16. Basic aerodynamic theory (Lift / Drag Ratio)

Question 1

If you require 1,200 units of lift to support the aeroplane and the drag is 100 units, then the L/D ratio is (10:1 / 12:1 / 120:1 / 5:1)

Answer 1

12:1

Question 2

At high angles of attack, total drag is high due to …….. … …. . For 1,200 units of lift, the cost might be 240 units if drag. The L/D ratio is ……..

Answer 2

Induced drag; 5:1

Question 3

At low angles o attack and high speeds, the total drag is high due to …….. drag. If the required 1,200 units of lift are generated at a cost of 200 units, the L/D ratio is ……..

Answer 3

Parasite; 6:1

Question 4

If at say 4 degrees angle of attack where the total drag is a minimum for the particular aerofoil we are considering, the 1,200 units of lift are obtained for a cost of only 80 units drag, then the L/D ratio is ……..

Answer 4

15:1

Question 5

The angle of attack that gives the best L/D ratio is the (most / least) efficient angle of attack

Answer 5

Most

Question 6

If you fly at the airspeed at the best L/D ratio, then the required list is obtained for the (minimum / maximum) drag

Answer 6

Minimum

Question 7

Time achieve the maximum gliding range, you should fly the aeroplane at the speed for:

a) maximum L/D ratio
b) minimum L/D ratio
c) maximum lift

Answer 7

A

Question 8

The most efficient angle of attack is usually about…….. degrees

Answer 8

4