Aerofoils Flashcards
What is the chord line?
A straight line joining the leading and trailing edges
What is the chord length?
The distance between the leading edge and trailing edges measured along the chord line
What is the mean camber line?
A line drawn midway between the upper and lower surfaces of the aerofoil from the leading edge to the trailing edge
What is the max camber?
The max distance between the mean camber line and the chord line (usually the larger part of the aerofoil/upper camber)
What is the thickness of an aerofoil?
The ratio between the chord and the length of the aerofoil
What is the angle of attack?
The angle between the chord line and the direction of relative airflow (RAF) to the aerofoil
What is the angle of incidence?
The angle between the chord line and the fixed aircraft datum line
Define ‘span’
The distance from wing tip to wing tip
What is aspect ratio?
The ratio of span to chord: Span/Chord
or if the wings are of not constant chord:
Span²/Chord
What is wash out and wash in?
Wash-out: A decrease in the angle of incidence towards the wingtip.
Wash-In: An increase in the angle of incidence towards the wingtip.
What are upwash and downwash?
Upwash: The upwards flow of air before reaching the aerofoil
Downwash: The downwards flor of air after passing the aerofoil
What happens to the centre of pressure as the AoA is increased towards the stall angle?
- The CoP moves progressively forward with increasing AoA up to the stall angle.
- It will then move rapidly rearward, the range of travel is approximately 20%-30% the chord length
What, if any, effect is there on the CoP on a symmetrical aerofoil when the AoA is changed?
There is little/no movement in the CoP
As the angle of attack increases what happens to the total reaction, lift and drag?
They all increase together
