tail]
Vs = stabilizer volume coefficient
as = lift curve slope of the stabilizer
aw = lift curve slope of the wing
de /da = change in stabilizer downwash angle versus change in wing angle-of-attack (AOA) [typically 0.5 to 0.33]

Beyond NP, there are two types of maneuvering points, the stick-fixed maneuver point and the stick-free maneuver point:
- The stick-fixed maneuver point is defined as the center of gravity position for which no change in the elevator angle (stick travel) is required for a normal acceleration (ng);
- The stick free maneuver point is defined as the center of gravity position for which no change in the hinge moment or stick force is required to maintain a normal acceleration (ng).

Everyone who wants to shed some light on this topic is widely appreciated ...

A pleasant evening,
fredgrav