Exercise 3: International Standard Atmosphere Model
Objective : What I want you to learn?
To Create a Python Code for Calculating the Properties of Atmosphere at any given altitude under the International Standard Atmosphere
Rationale : Why this is useful to you?
The properties of the Atmosphere at the given altitude are required for calculating the Flight Performance of the Aircraft.
Learning Outcomes : What I want you to do after completing this topic?
Calculate the Properties for atmosphere at a given altitude under ISA Conditions using the Python Code
Generate the Plots of Variation of Temperature, Pressure and Density Variation along the Altitude.
Introduction to International Standard Atmosphere
International Standard Atmosphere (ISA) is a hypothetical model – representative of an ideal atmosphere based on the thermodynamic equation, as defined by the International Civil Aviation Organization, devoid of water vapor, wind, and turbulence. It uses a standard reference for pressure, density, viscosity, and temperature at different altitudes throughout the atmosphere. It consists of a table of values and indicates how these values change over a range of altitudes. ISA does not change by season or region of flight. It is only impacted when altitude decreases or increases.
The Earth’s atmosphere is constantly changing, therefore, hypothetical models were developed as an approximation of what may be expected assuming the air does not contain dust or moisture and there are no winds or turbulence. These models are known as “standard atmospheres”. Their use is necessary for aircraft development, for studying their performance, for comparing the performance of different aircraft and for many other aeronautic and aviation science applications.
A concept of the standard atmosphere was developed to standardize calibration of pressure in altimeters, for studying the performance of aircraft engines where knowledge of air density, pressure and temperature at mean sea level (MSL) and their distribution as a function of altitude is essential. The International Standard Atmosphere is one such model. The International Standard Atmosphere “is intended for use in calculations and design of flying vehicles, to present the test results of flying vehicles and their components under identical conditions, and to allow unification in the field of development and calibration of instruments.”
Variation of Temperature, Pressure and Density
Python Code:
Assignment 3:
Question No 1:
Define a Function in Python/MATLAB to calculate the Pressure and Density at a Given Altitude under International Standard Atmosphere and Plot the variation with the Altitude.