Mathematical Problems on Wind Tunnel Testing for Aircraft
Aerodynamics
1. If a wind tunnel has a test section area of 4 m² and an airflow velocity of 100 m/s, what is the
volume flow rate?
A) 200 m³/s B) 300 m³/s C) 400 m³/s D) 500 m³/s
Answer: C) 400 m³/s
2. A 1:10 scale aircraft model is tested in a wind tunnel. If the full-scale aircraft flies at 250 m/s, what
should be the wind tunnel airspeed to maintain dynamic similarity?
A) 25 m/s B) 79.1 m/s C) 250 m/s D) 790.6 m/s
Answer: B) 79.1 m/s
3. The drag force on an aircraft model in a wind tunnel is measured to be 50 N at a dynamic pressure
of 2500 Pa. What is the drag coefficient if the model's reference area is 0.5 m²?
A) 0.02 B) 0.04 C) 0.06 D) 0.08
Answer: B) 0.04
4. A wind tunnel fan has a power rating of 500 kW and an efficiency of 85%. If the air density is 1.2
kg/m³ and the test section area is 5 m², what is the maximum achievable airspeed?
A) 93.5 m/s B) 102.1 m/s C) 110.7 m/s D) 119.3 m/s
Answer: C) 110.7 m/s
5. If the Reynolds number in a wind tunnel test is 2 × 10⁶ and the characteristic length of the model is
1 m, what is the kinematic viscosity of the air if the flow velocity is 50 m/s?
A) 1.5 × 10⁻⁵ m²/s B) 2.5 × 10⁻⁵ m²/s C) 3.5 × 10⁻⁵ m²/s D) 4.5 × 10⁻⁵ m²/s
Answer: B) 2.5 × 10⁻⁵ m²/s
6. A wind tunnel has a contraction ratio of 9:1. If the test section has a cross-sectional area of 3 m²,
what is the area of the settling chamber?
A) 18 m² B) 21 m² C) 24 m² D) 27 m²
Answer: D) 27 m²
7. The lift force on an aircraft wing model is measured to be 1000 N at an angle of attack of 5°. If the
dynamic pressure is 3000 Pa and the wing area is 2 m², what is the lift coefficient?
A) 0.125 B) 0.167 C) 0.208 D) 0.250
Answer: B) 0.167
8. A wind tunnel operates at a Mach number of 0.8. If the speed of sound in the tunnel is 340 m/s,
what is the flow velocity?
A) 238 m/s B) 272 m/s C) 306 m/s D) 340 m/s
Answer: B) 272 m/s
9. The moment coefficient of an aircraft model is found to be 0.05 at a dynamic pressure of 2000 Pa.
If the reference area is 0.4 m² and the mean aerodynamic chord is 0.2 m, what is the pitching
moment?
A) 0.8 Nm B) 1.6 Nm C) 2.4 Nm D) 3.2 Nm
Answer: A) 0.8 Nm
10. A wind tunnel has a test section of 2 m × 2 m. If the maximum allowable blockage ratio is 5%,
what is the maximum frontal area of a model that can be tested?
A) 0.1 m² B) 0.15 m² C) 0.2 m² D) 0.25 m²
Answer: C) 0.2 m²
11. If the pressure difference between the settling chamber and the test section of a wind tunnel is
5000 Pa, and the air density is 1.2 kg/m³, what is the velocity in the test section?
A) 81.6 m/s B) 91.3 m/s C) 101.0 m/s D) 110.7 m/s
Answer: B) 91.3 m/s
12. A 1:20 scale aircraft model is tested in a wind tunnel at 50 m/s. What should be the full-scale
aircraft's speed to maintain the same Reynolds number if the kinematic viscosity remains constant?
A) 2.5 m/s B) 10 m/s C) 25 m/s D) 50 m/s
Answer: A) 2.5 m/s
13. The power required to overcome drag in a wind tunnel test is 10 kW. If the flow velocity is 100
m/s, what is the drag force on the model?
A) 50 N B) 100 N C) 150 N D) 200 N
Answer: B) 100 N
14. A wind tunnel operates at a dynamic pressure of 5000 Pa. If the air density is 1.1 kg/m³, what is
the flow velocity?
A) 85.7 m/s B) 90.5 m/s C) 95.3 m/s D) 100.1 m/s
Answer: C) 95.3 m/s
15. The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
The lift-to-drag ratio of an aircraft model is measured to be 15 at an angle of attack of 3°. If the lift
coefficient is 0.6, what is the drag coefficient?
A) 0.02 B) 0.03 C) 0.04 D) 0.05
Answer: C) 0.04
16. A wind tunnel has a test section area of 6 m² and operates at a Mach number of 0.5. If the
stagnation pressure is 150 kPa and the stagnation temperature is 300 K, what is the mass flow rate?
(Assume γ = 1.4 for air)
A) 173.2 kg/s B) 183.2 kg/s C) 193.2 kg/s D) 203.2 kg/s
Answer: C) 193.2 kg/s
17. The boundary layer thickness on a flat plate model in a wind tunnel is measured to be 5 mm at a
distance of 0.5 m from the leading edge. If the flow follows a 1/7th power law velocity profile, what
is the displacement thickness?
A) 0.56 mm B) 0.63 mm C) 0.71 mm D) 0.78 mm
Answer: B) 0.63 mm
18. A wind tunnel force balance measures normal and axial forces of 1000 N and 200 N respectively
on an aircraft model at an angle of attack of 10°. What is the lift force?
A) 962.3 N B) 984.8 N C) 1007.3 N D) 1029.8 N
Answer: B) 984.8 N
19. The static pressure in a wind tunnel test section is measured to be 90 kPa, while the total
pressure is 110 kPa. If the air density is 1.1 kg/m³, what is the flow velocity?
A) 134.8 m/s B) 144.8 m/s C) 154.8 m/s D) 164.8 m/s
Answer: C) 154.8 m/s
20. A cylindrical pressure vessel in a wind tunnel has a diameter of 0.1 m and a length of 0.5 m. If the
pressure coefficient at a point on its surface is -0.5 and the dynamic pressure is 2000 Pa, what is the
local static pressure if the freestream static pressure is 100 kPa?
A) 99 kPa B) 98 kPa C) 97 kPa D) 96 kPa
Answer: A) 99 kPa
21. The temperature in a wind tunnel drops from 300 K in the settling chamber to 280 K in the test
section. What is the Mach number in the test section? (Assume γ = 1.4 for air)
A) 0.42 B) 0.52 C) 0.62 D) 0.72
Answer: C) 0.62
22. A wind tunnel operates at a Reynolds number of 5 × 10⁶ based on a model's chord length of 0.5
m. If the air density is 1.2 kg/m³ and the dynamic viscosity is 1.8 × 10⁻⁵ Pa·s, what is the flow
velocity?
A) 45 m/s B) 55 m/s C) 65 m/s D) 75 m/s
Answer: D) 75 m/s
23. The wake behind an airfoil model in a wind tunnel is measured to have a velocity deficit of 10% of
the freestream velocity. If the freestream velocity is 100 m/s and the wake width is 0.05 m, what is
the approximate profile drag coefficient for a wing with a 1 m span?
A) 0.0025 B) 0.0050 C) 0.0075 D) 0.0100
Answer: B) 0.0050
24. A wind tunnel has a test section of 3 m × 2 m and operates at a dynamic pressure of 3000 Pa. If a
model experiences a drag force of 150 N, what is its drag area?
A) 0.025 m² B) 0.050 m² C) 0.075 m² D) 0.100 m²
Answer: B) 0.050 m²
25. The pressure coefficient at the stagnation point of a body in subsonic flow is measured to be
1.03. What is the approximate Mach number of the flow? (Assume γ = 1.4 for air)
A) 0.20 B) 0.24 C) 0.28 D) 0.32
Answer: B) 0.24
26. A wind tunnel fan has a diameter of 2 m and rotates at 1800 RPM. If the flow coefficient is 0.6,
what is the volume flow rate?
A) 113.1 m³/s B) 169.6 m³/s C) 226.2 m³/s D) 282.7 m³/s
Answer: C) 226.2 m³/s
27. The boundary layer on a flat plate model transitions from laminar to turbulent at a Reynolds
number of 5 × 10⁵. If the flow velocity is 50 m/s and the kinematic viscosity is 1.5 × 10⁻⁵ m²/s, at what
distance from the leading edge does transition occur?
A) 0.10 m B) 0.15 m C) 0.20 m D) 0.25 m
Answer: B) 0.15 m
28. A wind tunnel operates at a Mach number of 2.5. If the stagnation temperature is 400 K, what is
the static temperature in the test section? (Assume γ = 1.4 for air)
A) 171.4 K B) 191.4 K C) 211.4 K D) 231.4 K
Answer: B) 191.4 K
29. The lift curve slope of an aircraft model is measured to be 5.2 per radian. If the aspect ratio of the
model is 6, what is the theoretical 3D lift curve slope according to lifting line theory?
A) 3.8 per radian B) 4.2 per radian C) 4.6 per radian D) 5.0 per radian
Answer: C) 4.6 per radian
30. A pitot-static tube in a wind tunnel measures a dynamic pressure of 4000 Pa. If the air density is
1.1 kg/m³, what is the flow velocity?
A) 75.8 m/s B) 85.2 m/s C) 94.6 m/s D) 104.0 m/s
Answer: B) 85.2 m/s
31. The moment coefficient of an aircraft model changes by 0.02 for a 1° change in angle of attack. If
the reference area is 0.5 m² and the mean aerodynamic chord is 0.25 m, what is the static margin at
a dynamic pressure of 2500 Pa?
A) 0.05 B) 0.10 C) 0.15 D) 0.20
Answer: B) 0.10
32. A wind tunnel has a contraction ratio of 12:1. If the velocity in the settling chamber is 5 m/s, what
is the velocity in the test section?
A) 45 m/s B) 50 m/s C) 55 m/s D) 60 m/s
Answer: D) 60 m/s
33. The skin friction coefficient on a flat plate model is measured to be 0.003. If the Reynolds number
based on plate length is 10⁷, what is the equivalent sand grain roughness height according to the
Nikuradse correlation?
A) 50 μm B) 100 μm C) 150 μm D) 200 μm
Answer: C) 150 μm
34. A wind tunnel operates at a Mach number of 1.5 and a stagnation pressure of 200 kPa. What is
the static pressure in the test section? (Assume γ = 1.4 for air)
A) 51.1 kPa B) 61.1 kPa C) 71.1 kPa D) 81.1 kPa
Answer: B) 61.1 kPa
35. The induced drag factor of a wing model is measured to be 0.05. If the aspect ratio of the wing is
8, what is the Oswald efficiency factor?
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
36. A wind tunnel force balance has a resolution of 0.1 N. If the dynamic pressure is 3000 Pa and the
model reference area is 0.4 m², what is the minimum detectable change in force coefficient?
A) 0.00083 B) 0.00167 C) 0.00250 D) 0.00333
Answer: A) 0.00083
37. The pressure ratio across a normal shock in a supersonic wind tunnel is measured to be 2.82.
What is the upstream Mach number? (Assume γ = 1.4 for air)
A) 1.6 B) 1.8 C) 2.0 D) 2.2
Answer: B) 1.8
38. A wind tunnel test section has a cross-sectional area of 4 m². If the mass flow rate is 400 kg/s and
the static temperature is 250 K, what is the Mach number? (Assume R = 287 J/(kg·K) for air)
A) 0.65 B) 0.75 C) 0.85 D) 0.95
Answer: C) 0.85
39. The pressure coefficient at the suction peak of an airfoil is measured to be -3.5 at a freestream
Mach number of 0.6. What is the local Mach number at this point? (Assume γ = 1
