1. Theory of Flight Flight Performance

2. Reference
From the Ground Up Chapters 2.1.5, 2.1.6, 2.1.7: Flight Performance Factors, Airspeed Limitations, Mach Number Pages

3. Introduction
There are many factors that affect an aircraft’s flight performance. As well, the four forces are manipulated to be able to maneuver an aircraft.

4. Outline Flight Performance Factors Climbing, Gliding & Turns
Stalls, Spins & Spiral Dives
Load Factor & Airspeed

5. Torque In nose-engine aircraft, propeller
rotates clockwise (as seen by pilot)
Result: Roll to left (counterclockwise rotation from equal and opposite reaction)
Correction: Slight right-turning tendency built-in to aircraft

6. Asymmetric Thrust
At high angles of attack and high power setting (i.e. take-off), descending propeller blade has greater angle of attack than ascending blade
Right side of prop produces more thrust then left side
Result: Yaw to left
Correction: Use right rudder

7. Precession
Spinning propeller acts like a gyroscope: When force applied to spinning
gyro, force acts as if it was 90° in direction of rotation
Result:
Quick Nose-Up = Sharp yaw right
Quick Nose-Down = Sharp yaw left
Correction: Use opposite rudder
Tail-wheel aircraft prone to precession when nose pushed forward on take-off

8. Slipstream
Propeller pushes air back in corkscrew motion which hits left side of
fin (pushing it right)
Result: Constant yaw to left (depending on power setting)
Correction: Offset fin, trim, right rudder

9. Climbing
Ability to climb dependent on thrust: More thrust needed at higher altitudes
Thrust
Lift
Angle of Attack
Increase: More lift, less speed
Decrease: Less lift, more speed
Drag
Weight

10. Climbing Best Angle of Climb (Vx) Most altitude in least
- Shorter Time - Longer Distance
- Longer Time - Shorter Distance
Best Angle of Climb (Vx)
Most altitude in least
horizontal distance
(used for obstacles)
Best Rate of Climb (Vy)
Most altitude in least time
(used on normal take-off)
Normal Climb
Used during cruise

11. Gliding Gliding = 3 forces (Weight, Lift, Drag) Glide Reaction
= Resultant of lift and drag, opposes weight
Lift
Drag
Thrust = Horizontal component of weight
Weight

12. Gliding Best Range Speed Furthest distance per altitude lost
Best Endurance Speed Most time in air per altitude lost
- Longer Time - Shorter Distance
- Shorter Time - Longer Distance

13. Turns Vertical Component of Lift
Keeps aircraft in air (opposes weight)
Lift
Centripetal Force
Horizontal component of lift,
pulls aircraft into turn
Centrifugal Force
Imaginary force that
pulls aircraft outside of
turn (is really inertia)
Weight
Angle of Bank

14. Turns Shallow Bank Lesser turn rate Larger turn radius
Lower Stall Speed
Less Wing Loading
Steep Bank
Greater turn rate
Smaller turn radius
Higher Stall Speed
More Wing Loading

15. Turns Faster Airspeed Lesser turn rate Larger turn radius
Slower Airspeed
Greater turn rate
Smaller turn radius
Same bank angle

16. Turns Load Factors in Turns Angle of bank increase
= Load factor increase
60° bank = 2 G's
Dangers
High load factor
= Possible structural failure (overload)
Increased load factor
= Increased stall speed

17. Stalls Definition: Wing can’t create enough lift to support weight
When Critical Angle of Attack (Stall Angle) reached, turbulent airflow surpasses laminar airflow on wing
C of P rapidly moves towards trailing edge
Aircraft can stall at any airspeed or attitude if critical angle of attack is exceeded
Aircraft will stall at same indicated airspeed regardless of altitude

18. Factors Affecting Stall
Weight
More weight = higher angle of attack (closer to stall angle)
C of G
Forward = higher stall speed
Rearward = lower stall speed
Turbulence
Upward vertical gust could cause aircraft to exceed stall angle
Turns
Angle of bank increase = Stall speed increase (load factor/weight)
Flaps
Increasing lifting potential of wing = Stall speed decrease
Aircraft Condition
Snow, Frost, Ice, Dents = Disrupted laminar flow (increases stall speed)

19. Spins Definition: Auto-rotation which develops after aggravated stall
When wing drops in stall:
Down-going wing has greater angle of attack
Wing receives less lift, drops more rapidly
Drag on down-going wing increases, further increasing angle of attack
Wing stalls further, nose drops, auto-rotation starts

20. Spins

21. Spiral Dives
Definition: Steep descending turn in which airplane has excessive nose down attitude
Characteristics:
Excessive angle of bank
Rapidly increasing airspeed
Rapidly increasing rate of descent
Structural damage can occur if airspeed increases beyond limits

22. Spiral Dives

23. Spins vs Spiral Dives Spin: Spiral Dive: Aircraft stalled
Airspeed constant and low
Spiral Dive:
Aircraft not stalled
Airspeed increasing rapidly

24. Airspeed Limits Never Exceed Speed (VNE) Normal Operating Speed (VNO)
Max speed airplane can be operated in smooth air
Normal Operating Speed (VNO)
Design cruise speed, should not be intentionally exceeded
Maneuvering Speed (VA)
Max speed at which flight controls can be fully deflected without damage to structure
Maximum Flaps Extended Speed (VFE)
Max speed at which full flaps can be used

25. Mach Number
Ratio of speed of body to speed of sound (in air surrounding body)
Mach 1 = Speed of sound
Varies with air temperature, pressure and density

26. Next Lesson
2.5 - Theory of Flight Flight Instruments From the Ground Up Chapter 2.2: Pages