Question

Determine the value of form factor for fuselage if fuselage fineness ratio f is 1.2.

(a) 35.725

(b) 12

(c) 100

(d) 423.2

The question was asked during an interview.

My question is taken from Aerodynamics topic in chapter Aerodynamics of Aircraft Design

Answer 1

Right option is (a) 35.725

To explain I would say: Form factor = 1 + (60/f^3) + (f/400)

= 1 + (60/1.2^3) + (1.2/400)

= 1+34.722+0.003 = 35.725.