Question

An aircraft is designed to be in steady level flight with weight of 1500N and CL of 1.0. Determine at which speed we need to design this aircraft so that it can achieve this requirement. Consider density as 1.2 kg/m^3 and reference area as 2m^2.

(a) 35.35m/s

(b) 56m/min

(c) 56m/s

(d) 70km/s

This question was addressed to me during an interview for a job.

This question is from Flight Mechanics in division Performance and Flight Mechanics of Aircraft Design

Answer 1

Right option is (a) 35.35m/s

Easy explanation: Given, steady level flight. Weight W=1500N, CL=1.0, density = 1.2kg/m^3, reference area S=2m^2.

Now, velocity is given by,

V = \(\sqrt{\frac{2*W}{density*S*CL}}\)

= \(\sqrt{\frac{2*1500}{1.2*1.0*2}}\)  = 35.35m/s.