Principles of Flight

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What is the unit of measurement of Pression?

Kg/m3

Kg*m/s

N/m2

What is the unit measurement of the density?

N/m2

kg/m3

kg*m/s

What is the definition of speed?

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The rate of change of distance.

The rate of change of distance in a specific direction.

What is the definition of Velocity?

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The rate of change in distance.

The rate of change in distance in a specific direction.

How to pass from Knots to m/s?

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m/s= 0,762(1852/3600) x knots

m/s= 0,5144(1852/3600) x knots

m/s= 0,5100(1852/3600) x knots

m/s= 0,314(1852/3600) x knots

How to know proximately the conversion from Knots to m/s

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Doubles

halve

How to pass from m/s to Knots?

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Knots= m/s x 1979 (3600/1852)

Knots= m/s x 1925 (3600/1852)

Knots= m/s x 1944 (3600/1852)

Knots= m/s x 1821 (3600/1852)

How to pass proximately from m/s to knots

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Halve

Double

How to pass from m/s to fpm (feet per minute)

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Fpm= m/s x 196,8 (60 x 3,28fpm)

Fpm= m/s x 194,8 (60 x 3,28fpm)

Fpm= m/s x 197,7 (60 x 3,28fpm)

Fpm= m/s x 198,8 (60 x 3,28fpm)

How to pass from fpm to m/s?

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m/s= fpm / 195,8 (60 x 3,28fpm)

m/s= fpm / 194,4 (60 x 3,28fpm)

m/s= fpm / 192,8 (60 x 3,28fpm)

m/s= fpm / 196,8 (60 x 3,28fpm)

How much is 1kg in libbre?

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202,5 lb

2,205 lb

2,502 lb

2,305 lb

To convert a mass in lb to kg…

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Kg= lb x 0,454

Kg= lb x 0,474

Kg= lb x 0,354

Kg= lb x 0,545

Kinetic energy?

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1/2mv2

1/2rhov2

Work=…

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Force x area

Power x time

Force x distance

Power/ time

Whats the definition of Power?

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Is the rate of doing energy

Is the rate of doing work.

Power=…?

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Power= Work/area = Force x distance/time = Force x speed

Power= Work/time = Force x distance/time = Force x speed

Power= Work/time = Force x pressure/time = Force x speed

Newton’s second law

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A body will remain at rest or in uniform motion unless acted upon by an external force.

To each and every action there is an equal and opposite reaction.

The acceleration of a body in a straight line is proportional to the applied force and inversely proportional to the mass of the body.

Newton’s first law

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To each and every action there is an equal and opposite reaction .

The acceleration of a body in a straight line is proportional to the applied force and inversely proportional to the mass of the body.

A body will remain at rest or in uniform motion unless acted upon by an external force.

Newton’s third law

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A body will remain at rest or in uniform motion unless acted upon by an external force.

to each and every action there is an equal and opposite reaction.

The acceleration of a body in a straight line is proportional to the applied force and inversely proportional to the mass of the body.

What’s the air density at mean sea level

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1,522 kg/m3

1,223 kg/m3

1,225 kg/m3

The greater the air density, the faster the

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mass flow

Pressure flow

Humidity flow

Air density= pressure/temperature

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Air density decreases if pressure decreases or temperature decreases.

Air density decreases if pressure decreases or temperature increases.

Air density decreases if pressure increase or temperature increases.

Choose the correct answer

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At constant temperature, the volume of a fixed amount of gas is directly proportional to its pressure.

At constant temperature, the volume of a fixed amount of gas is inversely proportional to its pressure.

Temperature=constant; Volume=Increases; Pressure=?

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Increases

decreases

Static pressure is equal in all directions?

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yes

Static pressure decrease with the increase of altitude?

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Yes

The more vigorous the vibrations, the greater…

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The humidity

the pressure

The temperature

When particles move more rapidly they each occupy more……

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Density

Pressure

Space

Particles moving rapidly occupy more space, which of the hot gas or cold gas have fewer particles of gas?

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hot gas

Cold gas

Which is less dense to the other?

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Cold gas

Hot gas

Air density is directly proportional or inversely proportional to the temperature?

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Inversely proportional

Directly proportional

Increasing the temperature, the density…?

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increase

Decrease

increasing the density, the temperature…?

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increase

decrease

273 kelvin =?

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-50 gradi

-273 gradi

0 gradi

viscosity is the………….of a fluid

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Unsticky

Stickiness

More viscosity, more…

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Pressure

Drag

Lift

Trust

Dry air=?

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O2N2

H2O

Humidity air=?

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H2O

O2N2

Weight of the molecular humidity air.

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H2O (2 of hydrogen and 16 of oxygen)= 18

O2N2 (32 of oxygen and 14 nitrogen)= min.28

Air density reduces with increasing humidity

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Yes

IAS relate to dynamic pressure or static pressure

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Dynamic pressure

Static pressure

1/2rhoV2. What’s V?

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Tas

Cas

Ias

Eas

The amount of dynamic pressure depends of:

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pressure static

Temperature

Humidity and speed of flow

Density of flow and its relative speed to the aircraft

If Air density halves, dynamic pressure

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Helves

Doubles

TAS increase, density pressure?

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Decrease

Increase

Greater te TAS, greater the energy of flow

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Yes

In this image, what is the pressure measured?

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Total pressure

Dynamic pressure

Static Pressure

How much are the errors of the IAS

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Which are the 3 errors of IAS

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Pressure error

Instrument error

Compressibility error

Temperature error

Relative error

The instrument suffers from small errors caused by limitations of the manufacturing process.

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Instrument error

Compressibility error

Pressure error

Error of measure the total pressure, in particularly the static pressure because of the static ports are oriented badly to airflow.

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pressure error

Instrument error

Compressibility error

At high speed the air entering the pitot tube becomes compressed which artificially raises its density and induces errors for measure Total pressure.

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compressibility error

Pressure error

Instrument error

CAS (calibrated Air speed) correcting:

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Pressure error

Compressibility error

Instrument error

EAS (Equivalent air speed) correcting:

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Pressure error

Instrument error

Compressibility error

EAS (Equivalent air speed) correcting:

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Pressure error

Instrument error

Compressibility error

In ISA conditions:

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EAS>TAS

EAS=TAS

EAS<TAS

At higher altitudes with less density:

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EAS/CAS/IAS<TAS

EAS/CAS/IAS>TAS

EAS/CAS/IAS=TAS

Coanda effect is a phenomenon in which a ……….-….…..attaches it self to a nearby……and remains attached though the surface……away from the initial flow direction.

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High speed-Pressure-surface-bends

High speed-Flow-surface-bends

Slow speed-flow-surface-bends

Slow pressure-pressure-surface-bends

Why Flow bends towards the upper surface of a wing?

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depletion of molecules

low pressure between flow and surface

Both answers are correct

Lines of flow which describe his direction.

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Stream tube

Streamlines

Pathlines

Volume of air bounded by streamlines is known as

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streamlines

Pathlines

Stream tube

Streamlines can cross each other

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Yes

Pathlines can cross each other

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Yes

Which lines we use in turbulent flow

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Streamlines

Pathlines

The act of converting streamline flow to turbulent flow requires a lot of……..

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Temperature

Pressure

Density

Energy

Over time, a vortex loses………to the surrounding air.

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Pressure

Energy

Density

Temperature

For flights at slower speeds we assume that the air is incompressible and without viscosity

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Yes

In the Equation of Continuity of Venturi the air density remains constant along all point of the tube.

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We don’t consider an ideal fluid

no.

Yes, because we consider an ideal fluid

Which theorem is This?

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Bernoulli’s Theorem

Venturi’s Theorem

Which theorem is this?

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Bernoulli’s theorem

Venturi’s theorem

The closer the streamlines are together, the faster the flow.

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Yes

Ps+q=Pt

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Equation of continuity

Bernoulli’ theorem

An unbalanced force is produced by the difference of:

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Dynamic pressure above and below the body.

Static pressure above and below the body.

Dynamic pressure only above.

Static pressure only below.

An unbalanced force is produced when the object:

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Is curved

Has a sharp trailing edge

Has a curved leading edge

Is set at a relatively low angle to the airflow

The flow is faster, the…

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static pressure is lower

Static pressure is higher

The flow is slower, the…

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static pressure is lower

Static pressure is higher

Leading edge radius of high speed airfoil is much

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Smaller

large

imaginary straight line between the centre of the leading edge and the trailing edge

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chord line

Chord

The distance from leading edge to trailing edge

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Chord line

Chord

Angle of attack is the angle between:

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Chord and direction of the airflow

Chord line and direction of the airflow

Leading edge radius and RAF

RAF=

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Relative air flow

Radius angle flow

Range attack flow

Mean camber line is an:

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imaginary line half-way equidistant between the upper and lower surface of the aerofoil.

imaginary line half-way not-equidistant between the upper and lower surface of the aerofoil.

Distance between camber line and chord line:

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Chord

Camber

Mean camber line

Cambered air flow:

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Symmetric aerofoil

Asymmetric aerofoil

Symmetrical aerofoil:

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Mean camber line coincide with the chord line

Mean camber line is upper the chord line

Mean camber line is below the chord line

Symmetrical aerofoil:

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Camber<0

Camber=0

camber>0

The fin and rudder often use symmetrical aerofoils

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Yes

Positively cambered aerofoil:

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Mean camber line is above the chord line

Mean camber line is below the chord line

Negatively cambered aerofoil:

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Mean camber line is above the chord line

Mean camber line is below the chord line

Choose the correct answer.

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Positive camber

Negative camber

Symmetrical camber

Biconvex

Choose the correct answer.

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Symmetrical camber

Negative camber

Positive camber

Biconvex

Choose the correct answer.

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Negative camber

Symmetrical camber

Positive camber

Biconvex

Choose the correct answer.

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Symmetrical camber

Biconvex camber

Negative camber

Positive camber

The thickness-chord ratio

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Aerofoil maximum thickness to the length of its chord

Aerofoil minimum thickness to the length of its chord

T/C greater for low speed wing

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Yes

Free stream flow has free stream velocity and free stream pressure

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Yes

The dividing line between the upper and lower flows is known as the stagnation line.

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Yes

Upward flow of air before leading edge

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Upflow

Upwash

Downward flow of air which leave trailing edge

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Downflow

downwash

100

the differences in surface pressure around the aerofoil create unbalanced forces at every point.

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yes

101

the net unbalanced force is know as total reaction

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true

false

102

total reaction take into account the pressure differentials between the upper and lower surface, but also the pressure differentials between the front and rear of the aerofoil.

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yes

103

the total reaction is inclined slightly rearwards because of the pressure differentials between the front and rear of the aerofoil.

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true

false

104

The point of origin of total reaction is called:

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centre of pression

centre of gravity

105

totale reaction can be divided into 2 components, lift and drag

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true

false

106

lift is perpendicular to the free stream air

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true

false

107

Is this the total reaction?

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Yes

108

air has viscosity, its flow is affected by:

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Density

Friction

109

there are 2 types of drag: ...................drag and ...................drag

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skin friction drag

form drag

parallel drag

total drag

110

a very small proportion of the airflow is brought to a complete standstill near the leading edge at the stagnation point.

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true

false

111

flow faster, static pressure reduce and dynamic pressure increase

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true

false

112

behind a body the flow is slower and the static pressure increase.

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yes

yes, only with ideal fluid

113

at stagnation point dynamic pressure is converted into static pressure

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true

false

114

there are 2 stagnation points, ahed landing edge and rear trailing edge

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true

false

115

on the rear statgnation point pressure dynamic is converted into static pressure when upper flow and downerflow meeting

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true

false

116

the stagnation point is also called stagnation pressure

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yes

117

In an ideal fluid a body cant produce resistence, than cannot produces aerodynamic forces.

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true

false

118

The phenomenon where an ideal fluid a body cant produce resistence, than cannot produces aerodynamic forces is called:

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bernoully's phenomenon

Venturi's phenomenon

paradox of d'alembert

119

first layer above the aerofoil which is the cause of 2 types of drag

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stronger layer

lower layer

boundary layer

general layer

120

skin friction drag is produced by the effect of viscosity on the pressure distribution aroud the object.

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true

false

121

skin friction drag is caused directly from friction within the boundary layer.

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true

false

122

form drag is produced by the effect of viscosity on the pressure distribution around the object.

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true

false

123

because of viscosity there is a turbolent flow behind the body

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true

false

124

the region of lowest static pressure is on the upper surface of the aerofoil within the first 1/3rd of the wing chord.

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true

false

125

the point of maximum thickness of an aerofoil usually occurs:

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at the leading edge

about half way along the chord lenght

in the first 1/3 of the chord lenght

closer to the trailing edge than the leading edge

126

the greater the speed of the flow, energy:

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decrease

remain costant

127

if the flow increase velocity, total reaction:

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Halves

Doubles

remain costant

128

if the airspeed doubles, the centre of pressure remains unchanged.

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true

false

129

because the aerofoil is symmetrical, the air accelerates equally above and below it giving an equal pressure distribution and thus no lift.

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true

false

130

symmetrical aerofoil creates drag and no lift:

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true because alpha is <0

true because alpha is >0

True because alpha is =0

false.

131

increase angle of attack, increase total reaction

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true

false

132

increase angle of attack, increase total reaction, the centre of pressure:

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change position at about one quarter of the distance along the chord

unchange position at about one quarter of the distance along the chord

133

increasing the aerofoil's camber, increase velocity of flow upper the surface and decrease below the surface, this means that a camberd aerofoil produces differential pressure and lift, even at 0 angle of attack

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true

false

134

stagnation point is slightly lower for the:

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symmetrical aerofoil

cambered aerofoil

135

lowest pressure is also called :

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Stagnation pressure

Zetapressure

suction peak

136

because of suction peak (forms further forwards than before) has implications for the position of centre of pressure.

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true

false

137

the effect of a small positive angle of attack on a cambered aerofoil increase total reaction and move the CP forwards.

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true

false

138

The aerodynamic force is the product of the pressure acting over the aerofoil’s surface area.

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True

False

139

Aerodynamic force depends mainly on dynamic pressure, the surface area of the aerofoil and the aerodynamic force coefficient.

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true

False

140

Correctly equation:

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F= q S CF

F=q V2

F=1/2qv2

141

CF= qS/F?

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true

false

142

CF=F/qS

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true

false

143

surface pressure?

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F/A (area)

A/F

q/A

144

CF=surface pressure/dynamic pressure

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true

false

145

increasing angle of attack, increase the flow over the upper surface and decrease the static pressure

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true

false

146

lift= 1/2 q V2 S CL

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true

false

147

3 main factor affect lift:

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Angle of attack

Thickness

Camber

Chord line

148

Which type of aerofoil is?

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Cambered

Symmetrical

149

at angles of attack greater than the stalling angle, the wing stall.

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true

False

150

a negatively cambered aerofoil produces a negative value of CL at 0 alpha.

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true

false

151

IAS squared is proportional to dynamic pressure

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true

false

152

L= IAS squared S CL

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correct

wrong

153

in a power aircraft the energy is supplied by the engine

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true

false

154

aeroplane transmits momentum to the air molecules.

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True

False

155

the surface roughness, traps the molecules closest to the surface and carries them at the same speed as the aircraft.

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true

false

156

Form drag is caused by asymmetry in the areas of high pressure in front of and behind the aerofoil.

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true

false

157

the static pressure to the rear is lower than the static pressure around the front stagnation point.

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true

false

158

skin friction drag occur in boundary layer.

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true

false

159

the 2 types of drag are known as :

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collectively drag

profile drag

160

shear force is produced between 2 layers.

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true

false

161

greater the shear force, greater the

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density

thickness

viscosity

162

the boundary layer is defined as the area extending from the aircraft's surface out to the point where the speed of the airflow is 99% of the free-stream flow

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true

false

163

the boundary layer consist in laminar and turbolent

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true

false

164

a turbulent boundary layer is:

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thick, draggy and high energy

thin, slippery and low energy

165

a laminar boundary layer is :

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thin, slippery and low energy

thick, draggy, and high energy

166

laminar boundary layer is deep

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a few millimetres

a few centimeters

167

turbolent boundary layer is deep

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a few millimeters

a fewn centimeters

168

the transition region/point is the point where the boundary layer changes from laminar to turbulent

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true

false

169

laminar flow occur when

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viscous forces are dominant

high inertial forces are dominant

170

turbulent flow occur when

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viscous forces are dominant

high inertial forces are dominant

171

the reynolds number describes the ratio of inertial forces to viscous forces.

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true

false

172

when the reynolds number is below 500.00 :

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indicate a laminar flow with viscous forces

indicate a turbulent flow tith inertial forces

173

when the reynolds number is grater than 10.000.000 :

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indicate a laminar flow with viscous forces

indicate a turbulent flow with inertial forces

174

a rougher surface creates more skin friction drag and reduce the energy of the boundary layer, produce change from laminar to turbulent flow.

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true

false

175

dirty or ice wing surface causes a greater skin friction drag.

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true

false

176

transition point is always before the maximum thickness

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true

false

177

in modern aerofoil, the point of maximum thickness is

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between 50-60% of the chord line

at maximum 30% of the chord line

178

in a low-speed aerofoil, the point of maximum thickness is

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between 50-60% of the chord line

at maximum the 30% of the chord line

179

the separation point is the point at which the boundary layer separates from the upper surface of the aerofoil.

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true

false

180

after the transition point, friction forces slow the flow speed of the turbulent boundary layer. The layers near the aerofoil loose the kinetic energy and the upper flow with greater kinetic energy overcome the layers with less kinetic energy and tush separate low layers from the surface.

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true

false

181

turbulent layers resists separation better than a laminar layer because it has more kinetic energy.

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true

false

182

the effect of separation is a reduction in lift and an increase of drag

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true

false

183

the separation point moves forward if the angle of attack increase.

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true

false

184

flow reversal occur behind the separation point

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true

false

185

the adverse pressure gradient opposes the relative air flow

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true

false

186

after the peak suction point, the static pressure along the chord increases.

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true

false

187

the air flow decrease because of the adverse pressure gradient.

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true

false

188

if the angle of attack increase the adverse gradient becomes:

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stronger

weak

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