DGCA POF 6. Drag - Pilotexam.in

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Q1. What is the effect on total drag of an aircraft if the airspeed decreases in level flight below that speed for maximum $L/D$?

Drag increases because of increased induced drag.

Drag decreases because of lower induced drag.

Drag increases because of increased parasite drag.

Drag decreases because of lower parasite drag.

Ans: – Drag increases because of increased induced drag.

Q2. By changing the angle of attack of a wing, the pilot can control the aeroplane’s:

lift and airspeed, but not drag.

lift, gross weight, and drag.

lift, airspeed, and drag.

lift and drag, but not airspeed.

Ans: – lift, airspeed, and drag.

Q3. What is the relationship between induced and parasite drag when the gross weight is increased?

Parasite drag increases more than induced drag.

Induced drag increases more than parasite drag.

Both parasite and induced drag are equally increased.

Both parasite and induced drag are equally decreased.

Ans: – Induced drag increases more than parasite drag.

Q4. In theory, if the airspeed of an aeroplane is doubled while in level flight, parasite drag will become:

twice as great.

half as great.

four times greater.

one quarter as much.

Ans: – four times greater.

Q5. As airspeed decreases in level flight below that speed for maximum lift/drag ratio, total drag of an aeroplane:

decreases because of lower parasite drag.

increases because of increased parasite drag.

increases because of increased induced drag.

decreases because of lower induced drag.

Ans: – increases because of increased induced drag.

Q6. (Refer to annex ‘A’) At the airspeed represented by point B, in steady flight, the aeroplane will:

have its maximum $L/D$ ratio.

have its minimum $L/D$ ratio.

be developing its maximum coefficient of lift.

be developing its minimum coefficient of drag.

Ans: – have its maximum $L/D$ ratio.

Q7. Which statement is true relative to changing angle of attack?

A decrease in angle of attack will increase pressure below the wing, and decrease drag.

An increase in angle of attack will decrease pressure below the wing, and increase drag.

An increase in angle of attack will increase drag.

A decrease in angle of attack will decrease pressure below the wing and increase drag.

Ans: – An increase in angle of attack will increase drag.

Q8. On a wing, the force of lift acts perpendicular to, and the force of drag acts parallel to the:

flight path.

longitudinal axis.

chord line.

longitudinal datum.

Ans: – flight path.

Q9. That portion of the aircraft’s total drag created by the production of lift is called:

induced drag, and is greatly affected by changes in airspeed.

induced drag, and is not affected by changes in airspeed.

parasite drag, and is greatly affected by changes in airspeed.

parasite drag, which is inversely proportional to the square of the airspeed.

Ans: – induced drag, and is greatly affected by changes in airspeed.

Q10. The best $L/D$ ratio of an aircraft occurs when parasite drag is:

a minimum.

less than induced drag.

greater than induced drag.

equal to induced drag.

Ans: – equal to induced drag.

Q11. An aircraft has a $L/D$ ratio of 15:1 at 50 kt in calm air. What would the $L/D$ ratio be with a direct headwind of 25 kt?

30:01:00

15:01

25:01:00

7.5:1

Ans: – 15:1

Q12. Which is true regarding aerodynamic drag?

Induced drag is a by-product of lift and is greatly affected by changes in airspeed.

All aerodynamic drag is created entirely by the production of lift.

Induced drag is created entirely by air resistance.

Parasite drag is a by-product of lift.

Ans: – Induced drag is a by-product of lift and is greatly affected by changes in airspeed.

Q13. At a given True Airspeed, what effect will increased air density have on the lift and drag of an aircraft?

Lift will increase but drag will decrease.

Lift and drag will increase.

Lift and drag will decrease.

Lift and drag will remain the same.

Ans: – Lift and drag will increase.

Q14. If the Indicated Airspeed of an aircraft is increased from 50 kt to 100 kt, parasite drag will be:

four times greater.

six times greater.

two times greater.

one quarter as much.

Ans: – four times greater.

Q15. If the Indicated Airspeed of an aircraft is decreased from 100 kt to 50 kt, induced drag will be:

two times greater.

four times greater.

half as much.

one quarter as much.

Ans: – four times greater.

Q16. The best $L/D$ ratio of an aircraft in a given configuration is a value that:

varies with Indicated Airspeed.

varies depending upon the weight being carried.

varies with air density.

remains constant regardless of Indicated Airspeed changes.

Ans: – remains constant regardless of Indicated Airspeed changes.

Q17. The tendency of an aircraft to develop forces which restore it to its original condition, when disturbed from a condition of steady flight, is known as:

manoeuvrability.

controllability.

stability.

instability.

Ans: – stability.

Q18. As Indicated Airspeed increases in level flight, the total drag of an aircraft becomes greater than the total drag produced at the maximum lift/drag speed because of the:

decrease in induced drag only.

increase in induced drag.

increase in parasite drag.

decrease in parasite drag only.

Ans: – increase in parasite drag.

Q19. The resistance, or skin friction, due to the viscosity of the air as it passes along the surface of a wing is a type of:

induced drag.

form drag.

parasite drag.

interference drag.

Ans: – parasite drag.

Q20. Which relationship is correct when comparing drag and airspeed?

Parasite drag varies inversely as the square of the airspeed.

Induced drag increases as the square of the airspeed.

Parasite drag increases as the square of the lift coefficient divided by the aspect ratio.

Induced drag varies inversely as the square of the airspeed.

Ans: – Induced drag varies inversely as the square of the airspeed.

Q21. If the same angle of attack is maintained in ground effect as when out of ground effect, lift will:

decrease, and parasite drag will decrease.

increase, and induced drag will decrease.

decrease, and parasite drag will increase.

increase and induced drag will increase.

Ans: – increase, and induced drag will decrease.

Q22. Which statement is true regarding aeroplane flight at L/Dmax?

Any angle of attack other than that for L/Dmax increases parasite drag.

Any angle of attack other than that for L/Dmax increases the lift/drag ratio.

Any angle of attack other than that for L/Dmax increases total drag for a given aeroplane's lift.

Any angle of attack other than that for L/Dmax increases the lift and reduces the drag.

Ans: – Any angle of attack other than that for L/Dmax increases total drag for a given aeroplane’s lift.

Q23. Aspect ratio of a wing is defined as the ratio of the:

square of the chord to the wingspan.

wingspan to the wing root.

area squared to the chord.

wingspan to the mean chord.

Ans: – wingspan to the mean chord.

Q24. A wing with a very high aspect ratio (in comparison with a low aspect ratio wing) will have:

increased drag at high angles of attack.

poor control qualities at low airspeeds.

a lower stall speed.

reduced bending moment on its attachment points.

Ans: – a lower stall speed.

Q25. At a constant velocity in airflow, a high aspect ratio wing will have (in comparison with a low aspect ratio wing):

increased drag, especially at a low angle of attack.

decreased drag, especially at a high angle of attack.

increased drag, especially at a high angle of attack.

decreased drag, especially at low angles of attack.

Ans: – decreased drag, especially at a high angle of attack.

Q26. (Refer to annex ‘B’) Which aircraft has the highest aspect ratio?

Ans: – 2.

Q27. (Refer to annex ‘B’) Which aircraft has the lowest aspect ratio?

Ans: – 1.

Q28. (Refer to annex ‘B’) Consider only aspect ratio (other factors remain constant). Which aircraft will generate greatest lift?

Ans: – 2.

Q29. (Refer to annex ‘B’) Consider only aspect ratio (other factors remain constant). Which aircraft will generate greatest drag?

Ans: – 1.

Q30. What happens to total drag when accelerating from $C_{LMAX}$ to maximum speed?

Increases.

Increases then decreases.

Decreases.

Decreases then increases.

Ans: – Decreases then increases.

Q31. (Refer to annex ‘C’), the whole aircraft $C_{L}$ against $C_{D}$ polar. Point ‘B’ represents:1. Best Lift/Drag ratio.2. The critical angle of attack.3. Recommended approach speed.4. Never exceed speed $(V_{NE})$.

1 and 2.

1 only.

2 and 3.

4 only.

Ans: – 1 only.

Q32. If the Indicated Airspeed of an aircraft in level flight is increased from 100 kt to 200 kt, by what factor will (i) TAS (ii) $C_{D}$ (iii) $D_{i}$ change?

(i) 2(ii) $1/4$(iii) $1/16$

(i) 0(ii) 4(iii) 16

(i) 4(ii) $1/16$(iii) $1/4$

(i) 2(ii) $1/16$(iii) $1/4$

Ans: –

(i) 2
(ii) $1/16$
(iii) $1/4$

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