1. Uncontrolled copy not subject to amendment
Principles of Flight

2. Principles of Flight
Learning Outcome 5: Be able to apply the principles of flight and control to rotary wing aircraft Part 2

3. REVISION

4. Questions Blade Angle of Attack is between?
a. The Chord and Relative Airflow.
b. The Rotational Velocity and the Relative Airflow.
The Total Reaction and the Chord.
Lift and Drag.

5. Questions Increasing speed with a fixed pitch propeller will?
a. Be more efficient.
b. Reduce efficiency.
Make no difference.
Increase the Engine speed.

6. Questions The Forces trying to alter the Propeller Blade
Angle of Attack are?
a. ATM and CTM.
b. CDM and ATM.
CTM and REV.
AOA and ATM.

7. Questions The Resultant Forces that a Propeller produce are?
a. Lift and Thrust.
Thrust and Propeller Rotational Drag .
Drag and Total Reaction.
d. Drag and Thrust.

8. Helicopters Objectives:
State the method of generating Lift for a Helicopter.
List and Describe the following:
Blades, Rotor Head, Pitch Angle, Collective Pitch,
Rotor Disc, Cyclic Pitch, Tail Rotor, Hand Throttle,
Torque Reaction.
Explain how a Helicopter achieves Horizontal Flight.
Describe the Operation of the following Controls:
The Collective.
The Cyclic.
The Yaw Pedals.
The Hand Throttle.

9. How does a Wing produce Lift?
Helicopters
How does a Wing produce Lift?
Do you remember the Wind-Tunnel?

10. + + - - Lift A C B Air enters at ‘A’.
On reaching ‘B’ it has increased in speed to get through the narrower gap.
At ‘C’ the air has returned to the same values as ‘A’.
If Speed increases then Pressure Drops & Vice Versa.
SO, HOW DOES THIS WORK AS A WING?
Air flowing past a stationary object.
Air blows from A to C through a restriction.
Air cannot be “stored” at B, so something else happens.
From A to B the airspeed increase and slows from B to C.
This affects the pressure of the air.
This is a complicated theory but all we need to know is that if the air speeds up when passing B then the air pressure drops.
Can discuss that the sum of the energies is constant.
Remember the 2 pieces of paper when blowing between?
Could mention a “Venturi”.

11. + + - - The Wing is now producing LIFT. Lift LIFT A C B
A Wing works in the same way as the “Wind-Tunnel”.
Because the air is faster over the top surface, then
the pressure is decreased.
The Wing is now producing LIFT.
Now cut the “wind tunnel in half and we have a wing, which works in the same way.
Replace the tunnel with a wing and the effect is the same.
Can discuss that when the curvature (camber) is greater then more lift is generated.
Now you know why it is not a good idea to stand close to a railway platform’s edge!

12. Helicopters Cross-sectional area of Blade is the same shape as a Wing.
So, instead of moving a Wing
through the air, how about we
rotate the ‘Wing’!
Cross-sectional area of Blade
is the same shape as a Wing.
The rotating ‘Wing’ is now
producing Lift

13. Helicopters Relative Airflow Angle of Attack
How does a Helicopter Climb and Descend?
Lift
Chord
Relative Airflow
Angle of Attack

14. Helicopters Increase AoA Relative Airflow Angle of Attack
Climbing – How can the ‘Wing’ produce more Lift?
Lift
Increase AoA
Chord
Chord
Relative Airflow
Angle of Attack

15. Helicopters Decrease AoA
Descending – How can the ‘Wing’ produce less Lift?
Lift
Decrease AoA
(Increasing or Decreasing Rotor Speed will also affect Lift Production).

16. Parts of a Helicopter
Blades
Tail Rotor
Rotor Head
Rotor Disc

17. Parts of a Helicopter

18. HELICOPTER CONTROLS 1. The Collective Pitch Lever.
2. The Hand Throttle.
3. The Cyclic Pitch Control.
4. The Tail Rotor Control (Yaw Pedals).

19. HELICOPTER CONTROLS

20. Controls
Cyclic

21. Controls
Collective

22. Controls
Yaw Pedals

23. Controls
Cyclic
Collective
Yaw Pedals

24. The Hand Throttle Hand Throttle
The Collective Pitch Lever often contains a
Hand Throttle (like on a motor bike).

25. The Collective Pitch Lever
Rotor Blade
All Blades are changed by the same Angle.

26. THE COLLECTIVE PITCH LEVER

27. Torque Reaction - Yaw Fuselage Torque Reaction
What can be done to stop this?

28. Torque Reaction - Yaw Airflow Balancing Force
A Tail Rotor is added to counter the Torque Reaction.
Which Control is used for this?

29. The Yaw Pedals Moving the Yaw Pedals will alter Blade Pitch
equally on all the Tail
Rotor Blades
Yaw Pedals
The Yaw Pedals can also be used to turn (yaw)
the Helicopter around the main Rotor.

30. Tail Rotors

31. Horizontal Flight
How does a Helicopter achieve this?

32. Horizontal Flight The ‘Disc’ is tilted,
Lift
Lift
Thrust
Thrust
The ‘Disc’ is tilted,
producing a horizontal component of Thrust.

33. Horizontal Flight The Rotor Disc can be tilted forward,
back, left, right depending on the
position of the Cyclic Control.

34. Horizontal Flight

35. Any Questions?

36. Helicopters Objectives:
State the method of generating Lift for a Helicopter.
List and Describe the following:
Blades, Rotor Head, Pitch Angle, Collective Pitch,
Rotor Disc, Cyclic Pitch, Tail Rotor, Hand Throttle,
Torque Reaction.
Explain how a Helicopter achieves Horizontal Flight.
Describe the Operation of the following Controls:
The Collective.
The Cyclic.
The Yaw Pedals.
The Hand Throttle.

37. Questions How does a Helicopter generate Lift?
Spinning the main rotor faster.
Spinning the main rotor slower.
Increasing the angle of attack of each rotor blade.
Decreasing the angle of attack of each rotor blade.

38. Questions When a Helicopter rotor is driven in a circular motion
there is an opposing force, what is this force called?
Lift.
Torque Reaction.
Lift Reaction.
Drag.

39. Questions What is the purpose of a Tail Rotor?
Counter Torque Reaction.
Reduce Drag.
Provide Thrust.
Control the Helicopter in the rolling plane.

40. Questions What are the 3 controls a Helicopter uses to control
the aircraft’s attitude?
Collective, Cyclic, Yaw Pedals.
Ailerons, Rudders.
Cyclic, Elevators, Throttle.
Yaw Pedals, Fin, Rotor.