# Aircraft Design Questions and Answers – Flight Mechanics – Gliding Flight-2

«
»

This set of Aircraft Design Assessment Questions and Answers focuses on “Flight Mechanics – Gliding Flight-2”.

1. Graphical representation of sink rate of sailplane is called ____________
a) typical speed polar
b) drag polar wing
c) lift curve of wing
d) propulsion systems

Explanation: The graphical representation of sink rate for sailplane is called speed polar. Speed polar is also known as hodograph. Drag polar is graphical representation of drag characteristics. Lift curve is used to provide relationship between lift and angle of attack.

2. Velocity for the best glide ratio is 100ft/s. Determine velocity for minimum sink rate.
a) 76ft/s
b) 124m/s
c) 23fts
d) 45 fts2

Explanation: Minimum sink rate velocity = 0.76*best glide ratio velocity = 0.76*100 = 76ft/s.

3. Variometer is used for _____________
a) informing pilot when glider is in lift
b) increase lift
c) thrust reversal
d) increase thrust produced

Explanation: Variometer is used to provide information to the pilot about glider. It is used to provide data about when glide is in lift. Thrust reversal are used to increase drag during landing and to reduce landing distance.

4. Consider turning glide operation with bank angle of 1.5 and Weight of 125 unit. Find lift.
a) 125.042
b) 56
c) 120
d) 345

Explanation: Lift= Weight/cosine (bank angle) = 125/cosine 1.5 = 125.042 unit.

5. Determine the value of turn rate. Consider glider has centripetal acceleration of 10 and velocity of 9.5.
a) 1.052
b) 9.5
c) 10
d) 2.8

Explanation: Turn rate = centripetal acceleration/velocity = 10/9.5 = 1.052 unit.

6. Determine the value of best glide ratio velocity. Consider velocity for minimum sink rate is 10 fps.
a) 13.15 fps
b) 20 fps
c) 11 fps
d) 34 fps

Explanation: Given, velocity for minimum sink rate v = 10 fps
Velocity for best glide ratio = v/0.76 = 10/0.76 = 13.15 fps.

7. Consider turning gliding flight. Turn rate is given as 0.2 unit and velocity of flight is 10 unit. Find the value of turn radius.
a) 50
b) 100
c) 2
d) 8

Explanation: Turn radius = velocity/turn rate = 10/0.2 = 50 unit.

8. Find the range of glider which has L/D of 13.6 and is descending from 5km.
a) 68km
b) 12 m
c) 12 inch
d) 68 m

Explanation: Range = altitude*L/D = 5*13.6 = 68km.

9. If KCD0 is 0.014 then, find lift to drag ratio for minimum sink.
a) 3.66
b) 36.6
c) 1.4
d) 24

Explanation: Lift to drag ratio of minimum sink (0.1875/KCD0)0.5
= (0.1875/0.014)0.5
= 3.66.

10. Consider a glider is descending from 2km altitude. If it covers range of 30km then, at which aerodynamic efficiency the glider was flying?
a) 15
b) 60
c) 12
d) 21 