Stalling Flashcards
What happens if energy of the air flow gets too low?
Knocked off the surface by the adverse pressure gradient, this is called separation and creates the stall.
What happens as AOA increases?
Adverse pressure gradient gets stronger which leads to separation. Separation point moves forward.
What is effective AOA?
Angle between EAF and chord line.
What us EAF?
Effective Airflow.
The airflow that is going over the wing.
How does aspect ratio effect critical AOA?
Higher aspect ratio = smaller critical angle
What is a deep stall?
Loss of elevator authority.
Wake of wing impinges on tail surface rendering it useless
How can you reduce stalling tendencies and vortices?
Wing fence.
Vortilon.
Winglet.
Tip tank.
Vortex generator.
Notched leading edge.
How does a wing fence reduce tip stalling?
Stop the spanwise flow.
Reduces trailing edge vortices
What does a vortilon do?
Improves low speed performance, therefore increasing resistance to spin and stall.
What characteristics do aerofoils prone to sudden stall have?
Sharp leading edge.
Low thickness chord ratio.
Max thickness and camber more aft.
What characteristics do aerofoils prone to progressive stall have?
Rounded leading edge.
High thickness/chord ratio.
Max camber and thickness more fwd.
How do trailing edge flaps affect the Cl, AOA graph?
Increased Cl at the same AOA.
Reduce critical AOA.
How do leading edge flaps effect the Cl max, AOA graph?
Increases critical AOA.
Slightly increases Cl max.
How do leading edge slats effecf Cl, AOA graph?
Only increase critical AOA.
What could happen high angle of attack during turn?
The wing moving down can stall due to reduced lift.
