1. West Point Aviation Club Private Pilot Ground Instruction
Aerodynamics of Maneuvering Flight

2. Left-Turning Tendencies
Torque
Gyroscopic Precession
Asymmetrical Thrust
Spiraling Slipstream

3. 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

4. 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

5. Left-Turning Tendencies Gyroscopic Precession

6. 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

7. 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

8. 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?

9. Left-Turning Tendencies Aircraft Design Considerations
Some manufacturers include design elements to help counteract left-turning tendencies
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 left-turning tendency caused by spiraling slipstream

10. Climbing Flight
Transition from level to climbing flight: normally change in pitch attitude and increase in power
Excess thrust, not excess lift, needed for a climb

11. Descending Flight
In stabilized descending flight, aerodynamic forces are in equilibrium with the force of weight comprised of two components
One component of weight acts perpendicular to the flight path
The other component of weight acts along the flight path

12. Descending Flight
In stabilized powered descent, four aerodynamic forces are in equilibrium (top figure)
In stabilized descent with power at idle, three aerodynamic forces are in equilibrium with the forward component of weight equal and opposite to drag

13. 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

14. 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

15. 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

16. Factors Affecting the Glide
Weight
Configuration
Wind

17. Factors Affecting the Glide 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
The heavier aircraft will sink faster and will reach the ground sooner, it will travel the same distance as the lighter one

18. Factors Affecting the Glide Configuration
If you increase drag, the maximum lift-to-drag ratio and glide ratio are both reduced
To maintain the airspeed you had before your lowered gear, you’d have to lower the nose

19. Factors Affecting the Glide 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

20. 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

21. Turning Flight
To maintain altitude in a turn, you will need to apply backpressure, and therefore, angle of attack until 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

22. 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

23. 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

24. 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
If airspeed increases and angle of bank remains same, rate of turn decreases
Radius of turn refers to the amount of horizontal distance an aircraft uses to complete a turn

26. Load Factor
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
“G Force” same name; “pulling G’s”

27. 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

28. Load Factor and Stall Speed
Additional load factor incurred during constant altitude turns will also increase stall speed
Stall speed increases in proportion to the square root of the load factor
Stalls that occur with G forces are called accelerated stalls

29. 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

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