BRAMWELL Helicopter Dynamics 2E

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BRAMWELL Helicopter Dynamics 2E


Preface to the second edition
  At the time of publication of the first edition of the book in 1976, Bramwell’sHelicopter Dynamics was a unique addition to the fundamental knowledge of dynamicsof rotorcraft due to its coverage in a single volume of subjects ranging fromaerodynamics, through flight dynamics to vibrational dynamics and aeroelasticity. Itproved to be popular, and the first edition sold out relatively quickly. Unfortunately,before the book could be revised with a view to producing a second edition, Bram (ashe was known to his friends and colleagues) succumbed to a short illness and died.As well as leaving a sudden space in the helicopter world, his death left the publisherswith their desire for further editions unfulfilled. Following an approach from thepublishers, the present authors agreed, with considerable trepidation, to undertakethe task of producing a second edition.
  Indeed, being asked was an honour, particularly so for one of us (GD), since wehad been colleagues together at City University for a short period of two years.However, although it may be one thing to produce a book from one’s own lecturenotes and published papers, it is entirely a different proposition to do the same whenthe original material is not your own, as we were to discover. It was necessary to tryto understand why Bram’s book was so popular with the helicopter fraternity, inorder that any revisions should not destroy any of the vital qualities in this regard.One of the characteristics that we felt endeared the book to its followers was the wayexplanations of what are complicated phenomena were established from fundamentallaws and simple assumptions. Theoretical expressions were developed from the basicmathematics in a straightforward and measured style that was particular to Bram’sway of thinking and writing. We positively wished and endeavoured to retain hisinimitable qualities and characteristics.
  Long sections of the book are analytical, starting from fundamental principles, anddo not change significantly in the course of time; however, we have tried to eradicateerrors, printer’s and otherwise, and improve explanations where considered necessary.There are also many sections that are largely descriptive, and, over the space of 25years since the first edition, these had tended to become out of date, both in terms ofthe state-of-the-art and supporting references; thus, these have been updated.Opportunities, too, have been taken to expand the treatment of, and to include additionalinformation in, the vibrational dynamics area, with both the additional and updated content introduced, hopefully, in such a way as to be compatible with Bram’s style.
  Another change which has taken place in the past quarter century is the nowgreater familiarity of the users of books such as this one with matrices and vectors.Hence, Chapter 1 of the first edition, which was aimed at introducing and explainingthe necessary associated matrix and vector operations, has disappeared from thesecond edition. Also, some rather fundamental fluid dynamics that also appeared inthis chapter was considered unnecessary in view of the material being readily availablein undergraduate textbooks. What remained from the original Chapter 1 that wasthought still necessary now appears in the Appendix. Readers familiar with the firstedition will notice the inclusion of a notation list in the present edition. This becamean essential item in re-editing the book, because there were many instances in thefirst edition of repeated symbols for different parameters, and different symbols forthe same parameters, due to the fact that the much of the material in the original bookwas based on various technical papers published at different times. As far as has beenpossible, the notation has now been made consistent throughout all chapters; this hasresulted in some of the least used symbols being changed.
  Apart from the removal of the elementary material in the original Chapter 1, theoverall structure of the book has not changed to any great degree. The order of thechapters is as before, although there has been some re-titling and compression of twochapters into one. Some of the sections in the last three chapters have been rearranged to provide a more natural development.
  Since publication of the first edition, there have appeared in the market-placeseveral excellent scientific textbooks on rotorcraft which cover some of the contentof Bram’s book to a far greater depth and degree of specialisation, and also othertexts which are aimed at a broad coverage but at a lower academic level. However,the comprehensive nature of the subject matter dealt with in this volume shouldcontinue to appeal to those helicopter engineers who require a reasonably in-depthand authoritative text covering a wide range of topics.

Sherborne                                             David Balmford
Kew                                                       George Done
2001

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BRAMWELL Helicopter Dynamics 2E

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