Aircraft Yawing Tendencies Quiz

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Questions and Answers

What is the correct definition of propeller parameters?

Propeller twist is the angle between the chord line and the rotational plane of the propeller. (correct)

Pitch refers to the distance the propeller advances in one revolution at a non-zero blade angle of attack.

Pitch is the theoretical distance a propeller would advance in one revolution at zero blade angle of attack.

Propeller diameter is the distance from the tip of one blade to the tip of the opposite blade.

Why is yaw followed by roll in an airplane?

Rolling motion generated by rudder deflection causes speed increase of the outer wing, leading to roll in the direction of turn.

Yawing motion generated by rudder deflection speeds up the outer wing, increasing lift and causing roll in the same direction. (correct)

Rudder is located above the longitudinal axis and causes a rolling moment in the same direction as yaw.

Yawing motion generated by rudder deflection speeds up the inner wing, increasing lift and causing roll in the same direction.

In a jet transport aeroplane, why does pitch up occur when thrust is suddenly increased?

Thrust line coincides with the effective pitch preventing any change in lift.

Thrust line is above the effective pitch causing a decrease in lift and inducing pitch up.

Thrust line is forward of the center of gravity causing an increase in lift and inducing pitch up.

Thrust line is below the effective pitch causing a decrease in lift and inducing pitch up. (correct)

Which of the following aileron deflection configurations is an example of differential deflection during the initiation of a left turn?

Left aileron: 5° up. Right aileron: 2° down. Signup and view all the answers

When the CG position is moved forward, what happens to the elevator deflection required to achieve a load factor greater than 1?

Larger. Signup and view all the answers

At speeds just above the critical Mach number, what happens to the Lift-to-Drag (L/D) ratio?

90% Signup and view all the answers

Rolling in an airplane refers to the rotation about which axis?

Lateral axis. Signup and view all the answers

When mass balancing is used for flutter dampening, where are the balancing weights typically located with respect to the hinge of the control surface?

Ahead of the hinge. Signup and view all the answers

Comparing a stabilizer trim system with an elevator trim system, which statement is correct?

A stabilizer trim can compensate larger changes in pitching moments. Signup and view all the answers

What generates the desired rolling moment in an aeroplane by causing a difference in lift between both wings?

Differential aileron deflection Signup and view all the answers

Why is it important to ensure that the tip of a propeller blade produces the most thrust?

To ensure that the tip produces most thrust Signup and view all the answers

How does an aeroplane react to increased drag according to the text?

Is forced downwards as a reaction to the increased drag Signup and view all the answers

Which statement accurately describes the impact of weight and altitude on gust load on an aeroplane?

When the altitude increases, the gust load increases Signup and view all the answers

How can wing flutter be prevented according to the text?

Installing anti-balanced rudder control Signup and view all the answers

Why are most transport aeroplanes equipped with protection against control jamming?

To prevent accidents in case of control malfunctions Signup and view all the answers

What is the main reason for the tendency of an airplane to yaw in the opposite direction of a turn?

Difference in induced drag on each wing Signup and view all the answers

If an airplane maintains straight and level flight at 2 times the stall speed (VS), what load factor is caused by a vertical gust at 1.3 times VS?

N = 1.65 Signup and view all the answers

Which statement about propeller blade angles is correct?

Both I and II are correct Signup and view all the answers

For any propeller, what does a large blade angle typically indicate?

Higher pitch setting Signup and view all the answers

When a jet transport airplane takes off with the center of gravity (CG) at the aft limit and the trimmable horizontal stabilizer (THS) is positioned at maximum allowable nose up position, what effect does this have?

Increases lift during take-off Signup and view all the answers

What do stick forces provided by an elevator feel system depend on?

Elevator deflection, dynamic pressure Signup and view all the answers

What happens to the propeller pitch and torque when an aeroplane's speed increases while manifold pressure remains constant?

Propeller pitch and torque remain constant Signup and view all the answers

Where do the stall speed lines in the manoeuvring load diagram originate from?

Speed = VS, load factor = 0 Signup and view all the answers

What characteristics would an aircraft have if it has less sweepback and a larger fin?

Less sweepback and a larger fin Signup and view all the answers

In a situation where an aircraft's propeller pitch decreases, what happens to the propeller torque?

Propeller torque increases Signup and view all the answers

In the figure shown, what type of horizontal control surface is depicted?

Canard Signup and view all the answers

What are the conditions when the stall speed lines in the manoeuvring load diagram originate from a point?

Flaps (and/or slats) extended or speed below a certain value Signup and view all the answers

Study Notes

Propeller Parameters and Performance

Propeller parameters define characteristics such as blade angle, pitch, and RPM, which influence efficiency and thrust production.
A large blade angle typically indicates higher thrust but can decrease RPM efficiency if too high.

Yaw and Roll in Airplanes

Yaw occurs first in an airplane due to asymmetric thrust when the aircraft turns; this precedes roll, which stabilizes the turn.

Thrust and Pitch Up

In a jet transport aircraft, an increase in thrust can result in a pitch-up because of the resultant aerodynamic force shift and the center of gravity position.

Aileron Deflection Configurations

Differential deflection is shown when ailerons move asymmetrically during a left turn, creating a lift differential that facilitates the turn.

CG Position and Elevator Deflection

Moving the center of gravity (CG) forward requires more elevator deflection to achieve a load factor greater than 1 to maintain pitch stability.

Critical Mach Number

At speeds just above the critical Mach number, the Lift-to-Drag (L/D) ratio decreases due to airflow separation and shock waves.

Rolling Axis

Rolling refers to the rotation of an airplane around its longitudinal axis.

Mass Balancing and Flutter

Mass balancing weights are typically located near the hinge of the control surfaces to dampen flutter effectively.

Stabilizer Trim vs. Elevator Trim

A stabilizer trim system adjusts the entire horizontal stabilizer, while an elevator trim system only adjusts the elevator surface.

Rolling Moment Generation

The desired rolling moment is generated by differing lift due to aileron deflection, causing one wing to produce more lift than the other.

Propeller Blade Tip Importance

Ensuring the propeller blade tip produces the most thrust is vital for maximizing efficiency and performance in flight.

Increased Drag Reaction

An airplane experiencing increased drag responds by requiring either increased thrust or a change in configuration (like a flap extension).

Gust Load Impact

Weight and altitude both impact gust loads; heavier aircraft typically experience greater loads, especially at higher altitudes where air density is lower.

Wing Flutter Prevention

Wing flutter can be prevented through design modifications, such as adding stiffness or mass balancing around control surfaces.

Control Jamming Protection

Most transport aircraft are equipped with systems to prevent control jamming, ensuring pilot control even if system failures occur.

Yawing Tendency in Turns

During a turn, an airplane tends to yaw opposite to the turn direction because of differential thrust and banking effects.

Load Factor from Gusts

If maintaining straight and level flight at 2 times stall speed (VS), a vertical gust at 1.3 times VS generates significant load factors, stressing the aircraft structure.

Propeller Blade Angles

Correct statements about propeller blade angles clarify their relationship to thrust and efficiency, impacting flight performance.

Effect of CG at Takeoff

When a jet transport takes off with the CG at the aft limit and the stabilizer at maximum upward trim, it can cause instability and difficulty in controlling the pitch.

Stick Forces and Elevator Feel System

The stick forces provided by an elevator feel system depend on speed, control surface movements, and aircraft configuration.

Speed, Manifold Pressure, and Propeller Torque

As an airplane's speed increases with constant manifold pressure, propeller pitch tends to reduce slightly while torque can increase due to aerodynamic factors.

Stall Speed Lines in Load Diagrams

Stall speed lines in the maneuvering load diagram originate from reference points where maximum load factors are critical, assessing aerodynamic capabilities.

Aircraft Characteristics with Less Sweepback

Aircraft with less sweepback and larger fins may demonstrate increased stability but reduced maneuverability during flight.

Propeller Pitch Changes

A decrease in the propeller pitch results in increased propeller torque, leading to a higher thrust output.

Horizontal Control Surface Type

The specific type of horizontal control surface depicted can indicate the design and control capabilities of the aircraft.

Conditions for Stall Speed Lines

Stall speed lines in the maneuvering load diagram originate from a specific point under conditions of high load factor expectations during flight maneuvers.

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Description

Test your knowledge on the different tendencies of an aeroplane to yaw during turns. From aileron drag to wing speeds, this quiz covers various scenarios that affect the yaw motion of an aircraft.