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Aero 1 > Lift Production And Drag 2-2 > Flashcards

Lift Production And Drag 2-2 Flashcards

1
Q

Explain the Aerodynamic relationship of 4 Forces in Equilibrium Flight.

A

Lift, Weight, Thrust, Drag.
Equilibrium flight when sum of all forces and moments are =Zero.
Lift acts against Weight and Drag acts against Thrust.

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2
Q

Describe how the primary Aerodynamic Forces affect each other.

A

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.
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3
Q

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

unanswered

A

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.

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4
Q

Define Lift.

A

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

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5
Q

Describe how factors in the Lift equation affect Lift Production.

A

*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.

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6
Q

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

A

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
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7
Q

Define Drag.

A

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

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8
Q

Define Parasite Drag and its Components.

A

(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.

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9
Q

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

A

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.

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10
Q

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

A

Upwash exactly balances the Downwash resulting in no net change in Lift.
*exist any time an airfoil produces lift.

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11
Q

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

A

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.
*

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12
Q

Define Induced Drag.

A

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.

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13
Q

State the cause of Induced Drag on a Finite Wing.

A

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.

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14
Q

Describe factors affecting Induced Drag. Given the Di Equation.

A

Di = (kL(^2)) / (pV^2b^2) = (kW(^2)) / (pV^2b^2)
Weigh = Lift.
*Increase WT = Increase Di
**Inverse with Velocity and Direct with AOA.

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15
Q

State when a plane will enter Ground Effect.

A

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

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16
Q

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

A

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.

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17
Q

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

A

Most important component and determines L/D ratio.

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

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18
Q

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

A

Is used to determine the efficiency of an airfoil. A high ratio indicates a more efficient airfoil.
*(CofL / CofD)

19
Q

Explain the importance of L/D MAX.

A

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
Q

Define Total Drag.

A

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

21
Q

Describe the effects of changes in Velocity on Total Drag.

A

As Velocity Increases Dt Increases.

22
Q

Define Thrust Components; Tr and Ta.

A

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
Q

Define Power Components; Pr & Pa.

A

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
Q

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

A

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
Q

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

A

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
Q

State the Maximum rated Shaft HP in the T6B.

A

1100SHP

27
Q

Explain how PE affects Thrust HP.

A

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
Q

Describe Pr in terms of Tr.

A

Pr is the product of Tr and V.

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

29
Q

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

A

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
Q

Describe how Tr and Pr vary with Velocity.

A

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
Q

Define Excess Thrust and Excess Power.

A 
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
Q

Describe the effects of Excess Thrust and Excess Power.

A

Positive Excess produce a climb, Acceleration

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

33
Q

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

A

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
Q

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

A
  • 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
Q

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

A

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
Q

Describe the Aerodynamic effects of Raising or Lowering the Flaps.

A

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
Q

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

A

Ta and Pa not affected.

Te and Pe will decrease with Tr and Pr increasing.

38
Q

Explain the aerodynamic effects of each Primary Flight Control.

A

Elevator - pitching moment around the lateral axis
Ailerons - rolling moment
Rudder - yawing moment.

39
Q

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

A

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
Q

Define Aerodynamic Balancing and Mass Balancing.

A

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
Q

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

A

Aerodynamic Balance - Shielded horns on the elevator and rudder.

Mass Balancing - weights in the overhang of ailerons.

42
Q

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

A

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
Q

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

A

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
Q

Describe the Purpose of Bobweights and Downsprings.

A

Provide pilot with Artificial Feel.
Downsprings - Increase the force required to pull the stick aft at Low airspeeds
Bobweights - increase the force required to pull the stick aft during maneuvering flight.

Aero 1 (3 decks)

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