Flashcards in Block 2 Deck (51)
Tips on Using the VOR
• Positively identify the station by its code or voice
• Keep in mind that VOR signals are “line-of-sight.” A
weak signal or no signal at all is received if the aircraft
is too low or too far from the station.
• When navigating to a station, determine the inbound
radial and use this radial. Fly a heading that will
maintain the course. If the aircraft drifts, fly a heading
to re-intercept the course then apply a correction to
compensate for wind drift.
• If minor needle fluctuations occur, avoid changing
headings immediately. Wait momentarily to see if the
needle recenters; if it does not, then correct.
• When flying “TO” a station, always fly the selected
course with a “TO” indication. When flying “FROM” a
station, always fly the selected course with a “FROM”
indication. If this is not done, the action of the course deviation needle is reversed. To further explain this
reverse action, if the aircraft is flown toward a station
with a “FROM” indication or away from a station
with a “TO” indication, the course deviation needle
indicates in an direction opposite to that which it
should indicate. For example, if the aircraft drifts to
the right of a radial being flown, the needle moves to
the right or points away from the radial. If the aircraft
drifts to the left of the radial being flown, the needle
moves left or in the direction opposite to the radial.
• When navigating using the VOR it is important to fly
headings that maintain or re-intercept the course. Just
turning toward the needle will cause overshooting
the radial and flying an S turn to the left and right of
Time in seconds between bearings/Degrees of bearing change
=Minutes to station
Ex. If 2 minutes (120 seconds) is required to fly a
bearing change of 10 degrees, the aircraft is—
120/10= 12 Minutes
Four Forces of Flight
Four Forces of Flight -Interaction
•Steady Flight Condition - Equilibrium
–Lift = Weight
–Thrust = Drag
–Thrust exceeds Drag
–Drag exceeds Thrust
Angle of Incidence
•Angle formed by the chord line and longitudinal axis
Lift & How It's Created
•Lift provides the upward force which sustains the aircraft in flight
•The creation of lift is based on:
1. Bernoulli’s Principle
2. Newton’s 3rd Law of Motion
•L = ½ *ρ*V2*S*CL
–ρ = Air Density
–V = Velocity
–S = Surface Area of Wing
–CL = Coefficient of Lift
•As the velocity of a fluid increases the pressure of that fluid decreases
Newton’s 3rd Law of Motion
“To every force in nature there is a corresponding reaction force.”
Factors Affecting Lift
•Planform (size and shape)
–As air density decreases – lift decreases
–As velocity decreases – lift decreases
•Angle of attack
•Aspect Ratio – relationship between wingspan and average chord
Types of Planform
Aerodynamics of Flaps
–Extension of flaps increases the relative camber of the wing
–Change in Angle of Attack
–Change of Lift
–Change of Drag
Types of Wing Flaps
Wing Flaps – Effect of Use - Takeoff & Landing
–Allows aircraft to become airborne sooner
–Minimizes Ground Roll
–Allows for increased decent angle, steeper approach
–Approach can be flown as slower airspeed
–Ground roll reduced
Wing Flaps - Effect of Use - Lift & Drag
–Increases as AOA increases
–Drag increases as lift increases
Stall Occurs When:
Coefficient of lift is maximized as angle of attack is.
•The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.
What is a stall?
•Situation where airflow over the wing, which is typically smooth, becomes turbulent and separates from the wing.
–At this point the wing is no longer producing sufficient lift to sustain flight, resulting in a loss of altitude
Stalls – Design Factors
•Desirable for the wing to stall at the root first
–Allows roll control to be maintained for a longer period
Factors Affecting Stall Speed
•Angle of Bank / Load Factor
•Power / Thrust
•Frost / Snow / Ice
Load Factor and Stall Speed
•Stall speed will increase at a rate equal to the square root of the load factor
–Example: (not c172)
•Stall speed (Vs): 50 knots
•Bank the aircraft 50 degrees to create a load
factor of approximately 1.5 Gs.
•50 * 1.2 = 60
•Stall speed increased to 60 knots
Indications of Imminent Stalls
•Loss of Control Effectiveness
•Buffeting of Airframe
•Stall Warning Horn/Light
Situations Favorable for Stalls
•Takeoff Initial Climb (Power On Stall)
–Excessive pitch input during rotation
–Excessive pitch input during Best Angle Climb
•Approach Landing (Power Off Stall)
–Base to Final Turn
–Decrease Angle of Attack
–Level the wings
–Apply Full Power
–Regain Normal Flight
•Flaps 20º (if fully extended)
•Accelerate to Vx or Vy
•Retract Flaps to 0º slowly (if extended)
•Resume coordinated cruise flight
•When two masses are in contact they resist each others motion
•Air resists the aircrafts forward movement when the aircraft is in motion
•Drag is the resistance of the aircrafts movement though air
•Total Drag force is the result of different types of drag. Total Drag has two major classifications:
•Drag caused by the aircraft’s shape, construction type & material
•3 General Types of Parasite Drag
–Skin Friction Drag
Types of Parasite Drag
•Skin Friction Drag – result of the surface of the aircraft being rough
•Form Drag – result of an objects general shape
•Interference Drag – result of the interaction of airflow from joined components of the airframe
•Drag associated with the production of lift.
•Force which acts to move the aircraft forward
•Created by propeller
•Force resulting from Gravity
•Weight acts directly toward the center of the Earth at all times
•Acts at the aircrafts Center of Gravity
- Center of Gravity (CG) – the centroid of the sum of a mass
CG Effects - Forward CG
–More tail down force needed
CG Effects - Aft CG
–Less tail down force needed
Offset Lateral CG
Occurs when fuel from one tank is greater than the other
Aerodynamics of a Turn
•An aircraft turns by redirecting the lift created by the wings.
•All forces can be divided into Vertical and Horizontal Components. In level non-turning flight all lift is acting vertically and no lift is acting horizontally.
•In a turn a component of the total lift produced acts horizontally which is the force which turns the airplane.
Forces of a Turn
–Vertical Component of Lift
–Horizontal Component of Lift
•Turn Performance is measured in two ways:
–Rate of Turn – the speed at which the heading of the aircraft changes
–Radius of Turn – the area covered by an aircraft in a turn
•The deflection of the ailerons in a turn have a tendency to pull the nose of the aircraft in the direction opposite the desired turn
•This yawing tendency outside of the turn is Adverse Yaw
Slips and Skid
•Slip – result of the horizontal component of lift being greater than the centrifugal force.
–Excessive Bank Angle
•Skid – result of the centrifugal force being greater than the horizontal component of lift.
–Insufficient Bank Angle
•Defined as an aggravated stall that results in ‘autorotation’.
•A Spin is the result of an aircraft stalling with a sideslip or yaw acting on the airplane.
•In a spin the aircraft is rotating about the Center of Gravity.
•The Flight Path in a spin is nearly vertical and is centered around the spin axis.
•The wing on the outside of the rotation is producing more lift sustaining the rotation of the aircraft
Stages of a Spin
2.Incipient – period where the aircraft begins spinning to where the forces of the spin are in equilibrium
1.Approx. 2 turns
3.Developed – period where the forces of a spin are in complete equilibrium to where control inputs are made to recover from spin
1.500 ft/3 sec turn
4.Recovery – period from corrective control input to return to normal flight
•When an aircraft is producing lift the pressure differential below and above the wing results in the production of Wingtip Vorticies
•If an aircraft is in too close proximity to these vorticies loss of aircraft control may result
Factors that affect Wake Turbulence
•as the velocity of an aircraft increases, the strength of the vorticies is reduced
•the heavier the aircraft the more lift that must be produced to sustain flight which increases vortex strength
–Angle of Attack
•higher angles of attack result in stronger vortices
•the clean configuration results in stronger vortices
–Aircraft Proximity to Ground
Strongest Wake Turbulence Occurs by plans that are :
Wake Turbulence Avoidance
Landing Behind Departing Aircraft?
Landing Behind Arriving Aircraft?
"FLY THE BOWL"
–Depart the surface prior to the departing aircrafts rotation point
–Remain above the departing aircrafts flight path
•Landing behind departing aircraft
–Plan touchdown prior to the departing aircrafts rotation point
•Landing behind arriving aircraft
–Plan touchdown after the arriving aircrafts touchdown point
•Ground Effect occurs when an aircraft is operating within a wingspan of the ground.
•The ground inhibits the development of the wingtip vortices which reduces the downwash created by the production of lift.
•This results in a decrease of Induced Drag which translates to increased performance when operating close to the surface.
Problems with Ground Effect:
Takeoff & Landing
•Takeoff – the aircraft will tend to depart the surface without having sufficient airspeed for sustained flight
- Ensure that a sufficient airspeed has been achieved prior to rotation
•Landing – when the airspeed is excessive at landing the aircraft will tend to “balloon” or “float”.
- Ensure that the appropriate airspeed is maintained throughout the pattern and on final
Left Turning Tendencies - What is it?
•The reaction of the airframe to the operation of the engine and propeller in a single engine airplane is a tendency to turn to the left.
•These left turning tendencies are most noticeable at slow airspeeds and high power settings (Takeoff, Go Around, Slow Flight)
Design Compensation for the Left Turning Tendencies
Stability : Static & Dynamic
•Stability is the tendency for a mass to return to is original state of equilibrium when disturbed from that steady state.
•Static Stability – the immediate initial tendency of an aircraft when displaced
•Dynamic Stability – the tendency of an aircraft over time
Stability - Airplane Surfaces
Aileron - Rolls - Longitudinal Axes - Lateral Stability
Elevator/Stabilizer- Pitch - Lateral Axes - Longitudinal Stability
Rudder - Yaw - Vertical Axes - Directional Stability
Thrustline Placement : Above/Below CG
Above CG: Pitching Tendency Down
Below CG: Pitching Tendency UP