Principles of Flight: Airplane Study Notes

• These study notes cover the principles of flight for airplanes, in compliance with (EU) No. 1178/2011 and AMC FCL.115, .120, .210, .215.

Forces Acting on a Gliding Airplane

• Stationary gliding occurs when the sum of air forces compensates for the gravity force.

Extending Flaps

• Extending flaps increases aerofoil camber, which decreases the minimum speed.

Preventing a Spin

• A spin after a single-wing stall and pitch-down moment can be prevented by applying rudder opposite the lower wing and releasing the elevator to build up speed.

Longitudinal Stability

• With normal gliding, a C.G. position beyond the rear C.G. limit is most dangerous.

Static Pressure of Gases

• The static pressure of gases works in all directions

International Standard Atmosphere (ISA) Parameters

• ISA parameters include 1013.25 hPa at MSL and 0° C at MSL, with an environmental lapse rate of 2°/1000 ft.

Bernoulli's Equation

• Bernoulli's equation states that total pressure equals dynamic pressure plus static pressure for frictionless, incompressible gases.

Airflow Around a Body

• If surrounded by airflow (v>0), an arbitrarily shaped body produces drag.

Aerodynamic Forces

• All aerodynamic forces can be considered to act on a single point called the center of pressure.

Center of Pressure Origin

• The center of pressure indicates the theoretical point of origin for all aerodynamic forces of the profile.

Aerofoil Drawing Points

• Number 1 in the drawing corresponds to the chord line.
• Number 2 in the drawing corresponds to the angle of attack.
• Number 3 in the drawing corresponds to the camber line.
• Number 4 in the drawing corresponds to the camber.

Angle of Attack

• The angle between the chord line and the direction of the oncoming airflow defines the angle of attack.
• The angle of attack is the angle is between the chord line and the oncoming airflow.

Laminar vs Turbulent Boundary Layer

• The figure shows a Laminar boundary layer.
• The turbulent boundary layer is shown in the second figure.

Aspect Ratio

• The ratio of span and mean chord length defines aspect ratio.

Aerofoil Points

• Number 2 on the aerofoil represents the transition point.
• Number 3 indicates the separation point.

Vortex Development

• Vortex development starts during the take-off run when setting take-off power.

Streamlined Shape

• A streamlined shape has the lowest drag compared to other shapes, with other parameters constant.

Stagnation Point

• At the stagnation point, streamlines divide into airflow above and below the profile.

Pressure Pattern for Lift

• The pressure pattern at a lift-generating wing profile passed by airflow includes low pressure above, and higher pressure below the profile.

Center of Pressure Position

• The center of pressure at a positively shaped profile moves to the trailing edge as the angle of attack becomes smaller.
• The center of pressure at a positively shaped profile moves to the leading edge as the angle of attack becomes greater.

Center of Pressure with Increasing Angle of Attack

• With increasing angle of attack, the position of the center of pressure moves forward until reaching the critical angle of attack.

Lift Proportionality Before a Stall

• During regular flight, angle of attack is approximately directly proportional to the lift of the wing shortly before a stall.

Angle of Attack and Lift

• Increasing the angle of attack too far may result in a loss of lift and an airflow separation.

Airflow with Increasing Angle of Attack

• If the angle of attack increases, the stagnation point moves down.

Airflow with Decreasing Angle of Attack

• If the angle of attack decreases, the stagnation point remains constant

Angle Alpha

• Angle alpha (α) is angle of attack

Change of Profile Shape

• With a constant angle of incidence, the change of the profile shape is geometric washout

Stall Characteristics Improvement

• To improve stall characteristics, the wing is twisted outwards and the angle of incidence varies spanwise, known as geometric washout.

Aerodynamic Washout Benefit

• A benefit of aerodynamic washout is that at high angles of attack, the effectiveness of the aileron is retained as long as possible.

Angle of Attack Statement

• A too large angle of attack may result in a loss of lift.

Doubling Airflow Speed

• If you double the airflow speed, the parasite drag coefficient does not change.

Drag Coefficient

• The drag coefficient cannot be lower than a non-negative, minimal value.

Pressure Compensation

• Pressure compensation on an aerofoil occurs at the leading edge.

Large Induced Drag Production

• A small aspect ratio is likely to produce large induced drag..

Induced Drag

• Induced drag is generated at the trailing edge of the wing.

Interference Drag

• Interference drag is generated at the wing root.

Total Drag Curve

• Curve 3 represents the total drag.

Induced Drag Curve

• Curve 1 represents the induced drag.

Parasite Drag Curve

• Curve 2 represents the parasite drag.

Pressure Drag

• Pressure drag, interference drag and friction drag belong to the group of parasite drag.

Non-Parasite Drag

• Induced drag is NOT skin-friction drag

Parasite Drag

• Parasite drag increases with increasing airspeed.

Airspeed and Drag Change

• Induced drag decreases and parasite drag increases with increasing airspeed during a horizontal and stable cruise flight.

Wing Shape

• Elliptical shape has the lowest induced drag

Drag in Lift Generation

• Induced drag is directly connected to lift-generation on an aerofoil.

Decreasing Airspeed

• Decreasing airspeed increases the induced drag during a horizontal and stable cruise flight.

Induced Drag During Cruise Flight

• During horizontal cruise flight, induced drag decreases with increasing airspeed

Total Drag Direction

• The total drag acts in the direction of the airflow.

Total Drag Composition

• Total drag included parasite drag, and induced drag

Minimum Total Drag

• The total drag at its minimum when Parasite drag is equal to induced drag

Total Drag Statement

• Total drag has a minimum at a certain speed and increases at higher as well as lower speeds.

Total Drag

• Induced drag, form drag, and skin-friction drag contribute to total drag

Ground Effect

• The landing distance decreases in any case with ground effect

Stall Condition

• Lift decreases and drag increases when approaching a stall condition.

Stall Action

• In the event of a stall, it is important to decrease the angle of attack and increase the speed

Stall

• With an increasing angle of attack, the stall will begin at the Bottom side near the leading edge.

Lift During Stall

• Durring a stall the lift decreases and there is an increase in the drag

Critical Angle of Attack

• The critical angle of attack is independent of the weight.

Decreased Stall Speed

• Decreasing weight leads to a decreased stall speed Vs (IAS).

Stall Speed

• Stall speed increases with increasing weight.

Stall Warning

• The stall warning activates just before reaching VS.

Stall Warning Activation

• In motorplanes, the stall warning is usually activated by a change of the stagnation point.

Pilot Reaction to Stall Warning

• The pilot should raise the nose to decrease airspeed when an engaged stall warning sounds.

Ailerons During Spin Recovery

• During recovery the ailerons should be kept neutral.

Flaps for Landing

• Extending the flaps for landing at a constant angle of attack increases the lift coefficient before reaching the maximum lift coefficient.

Flap Extension

• Flap extension causes an decreased glide angle and a decreased minimum speed

Lift-Increasing Effect of Flaps

• Increasing the aerofoil camber provides a lift-increasing effect when using flaps.

Factor Changed by Flaps

• Deploying flaps for landing can change the trim condition.

Fowler Flap

• A Fowler flap works as a Profile-like flap is extended from the trailing edge of the wing.

Landing Aids

• Flaps may not be retracted suddenly near the ground

Lift Based on Landing Flap

• The increase in lift from a landing flap is based on an increase of the effective angle of attack

Flap Use at Take-off

• The drag would be too high if the flaps are used at take-off.

Flaps During Acceleration

A shorter take-off run is caused when takeoff with flaps in the take-off position.

Aircraft Operating Handbook

• After increasing the engine power in a go-around, the flaps may be retracted to a middle position provided that no other procedure is described in the Aircraft Operating Handbook.

Relationship with Flaps to lower position

• Lift increases, and drag increases when setting flaps to a lower position

What has to be considered

• flaps may only be retracted stepwise at a safe height close to the ground.

Boundary Layer

The boundary layer turns from laminar to turbulent at the transition point.

Laminar layer

• The stagnation point and the transition point marks the Laminar layer on the aerofoil.

Boundary Layers

• Laminar boundary layer along the complete upper surface with non-separated airflow is a type of boundary layer found on an aerofoil.
• The turbulent boundary layer is thicker and provides less skin-friction drag.

Aeroplane Icing

• Ice arise most on the upper und lower side of the wing's trailing edge while in flight.
• "Lateral stability" is referred to as stability around the longitudinal axis.

Lateral Stability

• Vertical tail provides lateral stability to an airplane.

Static Stability

• An aircraft distorted by external impact will return to the original position to exhibit static stability

Statically Unstable Aeroplane

• A statically unstable aeroplane becomes more stable at higher speeds

Straight and Level Flight

• Centrifugal force does NOT act during straight and level flight

Constructive Feature

Wing dihedral is a constructive feature is shown in the figure?

Longitudinal Stability

• Downforce at the elevator provides longitudinal stability to an airplane in normal configuration (empennage at tail). "Longitudinal stability" is referred to as stability around the lateral axis

Center of Gravity, the Center of Influence.

• Stability around which axis is strongly influenced by the center of gravity's position on the Lateral Axis. -"Directional stability" is referred to as stability around the vertical axis.

Directional Stability

• Large vertical tail is what structural provides directional stability to an airplane.

Rotations on Aircraft Axes

• Vertical axis, front axis, longitudinal axis dictates how an aircraft can move around which axis
• Rotation around the vertical axis is called "Yawing."
• Aircraft rotation is called "Pitching," during rotation around the lateral axis.
• "Rolling is the rotation" is for Rotation.

The Angle of Attack

is smaller than in a climb in straight and level flight with constant engine performance

Elevator, it's function

• stabilizes how an aeroplane functions around the lateral axis

Elevator Deflection, Maneuvers

• deflection is increased on an elevator with a rear centre of gravity for a specific maneuver's

Elevator Deflect

• during take-off rotation is increased for a front centre of gravity by elevator deflection..

Aircraft Elevator moves

• Deflecting the elevator upwards results in shifting the center of gravity backwards..

Center of Gravity Positon

• assure a correct and safe center of gravity position on WHAT during only correct loading

Rotation, vertical axis

• rotation is a vertical axis, Yaw,

Rudder Deflections

• result in a turn of the aeroplane around the vertical axis

Rudder Deflections

• resulting in a turn that deflect to the left causing yawing

Ailerons During Turn to the Left

• What is being deflected ailerons during A Turn of which the left resulting in an Left Aileron Is

Differential Ailerons

• During the motion it is when right aileron moves down more than the left aileron moves up during deflection adverse yaw is the advantage of differential aileron movement
• "compensate for adverse differential- defletion

Aileron

• to ensure an Differential is there Aileron

Aircraft

right roll

Rudder Balance

• The aerodynamic rudder balance is designed to reduces the control stick forces.

Features

aerodynamic provides less

Rudder Balance

• the static rudder balance control

flutter be prevented

a rudder ensures

Cruise Flight & constant setting.

during the action that is ensured .

Trim tab & control What

ensure

###Trim and indicator. at the elevator the following will be

Wing and Loading

a wing is a description for area

• The load factor increases during cruise flight because of an upward gust.
• The load factor decreases during cruise flight because of a downward gust.

Constant speed,

• high is pitch with a higher speed propeller

propoller",

range of operation to greater efficient for higher operation range propoller

Nearly constent.

Nearly an constent load by a over is for

After an engine failure, the windmilling propeller generates drag rather than thrust.

Descent at idle power

During a descent at idle power with constant speed, the propeller lever is moved backwards which will cause Propeller pitch to increase, and sink rate to decrease

flight state.

what drag

Study notes on the principles of flight for airplanes, compliant with (EU) No. 1178/2011 and AMC FCL.115. Covers forces acting on a gliding airplane, extending flaps, preventing spins, and more. Also contains information about International Standard Atmosphere (ISA) parameters.