Chapter 2 - Air / Airspeed Flashcards
The mass of a gas is?
It’s density = 1.225 kg/m^3
How do we get mass flow round an a/c?
Speed x Cross sectional area x density
Air density decreases if
Px decreases
Temp increases
Humidity increases
AD can proportional to
AD proportional to P/T
Static pressure is measured in
N/m^2, Is known as row (P)
As you increase altitude Static pressure will?
Decrease
Cold day = for density
More dense
0 kelvin =
Absolute 0 = no molecule movement
If the Viscosity is high =
Thick - syrup like
Why is humid air less dense
Because Air molecular weight is much more and when the WV starts occupying the space as well it makes the air less dense.
What does high humidity do to density
Decreases it
Which height is the air pressure half and 25%
18,000
34,000
Which height is the density half and 25%
20,000 feet
40,000 feet
In terms of physics how can a/c stay airborne
If the work on the air is enough to oppose the force of gravity
If we want to know how much force an aircraft can generate - what do we need to know
speed and air density
TAS =
True Airspeed - the speed at which the aircraft is passing through the air
Dynamic pressure =
1/2 density of the air x TAS^2
The force generated by dynamic pressure can become?
very large
If we increase density - dynamic pressure will
increase
If we increase TAS - dynamic pressure will
increase rapidly - x4
What is dynamic proportional to
IAS
How does a IAS work
Basic Total Px minus Static = Dynamic
Dynamic Px enters a pitot tube and is tubed to the IAS where it goes into a capsule.
Surrounding the capsule is static Px
What is instrument error?
Errors caused by the limitation of the manufacturing process
What are Pressure errors
Because of the position or orientation of the pitot or static port doesn’t receive all of the airflow
What are compression errors
When travelling at high speed the air can compress in the pitot tube therefore artificially raising the density
What is CAS
Calibrated Airspeed - which is correct for instrument and pressure errors via an Air data computer
What is EAS
Equivalent Airspeed - which is corrected for compression errors
At low speeds what is the difference between CAS,EAS and IAS
Small but bigger at high speeds
ICE Tea is Pretty Cool Drink
Gives the order for airspeeds
