Task F: Performance and limitations PPL ACS

What are some limitations of our aircraft?

• Airspeeds: VNE- never exceed, VNO- maximum structural cruising speed, VA- maneuvering speed VFE- maximum flap extended speed, VS- stall speed

• Service ceiling

• Absolute ceiling

• Engine limitations: 2700RPM , oil quantities

• Weight limitations

• Fuel limitations

• CG limitations

What is the difference between absolute ceiling vs. service ceiling?

Service ceiling is the height at which the maximum rate of climb is 100 feetper minute. Absolute ceiling is where the maximum rate of climb is 0 feet per minute. Absolute ceiling is higher

Describe Vx and Vy and how they differ

Vx is the speed at which the aircraft obtains the highest altitude in a given distance. Vy is the speed at which the aircraft obtains the highest altitude per unit of time. Vx is in reference to distance, whereas Vy is in reference to time.

What is maneuvering speed?

The maximum speed at which the limit load can be imposed without causing structural damage to the airplane.

How can you calculate the maneuvering speed for your aircraft?

Va = Vs × √n

Where:

• Vs = Stall speed (in the same configuration)

• n = Load factor limit (g-limit) for your aircraft category

Where would you find performance data for your specific airplane?

Performance data can be found under the “Performance” section in the POH.

What is the difference between Vs0 and Vs1?

Vs0 is the power-off stalling speed in the landing configuration whereas

Vs1 is the power-off stalling speed in the clean configuration.

How will the climb rate of an airplane differ on a hot vs. cold day?

Temperature has an inverse relationship with density. As temperature increases, the air becomes less dense. As temperature decreases, the air becomes denser. Therefore, on a hot day, the air is less dense, and climb performance decreases. On the other hand, when it is a cold day, the air is denser, causing increased climb performance.

How will our aircraft perform at a high elevation airport on a hot day?

Our aircraft will perform worse in comparison to the same plane departing an airport at sea level on a cool day due to the high density altitude.

What is Density Altitude?

Density altitude is pressure altitude corrected for nonstandard temperature.

Can we change the camber of our wing?

Yes, we can change the camber of our wing by extending or retracting our flaps.

What happens when we extend our flaps from a clean configuration to flaps full?

Lift is increased and induced drag is increased. This allows us to have steeper descents without increasing airspeed

What can we expect to happen if we are taking off from a runway with a .6% incline?

Take off roll distance will be increased.

How would you describe the Center of Gravity?

It is the point at which the aircraft would balance if suspended. Essentially, it is the theoretical point at which the weight of the airplane is concentrated.

What are some results of having a more AFT center of gravity?

Higher cruise speed Lower stall speed Less stable Adverse stall recovery

What are some results of having a more FORWARD center of gravity?

Slower cruise speed Higher stall speed More stable More favorable stall recovery

What is the purpose of maneuvering speed? The

purpose of maneuvering speed is so the plane will stall before reaching its limit load factor and damage the structural integrity of the aircraft. We want to fly at or below maneuvering speed in turbulent situations.

Why might our actual performance be different or worse than the manufacturer's performance charts and tables?

The performance charts and tables published by the manufacturer are obtained using test pilots with new aircraft. Actual performance by a student pilot in a rental aircraft may not be the same.

What are the four forces of flight?

Lift, weight, thrust, and drag

Describe the relationship between thrust and drag.

Thrust and drag are equal to each other when the airplane is at a constant airspeed. When decelerating the airplane, thrust is less than drag. When the airplane is accelerating, thrust is greater than drag

Describe the relationship between lift and weight.

Lift and weight are equal to each other when the airplane is at a constant altitude. When climbing (increasing altitude), lift is greater than weight. When descending (decreasing altitude), weight is greater than lift.

What are the two basic types of drag? Explain each type. Parasite and Induced drag.

Parasite drag is composed of all the forces that work to slow an airplane’s movement. There are different types of parasite drag which include form drag, interference drag, and skin friction drag. Form drag is generated due to the shape of the airplane, and the airflow surrounding it. Interference drag is generated due to the intersection of airstreams that create turbulence and restrict smooth airflow. Skin friction drag is generated by the aerodynamic resistance of air in contact with the surface of the airplane. Induced drag is a byproduct of lift. Essentially, the production of lift causes induced drag through wing tip vortices

What are wingtip vortices, and how do they form?

Wingtip vortices are the circular motion of air around the tip of an airplane’s wing. They form due to the pressure difference between the upper and lower surfaces of an airfoil. The pressure on top of the wing is low, and the pressure below the wing is high. Because the path of least resistance for air is towards the wing tip, and because high pressure always follows low pressure, vortices are formed around the wing tips.

What are the axes of flight, and what causes motion about them?

● Longitudinal - Goes from the nose of the aircraft through the tail. Ailerons move the aircraft about this axis using roll.

● Vertical - The vertical axis extends from the bottom of the aircraft through the top. The rudder controls movement through this axis using yaw.

● Lateral - The lateral axis extends from the left side of the aircraft to the right side. Pitch is controlled by the elevator or stabilator. All three axes act through the center of gravity of the aircraft.

Explain the relationship between the four forces of flight in straight-and-level, unaccelerated flight.

Thrust and drag are equal in forces, and weight and lift are equal to each other.

What are the four turning tendencies?

● Torque

● P-factor

● Gyroscopic precession

● Spiraling slipstream

Explain why rudder must be used in turns to maintain coordinated flight.

As the yoke is turned to enter a bank, the outboard aileron deflects downward to increase lift on that wing. The increased lift causes more induced drag on that wing which causes the nose to yaw towards the outside of the turn. To maintain coordinated flight, you must input rudder control towards the inside of the turn when entering it.

What design methods can be used to combat increased induced drag during turns?

● Differential ailerons - the “up” aileron raises higher than the other aileron goes “down.” This causes increased drag on the inside wing and helps combat adverse yaw from the induced drag on the outside wing.

● Frise-type ailerons - ailerons using Frise-type systems cause the aileron being raised to have the bottom portion of the control surface project into the air flowing below the wing. This causes an increase in drag on the inside wing.

● Coupled ailerons - Coupled ailerons have an “interconnect” between the rudder and ailerons which causes the rudders to automatically move when the controls are turned.

● Flaperons - Flaperons combine both aspects of flaps and ailerons. Flaperons not only act like conventional ailerons, but they also can be lowered like flaps.

Why must you apply a nose-up input to the controls while in turns?

As the aircraft rolls into a turn without a nose-up command, the total lift produced remains unchanged. The lift vector no longer points straight up, but off at an angle. The aircraft’s weight remains unchanged, and there is now not enough “vertical” lift to offset the weight of the aircraft. Nose up control inputs must be made to increase angle of attack to produce more lift to combat the loss of the vertical component of lift in turns