Chapter 24 - Directional + Lateral Stability Flashcards
what is sideslip angle
longitudinal axis and the RAF
What alternative name for directional stability
weathercock
If the aircraft has had a gust causing it to yaw left heat is the the term for Nose to the RAF Slide slip angle Positive or negative sideslip If positively stable which Cn response
Nose to the left of the airflow
right side slip angle
positive side slip
positive Cn response
What is the greatest restoring force for directional stability
fin
x4 factors increasing the restoring moment
CG FWD
larger fin
higher IAS
Larger sideslip angle
straight fin is what aspect ratio
efficient or not
stalling AOA higher or lower
high aspect ratio
efficient
lower AOA
Swept fin is what aspect ratio
efficient or not
stalling AOA higher or lower
low aspect ratio
not as efficient
higher stalling AOA
Do wings and fuselage help with directional stability
Wings yes because more effective wing showing
fuselage depends of CofG position, if FWD more so
A ventral fin will do what to keel effect and lateral stability
increase keel effect
decrease lateral stability
If an A/C recovers quickly from a wing drop it is said to have?
Strong lateral stability
If a gust gives a positive side slip angle (right wing down) if positively stable which CL’ is required
negative
What gives you a large AOA on the lower wing to restore equilibrium
Dihedral wings
How does swept back give greater lateral stability
the down going wing will have more surface area into the effective airflow
High wing gives what effect and how
Keel effect
the upwash on the low wing moves over the top causing the CofP to move O/B and correct
High keel surface is
The amount of airframe above and below the CofG
