NIFE AERO EXAM REVIEW
QUESTIONS WITH CORRECT
ANSWERS
Which is easier to reduce between friction and form drag - Answer-Form with a more
streamlined object
How to fix friction drag - Answer-Glossy, flat finish to surfaces, eliminating protruding
rivet heads, roughness, and other irregularities
Induced Drag, and what does it affect - Answer-Inherent when a wing is producing lift
and affects the vertical lift component counteracting weight
Talk about induced drag and lift with pressure - Answer-the pressure on the lower
surface of the wing is greater than on the upper surface, so the air tends to flow from
the high-pressure area below the wingtip upward to the low-pressure area above wing
as air curls up around wingtip, it combines with the wing's downwash to form a fast
spinning trailing vortex
Whenever the wing is producing lift, induced drag occurs and wingtip vortices are
created
What do wingtip vortices... - Answer-there is twice as much downwash as upwash near
the wingtips
Induced drag is which component of the total lift - Answer-Horizontal Component
Incresing AOA does what to two other things - Answer-Increase lift, increases inducted
drag
Induced Drag Equation - Answer-Di = (KL^2/pV^2b^2) = (KW^2/pV^2b^2)
Another way to reduce induced drag - Answer-install devices that impede spanwise
airflow around the wingtip (winglets, wingtip tanks, missile rails)
What makes up total drag curve - Answer-Parasite and Induced Drag added together
What is the lift/drag ratio - Answer-Used to determine the efficiency of an airfoil
(L/Dmax)
, Max L/D ratio is called... - Answer-L/Dmax, which is known as max range
Things to know about L/D max - Answer-L/Dmax AOA is located at the bottom of the
total drag curve (min total drag) (thus so is max range)
Most efficient AOA
The boundary layer is... - Answer-that layer of airflow over a surface that demonstrates
local airflow retardation due to viscosity
1mm thick at leading edge of airfoil, and grows in thickness
Laminar airflow - Answer-moves smoothly along in streamlines
little friction
easily separated from surface
Turbulent Flow - Answer-the streamlines break up and the flow is disorganized and
irregular.
high friction
adheres to surface better
Talk about airflow in boundary layers - Answer-air flows aft from leading edge (high
static pressure) towards point of max thickness (low static pressure) = favorable
pressure gradient
As air flows aft from the point of max thickness, toward trailing edge (higher static
pressure), encounters adverse pressure gradient
Adverse pressure gradient - Answer-strongest at high lift conditions and at high angles
of attack in particular
Stall - Answer-increase in AOA leads to decrease in Cl (beyond Clmax)
only cause is excessive AOA
stalls result in - Answer-decreased lift
increased drag,
altitude loss
Stall speed equation - Answer-know it
as airplane weight decreases, what happens to stall speed - Answer-decreases
QUESTIONS WITH CORRECT
ANSWERS
Which is easier to reduce between friction and form drag - Answer-Form with a more
streamlined object
How to fix friction drag - Answer-Glossy, flat finish to surfaces, eliminating protruding
rivet heads, roughness, and other irregularities
Induced Drag, and what does it affect - Answer-Inherent when a wing is producing lift
and affects the vertical lift component counteracting weight
Talk about induced drag and lift with pressure - Answer-the pressure on the lower
surface of the wing is greater than on the upper surface, so the air tends to flow from
the high-pressure area below the wingtip upward to the low-pressure area above wing
as air curls up around wingtip, it combines with the wing's downwash to form a fast
spinning trailing vortex
Whenever the wing is producing lift, induced drag occurs and wingtip vortices are
created
What do wingtip vortices... - Answer-there is twice as much downwash as upwash near
the wingtips
Induced drag is which component of the total lift - Answer-Horizontal Component
Incresing AOA does what to two other things - Answer-Increase lift, increases inducted
drag
Induced Drag Equation - Answer-Di = (KL^2/pV^2b^2) = (KW^2/pV^2b^2)
Another way to reduce induced drag - Answer-install devices that impede spanwise
airflow around the wingtip (winglets, wingtip tanks, missile rails)
What makes up total drag curve - Answer-Parasite and Induced Drag added together
What is the lift/drag ratio - Answer-Used to determine the efficiency of an airfoil
(L/Dmax)
, Max L/D ratio is called... - Answer-L/Dmax, which is known as max range
Things to know about L/D max - Answer-L/Dmax AOA is located at the bottom of the
total drag curve (min total drag) (thus so is max range)
Most efficient AOA
The boundary layer is... - Answer-that layer of airflow over a surface that demonstrates
local airflow retardation due to viscosity
1mm thick at leading edge of airfoil, and grows in thickness
Laminar airflow - Answer-moves smoothly along in streamlines
little friction
easily separated from surface
Turbulent Flow - Answer-the streamlines break up and the flow is disorganized and
irregular.
high friction
adheres to surface better
Talk about airflow in boundary layers - Answer-air flows aft from leading edge (high
static pressure) towards point of max thickness (low static pressure) = favorable
pressure gradient
As air flows aft from the point of max thickness, toward trailing edge (higher static
pressure), encounters adverse pressure gradient
Adverse pressure gradient - Answer-strongest at high lift conditions and at high angles
of attack in particular
Stall - Answer-increase in AOA leads to decrease in Cl (beyond Clmax)
only cause is excessive AOA
stalls result in - Answer-decreased lift
increased drag,
altitude loss
Stall speed equation - Answer-know it
as airplane weight decreases, what happens to stall speed - Answer-decreases
