M8.2 Aerodynamics Flashcards
Can a flying body attain speeds to compress air in subsonic region?
No
Air is incompressible
The continuity equation states that speed of airflow is inversely proportional to what?
To the area of the cross section of the tube if density remains constsnt
A (diffuser) outlet is used when diameter does what and speed does what?
Diameter increases
Speed decreases
A (jet) outlet is used when diameter does what and speed does what?
Diameter decreases
Speed increases
At the point of stagnation speed is what and static pressure equals what?
Speed is zero
Static pressure equals total pressure
What is laminar flow?
When particles in the fluid all flow parallel to one another with no turbulence
What part of the wing is a safer part to have stall?
Root
What is the angle called between effective airflow and relative airflow known as?
Induced alpha
(Angle of attack)
Wash in states that angle of incidence is greater towards what?
Wing tips
Wash out states angle of incidence is greater towards what?
The root
What is downwash?
After passing over aerofoil the fluid flow returns to original state
During upwash where does the air turn?
Towards the low pressure region on the upper surface of aerofoil
What is a chord line?
Imaginary line connecting leading edge and trailing edge
Describe geometrically twisted wing?
Camber of the profile is constant
But angle of incidence is greater at root than tip
Describe aerodynamically twisted wing?
Camber of profile at root is greater than the camber at the tip
Angle of incidence is constant across wingspan
Chord lines parralel
What is the Angle of Attack?
the angle between the chord line of the profile and the relative wind.
What is the angle of incidence?
the angle between the chord line of the profile and the longitudinal axis of the aircraft.
What is the centre of pressure?
the point on the chord line where the total sum of a pressure field acts on a body.
What is the sweep angle?
Angle between the line of 25% chords and a line perpendicular to the root chord
Why is a wing swept back?
To increase stability
3 types of drag?
Induced drag
Parasite drag
Compressible drag
3 types of parasite drag?
Form
Friction
Interference
What is induced drag?
The drag on the wing caused by lift
What is parasite drag?
Not related to lift, caused by distribution of pressure, skin friction or aerodynamic interference
What is compressible drag?
Caused by shock waves on an aircraft approaching the speed of sound
For stable flight whereshould centre of lift be?
Behind centre of gravity
What does Mac stand for?
Mean aerodynamic chord
What wings stall at tip?
Tapered
Swept
Equation for coefficient of lift?
Measured lift/ theoretical lift
Advantage of high maximum coefficient of lift?
Aircraft can fly slowly
