# Aircraft Performance Questions and Answers – Effect on the Take-off Distances of Flight Variables

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This set of Aircraft Performance Questions and Answers for Campus interviews focuses on “Effect on the Take-off Distances of Flight Variables”.

1. There are two atmospheric effects on the take-off distances.
a) True
b) False

Explanation: There are two atmospheric effects on the take-off distances. They are:

• The take-off with reference to the indicated airspeed
• The output of the power plant which is roughly proportional to relative density.

2. Which of the following is the correct formula of ground run distance with respect to aircraft weight?
a) SG=$$\frac{WV_{LOF}^2}{2g[F_N+D+\mu (W-L)]_{0.7V_{LOF}^2}}$$
b) SG=$$\frac{WV_{LOF}^2}{2g[F_N-D+\mu (W-L)]_{0.7V_{LOF}^2}}$$
c) SG=$$\frac{WV_{LOF}^2}{2g[F_N+D-\mu (W-L)]_{0.7V_{LOF}^2}}$$
d) SG=$$\frac{WV_{LOF}^2}{2g[F_N-D-\mu (W-L)]_{0.7V_{LOF}^2}}$$

Explanation: The formula for the ground run distance with respect to aircraft weight is given by SG=$$\frac{WV_{LOF}^2}{2g[F_N-D-\mu (W-L)]_{0.7V_{LOF}^2}}$$ where W is weight, V is velocity, L is lift, D is drag, g is acceleration due to gravity and μ is runway coefficient of rolling friction.

3. Which of the following is the correct formula of airborne distance with respect to aircraft weight?
a) SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2+V_{LOF}^2}{2g}+35\Big\}$$
b) SA=$$\frac{W}{(F_N+D)_{av}}\Big\{\frac{V_{2}^2+V_{LOF}^2}{2g}+35\Big\}$$
c) SA=$$\frac{W}{(F_N+D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$
d) SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$

Explanation: The airborne distance is given by SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$ where

• W is weight
• D is drag
• G is acceleration due to gravity
• V is velocity
• FN is normal force.
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4. Which of the following statement is not correct?
a) The airborne distance is given by SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$
b) The ground run distance is given by SG=$$\frac{WV_{LOF}^2}{2g[F_N-D-\mu (W-L)]_{0.7V_{LOF}^2}}$$
c) The ground run distance is directly proportional to aircraft weight
d) The ground run distance is directly proportional to aircraft drag

Explanation: The correct statements are as follows:

• The airborne distance is given by SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$
• The ground run distance is given by SG=$$\frac{WV_{LOF}^2}{2g[F_N-D-\mu (W-L)]_{0.7V_{LOF}^2}}$$
• The ground run distance is directly proportional to aircraft weight.

5. The increase in aircraft weight by 10% will result in increase in aircraft ground run distance by 20%.
a) True
b) False

Explanation: The increase in aircraft weight by 10% will result in increase in aircraft ground run distance by 20%. The ground run distance is given by SG=$$\frac{WV_{LOF}^2}{2g[F_N-D-\mu (W-L)]_{0.7V_{LOF}^2}}$$. From the formula it is known that the ground run distance is directly proportional to aircraft weight.

6. What is the use of the headwind?
a) To change the datum height
b) To change the datum temperature
c) To change the fuel ratio
d) To change the pressure ratio

Explanation: The headwind is used to change the datum speed of the take-off. This headwind effects the ground run speed. For every 10% change in headwind, there is 20% decrease in the ground run distance.

7. The headwind only effects in the kinematic energy in the case of the airborne distance.
a) True
b) False

Explanation: The headwind only effects in the kinematic energy in the case of the airborne distance. The headwind is used to change the datum speed of the take-off. This headwind effects the ground run speed. For every 10% change in headwind, there is 20% decrease in the ground run distance.

8. There is no effect of runway conditions on the airborne distance.
a) True
b) False

Explanation: There is no effect of runway conditions on the airborne distance. The runway condition includes:

• Slope of the runway
• Friction of the runway.

9. Which of the following will not effect the ground run distance?
a) TAS
b) EAS
c) Weight
d) Thrust

Explanation: The ground run distance is not effected by thrust. The factors that affect ground run distance are:

• TAS
• EAS
• Density.

10. The ground run distance is effected by the inverse of the density and directly proportional to square of the true airspeed.
a) True
b) False

Explanation: The ground run distance is effected by the inverse of the density and directly proportional to square of the true airspeed. The ground run distance is not effected by thrust. The ground run distance is not effected by thrust. The factors that affect ground run distance are: TAS, EAS and density.

11. The effect of TAS on airborne distance is half that of the ideal case.
a) True
b) False

Explanation: The effect of TAS on airborne distance is half that of the ideal case. The airborne distance is given by SA=$$\frac{W}{(F_N-D)_{av}}\Big\{\frac{V_{2}^2-V_{LOF}^2}{2g}+35\Big\}$$ where W is weight

• D is drag
• G is acceleration due to gravity
• V is velocity
• FN is normal force.

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