**.&• 44?. The Art of Soaring Flight iV WOLF HIRTH Translated from the German by \aomi Heron-Maxwell Befr. 32 319 (1239) WOLF HIHTII Translation of the work ..Die Hohe Schule des Segelfluges by Wolf Hirth_ Copyright 1938 by Wolf Ilirth, Vaihingen-Stutl^art. / Printed in Germany by Stuttgarter \Yreinsbnchdruckerri AG.. Stuttgart. Editing and advertising By G.(fi.^.Wienfi<4i.Moehringen-Stuttgart Dedicated to the memory of Eric Collins and AY arren Eaton Index page Preface . ........ ........ 8 Translator's Note ..... ........ 9 Introduction ..... .............. 10 1. A few Remarks on Fly ing . 12 Steep Turns by Ludwig Hofmann ......... 13 2. Sailplanes and their Instruments Instruments ............... 17 Sailplanes ............ ...... 20 3. Storm-Riding 23 My first thunderstorm flight by Robert Kronfeld . 24 Some Remarks by Wolf Hirth ... ...... 28 4. Thermal Soaring The Formation of Thermals . ... 34 Day Thermals ...... .... ... ."> > Direct Sun Thermals ......... ..... .'So Winter Thermals ...... ......... 48 Evening Thermals ........ ....... .~>1 Wind Thermals ....... ....... .~>.'S Flying High by Wolf Hirth ........... -",4 Thermal Soaring by Ludwig Hofmann ....... ."V) More Soaring Flights with particular reference to aero-towing by Peter Riedel ... .... (>2 Motorless from the Rhdn across the Rhine and as far as the Moselle by Wolf Hirth ... .... 68 5. C 1 o u d F 1 y i n g ........ .... ?4 How I practised blind-flying by Ludwig Hofmann . 78 Cloud-Flying in the 1932 Rhdn Competitions by A. Mayer ................. 79 An interesting Cloud-flight by Wolf Hirth ... 86 169 Miles across-country (1935) by W. Spate ... 89 Heini Dittmar's World Altitude Record in South America ... ......... .... ( *2 A Cloud thermal flight by Dr. A. K. Slater . 93 How I was flung out of a sailplane while cloud-flying by Rudi Patz ...... ..... 98 More Cloud Flights ........ ...... 102 Lift Clouds . ............. 1(U 6. Local Thunderstorms My Soaring Flight in a Local Thunderstorm by Heinz Huth . .\ ..... ......*. 105 Hofmann's Flight through four local thunderstorms by G. Brutting .... ... .... 108 7. The Long Wave The Secret of the Moazagotl by \Volf Hirth 110 Lenticular Clouds by V. E. Slater ... 113 8. Me thods o f Laun eh i n g . 116 9. Acrobatic s .. ...... 118 10. A short Survey o f S o a r i n g in B r i t a in by A. V. Slater 118 Eric Collins by A. E. Slater ...... .124 104 miles A British Distance Record by P. A. Wills 128 A Thunderstorm Flight by J. S. Fox ... 131 A Climb in a Cloud by P. A. Wills . 13+ Going West by P. A. Wills . ....... 137 11. A shortSurveyofSoaringin America by A. E.Slater 143 Warren Eaton by A. E. Slater ...... ... 1+5 The Longest Ridge Soaring Flight by L. B. Barringer 146 Distance over the Plains by L. B. Barringer .... 151 12. Soaring expedition to South Africa Oct. Nov. 1936 by P.A.Wills . .............. .158 13. Some young German Sailplane Pilots by Georg Brutting Ludwig Hofmann ..... .160 Heini Dittmar . ... ... 163 Hanna Reitsch ..... ........... 165 My Beginnings as a Soaring Pilot by Martin Schempp 166 14. More Soaring Flights by Gcorg Brutting . 169 My Goal-Flight: Hornberg Cologne (206 miles) by Erwin Kraft ..... ... 172 15. A Glimpse intothe future by Wolf Hirth From Glider to Powered Sailplane ........ 175 How far can the standard of Soaring be raised by Man's Skill alone? . ' 180 Conclusion ...... .......... ...182 List of British Gliding Clubs and their Secre­ taries .......... ...... .18+ Bibliography compiled by A. E. Slater ... 187 Preface In many countries, there are today a number of sailplane pilots, who fly well and have good machines and yet arc not sufficiently knowledgable and experienced to make full use of all the soaring possibilities at their disposal. Here and there much valuable in­ formation lias, it is true, appeared in various publications; but it is difficult for the beginner to pick and choose That is why this little book has been written. It is a guide to those who are anxious to be initiated into the secret * of soaring: the sublime, silent flight of the birds, the finest sport of all. I have purposely refrained from dwelling at length on the mechanics and meteorology of flight, but have stri\cn to give the student of soaring flight a clear explanation of all that must necessarily be of interest to him or her. However, in order fully to understand this book, readers will find it advantageous to possess a little rudimentary knowledge, and suggested reading matter is appended. Wolf Hirth Translator's Note During the past few years soaring flight in Great Britain and America has made rapid strides; but many enthusiasts have, 1 think, like myself, been severely hampered by the lack ol available litera­ ture. For a long time I could only gain a limited theoretical know­ ledge by means of verbal discussions, and when at last I had the good fortune to meet Wolf Ilirth personally and read "The Art of Soaring Flight" in the original, a new world was opened up to me. Wolf Hirth needs no introduction as one of the pioneers of soaring flight, and in this work he has given to the \\orld the result of his accumulated experience. \\ hen. therefore, he asked me to translate it into English, I was only too delighted to do so and thus give others the opportunity of learning from one who had already taught me so much. No student of soaring flight can ever hope to achieve success without an understanding of certain meteorological phenomena, which are clearly explained in this book, and I feel that the reader will find every page both instructive and stimulating. Soon after the original was published, it was translated into Polish, and it may be truly asserted that this was a considerable factor in placing Poland second only to Germany in the realm of motorless flight: at any rate, its immediate result was the acquisition of 19 Polish "Silver C's" within the year of its publication. In conclusion, I would like to thank all those who have so kindly assisted me in my work as translator, in particular the following: Dr. A. E. Slater, the well-known Editor of the "Sailplane and Glider", and Mr. P. A.\\ ills for their important contributions: Mr. J. S. Fox and Ilerr K. Schlichting for their useful assistance in certain chapters; Mr. L. B. Barringer for his initial work in the translation; and finally Mr. F. C. H. Alien for his untiring patience and invaluable help in the preparation of the whole book: without his aid it is doubtful whether I would ever have been able to complete my task. Naomi Heron-Maxwell. 9 Introduction The very earliest pioneers visualised in soaring. a> we know it today, the solution of the problem of flight. There was Leonardo da Vinci the renowned artist and scientist 500 years ago, Berhlinger the tailor from Llm 100 years ago. and Lilienthal the engineer 50 years ago. The strength of the human body had proved inadequate to maintain flight, and light engines did not then exist. Yet, as some birds ap­ parently had no difficulty in flying long distances at high altitudes, it was thought that the secret of their flight must lie in the air itself. All these first soaring theorists believed in the truth of this, and among them was Lilienthal, who became not only the first actually to fly, but also the first to succeed in soaring, by allowing himself to be borne aloft by a breeze blowing up a hill. Then came the internal combustion engine and its subsequent adaptation to aeroplanes; but the idea of motorless flight remained. Mere and there new and more accurate soaring theories were evolved. Meteorologists had already discovered the existence of air-currents, which might be utilised, and their real value was soon to become actually demonstrable under the influence of the rapidly growing knowledge in both aerodynamics and the technique of flying. In the year 1920, hill-soaring was revived on the Rhon on more or less the same lines as Lilienthal s early efforts, but this time with wider aims in view. The Rhon Mountains form a mighty barrier over which Westerly winds must always climb, as they cannot flow round them. Over the West slope, therefore, there lies a belt of air rising right up over the ridge, many million times greater in volume than the region of slope-currents over Lilienthal's historic site. But in 1920 even this belt of rising air proved insufficient to keep sailplanes aloft. At that time, great hopes were centred round the possibility of dynamic flight, for which the gustiness of the air might be used to enable these "dynamic" sailplanes to fly as far as desired: but people soon realised that this idea was impracticable. However, it was not long before pilots were not only to be practising a new art called 'hill-soaring" but also to be flying from one hill to another by utilising various soaring sites, which branched out in all directions from the Rhon for a distance of 15 20 miles. 10 the topography of which had been carefully mapped by the scientific leaders of the soaring movement. When, one day, a sailplane pilot was actually carried 30 miles away from these hills by a thunderstorm, it was seen thai a new avenue was opened up to the enthusiasts and soon several pilots were making regular use of this form of cross-country flying. Before long still further soaring possibilities were discovered. With the help of meteorological information, by observing soaring birds and by using instruments, sailplane pilots began to find and make use of upcurrents in all kinds of weather conditions and over the most varied tracts of country.