Aerobasics — An introduction to aeronautics 2. The atmosphere

Aircraft of all types dynamically interact with the atmosphere generate forces required for lift and propulsion. Properties of the atmosphere and their variations over geographic locations and altitude are thus relevant to aircraft flight operations. This article presents some facts about the atmosphere and indicates their relevance to flight.     

Aerobasics — An introduction to aeronautics 15. Mini and micro airplanes

There is much current interest in small unmanned airplanes weighing about five kilograms all the way down to about 100 grams. Even such small airplanes are capable of performing useful surveillance missions in peace time and during conflicts. As these airplanes operate at very low flight speeds in the range of about 10–20 m/s, their performance is strongly affected by the low Reynolds numbers characteristic of such flight. In this article, we consider the special aerodynamic and propulsion problems associated with the flight of such small airplanes.     

Aerobasics — An introduction to aeronautics

Flight at supersonic speeds is accompanied by standing waves, a phenomenon absent in subsonic flows. The standing waves affect the flow radically and lead to wave drag and sonic booms. In this article, we explain the above phenomena and their effect on the performance of airfoils and wings in supersonic flows. In the light of the above, wing configurations suitable for supersonic airplanes are discussed.