106 Through First Exam Flashcards
Characteristics of the Clark-Y Airfoil
Standard in the 1920-1930
Almost flat lower camber
! What does planform mean? !
Shape of wing as viewed from above
! Which wing shape is best? !
It depends on what the mission is
What is the aspect ratio
ratio of wing span to wing chord
What is taper?
Decrease from wing root to wingtip in wing chord or wing thickness
Do faster planes have big or small aspect ratios
small
Rectangular wing pros:
cheap and easy to produce
easy/cheap to maintain
rectangular wing stall characteristics:
advanced stall warning
stalls at root
Moderate Taper wing stall characteristics
whole wing stalls at once
High taper wing stall characteristics:
stalls from wing tips first
Pointed tip wing stall characteristics:
stalls from wing tips first
Sweptback wings cons:
Dutch roll
needs yaw damper
bad at slow speeds
tips stall first
Pros of swept back wings:
delays shockwaves allowing for flight closer to supersonic speeds
very efficient at high speeds
What is the most efficient subsonic wing?
elliptical wing
Elliptical wing stall characteristics:
little warning
entire wing at once
What principle accounts for 90% of wing lift?
Brenoulli’s principle
What is an airfoil?
any lift creating surface
What is camber?
the curve of the wing
What is the aspect ratio?
Span/chord
What is the span of a wing?
length of wing
What is the chord of a wing?
width of wing
What is the dihedral angle
angle of wing from plane to tip
What is the mean camber line?
mathematical imaginary line formed by subtracting distance from chord line to lower camber from the distance from chord line to upper camber
what is the mean aerodynamic chord?
distance between leading and trailing edge, measured parallel to normal airflow over wing
Why is knowing the max camber important?
Correlates directly to where lowest pressure is located
Center of gravity needs to be kept in front of the center of lift in order to stay stable
What is skin friction drag?
air sliding across surface sticks to it, as no surface is completely smooth
what is interference drag?
drag from turbulence where surfaces meet at 90 degrees
What is pressure drag? (form drag)
air striking surface makes drag
drag caused by separation of airflow
What is induced drag?
Drag as a result of lift
What is ground effect?
an effect that happens less than one-half wingspan above ground
air is forced down and there is a significant decrease in induced drag
What is the boundary layer
layer at which air does not curve to shape of wing anymore
What do wing fences do
prevent entire wing from stalling at once
Obstructs span wise flow