Oral Exam: Performance & Limitations

Question 1

What are the four dynamic forces that act on an airplane during all maneuvers?

Answer 1

Lift
Gravity
Thrust
Drag

Question 2

In what flight condition are the sum of the opposing forces equal?

Answer 2

In steady-state, straight and level, and unaccelerated flight, the sum of the opposing forces are equal to each other. They cancel each other out…

Question 3

What is an airfoil?

Answer 3

An airfoil is a device which gets a useful reaction from air moving over its surface, primarily LIFT.
Examples… Wings, horizontal tail surfaces, vertical tail surfaces, and propellers.

Question 4

What is the angle of incidence?

Answer 4

The angle formed by the longitudinal axis of the airplane and the chord line of the wing.

• Measured where the wing is attached to the fuselage.
• Fixed and not manipulated by the pilot.

Question 5

What is a relative wind?

Answer 5

The direction of the airflow with respect to the wing.

-When a wing is moving forward and downward, the relative wind moves backward and upward….

Question 6

What is the angle of attack?

Answer 6

The angle between the chord line of the wing and the direction of the relative wind.
-Not fixed and manipulated by the pilot.

Question 7

What is Bernoulli’s Principle?

Answer 7

The pressure of a fluid(liquid/gas) decreases at points where the speed of the fluid increases.

• High speed air flow is associated with low pressure and low speed airflow with high pressure.
• The airfoil of an aircraft creates lift because the slow air flowing below has a higher pressure than the fast moving air above it

Question 8

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

Answer 8

• Using flaps and or the ailerons. (increase)
• Icing will increase drag and decrease lift
• Increasing angle of attack will increase lift and drag until limit is reached
• An increase in speed(air velocity) will increase lift and drag
• Air density
• increase causes lift and drag to increase
• decrease causes lift and drag to decrease

Question 9

What is torque effect?

Answer 9

Newton - for every action, there is an equal and opposite reaction…

• A left turning tendency… As the engine turns the propeller to the right, an equal force is applied in the opposite direction to the left.
• It is the greatest when at low airspeeds with high power settings and at high angles of attack.

Question 10

How does the airplane react to torque effect on the ground and in the air?

Answer 10

Ground: During the takeoff roll, the left side of the plane is being forced down by the torque. The additional force on the left wheel causes friction and drag turning the plane to the left. (Counter with right rudder)

In flight: The plane will roll/bank to the left at low speeds with high power settings like on takeoff or climbing with a high angle of attack. (Use more right rudder)

Question 11

What are the 4 left turning tendencies??

Answer 11

Torque effect
Spiraling slipstream effect
P-Factor
Gyroscopic Precession

Question 12

What is the spiraling slipstream effect?

Answer 12

The propeller creates a spiral of air that flows around the fuselage and strikes the left side of the vertical stabilizer/rudder…
-The force increases as power increases and causes the plane to yaw to the left.

Question 13

What is P-Factor?

Answer 13

The propeller is essentially an airfoil that produces lift. As the propeller spins clockwise, the descending blade on the right has a higher angle of attack creating more lift, yawing the plane to the left…
-This is more noticeable at higher power settings in a nose high attitude.

Question 14

What is gyroscopic precession?

Answer 14

A spinning propeller acts as a gyroscope and force applied to it is manifested 90 degrees ahead in the direction of the rotation. When a taildragger is on takeoff roll and the tail raises, this applies a downward force on the top of the propeller. This force is manifested 90 degrees to the right, which ends up pushing the nose to the left.

Question 15

What is centrifugal force?

Answer 15

The equal and opposite reaction of the airplane to the change in direction. It acts equal and opposite to the horizontal component of lift. (The apparent outward force on an object when it is rotated.)

Question 16

What is load factor?

Answer 16

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. Also expressed as the ratio of a given load to the pull of gravity.

*Centrifugal force experienced during curved flight increases the load factor of the plane.

Question 17

For what 2 reasons is load factor important to pilots?

Answer 17

1) Because of the obviously dangerous overload that it is possible for a pilot to impose on the aircraft structure.
2) Because an increased load factor increases the stalling speed and makes stalls possible at seemingly safe flight speeds.

Question 18

What situations may result in load factors reaching the maximum or being exceeded?

Answer 18

Level Turns:
Load factor increases exponentially after a bank has reached 45 or 50 degrees. Load factor is 2Gs in a 60 degree bank turn. At 80 degrees it is 5.76Gs (The wing must produce lift equal to these load factors if altitude is to be maintained)

Turbulence:
Severe vertical gusts cause a sudden increase in angle of attack, resulting in large loads which are resisted by the inertia of the airplane.

Speed:
The amount of excess load that can be imposed upon the wing depends on how fast the airplane is flying. At speeds below maneuvering speed, the airplane will stall before load factor can become excessive. When above maneuvering speed, the limit load factor for which an airplane is stressed can be exceeded by abrupt or excessive application of the controls or by strong turbulence.

Question 19

What are the different operational categories for aircraft and within which category does your aircraft fall?

Answer 19

Normal…… Load factor: +3.8 to -1.52
Utility……… Load Factor: +4.4 to -1.76
Aerobatic……. Load Factor: +6.0 to -3.00

Question 20

what effect does an increase in load factor have on stalling speed?

Answer 20

As load factor increases, stalling speed increases. Load factor increases as angle of attack increases. Any airplane can be stalled at any airspeed…. (Stalling speed increases in proportion to the square root of the load factor…)

Question 21

What is maneuvering speed?

Answer 21

Maneuvering Speed is the maximum speed at which the limit load can be imposed (either by gusts/turbulence or full deflection of the control surfaces) without causing structural damage.

• The speed below which, in smooth air, a pilot can fully deflect ONE flight control without risk of damaging the structure of the airplane.
• Speeds up to maneuvering speed allow an aircraft to stall prior to experiencing an increase in load factor that would exceed the limit load of the aircraft.

Question 22

What effect does an increase/decrease in weight have on maneuvering speed?

Answer 22

Maneuvering speed increases with an increase in wight and decreases with a decrease in weight.

Question 23

Define “loss-of-control-inflight” (LOC-I)…

What are several situations that might increase the risk of an LOC-I accident occurring.

Answer 23

(LOC-I) is defined as a significant deviation of an aircraft from the intended flight path and if often results from an airplane upset.

• Maneuvering is the most common phase of flight for LOC-I accidents to occur, but they do occur in all phases of flight.
• uncoordinated flight, equipment malfunctions, pilot complacency, distractions, turbulence, and poor risk management increase the risk of an LOC-I accident.

Question 24

What causes an airplane to stall?

Answer 24

The direct cause of every stall is an excessive angle of attack. Each plane has a particular critical angle of attack where the airflow separates from the upper surface of the wing and a stall occurs, usually 16 to 20 degrees.

Question 25

what is a spin?

Answer 25

A spin is either a controlled(recoverable) or uncontrolled(possibly unrecoverable) maneuver in which the airplane or glider descends in a helical path while flying at an angle of attack greater than the critical angle of attack. Spins result from aggravated stalls in other a slip or a skid. A spin cannot occur if a stall hasn’t occurred.

Question 26

what causes a spin?

Answer 26

The primary cause of an inadvertent spin is exceeding the critical angle of attack while applying excessive or insufficient rudder. This causes one wing to be stalled more than the other.

Question 27

when are spins most likely to occur?

Answer 27

• Engine failure on takeoff during climb out - pilot tries to stretch glide to landing area by increasing back pressure or makes an uncoordinated turn back to departure runway at low airspeed.
• Crossed-control turn from base to final (Slipping or skidding turn) pilot overshoots final and makes uncoordinated turn a low airspeed.
• Engine failure on approach to landing = pilot tries to stretch glide to runway by increasing back pressure
• Go-around with full nose-up trim = pilot applies power with full flaps and nose-up trim combined with uncoordinated use of rudder.
• Go-around with improper flap retraction = pilot applies power and fully retracts flaps too soon resulting in a rapid sink rate and an instinctive increase in back pressure.

Question 28

What procedure should be used to recover from an inadvertent spin?

Answer 28

P - Power reduced to idle
A - Ailerons positioned to neutral
R - Rudder apply full opposite of rotation
E - Elevator apply positive/forward of neutral movement to break stall.

-once the spin stops, neutralize the rudder and apply back pressure and throttle to return to level flight.

Question 29

What causes adverse yaw?

Answer 29

When turning an airplane to the left for example, the downward deflected aileron on the right produces more lift and drag on the right wing. The extra drag and lift on the right wing initially pulls the nose to the right instead of to the desired direction to the left…

Question 30

What is ground effect?

Answer 30

A condition of improved performance experienced when operating near the ground. Operating close to the ground (usually a distance equivalent to the wingspan) reduces the wing’s upwash, downwash, and wingtip vortices. This increases lift and reduces drag.

Question 31

What major problems can be caused by ground effect?

Answer 31

During Landing = Lift is increased and drag can be decreased by 40% when one-tenth a wingspan above the surface causing the airplane to excessively float down the runway without landing. It is possible to run out of runway and options….

During takeoff = Due to increased lift and a decrease in drag, the aircraft seems capable of takeoff well below the recommended speed. If the pilot climbs out of ground effect too soon, airspeed is too slow and induced drag increases making climb out difficult or not possible and the plane will fall back to the runway. This is especially concerning when high temperatures are present, there is high density altitude, or the plane is operating at a high gross weight.

Question 32

Define empty weight….

Answer 32

The weight of the airframe, engines, all permanently installed equipment, and unusable fuel. Depending on certification, either untrainable oil or full reservoir of oil is included.

Question 33

Define gross weight….

Answer 33

The maximum allowable weight of both the airplane and its contents.

Question 34

Define Useful load

Answer 34

The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil.

Question 35

Define Arm

Answer 35

The horizontal distance in inches from the reference datum line to the center of gravity of the item.

Question 36

Define Moment

Answer 36

The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches.

Question 37

Center of Gravity

Answer 37

The point about which an aircraft would balance if it were possible to suspend it at that point. expressed in inches from datum.

Question 38

Define datum

Answer 38

An imaginary vertical plane or line from which all measurements of arm are taken. Established by the manufacturer.

Question 39

What characteristics will be adversely affected when an aircraft has been overloaded?

Answer 39

• higher takeoff speed
• longer takeoff run
• reduced rate and angle of climb
• lower maximum altitude
• shorter range
• reduced cruising speed
• reduced maneuverabliity
• higher stalling speed
• higher landing speed
• longer landing roll
• excessive weight on the nose wheel

Question 40

What effect does a forward center of gravity have on an aircrafts flight characteristics?

Answer 40

Higher stalling speed - stalling angle of attack is reached at a higher speed due to increased wing loading.

Slower cruise speed - increased drag, greater angle of attack is required to maintain altitude

More stable - increases longitudinal stability

Greater back elevator pressure required - longer takeoff roll, higher approach speeds and problems with landing flare.

Question 41

what effect does a rearward center of gravity have on an aircraft’s flight characteristics?

Answer 41

Lower stalling speed - less wing loading

Higher cruise speed - reduced drag, smaller angle of attack is required to maintain altitude.

Less stable - stall and spin recovery more difficult, the center of gravity is closer to the center of pressure, causing longitudinal instability.

Question 42

What factors affect the performance of an aircraft during takeoffs and landings?

Answer 42

Air density (density altitude)

Surface winds

runway surface

upslope or downslope of runway

weight

Question 43

Define Density altitude

Answer 43

Density altitude is pressure altitude corrected for nonstandard temperature.

Question 44

Define pressure altitude

Answer 44

The altitude indicated when the altimeter setting window is adjusted to 29.92(standard pressure). Used to compute density altitude, true altitude, true airspeed and other performance data.