M11.1 Flashcards
What are the main three axis?
- lateral axis
- longitudinal axis
- vertical axis
What is the motion around the lateral axis?
Pitch
What is the motion around the longitudinal axis?
Roll
What is the motion around the vertical axis?
Yaw
What are the primary flight controls?
- ailerons
- elevators
- rudder
What may be added on larger aircraft to increase efficiency of ailerons?
Roll spoilers
What are the secondary flight controls?
- slats
- flaps
- spoilers
- trim systems
What are primary flight controls used for?
To safely control the aircraft
What are secondary flight controls used for?
To improve aircraft performance
What side would the roll spoilers deploy in a turn if the aircraft has them?
On the wing with upward aileron deflection
Why would you use less aileron at high speed?
Because it has a larger affect
What is a stabiliser also known as?
All-moving tail
What is a canard?
A fuselage mounted, horizontal surface that provides longitudinal stability and control
What are the two types of canard?
Lifting-canard and control-canard
What does a lifting-canard do?
It shares some of the weight with the wings
What is the job of a control-canard?
It is used for pitch control during manoeuvring
Why is a rudder limiter system used?
To prevent rudder overload
What is the maximum rudder travel at 150 knots?
30°
What is the maximum rudder travel at 150-200 knots?
15°
What is the maximum rudder travel at 200 knots?
5.7°
What is a ruddervator?
A combination of rudder and elevator
How does a ruddervator work?
Both flaps move in one direction it is a elevator and when they’re opposite direction its a ruder
What is a elevon (delta wing)?
A combination between a elevator and aileron
How does a elevon work?
Both flaps move in one direction it is a elevator and when they’re opposite direction its a aileron
What are the two types of lift devices?
Slats and flaps
What are the two types of drag devices?
Speed brakes and spoilers
When are flaps mainly used?
Low speed landings
What’s the percentage increase of lift from a plain flap?
55%
What’s the percentage increase of lift from a split edge flap?
65%
What’s the percentage increase of lift from a slotted flap?
70%
What are slots in the wing used for?
To prevent flow separation
What’s the percentage increase of lift from a fowler flap?
95%
What’s the percentage increase of lift from a slat?
35%
Where are air brakes located?
Where aircraft structure is strong enough to withstand heavy air-loads
What is spanwise flow?
When air flows over the wing and towards the wing tip
What does spanwise flow do to the boundary layer?
Thickens it towards the wing tip
What is used to prevent spanwise flow?
Wing fences and saw tooth wings
What are wing fences also known as?
Boundary layer fences
What are vortex generators used for?
Improving boundary layer control
How does a vortex generator work?
It takes high energy form above and puts it into the boundary layer
Where are stall stripes located?
wing root of the leading edge
Why are stall strips used?
It forces a wing root stall before a wing tip stall
Why is the trim system used?
To compensate imbalance
What does a ruddervator need?
A mixer unit
What are balance tabs used for?
They change the camber and assists the deflection of the control surface
What is the disadvantage of a balance tab?
Reduces efficiency
Why are anti balance tabs used?
Increases efficiency but is harder to deflect control surfaces
What is a control tab?
A tab controlled by the pilot
What is a trim tab?
It is used to compensate for imbalance
What is the speed of sound?
The distance traveled by sound in a unit of time
What is the speed of sound in dry air?
343.2metres per second
How fast does the speed of sound travel in gases, liquids, solids?
Most slowest in gases, fast in liquids, faster in solids
What are the three speed regions?
- subsonic
- transonic
- supersonic
What is said about air in the subsonic region?
It is incompressible
How fast are speeds in the subsonic region?
Below the speed of sound
How fast are speeds in the transonic region?
Some are below and some are above the speed of sound
How fast are speeds in the supersonic region?
Above the speed of sound
Air pressure can change without changes in what?
Air density
What does a shockwave produce?
Large pressure and density changes
If the air is compressed what is the resultant?
Shock waves form
What is the speed range for subsonic?
Anything below 0.8 mach
What is the speed range for transonic?
Between 0.8-1.2 mach
What is the speed range for supersonic?
1.2-5 mach
What is the calculation for mach number?
Aircraft speed
——————
Speed of sound
What is critical mach?
The highest mach number you can have without supersonic flow
What mach number does a normal shock wave take place at?
1.2 mach
What does a normal shock wave create behind it?
A large increase in static pressure
Flow separation reduces what?
Lift
What forms at the leading edge when the flight speed exceeds the speed of sound?
A bow wave
What is wave drag?
Drag caused by shock waves
What do shockwaves turn useful energy into?
Heat energy
What are the two ways to reduce wave drag?
Vortex generators and the area rule
What are wings specifically designed to do?
To be strong enough and hold fuel tanks
What angle are most wings swept at?
30°
Why are wings swept?
Reduces thickness and increase critical mach number
What are the characteristics of a transonic profile?
- flatter upper surface
- more curve leading edge
- thinner trailing edge
What is the diffuser effect?
When velocity in airflow reduces and static pressure increases
What is a wing with a transonic profile also known as?
Rear loaded wing
What does having a greater wing chord thickness also increase?
Fuel capacity
Why does the shockwave appear on the wing root first?
Because its the thickest part
What is a stall due to going too fast known as?
Shock stall or high speed stall
What effect is caused by a shock stall/ high speed stall?
Tuck under effect
What is used to correct the tuck under effect/
The horizontal stabiliser
What is the mach trim system?
When the horizontal stabiliser works automatically to prevent tuck under
What happens if you operate a elevator at transonic or higher?
It has the opposite effect to normal
What are the two types of waves formed in supersonic flow?
Shock waves and expansion waves
What are the two types of shock waves?
- normal shock waves
- oblique shock waves
What type of wave doesn’t touch the aircraft structure?
A normal shock wave
What happens to airflow direction that passes through a normal shock wave?
There is no change
What happens to velocity of airflow passing through a normal shock wave?
It reduces to subsonic
What happens to airflow velocity after passing through an oblique shockwave?
I reduces but stay supersonic
When is an oblique shockwave formed?
When the supersonic air-stream turns into a new flow direction
When is an expansion wave formed?
Where supersonic air turns away from the preceding flow direction
What happens to. Airflow velocity after passing through an expansion wave?
It increases
What are the two typical profiles?
- double wedge profiles
- circular arc profile
Where is lift located on a profile passing through supersonic flow?
Approximately 50% along the chord
Where is lift located on a profile passing through subsonic flow?
Approximately 25% along the chord
What speed must air be for it to enter the compressor stage?
Subsonic
How are temperature increase caused?
Friction between the surface and high velocity of the free air-stream
At supersonic flight temperature can affect what?
The aircraft structure
What temperature does aluminium alloy lose approximately 80% of its strength?
250C
