07-11-2012, 02:43 PM
Aerodynamics II
aerodynamics2.ppt (Size: 795.5 KB / Downloads: 152)
Stability
Static stability – initial tendency
Positive– initially returns to position before displacement
Neutral– tendency to remain in displaced position
Negative (bad thing) – tends to continue away from displaced position in same direction
Stability – how do we get it?
“When the airplane is banked without turning, it tends to sideslip or slide downward toward the lowered wing. Since the wings have dihedral, the air strikes the low wing at much greater angle of attack than the high wing.”
The stall
Stalls occur by exceeding the critical angle of attack
Stalls can occur at any attitude and any airspeed
“Stall speed” of an aircraft refers to straight-and-level, unaccelerated flight
The spin
The spin is the result of stalling in “uncoordinated” flight. (more later)
Both wings are stalled…one wing is “more stalled” than the other:
Maneuvering Speed (VA)
Fastest speed an aircraft can travel when a full deflection of the controls is possible.
Increases with increased weight (why?)
Gyroscopic precession
“90 degrees ahead in the direction of rotation”
Occurs during pitching (e.g. rotation about the lateral axis)
Right-yaw tendency when the nose is rising
Left-yaw tendency when the nose is falling