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36 Cards in this Set
- Front
- Back
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What is the definition of a stall?
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Condition in flight where an increase in AOA results in a decrease in C*L
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Laminar Flow
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Produces Lift
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Turbulent Flow
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Does not produce lift
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Define Boundary Layer
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Thin layer of air near the surface of an airfoil where air is affected by the air foil
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What area on a wing surface does air have the highest kinetic energy and the least amount of pressure above which the most lift is created?
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Max point of thickness
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what is produced in a boundary layer separation?
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Turbulent Flow
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What causes a turbulent Flow?
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Adverse Pressure Gradient
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What is the cause of an adverse pressure gradient?
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Low Pressure behind the max point of thickness
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what controls an adverse pressure gradient?
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Kinetic energy of the relative wind
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What is the impact of a High AOA on the boundary layer?
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1. kinetic energy decreases 2. Adverse pressure gradient increases 3. Boundary layer separation moves forward on the airfoil
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define Boundary Layer separation
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Point in streamline where airflow no longer adheres to the airfoil
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what is the impact of boundary layer separation?
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The Airfoil no longer produces lift sufficient to overcome weight
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What causes Boundary layer separation?
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High AOA
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Where does the stall region on the boundary layer separation start?
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C*LMAX
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What is constant for every airfoil and is measured in arbitrary units?
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Stall AOA
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Is Stall airspeed the same for all airfoils?
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No, it varies based on the airspeed and AOA
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What are the two key differences between Power-off and Power-on stalls?
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1.Vertical Component of thrust 2. Propeller Acceleration factor
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Define Power-off stalls
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Power setting: IDLE, High Stall Speed, Stall warning near stall, Right turning tendancy
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Define Power-on stalls
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Power setting: above IDLE, Lower Stall Speed, Stall warning above stall, Left turning tendancy
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Which stall has a RIGHT turning tendency?
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Power-off
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Which stall has a LEFT turning tendency?
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Power-on
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What factors affect stall speed?
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1. Gross weight 2. Altitude (air density) 3. Load Factor
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What happens to stall speed of an aircraft when the weight increases?
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Stall speed also increases
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What happens to stall airspeed when altitude increases?
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True stall speed increases but indicated stall speed stays the same
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Increased G-loading is equivalent to increasing the weight
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TRUE
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What must increase with increased bank angle?
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G-load, and stall speed
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How many Gs are required to maintain level flight in a 60 degree bank?
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2Gs
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How is Boundary Layer controlled?
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deflection of kinetic energy airflow from the bottom of an airfoil to the top of an airfoil
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What is the most common Boundary layer control device?
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Leading Edge Slats or Slats
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What are the two benefits of Boundary Layer Control?
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1. Increased maneuvering capabilities 2. Decreased landing speed and distance.
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In what order will you lose control surfaces in a stall?
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1. ailerons 2. Elevator 3. Rudder
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T-6A stall AOA
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18 units
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What is the cause of buffet in the stick during a stall?
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Turbulent airflow over the empannage
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When does the buffet occur in the T-6A for power-on and power-off stalls?
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Power-on - little natural effect of buffet before stall. Power-off - Approx 3 Knots before stall.
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What are the two indications in the T-6A of a stall?
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1. AOA gauge reading at 18 units 2. Stick Shaker
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When does the stick shaker activate in the T-6A?
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1. Approx. 15.5 AOA 2. minimum 5 knots before stall
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