An A/C is cruising with thrust to weight of 0.9. If A/C is powered by prop engine then, find maximum lift to drag?

1.11

2.11

3.12

4.221

Correct Answer : 1.11

Explanation : Given, thrust loading at cruise T.L. = 0.9, prop aircraft.
For prop aircraft maximum L/D = Cruise L/D
Hence, T.L. = D/L.
Hence, cruise L/D = 1/(T/W) = 1/0.9 = 1.11.

Recently Updated in Aircraft Design Questions

What should be the aspect ratio (AR) of the prop aircraft if it is designed to work with maximum loiter wing loading of 32, CD0 = 0.06, dynamic pressure of 20 unit and Oswald efficiency as 0.6.

9.65

8.54

7.65

7.54

Correct Answer : Option (B) : 7.54

Explaination :

An aircraft is to be designed to have max lift coefficient as 2.8 and at q=10Pa. If maximum load factor n=5 then, what will be the stall speed?

1.80m/s

1.80mph

2.80mph

2.80m/s

Correct Answer : Option (A) : 1.80m/s

Explanation :

An aircraft has lift to drag ratio during cruise as 2.5 and load factor as 1.2. Which value of thrust loading should be selected?

0.28

0.38

0.48

0.58

Correct Answer : Option (C) : 0.48

Explanation : Given, load factor n=1.2, lift to drag L/D = 2.5
Now, n at cruise is given by, n = (T/W)*(L/D).
Hence, T/w is given as,
T/W = n / (L/D) = 1.2/2.5 = 0.48.