Chapter1 Air,Atmosphere,Airspeed Flashcards
What is a fluid
A fluid is a liquid or gas that has an ability to flow
What is Air
Air is the name for the particular mix of gases in our atmosphere.
Air is a fluid and has all the properties of a fluid.
What is Density
The mass of gas per unit volume.
Density of air at MSL
1.225kg per m*3
Define Mass Flow
Mass flow is the amount of mass of air which flows through a given volume of space.
What are the Aerodynamic forces and how are they produced
Forces produced by doing work on the air. Lift,Thrust,Drag,Weight.
Only produced by an aircraft in motion.
What affects Air density
Air density will decrease if the air pressure reduces, temperature increase, humidity increases.
What is Mass flow dependent on
Depends on density of air. Greater air density faster the flow.
Provided by location/altitude.
Depends also on Speed which is provided by aircraft. Greater the speed greater the mass flow.
Provided by plane.
What is static pressure
The Pressure exerted by a fluid(air) on a body when it is at rest. When air comes into a stationary object its puts pressure on it. Pressure is felt equally in all directions.
What happens to static pressure with altitude
Decreases as you increase in altitude. less air molecules so less air weighing down.
What is Viscosity
Viscosity is the stickiness of a fluid. A fluids resistance to flow. Air is Viscous.
What is Humidity
Concentration of water vapour in the air. Increasing Humidity reduces air density as vapour particles mix with air particles.
What is Dynamic Air pressure
The pressure exerted onto a body due to it being in motion. Used to measure speed of aircraft in air.
Equation for Kinetic Energy
0.5x p(rho) x v*2
P(rho) is the density of the air
V is velocity of air flow
Effect of air density on dynamic pressure
If the density of air halves dynamic pressure will halve. If density doubles dynamic pressure doubles.
Total Air pressure
Dynamic pressure+ Static pressure
Effect of TAS on dynamic pressure
Doubling the TAS produces 4 times the dynamic pressure.
Due to the v*2
Four Types of Airspeed
IAS-indicated air speed
CAS-calibrated air speed
EAS-Equivalent air speed
TAS-True air speed
What is IAS
Indicated air speed. Shown by an air speed indicator. Calculated by the amount of dynamic pressure exerted into a pitot tube.Increase in IAS results in Increased dynamic pressure.
What is CAS
CAS is IAS corrected for instrument error(limitations of the manufacturing process) and positional error(no perfect place to put pitot tube to align perfectly with airflow.)
What is EAS
EAS is CAS corrected for compressibility. At high speeds air entering pitot tube becomes compressed which raises its density giving incorrect measurements of pressure
What is TAS
True Air Speed.
Actual speed of aircraft relative to the air. Also TAS is EAS corrected for density.
What is the relationship between density pressure and temperature
Air density is proportional to pressure but inversely proportional to temperature.
