1. Unit 2 BASICS OF FLIGHT MECHANICS
Physical properties and structure of the atmosphere, temperature, pressure and altitude relationships
Newton’s law of motions applied to aeronautics –
Aircraft Axis system- Motions of Aircraft with respect to the axis system –
evolution of lift, drag and moment.
Nomenclature of aerofoil, classification of Airfoils-NACA aerofoil, Mach number, maneuvers.

2. Physical properties and structure of the atmosphere, temperature, pressure and altitude relationships

3. Atmospheric Circulation
Moving things around on present day Earth

4. Wind is a moving air or flow of gases on a large scale
WINDS
Wind is a moving air or flow of gases on a large scale

5. Definition of wind
The horizontal movement of air along the earth surface is called wind. The vertical movement of air is known as air current. Wind and air current together comprise a system of circulation in the atmosphere.

6. Causes of winds Pressure gradient-pressure force
Rotation of the earth-coriolis force
Friction of the earth-velocity of the wind -

7. Types of winds Permanent or planetary winds or prevailing wind
Trade/Westerlies/polar wind
Periodic winds or local wind
Sea/land/moonson

8. Atmospheric circulation
Powered by sunlight – uneven solar heating
About 51% of incoming energy is absorbed by Earth’s land and water
Energy absorption varies depending on the angle of approach, the sea state and the presence of ice or other covering

9. Atmosphere The gaseous envelopes surrounding the earths surface.
Pressure and temperature play an extremely important role in the performances of airplanes.
The critical elements is air density which decreases as pressure falls and temperature rises.

10. The aerodynamic qualities of the airframe depends upon air density .
If the air density decreases, then aerodynamic qualities decreases.
High temperature and low pressure cause a decreases in air density.
The atmosphere consists of mixture of gases that surround the earth and held to it by the force of gravity.

11. For this reason, the atmosphere is denser near the earths surfaces and the air density decreases as height is gained.
Since both engine and aerodynamic performance depends on air density they also decrease with altitude.

12. The mixture of gases that we call air consists mainly on nitrogen and oxygen and water vapor.

13. Composition of the atmosphere
78% nitrogen and 21% oxygen
Other elements make up < 1%
Air is never completely dry and water can be up to 4% of its volume.

16. Atmospheric Structure

17. Troposphere Close to earth surfaces Up to 10 km
Turbulent condition of air
Temperature decreases

18. Stratosphere It extends from troposphere to about 50km
Highest velocity but no gusty flow
Temperature remains constant up to about 25km and then temp Increases

19. Mesosphere It extends from Stratosphere to about 80km
Temperature decrease
Pressure and density of air very low

20. Mt. Everest
(8,850 m)

21. Structure of the Atmosphere
Troposphere is densest and is where our weather occurs
Substances in the stratosphere persist for long periods because there are few removal processes
In troposphere, temperature decreases with altitude
In stratosphere, temperature increases with altitude due to interactions with particles and radiation from the sun
The ozone layer is within the stratosphere

22. PHYSICAL PROPERTIES- Pressure
If the aircraft sense the actual outside air pressure which corresponds to a certain standard altitude, then that altitude is called pressure altitude.

23. PHYSICAL PROPERTIES- Density
If the aircraft sense the actual outside air density, which corresponds to a certain standard altitude, then that altitude is called density altitude.

24. PHYSICAL PROPERTIES- Temperature
If the aircraft sense the actual outside air temperature, which corresponds to a certain standard altitude, then that altitude is called temperature altitude.