Swept Wing

Question 1

What are the characteristics of a high speed aircraft wing?

Answer 1

Thin, minimal camber, swept wing

Question 2

What does a swept wing do to its critical Mach Number and why?

Answer 2

Increases Mcrit Speed
Due to the angle of which the wing is flying through the air. The wing is only reactive to the wind flying at right angle to the leading edge, in reality the air is flying through an angle. The wing is persuaded to believe it is flying slower than it actually is. So airspeed can be increased.

Question 3

What advantages does a jet aircraft gain from a swept wing?

Answer 3

• High Mach cruise speeds (due to the angle of the airflow)
• Stability in turbulence (As swept wings actually have poor lift qualities it means it is less affected by up draughts, leading to a smoother ride)

Question 4

What are disadvantages does a jet aircraft suffer from a swept wing?

Answer 4

Poor lift qualities (it reduces the lift capabilities of the wing)
High Stall Speeds (again due to poor lift capabilities)

Question 5

What are disadvantages does a jet aircraft suffer from a swept wing?

Answer 5

Poor lift qualities (it reduces the lift capabilities of the wing)
High Stall Speeds (again due to poor lift capabilities)
Speed instability (Speed is unstable below Vmd)
A wing-tip stall tendency (There is a high local Cl around the wing tips)

Question 6

Where does a swept wing stall first and why?

Answer 6

Stall at wing tip first
This is because the outer wing section experiences a higher degree of aerodynamic loading. The span wise flow, also as a result of sweep, adds to this affect.
A stall at the wing tip causes the COP to move forward, causing a nose up tendency, causing a worse stall.

Question 7

A wing tip stall is resolved how…

Answer 7

Greater Camber at the tip, this increase air flow thus delaying stall
Washout or twist, creates a lower angle of incidence at the wing tips