Theory of Flight Flashcards by EJ *

What is momentum?

Mass x Velocity

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What is Newton’s 1st Law?

A body remains in a state of rest or in uniform motion in a straight line unless acted upon by an external force. (Inertia)

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What is Newton’s 2nd Law?

The rate of change of momentum is proportional to the applied force and the change in momentum takes place in the direction of the applied force. (Results in F=ma)

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What is Newton’s 3rd Law?

Every Action has an equal and opposite Reaction. (Action/Reaction)

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A gas in steady motion has what 4 types of energy?

Potential Energy Heat Energy (Pressure Energy) Kinetic Energy

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Total pressure is the sum of what two types of pressure?

Static pressure + Dynamic pressure

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What is the equation for dynamic pressure?

1/2 ρ V²

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What are the 4 forces that act on an aircraft in flight?

Lift, Drag, THrust, Weight

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Label this diagram of an aerofoil.

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What is the curvature of an aerofoil?

Camber

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What is the straight line distance between the leading and trailing edges?

Chord.

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What is the angle at which the aerofoil is attached to the fuselage, defined as the angle between the chord line and the longitudinal fuselage datum?

Angle of incidence

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What is the angle between the chord line and the relative airflow / freestream flow?

Angle of attack

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What is the maximum lateral dimension of a wing?

Wingspan

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what is the planform area of a wing?

WIng Area

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What is the ratio between the wing span and the mean chord?

Aspect Ratio

What is the change of the chord of the wing from root to tip?

Taper

What is the layer of airflow close to the aerofoil surface, where the velocity of flow is reduced from the free stream flow due to viscosity?

The Boundary Layer

What is the point on an aerofoil where the boundary layer becomes turbulent?

Transition Point

What are the two types of flow in a boundary layer? Briefly describe them.

Laminar - the flow is smooth.

Turbulent - the flow is rough and unpredictable.

What is the point on an aerofoil where the resultant vector of lift and drag acts?

Centre of pressure

Label this diagram of an aerofoil.

What are the 7 factors that the generation of lift is dependant on?

Air Density ρ

Velocity V

Wing Area S

Coefficient of Lift

Angle of attack

Wing Shape

Wing Surface Condition

What effect does downwash have on the angle of attack?

Downwash causes an effective decrease in the angle of attack

Name the two types of drag on an aerofoil.

Zero lift drag (ZLD) Lift Dependant Drag (LDD)

What are the 3 components of zero lift drag?

Surface friction drag Form drag Interference drag

What type of drag is the following describing? Airflow spills from the wingtip and trailing edge in a twisting motion to form trailing vortices. At the wing tip, the vortices form into a concentrated vortex These vortices intensify under high lift conditions

Induced drag (Due to spanwise flow)

Label the drag curve.

At what angle of attack does the maximum coefficient of lift occur?

16°

At what angle of attack does the minimum drag occur?

2°

At what angle of attack is the Lift to drag ratio optimized?

4°

What does V_IMD represent?

Best lift to drag ratio. (Indicated airspeed, minimum drag)

What does 1.32 x V_IMD achieve?

Best range. (Max speed/drag ratio)

Label the axes and planes on this aircraft diagram.

What are the primary response to each of the following controls? Elevator Ailerons Rudder

Elevators - Pitch Ailerons - Roll Rudder - Yaw

What are the **secondary** effects of each of the following? Elevator Ailerons Rudder

Elevator - height/speed Ailerons - Yaw Rudder - Roll

What device on a wing has the following effects? Increased lift due to; increased camber, change of chord, increase in AOA, increased S Improved forward vision as a result of a lower nose attitude. Increased drag, decreased Lift/Drag ratio and a lower critical angle.

Flaps