Aero CBT Questions

=ROTARY AERO CBT QUESTIONS=

=Atmosphere= 1. Atmosphere’s greatest air density is____.
 * Greatest at the Earth’s surface and decrease as distance from the surface increases

2. What is parasite power?
 * Is power required to overcome friction drag of all aircraft components, except rotor blades.

3. The density altitude rule of thumb is___.
 * DA=PA + Temp Correction+ Humidity correction.

4. The Standard Rate of Change for air temperature is?
 * 15°C at sea level and cooling 2°C/1000 ft

5. What is basic assumption for standard adiabatic lapse rate?
 * Air temperature decreases as altitude increases.

6. What measurements are assumed for standard atmosphere?
 * 15°C, 29.92 in HG 14.7 psi at sea level

7. What causes Earth’s atmosphere pressure at altitude?
 * Downward pressure exerted from of air above that altitude

8. What is standard atmosphere?
 * The temperature and pressure of standard day

9. What does rotor profile power assume?
 * A constant minimum pitch angle and a constant coefficient of drag value

10. What is profile drag?
 * Friction drag of rotor blades

11. What is atmosphere?
 * Mass of air that completely envelopes the Earth

12. What is power required?
 * Amount of engine power necessary to maintain a constant rotor speed

13. The Earth’s atmosphere what non-varying constituents and in what proportions?
 * 78% Nitrogen and 21% Oxygen by volume

14. What are the most common varying constituents of the atmosphere?
 * Carbon Dioxide, Hydrogen, and Neon

15. What is induced power?
 * Is the power required to overcome induced drag

=Flight Phenomena= 1. What can cause a later one-per-rev vibration?
 * Spanwise and chordwise imbalance

2. What should the pilot do when the main rotor returns to a positive thrust condition?
 * Adjust controls to regain balanced flight

3. What procedures are used to prevent dynamic rollover?
 * A smooth moderate collective reduction of approximately 40% or less (at a rate less than full up to full down in 2 sec)

4. What factors may cause or aggravate power required exceeding power available?
 * High G loading, rapid maneuvering, spool up time, loss of wind effect, change of wind

5. Which one of the following is an indication associated with retreating blade stall?
 * Abnormal vibrations

6. What should a pilot do if power required exceeds power available?
 * Maintain Nr, place the RPM switch to FULL INCR, increase/decrease airspeed to 50 knots, level the wings and jettison fuel as required.

7. What can aggravate a power exceeding power available condition?
 * Extreme and rapid flight control inputs airspeed

8. What are some indications of compressibility effect?
 * A cyclic feedback

9. What can cause high frequency vibrations?
 * An engine, driveshaft, coupling, dry bearing, or out-of-track tail rotor

10. Why is mast bumping so dangerous?
 * Mast bumping may lead to mast deformation and structural failure

11. What techniques should be used in the event of ground resonance?
 * Use the rotor brake, if installed

12. What happens to the retreating blade angle-of-attack as airspeed increases?
 * It increases to maintain equal lift until it reaches its max pitch or the blade stalls

13. What will happen when the main rotor is unloaded and thrust is significantly reduced?
 * The aircraft rolls right, because of the thrust of the tail rotor, which produces a rolling moment above the longitudinal axis of the helicopter

14. How can a helicopter prevent dynamic rollover?
 * By keeping the aircraft properly trimmed and flying the aircraft smoothly off or onto the ground

15. When will compressibility effects occur?
 * When the tip section of the advancing blade approaches supersonic

16. What is the recovery procedure for uncommanded right roll for flight below 1 G?
 * Immediately apply aft cyclic to establish positive G load on the rotor, then center laterally.

17. What are the vortex ring state recovery procedures?
 * Adding forward cyclic to gain airspeed while decreasing collective

18. What are the key means of differentiating compressibility effects from retreating blade stall?
 * Compressibility effects occur at high RPM, while retreating blade stall occurs at low RPM

19. When is vortex ring state most common?
 * When the helicopter is in a high power setting and a high rate of descent as in a vertical landing

20. What is ground resonance?
 * When the rotor systems becomes unbalanced from excessive lead/lag causing displacement of the CG from the center

21. What are some of the less significant causes of mast bumping?
 * Maximum sideward/rearward flight, slideslip, and blade stall conditions

22. What vibration patterns are associated with retreating blade stall?
 * In single-rotor helicopters, a 2 per-rev vibration

23. In the negative stall area the rotational velocity of the retreating blade is?
 * Faster than aircraft airspeed an air flows from the leading to trailing edge of the blade

=ROTOR BLADE AERODYNAMICS=

1. What is induced flow?
 * The flow of air in a downward direction as a result of the rotor blades in rotation.

2. What are symmetrical airfoils?
 * Those which have identical size and shape on the upper and lower surfaces.

3. Why is the aerodynamic center of an airfoil used along with lift and drag coefficients to analyze airfoil performance?
 * Because the sum of the moments produced about the aerodynamic center remains constant for any pre-stall angle of attack.

4. What is flapping?
 * Vertical blade movement.

5. How are the aerodynamic forces working on a helicopter different from those that work on a fixed wing aircraft?
 * Helos fly as a result of the aerodynamic forces produced when air passes about the rotor blades.

6. What is the definition of thrust in the blade element theory?
 * The force that is produced by the rotor system and drives the helicopter through the air.

7. What is the rotor disk?
 * Area of the circle bounded by the tip-path plane.

8. Geometric imbalance occurs?
 * When rotor blade centers of mass are not equidistant from the center of rotation.

9. What is the relationship between pitch angle and angle of attack?
 * As blade pitch increases, the angle of attack increases.

10. What is the angle of attack of an airfoil?
 * Angle formed between the relative wind and the chord-line.

11. What is the pitch angle of an airfoil?
 * The angle formed between the chord line and the plane of rotation.

12. What is the camber line of a rotor blade?
 * Line which lies halfway between the upper and lower surfaces of the blade.

13. What is the chord of the airfoil?
 * Distance from tip of leading edge to the trailing edge of an airfoil.

14. What is the tip-path plane?
 * The plane of rotation in which the rotor blade tips travel.

15. What is the relationship between rotational flow and tip-path plane?
 * Rotational flow is parallel to the tip-path plane and at a constant rpm in a no-wind hover.

16. What is the camber line of a rotor blade?
 * Line which lies halfway between the upper and lower surfaces of the blade.

17. What causes lead and lag?
 * When a blade’s center of mass is closer to the center of rotation it will tend to lead (move faster).

18. What is relative wind?
 * Wind in motion with respect to an airfoil.

19. What is the camber of an airfoil?
 * Difference between the camber line and the chord line.

20. What is the chord line of an airfoil?
 * A straight line connecting the leading edge of the airfoil to the tip of the trailing edge.

21. When does the momentum theory of helicopter aerodynamics work well for a helicopter?
 * In a steady state, no wind hover.

22. Which system uses an underslinging mounting design?
 * Semi-rigid rotor system.

23. What is the only true statement about geometric twist?
 * Blade designs generally use 6 to 12 degrees of geometric twist.

24. What is the aerodynamic center of an airfoil?
 * The point along the blade where all changes in lift effectively take place.

25. What is rotational flow?
 * Horizontal flow of air opposite the direction of blade travel.

=ROTOR BLADE AERODYNAMICS=

26. What is induced flow?
 * The flow of air in a downward direction as a result of the rotor blades in rotation.

27. What are symmetrical airfoils?
 * Those which have identical size and shape on the upper and lower surfaces.

28. Why is the aerodynamic center of an airfoil used along with lift and drag coefficients to analyze airfoil performance?
 * Because the sum of the moments produced about the aerodynamic center remains constant for any pre-stall angle of attack.

29. What is flapping?
 * Vertical blade movement.

30. How are the aerodynamic forces working on a helicopter different from those that work on a fixed wing aircraft?
 * Helos fly as a result of the aerodynamic forces produced when air passes about the rotor blades.

31. What is the definition of thrust in the blade element theory?
 * The force that is produced by the rotor system and drives the helicopter through the air.

32. What is the rotor disk?
 * Area of the circle bounded by the tip-path plane.

33. Geometric imbalance occurs?
 * When rotor blade centers of mass are not equidistant from the center of rotation.

34. What is the relationship between pitch angle and angle of attack?
 * As blade pitch increases, the angle of attack increases.

35. What is the angle of attack of an airfoil?
 * Angle formed between the relative wind and the chord-line.

36. What is the pitch angle of an airfoil?
 * The angle formed between the chord line and the plane of rotation.

37. What is the camber line of a rotor blade?
 * Line which lies halfway between the upper and lower surfaces of the blade.

38. What is the chord of the airfoil?
 * Distance from tip of leading edge to the trailing edge of an airfoil.

39. What is the tip-path plane?
 * The plane of rotation in which the rotor blade tips travel.

40. What is the relationship between rotational flow and tip-path plane?
 * Rotational flow is parallel to the tip-path plane and at a constant rpm in a no-wind hover.

41. What is the camber line of a rotor blade?
 * Line which lies halfway between the upper and lower surfaces of the blade.

42. What causes lead and lag?
 * When a blade’s center of mass is closer to the center of rotation it will tend to lead (move faster).

43. What is relative wind?
 * Wind in motion with respect to an airfoil.

44. What is the camber of an airfoil?
 * Difference between the camber line and the chord line.

45. What is the chord line of an airfoil?
 * A straight line connecting the leading edge of the airfoil to the tip of the trailing edge.

46. When does the momentum theory of helicopter aerodynamics work well for a helicopter?
 * In a steady state, no wind hover.

47. Which system uses an underslinging mounting design?
 * Semi-rigid rotor system.

48. What is the only true statement about geometric twist?
 * Blade designs generally use 6 to 12 degrees of geometric twist.

49. What is the aerodynamic center of an airfoil?
 * The point along the blade where all changes in lift effectively take place.

50. What is rotational flow?
 * Horizontal flow of air opposite the direction of blade travel.

=Questions from ICW software, possibly test questions for NEW AERO COURSE=

HELO POWERED FLIGHT ANALYSIS
• What is the goal of achieving max glide range?
 * Covering the greatest distance possible

• Which of the following variables determines Vne for TH-57?
 * D.A., gross weight, instrument flight rules and the automatic flight control system

• What happens to the tail rotor requirements at higher speeds?
 * Tail rotor requirements are significantly reduced by the vertical stabilizer

• What is the goal of achieving max endurance?
 * Making the available fuel last as long as possible.

• What effect does power required by tail rotor have on power available to main rotor system?
 * A reduction in the power required by the tail rotor results in more power available to the main rotor system.

• Which of the following atmospheric conditions will cause engine power available to decrease?
 * Increasing altitude or increasing temperature

• Which effort is excess engine power concentrated towards and why?
 * A climbing conditions since this produces a significant increase in parasite drag and the tail rotor power requirements.

• How can that tail rotor drift be countered?
 * Displacing cyclic left will tilt the main rotor system left so as to overcome right drift caused by the tail rotor drift.

• Why does the vertical stabilizer affect the tail rotor loading?
 * It is shaped like an airfoil and produces lift in the opposite direction of torque effect.

• An increase in mass air flow in forward flight will result in _____
 * the requirement for decreased climb power

• While helo encounters ground effect_____
 * Less power is required because there is less induced drag to overcome.

• Why do different pitch angles on the tail rotor blades require different power settings?
 * Tail rotor is subject to the same drag forces as the main rotor and power is required to overcome these forces.

• When does parasite power become important?
 * As airspeed increases

• As airspeed increases, what causes the aircraft to steer (weather-vane) into relative wind?
 * Parasite drag on the longitudinal surface of aircraft

• How will tailwind affect max range airspeed?
 * Optimum airspeed will decrease but range increases significantly

• What effect will increased power required at tail rotor have on main rotor?
 * Power available to main rotor will decrease

• What is power required?
 * Total of induced, profile and parasite powers

• Max glide range is based on which of the following?
 * Highest lift-to-drag ratio

• What is relationship between fuel flow and engine power?
 * Proportional

• Why is a cambered horizontal stabilizer incorporated in a helo?
 * To provide a downward lifting force on tail of aircraft

• At what rated will max airspeed for level flight decrease when above 3,000 ft. density altitude and gross weight above 3,000 lbs?
 * 7.0 KIAS, 1,000 ft.

• As tail rotor pitch angle is increased, power required will_____
 * Increase as a result in decrease power available to main rotor.

• What are the characteristics of a tail rotor system on a single rotor helo?
 * Requires little power, produces good yaw control and works just like the main rotor system.

AUTOROTATIONS
• If resultant aerodynamic force vector of a blade element diagram is aft of vertical axis, the force in considered to _____
 * Anti-autorotative

• What is optimum rotor RPM to be maintained during autorotation?
 * 94-95%

• When conducting an autorotation to water landing, every effort should be made to do which of the following prior to touchdown?
 * Alert crew and secure all loose objects.

• Operating range for TH-57 rotor system during autorotation is _____
 * 90-107%

• Flight condition in low altitude, high airspeed area of the Ht/Vel diagram reduces the chances for successful transition to autorotation. What determines successful transition?
 * Pilot reaction time

• What area of Ht/Vel diagram should be avoided?
 * Low altitude, high airspeed.

• Anti-autorotative force _____ when pilot _____ collective.
 * Increases…..raises

• The deceleration (flare) at end of autorotation decreases as airspeed and rate of descent and increases _____
 * Rotor RPM

• When conducting an autorotation to trees, execute flare to arrive at top of trees with _____
 * Zero ground speed and zero rate of descent.

• The airspeed for min. rate of descent during an autorotation is _____
 * 50 KIAS

• What force allows pilot to increase rotor RPM during unpowerd flight?
 * Pro-autorotative force

• Yaw experience during entry into autorotation is result of _____
 * Loss of torque

• Flying in red area of Ht/Vel diagram _____
 * Is not recommended in event of engine failure

• DRIVEN region of rotor disk, during unpowerd flight is considered _____
 * Anti-autorotative

• Max airspeed for TH-57 during autorotation _____
 * 100 KIAS

• DRIVING region of rotor disk, during unpowerd flight is considered _____
 * Pro-autorotative

• To transition to autorotation, collective is lowered to reduce pitch angle and in-plane drag. Select remaining steps that are required to complete transition.
 * Reverse induced flow and stabilize rotor RPM.

• What two factors have the greatest affect on autorotative descent?
 * Airspeed and rotor RPM

• In unpowerd flight the _____ is reversed.
 * Induced flow

• To achieve the max glide distance, the best horizontal speed is _____
 * 72 KIAS

• Rotor RPM will stabilize when pro-autorotative force equals _____
 * In-plane drag

• During autorotation, what form of energy drives the rotor system?
 * Induced flow

=Possible Questions/Answers for New Test=

not detailed but def accurate! OhhRah FUNBUS East Coast!


 * Reaction to Dynamic Rollover ~ lower collective


 * Entry to AutoRotation does not need what? ~ left pedal


 * Definition of Autorotation


 * High Vibration is caused by ~ barbell shaft


 * Frequency on the ground is called ~ Ground Resonance


 * Increase in density altitude ~ decreases power available


 * Settling caused by ~ excesive cyclic


 * In a flare why does RPM increase ~ look it up!!! but def a question


 * Symmetry of lift has ~ no effect on CG


 * Anti Rotation ~ may decelerate Nr


 * Describe Undersling ~ Aligns CG from Flapping Hinge


 * Getting out of Vortex Ring State ~ increase forward speed and move collective down


 * What vectors make up Relative Wind ~ Induced Velocity and Linear Velocity


 * How do you counter act torque ~ anti torque peddals


 * rotor tip vortices in forward flight are ~ similar to a planes


 * 100 % humidity will have how much water vapor ~ 4%


 * CH46 tandem rotor design counteracts torque ~ even number of rotors in opposite direction


 * What effects does a descent speed on autorotation ~ Nr


 * Indications of Retreating Blade Stall ~ look it up!!! but def a question


 * Power Required is more than Power Available with collective down ~ increase in descent rate


 * Ground Effect decreases ~ induced flow


 * Blowback will cause ~ nose to rise


 * proautorotation is ~ horizontal component of lift


 * low vibrations are caused by ~ main rotor


 * with an increase in density and a decrease in temp/humidity, PRESSURE does what? ~ look it up!!! but def a question