The Soaring Engine V2
By G Dale
THE SOARING ENGINE series explains how the sun, wind and terrain combine to produce rising air for the soaring pilot to exploit. In this volume you will see how the wind flows over and around hills, ridges and mountains, how thermals form and evolve, the patterns that ridge and thermal activity create in the air and how to use the lift produced both in flat terrain and in mountains. Illustrated with clear simple diagrams, this book is a primer for soaring pilots flying anything from a paraglider to high performance sailplanes.
The first volume of the Soaring Engine introduces ridge flying and thermal soaring, outlining simple models of how these forms of lift work and how you might best use them in flat land or mountain flying. This volume leads straight on from where volume one finishes: it describes Convergence and Wave, the other two forms of lift that are commonly used by glider pilots. If you’re an experienced soaring pilot, confident on the ridges and happy whether you are flying in flat terrain or the mountains – then you can dive in here. If you’re less knowledgeable then you should read volume one first.
Both convergence and wave both occur frequently, in most soaring environments. I’ve flown in convergence systems in the heart of Africa, hundreds of miles from the sea, and I’ve climbed in wave in Australia, where the terrain upwind was completely flat for at least a thousand miles. When clearly marked and working well, both wave and convergence systems open up opportunities to fly in straight lines and in constant lift: a recipe for long, fast flights. However both these forms of lift can also be troublesome, especially when they are not marked by clouds. They are much more complex than either straightforward ridge or thermal lift, demanding a deeper understanding of small scale soaring meteorology and an ability to orient oneself in the air, feeling the “signature” of various types of turbulence in different places. Sometimes they can be so weak that they bring no real benefit to the soaring pilot, merely serving to confuse when the anticipated ridge or thermal lift fails to turn up where expected!
To use either wave or convergence systems effectively you need a good understanding of the underlying physical process, visualizing them with simple mental models that can be applied to the current situation. You don’t have to be a meteorologist but you will need a basic idea of how to read a tephigram, an appreciation that air masses can be either stable or unstable, and an understanding of how changing the temperature of a parcel of air will change its density. You’ll also need to know about the dew point of an air mass and how that can be used to predict the formation of cloud. Some of this information is already outlined in volume one and you’ll find more technical explanations in the appendix to this volume.
And a disclaimer: I’m a glider pilot, not a physicist, and my models and descriptions of how the Soaring Engine works are simplified to help you get a grip of the environment whilst you fly. Both wave and convergence systems are probably better described with more complex physics and a good deal of mathematics: you will not find this kind of analysis here. However I hope the simple sketches and quick explanations in this book will enable you to tackle even difficult and subtle soaring environments with success. Good luck!
• A Temperate Sea Breeze
• Carpet Wind Convergences
• Convergence Between Similar Air Masses
• Convergence Soaring: Summary
• An Introduction to Wave Soaring
• How Wave Works
• Climbing Into the Wave
• Get Established in the Wave
• Soaring Cross Country in the Wave
• Patterns in the Sky
• Soaring Cross Country Under the Wave
• Complications and Curiosities
• Soaring and Wave Flying
• Wave Soaring: Summary
About G Dale
G Dale learned to fly at age 20 with the Dorset gliding club, going professional ten years later. He's worked with Lasham, Bristol and Gloucester, the British Gliding Association, Booker gliding club, Lake Keepit and out of Minden until finally discovering the mountains of New Zealand and starting to coach at Omarama. Currently following the endless summer, working in both Northern and Southern Hemispheres, he's also flying, racing and coaching as often as possible in other places: southern France and the Czech republic this season.
Having owned many sailplanes, he's back right where he started, currently campaigning a Streifenader – modified Libelle 201b with the British Team, club class.