Chapter 21 - Stability Flashcards
Increased stability does what to controllability
decreases
What are used to overcome the A/C stability
Control inputs
What is required to stay in equilibrium when out of trim
Control surface input
Static Stability is the
initial motion
Dynamic Stability is the
Subsequence motion
Positively stable =
tendency to return original position
Neutral stable =
No tendency to move
Negatively stable =
Tendency to diverge away
If it take less time to get to half amplitude what is the stability
increased positive dynamic stability
Aerodynamic Centre is
The point at which all AOA stay constant and all pitching moments happen round. (don’t use CofP as it always moving)
Give the AC on the chord for the following
Symmetrical
Cambered
High Speed
25%
23-27%
50%
Rolling Coefficient is
L’ CL’
Yaw Coefficient is
N CN
Pitching Coefficient is
M CM
Longitudinal Static stability is attained with
Tail plane, distance of the tailplane from the CG
A forward CofG does what to stability
More stable
Directional Static stability is attained with
Vertical stabiliser, fwd CofG, Amount of fuselage behind CofG
Lateral Static stability - which is the main contributor
Wing
x 4 Lateral wing stability devices
Dihedral
swept back
High mounted wings
High Keel surface
Absolute angle of attack is
The absolute angle of attack uses zero lift line and RAF
Dorsal + Ventral fins do what to stability, because they are where
Dorsal increases
Ventral decreases
In the keel area above and below the CofG
Stick fixed position means
Pilot or auto pilot is holding control
Stick free means
No force acting on the control column
If a gust of air pitches the nose up in a stick free condition what happens and stability is
The elevator lags behind the stab with pitch up aerodynamic force causes the a/c to pitch up more
unstable
stick free is less stable than stick fixed
yes
