Here are a few words from the author, a wind energy professional in Tehachapi, California, about the booklet:

"What should be understood first and foremost is that air has mass and weight. Under standard conditions it has a weight of just about 2 pounds per cubic yard (1.2 kilograms per cubic meter). Think of rocks that weigh that much or a quart of water. The wing of an aircraft in flight or the blades of a wind turbine must redirect this substance, which becomes "weighty" in large volumes, to provide the forces necessary to achieve their purposes.

"Past doctrine has been to provide a few insights about what happens to the airflow immediately adjacent to the airfoil surfaces as if that is all that mattered. In this context such questions as whether the flow next to these surfaces is accelerated or not in going over them, how detailed pressure patterns are generated on them, and whether the flow over the top of the body meets up in exactly the same place with the flow below it at the trailing edge can be debated at length with little or no resolution. The amount of flow nearby in terms of the mass quantities involved can not be significant in any event. These discussions miss the big picture. It is what happens to the great volumes of air with their corresponding masses passing by up to large distances away from the deflecting surfaces that matters to the exclusion of all else.

"In drawing the vector diagrams for the mass flow deflection processes involved it is quickly realized that the airflow across the wing of an airplane is directed downwards but not straight downwards. The vectors show that it must always have a small forward component as well. This forward component is the source of the induced drag that always accompanies lift and both vary as angular functions with the angle of attack. In producing lift, an angle of attack is necessary but not to the extent of producing excessive drag. In aircraft, then, the angles of attack of wings are generally maintained at low values for this reason. For wind turbine blades it is the opposite. Energy must be converted as efficiently as possible and so the angles of airflow deflection tend to be greater.

"This approach satisfies the basic laws of mass and momentum conservation in a satisfactory way. By now, books are being published that provide better insights and good generalized descriptions of the new, updated thinking.

"These basic concepts in wind energy at the detail of what happens to wind turbine blades all along their lengths form excellent studies for all those who have an interest in its development."

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Integrated Energies - Wind
21331C Golden Hills Blvd.
Tehachapi, California 93561