Question

As a designer let’s consider that we want to build an aircraft weighing 28000 units at take-off. How many engine will require if our thrust loading T.L. is 0.71 and thrust per engine is 10000 unit?

(a) 2

(b) 3

(c) 4

(d) 1

The question was posed to me in unit test.

I want to ask this question from Fixed-Engine Sizing in portion Initial Sizing of Aircraft Design

Answer 1

Right choice is (a) 2

For explanation I would say: Given, thrust per engine T = 10000 unit and thrust loading T.L. = 0.71

Now, take-off gross weight is 28000 units.

Now, number engines required is given by,

N = W*T.L. / T = 28000*0.71/10000 = 1.98.

We cannot use 1.98 engines so we will take the nearest integer. Hence, the answer will be 2.