Question

Determine the value of rudder deflection δr for an aircraft which is flying in north with the velocity of 60.5 m/s under the crosswind of 5m/s from east to west with Cnβ=0.02/deg and Cnδr = -0.045/deg, where sideslip angle β is -4.72°.

(a) -2.09°

(b) 3.5°

(c) -4.5°

(d) -4.74°

The question was posed to me during an interview.

This interesting question is from Lateral-Directional Static Stability and Control in division Stability, Control, and Handling Qualities of Aircraft Design

Answer 1

Correct choice is (a) -2.09°

The explanation is: Given, North velocity n = 60.5m/s, East to west velocity e = 5m/s.

Now, rudder deflection δr = – [Cnβ/ Cnδr]*β = -[0.02/-0.045]*(-4.72) = -2.09°.