4 Unsteady aerodynamics

Question 1

For unsteady aerodynamics, what is the new Lift equation for step change in incidence, for an aerofoil?

Answer 1

w is the gust velocity, and the other term is the Wagner function.

Question 2

What is this?

Answer 2

The Wagner function; means that the force acts like a real force (not instantaneous).
(For step incidence questions)

Question 3

What is this?

Answer 3

Dimensionless time, the speed divided by the number of chords.
(For unsteady aerodynamics)

Question 4

What is ‘w’ for unsteady aerodynamics?

Answer 4

Question 5

What is this?

Answer 5

Downwash velocity

Question 6

What is the incremental incedence?

Answer 6

Question 7

What is the equation for incremental incidence?

Answer 7

Question 8

In unsteady aerodynamics, what is the new lift equation for sharp edge gust, for an aerofoil?

Answer 8

The new term here is the Kussner function, which explains how aero forces build up upon entering gust

Question 9

For harmonic gust what is the equation for gust?

Answer 9

Question 10

What is the lift equation for a harmonic gust, for an aerofoil?

Answer 10

(a1 is the slope of CL for an aerofoil, would be different for a wing)

Question 11

What is the Sear’s function?

Answer 11

Question 12

Point, to get the Lift equation for a wing the incremental incidence needs to be accounted for in the CL part of the equation.

Answer 12