Aeroplanlære - Kap 1 (Intro) Flashcards
Which two systems of units is used in aviation?
SI and Imperial
1nm = m
1852 m
1m = ft
3.28 ft
How is speed defined?
Rate of change of distance
What is speed measured in usual?
Kts
What is kts measured in?
Nm/h
What is vertical speed measured in?
Feet per minute
fpm
What is the SI unit equivalent to kts?
km/h
What is the SI unit equivalent to fpm?
m/s
What is the conversion rate of 1 m/s to kts?
m/s = 0,514 * kts
Pilot math = Halve it
What is the conversion rate of 1 kts to m/s?
kts = m/s * 3600 / 1852
How is acceleration defined?
Rate of change of velocity
How is force calculated?
F = ma
Force = Mass * Acceleration
How is acceleration calculated?
a = ΔV/Δt
Acceleration = Change in velocity / Change in time
What is mass?
The quantity of matter a body possesses
What unit is mass measured in typically?
Kg
What is the conversion rate of kg to lb?
1 kg = 2,205 lb
How is momentum defined?
An object’s mass times it’s velocity
m * V
What happens to the speed of an aircraft if the forces acting on it are equal and opposite?
The aircraft remains at rest or continue in a straight line with the same speed
What unit is force measured in?
Newtons
When will a object not accelerate?
When the forces acting on it are in equilibrium
How fast would you speed up when falling from the sky towards earth due to earths gravitational field?
9,81 m/s^2
What unit is energy measured in?
Joules
Can the total amount of energy change?
No it will always stay the same, but is converted between kinetic, potential, heat etc.
What is kinetic energy?
The energy a mass possesses due to its motion
How is kinetic energy measured?
1/2 * m * V^2
What unit is Work measured in?
Joules
How is work calculated?
Work = force * distance
How is power defined?
Rate of doing work
What unit is power measured in?
Watt
How is power calculated?
Work / time = force*distance / time = Force * speed
What is newton’s first law?
An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force
What is newton’s second law?
The acceleration of a body in a straight line is proportional to the applied force and inversely proportional to the mass of the body
What is newton’s third law?
To each and every action there is an equal and opposite reaction
What is the relative airflow relative too?
The aircraft
What point does all aircraft axes intercept?
CG
Center of gravity
What is the name of the axis which you roll?
Longitudinal axis
What is the name of the axis which you pitch?
Lateral axis
What is the name of the axis which you yaw?
Normal axis
Where is the wing tip located?
At the end of the wing furthest from the fuselage
Where is the wing root located?
Where the wing joins the fuselage
What is the wing span defined as?
The distance between the wing tips
What is the gross wing area?
The area comprising the planform of the wing and the area of the fuselage
What is the planform?
The outline shape of the wings when seen from above
What is the average chord?
The mean geometric chord length of the wing
How is aspect ratio defined?
The ratio of wing span to average wing chord
Does a glider have a high aspect ratio?
Yes
How is aspect ratio calculated?
Aspect ratio = span/chord = span^2 / area
What is sweep angle?
The degree a wing is oriented backwards or forwards
How is mean aerodynamic chord defined?
The MAC is a two-dimensional representation of the whole wing
How are dihedral wings build?
The wing tips are designed to be higher than the wing root
How are anhedral wings build?
The wing tips are designed to be lower than the wing root
How do we measure gas?
We measure it as density
Does air have a high density or low density compared to solid objects?
Low
What is air density at MSL on an average day?
1.225 kg/m^3
How is mass flow calculated?
Mass flow = Front area^2 * V * 1.225kg/m3
When will air density decrease?
- Air pressure - Decrease
- Temperature - Increase
- Humidity - Increase
Why do we fell a static pressure constantly?
Since air is considered a fluid and particles in a fluid are always moving, we feel all those collisions against us as a force
Is static pressure equal on all objects?
Yes
What is static pressure over an area measured in?
Newtons per square meter (N/m^2)
What is the symbol for static pressure?
With the greek letter “rho” = ρ
What is the temperature a result of?
The kinetic energy of the vibrating molecules
Does hot air use more space than cold air?
Yes, since particles move rapidly when they get hot
If 1° Celcius increase with 1, how many does Kelvin increase?
1°, but Kelvin is 273° less than celcius
What is viscosity?
The stickiness of a fluid
What does viscosity describe?
The degree of difficulty the molecules have when they try to flow past one another
Is water vapour heavier or lighter than air?
Lighter
What does ISA stand for?
International Standard Atmosphere
What is the ISA atmosphere?
- At MSL temperature = 15° Celcius
- At MSL pressure = 1013.25 HPa
- At MSL density = 1,225 kg/m^3
- Lapse rate is 1,98°C per 1000’ up to the tropopause
What is the temperature above the tropopause?
A constant of -56,5°C
When can an aircraft only become airborne?
When it does work on the air to produce a force to oppose gravity
Force produced as a result of during work on air is called what?
Aerodynamic force
What is TAS?
True Air Speed
The actual speed of the aircraft relative to the air
What is dynamic pressure?
The additional air pressure caused by air’s kinetic energy
How is kinetic energy calculated?
Kinetic energy = 1/2mV^2
m is the mass of an object and V is its velocity
Does air have kinetic energy?
Yes since air has mass
How is dynamic pressure calculated?
Dynamic pressure = 1/2pV^2 on each 1m^3
p is density
V is the TAS of the airflow
What is IAS short for?
Indicated Air Speed
How is IAS calculated?
Explain how the airspeed indicator measures IAS
A capsule is fed dynamic pressure and is inflated
The static pressure compresses around it
Is IAS an accurate measurement?
No it has errors
Which errors does IAS measurement have?
What is CAS short for?
Calibrated Air Speed
Which correction do CAS have compared to IAS?
Instrument errors and predictable pressure errors
Does an airliner display IAS or CAS?
CAS
What is EAS short for?
Equivalent Air Speed
Which correction do EAS have compared to CAS?
It is corrected for compressibility
How is EAS calculated?
Is it possible for IAS to exceed TAS?
Yes
Encountering a temperature inversion where warm air exists above cooler air can also cause IAS to exceed TAS because the air density measured by the pitot-static system might be greater than the actual air density through which the aircraft is flying
or
If an aircraft is flying into a strong headwind, the IAS will increase because the airspeed indicator measures the pressure differential