Aerodynmics

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What is a primary concern regarding high roll due to side-slip caused by excessive effective dihedral?

It improves the aircraft's maneuverability, allowing for tighter turns.
It can lead to oscillatory instability, specifically causing Dutch roll or spiral instability. (correct)
It reduces the aircraft's sensitivity to turbulence, providing a smoother ride.
It enhances longitudinal stability, making the aircraft easier to control during pitch changes.

In the context of oscillatory instability, what distinguishes Dutch roll from snaking?

Dutch roll is corrected by the rudder, and snaking is corrected by the ailerons.
Dutch roll is characterized by predominant rolling motion, while snaking involves mainly yawing. (correct)
Dutch roll is characterized by predominant yawing motion, while snaking involves mainly rolling.
Dutch roll primarily affects high-speed aircraft, whereas snaking is more common in slower planes.

How do dihedral and keel surface (fin and rudder size) generally contribute to oscillatory instability in aircraft?

Dihedral and keel surface have minimal impact on oscillatory instability.
Increased dihedral enhances stability, while a larger fin reduces it.
Larger dihedral and fin sizes reduce the oscillatory instability.
Greater dihedral and larger fin sizes increase the tendency toward oscillatory instability. (correct)

What is the consequence if the aerodynamic force produced by the vertical fin is significantly greater than the effect of the dihedral?

The aeroplane will tend to be spirally unstable. (B) Signup and view all the answers

What distinguishes an aircraft with passive stability from one that relies on active stability control systems?

Passive stability is inherent and doesn't require artificial stabilization systems, while active stability does. (A) Signup and view all the answers

What is the primary function of the vertical stabilizer in maintaining directional stability?

To generate a yawing moment that returns the aircraft to its original flight path. (C) Signup and view all the answers

How do sweptback wings contribute to directional stability?

By increasing drag on the wing farther ahead in a yaw, correcting the aircraft's course. (A) Signup and view all the answers

An aircraft experiences a sideslip. How does dihedral contribute to restoring lateral stability?

By increasing the lift on the lower wing and decreasing lift on the higher wing, creating a rolling moment. (C) Signup and view all the answers

What is the effect of a larger dorsal fin on directional stability?

It aids in directional stability by increasing the vertical surface area and improving yaw stability. (C) Signup and view all the answers

What is the relationship between the wing's center of lift, the center of gravity (CG), and longitudinal stability?

The wing's center of lift being behind the CG creates a nose-down pitching moment, counteracted by the horizontal tail surface. (C) Signup and view all the answers

How is lateral stability primarily achieved in aircraft design?

Primarily through the design and implementation of dihedral in the wings. (D) Signup and view all the answers

Consider an aircraft in straight-and-level flight experiencing a sudden disturbance that causes it to yaw to the left. Assuming positive directional stability, what will the aircraft do?

Slowly return to its original heading due to the restoring moment created by the vertical stabilizer. (A) Signup and view all the answers

An aircraft is designed with a high degree of dihedral. What might be a potential disadvantage of this design characteristic?

Increased sensitivity to turbulence and crosswinds. (C) Signup and view all the answers

An aircraft wing is designed with a greater angle of incidence at the wing tip compared to the root. What is this characteristic called and what effect does it have?

Washin; it delays stall at the wing tip, potentially leading to abrupt stall characteristics closer to the fuselage. (C) Signup and view all the answers

An aircraft experiences roll opposite to the propeller's rotation. How can differential washout be employed to compensate for this effect?

Increase washout on the wing on the same side as the propeller's rotation. (D) Signup and view all the answers

Which of the following statements best describes the impact of in-flight icing on an aircraft's performance?

Icing causes airflow disruption, leading to decreased control and performance, and can cause the wing to stall at a lower angle of attack. (C) Signup and view all the answers

How does ice accumulation on an aircraft wing affect its stall characteristics?

Ice causes the wing to stall at a lower angle of attack and higher airspeed. (D) Signup and view all the answers

Why is maintaining balanced ice accumulation on both wings crucial during flight in icing conditions?

Unbalanced ice accumulation can lead to roll control issues and potentially hazardous flight conditions. (D) Signup and view all the answers

An aircraft wing has a wingspan of 60 feet and a wing area of 300 square feet. What is its aspect ratio?

12 (A) Signup and view all the answers

Why is the Mean Aerodynamic Chord (MAC) an important parameter in wing design?

It represents the average lift distribution across the wing. (A) Signup and view all the answers

A wing is designed so that equal amounts of wing area lie on both sides of a specific chord. What is this chord called?

Mean Aerodynamic Chord (MAC) (C) Signup and view all the answers

Which of the following best describes Dutch roll?

A combined rolling and yawing movement where the rolling predominates the motion (A) Signup and view all the answers

Increasing both the dihedral and the fin size decreases the tendency toward oscillatory instability.

False (B) Signup and view all the answers

What type of stability control system is required to fly high-speed, high-altitude aircrafts that are designed to be aerodynamically unstable?

Active Signup and view all the answers

Aircraft with passive stability have both positive static stability and positive ________ stability.

dynamic Signup and view all the answers

If the vertical fin produces a greater aerodynamic force than the dihedral, the aeroplane may be:

Spirally unstable (A) Signup and view all the answers

Which wing shape is generally considered the most efficient?

Elliptical (C) Signup and view all the answers

A higher angle of incidence at the wing tip compared to the root is known as wash out.

False (B) Signup and view all the answers

What is the primary purpose of washout in wing design?

Improve stability during stall Signup and view all the answers

The __________ is a straight line joining the leading edge and trailing edge of an aerofoil.

chord Signup and view all the answers

Match the wing characteristic with its description:

Wingspan = Distance from one wing tip to the other wing tip Aspect Ratio = Ratio of the square of the wingspan to the wing area Wing Area = The projected area of the planform bounded by the leading and trailing edges and the wing tips Mean Aerodynamic Chord (MAC) = The chord drawn through the center of the area of the aerofoil. Signup and view all the answers

Which wing design is usually the cheapest to manufacture?

Rectangular (B) Signup and view all the answers

How does ice formation on an aircraft wing affect its stall characteristics?

Decreases the stall angle of attack (D) Signup and view all the answers

The purpose of wash in is to improve the stability of the aircraft as it approaches a stall condition.

False (B) Signup and view all the answers

What is the primary function of the vertical stabilizer in relation to directional stability?

To control directional stability by creating a yawing moment that returns the aircraft to its original flight path. (D) Signup and view all the answers

An aircraft with good directional stability will require constant pilot input to maintain its course after a disturbance.

False (B) Signup and view all the answers

Directional stability is enhanced by using a large dorsal _____ and a long fuselage.

fin Signup and view all the answers

What effect does dihedral have on lateral stability during a sideslip?

It increases the angle of attack on the wing into the airflow and decreases it on the other wing, creating a stabilizing rolling moment. (B) Signup and view all the answers

Longitudinal stability refers to an aircraft's stability about its vertical axis.

False (B) Signup and view all the answers

What is the primary factor that determines the effectiveness of the stabilizer in counteracting pitch disturbances?

The distance from the CG to the tail. Signup and view all the answers

Match the following stability types with their corresponding axis of movement:

Directional Stability = Vertical Axis Lateral Stability = Longitudinal Axis Longitudinal Stability = Lateral Axis Signup and view all the answers

Oscillatory Instability

Rolling and yawing motion instability.

Dutch Roll

Oscillatory instability where rolling motion is predominant.