Stalling Flashcards
Does the wing stall at the stalling (critical) angle of attack?
NO
It is the angle at which the wing produces maximum lift before stalling
How does aspect ratio affect the effective angle of attack
Low aspect ratio = High effective AOA
high aspect ratio = low effective AOA
On a rectangular wing, what part stalls first and why
The root
Because there is a greater downwash at the tip causing a smaller effective angle of attack
Less downwash at the root causing s greater effective angle of attack
Why is it more favourable to have a stall start at the wing root
Turbulent air hits the tailplane causing natural buffer = stall warning
Ailerons remain in un-stalled flow for longer = some lateral control
Wing drop is less pronounced
How does effective angle affect the aircraft stalling angle
Greater effective angle
Less the stalling angle
How does downwash affect the stalling angle
Bigger the downwash the bigger the stall angle of attack
What part of an elliptical wing stalls first
The training edge
Why does an elliptical wing have undesirable stall characteristics
Stall is sudden
Little / no buffer on tailplane
Ailerons ineffective
Large roll rates if wing drops
Where does a moderately tapered wing stall first
The middle
What are the stall characteristics of a moderately tapered wing
No stall warning (buffer)
Ailerons quickly become ineffective
Where does a highly tapered - swept wing stall first
Wingtip
Highly tapered / swept wing stall characteristics
Wing tip stalls first
Can have big roll rate (if one wing stalls first)
Ailerons don’t work well
No buffet (warning)
Centre of pressure moves forwards = pitch up
Increased downwash at wing root increases tailplane downforce = increasing AOA
What type of aircraft if most likely to be involved in a deep stall
Low tapered wing, sweepback and high elevator
What causes a deep stall
The cp moving forward on the wing causing the aircraft to pitch back, this puts the elevator into the turbulent wake of the stalled wing losing its effectiveness
What does a wing fence do
reduced spanwise flow on a sweptwing aircraft by creating a physical boundary to help try and prevent the wing tip stalling first
What does a vortilon do
Attached to leading edge
During High angles of attack it protrudes into upper wing spanwise flow
Causes tight High energy turbulent “barrier” to try prevent spanwise flow
To try and stop wing tip stalling first
How does washout and reduced camber stop wingtip stall
Washout out means the tip is at a lower angle of attack than the wing root
Meaning that it won’t reach its critical angle as soon
What thickness-chord ratio has the highest stalling AOA
A high thickness to chord ratio
(Big leading edge radius) increases the AOA
What can be added to the wing root to try and make the wing root stall first
A stall strip on the leading edge
Makes a sharper leading edge
What thickness - chord ratio has the most progressive stall
High thickness - chord ratio
What thickness - chord ratio has the least progressive stall
Low thickness- chord ratio
What is wing loading
The aircrafts weight divided by the wing area
What affect does wing loading have on stalling angle of attack
Harder you make the wing work the lower the stalling angle of attack
What affect does trailing edge flaps have on the stalling angle
Reduce the stalling angle
