P Post-test 4 (Aerodynamics)

1. Assume that, at a point on the wing of the Concorde supersonic transport, the air temperature is -4°C and the pressure is 1063 N/m². Calculate the density (kg/m³) at this point.

A. 0.002751477

B. 0.02063608

C. 0.013757387

D. 0.017196733

C. 0.013757387

2. How can the pilot increase the rate of turn and decrease the radius at the same time?

A. Steepen the bank and increase airspeed.

B. Steepen the bank and decrease airspeed.

C. All of the above

D. Shallow the bank and increase airspeed.

B. Steepen the bank and decrease airspeed.

3. A wing of constant thickness which is not swept back:

A. Will stall evenly across the span.

B. Will pitch nose down approaching the stall due to the forward movement of the centre of pressure.

C. Will stall at the tip first due to the increase in spanwise flow.

D. Could drop a wing at the stall due to the lack of any particular stall-inducing characteristics.

D. Could drop a wing at the stall due to the lack of any particular stall-inducing characteristics.

4. If the aeroplane's undercarriage is lowered in flight, the (i) _____ drag will (ii) _____ and the nose-down pitching moment will (iii) _____.

A. (i) Induced; (ii) increase; (iii) increase

B. (i) Induced; (ii) decrease; (iii) increase

C. (i) Form; (ii) increase; (iii) increase

D. (i) Form; (ii) increase; (iii) be unchanged

C. (i) Form; (ii) increase; (iii) increase

5. What true airspeed and angle of attack should be used to generate the same amount of lift as altitude is increased?

A. A higher true airspeed for any given angle of attack.

B. A constant angle of attack and true airspeed.

C. A lower true airspeed and higher angle of attack.

D. The same true airspeed and angle of attack.

A. A higher true airspeed for any given angle of attack.

6. Sensitivity for a spiral dive will occur when:

A. The static directional stability is negative and the static lateral stability is positive.

B. The static directional stability is positive and the static lateral stability is relatively weak.

C. The Dutch-roll tendency is too strongly suppressed by the yaw damper.

D. The static lateral and directional stability are both negative.

B. The static directional stability is positive and the static lateral stability is relatively weak.

7. On a highly tapered wing without wing twist, the stall will commence:

A. Simultaneously across the whole span.

B. At the centre of the span.

C. At the root.

D. At the tip.

D. At the tip

8. As a general rule, if the aerodynamic angle of attack of an aerofoil is slightly increased, the centre of pressure will:

A. Move forward towards the leading edge.

B. Move towards the tip.

C. All of the above

D. Never move.

A. Move forward towards the leading edge.

9. If a landing is to be made without flaps, the landing speed must be:

A. The same as for a landing with flaps but with a steeper approach.

B. Reduced.

C. Increased.

D. The same as for a landing with flaps.

C. Increased.

10. A wing fence:

A. All of the above

B. Acts as a lift-dumping device.

C. Increases lateral control.

D. Reduces spanwise flow on a swept wing, thus reducing induced drag.

D. Reduces spanwise flow on a swept wing, thus reducing induced drag.

11. When a blade moves about the flapping hinge:

A. The drag forces on the blade change.

B. The drag forces on the blade change and the angle of attack (AOA) changes.

C. The pitch angle of the blade always reduces.

D. None of the above

B. The drag forces on the blade change and the angle of attack (AOA) changes.

12. Why is the effect of nose-wheel steering not accounted for in VMCG?

A. Because VMCG must apply to wet and/or slippery runways.

B. Because it has no effect on the value of VMCG.

C. Because the nose-wheel steering may be inoperative after an engine failure.

D. Because it must be possible to abandon a take-off after the nose wheel leaves the ground.

A. Because VMCG must apply to wet and/or slippery runways.

13. At the same Mach number, the normal shockwave compared with the oblique shockwave has:

A. Greater expansion

B. Smaller compression

C. Greater compression

D. Smaller expansion

C. Greater compression

14. As the angle of attack increases, the stagnation point:

A. Moves towards the upper surface.

B. Moves towards the lower surface.

C. Does not move.

D. None of the above

B. Moves towards the lower surface.

15. Positive static stability of an aeroplane means that once it has been displaced, the:

A. Initial tendency to move is away from its position of equilibrium.

B. Tendency will be to move with an oscillating motion of decreasing amplitude.

C. Tendency will be to move with an oscillating motion of increasing amplitude.

D. Initial tendency to move is towards its position of equilibrium.

D. Initial tendency to move is towards its position of equilibrium.

16. The altimeter on a low-speed Cessna 150 reads 5685 ft. The outside air temperature is 500°R, and a pitot tube mounted on the wingtip measures a pressure of 1820 psf. What is the true velocity of the airplane?

A. 321.5855398

B. 482.3783097

C. 401.9819248

D. 64.31710796

A. 321.5855398

17. What is the purpose of the lead-lag (drag) hinge in a three-bladed, fully articulated helicopter rotor system?

A. Provide geometric balance.

B. Offset lateral instability during autorotation.

C. Compensate for the Coriolis effect.

D. None of the above

C. Compensate for the Coriolis effect.

18. The lowest value of critical Mach number (Mcrit) results from _____ camber and a _____ cross-section.

A. Small; thin

B. Large; thick

C. Small; thick

D. Large; thin

B. Large; thick

19. On a hot day, the measured temperature and pressure are 35°C and 20 inHg, respectively. Calculate the density ratio.

A. 0.781256842

B. 0.93750821

C. 0.125001095

D. 0.625005473

D. 0.625005473

20. In a glide descent at the optimum speed, the effect that increasing the nose-down pitch angle has on the glide distance is that:

A. It increases, but only in a headwind.

B. It has no effect.

C. It decreases.

D. It increases.

C. It decreases.

21. The positive limiting load factor for large jet transport aeroplanes at VB is:

A. 2.5

B. 1.75

C. 1

D. 1.5

A. 2.5

22. The atmospheric zone where the temperature remains fairly constant is called the:

A. None of the above

B. Stratosphere

C. Troposphere

D. Ionosphere

B. Stratosphere

23. If a force of 20 newtons moves a mass 5 metres:

(1) The work done is 100 Nm.

(2) The work done is 100 joules.

(3) The work done is 4 joules.

(4) The work done is 0.25 joules.

The correct statements are:

A. 1 and 3

B. 1 only

C. 2 only

D. 1 and 2

D. 1 and 2

24. What is a purpose of flight spoilers?

A. Reduce lift without increasing airspeed.

B. None of the above

C. Increase the camber of the wing.

D. Direct airflow over the top of the wing at high angles of attack.

A. Reduce lift without increasing airspeed.

25. Calculate the pressure at an altitude of 5 km in the standard atmosphere in pascals.

A. 67493.14011

B. 10798.90242

C. 53994.51209

D. 80991.76814

C. 53994.51209

26. Mach number is defined as:

A. IAS divided by the local speed of sound.

B. TAS divided by the local speed of sound.

C. All of the above

D. Speed of sound at sea level divided by the local speed of sound.

B. TAS divided by the local speed of sound.

27. The point on an aerofoil section through which lift acts is the:

A. Centre of gravity.

B. Aerodynamic centre.

C. Midpoint of the chord.

D. Centre of pressure.

D. Centre of pressure.

28. Indications of an icing-induced stall can be:

(1) An artificial stall warning device

(2) Airspeed close to the normal stall speed

(3) Violent roll oscillations

(4) Airframe buffet

(5) Violent wing drop

(6) Extremely high rate of descent while in a "normal" flight attitude

A. 1, 4 and 6

B. 1, 2, 4 and 5

C. 1, 3 and 5

D. 3, 4, 5 and 6

D. 3, 4, 5 and 6

29. A servo tab is operated:

A. Directly by the pilot to produce forces which in turn move the main control surfaces.

B. None of the above

C. Automatically, and moves in the same direction as the main control surfaces.

D. By a trim wheel and moves in the opposite direction to the main control surfaces when moved.

A. Directly by the pilot to produce forces which in turn move the main control surfaces.

30. For any given configuration, the stick shaker is activated when the IAS is:

A. 1.3 Vs

B. Greater than Vs

C. 1.2 Vs

D. 1.12 Vs

B. Greater than Vs

31. The most important aspect of the "backside" of the power curve is that:

A. The elevator must be pulled to lower the nose.

B. Altitude cannot be maintained.

C. Speed is unstable.

D. The aeroplane will not stall.

C. Speed is unstable.

32. The speed to obtain the minimum glide angle occurs at:

A. Cl/Cdmax

B. Clmax

C. Cl/Cd2max

D. Cl3/Cd2max

A. Cl/Cdmax

33. On a hot day, the measured temperature and pressure are 35°C and 20 inHg, respectively. Calculate the density ratio.

A. 0.781256842

B. 0.93750821

C. 0.625005473

D. 0.125001095

C. 0.625005473

34. "S" and "q" in the lift equation represent:

A. Wing span and dynamic pressure

B. Static pressure and the chord

C. Wing area and static pressure

D. Wing area and dynamic pressure

D. Wing area and dynamic pressure

35. The increase of drag above the critical Mach number is due to:

A. Increased skin friction

B. Wave drag

C. Increased angle of attack

D. Increased interference drag

B. Wave drag

36. Calculate the density at an altitude of 5 km in the standard atmosphere in slug/ft³.

A. 0.000285537

B. 0.002141531

C. 0.001427687

D. 0.001784609

C. 0.001427687

37. Which of the following increases the stalling angle?

A. Slats

B. Ailerons

C. Spoilers

D. Flaps

A. Slats

38. What do ruddervators do?

A. None of the above

B. Control pitch and roll.

C. Control yaw and roll.

D. Control pitch and yaw.

D. Control pitch and yaw.

39. Sensitivity to Dutch roll is increased by:

A. Increased anhedral

B. Increased static lateral stability

C. A forward movement of the CG

D. Increased static directional stability

B. Increased static lateral stability

40. The angle of attack of an aerofoil is the angle between the:

A. Longitudinal axis and the undisturbed airflow

B. Chord line and the undisturbed airflow

C. Longitudinal axis and the horizontal

D. Longitudinal axis and the chord line

B. Chord line and the undisturbed airflow

41. Consider the low-speed flight of the space shuttle as it is nearing a landing. If the air pressure and temperature at the nose of the shuttle are 2.08 atm and 290 K, respectively, what is the specific volume in m³/kg?

A. 0.079004346

B. 0.493777164

C. 0.592532597

D. 0.395021731

D. 0.395021731

42. Which of the following statements is correct with regard to the phugoid of a conventional aeroplane?

A. Damping of the phugoid is usually very weak.

B. The speed is constant throughout one period of the phugoid.

C. The usual period-time of a phugoid is 3 seconds.

D. An aft CG position decreases the period time of the phugoid.

A. Damping of the phugoid is usually very weak.

43. Air is flowing horizontally at a speed of 100 mph through a duct with a cross-sectional area of 4 sq ft. The duct gradually narrows down to a throat section. If a U-tube shows a pressure difference between the throat and main sections of 7 inches of water, what is the cross-sectional area of the throat? Assume that air is incompressible and has a density of 0.002378 slug/ft³.

A. 4.626 sq ft

B. 3.855 sq ft

C. 2.57 sq ft

D. 2.056 sq ft

C. 2.57 sq ft

44. A pipe is gradually tapering in size, diminishing by 0.1 sq ft per foot run. What is the change in velocity per foot run where the pipe is 4 sq ft in cross-section, if the velocity there is 90 ft/s?

A. 2.25 fps per foot

B. 3.25 fps per foot

C. -2.25 fps per foot

D. -3.25 fps per foot

A. 2.25 fps per foot

45. An airplane is flying at sea level at an airspeed of 160 knots. What is the difference between total and static pressure?

A. 0.4824 psi

B. 1.0854 psi

C. 0.603 psi

D. 0.9045 psi

C. 0.603 psi

46. An airplane weighing 5,000 lb requires 100 hp to move the wing at a certain angle of attack. If 500 lb is added to the weight of the airplane, what horsepower is required for the wing if flown at the same angle of attack as before?

A. 92.32 hp

B. 173.1 hp

C. 207.72 hp

D. 115.4 hp

D. 115.4 hp

47. An airplane is flying at 10,000 ft altitude. The difference between impact and static pressure is 0.25 lb/in². What is the airspeed in knots?

A. 216 knots

B. 120 knots

C. 96 knots

D. 180 knots

B. 120 knots

48. On a hot day, the measured temperature and pressure are 16°C and 20 inHg, respectively. Calculate the density in kg/m³.

A. 0.163188248

B. 1.019926551

C. 0.815941241

D. 1.223911861

C. 0.815941241

49. The altimeter on a low-speed Cessna 150 reads 5685 ft. The outside air temperature is 500°R, and a pitot tube mounted on the wingtip measures a pressure of 1820 psf. What is the true velocity of the airplane?

A. 321.5855398

B. 482.3783097

C. 64.31710796

D. 401.9819248

A. 321.5855398

50. All other factors remaining constant, the stalling speed increases when:

A. Altitude is increased

B. The mass decreases

C. Spoilers are retracted

D. Pulling out of a dive

D. Pulling out of a dive