NIFE - Aero Review Questions and Answers with
complete solution
What is density?
rho (ρ) - mass per unit of volume
What happens to density if you increase humidity?
Density decreases (inverse relationship)
What's a moment?
Rotational force around a point.
What is a moment arm?
Distance from the force.
How do you find the moment?
Force x Distance
What is static pressure?
The amount weight/air molecules above you.
What is the gas law?
P = ρRT
If pressure remains constant, and density goes up, what happens to
temperature?
It must go down (Gas Law: P = ρRT)
What four conditions are required for steady airflow?
Temperature, density, veolcity, and pressure must remain constant
Describe the 5 airspeeds
ICETG: Instrument Air Speed, Calibrated Air Speed, Equivalent Air Speed, True Air
Speed, and Ground Speed
How does the plane determine instrument air speed?
Pito tube measures total pressure. Static air ports measure static pressure. Dynamic
Pressure = Total - Static --> convert to knots
How is calibrated air speed calculated?
Indicated air speed adjusted for instrument error
How is equivalent air speed calculated?
Calibarated air speed adjusted for compressibility
How is true air speed calculated?
Equivalent air speed adjusted for density
What is true air speed?
The speed at which the airplane is traveling through the air mass
How is ground speed calculated?
True air speed adjusted for wind
How does a headwind affect ground speed?
Slower than true air speed
How does a tail wind affect ground speed?
Faster than true air speed
At a constant indicated air speed, you are flying at 5,000 ft with a 10kt
headwind. You climb to 10,000ft again with a 10kt head wind. What will happen
to ground speed?
It will increase because the true air speed increases (density is going down, but
indicated air speed is staying the same)
What is the mean camber line?
, Locus of ponts halfway between the upper and lower surface of the wing
What is the chord line?
Straight line from leading edge to trailing edge of the wing
How do you determine the camber of an airfoil?
Positive: mean camber line above the chord line. Symmetrical - MCL at the chord
line.Negative: MCL below the chordline.
What is the variable b?
Wingspan (tip to tip). Used in induced drag equation (denomenator). Longer
wingspan = less induced drag
What are the two kinds of airflow around the wing?
Chordwise (perpendicular to leading edge, creates lift); spanwise (paralell to the
leading edge, deosn't create lift)
What is relative wind?
Airflow the aircraft experiences going through the air mass. Equal and opposite to
the flight path.
What is the flight path?
The path that the center of gravity moves through the air mass
What is the angle of attack?
The angle between the Relative Wind and the chordline.
What is the angle of attack largely dependent on?
Flight path. (The same pitch attitude can have vastly different AOA depdent on the
flight path)
What are the three axes of movement?
Longitudinal, Lateral, and Vertical
What is movement about the longitudinal axis called? What is the controlling
surface?
Roll, ailerons
What is movement about the lateral axis called? What is the controlling
surface?
Pitch, elevator
What is movement about the vertical axis called? What is the controlling
surface?
Yaw, rudder
What is the name for the point where all aerodynamic forces are pointing?
Aerodynamic Center (aka point of maximum thickness, quarter chord)
In what direction does lift act?
Perpendicular to relative wind
In what direction does drag act?
Same direction and parallel to relative wind
Describe the journey of a particle of air around an airfoil in a streamtube.
Steady airflow hits airfoil (leading edge stagnation point). Very high pressure. If
particle goes over the airfoil, the particle increases in speed (continuity equation), so
static pressure goes down (Bernouli's eq) - lowest pressure (and highest velocity) is
at the aerodynamic center/quarter chord. Then, as it travels down the back side of
the wing the velocity decreases. Underneath, the same process similarly happens
but to a lesser extent, so there is small-to-medium pressure below the wing. This
relative increase in pressure pushes the wing up (lift).
What is the lift equation?
Lift = 1/2rhoV^2SCl
What is included in the coefficient of lift?
complete solution
What is density?
rho (ρ) - mass per unit of volume
What happens to density if you increase humidity?
Density decreases (inverse relationship)
What's a moment?
Rotational force around a point.
What is a moment arm?
Distance from the force.
How do you find the moment?
Force x Distance
What is static pressure?
The amount weight/air molecules above you.
What is the gas law?
P = ρRT
If pressure remains constant, and density goes up, what happens to
temperature?
It must go down (Gas Law: P = ρRT)
What four conditions are required for steady airflow?
Temperature, density, veolcity, and pressure must remain constant
Describe the 5 airspeeds
ICETG: Instrument Air Speed, Calibrated Air Speed, Equivalent Air Speed, True Air
Speed, and Ground Speed
How does the plane determine instrument air speed?
Pito tube measures total pressure. Static air ports measure static pressure. Dynamic
Pressure = Total - Static --> convert to knots
How is calibrated air speed calculated?
Indicated air speed adjusted for instrument error
How is equivalent air speed calculated?
Calibarated air speed adjusted for compressibility
How is true air speed calculated?
Equivalent air speed adjusted for density
What is true air speed?
The speed at which the airplane is traveling through the air mass
How is ground speed calculated?
True air speed adjusted for wind
How does a headwind affect ground speed?
Slower than true air speed
How does a tail wind affect ground speed?
Faster than true air speed
At a constant indicated air speed, you are flying at 5,000 ft with a 10kt
headwind. You climb to 10,000ft again with a 10kt head wind. What will happen
to ground speed?
It will increase because the true air speed increases (density is going down, but
indicated air speed is staying the same)
What is the mean camber line?
, Locus of ponts halfway between the upper and lower surface of the wing
What is the chord line?
Straight line from leading edge to trailing edge of the wing
How do you determine the camber of an airfoil?
Positive: mean camber line above the chord line. Symmetrical - MCL at the chord
line.Negative: MCL below the chordline.
What is the variable b?
Wingspan (tip to tip). Used in induced drag equation (denomenator). Longer
wingspan = less induced drag
What are the two kinds of airflow around the wing?
Chordwise (perpendicular to leading edge, creates lift); spanwise (paralell to the
leading edge, deosn't create lift)
What is relative wind?
Airflow the aircraft experiences going through the air mass. Equal and opposite to
the flight path.
What is the flight path?
The path that the center of gravity moves through the air mass
What is the angle of attack?
The angle between the Relative Wind and the chordline.
What is the angle of attack largely dependent on?
Flight path. (The same pitch attitude can have vastly different AOA depdent on the
flight path)
What are the three axes of movement?
Longitudinal, Lateral, and Vertical
What is movement about the longitudinal axis called? What is the controlling
surface?
Roll, ailerons
What is movement about the lateral axis called? What is the controlling
surface?
Pitch, elevator
What is movement about the vertical axis called? What is the controlling
surface?
Yaw, rudder
What is the name for the point where all aerodynamic forces are pointing?
Aerodynamic Center (aka point of maximum thickness, quarter chord)
In what direction does lift act?
Perpendicular to relative wind
In what direction does drag act?
Same direction and parallel to relative wind
Describe the journey of a particle of air around an airfoil in a streamtube.
Steady airflow hits airfoil (leading edge stagnation point). Very high pressure. If
particle goes over the airfoil, the particle increases in speed (continuity equation), so
static pressure goes down (Bernouli's eq) - lowest pressure (and highest velocity) is
at the aerodynamic center/quarter chord. Then, as it travels down the back side of
the wing the velocity decreases. Underneath, the same process similarly happens
but to a lesser extent, so there is small-to-medium pressure below the wing. This
relative increase in pressure pushes the wing up (lift).
What is the lift equation?
Lift = 1/2rhoV^2SCl
What is included in the coefficient of lift?
