
App-8-H6927.tex 20/6/2007 16: 42 Page 434
Appendix 8
Approximate Expressions for the
Dimensionless Aerodynamic Stability
and Control Derivatives
Table A8.1 Longitudinal aerodynamic stability derivatives
Small perturbation derivatives referred to aircraft wind axes
Derivative Description Expression Comments
X
u
Axial force due Drag and thrust
Equation (13.16) to velocity effects due to
velocity perturbation
−2C
D
−V
0
∂C
D
∂V
+
1
1
2
ρV
0
S
∂τ
∂V
X
w
Axial force due Lift and drag effects
Equation (13.27) to “incidence’’ due to incidence
perturbation
C
L
−
∂C
D
∂α
X
q
Axial force due Tailplane drag effect,
Equation (13.46) to pitch rate usually negligible
−
V
T
∂C
D
T
∂α
T
X
˙w
Axial force due