Aero Ch. 2 | Questions with 100% Verified Answers | Latest
Update 2026/2027
Question: Explain the aerodynamic relationship of the four primary forces of equilibrium flight
Answer: Four primary forces of flight: Lift, Weight, Thrust and Drag Lift: the component of the aerodynamic
force acting perpendicular to the relative wind. Weight: the force at which a mass is attracted toward the
center of the earth by gravity Thrust: is the force produced by a jet engine or engine/propeller combination
Drag: the component of the aerodynamic force acting parallel to, and in the same direction as the relative
wind. Equilibrium flight: sum of all moments = ZERO
Question: Describe how the four forces of flight affect eachother
Answer: Lift counters weight, thrust counters drag.
Question: State the pressure distribution around an airfoil, given changes in camber
Answer: As air encounters the leading edge of the airfoil, it separates between the top and bottom of the
airfoil. On a positively cambered airfoil, the air traveling above the airfoil will increase in velocity, and
therefore, dynamic pressure (q). Because of an increase in (q), static pressure (Ps) decreases. Underneath the
airfoil, the air increases velocity, but increases in velocity less than the air above the airfoil. Therefore, the
static pressure (Ps) below the airfoil remains inequal to and higher than the static pressure (Ps) of the air above
the airfoil. Above the airfoil: dynamic pressure increases a lot, static pressure decreases a lot. H=Ps↓↓ + q↑↑
Below the airfoil: dynamic pressure increases slightly, static pressure decreases slightly. H=Ps↓ + q↑ Bernoulli
effect: Lower Ps (Top of airfoil) < Higher Ps (Bottom of airfoil) this produces lift
Question: State the pressure distribution around an airfoil, given changes in angle of attack
Answer: Above the airfoil: dynamic pressure increases a lot, static pressure decreases a lot. H=Ps↓↓ + q↑↑
Below the airfoil: dynamic pressure increases slightly, static pressure decreases slightly. H=Ps↓ + q↑ Above
airfoil Ps < below airfoil Ps = Lift Increasing the angle of attack (α) results in a continued reduction of the
cross-sectional area of the streamtube flowing over the top surface of an airfoil, resulting in more lift being
created. An increased AOA will continue to create more lift until the coefficient of lift maximum (CLmax) is
reached.
Question: Define lift component of aerodynamic force
Answer: Lift (L) is the component of the aerodynamic force acting perpendicular to the relative wind.
Question: Describe how factors in the lift equation affect lift production, given density, velocity, surface area,
and coefficient of lift
Answer: L = 1/2p * V^2 S CL L = lift p = density V = velocity S = surface area CL = coefficient of lift Increase in
density or velocity will increase lift. Increase in surface area will increase lift. Velocity and AOA (CL) are
inversely related in level flight.
Question: List the factors affecting coefficient of lift that the pilot can directly control
Answer: AOA is the most important and easiest for pilot to change. The shape of the airfoil can be controlled.
Velocity can be directly controlled.
Question: Define drag component of aerodynamic force
Answer: That component of the aerodynamic force acting parallel to, and in the same direction as the relative
wind. It acts as a retarding force.
, Question: Define parasite drag
Answer: Parasite Drag (Dp) is drag that is not associated with the production of lift. Dp=1/2ρV^2f Dp=Total
Parasite Drag ρ=Density V=Velocity f=Equivalent Parasite Area (the area of a flat plate perpendicular to the
relative wind that would produce the same amount of drag as form drag, friction drag and interference drag
combined. Not the cross-sectional area of the airplane)
Question: Define form drag How to reduce this drag
Answer: Drag resulting from airflow over a surface with some frontal area, often referred to as pressure drag,
profile drag, or plate drag. To reduce form drag, the fuselage and other surfaces exposed to the airstream are
streamlined (shaped like a teardrop).
Question: Friction drag How to reduce friction drag
Answer: Drag arising from friction forces at the surface of an aircraft, due to viscosity of the air. To reduce
friction drag, by smoothing the exposed surfaces of the airplane through painting, cleaning, waxing or
polishing.
Question: Interference drag How to reduce interference drag
Answer: Drag caused by the mixing of streamlines around aircraft components due to their proximity. This drag
can be minimized with proper fairing and filleting, which allows the streamlines to meet gradually rather than
abruptly. Total ID is higher than adding each individual drag.
Question: State the effects of upwash on an infinite wing
Answer: Relative wind on an infinite wing can only flow chordwise. High pressure air under the leading edge
attempts to equalize with the low pressure air above the wing. This results in some of the air that otherwise
would have passed under the wing flowing up and over the leading edge. This flow is called upwash. Upwash
increases lift because it increases the average angle of attack on the wing. Upwash exactly balances
downwash resulting in no net change in lift, on an infinite wing.
Question: State the effects of downwash on an infinite wing
Answer: Some of the air on top of the wing also flows down and under the trailing edge, which is downwash.
Downwash decreases lift by reducing the average angle of attack on the wing. Upwash exactly balances
downwash resulting in no net change in lift, on an infinite wing.
Question: State the effects of upwash on a finite wing
Answer: Upwash on a finite wing acts similar to upwash on an infinite wing. Some of this upwash also flows
around the wingtips, joining the downash and creating wingtip vortices. The downwash of a finite wing is
approximately double that of the upwash.
Question: State the effects of downwash on a finite wing
Answer: Some of the high pressure air in the leading edge stagnation point flows spanwise to the wingtips,
instead of chordwise over the wing. This airflow joins the air on the upper surface of the wing. There, it
combines with the chordwise flow that has produced lift and adds to the downwash. Downwash approximately
doubles by this process due to the spanwise flow moving around the wingtip, and also causes wingtip vortices.
Question: Define induced drag
Answer: That portion of total drag resulting from the production of lift.
Update 2026/2027
Question: Explain the aerodynamic relationship of the four primary forces of equilibrium flight
Answer: Four primary forces of flight: Lift, Weight, Thrust and Drag Lift: the component of the aerodynamic
force acting perpendicular to the relative wind. Weight: the force at which a mass is attracted toward the
center of the earth by gravity Thrust: is the force produced by a jet engine or engine/propeller combination
Drag: the component of the aerodynamic force acting parallel to, and in the same direction as the relative
wind. Equilibrium flight: sum of all moments = ZERO
Question: Describe how the four forces of flight affect eachother
Answer: Lift counters weight, thrust counters drag.
Question: State the pressure distribution around an airfoil, given changes in camber
Answer: As air encounters the leading edge of the airfoil, it separates between the top and bottom of the
airfoil. On a positively cambered airfoil, the air traveling above the airfoil will increase in velocity, and
therefore, dynamic pressure (q). Because of an increase in (q), static pressure (Ps) decreases. Underneath the
airfoil, the air increases velocity, but increases in velocity less than the air above the airfoil. Therefore, the
static pressure (Ps) below the airfoil remains inequal to and higher than the static pressure (Ps) of the air above
the airfoil. Above the airfoil: dynamic pressure increases a lot, static pressure decreases a lot. H=Ps↓↓ + q↑↑
Below the airfoil: dynamic pressure increases slightly, static pressure decreases slightly. H=Ps↓ + q↑ Bernoulli
effect: Lower Ps (Top of airfoil) < Higher Ps (Bottom of airfoil) this produces lift
Question: State the pressure distribution around an airfoil, given changes in angle of attack
Answer: Above the airfoil: dynamic pressure increases a lot, static pressure decreases a lot. H=Ps↓↓ + q↑↑
Below the airfoil: dynamic pressure increases slightly, static pressure decreases slightly. H=Ps↓ + q↑ Above
airfoil Ps < below airfoil Ps = Lift Increasing the angle of attack (α) results in a continued reduction of the
cross-sectional area of the streamtube flowing over the top surface of an airfoil, resulting in more lift being
created. An increased AOA will continue to create more lift until the coefficient of lift maximum (CLmax) is
reached.
Question: Define lift component of aerodynamic force
Answer: Lift (L) is the component of the aerodynamic force acting perpendicular to the relative wind.
Question: Describe how factors in the lift equation affect lift production, given density, velocity, surface area,
and coefficient of lift
Answer: L = 1/2p * V^2 S CL L = lift p = density V = velocity S = surface area CL = coefficient of lift Increase in
density or velocity will increase lift. Increase in surface area will increase lift. Velocity and AOA (CL) are
inversely related in level flight.
Question: List the factors affecting coefficient of lift that the pilot can directly control
Answer: AOA is the most important and easiest for pilot to change. The shape of the airfoil can be controlled.
Velocity can be directly controlled.
Question: Define drag component of aerodynamic force
Answer: That component of the aerodynamic force acting parallel to, and in the same direction as the relative
wind. It acts as a retarding force.
, Question: Define parasite drag
Answer: Parasite Drag (Dp) is drag that is not associated with the production of lift. Dp=1/2ρV^2f Dp=Total
Parasite Drag ρ=Density V=Velocity f=Equivalent Parasite Area (the area of a flat plate perpendicular to the
relative wind that would produce the same amount of drag as form drag, friction drag and interference drag
combined. Not the cross-sectional area of the airplane)
Question: Define form drag How to reduce this drag
Answer: Drag resulting from airflow over a surface with some frontal area, often referred to as pressure drag,
profile drag, or plate drag. To reduce form drag, the fuselage and other surfaces exposed to the airstream are
streamlined (shaped like a teardrop).
Question: Friction drag How to reduce friction drag
Answer: Drag arising from friction forces at the surface of an aircraft, due to viscosity of the air. To reduce
friction drag, by smoothing the exposed surfaces of the airplane through painting, cleaning, waxing or
polishing.
Question: Interference drag How to reduce interference drag
Answer: Drag caused by the mixing of streamlines around aircraft components due to their proximity. This drag
can be minimized with proper fairing and filleting, which allows the streamlines to meet gradually rather than
abruptly. Total ID is higher than adding each individual drag.
Question: State the effects of upwash on an infinite wing
Answer: Relative wind on an infinite wing can only flow chordwise. High pressure air under the leading edge
attempts to equalize with the low pressure air above the wing. This results in some of the air that otherwise
would have passed under the wing flowing up and over the leading edge. This flow is called upwash. Upwash
increases lift because it increases the average angle of attack on the wing. Upwash exactly balances
downwash resulting in no net change in lift, on an infinite wing.
Question: State the effects of downwash on an infinite wing
Answer: Some of the air on top of the wing also flows down and under the trailing edge, which is downwash.
Downwash decreases lift by reducing the average angle of attack on the wing. Upwash exactly balances
downwash resulting in no net change in lift, on an infinite wing.
Question: State the effects of upwash on a finite wing
Answer: Upwash on a finite wing acts similar to upwash on an infinite wing. Some of this upwash also flows
around the wingtips, joining the downash and creating wingtip vortices. The downwash of a finite wing is
approximately double that of the upwash.
Question: State the effects of downwash on a finite wing
Answer: Some of the high pressure air in the leading edge stagnation point flows spanwise to the wingtips,
instead of chordwise over the wing. This airflow joins the air on the upper surface of the wing. There, it
combines with the chordwise flow that has produced lift and adds to the downwash. Downwash approximately
doubles by this process due to the spanwise flow moving around the wingtip, and also causes wingtip vortices.
Question: Define induced drag
Answer: That portion of total drag resulting from the production of lift.
