What is the thickness in NACA 747A315 airfoil?

15%

25%

30%

Correct Answer : 15%

Explanation : In NACA 747A315 airfoil. The 7 denotes the series, 4 provides the location of minimum pressure on the upper surface in a tenth of chord, 7 provides the location of the minimum pressure on the lower surface in tenth of chord, the 4th character i.e. A indicates the thickness distribution and mean line form used. Again 5th digit 3 indicates the design lift coefficient in the tenth and the final two digits indicate the thickness of the chord 15%.

Recently Updated in Aerodynamics Questions

Is laminar flow is used to increase the drag and reduce the lift?

True

False

Can Not Say

None of the above

Correct Answer : Option (A) : True

Explanation : The effect can also be exploited by devices such as aerodynamic spoilers on aircraft, which deliberately spoil the laminar flow to increase the drag and reduce the lift on the aircraft, which also used as a break to stop the aircraft

Example of turbulent flow?

Laminar flow

Flow on a symmetric airfoil

Smoking rises from cigarette

Turbulent flow on the airfoil

Correct Answer : Option (C) : Smoking rises from cigarette

Explanation : Smoke rising from a cigarette is mostly turbulent flow. However, for the first few centimeters, the flow is laminar. The smoke plume becomes turbulent as its Reynolds number increases, due to its flow velocity and the characteristic length.

Is lift is generated due to large pressure gradients on the upper side of the airfoil?

True

False

Can Not Say

None of the above

Correct Answer : Option (A) : True

Explanation : At higher angles, very large adverse pressure gradients that develop on the upper side as the airfoil attempts to generate more lift causes the boundary layer to separate, leading to a major disruption of the flow over the airfoil and the wing stalls.