Flashcards in Lift Production And Drag 2-2 Deck (44):

1

## Explain the Aerodynamic relationship of 4 Forces in Equilibrium Flight.

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Lift, Weight, Thrust, Drag.

Equilibrium flight when sum of all forces and moments are =Zero.

Lift acts against Weight and Drag acts against Thrust.

2

## Describe how the primary Aerodynamic Forces affect each other.

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AF- is the net force that results from Pressure and Shear Stress distribution over an Airfoil. And broken down int Lift and Drag.

*Pressure acts perpendicular to the body and Sheer Stress acts tangential to the surface.

**Lift=Pressure - Perpendicular to relative wind

**Drag= acting parallel to & same direction as relative wind.

3

##
State Pressure Distribution around an Airfoil, Given changes in AOA and Camber.

**unanswered**

### Increasing AOA results a continued reduction of the cross-sectional area of the stream tube flowing over the top surface resulting in more lift being created.

4

## Define Lift.

### The component of the Aerodynamic Force acting Perpendicular to the Relative Wind.

5

## Describe how factors in the Lift equation affect Lift Production.

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*Density(p), Velocity(V), Surface Area(S), Compressibility, Aspect Ratio(AR), Viscosity(u), AOA, Camber

L=qSCsubL=(1/2)pV(^2)SCsubL

*Shape of the Airfoil and AOA are Pilots Control for more Lift.

*Increase p or V or S will increase Lift.

**u, Compressibility, AR will be ignored for Lift.

6

## List the Factors affecting the Coefficient of Lift that a Pilot can Directly Control.

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Velocity, AOA, and The Shape of the Airfoil(limited)

**AOA is the most important factor in CofL

***Increase AOA until CLmax- the most effective AOA

7

## Define Drag.

### The Aerodynamic Force that is parallel to the relative wind, and acts in the same Direction.

8

##
Define Parasite Drag and its Components.

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(Dp) Drag not associated with the production of Lift.

Composed of

Form Drag- airflow separation from a surface and Low Press Wake

Friction Drag- Air Viscosity, air interacts with the surface of an object

Interference Drag- generated by the mixing of streamlines b/w Form and Friction.

9

##
Describe the measures that can reduce each of the components of Parasite Drag.

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Form- reduce by streamlining-reduce High Ps near Leading Edges

Friction- smoothing exposed surfaces-paint,clean,wax,polish.

Interference-minimize by proper Fairing and Filleting.

10

## State the effects of Upwash and Downwash on a Infinite Wing.

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Upwash exactly balances the Downwash resulting in no net change in Lift.

*exist any time an airfoil produces lift.

11

## State the effects of Upwash and Downwash on a Finite Wing.

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Upwash and Downwash are not equal, and some air flows up and around the wingtips producing more downwash. Thus Doubles due to Spanwise airflow resulting in Wingtip Vortices.

*

12

## Define Induced Drag.

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Portion of Total Drag associated with the production of Lift.

*the parallel component of Total Lift, since it acts in the same direction as drag and tends to retard forward motion.

13

##
State the cause of Induced Drag on a Finite Wing.

### Twice as much DW as UW near Wingtips, the Avg Relative Wind has a Downward slant compared to the free airstream Relative Wind = Total lift vector to now be inclined aft = Effective Lift will be less than Total Lift = Di.

14

##
Describe factors affecting Induced Drag. Given the Di Equation.

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Di = (kL(^2)) / (pV^2b^2) = (kW(^2)) / (pV^2b^2)

Weigh = Lift.

*Increase WT = Increase Di

**Inverse with Velocity and Direct with AOA.

15

## State when a plane will enter Ground Effect.

### Significantly reduces Di and Increases Effective Lift when the Airplane is Within 1 wingspan of the ground.

16

## State the effects of Ground Effect on Lift, Effective Lift and Induced Drag.

### Downwash at the Trailing Edge of the Wing is unable to flow Downward. Decreasing DW allows the Total Lift vector to rotate FWD, Increasing Effective lift and Decreasing Di.

17

## Describe the effects of AOA changes on Coefficient of Lift and Coefficient of Drag.

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Most important component and determines L/D ratio.

As AOA increase the CofL and CofD Increase up to CLmax.

18

## Explain the Lift to Drag Ratio, using L/D Ratio Equation.

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Is used to determine the efficiency of an airfoil. A high ratio indicates a more efficient airfoil.

*(CofL / CofD)

19

## Explain the importance of L/D MAX.

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The Maximum L/D ratio.

Located at the bottom of the total drag curve, any movement away from L/D max will increase Drag.

*High L/D ratio indicates a more efficient Airfoil.

20

## Define Total Drag.

### Dp and Di can be added together to create a Dt.

21

## Describe the effects of changes in Velocity on Total Drag.

### As Velocity Increases Dt Increases.

22

##
Define Thrust Components; Tr and Ta.

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Thrust Required: Thrust required to overcome Drag and expressed in LBS.

Thrust Available: amount of thrust the airplanes engines actually produce at a given Throttle Setting, Velocity, Density.

23

##
Define Power Components; Pr & Pa.

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Power Required: The amount of Power Required to produce Tr

Pr is the product of Tr x V.

Power Available: The amount of Power the the airplanes engines actually produce at a given Throttle Setting, Velocity, and Density.

24

##
Describe the effects of Throttle Setting, Velocity, and Density, on Ta & Pa.

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Ta: Max Eng. Output at FullThrottle(Pa), Density Decreases Ta Decreases, Prop-can only Accel air to Max V thus as Air Accel Ta Deacreases. Jet doesn’t bc of Ram-effect.

Pa: Pilot Reduces Throttle Pa decreases, Jet- V increases Pa Increases Linerarly, Prop-V Increases Pa initially increase until Ta Decreases, Decrease in Density Pa decreases.

25

## Define Thrust Horsepower and components; Shaft HP and Propeller Efficiency.

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Thrust Horsepower- (THP) The Output from the Propeller.

Shaft Horsepower- (SHP) The output from the engine.

Propeller efficiency (PE)- the ability of the Propeller to convert SHP & THP (PE=THP/SHP)

26

##
State the Maximum rated Shaft HP in the T6B.

### 1100SHP

27

##
Explain how PE affects Thrust HP.

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Due to Friction in the gearbox and drag on the Propeller, PE is never 100%.

2 ways to minimize loss of Thrust:Fixed Pitch or Variable Pitch Propellers.

28

##
Describe Pr in terms of Tr.

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Pr is the product of Tr and V.

Pr is the amount of Power Required to produce Thrust Required.

29

##
State the location of L/D MAX on the Tr and Pr curves.

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Tr: L/D Max AOA is the point of minimum Tr, bottom of the Curve.

PR: L/D Max AOA not at the bottom but slightly to the right of the curve.

*V and AOA for L/DMax are the same on Pr & Tr Curves.

30

##
Describe how Tr and Pr vary with Velocity.

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Flight at greater V require a reduction in AOA and Increase in Thrust to match the increased Parasite Drag.

Flight at lower V require an increase in AOA and Increase in Thrust to match the increased Induced Drag.

31

## Define Excess Thrust and Excess Power.

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Thrust Excess (Te): Ta is greater than Tr at a particular V.

Power Excess (Pe): Pa is greater than Pr at a particular V.

32

## Describe the effects of Excess Thrust and Excess Power.

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Positive Excess produce a climb, Acceleration

Negative or Deficit: result in a descent or a deceleration.

33

##
Describe the effects of change in WT on Thrust and Power components; Tr, Pr, Te, Pe.

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Increase in weight requires an increase in Tr and Pr

Pr is a function of Tr.

Tr and Pr curve shifts up and to the right - higher velocity = higher Dt.

34

##
Describe the effects of changes in Altitude on Thrust and Power components. Tr, Pr, Ta, Pa, Te, Pe.

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*Tr and Pr curve shift to the right- Altitude Increases(density decreases) V increases.

**Ta and Pa decrease at higher altitudes

**Te decrease with an increase in altitude due to decrease in Ta.

**Pe decrease with an increase in alt due to Pa decrease and Pr increase.

35

##
Describe the effects of changes in configuration on Thrust and Power Components; Tr, Pr, Te, Pe.

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Tr and Pr increase when Landing gear is lowered. Curve shift up.

**Ta and Pa are not affected

**Te and Pe decrease due to Tr and Pr increase.

36

## Describe the Aerodynamic effects of Raising or Lowering the Flaps.

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Lowering Flaps increase CofL, increase Dt and Tr.

*Tr curve shifts left.

Shift both Tr and Pr curves up and to the left - more thrust and power are required to maintain alt for a given V.

37

## Describe the aerodynamic effects of Raising and Lowering the Landing Gear.

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Ta and Pa not affected.

Te and Pe will decrease with Tr and Pr increasing.

38

## Explain the aerodynamic effects of each Primary Flight Control.

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Elevator - pitching moment around the lateral axis

Ailerons - rolling moment

Rudder - yawing moment.

39

## Describe how the Trim Tab System holds an Airplane in Trimmed Flight.

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Attached to the trailing edge of each control surface.

Trim tab move in opposite direction as the Control surface and creates a small force that exactly opposes the moment created by Control surface.

40

## Define Aerodynamic Balancing and Mass Balancing.

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Aerodynamic Balancing - balancing forces that act at the Aerodynamic center.

**keep control pressures associated with higher velocities within reasonable limits.

Mass Balancing - balancing the forces that act at the center of gravity and relocate them to the hinge line through weights in ctrl surfaces.

41

## State the methods for Aerodynamic and Mass Balancing employed on the T6B.

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Aerodynamic Balance - Shielded horns on the elevator and rudder.

Mass Balancing - weights in the overhang of ailerons.

42

## State the Characteristics of the 3 basic types of Control Systems.

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Conventional - direct control - push pul tubes, pulleys, cables and levers

Power-Boosted - mechanical linkages, hydraulic, pneumatic, electrical assists.

Full Power - fly by wire, no direct connection with Control surface, computer commands.

43

## State how Trim Tabs can be used to generate Artificial Feel on a Control Surface.

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Anti-Servo - move in the same direction, requiring more force to hold the control surface.

Neutral- maintains a constant angle to the control surface (elevator)

44