Wing Design Flashcards
How does aspect ratio affect the pressure gradient
Higher aspect ratio = smaller pressure gradient
What affect does a higher aspect ratio have on landing characteristics
More chance of tip sticks
How does vortices affect Cl
Bigger the vortices the smaller the Cl
What can you do to a sweepback / highly tapered wing to prevent the tip stalling first in a
Washout
Change camber / thickness
What affect does a High wing load have on the induced drag
High wing load
More cl
Increased pressure differential
Bigger vortices
More induced drag
What are the 3 components of parasite drag
Form (pressure difference due to stagnation points)
Skin friction drag = friction between airflow and skin = boundary layer
Interference drag
What is the relationship between parasite drag and v^2
Parasite drag is proportional to v^2
What is the relationship between induced drag and v^2
Induced drag is inversely proportional to v^2
How do you reduce form drag
Streamline
When is skin friction greater
Rough skin caused by ice/ water / dirt / age
Colder air
Speed
Surface area
How do you reduce interference drag
Fillets (non structural fairings) to smooth out joints
What causes more parasite drag
“Dirty” aircraft
Landing gear
Flaps
Spoilers
How does AOA affect parasite drag
It doesn’t unless at very high AOA
What happens to cl when you double the airspeed
1/4 of original value
cause v^2 = 4x
Therefor cl needs to be divided by 4 to maintain the L
What happens to Cdi when you double airspeed
1/16th
Because Cdi is proportional to Cl^2
What happens to Di when speed is doubled
1/4 because Di is proportional to 1/v^2
What is the formula for Di to aspect ratio
Di is proportional to 1/ aspect ratio
What is the formula for Cdi and aspect ratio
Cdi is proportional to Cl^2/aspect ratio
How can u reduce induced drag
Modify wingtips makes it more difficult for adverse pressure gradient to push air round wing tip
How is induced drag created
Downwash and vortices
When do you spend the most time in the “unstable” zone
Landing
How does altitude affect the total drag curve if the x-axis plots TAS
More to the right
How does increased mass affect the drag curve
Up and to the right
How does being in a “dirty” configuration affect the drag curve
Up and to the left
What is the mean geometric chord of a wing
Wing area divided by the wing span
