Induced drag a. Increases with an increase in airspeed b. Decreases with an increase in airspeed c. Increases with a decrease in airspeed d. b and c 6. Parasite drag a. Increases with an increase in airspeed b. Increases with a decrease in airspeed c. Decreases with a decrease in airspeed d. a and c 7. What is the primary factor in determining the three-dimensional characteristics of the ordinary wing. a. Span (b) b. Aspect Ratio (AR) c. Surface area (S) d. Coefficient of Lift (CL) 8. What happens to a finite airfoil (a wing) with trailing edge flaps when the flaps are lowered in flight? a. The effective camber of the airfoil will change b. The amount of lift at any given airspeed will change c. The CL of the wing will change d. a, b, and c are correct
The Correct Answer and Explanation is:
Here are the answers and explanations for each question:
5. Induced Drag
- Correct answer: c. Increases with a decrease in airspeed
Explanation:
Induced drag is a type of drag that occurs due to the generation of lift. As an aircraft generates lift, vortices form at the wingtips, and these vortices create a downwash that increases the angle of attack and contributes to induced drag. Induced drag is inversely related to the square of the airspeed. When airspeed decreases, the aircraft needs to increase its angle of attack to generate the same amount of lift, which increases the induced drag. Therefore, induced drag increases as the airspeed decreases.
6. Parasite Drag
- Correct answer: a. Increases with an increase in airspeed
Explanation:
Parasite drag is made up of form drag, skin friction drag, and interference drag, all of which increase as airspeed increases. When the aircraft’s speed increases, the air encounters more resistance because the air particles are moving faster relative to the aircraft. Form drag (due to the shape of the aircraft) and skin friction drag (due to surface roughness) both increase with higher airspeed, causing parasite drag to rise as well. Therefore, parasite drag increases with an increase in airspeed and decreases with a decrease in airspeed.
7. Primary Factor in Determining the Three-Dimensional Characteristics of an Ordinary Wing
- Correct answer: b. Aspect Ratio (AR)
Explanation:
The aspect ratio (AR) of a wing is the ratio of its span (the distance from one tip to the other) to its average chord (the width of the wing). A high aspect ratio (longer wings with a narrower chord) generally results in lower induced drag and better lift-to-drag ratios, whereas a low aspect ratio (shorter wings with a wider chord) leads to more drag and reduced aerodynamic efficiency. The aspect ratio plays a key role in determining the aerodynamic characteristics, such as lift distribution, drag, and stability, in a three-dimensional wing.
8. What Happens to a Finite Airfoil with Trailing Edge Flaps When the Flaps Are Lowered in Flight?
- Correct answer: d. a, b, and c are correct
Explanation:
When trailing-edge flaps are lowered in flight, several things happen to the airfoil’s characteristics:
- a. The effective camber of the airfoil will change: The camber refers to the curvature of the airfoil. Lowering the flaps increases the camber of the airfoil, making it more curved and improving the airfoil’s ability to generate lift.
- b. The amount of lift at any given airspeed will change: Lowering the flaps increases the lift at a given airspeed. This is because the increased camber leads to a greater coefficient of lift (CL), which directly impacts the amount of lift generated by the wing.
- c. The CL of the wing will change: The coefficient of lift (CL) increases when the flaps are lowered. This means that the wing can generate more lift at lower speeds or with the same amount of airspeed, which is essential for takeoff and landing operations.
Therefore, all of these effects are correct when trailing-edge flaps are lowered.
