Module 5 Concepts Flashcards
What type of wave is sound?
Longitudinal, pressure wave
What assumptions are made for the speed of sound in air?
- Ideal gas
- Adiabatic process
What is the speed of sound a function of?
Temperature, and temperature only!
What is a Mach number?
A dimensionless quantity which is the ratio of the speed of a flow to the local speed of sound
What are the three different states that air particles can be in when flowing around an object? What is their mach number?
Subsonic if M < 1
Sonic M = 1
Supersonic M > 1
What different states can an aircraft be in with respect to mach?
Subsonic if Mfs < Mcrit
Transonic if Mcrit < M < 1.2
Supersonic if Mfs > 1.2
What is the free-stream Mach number?
the ratio of free stream airspeed of an aircraft to the free stream speed of sound
What is the local mach number?
Ratio to of particles at a location around the aircraft to the local speed of sound
What is the Critical mach number>?
The free-stream mach number when a local mach number has reached 1. Marks when the first local airflow becomes sonic.
How will increasing temperature when all other factors are constant affect affect the Mach number?
Mach will decrease
When descending at a constant CAS what will happen to Mach number under ISA?
Mach number decreases
due to:
-LSS increasing
-TAS decreasing
What happens to CAS if you climb at constant Mach through an isothermal layer?
LSS and TAS do not change
CAS will decrease due to reduction in density
What will happen to displayed Mach number if the pitot port becomes blocked during a climb?
Machmeter will over read
What happens to TAS when climbing at a constant Mach?
Decreasing (proportionally)
If both ALT and TAS are constant but Mach increases, what is happening?
Temperature is decreasing
