AVIA 305: Advanced Aerodynamics
Final Examination – 2026 Update
1. At hypersonic speeds, the aerodynamic center of a conventional airfoil shifts forward due to the
dominance of Newtonian flow theory.
Answer: True
Rationale: In hypersonic flow (M > 5), Newtonian impact theory becomes dominant. The
pressure coefficient CpCp is proportional to sin2θsin2θ, which effectively shifts the center of
pressure forward compared to supersonic linear theory.
2. Induced drag decreases proportionally with the square of the airspeed.
Answer: False
Rationale: Induced drag (DiDi) is inversely proportional to the square of the true airspeed (TAS).
As speed increases, induced drag decreases; however, it is parasitic drag that increases with the
square of the speed.
3. A wing with a negative twist (washout) experiences a root stall before the tip.
Answer: True
Rationale: Washout reduces the angle of attack at the wingtip. This ensures the root reaches
critical angle of attack first, maintaining aileron effectiveness during stall recovery.
4. In supersonic flow, increasing the sweep angle of a wing delays the formation of oblique shock waves.
Answer: False
, Rationale: Sweep delays the normal component of the Mach number (MnMn). It does not delay
the formation of shocks; rather, it reduces the strength of the shock by exposing the wing to a
lower effective Mach number relative to the leading edge.
5. The critical Mach number (McritMcrit) is the free-stream Mach number at which the first point of
supersonic flow appears on the airframe.
Answer: True
Rationale: McritMcrit is the threshold where local airflow reaches Mach 1.0, typically on the
upper surface of the wing, marking the onset of transonic effects.
6. Laminar flow airfoils are most effective in high-turbulence, low-Reynolds number environments
typical of UAVs.
Answer: False
Rationale: Laminar flow airfoils require extremely smooth surfaces and a laminar boundary
layer to achieve low drag. High turbulence (high Reynolds number) tends to trip the boundary
layer to turbulent prematurely, negating their advantage.
7. The Prandtl-Glauert singularity predicts infinite pressure coefficient at Mach 1.0.
Answer: True
Rationale: The Prandtl-Glauert rule includes a factor 1−M21−M2 in the denominator.
As M→1M→1, the factor approaches zero, theoretically leading to infinite pressure coefficients,
which explains the "sound barrier" concept.
8. Wingtip vortices are strongest during takeoff and landing phases due to high angle of attack and low
airspeed.
Answer: True
Rationale: Induced drag (and thus vortex strength) is proportional to the coefficient of lift
squared (CL2CL2) and inversely proportional to airspeed. High CLCL (takeoff/landing) and low
speed maximize vortex strength.
9. A higher aspect ratio always results in lower total drag for an aircraft.
Answer: False
Rationale: While a higher aspect ratio reduces induced drag, it increases parasitic drag (due to
increased structural weight and wetted area) and may lead to structural bending issues. There is
an optimum aspect ratio for a given design mission.
, 10. In a supercritical airfoil, the shock wave is positioned further aft and is weaker compared to a
conventional airfoil.
Answer: True
Rationale: Supercritical airfoils are designed with a flattened upper surface to delay shock
formation and position the shock aft, reducing wave drag and delaying the drag divergence
Mach number.
11. Adverse yaw occurs because the downgoing aileron produces more induced drag than the upgoing
aileron.
Answer: True
Rationale: The downgoing aileron increases camber and lift on that wingtip, increasing induced
drag, which yaws the nose toward the rising wing (opposite the desired roll direction).
12. Dynamic pressure (qq) is a function of density and velocity squared, independent of altitude.
Answer: False
Rationale: Dynamic pressure q=12ρV2q=21ρV2. Density (ρρ) changes significantly with altitude;
therefore, the same TAS yields different dynamic pressures at different altitudes.
13. The "Area Rule" (transonic) states that to reduce drag, the cross-sectional area of the aircraft must
change gradually, like a Sears-Haack body.
Answer: True
Rationale: Richard Whitcomb's Area Rule dictates that the longitudinal distribution of cross-
sectional area should be smooth to minimize wave drag in the transonic regime, leading to
"coke-bottle" fuselage designs.
14. Swept wings are inherently more stable in the stall than straight wings.
Answer: False
Rationale: Swept wings are prone to tip stalls because the boundary layer migrates spanwise
toward the tip due to spanwise flow, causing the tip to stall first, leading to pitch-up moments.
15. Circulation (ΓΓ) is directly proportional to the lift generated by an airfoil according to the Kutta-
Joukowski theorem.
Answer: True
Final Examination – 2026 Update
1. At hypersonic speeds, the aerodynamic center of a conventional airfoil shifts forward due to the
dominance of Newtonian flow theory.
Answer: True
Rationale: In hypersonic flow (M > 5), Newtonian impact theory becomes dominant. The
pressure coefficient CpCp is proportional to sin2θsin2θ, which effectively shifts the center of
pressure forward compared to supersonic linear theory.
2. Induced drag decreases proportionally with the square of the airspeed.
Answer: False
Rationale: Induced drag (DiDi) is inversely proportional to the square of the true airspeed (TAS).
As speed increases, induced drag decreases; however, it is parasitic drag that increases with the
square of the speed.
3. A wing with a negative twist (washout) experiences a root stall before the tip.
Answer: True
Rationale: Washout reduces the angle of attack at the wingtip. This ensures the root reaches
critical angle of attack first, maintaining aileron effectiveness during stall recovery.
4. In supersonic flow, increasing the sweep angle of a wing delays the formation of oblique shock waves.
Answer: False
, Rationale: Sweep delays the normal component of the Mach number (MnMn). It does not delay
the formation of shocks; rather, it reduces the strength of the shock by exposing the wing to a
lower effective Mach number relative to the leading edge.
5. The critical Mach number (McritMcrit) is the free-stream Mach number at which the first point of
supersonic flow appears on the airframe.
Answer: True
Rationale: McritMcrit is the threshold where local airflow reaches Mach 1.0, typically on the
upper surface of the wing, marking the onset of transonic effects.
6. Laminar flow airfoils are most effective in high-turbulence, low-Reynolds number environments
typical of UAVs.
Answer: False
Rationale: Laminar flow airfoils require extremely smooth surfaces and a laminar boundary
layer to achieve low drag. High turbulence (high Reynolds number) tends to trip the boundary
layer to turbulent prematurely, negating their advantage.
7. The Prandtl-Glauert singularity predicts infinite pressure coefficient at Mach 1.0.
Answer: True
Rationale: The Prandtl-Glauert rule includes a factor 1−M21−M2 in the denominator.
As M→1M→1, the factor approaches zero, theoretically leading to infinite pressure coefficients,
which explains the "sound barrier" concept.
8. Wingtip vortices are strongest during takeoff and landing phases due to high angle of attack and low
airspeed.
Answer: True
Rationale: Induced drag (and thus vortex strength) is proportional to the coefficient of lift
squared (CL2CL2) and inversely proportional to airspeed. High CLCL (takeoff/landing) and low
speed maximize vortex strength.
9. A higher aspect ratio always results in lower total drag for an aircraft.
Answer: False
Rationale: While a higher aspect ratio reduces induced drag, it increases parasitic drag (due to
increased structural weight and wetted area) and may lead to structural bending issues. There is
an optimum aspect ratio for a given design mission.
, 10. In a supercritical airfoil, the shock wave is positioned further aft and is weaker compared to a
conventional airfoil.
Answer: True
Rationale: Supercritical airfoils are designed with a flattened upper surface to delay shock
formation and position the shock aft, reducing wave drag and delaying the drag divergence
Mach number.
11. Adverse yaw occurs because the downgoing aileron produces more induced drag than the upgoing
aileron.
Answer: True
Rationale: The downgoing aileron increases camber and lift on that wingtip, increasing induced
drag, which yaws the nose toward the rising wing (opposite the desired roll direction).
12. Dynamic pressure (qq) is a function of density and velocity squared, independent of altitude.
Answer: False
Rationale: Dynamic pressure q=12ρV2q=21ρV2. Density (ρρ) changes significantly with altitude;
therefore, the same TAS yields different dynamic pressures at different altitudes.
13. The "Area Rule" (transonic) states that to reduce drag, the cross-sectional area of the aircraft must
change gradually, like a Sears-Haack body.
Answer: True
Rationale: Richard Whitcomb's Area Rule dictates that the longitudinal distribution of cross-
sectional area should be smooth to minimize wave drag in the transonic regime, leading to
"coke-bottle" fuselage designs.
14. Swept wings are inherently more stable in the stall than straight wings.
Answer: False
Rationale: Swept wings are prone to tip stalls because the boundary layer migrates spanwise
toward the tip due to spanwise flow, causing the tip to stall first, leading to pitch-up moments.
15. Circulation (ΓΓ) is directly proportional to the lift generated by an airfoil according to the Kutta-
Joukowski theorem.
Answer: True
