Drag Flashcards
Assuming airspeed remains constant, a higher angle of attack will produce less form drag than a lower angle of attack.
Select one:
True
False
Larger angles of attack will expose more frontal area to the oncoming airflow and move the separation point of the airflow forwards, both resulting in a greater pressure difference, more wake turbulence and greater form drag overall.
The correct answer is ‘False’.
Select all the properties of turbulent flow within the boundary Layer:
Select one or more:
a. Normally the first type of flow within the boundry layer
b. Normally the second type of flow in the boundary layer
c. 2mm thick
d. Particles intermix
e. Uniform increase in velocity
f. Eddies and swirls
g. 2cm thick
h. Particles slide smothely over each other
Particles intermix
Eddies and swirls
2cm thick
Normally the second type of flow in the boundary layer
Fineness Ratio is defined as the ratio between…..
Select one:
a. Chord and Span
b. Chord and Thickness
c. Span and Depth
d. Depth and Thickness
The effectiveness of a streamlined shape is determined by its FINENESS RATIO, the ratio between the length of a body, to its depth, (or thickness).
The correct answer is: Chord and Thickness
elect the correct statement from the options below:
Select one:
a. Skin Friction Drag ∝ IAS
b. Skin Friction Drag ∝ Surface Area²
c. Skin Friction Drag ∝ Surface Area
d. Skin Friction Drag ∝ Surface Area²
Bigger surfaces exposed to the airflow mean more particles are exposed to sheer stress and more skin friction is generated. Double the surface area and you’ll double the skin friction drag. The problem is we need the wings to have surface area in order to produce lift, which restricts the amount we can reduce it.
The correct answer is: Skin Friction Drag ∝ Surface Area
Select from the options below, the conditions that would be needed to produce maximum Induced drag.
Weight
Angle of Attack
Coefficient of Lift
Airspeed
The correct answer is: Weight → High, Angle of Attack → High, Coefficient of Lift → High, Airspeed → Low
Select the correct statement from the options below:
Select one:
a. Interference Drag ∝ IAS²
b. Interference Drag ∝ 1 / IAS²
c. Interference Drag ∝ IAS
d. Interference Drag ∝ IAS³
The other factor that affects interference drag is the same as form and skin friction, airspeed. Interference drag is proportional to the square of the speed.
The correct answer is: Interference Drag ∝ IAS²
Answer the question provided using the options below:
The least coefficent of drag occurs at which angle of attack?
Select one:
a. Around zero degrees
b. At the VMD angle
c. At the stalling angle of 16 degrees
d. At minus 4 degrees
The minimum coefficient of drag occurs around zero degrees. As the angle of attack increases, the coefficient of drag increases, gradually at first, and then more rapidly at higher angles until the stalling angle, where it dramatically increases as the airflow separates from the aerofoils.
The correct answer is: Around zero degrees
Complete the sentence below by filling in the missing word:
Vorticies at the wing tips lead to the production
of ————-behind the wing
Wing tip vortices produce downwash behind the wing
Parasite Drag is greatest at high airspeeds
Select one:
True
False
True
Select the correct statement from the options below:
Select one:
a. Skin Friction Drag ∝ IAS
b. Skin Friction Drag ∝ 1 / IAS
c. Skin Friction Drag ∝ IAS³
d. Skin Friction Drag ∝ IAS²
The correct answer is: Skin Friction Drag ∝ IAS²
Total Drag is least at low airspeeds
Select one:
True
False
Total Drag is least at VMD when the combination of parasite drag and induced drag are least. In the Diamond DA-40 this is at 75 kts.
The correct answer is ‘False’.
Pressure differences along the wing cause —— flow.
spanwise
Total Drag is least at high airspeeds
Select one:
True
False
Total Drag is least at VMD when the combination of parasite drag and induced drag are least. In the Diamond DA-40 this is at 75 kts.
The correct answer is ‘False’.
What is the angle of attack that ensures efficient flight at the highest Lift / Drag Ratio?
The best lift to drag ratio occurs at around 4.0 degrees angle of attack where the aircraft is producing the most lift and the least drag possible.
The correct answer is: 4
Form Drag = Drag due to ______ between forward and rear surfaces. Observed by the separation of airflow, causing wake turbulence
pressure difference
The shear stress between levels of air in boundary layer
→ Skin Friction Drag,
The forces required to separate air particles through the different levels, and move them at different speeds
→ Sheer Stress
Thin zone next to the surface where the effects of viscosity are observed
→ Boundary Layer,
Tendency for molecules of a fluid (gas or liquid) to “stick together” and cling to any solid surface they come into contact with.
→ Viscosity,
Location where flow changes from Laminar to Turbulent
→ Transition point,
