How do jumbo jets stay up

The arid climate of these states slows down rusting. These boneyards are open-air storage sites for all sorts of aircraft, from retired commercial carriers to nuclear-capable B bombers.

A total of 4, jets are parked here. Each plane has more than , individual components, such as an engine, munitions, wiring, and electronics. Many of them can be harvested for parts in other aircrafts.

Technicians drain fuel tanks and flush them with lubricant. They cover tires in Mylar to prevent the sun from deteriorating the rubber. They remove explosive devices, such as guns and ejection seat activators. Finally, they paint the top coat in white to deflect the scorching desert sunrays. At AMARG, aircraft are kept at various levels of restoration by a staff of including engineers and inspectors, almost all whom are civilian personnel.

The technicians pay special attention to the retired B bombers, which are capable of carrying thermonuclear weapons. To comply with treaties forged between the U. Permanently retired aircrafts are slowly dismantled over time. The pace of their decommissioning fluctuates with the demand for working spare parts. When parts are cheap, harvesting slows. AMARG has a smelter onsite, where some of the surplus aircraft and their shells are shredded and recycled.

The decommissioning process is largely the same for commercial jets. There are an estimated , aircraft in service today in the United States. Each year, hundreds of them are decommissioned. There are many reasons for taking planes out of service.

United Airlines, for example, is currently considering parking its Boeing fleet as early as to make way for newer, more fuel-efficient planes. Airlines are selling them off, and replacing them with long-range twin-engine aircrafts to save on fuel and maintenance costs. But neither produces a complete explanation of lift, one that provides a full accounting of all the basic forces, factors and physical conditions governing aerodynamic lift, with no issues left dangling, unexplained or unknown.

Does such a theory even exist? Bernoulli came from a family of mathematicians. In other words, the theorem does not say how the higher velocity above the wing came about to begin with.

There are plenty of bad explanations for the higher velocity. Because the top parcel travels farther than the lower parcel in a given amount of time, it must go faster. The fallacy here is that there is no physical reason that the two parcels must reach the trailing edge simultaneously. And indeed, they do not: the empirical fact is that the air atop moves much faster than the equal transit time theory could account for. It involves holding a sheet of paper horizontally at your mouth and blowing across the curved top of it.

The page rises, supposedly illustrating the Bernoulli effect. The opposite result ought to occur when you blow across the bottom of the sheet: the velocity of the moving air below it should pull the page downward.

Instead, paradoxically, the page rises. On a highway, when two or more lanes of traffic merge into one, the cars involved do not go faster; there is instead a mass slowdown and possibly even a traffic jam. That lower pressure, added to the force of gravity, should have the overall effect of pulling the plane downward rather than holding it up. Moreover, aircraft with symmetrical airfoils, with equal curvature on the top and bottom—or even with flat top and bottom surfaces—are also capable of flying inverted, so long as the airfoil meets the oncoming wind at an appropriate angle of attack.

The theory states that a wing keeps an airplane up by pushing the air down. The Newtonian account applies to wings of any shape, curved or flat, symmetrical or not. It holds for aircraft flying inverted or right-side up. The forces at work are also familiar from ordinary experience—for example, when you stick your hand out of a moving car and tilt it upward, the air is deflected downward, and your hand rises. But taken by itself, the principle of action and reaction also fails to explain the lower pressure atop the wing, which exists in that region irrespective of whether the airfoil is cambered.

It is only when an airplane lands and comes to a halt that the region of lower pressure atop the wing disappears, returns to ambient pressure, and becomes the same at both top and bottom. But as long as a plane is flying, that region of lower pressure is an inescapable element of aerodynamic lift, and it must be explained. Neither Bernoulli nor Newton was consciously trying to explain what holds aircraft up, of course, because they lived long before the actual development of mechanical flight.

Their respective laws and theories were merely repurposed once the Wright brothers flew, making it a serious and pressing business for scientists to understand aerodynamic lift. Most of these theoretical accounts came from Europe. In the early years of the 20th century, several British scientists advanced technical, mathematical accounts of lift that treated air as a perfect fluid, meaning that it was incompressible and had zero viscosity. These were unrealistic assumptions but perhaps understandable ones for scientists faced with the new phenomenon of controlled, powered mechanical flight.

These assumptions also made the underlying mathematics simpler and more straightforward than they otherwise would have been, but that simplicity came at a price: however successful the accounts of airfoils moving in ideal gases might be mathematically, they remained defective empirically.

In Germany, one of the scientists who applied themselves to the problem of lift was none other than Albert Einstein. Einstein then proceeded to give an explanation that assumed an incompressible, frictionless fluid—that is, an ideal fluid. To take advantage of these pressure differences, Einstein proposed an airfoil with a bulge on top such that the shape would increase airflow velocity above the bulge and thus decrease pressure there as well.

Einstein probably thought that his ideal-fluid analysis would apply equally well to real-world fluid flows. He brought the design to aircraft manufacturer LVG Luftverkehrsgesellschaft in Berlin, which built a new flying machine around it.

Contemporary scientific approaches to aircraft design are the province of computational fluid dynamics CFD simulations and the so-called Navier-Stokes equations, which take full account of the actual viscosity of real air. Still, they do not by themselves give a physical, qualitative explanation of lift. In recent years, however, leading aerodynamicist Doug McLean has attempted to go beyond sheer mathematical formalism and come to grips with the physical cause-and-effect relations that account for lift in all of its real-life manifestations.

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 text Understanding Aerodynamics: Arguing from the Real Physics.

Considering that the book runs to more than pages of fairly dense technical analysis, it is surprising to see that it includes a section 7. Download it here.

By Rick Adams El Segundo. Jumbo jets Have you ever wondered how those things stay in the sky? Why Is the Sky Blue? But how do they get up there? OK, just the birds, their wings to be specific.