Slide 1

Aerodynamic Theory Review 2 ATC Chapter 6 Slide 2 Aim To review turning and aircraft speed limitations Slide 3 Objectives 1.State the forces acting in a turn 2.Define rate and radius of turn 3.Describe overbanking tendency 4.Define adverse aileron yaw and state design features to minimise it 5.Define V code airspeeds and explain how they relate to aircraft operation Slide 4 1. Forces acting in a turn What are the forces acting on the aircraft during S+L? Lift Weight As AoB is increased the lift vector is tilted Lift Slide 5 LvLv LHLH Centripetal Force Centrifugal Force Weight 1. Forces acting in a turn This creates a vertical and horizontal component of lift (centripetal force), we can see however that the vertical component of lift is no longer equal to weight In order to maintain level flight we must increase our total lift, this increases both the vertical and horizontal components of lift Slide 6 Lift LvLv LHLH Centripetal Force Centrifugal Force Load Factor Weight 1. Forces acting in a turn Equal and opposite to our lift is the load factor Equal and opposite to our centripetal force is the centrifugal force Slide 7 Lift LvLv LHLH Centripetal Force Centrifugal Force Load Factor Weight 1. Forces acting in a turn In summary:L > W Lv = WLv = W L = Load Factor Centripetal force = Centrifugal force Slide 8 Rate of Turn Alteration of HDG per unit time Rate 1 = 360 o /2min 3 o /sec Radius of Turn Distance from centre of turn to the aircraft 2. Define Rate & Radius Slide 9 Rate of Turn Rate of Turn = (Degrees/Second) Velocity increases, Rate decreases AoB increases, Rate increases 2. Define Rate & Radius 1091 x tan V Slide 10 Radius of Turn Radius of Turn = (Feet) Velocity increases, Radius increases AoB increases, Radius decreases 2. Define Rate & Radius V 2 ____ 11.26 x tan Slide 11 3. Overbanking Tendency Outer wing travels a further distance in the same time as inner wing Faster speed = More lift = Overbanking L = C L. 1 / 2..V 2. S Outer wing vs. inner wing Slide 12 When the aileron on the up going wing is deflected it creates more lift, it also creates more drag This imbalance in drag causes the nose of the aircraft to yaw in the opposite direction to the roll Adverse yaw only occurs when the ailerons are deflected This is why we apply rudder in the same direction when we apply aileron 4. Adverse Aileron Yaw Definition Slide 13 4. Adverse Aileron Yaw Differential Ailerons When the control column is rotated the up going aileron travels through a greater arc than the down going This will increase the drag produced by the up going aileron (which is on the inner wing) and reduce the drag difference between each wing, reducing adverse yaw Down going aileron- Outer wing Up going aileron- Inner wing Slide 14 4. Adverse Aileron Yaw Frise-type Ailerons The inner edge of the up going aileron protrudes into the airflow beneath the wing, disturbing the airflow resulting in an increase in drag on the inner wing This increase in drag on the inner wing will reduce the drag difference between each wing, reducing adverse yaw Down going aileron- Outer wing Up going aileron- Inner wing Slide 15 The rudder is automatically altered when the ailerons are applied 4. Adverse Aileron Yaw Coupled ailerons & rudder The rudder is deflected to the direction of turn The subsequent yaw in the direction of the turn counters adverse aileron yaw i.e. Left turn = left rudder Slide 16 Expressed in terms of the aircraft's indicated airspeed 5. V Code Airspeeds What is the V Code? Commonly used and most safety-critical airspeeds are displayed as color- coded arcs and lines located on the face of an aircraft's airspeed indicator Specific to a particular model of aircraft A standard terms used to define airspeeds important to the operation of all aircraft Derived from data obtained by aircraft designers and manufacturers during flight testing Slide 17 V X Maximum angle of climb speed 5. V Code Airspeeds Definitions V Y Maximum rate of climb speed V S0 Stall speed in the landing configuration V S Stall Speed V FO Maximum flap operation speed V S1 Stall speed in the cruise configuration V FE Maximum flap extended speed V A Maximum manoeuvring speed V B Maximum turbulence penetration speed V NE Never Exceed Speed V NO Maximum speed for normal operations V F Flap Speed V LO Maximum landing gear operation speed Slide 18 5. V Code Airspeeds V NE Never Exceed Speed Maximum speed under any circumstances Displayed on the airspeed indicator as a red line Situations that may result in the aircraft exceeding this speed: High speed descent Spiral Dive Slide 19 5. V Code Airspeeds V NO Maximum speed for normal operations Maximum speed for normal operations This speed may only be in smooth air and when justified by operational requirements Displayed on the airspeed indicator where the green arc changes to the yellow arc Situations that may result in the aircraft exceeding this speed: High speed descent Spiral Dive Slide 20 5. V Code Airspeeds V F Flap Speed V FE Maximum flap extended speed This limit is to prevent overstressing the flap structure Displayed on the airspeed indicator at the higher end of the white arc Situations that may result in the aircraft exceeding this speed: Too Fast on approach Not retracting the flaps after take off (if deployed) Not retracting the flaps in the event of a go-around Slide 21 5. V Code Airspeeds V F Flap Speed V FO Maximum flap operation speed This speed limit is only applicable when the flaps are in motion This airspeed limitation is not displayed on the airspeed indicator Situations that may result in the aircraft exceeding this speed: Not knowing the speed limitation Airspeed is found in the pilot operating handbook Not checking the speed prior to deploying the flaps Slide 22 5. V Code Airspeeds V S Stall Speed V S0 Stall speed in the landing configuration This is the lowest speed permissible in level flight in the landing configuration Situation that may result in the aircraft slowing to less than V s0 : The flare This airspeed limitation is displayed on the airspeed indicator at the lower end of the white arc There are a number of certification limits under which the stall speed for an aircraft is tested and certified to: MTOW Most forward CoG Power Idle 1G Flaps Retracted Slide 23 5. V Code Airspeeds V S Stall Speed V S1 Stall speed in the cruise configuration This is the lowest speed permissible in level flight Situation that may result in the aircraft slowing to less than V s0 : Climb This airspeed limitation is displayed on the airspeed indicator at the lower end of the green arc There are a number of certification limits under which the stall speed for an aircraft is tested and certified to: MTOW Most forward CoG Power Idle 1G Flaps Retracted Slide 24 5. V Code Airspeeds V X Maximum angle of climb speed The speed, during a climb, that gives the best altitude gain for the shortest horizontal distance This is the lowest climb speed that is used This speed is achieved at the maximum surplus between thrust available and thrust required To clear obstacles after take off This airspeed is not displayed on the airspeed indicator Situations that may require this climb speed: Airspeed is found in the pilot operating handbook Make an ATC requirement Slide 25 5. V Code Airspeeds V Y Maximum rate of climb speed The speed, during a climb, that gives the best altitude gain for the shortest time This is the climb speed that is primarily used This speed is achieved at the maximum surplus between power available and power required Normal take off This airspeed is not displayed on the airspeed indicator Situations that may require this climb speed: Airspeed is found in the pilot operating handbook Change in altitude Slide 26 5. V Code Airspeeds V A Maximum manoeuvring speed The highest speed at which full control deflection will not overstress the aircraft At or below V A the aircraft will stall before structural damage Spiral dive This airspeed is not displayed on the airspeed indicator Situations that may result in the aircraft exceeding this speed: Airspeed is found in the pilot operating handbook Uncorrected undesired aircraft states Slide 27 5. V Code Airspeeds V B Maximum turbulence penetration speed The highest speed permissible in turbulent air to avoid overstressing the aircraft Fast enough to prevent a gust causing a stall Not aware of weather conditions conducive to turbulence This airspeed is not displayed on the airspeed indicator Situations that may result in the aircraft exceeding this speed: Airspeed is found in the pilot operating handbook Not reducing speed in turbulence Slide 28 5. V Code Airspeeds V LO Maximum landing gear operation speed This speed limit is only applicable when the landing gear is in motion This airspeed limitation is not displayed on the airspeed indicator Situations that may result in the aircraft exceeding this speed: Not knowing the speed limitation Airspeed is found in the pilot operating handbook Not checking the speed prior to deploying the landing gear Slide 29 Questions?