Uncontrolled copy not subject to amendment Principles of Flight Principles of Flight Learning Outcome 5: Be able to apply the principles of flight and control to rotary wing aircraft Part 1 Questions Name the Forces Acting on a Glider in Normal Flight. a. Force, Weight and Lift. b. Drag, Weight and Thrust. c. Drag, Weight and Lift. d. Drag, Thrust and Lift. Questions How does a Glider Pilot Increase the Airspeed? a. Operate the Airbrakes. b. Lower the Nose by pushing the Stick Forward. c. Raise the Nose by pulling the Stick Back. d. Lower the Nose by pulling the Stick Back. Questions A Viking Glider descends from 1640 ft (0.5 km). How far over the ground does it Travel (in still air)? a. 17.5 kms. b. 35 kms. c. 70 kms. d. 8.75 kms. Questions When flying into a Headwind, the distance covered over the ground will: a. Be the same. b. Decrease. c. Increase. d. No change. Propellers Objectives: 1. Define Blade Angle and Blade Angle of Attack. 2. Show with the aid of a diagram the Aerodynamic Forces acting on a Propeller Blade in flight. 3. Explain Aerodynamic and Centrifugal Twisting Moments acting on a propeller. 4. Explain the effect of changing forward speed on: a. A Fixed Pitch propeller. b. A Variable Pitch propeller. (and thus the advantages of a variable pitch propeller). 5. Explain the factors causing swings on take-off for: a. A Nose-Wheel aircraft. b. A Tail- Wheel aircraft. Propellers MOD Propellers (Terminology) Propellers (Terminology) Airflow due to Rotational Velocity Propellers (Terminology) Induced Flow Airflow due to Rotational Velocity Propellers (Terminology) Induced Flow Relative Airflow Airflow due to Rotational Velocity Propellers (Terminology) Induced Flow Chord Line Relative Airflow Airflow due to Rotational Velocity Propellers (Terminology) Induced Flow Chord Line = AofA Relative Airflow Airflow due to Rotational Velocity Propellers (Terminology) Induced Flow Chord Line Airflow due to Rotational Velocity Relative Airflow = AofA = Blade Angle Propellers Blade Twist Rotational Velocity Total Inflow Approx 4o Angle of Attack Effect of Airspeed Induced Flow Airflow due to Rotational Velocity At Zero Airspeed Effect of Airspeed TAS + - Induced Flow = Total Inflow Airflow due to Rotational Velocity (Same) At a Forward Airspeed Effect of Airspeed TAS + Induced Flow Airflow due to Rotational Velocity (Same) - At a Forward Airspeed Need larger for same = Total Inflow Effect of Airspeed _ 100% Fine _ Propeller 75% Efficiency _ at Max Power Coarse 50% 25% _ True Airspeed Pitch of Propeller Blade _ 100% Fine _ Variable Pitch Propeller 75% Efficiency _ at Max Power Coarse 50% 25% _ True Airspeed Why a different Number of Blades? Aerodynamic Forces Total Inflow RAF Airflow due to Rotational Velocity Aerodynamic Forces Total Inflow Total Reaction RAF Airflow due to Rotational Velocity Aerodynamic Forces Total Inflow RAF Drag Lift Total Reaction Airflow due to Rotational Velocity Aerodynamic Forces Total Inflow Thrust Total Reaction RAF Airflow due to Rotational Velocity Aerodynamic Forces Total Inflow RAF Thrust Total Reaction Prop Rotational Drag Airflow due to Rotational Velocity Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust Total Reaction Slow Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust Total Reaction High Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust Total Reaction High Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust Total Reaction High Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust NB: Rotational Drag reduced, RPM ? High Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust NB: Rotational Drag reduced, RPM increases. Don’t exceed limits. High Speed Fixed Pitch Aerodynamic Forces (Effect of High Speed) TAS+Induced Flow RAF Airflow due to Rotational Velocity Thrust Total Reaction Slow Speed Variable Pitch Aerodynamic Forces (Effect of High Speed) Faster TAS+Induced Flow RAF Thrust (eventually reduces) Total Reaction (same or possibly greater) Airflow due to Rotational Velocity High Speed Variable Pitch Windmilling Propeller Negative TAS Airflow due to Rotational Velocity Windmilling Propeller Negative TAS TR Airflow due to Rotational Velocity Windmilling Propeller Negative TAS TR Negative Thrust (Drag) Airflow due to Rotational Velocity Windmilling Propeller Negative TAS TR Negative Thrust (Drag) Negative Rotational Drag (Driving The Propeller) Airflow due to Rotational Velocity Windmilling Propeller Negative TAS TR Negative Thrust (Drag) Negative Rotational Drag (Driving The Propeller) This may cause further damage, even Fire. Airflow due to Rotational Velocity Feathered Propeller Although twisted, in aggregate, blade at “Zero Lift α”. Therefore drag at minimum. Note that in Firefly/Tutor prop goes to “Fine Pitch” if engine rotating, “Coarse Pitch” if engine seized Take-Off Swings All Aircraft: Torque Reaction means greater rolling resistance on one wheel Helical slipstream acts more on one side of the fin than the other Take-Off Swings Take-Off Swings Tail wheel aircraft only: Asymmetric blade effect Gyroscopic effect Take-Off Swings Take-Off Swings Affect all aircraft on rotate? Take-Off Swings All Aircraft: Don’t forget crosswind effect! Centrifugal Twisting Moment Tries to fine blade off Aerodynamic Twisting Moment Relative Airflow Total Reaction Tries to coarsen blade up Aerodynamic Twisting Moment Windmilling Total Reaction Relative Airflow Tries to fine blade off ANY QUESTIONS? Propellers Objectives: 1. Define Blade Angle and Blade Angle of Attack. 2. Show with the aid of a diagram the Aerodynamic Forces acting on a Propeller Blade in flight. 3. Explain Aerodynamic and Centrifugal Twisting Moments acting on a propeller. 4. Explain the effect of changing forward speed on: a. A Fixed Pitch propeller. b. A Variable Pitch propeller. (and thus the advantages of a variable pitch propeller). 5. Explain the factors causing swings on take-off for: a. A Nose-Wheel aircraft. b. A Tail- Wheel aircraft. Questions Blade Angle of Attack is between? a. The Chord and Relative Airflow. b. The Rotational Velocity and the Relative Airflow. c. The Total Reaction and the Chord. d. Lift and Drag. Questions Increasing speed with a fixed pitch propeller will? a. Be more efficient. b. Reduce efficiency. c. Make no difference. d. Increase the Engine speed. Questions The Forces trying to alter the Propeller Blade Angle of Attack are? a. ATM and CTM. b. CDM and ATM. c. CTM and REV. d. AOA and ATM. Questions The Resultant Forces that a Propeller produce are? a. Lift and Thrust. b. Thrust and Propeller Rotational Drag. c. Drag and Total Reaction. d. Drag and Thrust.