Henk Tennekes has a second edition of his book, and I am pleased to announce it on my weblog. Following the announcement, Henk has also provide a review of another book that he has completed.
“The Simple Science of Flight: From Insects to Jumbo Jets (Revised and Expanded Edition)” by Henk Tennekes
From the smallest gnat to the largest aircraft, all things that fly obey the same aerodynamic principles. In The Simple Science of Flight, Henk Tennekes investigates just how machines and creatures fly: what size wings they need, how much energy is required for their journeys, how they cross deserts and oceans, how they take off, climb, and soar. Fascinated by the similarities between nature and technology, Tennekes offers an introduction to flight that teaches by association. Swans and Boeings differ in numerous ways, but they follow the same aerodynamic principles. Biological evolution and its technical counterpart exhibit exciting parallels. What makes some airplanes successful and others misfits? Why does the Boeing 747 endure but the Concorde now seem a fluke? Tennekes explains the science of flight through comparisons, examples, equations, and anecdotes.
The new edition of this popular book has been thoroughly revised and much expanded. Highlights of the new material include a description of the incredible performance of bar-tailed godwits (7,000 miles nonstop from Alaska to New Zealand), an analysis of the convergence of modern jetliners (from both Boeing and Airbus), a discussion of the metabolization of energy featuring Lance Armstrong, a novel treatment of the aerodynamics of drag and trailing vortices, and an emphasis throughout on evolution, in nature and in engineering. Tennekes draws on new evidence on bird migration, new wind-tunnel studies, and data on new airliners. And his analysis of the relative efficiency of planes, trains, and automobiles is newly relevant. (On a cost-per-seat scale, a 747 is more efficient than a passenger car.)
About the Author
Henk Tennekes is Director of Research Emeritus at the Royal Netherlands Meteorological Institute, Emeritus Professor of Meteorology at the Free University (VU) in Amsterdam, and Emeritus Professor of Aerospace Engineering at Pennsylvania State University. He is the coauthor of A First Course in Turbulence (MIT Press, 1972).
|“This was a great little book when it came out in its original edition; this new version is even better, as it contains both Henk’s homage to his favorite flying machine (Boeing 747) and explanations based on some of the unexpected results of recent experiments with bird flight (including a phenomenal gliding jackdaw). Read it, then watch the birds and planes, and then dip into it again and again.”
–Vaclav Smil, University of Manitoba, and author of Global Catastrophes and Trends”
One gets a fine sense of how so much of aircraft design-whether by humans or by evolution-depends on size and mission. This new version of The Simple Science of Flight broadens the enlightenment that so many of us found appealing in its predecessor. It yields even more of that satisfying ‘now I understand what’s happening’ rather than the usual ‘how brilliant those designers must be.’ And I know of no book that derives such an awesome wealth of insight from such simple quantification. Beyond being informative, it provides pleasant reading-for any one who travels by air, watches animals fly, or dreams of learning to fly.”
–Steven Vogel, James B. Duke Professor, Emeritus, Duke University
Review By Henk Tennekes
Alexander’s Jumbo Jets
Alexander, David E. 2009. Why Don’t Jumbo Jets Flap Their Wings? Rutgers University Press. ISBN 978-0-8135-4479-3, hardback, 278 pp, figures. Price 28 euro.
David Alexander is the author of Nature’s Flyers (2002), a deservedly popular introductory biology text on flying insects, bats, and birds. Rutgers University Press recently released Alexander’s second book, Why Don’t Jumbo Jets Flap Their Wings? The new book is written for the general public, not primarily for professional biologists and engineers. “Science writing at its best,” says professor Sankar Chatterjee of Texas Tech, and I agree. This book is intended for birdwatchers who, like me, are fascinated by everything that flies, natural or technical.
In ten easygoing and enjoyable chapters, focussed on the differences between flying animals and airplanes, Alexander deals successively with evolution, lift, power, manoeuverability, the need for tail surfaces, flight instruments, soaring, hovering, aerial combat, and ornithopters. One major point of divergence: muscles excel in back-and-forth motion such as wing flapping, aircraft engines base their functionality on rotary motion. As far as manoeuverability is concerned, the sophisticated interaction between their nervous system and their flying apparatus that insects, birds, and bats are capable of is a source of envy for pilots and aircraft designers. Bats have no need for tails because their nervous systems are so well integrated. The chapter on predation and aerial combat is a real treat. I knew of course that Eleanora’s falcon feeds on migrating passerines during its breeding season, but I didn’t know that the greater noctule bat does so too, taking advantage of the fact that most passerines are nocturnal migrants. And I was thrilled to learn that some insect-hawking bats “use their wings as tennis rackets, deftly tapping an insect to deflect it into their mouths.” Alexander deals at length with ornithopters. Considering the title of his book, he has to. Flapping wings are not the way to go when size and weight become too large. A jumbo jet does not flap its wings because the hinges, engines, and linkage systems needed to power it would be far too heavy. Also, flapping flight is like a roller-coaster ride, because the upstroke of the wings delivers little or no lift, so that the body falls until lifted again by the downstroke. All passengers riding a flapping jumbo jet would be airsick for the entire ride. On the other hand, flapping is the preferred solution when sizes are small. Miniature rotary engines cannot compete in that technological niche.
Alexander compares the slow evolution of flight in Nature with the rapid evolution of flight in human technology. “Natural selection works on a time scale of hundreds of thousands or even millions of years. When a one-in-a-million beneficial change does occur, it tends to spread through the species. Changes that might take hundreds of thousands of years of animal evolution can take place in less than a decade of technological development.” He recognizes other differences, too. Animals co-evolve with their environment, human technology often changes the environment. Wheels are unsuitable in rough terrain; the worldwide success of automobiles is due in no small part to the concurrent evolution of highway systems. I feel Alexander tends to underestimate how often technological breakthroughs resemble random genetic mutations in Nature, which, as he correctly states, are “almost always detrimental.” Airplane encyclopedias are filled with planes that can fairly be labeled as evolutionary misfits, as designs that did not live up to their designers’ dreams and disappeared within ten or twenty years. Some, like Howard Hughes’ Spruce Goose made just one brief hop. Others, like the supersonic Concorde, are evolutionary mutants, products of the overheated preoccupations of their designers and sponsors. Even the ultimate aeronautical dream, human-powered flight, lovingly described in Alexander’s book, did not last long. Planes powered by human athletes are unfit for everyday use; they are in fact extinct now.
In the epilogue, Alexander returns to the central theme of his book: how flying animals differ from flying machines. “In the end, what truly sets birds apart from airplanes is versatility versus efficiency. Engineers design airplanes to carry out particular tasks, so airplanes tend to be quite specialized. A Boeing 747 can haul huge loads of passengers over enormous distances, but that is basically all it can do. Animals cannot afford to be so specialized.” I agree, but not without some reservations. Albatrosses are specialized in so-called dynamic soaring in wide-open environments with a uniform wind regime, bar-tailed godwits perform 11,000 km nonstop flights across the Pacific Ocean but have a barely adequate immune system, bats use very sophisticated echo location equipment that is useless in daylight because insects can easily take evasive action, penguins use their wings exclusively for under-water swimming, and so on. And some kinds of airplanes, like the Piper Cub and the Cessna 172, are supreme generalists, much like sparrows and starlings. In fact, the early success of the Piper Cub was based on its usefulness for the US Army: it could land and take off most anywhere, rough terrain or not. The task of evaluating the differences between biological evolution and its technological counterpart is far from being finished, but in Jumbo Jets Alexander makes a giant step in the right direction.