I prefer air signs more than the others. Browse the resources on the next page to learn more about renewable energy. Because of this, the SWP is California’s largest energy consumer, and even though the hydroelectric plants of the SWP generate 5,900 GWh per year, that is only a fraction of the energy needed to lift water over the Tehachapis. Water-channel test at NASA Ames Fluid Mechanics Labuses fluorescent dye to visualize the flow field over an airplane wing. McLean’s complex explanation of lift starts with the basic assumption of all ordinary aerodynamics: the air around a wing acts as “a continuous material that deforms to follow the contours of the airfoil.” That deformation exists in the form of a deep swath of fluid flow both above and below the wing. It is as if those four components collectively bring themselves into existence, and sustain themselves, by simultaneous acts of mutual creation and causation. Cambridge aerodynamicist Babinsky says, “I hate to disagree with my esteemed colleague Mark Drela, but if the creation of a vacuum were the explanation, then it is hard to explain why sometimes the flow does nonetheless separate from the surface.

Typically, a diesel engine drives the air compressor, which then forces the air through a hose to the end tool — in this case a jackhammer. Then apply a second coat of mascara. McLean’s answer: Newton’s second law of motion. But if neither Bernoulli’s principle nor Newton’s third law explains it, what does? Newton’s second law states that the acceleration of a body, or a parcel of fluid, is proportional to the force exerted on it. “Newton’s second law tells us that when a pressure difference imposes a net force on a fluid parcel, it must cause a change in the speed or direction (or both) of the parcel’s motion,” McLean explains. But reciprocally, the pressure difference depends on and exists because of the parcel’s acceleration. In a previous unit, it was stated that all objects (regardless of their mass) free fall with the same acceleration – 9.8 m/s/s. But why do all objects free fall at the same rate of acceleration regardless of their mass?

This particular acceleration value is so important in physics that it has its own peculiar name – the acceleration of gravity – and its own peculiar symbol – g. Understanding Aerodynamics: Arguing from the Real Physics. McLean, who spent most of his professional career as an engineer at Boeing Commercial Airplanes, where he specialized in CFD code development, published his new ideas in the 2012 text Understanding Aerodynamics: Arguing from the Real Physics. Considering that the book runs to more than 500 pages of fairly dense technical analysis, it is surprising to see that it includes a section (7.3.3) entitled “A Basic Explanation of Lift on an Airfoil, Accessible to a Nontechnical Audience.” Producing these 16 pages was not easy for McLean, a master of the subject; indeed, it was “probably the hardest part of the book to write,” the author says. Nevertheless, there are at this point only a few outstanding matters that require explanation. Between 1978 and 1988, there were roughly 26 incidents of hijackings a year. “One apparent problem is that there is no explanation that will be universally accepted,” he says. Although the article largely restates McLean’s earlier line of argument, it also attempts to add a better explanation of what causes the pressure field to be nonuniform and to assume the physical shape that it does.

In particular, his new argument introduces a mutual interaction at the flow field level so that the nonuniform pressure field is a result of an applied force, the downward force exerted on the air by the airfoil. “The airfoil affects the pressure over a wide area in what is called a pressure field,” McLean writes. “The reduced pressure over a lifting wing also ‘pulls horizontally’ on air parcels as they approach from upstream, so they have a higher speed by the time they arrive above the wing,” Drela says. “The pressure differences exert the lift force on the airfoil, while the downward turning of the flow and the changes in flow speed sustain the pressure differences.” It is this interrelation that constitutes a fifth element of McLean’s explanation: the reciprocity among the other four. This means that there are four necessary components in McLean’s explanation of lift: a downward turning of the airflow, an increase in the airflow’s speed, an area of low pressure and an area of high pressure. In addition, there is an area of high pressure below the wing and a region of low pressure above.