Drag Flashcards
is all drag bad?
no lol wtf
what are the subparts of total drag?
parasite drag and induced drag
what are the subparts of parasite drag?
profile drag and interference drag
what are the subparts of profile drag?
skin friction and form drag
what is the laminar flow?
the smooth sheet of air over an aerofoil, about 2-3mm thick
what is the turbulent flow?
the flow after the transition point, where air separates from the aerofoil and becomes turbulent
where is the transition point in the boundary layer?
generally at the point of max thickness
what is skin friction drag?
drag induced by the shear stress of the layers within the boundary layer
what is shear stress?
like when you run your hand across a stack of cards and the higher ones move but the bottom ones stay still, its bc of air viscosity and the RAF dragging the boundary layer with it
smoother surfaces result in (less/more) skin friction drag
less !
bigger aerofoils create (more/less) drag?
more - measured in Reynolds Number
higher AoA results in the transition point of the boundary layer moving (forward/backward)
forward
what is form drag?
drag induced by the shape of an aerofoil - a fucking square is gonna be way less aerodynamic than a nice lil dart yk???
what is the separation point in relation to form drag?
the point where airflow separates from the body of an aerofoil and gets turbulent and silly
low AoA results in a very (far back/far forward) separation point
far back - less form drag overall
what is a fairing?
a streamlined shape added to the sharp edges of an aircraft - like where the wing connects to the fuselage - to reduce form drag
ice accretion can greatly (increase/reduce) form drag
increase
form drag is lower at (high/low) speed
low
speed overrules AoA in relation to form drag - true or false?
true asf you go girl
what is interference drag?
drag induced by the sharp edges on the wetted area of an aircraft - like where the wingroot meets the fuselage. this is reduced with fairing
what is induced drag?
induced drag is drag induced by the production of lift. basically a part of lift lol
how does induced downwash do its thing in relation to induced drag?
more downwash results in the AoA being forcibly reduced, resulting in less TR and therefore less lift
whats the equation for induced drag?
CL^2
(fixed ratio) (wing efficiency factor) (AR)
what is washout?
a decreased angle of incidence at the wingtips to reduce induced drag, when combined with taper
list the wingtip modifications used to reduce wingtip vortices
drooping wingtip, winglet, wing fence, wingtip tank
whats the equation for the coefficient of total drag?
CD = CD parasite + CD induced
whats the formula for drag?
Drag = CD 1/2pV^2 S
total drag is (high/low) at slow speeds
low
go look at the lift/drag ratio table on page 5-16
go bro
