How do aerodynamics work on airplanes

An understanding of flight is rooted in a strong grasp of how an airplane gets in the air—and stays there. Both a passenger jet and a tiny paper airplane are governed by the same forces. Understanding airplane aerodynamics is key to a successful partnership with the atmosphere: They are the foundation for study for student pilots , an instinctive part of work life for engineers and everyday aviators, and a pathway to comprehension and relaxation for white-knuckle travelers.

You may be surprised to hear that aerodynamics applies to objects that never leave a runway at all. Where those in the aviation industry are concerned, however, aerodynamics applies to how the forces of flight act on an aircraft. We need help! When the Wright Brothers were designing their first Flyer , they took careful note of how the birds along the North Carolina coast wheeled and glided on the ocean wind.

They understood that, unlike people, birds were built to manage four important forces: weight, lift, thrust, and drag. These four staples of aerodynamics are constantly working in opposition to one another. It has a specific relationship to airplanes and management of them while in flight. Aircraft designers usually look to save as much weight as possible ; a lower weight means less fuel to remain airborne, and more passengers and cargo can be brought on board.

Seeking a balance of using safe and durable materials while reducing the forces of gravity is critical. The center of gravity is always focused towards the earth, but the precise location of it continually shifts as an airplane burns fuel.

Weight and balance calculations are vital in-flight planning and aircraft operation. Maintaining a safe ratio of weight and balance are why, even though passengers on a small aircraft might not feel a difference in the handling of an aircraft, they are sometimes asked to re-distribute themselves more evenly across the cabin of a half-empty flight.

So what combats the weight of the aircraft pushing down towards Earth? In aerodynamics, lift is produced by the difference in speed between an object and the air molecules around it. Lift does not exist without air, which is why the wings of the space shuttle orbiter were useless in the vacuum of space but essential during its unpowered descent to Earth.

Differences in air pressure are crucial in producing lift. Since fast-moving air creates less pressure, the slower air below the wing helps to push the wing skyward. Aircraft wings, with their slightly rounded shape, are designed to harness this dynamic. The motion of the air molecules above and below the surface of the wing creates the upward push of lift; this flow, in turn, helps keep the airplane aloft. The most spectacular illustration of thrust is a rocket launch.

Thrust is what enables us non-birds to get off the ground. Attaining significant amounts of thrust was the most difficult problem of aerodynamics to solve. Lack of thrust is why we were forced to wait until the mechanical age to attain flight. The required thrust is generated by the engine or engines. The Wright Brothers custom-built a simple crankcase made of lightweight aluminum , which was gravity-fed by a tiny gasoline tank. It only produced 12 horsepower as opposed to the , from a single engine on the Boeing Dreamliner , but it was enough to overcome the gravitational pull of the Flyer and one Wright.

Any object such as an airplane moving through molecules such as the atmosphere experiences drag. This friction can be reduced by constructing flight-bound objects with smooth materials. Do you love the sweeping look of winglets on a modern jet? That combats the action of lift. But in a widebody jet, the presence of a well-designed winglet—a wing on top of a wing—helps to push airflow towards the fuselage of the airplane.

Weight, lift, thrust and friction are constantly pushing and pulling on one another, with the airplane in the middle. Applying aerodynamic principles to all aspects of flight is essential to advancing the scope of aviation. Matthew A. Johnston has over 23 years of experience serving various roles in education and is currently serving as the President of California Aeronautical University.

He is proud of his collaboration with airlines, aviation businesses and individual aviation professionals who are working with him to develop California Aeronautical University as a leader in educating aviation professionals. It is with the essence of great levels of a heavenly order of intelligence to observe the great abilities of humans.

Surely, the invention of the airplane was indeed created by superior minded men having the ability of the structure and design related to the science of great systems of aerodynamics. 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.

I was never entirely happy with it. Where these clouds touch the airfoil they constitute the pressure difference that exerts lift on the airfoil. The wing pushes the air down, resulting in a downward turn of the airflow. In addition, there is an area of high pressure below the wing and a region of low pressure above.

It is as if those four components collectively bring themselves into existence, and sustain themselves, by simultaneous acts of mutual creation and causation. There seems to be a hint of magic in this synergy. And what causes this mutual, reciprocal, dynamic interaction? McLean says no: If the wing were at rest, no part of this cluster of mutually reinforcing activity would exist. But the fact that the wing is moving through the air, with each parcel affecting all of the others, brings these co-dependent elements into existence and sustains them throughout the flight.

Soon after the publication of Understanding Aerodynamics , McLean realized that he had not fully accounted for all the elements of aerodynamic lift, because he did not explain convincingly what causes the pressures on the wing to change from ambient. 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.

There are reasons that it is difficult to produce a clear, simple and satisfactory account of aerodynamic lift. Some of the disputes regarding lift involve not the facts themselves but rather how those facts are to be interpreted, which may involve issues that are impossible to decide by experiment.

Nevertheless, there are at this point only a few outstanding matters that require explanation. Lift, as you will recall, is the result of the pressure differences between the top and bottom parts of an airfoil. We already have an acceptable explanation for what happens at the bottom part of an airfoil: the oncoming air pushes on the wing both vertically producing lift and horizontally producing drag. The upward push exists in the form of higher pressure below the wing, and this higher pressure is a result of simple Newtonian action and reaction.

Things are quite different at the top of the wing, however. A region of lower pressure exists there that is also part of the aerodynamic lifting force. We know from streamlines that the air above the wing adheres closely to the downward curvature of the airfoil. This is the physical mechanism which forces the parcels to move along the airfoil shape.

A slight partial vacuum remains to maintain the parcels in a curved path. This drawing away or pulling down of those air parcels from their neighboring parcels above is what creates the area of lower pressure atop the wing. But another effect also accompanies this action: the higher airflow speed atop the wing.

But as always, when it comes to explaining lift on a nontechnical level, another expert will have another answer. But he is correct in everything else. The problem is that there is no quick and easy explanation. Drela himself concedes that his explanation is unsatisfactory in some ways. So where does that leave us? In effect, right where we started: with John D. This article was originally published with the title "The Enigma of Aerodynamic Lift" in Scientific American , 2, February How Do Wings Work?

Holger Babinsky in Physics Education , Vol. David Bloor. University of Chicago Press, Understanding Aerodynamics: Arguing from the Real Physics. Doug McLean. Wiley, You Will Never Understand Lift. Peter Garrison in Flying ; June 4, Culick; July Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue.

See Subscription Options. In Brief On a strictly mathematical level, engineers know how to design planes that will stay aloft.