Question

A civil A/C has maximum lift coefficient of 3. If wing loading is 120 then, find approach speed of the aircraft. Consider sea-level density.

(a) 10.5m/s

(b) 10.50km/s

(c) 12

(d) 120

I have been asked this question in a national level competition.

My question comes from Wing Loading topic in portion Thrust-Weight Ratio and Wing Loading of Aircraft Design

Answer 1

Correct option is (a) 10.5m/s

The best I can explain: Given, civil aircraft, maximum CL = 3, wing loading W/S = 120

Approach speed of civil aircraft is given by,

Va = 1.3*Vstall

Where, Vstall = \(\sqrt{2*(\frac{W}{S})/(ρ*CL)}

= \sqrt{2*(120)/(1.225*3)}\) = 8.08m/s

Now, Va = 1.3*Vstall = 1.3*8.08 = 10.5m/s.