Ground School Chapter 3 Aerodynamics of Flight 1

Ground School Chapter 3 Aerodynamics of Flight

1. The four forces acting on an airplane in flight are: a. lift, weight, thrust, and drag. b. lift, weight, gravity, and thrust. c. lift, gravity, power, and friction. 2. When are the four forces that act on an airplane in equilibrium? a. During unaccelerated flight. b. When the aircraft is at rest on the ground. c. When the aircraft is accelerating. 3. (Refer to figure 1. ) The acute angle A is the angle of a. Dihedral. b. Incidence. c. Attack.

4. The term "angle of attack" is defined as the angle a. formed by the longitudinal axis of the airplane and the chord line of the wing b. between the wing chord line and the relative wind. c. between the airplane's climb angle and the horizon. 5. What is the relationship of lift, drag, thrust, and weight when the airplane is in straight-and-level flight? a. Lift, drag, and weight equal thrust. b. Lift equals weight and thrust equals drag. c. Lift and weight equal thrust and drag. 6. How will frost on the wings of an airplane affect takeoff performance? a. Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability. b. Frost will change the camber of the wing, increasing its lifting capability. c. Frost will cause the airplane to become airborne with a higher angle of attack, decreasing the stall speed

7. In what flight condition is torque effect the greatest in a single-engine airplane? a. Low airspeed, high power, high angle of attack. b. High airspeed, high power, high angle of attack. c. Low airspeed, low power, low angle of attack. 8. The left turning tendency of an airplane caused by P-factor is the result of the a. gyroscopic forces applied to the rotating propeller blades acting 90° in advan of the point the force was applied. b. clockwise rotation of the engine and the propeller turning the airplane counter-clockwise. c. propeller blade descending on the right, producing more thrust than the ascending blade on the left. 9. When does P-factor cause the airplane to yaw to the left? a. When at high angles of attack. b. When at high airspeeds. c. When at low angles of attack.

10. An airplane said to be inherently stable will a. require less effort to control. b. be difficult to stall. c. not spin. 11. What determines the longitudinal stability of an airplane? a. The relationship of thrust and lift to weight and drag. b. The effectiveness of the horizontal stabilizer, rudder, and rudder trim tab. c. The location of the CG with respect to the center of lift. 12. What causes an airplane (except a T-tail) to pitch nosedown when power is reduced and controls are not adjusted? a. The downwash on the elevators from the propeller slipstream is reduced and elevator effectiveness is reduced. b. The CG shifts forward when thrust and drag are reduced. c. When thrust is reduced to less than weight, lift is also reduced and the wings can no longer support the weight

13. What is the purpose of the rudder on an airplane? a. To control yaw. b. To control overbanking tendency. c. To control roll. 14. (Refer to figure 2. ) If an airplane weighs 2, 300 pounds, what approximate weight would the airplane structure be required to support during a 60° banked turn while maintaining altitude? a. 4, 600 pounds. b. 2, 300 pounds. c. 3, 400 pounds. 15. (Refer to figure 2. ) If an airplane weighs 4, 500 pounds, what approximate weight would the airplane structure be required to support during a 45° banked turn while maintaining altitude? a. 4, 500 pounds. b. 7, 200 pounds. c. 6, 750 pounds.

16. The amount of excess load that can be imposed on the wing of an airplane depend upon the a. abruptness at which the load is applied. b. speed of the airplane. c. position of the CG. 17. Which basic flight maneuver increases the load factor on an airplane as compared to straight-and-level flight? a. Stalls. b. Climbs. c. Turns. 18. The angle of attack at which an airplane wing stalls will a. increase if the CG is moved forward. b. remain the same regardless of gross weight. c. change with an increase in gross weight.

19. During an approach to a stall, an increased load factor will cause the airplane to a. Have a tendency to spin. b. Stall at a higher airspeed. c. Be more difficult to control. 20. One of the main functions of flaps during approach and landing is to a. increase the angle of descent without increasing the airspeed. b. decrease the angle of descent without increasing the airspeed. c. permit a touchdown at a higher indicated airspeed. 21. What is one purpose of wing flaps? a. To relieve the pilot of maintaining continuous pressure on the controls. b. To decrease wing area to vary the lift. c. To enable the pilot to make steeper approaches to a landing without increasing the airspeed.

Question: An airplane said to be inherently stable will a. Be difficult to stall b. Require less effort to control c. Not spin 9

Question: An airplane said to be inherently stable will a. Be difficult to stall b. Require less effort to control c. Not spin 10

Question: Changes in the center of pressure of a wing affect the aircraft`s a. lift/drag ratio b. Lifting capacity c. Aerodynamic balance and controllability 11

Question: Changes in the center of pressure of a wing affect the aircraft`s a. lift/drag ratio b. Lifting capacity c. Aerodynamic balance and controllability 12

Question: What determines the longitudinal stability of an airplane? a. The location of the CG with respect to the center of lift b. The effectiveness of the horizontal stabilizer, rudder, and rudder trim tab c. The relationship of thrust and lift to weight and drag 13

Question: What determines the longitudinal stability of an airplane? a. The location of the CG with respect to the center of lift b. The effectiveness of the horizontal stabilizer, rudder, and rudder trim tab c. The relationship of thrust and lift to weight and drag 14

Question: What causes an airplane (except a T-tail) to pitch nosedown when power is reduced and controls are not adjusted? a. The CG shifts forward when thrust and drag are reduced b. The downwash on the elevator from the propeller slipstream is reduced and elevator effectiveness is reduced c. When thrust is reduced to less than weight, lift is also reduced and the wings can no longer support the weight. 15

Question: What causes an airplane (except a T-tail) to pitch nosedown when power is reduced and controls are not adjusted? a. The CG shifts forward when thrust and drag are reduced b. The downwash on the elevator from the propeller slipstream is reduced and elevator effectiveness is reduced c. When thrust is reduced to less than weight, lift is also reduced and the wings can no longer support the weight. 16

Question: An airplane has been loaded in such a manner that the CG is located aft of the aft CG limit. One undesirable flight characteristic a pilot might experience with this airplane would be a. A longer takeoff run b. Difficulty in recovering from a stalled condition c. Stalling at higher-than-normal airspeed 17

Question: An airplane has been loaded in such a manner that the CG is located aft of the aft CG limit. One undesirable flight characteristic a pilot might experience with this airplane would be a. A longer takeoff run b. Difficulty in recovering from a stalled condition c. Stalling at higher-than-normal airspeed 18

Question: Loading an airplane to the most aft CG will cause the airplane to be a. Less stable at all speeds b. Less stable at slow speeds, but more stable at high speeds c. Less stable at high speeds, but more stable at low speeds 19

Question: Loading an airplane to the most aft CG will cause the airplane to be a. Less stable at all speeds b. Less stable at slow speeds, but more stable at high speeds c. Less stable at high speeds, but more stable at low speeds 20

Question: In what flight condition must an aircraft be placed in order to spin? a. Partially stalled with one wing low b. In a steep diving spiral c. stalled 21

Question: In what flight condition must an aircraft be placed in order to spin? a. Partially stalled with one wing low b. In a steep diving spiral c. stalled 22

Question: During a spin to the left, which wing(s) is/are stalled? a. Both wings are stalled b. Neither wing is stalled c. Only the left wing is stalled 23

Question: During a spin to the left, which wing(s) is/are stalled? a. Both wings are stalled b. Neither wing is stalled c. Only the left wing is stalled 24

Left-Turning Tendencies • • Torque Gyroscopic Precession Asymmetrical Thrust Spiraling Slipstream

Left-Turning Tendencies Torque • Torque Effect is greatest at low airspeeds, high power settings, and high angles of attack • Newton’s Third Law: “For every action, there is an equal and opposite reaction” prop rotates clockwise, fuselage reacts counterclockwise

Left-Turning Tendencies Gyroscopic Precession • Turning prop exhibits rigidity in space and gyroscopic precession, like a gyroscope • Gyroscopic precession is the resultant reaction when a force is applied to the rim of a rotating disc • Reaction to a force occurs 90º later in the plane of rotation; only experienced when there is a change of aircraft attitude

Left-Turning Tendencies Gyroscopic Precession

Left-Turning Tendencies Asymmetrical Thrust • P-Factor causes an airplane to yaw to the left when it is at high angles of attack. P-Factor results from the descending prop blade on the right producing more thrust than the ascending blade on the left

Left-Turning Tendencies Spiraling Slipstream • As prop rotates, it creates a backward flow of air, or slipstream, which wraps around the airplane • The slipstream can cause a change in airflow around the vertical stabilizer; it strikes the lower left side of the vertical fin, resulting in a yaw to the left

Questions • Under what speed and power circumstances are the left turning tendencies most pronounced? • In what phases of flight do you encounter these speed and power circumstances?

Left-Turning Tendencies Aircraft Design Considerations • In small aircraft, often a metal tab on the trailing edge of the rudder that is bent to the left so pressure from the passing airflow will push on the tab and force the rudder slightly to the right • This slight right-hand rudder displacement creates a yawing moment that opposes the leftturning tendency caused by spiraling slipstream

Lift-to-Drag Ratio • Lift-to-drag ratio (L/D) can be used to measure the gliding efficiency of your airplane • The angle of attack resulting in the least drag on your airplane will give you the maximum lift-to-drag ratio (L/Dmax), the best glide angle, and the maximum gliding distance

Glide Speed • At a given weight, L/Dmax will correspond to a certain airspeed • This speed correlates to your best glide speed (maximum horizontal distance for altitude lost) • If power failure occurs after takeoff, immediately establish the proper gliding attitude and airspeed

Glide Ratio and Angle • Glide Ratio represents the distance an airplane will travel forward, without power, in relation to altitude loss • Example, 10: 1 means aircraft will travel 10, 000 feet of horizontal distance for every 1, 000 feet loss of altitude • Glide Angle is the angle between the actual glide path of your airplane and the horizontal; glide angle increases as drag increases

Factors Affecting the Glide • Weight • Configuration • Wind

Factors Affecting the Glide Weight • Weight – Variations in weight do not affect the glide ratio, however there is a specific airspeed that is optimum for a given weight – Two aerodynamically identical aircraft with different weights can glide the same distance from the same altitude; can only be done if the heavier aircraft flies at a higher airspeed than the lighter

Factors Affecting the Glide Configuration • Configuration – If you increase drag, such as by lowering landing gear, the maximum lift-to-drag ratio and glide ratio are both reduced

Factors Affecting the Glide Wind • Wind – A headwind will always reduce your glide range while a tailwind will always increase your glide range – In a strong headwind or tailwind (winds > 25% of glide speed), best glide may not be found at L/Dmax, and you may have to make adjustments to maximize your travel over the ground

Turning Flight • For an airplane to turn, must overcome inertia, or tendency to continue in a straight line • We create the necessary force by using the ailerons to bank the airplane so that the direction of total lift is inclined • The horizontal component of lift causes an airplane to turn

Turning Flight • To maintain altitude in a turn, you will need to apply backpressure and pitch up, until your vertical component of lift = weight • Horizontal component of lift creates force toward center of rotation; centripetal force • Opposite force, centrifugal force; not a true force; apparent force resulting from effect of inertia during turn

Turning Flight Adverse Yaw • Adverse yaw is the yawing tendency toward the outside of a turn • It is caused by higher induced drag on the outside wing, which is producing more lift • Need to apply rudder into the turn to control adverse yaw • Adverse yaw is greatest at high angles of attack and with large aileron deflection

Turning Flight Overbanking Tendency • As you enter a turn and increase the angle of bank, you may notice the tendency of the airplane to continue rolling into a steeper bank • Overbanking tendency is caused by the additional lift on the outside, or raised wing • Counteract overbanking tendency with small amount of opposite aileron

Turning Flight Rate and Radius of Turn • Rate of turn refers to the amount of time it takes for an airplane to turn a specific number of degrees • Radius of turn refers to the amount of horizontal distance an aircraft uses to complete a turn • If airspeed increases and angle of bank remains same -- rate of turn decreases, and radius of turn increases

Load Factor (G) • Load factor is the ratio of the load supported by the airplane’s wings to the actual weight of the aircraft and its contents • Aircraft in cruising flight, while not accelerating in any direction, has a load factor of one. The wings only supporting its own weight and contents • If wings are supporting twice as much weight as the weight of the airplane and its contents, the load factor is two

Load Factor in Turns • During constant altitude turns, the relationship between load factor, or G’s, and bank angle is the same for all airplanes • In a 60º bank, 2 G’s are required to maintain level flight

Load Factor and Stall Speed • Additional load factor incurred during constant altitude turns will also increase stall speed • Stalls that occur with G forces are called accelerated stalls

Limit Load Factor • Limit load factor is the amount of stress or load factor that an airplane can withstand before structural damage or failure occurs • Usually expressed in terms of G’s

Maneuvering Speed • Design Maneuvering Speed, or VA, represents the max speed at which you can use full, abrupt control movement without overstressing the airframe

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Question: If an airplane weighs 2, 300 pounds, what approximate weight would the airplane structure be required to support during a 60° banked turn while maintaining altitude? a. 2, 300 pounds b. 3, 400 pounds c. 4, 600 pounds 55

Question: If an airplane weighs 2, 300 pounds, what approximate weight would the airplane structure be required to support during a 60° banked turn while maintaining altitude? a. 2, 300 pounds b. 3, 400 pounds c. 4, 600 pounds 56

Question: If an airplane weighs 3, 300 pounds, what approximate weight would the airplane structure be required to support during a 30° banked turn while maintaining altitude? a. 1, 200 pounds b. 3, 100 pounds c. 3, 960 pounds 57

Question: If an airplane weighs 3, 300 pounds, what approximate weight would the airplane structure be required to support during a 30° banked turn while maintaining altitude? a. 1, 200 pounds b. 3, 100 pounds c. 3, 960 pounds 58

Question: If an airplane weighs 4, 500 pounds, what approximate weight would the airplane structure be required to support during a 45° banked turn while maintaining altitude? a. 4, 500 pounds b. 6, 750 pounds c. 7, 200 pounds 59

Question: If an airplane weighs 4, 500 pounds, what approximate weight would the airplane structure be required to support during a 45° banked turn while maintaining altitude? a. 4, 500 pounds b. 6, 750 pounds c. 7, 200 pounds 60

Question: Which basic flight maneuver increases the load factor on an airplane as compared to straight-and-level flight? a. Climbs b. Turns c. Stalls 61

Question: Which basic flight maneuver increases the load factor on an airplane as compared to straight-and-level flight? a. Climbs b. Turns c. Stalls 62

Question: What force makes an airplane turn? a. The horizontal component of lift b. The vertical component of lift c. Centrifugal force 63

Question: What force makes an airplane turn? a. The horizontal component of lift b. The vertical component of lift c. Centrifugal force 64

Question: The angle of attack at which an airplane wing stalls will a. Increase if the CG is moved forward b. Change with an increase in gross weight c. Remain the same regardless of gross weight 65

Question: The angle of attack at which an airplane wing stalls will a. Increase if the CG is moved forward b. Change with an increase in gross weight c. Remain the same regardless of gross weight 66

Question: During an approach to a stall, an increased load factor will cause the aircraft to a. Stall at higher airspeed b. Have a tendency to spin c. Be more difficult to control 67

Question: During an approach to a stall, an increased load factor will cause the aircraft to a. Stall at higher airspeed b. Have a tendency to spin c. Be more difficult to control 68

Question: Select the four flight fundamentals involved in maneuvering an aircraft. a. Aircraft power, pitch, bank, and trim b. Starting, taxing, takeoff, and landing c. Straight-and-level flight, turns, climbs, and descents 69

Question: Select the four flight fundamentals involved in maneuvering an aircraft. a. Aircraft power, pitch, bank, and trim b. Starting, taxing, takeoff, and landing c. Straight-and-level flight, turns, climbs, and descents 70

Question: Wingtip vortices are created only when an aircraft is a. Operating at high airspeeds b. Heavily loaded c. Developing lift 71

Question: Wingtip vortices are created only when an aircraft is a. Operating at high airspeeds b. Heavily loaded c. Developing lift 72

Question: The greatest vortex strength occurs when the generating aircraft is a. light, dirty, and fast b. Heavy, dirty, and fast c. Heavy, clean, and slow 73

Question: The greatest vortex strength occurs when the generating aircraft is a. light, dirty, and fast b. Heavy, dirty, and fast c. Heavy, clean, and slow 74

Question: Wingtip vortices created by large aircraft tend to a. Sink below the aircraft generating turbulence b. Rise into the traffic pattern c. Rise into the takeoff or landing path of a crossing runway 75

Question: Wingtip vortices created by large aircraft tend to a. Sink below the aircsaft generating turbulence b. Rise into the traffic pattern c. Rise into the takeoff or landing path of a crossing runway 76

Question: The wind condition that requires maximum caution when avoiding wake turbulence on landing is a a. light, quartering headwind b. Light, quartering tailwind c. Strong headwind 77

Question: The wind condition that requires maximum caution when avoiding wake turbulence on landing is a a. light, quartering headwind b. Light, quartering tailwind c. Strong headwind 78

Question: When landing behind a large aircraft, the pilot should avoid wake turbulence by staying a. Above the large aircraft’s final approach path and landing beyond the large aircraft’s touchdown point b. Below the large aircraft’s final approach path and landing before the large aircraft’s touchdown point c. Above the large aircraft’s final approach path and landing before the large aircraft’s touchdown point 79

Question: When landing behind a large aircraft, the pilot should avoid wake turbulence by staying a. Above the large aircraft’s final approach path and landing beyond the large aircraft’s touchdown point b. Below the large aircraft’s final approach path and landing before the large aircraft’s touchdown point c. Above the large aircraft’s final approach path and landing before the large aircraft’s touchdown point 80

Question: When departing behind a heavy aircraft, the pilot should avoid wake turbulence by maneuvering the aircraft a. Below and downwind from the heavy aircraft b. Above and upwind from the heavy aircraft c. Below and upwind from the heavy aircraft 81

Question: When departing behind a heavy aircraft, the pilot should avoid wake turbulence by maneuvering the aircraft a. Below and downwind from the heavy aircraft b. Above and upwind from the heavy aircraft c. Below and upwind from the heavy aircraft 82