Aerobasics — An introduction to aeronautics

Modern aircraft are designed for the utmost in performance and safety as the penalty for any shortfalls in these areas is very heavy. Thus they incorporate many complex systems and subsystems, each developed using advanced scientific concepts and manufacturing methods. Aircraft design is undertaken by a group of design engineers, each with a specialized knowledge about a few subsystems but only a rough understanding of the whole aircraft. This rough overall understanding of the concepts and principles based on which an aircraft is organized is a vital element of a design engineer’s toolbox. It helps him perform his own specialized task such that it fits in the complete design seamlessly. This comprehensive knowledge is not easily acquired from modern technical literature which is voluminous and primarily caters to special interest groups. An attempt has been made here to gather this knowledge and present it concisely as a series of articles, so that it will serve as a broad general introduction to aircraft engineering. This material should be useful not only to fresh engineers entering the aeronautical industry but also to students in all relevant branches of engineering. It is also likely to be of general interest to any scientifically inclined reader as a source of basic information in a number of aeronautical disciplines. The general philosophy adopted here is best summarized by the following quote from the Panchatantra: “Knowledge indeed is unlimited, but life is short and there are many obstacles to the acquisition of knowledge. Therefore one must grasp the essential knowledge leaving out much detail ….”     

Aerobasics — An introduction to aeronautics

This article introduces the concepts of lift and drag of a wing and their role in determining the performance of an airplane. The airplane is then compared with other modes of transport on the basis of a study by Gabrielli and Von Karman to bring out its special features. Next, the requirements of controlled flight are explained. The relations between the configuration of the airplane and the requirements of controlled flight are indicated.     

Aerobasics — An introduction to aeronautics

This part of the article continues the discussion of the aerodynamic characteristics of airfoils presented in the previous part and extends it to wings at subsonic speeds. The effects of highlift devices and spoilers are considered and their application indicated. The effects of wing sweep and finiteness of aspect ratio are analyzed.     

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.     

Aerobasics — An introduction to aeronautics

A study of air flow past simple bodies provides a background for the understanding and interpretation of aerodynamic forces on airplanes. In this article some simple flows are studied by treating air as a viscous and compressible fluid subject to the laws of mechanics. The importance of two dimensionless parameters, the Reynolds number and the Mach number, respectively representing the viscous and compressibility effects is clearly brought out. The different flow phenomena associated with specific ranges of the Reynolds and Mach numbers are indicated and explained.     

Aerobasics — An introduction to aeronautics

An airplane needs a propulsive device to overcome drag. A piston engine driven propeller was the first solution to this problem and was developed rapidly during the early days of aeronautics. The jet engine was invented during the Second World War and quickly replaced the piston engine which is now used only on very small aircraft. Variants of the jet engine were later developed to improve the performance and economy. Currently the burbofan or bypass jet engine is the dominant type of engine in use. The turboprop is a variant which is suitable for lower flight speeds. In this article we describe the general principles of operation of the different propulsive devices and indicate the range of flight conditions. All engines are noisy during operation. Noise is annoying and affects a large number of people on the ground near airports. Considering this, a small section on engine noise is included at the end.     

Aerobasics — An introduction to aeronautics

Aerodynamic forces and moments on an airplane configuration under various fight conditions are of primary concern in aeronautics. These are best understood by first studying the forces/moments on simple body shapes which go towards constituting the airplane configuration. In this article, we study the aerodynamic properties of some simple body shapes indicated by the terms bluff bodies, streamlined bodies and airfoils.     

Aerobasics — An introduction to aeronautics

Performance of an airplane defines its usefulness and is the primary reason for designing and manufacturing aircrafts. In this article we present simple methods for approximately evaluating the performance of an airplane in normal and accelerated flight conditions. Methods are presented for calculating maximum and minimum flight speed, maximum flight altitude, endurance range, etc. Some flight conditions involving acceleration like take-off, landing, pull-ups and turns are also considered.     

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 12. Safety in aviation

Public awareness of airplane safety is very high due to the spectacular nature of airplane accidents. Partly as a result, civil airplane operations are tightly regulated at all levels from design to operation and maintenance. Scheduled airline operations have thus been able achieve a very high level of safety. In this article we quantify the safety of flight operations and indicate the design concepts like fail safety and safe life used in achieving a high level of safety. As an illustration, we consider the safety of a flight of a twin engine airplane in the event of one engine failure.     

An introduction to word–formation

<正>A word is a free form which doesn’t consist entirely of lesser free forms.In briefly,a word is a minimum free form.You may be curious about how the words are formed.Let’s study the rules how words are formed step by step.1.Onomatopoeic words The words which represent sounds or things that make a     

Aerobasics — An introduction to aeronautics 14. Air navigation principles

Air navigation has evolved over the last hundred years from an art into a mature science. Airplane accidents due to navigational errors are practically nonexistent. In large measure this advance has been due to radio aids to navigation which operate under all weather conditions. However in remote areas and in hostile airspaces, the radio aids may not be available and a fully self contained navigational device is required. Navigation by stars (celestial navigation) is feasible under such conditions. But the inertial navigation system (INS) is the preferred choice. In recent times, a navigational instrument based on radio communication with specially designed satellites in low Earth orbits called the global positioning system (GPS) has become popular. This article deals with the principles of these various methods of air navigation.     

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.     

An introduction to multiple perspectives on Davydov’s approach in the XXI century

Educational Studies in Mathematics -     

Q‐methodology in communication science: An introduction

Q‐methodology, traditionally a tool for phenomenological analysis, single‐subject or small sample research, and typological analysis, has potential for research in human communication. Unfortunately, q‐techniques have often been neglected or misunderstood by main‐stream social scientists. This article presents basic information regarding the construction of q‐sorts, discusses methods for analyzing q‐sort data in a variety of research contexts, and identifies resources which may be consulted by those wishing to learn more about the method.     

What Is the Queer——An Introduction to Queer Theory

Queer theory,as a field of post-structuralist critical theory that emerged in the early 1990s out of the fields of queer studies and Women’ s studies,is now receiving more and more academic attentions.This paper gives an introduction to its definition,theorists,basic premises as well as its literary applications,aiming to shed some light on this seemingly "queer" theory.     

Matrix models — An approach to understand complex systems

Matrices with random matrix elements appear to have applications in physics, mathematics, biology, telecommunications, etc. In fact, experimental data of many complex systems, such as the spacing distribution of energy level spectra of heavy nuclei, and the distribution of the nonreal zeros of the Riemann zeta function can be reproduced using the theory of such matrices. In this article, we present the integral calculus of matrices with random matrix elements which will provide the necessary foundation to study their applications. In particular, we will present in detail an elegant and systematic tool called Feynman’s method to perform integration of matrices.     

Using SAS® PROC CALIS for path analysis: An introduction

This article presents a straightforward approach for using PROC CALIS programs that will perform path analyses using observed variables. The step‐by‐step approach should help the beginner understand concepts in path analysis and how to use the SAS^® System's PROC CALIS procedure. The approach begins with the development of a program figure, a figure that graphically illustrates the researcher's theoretical model and identifies the parameters to be estimated in the model. A set of 14 rules guide this task. The article illustrates how to convert the program figure into a PROC CALIS program that will estimate parameters in the diagrammed model and how to review the output of PROC CALIS (e.g., residuals, chi‐square test, fit indices) to assess the fit of the model to the data.