Questions and Answers - Aerodynamics | Aircraft Systems

Questions and Answers - Aerodynamics

Study Aid Questions

Fill in the Blanks

1. The study of objects in motion through the air and the ________ governing that motion come from the Greek combination of “aero” and “________”.

2. Atmospheric pressure is measured in ________ with a ________.

3. As an aircraft descends atmospheric pressure _______, the amount of oxygen in the air ________, and temperature ________.

4. Density varies ________ with temperature and ________ with pressure.

5. A body at rest does not move unless a force is applied to it is Newton’s law ________ and is known as the law of ________.

6. According to Bernoulli’s principle, fluid flowing through a constriction experiences a(n) ________ in speed.

7. Velocity increases and pressure decreases on the ________  of the wing.

8. A pilot can increase the lift of an aircraft by increasing the ________.

9. The acute angle the wing chord makes with the ________ axis is called angle of incidence.

10. The boundary layer is the layer of ________ closest to the surface and its behavior is controlled in order to minimize ________ drag and skin friction drag.

11. Fluids always move from ________ to ________ pressure. This principle explains the spanwise movement of air flow from the bottom of the wing ________ and upward around the wing creating spillage over the wingtip called ________.

12. An object that tends to returns to equilibrium is said to have positive ________ stability.

13. ________ control the lateral movements of the aircraft, the ________ controls the longitudinal movements, and the ________ controls the directional movements.

14. An autogryo is an aircraft with a horizontal rotor that is ________ and turns due to the passage of air ________ through the rotor.

15. The blade with the decreased angle of attack tends to flap ________.

16. The collective pitch control is operated with the ________ hand and is used to make pitch angle changes to ________ the main rotor blades.

17. There is a ________ of lift between the advancing and retreating blade.

18. Autorotation is possible through a freewheeling unit, a special ________ mechanism, which automatically disengages the engine in the event of its failure.

19. Helicopters with tandem rotors use the pedals to tilt the main rotors. When the ________ pedal is pushed forward the aft rotor moves to the ________.

20. Swaging tools generally have a ________ dimensions in an attempt to avoid defective or inferior swages.

21. Cables that travel completely through bulkheads require the use of a ________ and should not be deflected more than ________ from a straight line.

22. A groove or knurl around the end of the barrel of a ________ can be used to identify the ________ threads.

23. Structural alignment is the ________ of the main structural component related to the longitudinal datum line parallel to the aircraft centerline and the lateral datum line parallel to the line joining the ________.

24. Hard landings and abnormal flight experiences prompt a check of the wing ________ and angle of ________.

25. The most common method of safety wiring is the ________ however; a ________ method can be used for smaller screws and tight spaces.


1. Air is considered a fluid. TRUE/FALSE

2. Atmospheric pressure changes with altitude. TRUE/FALSE

3. Aircraft can fly faster at lower altitudes because there is more pulling force from the engine cutting through the air. TRUE/FALSE

4. Density varies directly with humidity. TRUE/FALSE

5. Airflow over an airfoil can be explained using Bernoulli’s principle and this pressure differential is called lift. TRUE/FALSE

6. One wing can have numerous airfoil sections each with unique properties. TRUE/FALSE

7. The efficiency of a wing is measured in terms of wing camber and AOA. TRUE/FALSE

8. An aircraft has four forces acting upon it at all times: gravity, lift, thrust and weight. TRUE/FALSE

9. Induced drag increases as AOA increase. TRUE/FALSE

10. Center of pressure has the greatest affect on the stability of an aircraft. TRUE/FALSE

11. The vertical stabilizer is the primary surface that controls directional stability on the horizontal axis. TRUE/FALSE

12. Trim tabs enable the pilot to correct any unbalanced condition that may exist during flight without touching the flight controls. TRUE/FALSE

13. Canards are often used in swept wing aircraft to prevent spanwise air movements at high angles of attack. TRUE/FALSE

14. Stick shakers were installed in hydromechanical flight control systems which provide an artificial stall warning. TRUE/FALSE

15. At high forward speed a situation called retreating blade stall can occur because of the high AOA and slow relative wind speed.TRUE/FALSE

16. Control surfaces must be rebalanced whenever there is weight added to a control surface.TRUE/FALSE

17. The balance beam rebalancing method requires a specialized manufacturer made tool. TRUE/FALSE

18. Lead and steel are the most common materials used to balance control surfaces. TRUE/FALSE

19. The Type certification Data Sheet is issued by the manufacturer and includes information such as airspeed limitations, weight limits, and fuel type. TRUE/FALSE

20. A 7x19 cable is very rigid and used for engine controls and trim tab controls. TRUE/FALSE

21. Soldering cable ends is a common technique used to prevent fraying. TRUE/FALSE

22. Cables are checked for corrosion by bending them.TRUE/FALSE

23. A double‐wrap safety wire method is preferred when securing a turnbuckle. TRUE/FALSE

24. Rudder alignment is done by removing the controls surface from its hinges and passing a plumb bob though the hinge attachment holes. TRUE/FALSE

25. Cotter pins, unlike safety wire, can be re‐used. TRUE/FALSE

Knowledge Application Questions

1. Why is air considered a fluid?

2. What is atmospheric pressure and how is it measured?

3. What is the relationship between density, pressure, and temperature?

4. What is the difference between absolute humidity and relative humidity?

5. What is Newton’s third law and what does it state?

6. Describe how Bernoulli’s principle relates to a wing.

7. Describe what happens to the resultant force as the AOA increases.

8. Describe the other force produced besides lift as the relative motion of the air moves over the wing. 

9. What does control and controllability mean for a pilot and the aircraft?

10. Explain the aerodynamic effect that occurs at and above the speed of sound.

11. Explain what fully articulated means in relation to a helicopter rotor system.

12. How does Newton’s third law relate to helicopters?

13. Explain what a correlator is and what it does.

14. What are the most common causes of high frequency vibrations?

15. Why is no clutch necessary on a helicopter engine with a free turbine?

16. Describe the use of pulleys and pulley guards.

17. Control cable rigging generally consists of what three steps?

18. What is the purpose of a turnbuckle?

19. Where are cable drums typically found and what do they do?

20. What are the types of inspection programs helicopter operates use in accordance with 14 CFR part 91?

Multiple Choice Questions

1. What happens to the pressure of a fluid in a container when it is heated?
a. Pressure increases
b. Pressure decreases
c. Pressure remains the same

2. At sea level, what is the average atmospheric pressure in psi, “Hg, and millibars respectively?
a. 1.47 psi, 29.92”Hg, 1013.25 mb
b. 14.7 psi, 29.92”Hg, 10.13 mb
c. 14.7 psi, 29.92”Hg, 1013.25 mb

3. A wing with a high fineness ratio has which of the following characteristics?
a. Thin wing, small amount of skin friction
b. Thick wing, small amount of skin friction
c. Thin wing, large amount of skin friction

4. When the AOA increases to maximum lift, what has been reached?
a. Critical angle
b. Burble point
c. Both A & B

5. Force acts in what direction, in relation to the relative wind?
a. Parallel
b. Perpendicular
c. At a 45° angle

6. Exposed aircraft components create resistance known as
a. Parasite drag
b. Skin friction drag
c. Induced drag

7. is the quality of the response of an aircraft to the pilot's commands during maneuvers.
a. Stability
b. Controllability
c. Maneuverability

8. Which axis extends from nose to tail?
a. Vertical axis
b. Lateral axis
c. Longitudinal axis

9. What type of stability can be artificially increased with a yaw dampener?
a. Directional
b. Dynamic
c. Dutch roll

10. Which of the following type of aircraft structures reduce fuel consumption and increases range?
a. Wing fences
b. Winglets
c. Both A & B

11. Compressible aerodynamics deals with speeds at
a. Mach I and above
b. 250 mph and below
c. Mach 3‐Mach 5

12. Supersonic flight refers to flight between
a. 0‐Mach 1
b. Mach 1‐Mach 3
c. Mach 5 and above

13. What type of rotor is found on aircraft with dual rotor blades?
a. Fully articulated
b. Semi rigid
c. Rigid

14. Drift in the direction of the tail rotor during hover is called
a. Ground effect
b. Translational tendency
c. Translational lift

15. Effective translational lift is experienced at what airspeed?
a. Between hover and 16 knots
b. Between 16‐24 knots
c. 24 knots and above

16. A helicopter with counterclockwise rotating main rotor would experience which of the following conditions if dissymmetry of lift were allowed to exist with no corrective action?
a. Roll to the left
b. Roll to the right
c. Drift to the left

17. How does a pilot compensate for blowback?
a. Move the cyclic forward
b. Move the cyclic aft
c. Pull up on the collective

18. What component transmits the control inputs from the collective and cyclic to the main rotor blades?
a. Transmission
b. Control rod
c. Swash plate

19. Where is the throttle control located in a helicopter?
a. On the collective
b. On the cyclic
c. On a lever next to the collective

20. What is the primary purpose of the helicopter main rotor transmission?
a. Increase engine output RPM to optimum rotor RPM
b. Decrease engine output RPM to optimum rotor RPM
c. Synchronize the rotation of the engine with the rotor

21. During static balancing, an upward movement of the trailing edge of a control surface on a balance stand indicates:
a. An overbalance designated with a (+) sign
b. An underbalance designated with a (‐) sign
c. An overbalance designated with a (‐) sign

22. Which rebalancing method can be performed without removing the control surface from the aircraft?
a. Calculation method
b. Scale method
c. Balance beam method

23. Where should rigging and alignment checks be performed?
a. On the ramp
b. In an enclosed hangar
c. At a specialized maintenance facility

24. may be used to force the primary nut thread against the bolt or screw thread
 a. Lock nut
b. Lock washer
c. Pal nut

25. ELT tests should be conducted
a. During the last 5 minutes of any hour
b. During the first 5 minutes of any hour
c. During the first 15 minutes of any hour