Flaps in Aviation

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Questions and Answers

What is the primary cause of form drag?

Frictional shear stress integrated over the surface

Mutual interaction of flow fields around each component

Lift generation

Separated air flow (correct)

If the indicated air speed is tripled, what will be the effect on parasite drag?

It will be increased by a factor of nine (correct)

It will remain the same

It will be reduced by half

It will be reduced to one ninth of its original value

What type of drag is associated with the generation of lift?

Zero-lift drag

Induced drag (correct)

Parasite drag

Wave drag

What is the sum of skin friction drag and form drag?

Profile drag Signup and view all the answers

What type of drag exists when the airplane is at zero lift angle of attack?

Zero-lift drag Signup and view all the answers

What is the primary factor that affects the frontal area presented to the airflow?

Airplane configuration Signup and view all the answers

What is the primary reason for the decrease in induced drag with an increase in aircraft speed?

The rearward inclination of the lift force decreases Signup and view all the answers

Why does induced drag decrease with an increase in aspect ratio for a given lift force?

The rearward inclination of the lift force is less, resulting in less drag Signup and view all the answers

What is the primary purpose of wing end plates in reducing induced drag?

To restrict the tip vortices and reduce downwash Signup and view all the answers

What is the effect of tip tanks on the wing bending moment?

It decreases the wing bending moment Signup and view all the answers

What is the primary reason for the increase in parasite drag coefficient due to airframe contamination?

Increase in surface roughness Signup and view all the answers

What is the direction of air movement around the airfoil tips?

From high pressure toward low pressure Signup and view all the answers

What is the relationship between lift and weight in certain maneuvers?

Lift is always greater than weight Signup and view all the answers

What is the effect of airfoil's tips vortex on the wing's performance?

It reduces the lift and increases the drag Signup and view all the answers

What is the effect of increasing weight on induced drag?

It increases induced drag Signup and view all the answers

What is the relationship between the Indicated Air Speed (IAS) and the Angle of Attack (𝛼) with respect to induced drag?

Lower IAS results in higher 𝛼 and greater induced drag Signup and view all the answers

What is the primary purpose of employing de-icing and anti-icing devices on airframes?

To reduce the parasite drag coefficient Signup and view all the answers

What is the term used to describe the whirlpool of air formed at the airfoil tips?

Vortex Signup and view all the answers

What happens to the flow if the turbulence intensity is large enough?

It triggers unfavourable transition and changes the behaviour of boundary layer. Signup and view all the answers

What can alter the effective Reynolds number in turbulent flow?

Free stream turbulence Signup and view all the answers

What is the primary research tool for studying turbulent air/gas flow?

Hot-Wire Anemometry (HWA) Signup and view all the answers

What happens to the flow angularity in high turbulence levels?

It becomes distorted Signup and view all the answers

Why can wind tunnels with identical levels of turbulence produce different test results?

Due to differences in their turbulence spectra. Signup and view all the answers

What can turbulence excite in turbulent flow?

Local Mach number Signup and view all the answers

What is the primary reason for maintaining a long contraction length in a wind tunnel?

To minimize the boundary layer flow into the test section Signup and view all the answers

What is the consequence of flow separation in the contraction region?

Degraded flow uniformity and steadiness Signup and view all the answers

What is the effect of a finite-length inlet contraction on the wall static pressure distribution?

A maximum pressure value at the entrance and a minimum at the exit Signup and view all the answers

What is the primary factor that dictates the final turbulence intensity levels in the test section?

The length of the contraction Signup and view all the answers

What is the desired flow characteristic at the exit of the contraction?

Uniform and steady Signup and view all the answers

Study Notes

Airframe contamination by ice, frost, snow, mud, or slush increases parasite drag coefficient, and severe airframe icing affects the airframe's area.
De-icing and anti-icing devices are employed on prone areas to reduce parasite drag.
Induced drag is caused by wing tip vortices, which occur when an airfoil is flown at a positive angle of attack, resulting in a pressure differential between the upper and lower surfaces.
The pressure difference causes air to move from the bottom of the airfoil outward from the fuselage around the tips, creating a whirlpool of air called a vortex.
The wing must be flown at a higher angle of attack to replace the lost lift, increasing drag, and lower indicated air speeds result in stronger vortices and greater induced drag.
Flaps are devices used to increase lift during takeoff and landing, and different types include plain, split, slotted, Fowler, slotted Fowler, Gouge, Junkers, Zap, and Krueger flaps.
Types of drag include skin friction drag, form drag, profile drag, interference drag, parasite drag, induced drag, and wave drag.
Parasite drag varies with the square of the indicated air speed and is affected by the frontal area presented to the airflow.
Factors affecting induced drag include the size of lift, aircraft speed, aspect ratio, and weight, and induced drag decreases with increasing speed and aspect ratio.
Wing end plates and tip tanks can reduce induced drag, as they restrict tip vortices and reduce the wing bending moment.
Turbulence in wind tunnel tests can produce incorrect measurements of drag, lift, and velocity profiles, and can alter the behavior of the boundary layer and skin friction.
Hot-Wire Anemometry is a chief research tool for measuring turbulent air/gas flow parameters such as turbulent intensity, mean velocity, and root mean squares.
The contraction of the wind tunnel should be kept long to minimize boundary layer growth and reduce the effect of Gortler vortices, ensuring uniform and steady flow into the test section.

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Description

Learn about the different types of flaps used in aircraft, including plain, split, slotted, and Fowler flaps. Understand the history and purpose of flaps, and how they affect drag measurements.