Principles of Flight Flashcards
The quantity of matter a body possesses
Mass
The rate of change of velocity
Acceleration
The rate of change of position of a body in a specified direction
Velocity
Energy cannot be _____ only _____
Destroyed
Transferred
1/2MV² =
K.E.
Force x Distance =
Energy
Power = Energy/_____
Time
Power = ____ x Distance / Time
Force
Energy = ____ x ____
Force
Distance
Force x Speed =
Power
Newtons 1st Law:
An object will continue at a constant velocity unless acted upon by an unbalanced force
Newtons 2nd Law
The rate of change of momentum is equal to the force applied. (F =MA)
Newtons 3rd Law
Every action has an equal and opposite reaction
When air temperature increases, the _____ _____ it is.
Less Dense
The more _____ the air, the less dense it is
Humid
The _____ the altitude, the less dense it is
Higher
Air density (ρ) = ____ / Temperature (T)
Pressure (P)
°C to Kelvin =
+273°C
Sea level temperature
15°C
Sea level pressure
1013.25HPa
Sea level Density
1.225kg/m³
Lapse rate
1.98°C per 1,000ft up to 11km (36,089ft)
Temperature above 11km
-56.5°C
IAS
Indicated Airspeed
CAS
Calibrated Airspeed
EAS
Equivalent Airspeed
TAS
True Airspeed
Total pressure (Pt) = _____ Pressure + _____ Pressure
Dynamic (q)
Static (Ps)
Dynamic Pressure ~ _____
Indicated Airspeed
q or IAS = 1/2ρV² =
q or IAS = 1/2ρTAS²
If ρ _____, __ must increase
Decreases
V²
1013.25HPa
Sea level Pressure
1.225kg/m³
Sea level Density
___ –> Instrument/_____ error –> CAS –> _____ –> EAS –> Density –> ___
IAS –> Instrument/Pressure error –> CAS –> Compressible –> EAS –> Density –> TAS
IAS –> _____/Pressure error –> ___ –> Compressible –> ___ –> _____ –> TAS
IAS –> Instrument/Pressure error –> CAS –> Compressible –> EAS –> Density –> TAS
IAS = TAS √(_____/ρ sea level)
ρ current alt.
3 types of flow:
Streamline
Turbulent
Vortex
The faster the _____. the _____ the stream tube
Molecules
Thinner
Streamlines are
Lamina flow (smooth)
Vortex flows require
lots of energy
Streamline flows have the least _____ and _____
Energy
Drag
Turbulent flow path lines can _____ and _____
Touch
Cross
Perfect fluid basic assumptions
They are In-compressible
They have no Viscosity
You should factor in air compression at speeds above _____
350 knots
Mass can neither be _____ or _____
destroyed
AVρ = _____
Mass flow = constant
The rate of change of momentum is equal to the force applied. (F =MA)
Newtons 2nd Law
Acceleration =
The rate of change of velocity
An object will continue at a constant velocity unless acted upon by an unbalanced force
Newtons 1st Law
Velocity =
The rate of change of position of a body in a specified direction
Mass =
The quantity of matter a body possesses.
Every action has an equal and opposite reaction
Newtons 3rd Law
1nm = __m
1852m
1m = __ft
3.28ft
1nm = __ft
6076ft
1 inch = __cm
2.54
1kg = __Ibs
2.2Ibs
m/s = ___ x knots
0.5144 (approx 0.5)
knots = ___ x m/s
1.944 (approx 2)
The drag effects in 2D are….
Form Drag, and Skin Friction Drag
Interference Drag is caused by
Flow hitting a junction and having to change direction
Parasite drag is made up of
Form, Skin Friction, and Interference Drags
Total Drag is made of Parasite Drag, and….
Induced Drag
Parasite drag is ________ to V^2
Proportional
Induced Drag is _________ to V^2
Inversely proportional
To reduce interference drag, we can create less hard junctions using
Fillets, or Fairings.
Skin Friction Drag is affected by…. (4 things)
Speed, Surface Area, Boundary Layer conditions, Type of Surface.
Parasite Drag Equation
D = 0.5 Rho V^2 S Cdp
A clean air craft will create _________ Parasite Drag
Less
A heavy aircraft will create __________ Induced Drad
More
Induced Drag equations are…..
ID is inversely proportional to aspect ratio
ID is inversely proportional to IAS^2
ID = 0.5 Rho V^2 S Cpi
Coefficient of Induced drag is proportional to
(Coefficient of lift)^2
Coefficient of Induced drag is Inversely proportional to
Aspect Ratio
As speed is reduced by a half, Cdi increases by a factor of
16
Wing tip modifications are used to….
Reduce induced drag, by reducing wing tip vorticies.
3 main types of wing tip modification
Winglets, Wing tip Tanks, Tapered Tips
Vmd is….
Velocity of Minimum Drag
At Vmd….
parasite drag = induced drag
Drag _____ to Vmd, then…
Decreases, increases in a non linear fashion
On the backside of the speed curve….
V
Above the Vmd on the speed curve….
we have Speed stability
At the bottom of the speed curve, near to Vmd….
we have Speed Neutral. Little changes in speed will not change drag by much.
How does the total drag curve change with IAS?
It does not! Ruler bend is ruler bend, is ruler bend…. whatever that means.
When plotting Total Drag against TAS, increasing altitude….
shifts the Total drag curve to the right.
When plotting Total Drag against TAS, increasing weight….
shifts the total drag curve to the right, and up. (a sort of pivot effect)
When plotting Total Drag against TAS, using flaps etc….
pivots the total drag graph anticlockwise from the end of the nike tick shape
Increasing altitude ________ the TAS of Vmd
Increases
Increasing weight, ________ the TAS of Vmd
Increases
Flaps down, Vmd…..
down.
Cd= (2 components)
Cdp + Cdi, or Cdi +k(Cl)^2
As L=q S Cl, and D=q S Cd…
L/D = Cl/Cd
By plotting Cd against Cl, we create the drag polar graph. the gradient of this graph will give us
Cd/Cl, or L/D
Maximum L/D is the _________ Lift
Greatest
Vmd is at ________ AoA
4 degrees
Min D/L is the __________ lift
Maximum lift
Lift to drag ratio of a training aircraft
11:1
Lift to drag ratio of a modern air transport plane)
20:1
Straight rectangular wings stall at the______ first.
Root
Swept wings stall at the _______ first
Wingtip
Stalling at the wingroot first is advantages because….
it creates a natural buffer in the tail, warning or an imminent full wing stall.
If a swept wing stalls…. (3 things)
Uneven stall could cause wingdrop
CP moves forward and inward
We get a nose-up moment.
A deep stall mainly affects
T-tail designed planes
A deep stall means that….
the horizontal stabiliser becomes completely immersed in turbulent wake from the stalled wing, that it loses all effectiveness. This is very bad…. and will probably result in a large bang as you hit the ground.
To reduce wing tip stalling tendencies in swept wings we need to….
reduce the lateral movement of air over the wing.
To reduce the wing tip stalling tendencies of a swept wing, we can install (3 things)….
Vortilon, a Wing Fence, or a Saw Tooth design.
A Low-speed cross-sectional wing will have ________ Cl, _________ Clmax and _________ AoA
Greater, Greater, Higher
A high-speed Cross-sectional wing will have ________ Cl, _________ Clmax, and __________AoA
Lower, Lower, smaller
A Stall Strip…..
Artificially increases the sharpness of a wing, to instigate an early root stall
Flaps are a……
Camber changing device
Slats …..
Re-energise the boundary layer.
Draw the graph of showing how Trailing Edge flaps, Leading edge flaps, and slats/slots affect the Clmax and AoA.
I’m not paying to go pro to add images, so check p327 of the text, or your notes!
Using Ailerons close to critical AoA can cause
Adverse Camber Roll, due to stalling of the wingtip.
Increasing mass will _________ Stalling Speed
Increase
Putting flaps down will _________ stalling speed
Decrease
Putting landing gear down will ________ stalling speed
Increase
With Power On, stalling speed is…
Slower
With Power off, stalling speed is…
Higher
Swept wing planes have a _______ Stalling speed
Greater
A plane with a further forward CoG will have a _______ stalling speed
Greater,
As we increase altitude, what happens to stalling speed?
It remains the same
At high altitude, with high TAS above 300kts, what happens to IAS stalling speed?
Stalling speed will increase.
Contamination causes the stalling speed to
Increase
Manoeuvers cause the stalling speed to….
Increase
The load factor in a turn is
1/cos (Phi), where phi is the angle of bank.
Vs= Stall Speed at 1g x
Sqrt(Load Factor)
Flaps are camber chaning devices. ToF?
True
Slats are camber chaning devices. ToF?
False
Increasing camber by using trailing edge flaps __________ Cl, ________Clmax, and ________Critical AoA
Increases, Increases, Decreases
Slots allow….
high pressure air to travel through the wing, re-energising the boundary layer, delaying the separation point and delaying the stalling AoA.
Using Ailerons close to your critical AoA can cause….
the wing to stall, resulting in Adverse Camber roll
CS23 requires the Vs to be multiplied by what, to give Vs1 and Vs0
1.2 for Vs1, 1.3 for Vs0
CS25 requires the Vs to be multiplied by what, to give Vs1 and Vs0
1.13 for Vsr1, 1.23 for Vsr0
For Autorotation to occur….
Both wings must be stalled
To recover a stall, we must….
Increase power…………just kidding, it’s reduce AoA
Easa regulations state aircraft must have an ______ stall warning
Audio
The Margin for a stall warning system is….
5kts or 5% above a stall, whichever is greater.
Aeorodynamic stall warnings
occur naturally for aerodynamic reasons (buffet)
Artificial Sall warning systems are,,,
Electro-mechanical sensors that detect a stall
At the stall we can expect….. (4 things)
Cl collapse and descent, increased buffet, Nose up or nose down moment, depending on wing shape, wing drop.
Stall prevention devices engage at….
2kts, or 2% above stall speed
A stick shaker is a stall _______ device
warning
A stick pusher is a stall _________ device.
Prevention
A forward sweep wing would be better in a stall, however…..
required to be stronger, and therefore hevier.
A plane with elevator stabilisers ahead of the wing is called….
Canard
The advantage of elevators in front of the wing, is that….
The wing has to produce less lift.
A flapper switch uses what to recognise when you are reaching your stalling AoA?
The stagnation point on the leading edge
AoA Vanes….
Attach to the side of the fuselage and electronically detect AoA to effective airflow.
AoA vanes are more accurately described as….
“Air Direction Detectors”
AoA Probes….
Use two slots to identify differing air pressures, thus calculating AoA
Rotating probes…..
are Null Seaking, and rotate to balance the air pressure in two tubes, detecting AoA
Pitch indicators on deisplays are often called….
eyebrows!
Vsw is,,,,
Velocity Stall Warning
The R in Vsr is there because…
it is a calculated speed
The stalling angle on a swept wing plane is….
less defined
With flaps down, the CP
Moves back
With a high wing plane, when extending flaps, there is a transitional…
Nose up rotation.
Usually, lowering flaps will cause a ______ ______ Rotation
nose down rotation
Lowering flaps _______ Downwash
Increases
A split flap will do what to Cl and critical AoA
Greater Clmax and AoA than plain flap, but still small AoA than a clean wing. Cl will remain the same for same AoA for a normal flap.
A leading edge flap gives…..
More camber
A Krueger Flap is found on what make of aircraft?
Boeing
A Krueger Flap reduces the…..
Leading Edge Radius, and therefore induces seperation.
A Kreuger flap increases the
Camber
A leading edge flap that creates a Slot is called a….
Slat.
A fowler flap….
Increase surface area and camber.
A Fowler flap moves
Aft first, and then down,
A Fowler flap will most likely require a
slot, to reenergise the boundary layer.
Slots and slats increase
Critical AoA
Slats that are fixed……
do not exist. they must move to be a leading edge flap, and therefore a slat.
With Flaps down, we have ______wingtip vorticies
Smaller.
At landing, flaps will _______ our decent angle.
Steepen
Wing tip vortices _____ when flaps are lowered due to less _____.
Decrease
Downwash
Vortex generators produce _____ _____ which _____ the boundary layer. These are placed in front of the _____.
Small vortexes
Increase
Ailerons
Usually, the first __% of flap deflection provides more than half the total increase in Cl
50%
The second 50% provides more than half of all _____
Drag
Complete flap failure requires:
Faster approach at a higher AoA
Longer landing run
Reduced margin above the stall requirement
Flap protection system use an _____ to prevent flaps from being lowered until the speed falls below the _____ _____ _____
Interlock
Flap extension speed
What do configuration warning systems do?
Alert the crew to an incorrect flap setting for the particular flight phase
What do Flap asymmetry sensors do?
Stop flap operation if they detect that flap is lowering
asymmetrically
The Ram Effect is
The cushioning effect when the pressure below the wing rises because the volume between the ground and the lower surface of the wing reduces, compressing the air flowing underneath.
In the ground effect vortices become _____
Compressed
In ground effect, the EAF is _____, resulting in a reduced _____ _____ and an increased _____ _____. this means the stalling angle is _____.
Shallower
Induced angle
Effective angle
Reduced
The closer to the ground you are, the _____ the effect.
Greater
In ground effect, lift is _____, known as _____. and the induced rage is _____.
Increased
Ballooning
Reduced.
Entering the ground effect results in a nose _____ moment and leaving it results in a nose _____ moment. This is due to the decreased/increased _____.
Down
Up
Downwash
Entering the ground effect will make the IAS _____ _____
Under read
The ground effect come into effect _______ from the ground, but is not noticeble until _______ from the ground.
1 wingspan
1/2 wingspan
Flaps are
Camber changing devices
Hinge moment = __________ x __________
Hinge moment = force felt x distance from the hinge
An inset hinge is where…
The hinge on the control surface is moved back to reduce the hinge moment.
A horn balance is…
an area of control surface in front of the hinge which produces an opposite hinge moment.
An internal balance is…
a flexible diaphragm between the trailing edge and the control surface which creates a a force on the control surface to help move it due to pressure difference above and below the wing.
A balance tab is…
A tab at the rear of the aircraft that moves in the opposite direction of the control surface to aid it’s movement.
An anti-balance tab is…
The opposite of a balance tab for when the controls are too easy to move.
It is not an aid.
A servo tab is…
Similar to a balance tab, but the control column moves the tab which then as a result moves the control surface.
This is only good a high speed
A spring tab is…
Where due to a springs force, if at high speed, the control column will move the tab, and if at low speed, it will move the control surface.
Mass balancing is…
where mass is added ahead of the hinge line to prevent flutter.
It is not an aerodynamic balance.
Power-assisted controls:
The control column is directly attached to the control surfaces, however hydraulic forces provide most of the source.
Fully-powered controls:
The control column is not directly connected to the control surface. It requires an artificial feel system (Q-feel system).
The AoA _____ on a down-going wing and _____ on an up-going wing.
Increases
Reduces
A tailplane pitch is normally set to a _____ incidence due to the forward ___
Negative
CG
What type of tailplane is more effective?
The T-tail
When the rudder is deflected, the aircraft will _____ and if held it will _____.
Yaw
Sideslip
A rudder travel limiter…
Prevents the rudder being moved to far and breaking off at high speeds.
Adverse aileron yaw
There is less drag on the downward wing, and more on the upward wing.
Differential Ailerons
The angle of the aileron on the down-going wing is greater than that of the up-going wing
Firse Ailerons
The leading edge of the aileron is asymmetrically shaped. when facing upwards it increases the form drag.
On large aircraft, at high speeds, the _____ ailerons are locked and the _____ ailerons are used only. _____ _____ are used to aid roll control.
Outbound
Inbound
Flight spoilers
Advantages of spoilers:
Don’t suffer from flutter
Leave trailing edge free for flaps
Cause no twisting moment
Flaperons
The inboard aileron aiding the function of the flaps.
Control coupling
Rudder is used when a roll command is made aiding against adverse aileron yaw
Spoilers
Disturb the airflow and reduce the Clmax
Speed breaks can be used to
Reduce airspeed rapidly
Increase angle of descent
Increase rate of descent
Control the airspeed in a descent
Aileron droop
Ailerons can be drooped slightly for take off to compensate for the loss of potential flap area, increasing the camber and lift
Rudder primary and secondary effect
Yaw
Roll
Aileron primary and secondary effect
Roll
Sideslip the yaw
Equilibrium
When all 4 forces acting on an aircraft are equal and opposite.
Trimmable horizontal stabiliser (THS)
controlled by an electric screw jack which drives the staboliser to a positive or negative AOI.
THS are used on modern jet aircraft because:
They are aerodynamically effective
Doesn’t reduce effective range of the elevator
Have more force than the elevator
It is important to set the THS to the correct incidence before take off because…
An angle to positive can reduce the rate of rotation
An angle to negative can increase risk of tail strike
Load factor = _____/_____
Load factor = lift/weight
Thrust acts in the opposite direction to….
Relative air flow
Increasing thrust on a conventional airliner results in a _______ pitching moment
Nose-up
If wind = 0, the flight path angle and the AoA is _____
The same
Angle between the horizontal axis and the aircraft’s longitudinal axis.
Pitch angle
Angle between the flight path angle and the longitudinal axis
AoA
Angle between the horizontal and the flight path
Flight path angle (γ)
The more excess thrust…
The greater the climb angle
Best angle of climb
The steepest climb angle
Best rate of climb
Climbing as quick as possible
Excess thrust = _____ x _____
weight x sinγ
Lift = _____ x _____
weight x cosγ
Climb angle equation
Sinγ = T - D/W
The more weight, the _____ the climb angle
Shallower
In a steady climb, Weight is _____ than lift. Thrust is _____ than drag
Greater
Greater
For jet aircraft, Vx is the same as _____ at an AoA of _____.
Vmd
4°
For Jet aircraft at altitude, Vx ___________
Stays the same
For prop aircraft, Vx is __________
Close to stall speed
For prop aircraft, Vmp is ___ Vmd, where the AoA is _____
0.76
>4°
The flight path _____ with altitude
Reduces
% gradient =
(T - D / W) x 100
Shallow glide angles are achived with a _____ configuration
Clean
Descending at Vmp is a _____ angle, but descends _____
Steeper
Slower
Descending at Vmd is a _____ angle, but a _____ descent
Shallower
Faster
_____ does not effect the glide angle
Weight
A tailwind will _____ the glide path, and a headwind will ______ it.
Increase
Decrease
The force that opposes centrifugal force is ________
Centripetal force
The horizontal component of lift supports the _______ and the vertical component supports the _____.
Centrifugal force
Weight
What 2 things effect the radius of a turn?
Speed
Weight
Equation for CPF
CPF = M x V²/ r
Equation for radius of a turn
r = V² / g x TanΦ
Equation for the bank angle
CosΦ = W/L
LF = 1/CosΦ
Rate 1 turn:
3° per second, 180° a minute
Rate if turn =
(TAS / Radius) x 60
If double the airspeed, radious will _____ and the rate of turn will _____.
x4
1/2
Turn equations only use _____
S.i. units
Turn and slip indicator
Indicates rate of turn and the centripetal force Vs centrifugal force.
Maximum turning performance is determined by:
Max. lifting capability
Structural strength
Thrust
What properties does and ideal liquid have?
Incompressibility, Zero Viscosity
In an ideal fluid, the flow pattern that strikes an object and then doesn’t flow around it happens at the ______ ______
Stagnation Point
Viscosity in a flow pattern creates ______ behind the object
Wake
Unbalanced force created by an object in viscosity is called ______ ______
Form Drag
Lift to Drag Ratio for Training Aircraft
10:1 - 12:1
Lift to Drag Ratio for Long Haul Jets
18:1 - 20:1
Lift to Drag Ratios for Gliders
Above 25:1
The front of an Aerofoil is called the _____ _______
Leading Edge
The rear of an Aerofoil is called the _______ ______
Trailing Edge
The horizontal distance between the Leading and Trailing edges is the….
Chord
The shortest distance between the Leading Edge and the Trailing Edge is the…..
Chord Line
The leading edge radius is…..
The radius of a circle that would create the leading edge.
The Thickness of a wing, is the….
Wing thickness, at its thickest point
The Camber Line is the….
Imaginary line that bisects the Aerofoil
The Camber is….
The distance between the amber line and the surface of the wing.
Angle of Attack is…..
The angle between the Chord Line, and the Relative Airflow.
The 4 types of Aerofoil are…
Positive Camber
Negative Camber
Symmetrical
Biconvex
The two types of Aerofoils we work with in POF are…
Positive Camber
Symmetrical
The Thickness to Chord ratio is also called the ____ of the Aerofoil
Fineness
As AoA increases, the Stagnation point…..
Moves further down the leading edge
As AoA decreases, that Stagnation point……
Moves further up the leading edge
The ________ ______ is the point of greatest static pressure reduction
Suction Peak
Aerodynamic Total Reaction is made up of which two forces?
Lift and Drag
A sharp trailing edge reduces….
Adverse Pressure Gradient
What two actions on a Aerofoil are needed to produce lift?
Upwash, and Downwash
Lift is _______ to the free stream flow.
Perpendicular
Drag is ________ to the free stream flow.
Parallel
Lift acts at the ______ __ _______ of an aerofoil
Centre of Pressure
If you double the speed of the airflow over an Aerofoil, you _______ the lift.
Quadruple (x by 4)
If you increase the speed of airflow over an Aerofoil, Magnitude ______ and Distribution of forces ______
Magnitude Increases
Distribution of forces stay the same
Changing the angle of attack will ______ magnitude of the forces and the distribution of forces will _______
Increase
Change
When increasing the AoA on a Cambered Aerofoil, the Centre of Pressure will ________
Move closer to the Leading Edge
The Centre of Pressure on an aerofoil is roughly how far along the total length?
25%
When decreasing the AoA on a Cambered Aerofoil, the Centre of Pressure will ________
Move further from the Leading Edge
When increasing the AoA on a Symmetrical Aerofoil, the Centre of Pressure will ________
Remain still
When decreasing the AoA on a Symmetrical Aerofoil, the Centre of Pressure will ________
Remain still
At 0 degrees AoA, a symmetrical Aerofoil will produce ________ lift
No
At 0 degrees AoA, a Cambered Aerofoil will produce ________ lift
Positive or negative lift, depending on its design.
To get zero lift on a positively cambered Aerofoil, we need a_______
Negative AoA.
Increasing the camber of a wing will…
Increase pressure differential between the upper and lower surfaces.
In a cambered Aerofoil, the pressure distribution is affected by ______ and ______
AoA and Camber
In Aerodynamic Force, q is
Dynamic Pressure
In Aerodynamic Force, S is
Surface area
Aerodynamic Force Coefficient is a __________ number/ratio
Dimensionless
Our force equation is
F = qSCF,
or
F = 0.5 * Rho * V^2 * S * CF
Our lift equation is
L = IAS^2 * S * CL
or
F = 0.5 * Rho * V^2 * S * CF
To maintain Lift, if IAS goes down….
AoA must go up
The Aerodynamic Force Coefficient in Lift is affected by what 3 things?
Angle of Attack
Camber
Thickness
In flight, we can change which of the items in out Lift Equation?
Lift
Speed
Angle of Attack (CL)
In our lift equation, V, IAS or TAS are given in what units?
m/s
In an Aircraft, at what point does lift act?
Centre of Pressure
In an Aircraft, at what point does drag act?
Centre of Pressure
In an Aircraft, at what point does Weight act?
Centre of gravity
In an Aircraft, where does Thrust act?
Through the centre of the engine
Engines below the couple created by the Centre of Gravity and Centre of Pressure, create a ______ ______ ______.
Nose up Rotation
Which must be further forward in an EASA Aircraft, CoG or CP?
CoG
The Critical AoA is the angle at which an Aerofoil…
Produces the Maximum Lift Coefficient.
Flying at the Stalling AoA will cause the plane to stall. True or False?
False, exceeding this angle will cause the aircraft to stall
At the Critical AoA, we say the Coefficient of Lift is
CLMAX
Our standard Stalling AoA on a Symmetrical wing is
16 Degrees
Adding thickness does what to the stalling AoA of an Aerofoil?
Increases the Stalling AoA
A cambered Aerofoil will have a ________ CLMAX than a symmetrical Aerofoil
Greater
Flaps are ______ ________ Devices
Camber Changing
As flaps go down, the ______ Increases
Camber
As flaps go down, and the Camber increases, what must change to maintain the CL?
AoA must reduce.
“Straight and Level means what cannot change?
Lift and IAS
Force Coefficient is the ratio of…
Surface Pressure:Dynamic Pressure
Form drag
The wake that is formed behind the wing
Skin drag
The drag in the boundary layer
The drag coefficient gives us a measure of drag per _____ _____ and unit _____ _____
Unit area
Dynamic pressure
Drag is a component of the _____ _____ and governed by the fundamental _____ force
Total reaction
Aerodynamic
The boundary lays
Area extending from the aircraft’s surface out to the point where the speed if airflow is 99% of the free stream flow
The transition point is where
Laminar flow becomes turbulent flow
The laminar layer is only ______ thick, it is _____ and has _____ _____
A few mm
Slippery
Low energy
The turbulant layer is _____ thick, it is _____ and has _____ _____
A few cm
Draggy
High energy
The separation point is where
The boundary layer separates from the upper surface. of the aerofoil.
There is more energy at the _____ of the boundary layer.
Base
A low Reynolds no. means (<500,000)
Lamina flow
A high Reynolds no. means (>10,000,000)
Turbulent flow
The transition point is 1/3 in front of the ______ ______ _____ or 2/3 behind the _____ _____
Point of maximum thickness
Leading edge
In lamina flow, _____ forces are dominant
Viscus
In turbulent flow, _____ forces are dominant
Dynamic
Aerodynamic drag
The force on an object that resists its motion
The more viscous the air
The greater the shearing force
All effects if skin friction drag take place within the
Boundary layer
The laminar boundary layer has a _____ velocity gradient
Shallow
The turbulent boundary layer has a _____ velocity gradient
Steep
Nose to tail axis:
Longitudinal - role
Wingtip to wingtip axis:
Lateral - pitch
Vertically through the fuselage axis:
Normal - yaw
Wingspan
The distance between the wingtips
Gross wing area
The planform of the wing and the area of fuselage between the wing roots.
Wing taper
When the tip is smaller than the root.
Taper ratio = _____/_____
Taper ratio= tip chord/root chord
Aspect ratio
The ratio of wingspan to average wing chord
Aspect ratio = _____/_____
Aspect ratio = Span/average chord
if highly tapered: Aspect ratio = Span²/wing area
Sweep angle
The angle at which the wing is inclined to lateral axis.
The more swept back a wing, the higher _____ you can cruse at
Mach no.
Mean aerodynamic chord (MAC)
The chord of an imaginary rectangular wing which has similar longitudinal stability properties to the actual wing
Angle of incidence
The angle between the chord line of the wing and the aircraft’s longitudinal axis.
Washout
Reduction the in angle of incidence from the root to the tip.
Dihedral and Anhedral angles
The angle of the wings relative to the aircraft’s lateral axis.
Dihedral can be found on aircraft with wings angling
Upwards (e.g. A320, 737)
Anhedral can be found on aircraft with wings angling
Downwards (e.g. BAe 146)
Wing planform
The outline shape of a wing when seen from above
Wing tip vortices are formed when
Air travels from high pressure under the wing to low pressure above the wing by flowing around the wing tip.
Longer chord at the wingtip will result in
Greater vortex
Spanwise flow travels from _____ to _____ under the wing and _____ to _____ above the wing
Root to tip
Tip to root
The vortex spins _____ on the left wing and _____ on the right wing
Clockwise
Anti-clockwise
The intensity of the tip vortex depends on what 2 things:
The pressure difference above and below the wing.
The amount of time the driving force is given to operate on the air mass
A _____ _____ can only form when the wing is producing _____
Wing vortex
Lift
Tip vortices _____ with increasing _____ _____
Decrease
Forward speed
A low aspect ratio wing produces _____ _____ tip vortices than a high aspect wing ratio.
More intense
Trailing edge vortices ten to be weaker at the _____ of the wing.
Root
In 2D flow, the upwash and downwash are _____ in magnitude
Equal
In 3D flow, the upwash _____ and the amount of downwash _____.
Decreases
Increases
Downwash is greater at the _____ _____
Wing tip
Effective airflow
The combination of both horizontal and vertical velocities
The effective airflow determines the wings _____ _____
Aerodynamic forces
The component of aerodynamic force acting at ___ to the flow must be shown acting 90° to the _____ _____
90°
Effective flow
The angle between the Relative airflow and Effective airflow is called:
The induced angle of attack
Anything the effects the amount of downwash is going to ____ the effective airflow.
Steepen
The Component of the vector parallel to the relative airflow
Induced Drag
Induced drag always accompanies the production of _____
Lift
If the induced angle of attack increases, induced drag _____
Increases
The angle of attack is the angle between the aircraft’s _____ _____ and the _____ _____
Longitudinal axis
Relative airflow
The induced angle of attack the is angle between the _____ and _____ air flows
Effective
Relative
The induced angle of attack is larger when (2 things):
The aircraft is flying at a lower TAS
and/or
The vortices are stronger there for producing greater downwash.
The effective angle of attack is the angle between the _____ _____ and the _____ _____ of the wing
Effective airflow
Chord line
Small vortices result in _____ effective airflow angle, meaning a _____ effective angle of attack and a _____ induced angle of attack
Shallower
Larger
Smaller
The effective airflow angle will be _____ at the wing root and _____ at the wing tip.
Shallower
Steeper
The higher the aspect ratio, the _____ the lateral pressure gradient.
Smaller
3 Disadvantages to a high aspect wing:
Needs a stronger, heavier main spar to support the larger wing.
More prone to tip strikes during take-off and landing.
At higher speeds, induced drag is a small percentage of the total drag, so the aerodynamic advantages are less significant.
For a given _____ _____, a wing with an _____ pressure distribution is the most efficient.
Aspect ratio
Elliptical
An elliptical wing produces a _____ and _____ level of downwash across the wing.
Constant
Reduced
An elliptical wing produces a constant section ____ ____ across the _____ _____, the ratio is the same (1.0) across the _____ _____ _____
Lift Coefficient
Entire span
Entire wing span
A rectangular wing has large _____ _____ and _____ downwash towards the wing tips, giving sections towards the wing tip a _____ effective angle of attack.
Wingtip vortices
Greater
Smaller
Static stability
The immediate response
Dynamic Stability
Subsequent response over time
Positive static stability
The initial tendency of an object
Neutral static stability
Object not wanting to move
Negative static stability
Moving further from its original position
Positive dynamic stability
Object returns to it’s original position
Neutral dynamic stability
Object will not settle
Negative dynamic stability
The object will move further away from it’s original position
Positive static stability can lead to…
Positive, Neutral and Negative dynamic stability. With neutral and negative in a periodic motion, and positive in both an aperiodic and periodic motion.
Neutral static stability can lead to…
Only Neutral dynamic stability in an aperiodic motion
Negative static stability can lead to…
Only Negative dynamic stability in an aperiodic motion.
Rolling/yawing to the right is _____ motion
Positive
Pitch occurs on the _____ axis and has _____ stability
Lateral
Longitudinal
M
Yaw occurs on the _____ axis and has _____ stability
Normal
Directional
N
Roll occurs on the _____ axis and has _____ stability
Longitudinal
Lateral
L’
On a symmetrical aerofoil the Aerodynamic center (AC) occurs at _____ chord
~25%
On a Chambered aerofoil the AC occurs at _____ chord
23 - 27%
An aircraft is more stable with stick _____ rather than stick _____
Fixed
Free
The absolute AoA is…
The angle between the RAF and the Zero lift line, it nullifys the effect of the camber
The zero lift line is always _____ the chord line on a positively cambered wing
Above
Up-gusts _____ the AoA
Increase
Down-gusts _____ the AoA
Decrease
The AC is _____ the CG
Behind
Pitching moment coefficient equation:
Cm = M / q S c
The greater the dynamic pressure
The faster you go
To increase longitudinal stability:
Increase the horizontal stabiliser size
Move CG forwards
Increase tailplane volume.
The forward CG limit makes sure:
Aircraft is not too stable
There is a minimum level of controllablity
The aft CG limit makes sure
Aircraft is not too controllable
There is minimum level of stability
The neutral point is
the point that the plane reacts around for stability. It is always behind the CG
The further from the CG the Neutral point is…
the greater the stability
Arm to NP
the distance between the current CG and the NP
Static margin
the distance between the aft CG limit and NP
CG range
the distance between the forward CG limit and the aft CG limit
The neurtal point is _____ _____ when the flaps are extended, due to the reduction of _____ _____ at the tail.
furthest forward
dynamic pressure
With stick position stability, as you go faster, there is _____ deflection of the elevator so the stick moves _____
Less
forward
With stick position stability, as you go slower, there is _____ deflection of the elevator so the stick moves _____
more
backwards
With a trim-tab system, stick position stability….
stays the same
With a trimmable horizontal stabiliser, stick position stability…
Changes
The aerodynamic center must be _____ the CG to have a positive position stability
Behind
Stick force stability
the further from the center position you move the stick, the greater the force should be
The more trim you have, the _____ the force will be on the stick
Greater
The further forward the CG, the _____ the stick force. The further aft the CG, the _____ the stick force
Greater
lighter
The stick force per G will be greater on a _____ aircraft than an _____ aircraft
Transport
Aerobatic
Aerodynamic dampening
After the initial down-force of the tail, the down-force will get smaller due to the airflow angle
At a lower alt./slower TAS there is a _____ airflow to the tailplane compared to a higher alt./faster TAS where there is a _____ airflow to the tailplane. Therefore aerodynamic dampening is less at _____ _____
Steeper
Shallower
High alt/faster TAS
TAS is __ the IAS at _____, so the stability is ___.
x2
40,000ft
1/2
Short oscillations are due to _____ positive dynamic force and Long oscillations are due to _____ positive dynamic force
Strong
Weak
Short oscillation features:
1 -2 secs
not much alt. difference
not much speed difference
Long oscillation features:
(phugoid) 1 - 2 mins Increase in airspeed when going down Decrease in airsped when going up Larger change in height
As Static stability increases, dynamic stability _____.
decreases
Nose to the left =
+β
Nose to the right
-β
Nose to the left of RAF - sideslip to the _____
Right
Nose to the Right of RAF - sideslip to the _____
left
Yaw moment coefficient equation:
Cn = N / qSb
The greater the volume, the _____ the directional stability
greater
The greater the swept back angle, the _____ the stability
greater
Dorsal fins _____ lateral stability and _____ direction stability.
Increase
Increase
Ventral fins _____ lateral stability and _____ direction stability.
Reduce
Increase
Stakes _____ stability
Increase
The fuselage can give off a _____ moment
De-stabilising
Lateral stability
The stability in a roll
Dihedral wings provide _____ stability
Positive
Weak lateral and strong directional stability can lead to a _____ _____
Spiral Dive
Strong lateral and weak directional stability can lead to a _____ _____
Dutch roll
Stability _____ with altitude
decreases
The propeller disk represents the __________
Plane of rotation
The angle between the plane of rotation and the chord line
Blade angle
The angle between the Plane of rotation and the Relative airflow
Helix angle
The angle between the Relative airflow and the chord line
AoA
The name for the distance between the start point actual distance traveled.
Effective pitch
The name for the distance between the start point and the Theoretical distance traveled
Geometric pitch
Distance between the Actual distance traveled and the theoretical distance traveled.
Slip
The _____ _____ determines the geometric pitch
Blade angle
The _____ _____ determines the effective pitch
Helix angle
For a fine pitch you need a _____ blade angle
Small
For a coarse pitch you need a _____ blade angle
Large
Torque force is…
the opposite of what the engine is trying to do.
The helix angle for the time is _____ than the helix angle for the hub.
Greater
The faster you go the _____ the helix angle
Greater
___ is the optimum blade angle
4°
____ is the max. blade angle
16°
If you increase the RPM, the helix angle will get ____
Smaller
High TAS, Low RPM results in
Reverse thrust
Fixed pitch propellers
Blade angle is fixed, simplest form
Two pitch propellers
Pilot can set either a fine or a coarse pitch
Adjustable pitch propellers
Blade angle can be adjusted mechanically on the ground, but then acts as a fixed pitch propeller at that fixed setting
Constant speed propellers
One that automaticaly adjusts it’s blade angle at different flight speeds to maintain the ideal AoA
The smaller the AoA on a prop blade, the _____ the drag
Greater
During take off, the prop is at _____ pitch
Fine
As the TAS increases the blade should become more _____
Coarse
The blade angle of a fixed pitch prop increases when RPM _____ or TAS _____
Increases
Decreases
Windmilling
When the engine has failed but the blade is still spinning and producing drag
Feathering
Increasing the pitch of the blade to reduce drag
To increase the pitch of the blade, you need to _____ the RPM by moving the pitch leaver _____. This takes the blade to a _____ position
Reduce
Backwards
Coarse
For a variable pitch prop, the faster you go, the _____ the pitch
greater
To increase torque absorption you need to _____ blade solidarity. We can do this by:
Increase
Increasing no. of blades
increasing the chord.
Beyond 6 blades, we lose efficiency because
They interfere with the flow of the flowing blade.
Propellers with more than one hub are known as
Contra rotating propellers
Torque reaction effect is:
Where the engine wants to spin the aircraft in the opposite direction of the prop
The heavier you are, the _____ the roll rate due torque reaction
Slower
The greater the blade size, the _____ the torque reaction
Greater
The more power you have, the _____ the torque reaction
Greater
Consequences of torque reaction on take-off:
Thrust is at its greatest so torque is at its greatest
Heavier on the left wheel and lighter on the right, causing yaw to the left on the runway.
Slipstream effect:
Airflow flips around around the body due to prop wash and hits the fin at an angle, pushing it to the right and causing yaw to the left.
It also rolls the tail to the right.
The slipstream effect is greatest at _____ power setting and _____ speed.
High
Slow
Asymmetric Blade Effect - P Factor:
As aircraft’s AoA increases, the prop disk has a greater angle which results in the down-going blade producing greater lift. This produces a yaw to the right.
Gyro effect:
Produces a force 90° to the point where the force is produced.
Prop icing forms towards the _____. It can reduces the efficiency by up to ___
Hub
20%
With a left engine failure, the aircraft will yaw to the _____.
left
Factors that affect the size of the yawing moment:
The amount of thrust being generated by the left engine
The distance the live engine is from the aircraft’s CG
The size of any additional drag moments caused
On a prop aircraft with 2 engines, more _____ will be provided on the wing with working engine and there would be more _____ on the dead wing. This causes the aircraft to _____ and _____ towards the _____ wing. If this is not stopped, the aircraft will enter a _____ _____
Lift Drag Roll yaw Dead Spiral dive
The two methods to gain equilibrium from asymmetric flight
The wings level method
The banking method
The wings level method:
Apply rudder to balance the moments
Disadvantages of the wings level method:
Increases drag from the fin, reducing limited excess thrust + performance.
Fin must be set at a large AoA to produce sufficient force . - chance of fin stall
The banking method:
Applying no more than 5° bank towards the live engine.
Disadvantages of the banking method:
In-balance of the slip indicator
More chance of disorientation
advantages of the banking method:
Less drag
less risk of fin stall
For directional control, you have better control at ____ altitude and _____ temperature
High
High
The critical engine:
The engine that, if it fails, results in the largest yaw moment produced by the remaining engine.
The factors determining which the critical engine is:
Length of the moment arm from the thrust lines
slipstream effects
Torque reaction effects
Weathercock tendency
On a prop aircraft with a right down blade, the ____ engine is the critical engine
left
With a jet the direction the wind is _____ _____ is the critical engine.
coming from
On a 4 engine jet aircraft, the __________ engine is the critical engine
outboard into-wind
Minimum control speed:
the minimum speed required for directional control
Vmc
airborne minimum control speed
Vmcl
landing configuration minimum control speed
Vmcg
Ground minimum control speed
Vmc is determined by:
min. thrust
Aft CG (most unfavorable)
trimmed for take-off
Max. take-off weight
most critical take off configuration (with gear up)
aircraft is airborne and out of ground effect
If prop - dead engine is windmilling, (if auto-feather is available, feathered)
rudder pedal force must not exceed 150lb
Vmcl is determined by:
Maximum thrust Aft CG (most unfavorable) Aircraft trimmed for approach min. weight (most unfavorable) most critical landing configuration minimum roll of 20° in 5 secs towards live engine rudder pedal force must not exceed 150lb
Vmcg
Maximum thrust Aft CG (most unfavorable) Aircraft trimmed for take-off min. mass (most unfavorable) most critical take-off configuration maintain control with rudder only, max. 30ft deviation from the center line
Mach no. equation
M = TAS/LSS
LSS equation
LSS = 39 x √absolute temp(k)
As you get higher, the LSS will get _____
smaller
subsonic
Mach no. <1
sonic
mach no = 1
supersonic
mach no. >1
M0.4 is the point where
compressablity takes factor
Mcrit
The point where the first LSS reaches supersonic
Transonic
Where some LSS are subsonic, some sonic, some supersonic
Mdet
The point where all LLS become supersonic
Fist shockwave created:
Normal shockwave
A normal shockwave is caused by
Partials where mach >1 collide with partials mach <1
The mach no. is a _____ behind the shockwave, with a distance of _____
reciprocal
0.0025mm
The faster you go, the _____ the drag from the shockwave.
greater
Oblique shockwave
Supersonic flow in-front and behind shockwave, just slower supersonic flow behind
Oblique shockwaves occur at
the leading and trailing edge
Bow wave:
Oblique shockwaves above and below the wing, a normal shockwave by the leading edge due to the stagnation zone
Ailerons outside of the mach cone are _____
ineffective
In expansion waves there is:
greater static pressure colder air less density faster moving air No change in energy
Expansion waves effects:
Increases - Mach Decreases - Ps density temperature Pt stays the same
Norma/oblique waves effects
Decreases - Mach Pt Increases - Ps density temperature
Mdetached occurs at
1.3 mach
Operating MMO
The max. mach no. - climbing
Operating VMO
the max. calibrated speed - descending
The is more pressure differential _____ of the shockwave
in-front
When going through Mcrit, initially:
Cl slightly increases and Cd slightly decreases
After -
Cl significantly decreases and Cd significantly increases
Shock stall -
The point when the lift coefficient, as a function of Mach no., goes beyond it’s maximum value.
At MFS = 1.0 -
Cd drops
Oblique shockwaves form at the trailing edge
Mach tuck -
Cp moves back
Points nose down. increases speed - exceeding max. operating speed
Tailplane becomes less effective due to increase in turbulent air coming off the wing.
Mach trim
When approaching transonic, trims horizontal stabiliser to avoid mach tuck
Super-critical wings do
Mcrit differed
delays Mdrag divergence
Allows us to travel faster
Mach buzz
felt through controls when approaching Mach 1.0 due to formation of a shockwave
High-speed buffet
High speed tumbling wake may hit the airframe/horizontal stabiliser causing buffet.
For a greater margin between high-speed buffet and low speed buffet you should…
descend to a lower altitude.
Aerodynamic ceiling
Altitude at which you’ll either enter a high speed stall or a lowspeed stall.
Transport aircraft load limits
Positive: 2.5g
Negative: -1g
Ultimate: 3.75g
Utility aircraft load limits
Positive: 4.4g
Negative: -1.76g
Ultimate: 6.6g
Aerobatic load limits
Positive: 6g
Ultimate: 9g
the ultimate load is ___ more than the load limit
50%
in level flight, the load factor is ___
1
VA
The highest speed at which sudden, full-up elevator deflection can be made without exceeding the limit load factor.
VA equation
VA = VA(current) x √New weight/old weight
With flaps extended, the maximum load limit is reduced to ___ on a transport aircraft
2g
VB
The design speed for maximum gust - up to 66fps at 20,000ft
Faster than VA, Slower than VC
Vc/Mc
Maximum permissible cruise EAS/Mach no.
Always exceed VMO/MMO
Must withstand gusts of 50fps
VD
the speed increase from Vc/Mc where the areoplane is flow for 20 secs along a flight path 7.5° below the initail path and then up at a load factor of 1.5g.
Withstand gusts of 25fps
VNE
Never exceed speed (light aircraft)
VNO
Max. structural cruise speed
VLE
Max. landing gear extended speed
VLO
Max. landing gear operating speed
VFE
Max. flap extension speed
VRA
Rough air speed (35kts less than VMO)
Recommended penetration airspeed
- Fast enough to avoid stalling
-Slow enough to avoid structural damage
Conditions affecting the load factor
Rectangular wing effected more
Light aircraft effected more
Faster airspeed effected more
Low altitude effected more
New LF equation
Increase in LF x (New speed/ old speed)
High speed aileron Reversal
Aileron reversal due to large aerodynamic forces twisting the wing when aileron is moved.
A contaminated wing effects
Reduce stalling AOA Reduce Cl Increase Stall Speed Increase Drag Climb performance decreases
Ice tends to accumulate at speeds below _____ IAS and lower altitudes in visible mosisture and between ___ and ___
250kts
0 - 20°C
_____ aircraft are more susceptible to ice
Prop
