Here’s a book by Dr. Vaughn Nelson of West Texas A & M University that features Makani and me, among many others:
Innovative Wind Turbines: An Illustrated Guidebook, Nelson, Vaughn, eBook - Amazon.com:
One topic discussed is the basic categories of wind energy devices, such as “Drag Devices”. (you know - the name AWE people erroneously gave to compound-lift devices such as Makani?)
From Dr. Nelson’s book:
"1.1 DRAG DEVICE In a drag device, the wind pushes against the blades or sails (Figure 1.5). Drag devices are inherently limited in efficiency since the speed of the device or blades is less than the wind speed. The wind pushes on the blades of a drag turbine, forcing the rotor to turn on its axis. Maximum theoretical efficiency is 16% and the maximum speed of the drag device or drag rotor is one-third the wind speed. Note that drag devices have large torque and small rpm. Too many inventors think the high torque means high power—a common misconception. High solidity and low rpm are major disadvantages for drag wind turbines. The earliest known windmills are the Persian windmills, and the ones at Nashtifan, Iran (Figure 1.6) are still operating, grinding grain, although future use is uncertain [1,2]. The windmills are made of wood, clay, and straw. The long axis of the building is erected perpendicular to the predominate winds and curved walls
FIGURE 1.5 Drag device. An example is a sailboat moving downwind."
Now, everyone in wind energy knew what a “drag device” was. Well, except the “AWE” people… (Why? because AWE people were not people in wind energy.) The idea that AWE people were so ignorant of even the most basic wind energy terminology, and chose to stay that way, and even still do to this day(!) was one reason they immediately fell into the category of “idiots” in the minds of “real wind people” (one example being Dr. Vaughn Nelson).
Sure, after a century of being already defined, suddenly, a “drag device” is an airplane that “drags” a lift-based wind turbine around in the sky… Uh-huh, sure…
Oh, and a “lift device” is suddenly a machine where the working surfaces are pulled upward… (well, you know, “lifted”…)
Anyway, Vaughn was nice enough to include my work in his book. I don’t remember if he sent me a copy - if so, it must be in a pile around here somewhere… He used a couple of my pictures in the book:
FIGURE 2.22 Selsam Supertwin; 2 kW, two rotors 3.7 m apart, D = 3 m. (Photo courtesy of Doug Selsam.)
FIGURE 2.23 Doug Selsam with his Sky Serpent, 26 rotors, 1.1 kW at 9 m/s, D = 1 m. (Photo courtesy of Doug Selsam.) 