Wings Flashcards
Cross wing area
Area of whole wingspan from tip to tip. Also taking into account the bit of the area in the middle between the two wings
Taper ratio is?
The formula?
Ratio of wingtip chord to root chord.
TR=Tip chord
—————
Root chord
Average chord
& formula for wing area
The mean geometric chord length of the wing, at midpoint of wing, from leading edge to trailing edge.
Wing area= wingspan x average (mean) chord.
Aspect ratio
Ratio of wing span to the average chord.
Aspect ratio for rectangular wing =
SPAN / CHORD
Aspect ratio for tapered or swept wing =
Span^2
————
Area
Low aspect ratio will mean
A low CL, but higher AOA
Opposite for high aspect ratio
Sweep angle
Angle between wing and the straight latitudinal line going over aircraft at the root of the wing.
Disadvantages of a swept angle wing
Not all airflow meeting wing at 90⚫️ = less lift
Can lead to shockwaves on wingtips
Stall at wingtips
Advantages of a sweep wing angle
Can deal with critical MAC very well (high speed stuff)
Wind component
How much wind you’re able to use for lift
Wind component ratio
speed X cos(windsweep angle)
^airflow speed in m/s
Wind component
How much wind you’re able to use for lift
Wind component =
Air flow speed (m/s) X cos(windsweep angle)
Mac is
Percentage of a theoretical rectangular wing
Rigging angle
Angle from wing root slant to the longitudinal axis of aircraft.
Normally slightly positive angle
Angle of incidence
Angle between chord line of wing and a/c longitudinal axis. (Twists along the wing)
Washout
The slight twist given to wings, which reduces the angle of incidence from root to tip.
We have washout on aircraft to…
Promote stalling at root and not tips
Dihedral wing design
What’s the angle?
Wings go up.
Angle between wing & line of latitude of aircraft
Anhedral
It’s effect on an aircraft?
Wings point downwards from root.
Less stability, more controllability
Spanwise flow / tip vortices
High static pressure below wing moves to the wing tip to try and get to the low static pressure on top. As it tries to get on top, it is already propelled backwards. Creating tip vortices.
Port is
Left
Starboard is
Right
Looking from behind - an aircraft
the spanwise flow
port side goes
Starboard goes
Clockwise
Anti clockwise
Tip vortices does depend on
How long wing tip is.
If longer = more air, higher strength.
Higher speed, less time for vortex to form
Low aspect ratio will mean for tip vortices
Stronger vortices
If lift decreases, tip vortices,
Decrease
Trailing edge vortices
Back of wing. Caused by air flow on underside & on top of wing influenced by spanwise flows either going to edge of wing or to root. As air on each side differ in direction, when they meet at the trailing edge they create a vortices.
3D flow downwash is greater than 2D flow downwash because of
trailing edge vortices
As downwash increased, like a flat plate being pushed down from one side, the EAF (effective Air Flow) rises up, this causes
The lift to shift upwards and slant to the right - of the original lift position.
The angle between the EAF effective air flow, and the RAF relative air flow, is the
Induced AOA
As EAF effective airflow, increases upwards, the Effective AOA
Decreases. This is important as, AOA generates lift. Although on the contrary, too much AOA (e.g16⚫️) could cause a stall.
Faster you go, less induced drag as
Less downwash
Elliptical wing distribution generally means
More lift at wing root
Less lift at wing tip
A high aspect ratio means
Induced drag wise
Less induced drag
Elliptical wing design
But
Negative consequence
Almost equal lift distribution from root to wing tip.
If you stall, stall happens all over wing
Moderately tapered wing
Strong downwash at tip. Less at root.
Shaking that occurs at stall, occurs from
Turbulent Airflow separating from wing first at wing root, then hitting the aircraft tail.
Swept wing means
Will stall at the tip
increased lift at wing tip
A camber change will result in
Smaller downwash, as less disturbance at the wing tip
Frames of reference
Airflow to ac
Ac to airflow
Wing loading formula
Weight of ac
/
Wing area
2 main types of drag
Non-aerodynamic drag (PARASITE DRAG) & aerodynamic drag
Aerodynamic drag consists of
And what is it?
Induced drag
The force on a force that’s resisting.
Parasite drag consists of
Form drag - pressure gradient
Skin friction drag - mechanical drag
Interference drag - airflow hitting it self all over the ac surface
Form drag + skin friction drag make up
Profile drag
As speed increases,
Parasite drag…
Induced drag…
Increases
Decreases
High aspect ratio means a larger or smaller area of wing tip?
Smaller.
