Deck 1 Flashcards by Unknown Unknown

What are the 3 zones of the atmosphere we consider when speaking about aircraft

Troposphere
Tropopause
Stratosphere

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What is the height of the Troposphere

11km

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At what rates do temperatures drop when ascending through the atmosphere

2 degrees Celsius per 1000ft
6.5 degrees Celsius per 1000m

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What are the ISA values for temperature, pressure and density

15 degrees Celsius
1013.2 millibar
1.226kg/m cubed

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What is the definition of viscosity

A fluids resistance to internal friction

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How are the AoA and AoI measured

AoA - angle between the chord line and relative air flow

AoI - angle between chord line and datum line

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What is the aspect ratio and how is it calculated

The ratio of span to chord
Span / chord
Span^2 / area

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What is wash out and wash in

Wash out - Decrease in AoI towards the wing tip

Wash in - Increase in AoI towards the wing tip

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What is upwash and down wash

Upwash - Upwards flow of air before reaching the aerofoil

Downwash - Downwards flow of air after passing aerofoil

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What are the 4 main aerofoil planforms

Rectangular - simplest to manufacture and use

Tapered - Chord length changes from wing root to wing tip

Swept - can be both forward and back swept

Delta - fighter jet

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What are the 2 equations relating to subsonic flow

Bernoullis equation
Conservation of mass flow equation

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What does the conservation of mass flow equation state

The mass of air at any point entering, passing through or leaving a pipe must be constant

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What does bernoullis equation state

P1 + 1/2 pv1^2 =1 P2 + 1/2pv2^2

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What happens to air when is passes through a Venturi

Velocity will increase, pressure will drop

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What is the total reaction

The resultant force of the drag and lift

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What happens to the CoP and AoA increases

Will initially move 20% forward along the chord line, then move 30% backwards

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What is free stream flow

Air unaffected by the passage of aircraft through it

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What is a streamline

The path traced by a particle in a steady fluid flow

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What is the boundary layer

A thin section of slow moving air surrounding an aircraft, typically 0.1-0.2mm in thickness

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What is the separation point

Where turbulent flow separates from the aerofoil shape

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What happens to the fineness ratio when and aerofoil is streamlined

The fineness ratio will increase

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What is stall defined as?

When an increase in AoA no longer produces an increase in lift

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What is the standard stall angle

15-16 degrees

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What is the stalling speed

The slowest an aircraft can fly to produce sufficient lift to overcome its weight

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What is spanwise drift

The movement of air laterally from wing root to tip or vice versa

What 6 factors affect the total reaction

Density Air velocity Wing area AoA Surface finish Aerofoil shape

What are the equations for the Coefficient of lift and drag

1/2pv^2 x S x C (L/D)

What is the most effective AoA in straight and level flight

4 degrees

What are the 3 aerofoil classes

High lift High speed General purpose

What are the 4 leading edge lift augmentation devices

Slots Slats Krueger flaps Droop nose

What are the 3 trailing edge lift augmentation devices

Single, double or triple slotted fowler flaps Plain flaps Split flaps

What 2 sections make up total drag

Lift dependant Non lift dependant (parasite)

What 3 sections make up lift dependant drag

Form Drag Skin friction Induced drag

What 3 sections make up non lift dependant drag

Form drag Skin friction Interference drag

What 3 methods are used to control the boundary layer

Vortex Generators Blowing Suction

What are the effects of ice forming on aircraft

Aerodynamics will be affected Weight increase Vibration on moving parts Controls stiff Pressure instruments incorrect Comms degraded Vision impaired Undercarriage locked Engine intakes blocked or restricted

What parts are most vulnerable to ice formation

Areas with a thin cross section

Where and how does packed snow form

Leading edges, nose and air intakes Forms on non streamlined sections below 0 degrees when flying in or underneath snow clouds

What is hoar frost and how does it form

Light icing Forms on clear nights, rapid descent from cold air into moist air Take off on a frosty morning climbing into moist air

What is the basic stalling speed

The speed below which a clean aircraft with the engines throttled back cannot maintain straight and level flight

What conditions must be met to perform a maximum radius turn and minimum radius turn

Wing load must be as low as possible Air must be as dense as possible

What does the manoeuvre envelope show

Comparisons of capabilities of aircraft Performance of products Design requirements for new aircraft

What are the axis labelled on the manoeuvre envelope

Vertical axis - load factor Horizontal axis - EAS

What are the G limits for training, fighter and transport aircraft

Trainer and fighter - +7 -> -3.5 Transport - +2 -> -0.5

What is the safety factor on velocity

5-10%

What is the safety factor on load factor

50%

What information can you gather from the manoeuvre envelope

Basic stalling speed Load factor at any height and speed Max EAS at any height Stalling speed at any height and load factor

What is positive stability (stable)

When an object will return to its original position

What is negative stability (unstable)

When an object will never return to its original position

What is neutrally stable

What an object will not return to, nor carry on away from its original position

Around which axis is the rolling motion

Longitudinal axis

Around which axis is the pitching movement

Lateral axis

Around which axis is the yawing motion

Normal axis

What methods can be used to increase lateral stability

Dihedral (upwards angled wings) High fin High wing Sweep back

What 3 devices give control of rolling pitching and yawing

Rolling - Ailerons Pitching - Elevators Yawing - Rudder

What ways are there to overcome adverse aileron yaw

Coupled controls to the rudder Differential ailerons Frise ailerons

What methods are there to overcome high speed ailerons reversal

Wing strengthening Inner and outer wing aileron sets Spoilers on down going wing

What 4 methods are used to assist the pilot in moving the flight controls

Horn balance Inset hinge Balance tab Spring tab

What is flutter

The rapid violent oscillation of the aerofoil

How can flutter be countered

Using weights to bring the CoG forward of the hinge line

Air is deemed incompressible at what air speed

150m/s

What is the total pressure

The dynamic and static pressure added together

Where is spanwise drift the weakest

At the root of the wing

The size of the vortex will depend on what

The size of the wing tips

How do you increase directional stability

Make fuselage longer Make the fin taller Ventral fin Dorsal fin

How would you increase longitudinal stability

Make Horizontal stabilisers larger or love them rearward

How would you increase lateral stability

High fin High wing Dihedral Sweep back