M8 New Flashcards
What makes up air
21% Oxygen
78% Nitrogen
1% Other gasses
Average height of the atmosphere
760km
What are the 5 main regions of the atmosphere
- Troposphere
- Stratosphere
- Metosphere
- Thermosphere
- Exosphere
What is the lowest of all of the atmospheres
Troposphere
Which atmosphere contains the ozone layer
Stratosphere
What is the atmospheric pressure at sea level
14.7psi
What is used to measure air pressure on the ground
Barometer
What is dynamic pressure measured in
Newtons per square meter
What is static pressure measured in
Bar or Pascal
ISA at sea level
1013.25hpa
Temp at sea level
288.15k or 15 degrees c
what is the density at sea level
1.225kg/m cubed
Speed=
Time
What is the point of stagnation
Static pressure = total pressure and there is no flow
What is laminar flow
Smooth undisturbed flow
What is relative airflow
Airflow with respect to the object flowing through it
What is a disadvantage to laminar flow
Due to low kinetic energy it is easier for flow to separate
What is the chord line
A straight line connecting the leading edge and the trailing edge
What is the mean camber line
Equidistant between upper and lower surface
What is the maximum camber line
Greatest distance of the mean camber line from the chord line as a %
What is fineness ratio
Also known as thickness ratio
Maximum thickness or depth of a section expressed as a % of the chord from the leading edge to trailing edge
What is aspect ratio
Width of wing
What charictaristics do high aspect wing have
Long spans
What is induced drag affected by
- Aspect ratio
- Wing tip design
- Aircraft speed
What is wash in
Angle of incidence is greater towards wing tips
What is wash out
Angle of incidence greater at the wing root
What is the Mean Aerodynamic Chord
The average chord length of a tapered or sweet wing
What is Angle of attack
Between the chord line of the profile and the relative wind
What is the angle of incidence
Between the chord line of the profile and longitudinal axis the aircraft
denoted by Gamma
What is the centre of pressure (centre of lift)
The point on the chord line where total sum of pressure acts on a body
Where is the Centre of pressure at normal cruising speeds with slight positive angle of attack
25% back along the chord line
What angle is max angle on an aerofoil before flow separation occurs
15-18 degrees
Where would a rectangualr wing stall first
Root first
Where would a tapered wing stall first
tip
Hight down wash =
Low angle of attack
Low downwash =
High angle of attack
Which point on an elliptical wing would stall first
Entire wing stalls at the same time
What is the most common wing type on most modern commercial aircraft
swept
Which direction would the wings face is they have positive sweep
Backwards
Which direction would the wings face if they had negative sweep
Forwards
What is sweep angle
Angle between the line of 25% chords and a line perpendicular to the root
The more swept back the wing the more stable it is on which axis
Roll
What is the critical mach number
The speed at which shock waves begin to appear or where airflow reaches speed of sound ( Normally on top of the wing because the air travels faster)
What is the main disadvantage of swept wing
Poor lift to drag ratio
What is the main advantage of a swept wing
Only beneficial for aircraft flying close or above the speed of sound
What is dihedral angle
When the wing tip is higher or lower than the wing root
Dihedral angle increases what kind of stability
Roll
What is anhedral (Negative dihedral)
Wing tip lower than root
What type of aircraft would anhedral wings be used
Aircraft with high centre of gravity
What is Induced drag caused by
Lift
What are the different types of Parasite Drag
- Form
- Friction
- Interference
What is the main kind of compressible drag
Shock waves
What is Parasite/Form drag caused by
Pressure distribution on a body
How is Form drag reduced
‘Streamlining’ by adding a bullet shaped nose and fairings
What is the relationship between form drag and friction drag
A profile that has low form drag has high friction drag and vice versa
How can interference drag be reduced
Fairings
When does compressible drag occur
Only in the transonic and supersonic regions (caused by shock waves)
What is total drag
Induced drag + Parasite drag
What is Fineness ratio
(Or thickness ratio) Maximum thickness of the chord as a fraction
What are the 4 fundamental forces that effect normal flight
- Lift
- Weight
- Drag
- Thrust
What is the equation of coefficient of lift
THEORETICAL LIFT
What is the equation of coefficient of drag
THEORETICAL DRAG
What happens if AOA increases above Alpha max
Flow separation or stall occurs
What is the advantage of high max lift coefficient
Aircraft can fly slowly
What kind of aircraft would Deep stall/super stall occur
Mainly on T tail aircraft and is the result of the wing stalling and then upsetting the airflow over the tail
What kind of input would a wing root stall require to recover
None from the pilot, it should recover itself
What kind of input would a wing tip stall require
A control movement from the pilot
What is the most dangerous type of ice
clear ice
High aspect ratio makes what kind of glide ratio
Much better glide ratio
What is total drag
The sum of induced drag and parasite drag
In which way does centrifugal force act
Opposite to lift
What is the equation of Load factor
n=Lift in turn
—————
Weight
What is the aeroelastic limit also known as
Redline airspeed
What are structural limits also referred as
- Acceleration limits
- Limit load factors
Ultimate structural limit is what % of the normal structural limit
150%
When would lift augmentation devices be used
At slower speeds
Plain flap increase by how much of lift
50-55%
Split flat increase in lift by how much
60-65%
Slotted flap increase in lift by how much
65-70%
Fowler flap increase in lift by how much
95%
What type of flap gives most lift
Fowler
Slot increase in lift by how much
increase max coefficient of lift by 40%
What are Vortex generators for
Boundary layer control
What are the main benefits of winglets
- Reduced fuel consumption
- Increased Range
-Improved performance - Lower emissions
Directional stability control done by
- Dorsal fin
- Keel surface
- Wing sweep