Spinning Flight: Dynamics of Frisbees, Boomerangs, Samaras, and Skipping Stones

Spinning Flight: Dynamics of Frisbees, Boomerangs, Samaras, and Skipping Stones , Ralph D. Lorenz , Springer, New York, 2006. $49.95 (346 pp.). ISBN 978-0387-30779-4

Consider the following natural phenomena: The seed of a sugar maple tree spins as it falls to the ground, autorotating in the wind to achieve more time in the air and hence a longer horizontal distance from the tree. A spinning stone skips over the surface of water.

Similar movements can be seen every day in our society. A cylinder spins about its axis in a fluid flow and experiences an aerodynamic force perpendicular to both the flow and the axis; that mechanism has actually been used to propel ships. A baseball spinning to create a similar aerodynamic force results in a curved pitch. The same thing happens when a golfer hooks or slices a golf shot. Some gun barrels are rifled, or grooved, to impart spin to the bullets. A Frisbee is a spinning disk especially designed to achieve long distances through the air. A boomerang spins in such a way that the aerodynamic force on it leads to circular flight that allows it to return to its owner. And artificial satellites, along with everything else in space—stars, planets, comets, asteroids, and so forth—spin in space.

All examples given here are covered in Ralph D. Lorenz’s Spinning Flight: Dynamics of Frisbees, Boomerangs, Samaras, and Skipping Stones. To my knowledge, Lorenz’s work is the first in which the dynamics of spinning bodies have been treated under a single cover. Some of Lorenz’s examples are esoteric, but all, unified by aspects of spin, have been cleverly put together in a very readable book. The author emphasizes the physical aspects of each situation, with only a minimum of mathematics and formulas. That characteristic is the value of the book, which is not a contribution to the scholarly state of the art but rather a smooth survey of the dynamics of spinning bodies taken as a whole. In that regard, it appears to be complete. Topics in its 14 chapters cover the map, and include the aerodynamics of balls, airbags, tumbleweeds, spinning aircraft, Frisbees, and samara seeds.

Spinning Flight reflects the author’s research. Lorenz, who now works at the Johns Hopkins University Applied Physics Laboratory in Maryland, holds a degree in aerospace engineering. His former position was with the lunar and planetary laboratory at the University of Arizona in Tucson, where he worked on the Huygens probe that descended through the atmosphere of Saturn’s moon Titan in 2005. The author was partially inspired by the phenomenon of spinning objects after observing Huygens spinning under its parachute. As an aerospace engineer who has worked in aerodynamics for almost 50 years, I feel a certain comradeship with the author.

Lorenz’s book is written for the general reader who has a basic science education and is eager to learn about physics, even the most esoteric of subjects. Spinning Flight is the result of the author’s own curiosity about the topic, and he assumes that other people would be curious, too. I believe he assumes correctly. When you want some time off from the intense working environment of the modern technical world, sit down and read Spinning Flight—and enjoy the ride.