Module 1 Longitudinal Stability Flashcards
What does the magnitude of the pitching moment dependent on?
The distance from the COG.
What would a to far aft COG cause?
Difficulty for the tail plane to produce sufficient restoring moment.
How do secondary forces effect pitching moment about the Centre of gravity?
Generated on the main plane pitching moments about the CG, since these forces are most significant on the a/c the magnitude and location change with aoa and airspeed.
What other effects can a tail plane provide?
Produces a moment which can neutralize any excessive pitching moment.
What are the wings effects on longitudinal stability?
Level flight CP is usually behind CG. If there is a nose up disturbance, aoa increases and wings will produce more lift. Additional lift will be produce and a restoring moment nose down which means it will be a stable effect.
What is Centre gravity effect on longitudinal stability?
FWD CG is a stable feature as it provides long leverage to the tail plane. Where as a rearward CG is unstable it results in short leverage to the tail plane.
What is a fuselage effects on longitudinal stability?
Can be looked as a force couple the total force of the object is 0 but the moment is not, so due to aoa can produce a positive moment when aoa is positive
What is longitudinal dihedral effect on longitudinal stability?
Incident angle of the main plane could be different to the incident angle of the tail pane, longitudinal dihedral is the difference in angle of the two. Longitudinal dihedral makes the airflow around the a/c form a effective aoa to the wing, which is smaller than the actual setting of aoa so it will decrease the magnitude of disturbance.
Sweep back wings on longitudinal stability?
CP is more rearward for sweepback wings than that of straight wings so it ensures CP is behind CG, which will ensure a restoring moment.
