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The aim of this paper is to study the effect of pressure angle and helix angle on bending stress at the root of helical gear tooth under dynamic state. Gear design is a highly complex process. The consistent demand to build low-cost, quieter and efficient machinery has resulted in a gradual change in gear design. Gear parameters such as pressure angle, helix angle, etc. affect the load-carrying capacity of gear teeth. Adequate load-carrying capacity of a gear is a prime requirement. The failure at the critical section because of bending stress is an unavoidable phenomenon. Besides this fact, the extent of these failures can be reduced by a proper gear design. The stresses produced under dynamic loading conditions in machine member differ considerably from those produced under static loading.

The present work is intended to study the effect of pressure angle and helix angle on the bending stress at the root of helical gear tooth under dynamic state. The photostress method has been used as experimental methods. Theoretical analysis was carried out by velocity factor method and Spott’s equation. LS DYNA has been used for finite element (FE) analysis.

The results show that experimental method gives a bending stress value that is closer to the true value, and bending stress varies with pressure angle and helix angle. The photostress technique gives clear knowledge of stress pattern at root of tooth.

The outcomes of this work help the designer use optimum weight-to-torque ratio of gear; this is ultimately going to reduce the total bulk of the gear box.

Aircraft manufacturers now demand wheels which are not only light but also have a long life capability. A typical civil aircraft project such as the Boeing 757, requires a fully approved wheel with a demonstrated life of 50,000 roll miles which equates to approximately 10,000 landings.

In recent times technology has been advancing at an unprecedented pace and there has been an equally unprecedented demand to learn about it at all levels from the popular to the most advanced. In times past this interest would have been satisfied by a relatively small number of lectures, followed in due course by one or two carefully prepared text books which would endure for many years.

The title of this volume is one that should bring an eager sparkle to the eyes of your aerodynamic friends. Both turbulence and heat transfer are topics of major practical importance, and for engineering purposes they share a common basis of empiricisms, regarded with justifiable suspicion by fundamental research workers, but on which useful working formulae have been developed. Meanwhile, the said research workers have pursued thoroughgoing scientific investigations into the phenomenon of turbulence and although as yet no important practical applications appear to have resulted from their work they have built up a body of knowledge which has its own intrinsic value and which will undoubtedly have important applications in the future. Good books on these topics are very rare, hence the interest which this title will arouse in aerodynamic circles. An optimist will expect the book to provide him with a complete and ordered survey of both the fundamental and applied lines of development, with appropriate critical comments, and he will expect to find the answers to many of the current problems with which he may be concerned. His expectations will not be entirely fulfilled, the arrangement is not as well ordered as it might be and the writing was largely completed in 1956, so that more recent developments and problems are not dealt with. Such defects are however inevitable in a collection of articles of this kind dealing with a rapidly developing group of subjects, and there is much of value in the book.

THE major problems concerning aircraft tyre design are the high ground speeds involved, very high braking torques which have to be transmitted, high temperatures which can be generated in the brakes and transferred to the tyres, as well as the stringent weight and space limitations imposed. These problems have all been magnified many times through the years with the great increases of aircraft speed and weight: modern jet airliners having ground speeds of up to 250 m.p.h.

THE AIRCRAFT MANUFACTURER can provide helpful answers to the two most important questions of the communities affected by air transportation. Aircraft will be built which do not intrude on the every day existence of communities. Aircraft will be built whose airports only require tens of acres of land instead of thousands of acres. The DHC‐7 will be the first of them.