AEROSPACE PROPULSION FROM INSECTS TO SPACEFLIGHT Ulf Olsson Volvo Aero Corporation Vice president Technology (ret) - 2 - Olsson,Ulf Aerospace Propulsion from Insects to Spaceflight Copyright © 2006 by Volvo Aero Corporation. 1st Edition 2006 published Heat and Power Technology, KTH, Stockholm, Sweden. 2nd Edition April 2012 PREFACE This book is an introduction to the theory and history of aerospace propulsion. It describes how this specific technology has reached its present form and how it may develop in the future. To understand the technical parts, the reader is assumed to know about thermodynamics and aerodynamics at university level but no prior knowledge of aerospace propulsion technologies is required. For those wishing to go directly to the mathematics, a number of calculation schemes are given in the text as Appendices to various Chapters. They make it possible to write computer programs for performance estimates of the various types of engines. A number of exercises are included at the end of the different chapters. Solutions to the examples are provided in a separate Chapter at the end of the book together with the relevant equations being used. This can be used as a short handbook to the most important equations. For the reader specifically interested in the history of propulsion, a separate guide to the main topics and the most famous names is given under Contents below. Historical notes are also underlined in the text to be easily located. Ulf Olsson April 2012 ii iii CONTENTS Preface 0. Introduction Page 1 1. The balloons lighter than air 5 2. Newton and the reaction force 11 3. Insects – the lift of wings 20 4. Birds lift-to-drag 36 5. Micro Air Vehicles the need for power 53 6. The evolution of the fixed wing aircraft 79 7. The golden age of the propeller 101 8. The jet engine arrives 141 9. The bypass engine and the revolution in air travel 180 10. Economy and ecology as new limits 207 11. The future civil aircraft 235 12. The thermodynamic design of a civil jet engine 268 13. Turbo machinery design for the civil jet engine 306 14. Advanced cycles 355 15. Military aircraft 388 16. Design of a military engine 409 17. Off design and variable cycles 444 18. The limits of the turbojet engine 478 19. Ramjets and scramjets 518 20. Rocket engines 545 21. Combined engines 575 22. Rockets and spaceplanes 598 23. Interplanetary flight 620 24. Future propulsion systems 654 25. Answers to the exercises 681 Further reading 704 iv Appendices Page 11. Civil aircraft 265 12. Thermodynamic design of a New Civil Engine 299 13. Mechanical design of jet engines 343 14. Advanced cycle engine 384 15. Military aircraft thrust requirements 407 16. Military engine design calculations 436 17. Off-Design of a military engine 472 18. Turboramjet calculation scheme 506 Equations for the performance of ramjets, scramjets and pulse detonation engines are given in Chapter 19 and for rocket engines in Chapter 20. Performance estimates for combined engines for spaceplanes are treated in Chapter 21. v Historical Notes Man's passion to fly….prehistoric times Page 1 The 21st of November 1783...the Montgolfiers 5 The reaction principle 1687…Newton 11 Insects..300 million years ago 21 Hydrodynamics...1738...Daniel Bernoulli 25 Birds.. a 60-million year history 37 The first attempt to fly...a Roman magician 54 Leonardo da Vinci .. 56 The first flapping machines … the 1870s 57 Bats and the Micro Air Vehicles 60 Studies of birds..law of two-thirds 65 Pteranodon....the lifting wing 73 George Cayley …inventing the aircraft 1799 80 Early pioneers ….Henson & Stringfellow 81 Royal Aeronautical Society... 1866 83 Otto Lilienthal experimenting with wings 84 Orville and Wilbur Wright 1903 91 The propeller…an old invention 94 About 1660, the internal combustion engine 95 Charles Lindbergh landed at Le Bourget 1927 101 The first commercial airline 1910 in Germany 103 Joukowski….basic studies of wings 106 Ludwieg Prandtl …the aeronautical scientist 108 “The Spirit of St. Louis" 115 Amelia Earhart first woman over the Atlantic 118 In the 1930’s, the aircraft reached its present form 120 Adjustable propeller blades… Frank Caldwell 128 Isaac Newton …the speed of sound 132 James Prescott Joule …forms of energy 133 The Mach number is named after Ernst Mach 138 vi Supersonic jets … in 1888 de Laval 141 Aegidus Elling ..first successful gas turbine 149 Frank Whittle …first patent of a jet engine 1930 153 First jet aircraft 1939 ....Hans von Ohain 154 Adolf Busemann … sweptback wings 170 1947, Chuck Yeager..the sound barrier 173 The area rule..Richard Whitcomb 174 How speed has developed over the years 179 The bypass engine …Gerhard Neumann 180 The turbofan caused a revolution in aircraft size 201 The civil aviation industry has grown rapidly 208 The noise levels have been substantially reduced 232 The fuel consumption of aircraft has decreased 236 The efficiency of jet engines has more than doubled 241 The maximum L/D has stagnated at below 20 251 Isaac Newton…aerodynamic drag 252 Turbine inlet temperatures has increased very much 290 Aiming for stealth, unmanned and thrust vectoring 388 Engine thrust-to weight ratio has tripled 411 The first active study of a supersonic compressor 499 Rene Lorin in 1913 ..ram pressure for propulsion 519 The pulsejet invented in WWII 519 The scramjet concept was invented in the late 1950s 531 Rockets first used in China 1232 545 The liquid rocket engine 1926 Robert H. Goddard 550 Tsiolkovsky proposed…space exploration by rockets 599 Wernher von Braun the V2 1942 603 The spaceplane concept is not really new 608 Spaceflight started…in 1959 623 Isaac Newton and his concept of gravity 625 Nuclear rocket engines 638 Electrical engine systems 641 vii 0. INTRODUCTION The passion to fly must have originated in prehistoric times. Stories of the flight of men, animals, and Gods abound in the myths, art, and religions of ancient civilizations and the magical ability to fly was often attributed to the Gods. Oriental and Western folklore abound with stories of magic carpets, witches on broomsticks, and other forms of movement through the air. As far back as 3500 BC the Babylonians engraved on semiprecious stones the adventures of Etana, a shepherd who flew on the back of an eagle. The legendary Chinese prince Ki Kung-shi flew a flying chariot and the Persian king Kai Ka'us, a flying throne. Khonsu was a winged Egyptian God and Assur, the main 2 Assyrian God, had an eagle's wings. In Arabic folklore a magic carpet glided over Baghdad, in a Greek myth Bellerophon rode Pegasus, the flying horse and in Roman mythology Mercury was the winged messenger of the Gods. The best known ancient legend on the subject of flight is that of Daedalus, the engineer who built the labyrinth on the island of Crete in which the Minotaur lived, having the body of a man and the head of a bull. Daedalus was imprisoned by King Minos together with his son Icarus, but they escaped by making themselves wings of wax and feathers. With these Daedalus flew successfully all the way to Naples, but Icarus, excited by the thrill of the new experience, let his youthful exuberance deafen him to his father's warnings. He flew too close to the sun, which melted the wax and sent the boy crashing to his death in the sea below. Long before men learned how to fly, they sent objects soaring through the air. The arrow dates from the Stone Age and the ancient Chinese flew kites. The early inhabitants of Australia invented the boomerang, with blades carved in the shape of an airfoil. However, it took a long time before technology had advanced sufficiently to make the dreams of human flight come true. Then in 1783 the first men took to the air in a balloon using a principle first discovered by Archimedes two thousand years earlier. The balloons would reign the skies for more than a century but in the end it was the reaction principle giving thrust and lift from the accelleration of a jet that made controlled flight possible in a large scale. Isaac Newton´s equation for the the thrust of a jet is therefore one of the most important equations in history. 3 The first manmade object using the reaction principle for flight was the rocket invented by the Chinese some time before the 10th century. Long before that the insects had learnt how to fly using the reaction principle blowing an air flow downward by their flapping wings. Over many centuries, numerous attempts were made by daring adventurers to fly like insects and birds but the necessary power was much more than that of a man. A breakthrough came with the discovery in the beginning of the 19th century of the lifting wing of the birds. This made it possible to separate lift and propulsion producing lift without flapping. From then on the main problems were to understand how the wings worked and to develop engines with sufficient power. It was not until in 1903, that man could make machines as powerful as a bird and the Wright Brothers could make their first flight using an internal combustion engine powering a propeller. The propeller soon gave way to the jet engine and during the 20th century, air and space transportation grew into one of the world’s most important industries. Modern society is inconceivable without it and it is an essential part of economic development. It is now possible to travel across the globe in a matter of hours rather than the weeks or months of fifty years ago.