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What are the primary flight controls of an airplane?
Ailerons, Elevators, Rudder
Which control surface is primarily responsible for controlling the roll of an airplane?
The primary function of elevators is to control the yaw of an airplane.
False
__________ are high-lift devices that are located on the trailing edge of the wings and are used to increase lift during takeoff and landing.
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What are the knowledge level indicators defined as for Category A, B1, B2, and C aircraft maintenance licence?
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What does Level 1 knowledge indicate for applicants?
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Level 2 knowledge entails understanding theoretical fundamentals and practical aspects of the subject.
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Level 3 knowledge requires a detailed understanding of the theoretical and practical aspects of the subject, and a capacity to combine and apply ______ elements of knowledge.
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What does CG stand for in aircraft terminology?
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What factors determine the position of the CG in an aircraft?
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The position of the pressure point in an aircraft is fixed.
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Variable incidence stabilisers are used in high-speed Transport category ________________.
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What is the primary purpose of ailerons?
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Which flight control surface is responsible for pitch control?
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What type of aircraft control surface is used for yaw control?
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Which control surface on an aircraft is used for longitudinal control?
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What is the function of roll spoilers?
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What is the purpose of trailing edge flaps on modern aircraft?
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Which type of flap is described as a simple device consisting merely of sections of the wing's trailing edge inboard of the ailerons?
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Flaperons are ailerons that can act as flaps.
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______ are designed to improve airflow conditions at high angles of attack and slow speeds.
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What is the purpose of a trim tab on an aircraft?
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How does a balance tab work on a control surface?
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Anti-balance tabs are used when control forces are excessively heavy.
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Spring tabs help pilots of high-speed aircraft by collapsing the spring at high speeds, which deflects the tab to produce an __________ force.
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Match the following types of control surface balancing with their descriptions:
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What is the purpose of spoilers on an aircraft?
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What effect does deploying wing spoilers have on an aircraft?
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Boundary layer control devices are designed to increase wing stalls.
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______ can be installed on the leading edge of the wing to hasten a stall in a specific section of the wing.
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Match the following devices with their function:
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What is the term used to describe the speed at which some air over the wings may be accelerated to Mach 1.0?
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What is the effect of sweeping the wing back on the critical Mach number?
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What are the three types of pressure waves mentioned regarding shock waves?
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When the airstream passes through a normal shock wave, its direction does not change, but it slows to __________ speed.
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What is the term used for the range where a mixture of subsonic and supersonic flows exist?
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In low-speed flight, air is considered incompressible.
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What does the Mach number represent?
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Flight below Mach 0.75 is called _______ flight.
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Match the flight speed range with its characteristics:
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Study Notes
Category B1 Licence - Aeroplane Aerodynamics and Flight Controls
- The Category B1 Licence is divided into three knowledge levels: Level 1, Level 2, and Level 3, indicating the level of knowledge required for each subject.
Knowledge Levels
- Level 1: Basic knowledge, requiring a simple description of the subject using common words and examples.
- Level 2: General knowledge, requiring an understanding of theoretical fundamentals and the ability to apply that knowledge.
- Level 3: Detailed knowledge, requiring a capacity to combine and apply separate elements of knowledge in a logical and comprehensive manner.
Aeroplane Axes and Primary Flight Controls
- An aeroplane has three axes of rotation: longitudinal, lateral, and vertical.
- Primary flight controls include ailerons, elevators, and rudder.
Roll Control
- Roll control is achieved through the use of ailerons and spoilers.
- Ailerons are movable surfaces on the wings that, when moved, increase lift on one side and decrease lift on the other, causing the aeroplane to roll.
- Roll spoilers are small, hinged surfaces on top of the wing that can be extended to increase drag and reduce lift, helping to roll the aeroplane.
Pitch Control
- Pitch control is achieved through the use of elevators and stabilizers.
- Elevators are movable surfaces on the tail that, when moved, increase or decrease lift, causing the aeroplane to pitch up or down.
- Stabilizers are fixed surfaces on the tail that provide stability and help to maintain the aeroplane's pitch.
Yaw Control and Rudder Limiters
- Yaw control is achieved through the use of the rudder.
- Rudder limiters are safety devices that prevent the rudder from moving too far, preventing loss of control.
High-Lift Devices
- High-lift devices include flaps, slats, and leading edge devices.
- Flaps are movable surfaces on the wings that, when extended, increase lift and drag.
- Slats are movable surfaces on the leading edge of the wing that, when extended, increase lift and reduce stall speed.
Drag-Inducing Devices
- Drag-inducing devices include spoilers and speed brakes.
- Spoilers are small, hinged surfaces on top of the wing that can be extended to increase drag and reduce lift.
- Speed brakes are devices that can be extended to increase drag and reduce speed.
Boundary Layer Control
- The boundary layer is a layer of slow-moving air near the surface of the wing.
- Boundary layer control devices include wing fences, saw-cut and dog-tooth leading edges, vortex generators, and stall strips.
- These devices help to maintain the boundary layer and prevent stall.
Flight Control Tabs
- Flight control tabs are small, movable surfaces on the trailing edge of the control surfaces.
- Trim tabs are used to adjust the control surface's neutral position.
- Balance tabs are used to balance the control surface.
- Anti-balance tabs are used to counteract the balancing effect of the balance tab.
- Servo tabs are used to provide additional control force.
- Spring tabs are used to provide a mechanical advantage.
- Control surface bias ground-adjustable tabs are used to adjust the control surface's bias.
Control Surface Balancing
- Control surface balancing is the process of adjusting the control surface's weight and aerodynamic balance.
- Mass balance is used to balance the control surface's weight.
- Aerodynamic balance is used to balance the control surface's aerodynamic forces.
High-Speed Flight
- High-speed flight can be divided into three regimes: subsonic, transonic, and supersonic.
- Subsonic flight occurs at speeds below the speed of sound.
- Transonic flight occurs at speeds near the speed of sound.
- Supersonic flight occurs at speeds above the speed of sound.
Flight Control Systems
- Flight control systems include mechanical, hydraulic, and electrical systems.
- Mechanical systems use cables and pulleys to transmit control inputs.
- Hydraulic systems use hydraulic fluid to transmit control inputs.
- Electrical systems use electrical signals to transmit control inputs.
Flight Control Supporting Systems
- Flight control supporting systems include artificial feel and centring systems, yaw dampers, and mach trim systems.
- Artificial feel and centring systems provide a mechanical advantage to the pilot.
- Yaw dampers are used to prevent Dutch roll.
- Mach trim systems are used to adjust the aeroplane's trim during high-speed flight.
Balancing and Rigging
- Balancing and rigging are critical processes in ensuring the aeroplane's control surfaces are properly aligned and adjusted.
- Mass balancing is used to balance the control surface's weight.
- Control system rigging is used to adjust the control surface's aerodynamic balance.
Stall Protection Systems
- Stall protection systems are used to prevent the aeroplane from stalling.
- Stall systems include stall warning devices and stick pushers.
- Stall warning devices provide a warning to the pilot when the aeroplane is approaching stall.
- Stick pushers are used to automatically push the stick forward to prevent stall.### Aeroplane Axes and Primary Flight Controls
- An aircraft in flight is free to rotate about three axes: longitudinal, lateral, and vertical axes
- The three axes pass through the centre of gravity (CG), where the entire weight of the aircraft is concentrated
- The longitudinal axis is a straight line passing through the fuselage from nose to tail, controlling roll
- The lateral axis is a straight line passing through the CG at right angles to the longitudinal and vertical axes, controlling pitch
- The vertical axis is a straight line passing through the CG at right angles to the longitudinal and lateral axes, controlling yaw
Flight Control Systems
- Flight control systems are divided into two major groups: primary or main flight control surfaces and secondary or auxiliary control surfaces
- Flight controls modify the camber or aerodynamic shape of the surface to which they are attached, creating a change in lift and drag produced by the surface
- This rotation produces the desired changes in the flight path of the aircraft
Primary Flight Controls
- Ailerons rotate the aircraft about its longitudinal axis to produce roll
- Elevators or stabilators rotate the aircraft about its lateral axis to produce pitch
- Rudder rotates the aircraft about its vertical axis to produce yaw
Roll Control
- Ailerons extend from about the midpoint of each wing outwards to the tip
- Ailerons move in opposite directions: when one aileron goes up, the other goes down
- Aileron drag is an undesirable effect caused by the displacement of ailerons, creating adverse yaw
- Differential ailerons minimize adverse yaw by having the aileron moving upwards travel a greater distance than the one moving downwards
- Frise ailerons extend the leading edge of the up aileron below the lower surface of the wing, producing additional parasite drag to counteract induced drag
- Roll spoilers are hinged surfaces located ahead of the flaps on the upper surface of the wing, used in conjunction with ailerons to assist in roll control
Pitch Control
- Elevators are horizontal movable control surfaces mounted on the tail of the aircraft
- Elevators cause the aircraft to rotate about its lateral axis
- Stabilators, or all-movable tails, are a type of horizontal tail surface that pivots up and down from a central hinge point
- Variable incidence stabilizers adjust the angle of incidence of the horizontal stabilizer to maintain a balance of forces and prevent undesired rotation along the pitch axis
- Trimmable horizontal stabilizers use screw spindles to adjust the stabilizer to create an opposite force to compensate for changes in the CG and pressure point
Yaw Control and Rudder Limiters
- Yaw control is the rotation of the aircraft about its vertical axis, controlled by the rudder
- The rudder is attached to the back of the vertical stabilizer and moves the aircraft's nose left and right
- Rudder limiters limit the maximum deflection of the rudder as a function of aircraft speed to maintain structural integrity and prevent excessive loads
- Pedal travel limiters and rudder travel limiters work together to limit rudder deflection and maintain aircraft trimming throughout the flight envelope### Rudder Pedal Travel Limiter
- A device that limits the travel of the rudder pedal to prevent over-rotation of the rudder.
Elevons and Ruddervators
- Elevons: combine the function of ailerons and elevators; used on tailless aircraft like the Concorde.
- Movement of the control column:
- Backwards and forwards: elevons act as elevators.
- Rotating the control wheel: elevons act as ailerons.
- Mixing unit: allows simultaneous movement of the elevons to perform both functions.
Ruddervators
- Combine the functions of rudders and elevators.
- Used on aircraft with tail empennages, where the traditional horizontal and vertical stabilizers do not exist.
- Two fixed surfaces: act as both horizontal and vertical stabilizers.
- Two movable surfaces: connected through a mixing-type linkage, allowing for pitch and yaw control.
High-Lift Devices
- Introduction:
- Engineering compromises: stability vs. maneuverability, high cruising speed vs. low landing speed, etc.
- Primary flight controls: rotate the aircraft around its three axes.
- Secondary flight controls: assist or modify the effect of primary controls.
- Types of high-lift devices:
- Those that modify the amount of lift a surface produces:
- Trailing edge high-lift devices.
- Leading edge high-lift devices.
- Those that change the amount of force needed to operate the primary controls.
- Those that control the aircraft's trim.
- Those that induce drag.
- Those that modify the amount of lift a surface produces:
Trailing Edge Flaps
- Change the camber of the wing, increasing lift and drag.
- Enable landing at slower speeds and shorter runway requirements.
- Configurations:
- Plain flaps.
- Split flaps.
- Slotted flaps.
- Fowler flaps.
Trailing Edge Flap Types
- Plain flaps:
- Simple devices that consist of sections of the wing's trailing edge.
- Hinged from the top to deflect downwards.
- Increase the angle of attack, wing camber, and total drag.
- Split flaps:
- A portion of the lower surface of the wing's trailing edge can be hinged down into the airstream.
- Produce more drag at low lift coefficients.
- Slotted flaps:
- Increase the lift coefficient more than simple flaps.
- Allow air to flow from the high-pressure area below the wing to the upper surface.
- Prevent the flap from stalling.
- Fowler flaps:
- Constructed to increase the effective area of the wing and lower the trailing edge.
- Initial deployment increases wing area, providing more lift without significant parasite drag.
- Later deployment increases wing angle of attack, camber, and drag.
Slotted Fowler Flaps
- Combine the benefits of Fowler flaps and slotted flaps.
- Increase lift and drag, while preventing airflow breakaway.
Flaperons
- Combine the functions of ailerons and flaps.
- Differential movement: aileron effect.
- Collective movement: flap effect.
- Used on aircraft like the Boeing 767, 777, and 787.
Leading Edge High-Lift Devices
- Increase the camber of the wing and allow it to operate at higher angles of attack.
- Devices:
- Krueger flaps.
- Drooped leading edge flaps.
- Slots.
- Slats.
Krueger Flaps
- Hinged to the wing's leading edge.
- Deployed to increase the camber of the wing and lift.
- Used in conjunction with trailing edge flaps.
Drooped Leading Edge Flaps
- Use a jack-screw arrangement to push the leading edge of the wing against a hinge on its lower surface.
- Increase the camber of the wing and lift.
Slots
- Nozzle-shaped passages through the wing.
- Improve airflow conditions at high angles of attack and slow speeds.
- Increase the stall angle.
Slats
- Boost the extent of the low-pressure area over the wing.
- Useful only at high angles of attack.
- Movable slats can be retracted to reduce drag.
Effect of Flaps and Slats on Stall Angle
- Flaps only: reduce the stall angle.
- Flaps and slats: increase the stall angle.
Effect of Flap Deployment on Pitch
- When a flap is deployed, the bulk of the lift moves to the trailing edge of the wing.
- Produces a nose-down moment on the wing.
Drag-Inducing Devices
- Devices that disturb the smooth airflow to produce drag.
- Types:
- Wing-installed devices.
- Fuselage-installed devices.
- Used in approach and rapid descent, and during landing.
Spoilers
- Control devices that destroy lift by disrupting the airflow over a part of the wing.
- Functions:
- Speed brake: rapid rate of descent.
- Ground spoiler: increase braking efficiency.
Effect of Spoilers
- Deploying wing spoilers reduces lift, produces drag, and increases stall speed.
- Inhibited when flaps are fully extended.
Speed Brakes
- Devices that reduce airspeed and allow for steep descent.
- Types:
- Wing-mounted spoilers.
- Fuselage-mounted speed brakes.
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Description
Test your knowledge of aircraft primary flight controls, control surfaces, and maintenance license requirements. Quiz covers roll control, elevator function, high-lift devices, and knowledge level indicators for different aircraft categories.
