Since the beginning of recorded history, humans have always had a fascination with flight. Now that we live in a world where boarding an airplane and flying across the country – or even the world - is simply a part of everyday life, the wonder of flight has diminished for many. Despite this, physics students from all around continue to delight in the many physical forces that play a part in keeping these huge objects (like jumbo jets) from falling out of the sky!
The common explanation given to those curious about how an airplane wing produces lift uses the Bernoulli Principle. This is the concept that because of the airfoil shape of a wing, the air traveling over the top of the wing must travel faster than the air going under the wing because it has to travel a farther distance. The resulting difference in pressure between the two (higher pressure under the wing) creates lift, keeping the plane in the air.
This explanation is unsatisfactory in a number of ways. It does not consider or explain the important role that the angle of attack plays in flight, nor does not explain how planes can fly upside down (where according to the Bernoulli Principle, the pressure would actually be higher on the top of the wing, pushing the plane down to the ground!). For some interesting arguments and calculations refuting the Bernoulli Principle as a sound explanation for lift in an airplane, check out Gail Craig’s book “Stop Abusing Bernoulli! How Airplanes Really Fly” available from Regenerative Press (see bibliography).
Although the Bernoulli Principle is used to describe many physical phenomena, it does not explain lift. Luckily for us there is a much more sound explanation for how an airplane flies! There are four main forc...
... middle of paper ...
...er angle of attack helps divert more air downwards, thus creating more lift. If one imagines the air particles as bullets hitting the wing of the airplane, an increased angle of attack increases the number of air particles that will hit the bottom of the wing, thus increasing the amount of air being “scooped” and diverted downwards.
However, there is a limit to this great thing we call angle of attack. Generally any angle greater than 15 degrees will cause the plane to stall. The stall happens because, as discussed earlier, the viscous property of air “wants” to follow a curve, but is limited to its level of “stickiness” to the surface of the plane. As the angle of attack increases, the air has a harder time “sticking” to the surface and eventually simply passes right over the wing without following the surface, resulting in the loss of lift (a.k.a. stall).
Boeing Ltd. has initiated a project that will improve the design aircraft. This design will provide a safer and more comfortable flight. In conjunction with this project, Batchel...
Aerodynamics is generally summarized in these 2 terms: “Lift against Weight” and “Thrust against Drag”. This basically means the amount of flight power generated must be equal to, or greater than the amount of weight of the airplane, and the amount of pushing generated, must be equal to or greater than the airs resistance. But the overall question, so far, is how is “Lift” and “Thrust” generated? The answer to how “Thrust” is generated is quite simple. Its sort of how a car would move, except in a much different way. Airplanes have 4 engines, which can each exert easily up to 200 PSI of air (pressure per square inch), composed of liquid fuel cylinders, and internal combustion (like a car). It also tops to 250 km per hour on the runway! But how “Lift” is generated is, the true definition of aerodynamics. The first thing you must consider to understand this is that the wing of the plane is specially designed, to force the air above the wing to rush faster, than the air beneath it. This works according to the “Bernoulli’s principle”. The reason air above the wing must be fast...
The wing keeps the airplane up by pushing the air down. A similar statement can be made for propellers and hexacopters. If the thrust of the air pushed downward by the propellers exceeds the body’s weight, the hexacopter rises. Air that isn’t affected by a propeller is said to be in the free stream state. In this case, the air simply drifts from place to place, and this velocity is denoted by v_0 .
As it has been named, "Bernoulli’s" argument states that the reason lift is created in wings is that the upper surface of the wing is curved, and therefore longer than the underside of the wing (In truth, Bernoulli had nothing to do with this explanation of lift, it is only attributed to his principle). The argument goes on to say that if the upper surface is longer than that of the bottom, the air flowing over the upper surface must travel faster as it has farther to travel. Using Bernoulli’s Principle this explanation says that because the air traveling over the top of the wing is moving faster than the air under the wing the air above the wing exerts less pressure on the wing than the air under the wing. If there is less pressure above the wing then the air under the wing will push upwards on the...
First of all you will have to understand the principles of flight. An airplane flies because air moving over and under its surfaces, particularly its wings, travels at different velocities, producing a difference in air pressure, low above the wing and high below it. The low pressure exerts a pulling influence, and the high pressure a pushing influence. The lifting force, usually called lift, depends on the shape, area, and tilt of the wing, and on the speed of the aircraft. The shape of the wing causes the air streaming above and below the wing to travel at different velocities. The greater distance over which the air must travel above the curved upper surface forces that air to move faster to keep pace with the air moving along the flat lower surface. According to Bernoulli’s principle, it is this difference in air velocity that produces the difference in air pressure.
For a plane to create lift, its wings must create low pressure on top and high pressure on the bottom. However, at the tips of the wings, the high pressure pushes and the low pressure pulls air onto the top of the wing, reducing lift and creating a current flowing to the top. This current remains even after the wing has left the area, producing really awesome vortices.
Heppenheimer, T. (2001). A Brief History Of Flight: From Balloons to Mach 3 and Beyond. Canada: John Wiley & Sons, Inc.
All flight is the result of forces acting upon the wings of an airplane that allow it to counteract gravity. Contrary to popular belief, the Bernoulli principle is not responsible for most of the lift generated by an airplanes wings. Rather, the lift is created by air being deflected off the wings and transferring an upward force to those wings.
This paper will explain a few of the key concepts behind the physics of skydiving. First we will explore why a skydiver accelerates after he leaps out of the plane before his jump, second we will try and explain the drag forces effecting the skydiver, and lastly we will attempt to explain how terminal velocity works.
plane and a boat's sail lifts and pushes it forward. Imagine the sail of a boat
Wings create lift for the upward force of an airplane. A great example of how this happens is sticking your hand out of a car window driving down the freeway. The force on your flat palm causes a force that can lift your hand up or down by changing the
Ever since I was little I was amazed at the ability for a machine to fly. I have always wanted to explore ideas of flight and be able to actually fly. I think I may have found my childhood fantasy in the world of aeronautical engineering. The object of my paper is to give me more insight on my future career as an aeronautical engineer. This paper was also to give me ideas of the physics of flight and be to apply those physics of flight to compete in a high school competition.
The basic concepts of lift for an airplane is seen. The air that is flowing splits to move around a wing. The air that that moves over the wing speeds up creating lower pressure which means that the higher pressure from the air moving slower under the wing pushes up trying to equalize the pressure. The lift generated can be affected by the angle at which the wing is moving into the flowing air. The more surface area of the wing resisting against the flow of air can either generate lift or make the plane dive. This can be easily simulated in everday life. Next time you are riding in a car with someone stick your hand out the window. Have your fingers pointing in the direction of the motion of the vehicle. Now move your hand up and down slightly. You can feel the lift and drag that your hand creates.
Lift is generated by the air flow around the plane's wing. This effect is explained mostly by Bernoulli's Principle which states that the pressure of the air decreases as the velocity of the air increases. The design of a plane's wing changes the airflow around the wing's surface. The air has farther to travel over the top of the wing than the air traveling below the wing. Therefore, the air traveling above the wing is traveling at a higher velocity than the air traveling below it. As air flows around the wing, a high pressure region with low air velocity is created below the wing, and a low pressure region with high air velocity is created above the wing. The difference between the two pressures generates the lift force. (JEPPESEN 1-11)
Subsequently, this kind of the long-distance effect had to occur more and more away from the position of launching to prevent self-damage. Therefore, the fulfillment of a long dream of the human race, to be able to fly, came just in time – and now, not everything that came from above was good anymore.