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Theory of Flight

By : Hardeep Singh

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Objectives

To demonstrate an understanding of  the

atmosphere and its conf iguration.

Learners should evident the use of ISA and variation

of pressure, temperature and density with altitude.

Learners to demonstrate an understanding of 

subsonic f low and its parameter.

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What is the Atmosphere?

Thin layer of gases enveloping earth heldb y the gravitational pull.

Ma jor gases: N2(78%) and O2 (21%)

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Troposphere

lowest layer; temperature decreaseswith altitude

thinnest layer (8-16 km, avg. 11 km) where weather occurs primarily heated by Earth·s surface

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Stratosphere

found above the troposphere

temperature rises with elevation

Ozone Layer located here

upper stratosphere temperature increases withaltitude due to absorption of UV (ultraviolet) radiation in the ozone layer

Note :Without the ozone layer protecting us, we could not live on the surface of the Earth!

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Mesosphere

above the stratosphere

temperature decreaseswith altitude

Meteorites and space

dust burns up in this layer

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Ionosphere

Q uartz Lake State Park, Alaska (Curtis, 1996)

defined based on electricalcharacteristics within thethermosphere

absorbs cosmic rays, gamma rays,X-rays, some UV rays

contains ions: charged electricalparticles

visible light is emitted when ionsare bombarded b y cosmic radiation

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Any Q uestions ?

Draw a diagram labelling the diff erent layers of the

atmosphere and the variation of  temperature with

increase in altitude ?

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Objectives

To demonstrate an understanding of  the

atmosphere and its conf iguration.

Learners should evident the use of ISA and variation

of pressure, temperature and density with altitude.

Learners to demonstrate an understanding of 

subsonic f low and its parameter.

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International Standard Atmosphere

(I

 S

A ) ? The ISA consists of all the important f actors like

temperature, density and pressure with respect to 

altitude.

ISA is based on the US Standard atmosphere, which

is compiled in 1962 under NASA and USAF.

Use of  ISA helps compare performance of diff erent

aircraf ts and propulsions systems.

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Sea Level Conditions

Standard Sea Level Values

Pressure : 101,325 N/m²

Density : 1.2250 Kg/m³

Temperature : 288.16 K

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Changes with increase in altitude

Temperature Density Pressure

Note : Please pay attention on the unit used for temperature , density and pressure

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Any Q uestions ?

Standard Sea Level Values

Pressure : 101,325 N/m²

Density : 1.2250 Kg/m³

Temperature : 288.16 K

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Objectives

To demonstrate an understanding of  the

atmosphere and its conf iguration.

Learners should evident the use of ISA and variation

of pressure, temperature and density with altitude.

Learners to demonstrate an understanding of 

subsonic f low and its parameter.

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Subsonic ?

To be Continued