Introduction to Airplane Performance Assignment Week 3

1. Suppose an aircraft is flying in such atmosphere that there is no wind. As altitude increases, how Mach number changes for same speed. Ans : a

a. Increases. b. Decreases. c. Remains unchanged. d. Insufficient data.

2. For same speed as altitude increases how Reynolds number and viscosity of flow changes respectively. Ans : d

a. Increases, increases. b. Decreases, decreases. c. Decreases, increases. d. Increases, decreases.

3. Under same atmospheric conditions when landing gears are taken in from out position. Among 0 which will change significantly ? Ans : b

a. . b. 0 . c. Both equal. d. Cant say.

4. A low speed aircraft while tested under same aerodynamic conditions in a wind tunnel, what we duplicate for dynamic similarity point of view. Ans : a, d

a. Reynolds number. b. Mach number. c. Angle of attack. d. Ratio of inertia to viscous force.

5. In 2D aerofoil increases with angle of attack. This increment is due to increment in : ans : c

a. Only induced drag. b. Only skin friction. c. Only flow separation. d. Induced drag and skin friction.

6. In following figure for a given altitude power available and power required Vs velocity plot is given. At which velocity the rate of climb will be maximum? Ans : c

a. A b. B c. C d. D

7. Which of the following parameters can be read from the parabolic polar diagram of an airplane? Ans : d

a. The aspect ratio of the wing and the induced drag coefficient. b. The minimum rate of descent and the induced drag. c. The induced drag and the parasite drag. d. The minimum glide angle and the parasite drag coefficient.

Data for question 8 to 12 Drag polar of an aircraft is given by = .020 + .019 2 and = 4.5 per radian.

B A C D

8. What is the value of parasite drag coefficient? Ans : a a. 0.020 b. 0.019 c. 1.052 d. 1.025

9.

is maximum for = Ans : c

a. 1.052 b. 1.777 c. 1.025 d. Insufficient data

10. 3/2

is maximum for = Ans : b

a. 1.052 b. 1.777 c. 3.157 d. Insufficient data

11. For thrust required minimum theoretically at what angle of attack the aircraft is flying? Is this

angle of attack advisable? Ans : b

a. 13 degree, yes b. 13 degree, no c. 22.6 degree, yes d. 22.6 degree, no

12. For power required minimum theoretically at what angle of attack the aircraft is flying? Is this

angle of attack advisable? Ans : d

a. 13 degree, yes b. 13 degree, no c. 22.6 degree, yes d. 22.6 degree, no