Aerodynamics (part 1)

Question 1

What are the four dynamic forces that act on an airplane during all maneuvers? (FAA-H-8083-25)

Answer 1

1. Lift
2. Gravity
3. Thrust
4. Drag

Question 2

What flight condition will result in the sum of the opposing forces being equal? (FAA-H-8083-25)

Answer 2

1. Steady-state, straight-and-level, unaccelerated flight
2. The four forces are equal to and cancel each other out

Question 3

What is an airfoil? (FAA-H-8083-25)

Answer 3

1. An airfoil is a device which gets a useful reaction from air moving over its surface, namely LIFT

Question 4

What is the angle of incidence? (FAA-H-8083-25)

Answer 4

1. The angle of incidence is the angle formed by the longitudinal axis of the airplane and the chord line of the wing
2. The angle of incidence is fixed and cannot be changed by the pilot

Question 5

What is a relative wind? (FAA-H-8083-25)

Answer 5

1. The relative wind is the direction of the airflow with respect to the wing

Question 6

What is the angle of attack? (FAA-H-8083-25)

Answer 6

1. The angle of attack is the angle between the wing chord line and the direction of the relative wind
2. It can be altered by the pilot

Question 7

What is Bernoulli’s Principle? (FAA-H-8083-25)

Answer 7

1. The pressure of a fluid decreases at points where the speed of the fluid increases
2. In the case of airflow, high speed flow is associated with low pressure and low speed flow with high pressure

Question 8

What are several factors which will affect both lift and drag?

Answer 8

1. Wing area
2. Shape of the airfoil
3. Angle of attack
4. Velocity of the air
5. Air density

Question 9

What is torque effect? (FAA-H-8083-25)

Answer 9

1. Newton’s Third Law of Physics states: for every action, there is an equal and opposite reaction
2. Torque effect means that as the internal engine parts and the propeller are revolving in one direction, an equal force is trying to rotate the airplane in the opposite direction
3. It is greatest when at low airspeeds with high power settings and a high angle of attack

Question 10

What effect does torque reaction have on an airplane in flight? (FAA-H-8083-25)

Answer 10

1. Torque reaction acts around the longitudinal axis, tending to make the airplane roll
2. To compensate, some older airplanes are rigged in a manner to create more lift on the wing that is being forced downward, while modern airplanes are designed with the engine offset to counteract this effect of torque

Question 11

What are the four factors that contribute to torque effect? (FAA-H-8083-25)

Answer 11

1. Torque reaction of the engine and propeller. The rotation of the propeller (from the cockpit) to the right, tends to roll or bank the airplane to the left
2. Gyroscopic effect of the propeller. If the axis of a propeller is tilted, the resulting force will be exerted 90° ahead in the direction of rotation
3. Corkscrewing effect of the propeller slipstream. High-speed rotation of an airplane propeller results in a corkscrewing rotation to the slipstream as it moves rearward
4. Asymmetrical loading of the propeller (P-Factor). When an airplane is flying with a high angle of attack, the bite of the downward moving propeller blade is greater than the bite of the upward moving blade

Question 12

What is centrifugal force? (FAA-H-8083-25)

Answer 12

1. Centrifugal force is the “equal and opposite reaction” of the airplane to the change in direction

Question 13

What is load factor? (FAA-H-8083-25)

Answer 13

1. Load factor is the ratio of the total load supported by the airplane’s wing to the actual weight of the airplane and its contents
2. Refer to a load factor of three as 3 G’s

Question 14

For what two reasons is load factor important to pilots? (FAA-H-8083-25)

Answer 14

1. Because of overload on the aircraft structure
2. Because an increased load factor increases the stalling speed