# Aerodynamics Questions and Answers – Modern Low Speed Airfoils – 2

This set of Aerodynamics Question Bank focuses on “Modern Low Speed Airfoils – 2”.

1. Is NASA designed low speed airfoils?
a) True
b) False
View Answer

Answer: a
Explanation: During 1970s, NASA designed a series of low-speed airfoils that have performance superior to the earlier NACA airfoils. The standard NACA airfoils were based almost exclusively on experimental data obtained during 1930s and 1940s.

2. Is NASA airfoil designed using numerical technique?
a) False
b) True
View Answer

Answer: b
Explanation: The new NASA airfoils were designed on a computer using a numerical technique similar to the source and vortex panel methods discussed earlier, along with numerical predictions of the viscous flow behavior.

3. Is wind tunnel test is conducted to verify the computer designed profiles?
a) True
b) False
View Answer

Answer: a
Explanation: Wind tunnel tests were then conducted to verify the computer designed profiles and to obtain the definitive airfoil properties, out of this work first came the general aviation whit comb airfoil. Which has since been predesignated the LS-0417 airfoil.
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4. What is the leading edge radius of LS-0417 airfoil?
a) 0.07c
b) 0.05c
c) 0.08c
d) 0.09c
View Answer

Answer: c
Explanation: LS-0417 airfoil has a leading edge radius of 0.08c in comparison to the standard 0.02c in order to flatten the usual peak in pressure coefficient near the nose, also that the bottom surface near the trailing edge is cusped in order to increase the camber.

5. Is flow separation over the top surface of the airfoil at high angle of attack?
a) True
b) False
View Answer

Answer: a
Explanation: The flow separation over the top surface at a high angle of attack, hence yielding higher values of the maximum lift coefficient. The lift and moment properties are compared with the NAC 2412 airfoil.
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6. Is 17% is the thickness of NASA LS-0417 airfoil?
a) True
b) False
View Answer

Answer: a
Explanation: The NASA LS- 0417 airfoil has a maximum thickness of 17% and a design lift coefficient of 0.4. Using the same camber line, NASA has extended this airfoil into a family of a low-speed airfoil of different thickness for example LS-0409 and the LS-0413.

7. Is a 50% increase in the ratio of lift to drag at a lift coefficient?
a) True
b) False
View Answer

Answer: a
Explanation: A 50 percent increase in the ratio of lift to drag at a lift coefficient of 0.1. This value of q=0.1 is typical of the climb lift coefficient for general aviation aircraft, and a high value of L/D greatly improves the climb.
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8. Is super critical airfoil used to improve the drag at subsonic speed?
a) True
b) False
View Answer

Answer: a
Explanation: The super critical airfoil was a major breakthrough in high speed aerodynamics, the super critical airfoil is used to improve the drag at subsonic speeds. The LS-0417 low speed airfoil first introduced as the GA-1 airfoil.

9. Is initial distribution is given by solid curves?
a) True
b) False
View Answer

Answer: a
Explanation: The optimization technique is iterative and requires starting with a pressure distribution that is not the desired, specified one, the initial distribution is given by the solid curves and the airfoil shapes appears distorted because an expanded scale is used for the ordinate.
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10. Is pressure coefficient distributions are calculated for flow over an airfoil?
a) True
b) False
View Answer

Answer: a
Explanation: The unstructured mesh for the numerical calculation of the flow over an airfoil to calculate for pressure coefficient distributions, airfoil shapes that support the specified pressure distribution is obtained, as given by the circle. The initial airfoil shape is also shown in constant scale.

Sanfoundry Global Education & Learning Series – Aerodynamics.

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