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
