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Topic: Coefficient of lift


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In the News (Wed 11 Nov 09)

  
  Lift coefficient - Wikipedia, the free encyclopedia
Note that the lift equation does not include terms for angle of attack — that is all wrapped up within the description of airfoil geometry, and the coefficient of lift incorporates this term.
This is known as the stall angle of the airfoil.
The coefficient of lift is a dimensionless number.
en.wikipedia.org /wiki/Coefficient_of_lift   (316 words)

  
 Lift (force) - Wikipedia, the free encyclopedia
Lift consists of the sum of all the fluid dynamic forces on a body perpendicular to the direction of the external flow approaching that body.
Since it is a two-dimensional vector equation, and since lift is perpendicular to drag, this equation suffices to predict both lift and drag.
A third way to calculate lift is to determine the mathematical quantity called circulation; (this concept is sometimes applied approximately to wings of large aspect ratio as "lifting-line theory").
en.wikipedia.org /wiki/Lift_(force)   (2033 words)

  
 The Lift Coefficient
The lift coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and some flow conditions on lift.
This equation is simply a rearrangement of the lift equation where we solve for the lift coefficient in terms of the other variables.
The lift coefficient then expresses the ratio of the lift force to the force produced by the dynamic pressure times the area.
www.grc.nasa.gov /WWW/K-12/airplane/liftco.html   (440 words)

  
 Modern Lift Equation
The modern lift equation states that lift is equal to the lift coefficient (Cl) times the density of the air (r) times half of the square of the velocity (V) times the wing area (A).
The lift coefficient of the modern equation is referenced to the dynamic pressure of the flow, while the lift coefficient of the earlier times was referenced to the drag of an equivalent flat plate.
The lift to drag ratio is an efficiency factor for the aircraft and directly related to the glide angle.
wright.nasa.gov /airplane/lifteq.html   (1126 words)

  
 Lift, Thrust, Weight, and Drag [Ch. 4 of See How It Flies]
Lift is the component of aerodynamic force perpendicular to the relative wind.
the coefficient of lift is proportional to the angle of attack,
the coefficient of induced drag is proportional to the square of the angle of attack, and
www.av8n.com /how/htm/4forces.html   (2984 words)

  
 Lift Equation of the 1900's
The amount of lift generated by an object depends on a number of factors, including properties of the air, the velocity between the object and the air, the surface area over which the air flows, the shape of the body, and the body's inclination to the flow, also called the angle of attack.
Modern lift coefficients relate the lift force on the object to the force generated by the dynamic pressure times the area, while the 1900's lift coefficients relate the lift force to the drag of a flat plate of equal area.
The brothers tested over fifty different models to determine how lift and drag are affected by various design parameters and they used this data to design their 1902 aircraft using the lift equation shown on the slide with their own lift coefficients.
wright.nasa.gov /airplane/liftold.html   (779 words)

  
 The Lift Equation
Lift depends on the density of the air, the square of the velocity, the air's viscosity and compressibility, the surface area over which the air flows, the shape of the body, and the body's inclination to the flow.
For lift, this variable is called the lift coefficient, designated "Cl." This allows us to collect all the effects, simple and complex, into a single equation.
The lift equation states that lift L is equal to the lift coefficient Cl times the density r times half of the velocity V squared times the wing area A.
exploration.grc.nasa.gov /education/rocket/lifteq.html   (269 words)

  
 How Lift is Created
Lift is a force on a wing (or any other solid object) immersed in a moving fluid, and it acts perpendicular to the flow of the fluid.
The lift coefficient of an airfoil is a number that relates its lift-producing capability to air speed, air density, wing area and angle of attack -- the angle at which the airfoil is oriented with respect to the oncoming air flow (we'll discuss this in greater detail later in the article).
The lift coefficient of a given airfoil depends upon the angle of attack.
library.thinkquest.org /C0111604/how_lift_is_created.htm   (729 words)

  
 Lift and Drift
The lower the lift or the higher the drag, the greater the angle of the rope as measured from the vertical.
The coefficients of lift and drag apparently changed not only with the angle of attack at which the wind met the wing, but also the shape of the wing -- the camber, the curvature, and the aspect ratio.
The lift balance, for example, pitted the force of lift generated by an airfoil against the pressure on a plate the same size as the airfoil.
www.first-to-fly.com /Adventure/Workshop/lift_and_drift.htm   (6216 words)

  
 Vertical Damping, Roll Damping, and Stalls [Ch. 5 of See How It Flies]
As discussed in section 2.12, there is a deep relationship between airspeed and coefficient of lift; if the coefficient of lift is small the airplane has to fly at a higher speed to support its weight.
In some aircraft, the stall occurs quite suddenly, because there is a rather sharp corner in the coefficient of lift curve, as shown in figure 5.6.
For the coefficient of lift curve shown in figure 5.5, the vertical damping goes away gradually as you approach the stall.
www.av8n.com /how/htm/vdamp.html   (4443 words)

  
 Aerodynamics for Students
The span-wise lift distribution is assumed to be elliptical with a small modification due to wing planform geometry.
The lift coefficient for the wing at a given angle of attack will be obtained by integrating the spanwise vortex distribution.
By integrating the component of section lift coefficient that acts parallel to the freestream across the span, the induced drag coefficient can be found.
www.ae.su.oz.au /aero/liftline/liftline.html   (811 words)

  
 Lift and Drag Curves- level 3
The lift-drag ratio is used to express the relation between lift and drag and is obtained by dividing the lift coefficient by the drag coefficient, C
We find that the coefficients of lift, drag and moment depend upon the angle of attack, the mach number and the Reynolds number.
For subsonic speeds, normal airfoils have a linear relationship between angle of attack and coefficient of lift until just before stall occurs (the airfoil or wing experiences a loss of lift).
www.allstar.fiu.edu /aero/lift_drag.htm   (853 words)

  
 Embry-Riddle - High Lift Devices
By increasing the camber of an airfoil, the coefficient of lift for a given angle of attack is increased.
As flaps are extended, the coefficient of lift is increased for a given angle of attack, but the coefficient of drag increases faster than the coefficient of lift, resulting in a lower L/D ratio.
The drag polar plots the coefficient of lift versus the coefficient of drag.
www.erau.edu /er/newsmedia/articles/wp1.html   (1527 words)

  
 Basic Aerodynamics - Chapter 2
The lift an airfoil generates is a reflection of the fact that the static pressure on the top surface of the wing is lower than that on the bottom surface.
Since pressure is a force per unit area, the total lift is directly proportional to the wing area and is directly proportional to the air density.
These Coefficient of Lift curves are shown for both a subsonic asymmetric airfoil and a swept wing symmetrical airfoil.
www.petester.com /html/bachap02.html   (1168 words)

  
 Prepare for Lift-Off
Typical accidents that are often the result of a lack of understanding of lift and sections is the failure of a model to recover from a high speed dive or a model falling out of the sky in light lift conditions.
Lift, in simple terms is the force created by the pressure difference of the air between the top and bottom of a flying surface i.e.
Not all lift is produced by the top surface of the wing, some is produced by the lower surface as a result of an increase in pressure under the wing.
www.phoenixmp.com /articles/prepforliftoff.htm   (2321 words)

  
 Sail section lift
In theory, the lift coefficient at zero angle of attack is 4 pi times the camber for a circular arc plate -- about 1.26 for our 10% cambered plate.
Turns out that these two coefficients are the same, and the additional lift of a cambered plate over a flat plate is pretty much a constant, due to its camber.
The zero lift angle of attack is theoretically important because it is the point at which the cambered plate begins to develop lift.
www.onemetre.net /Design/SailSect/SailSect.htm   (856 words)

  
 :: NASA Quest > Aerospace ::   (Site not responding. Last check: 2007-10-01)
Lift is the name given to the force that enables an airplane to rise off of the ground.
Theoretically, the amount of lift obtained from a wing should be proportional to the pressure and the wing area.
Coefficient of lift increases as the angle of attack increases.
quest.arc.nasa.gov /aero/wright/teachers/up.html   (2898 words)

  
 Atkinsopht/Rowing/Oarblade Lift and Drag   (Site not responding. Last check: 2007-10-01)
Also plotted here is the lift coefficient of a hypothetical blade with the zero attack angle characteristic of an airfoil (the stall points for most airfoils are around fifteen degrees).
Unfortunately, where it is most wanted, lift has a limited effect owing first to the fact that the shell-longitudinal components of the forces are small at small oarshaft bow angles and second to the fact that the rower's effort at the beginning and end of the stroke is small.
In fact, the zero lift attack angle may be simply added to the blade cant angle and the resulting tractrix calculated directly for comparison with the actual blade center locus as modified by slip.
www.atkinsopht.com /row/liftdrag.htm   (2504 words)

  
 Aerospaceweb.org | Ask Us - Lift Coefficient & Thin Airfoil Theory
Background information on the lift coefficient and how it is used to calculate the lift force acting on a vehicle is available in previous questions.
The only problem with the equation is that all of the complex aerodynamics that go into generating lift are hidden away in the somewhat vague lift coefficient variable.
This graph compares the lift coefficient vs. angle of attack for two actual aircraft, as measured in wind tunnel experiments, compared to the ideal lift coefficient predicted by the Thin Airfoil Theory equation you ask about.
www.aerospaceweb.org /question/aerodynamics/q0136.shtml   (904 words)

  
 Assignment 1- Analysis of the Wright flyer
Using the lift line program downloaded from the University of Sydney website we were able to use Prandtl’s theorem to calculate the coefficient of lift and the coefficient of induced drag at various angles of attack.
At and angle of attack of 15 degrees the coefficient of lift is.93.
This also means that the lift to drag ratio will equal the ration of the coefficient of lift to coefficient of drag ratio.
www.prism.gatech.edu /~gtg680f/paper.html   (1837 words)

  
 Nasaexplores
Students will analyze a graph plotting angle of attack versus coefficient of lift (CL) and graph of angle of attack versus CL for the data collected in the Wright Flyer wind tunnel data collected at Ames Research Center.
Coefficient of lift is how efficiently the wing is transforming dynamic pressure into lift.
The advantage of the lift curve is that it tells the CL and therefore lift available for a certain angle of attack.
www.nasaexplores.com /show_912_teacher_st.php?id=030107165607   (1103 words)

  
 Program Files\Netscape\Communicator\Program\BOBSPAGE\calcman1
For a symmetrical airfoil the maximum coefficient of lift is approximately 0.8 at a 10 degree angle of attack.
Locate the coefficient of lift mark of 0.8, the stalling speed at sea level is aligned with this mark, Ex.
The coefficient of lift is a function of the airfoil shape and its angle of attack.
pages.sbcglobal.net /limeybob/calcman1.html   (2076 words)

  
 Pilot's Web The Aviators' Journal - More About Lift and Drag
The air velocity is a major contributor to lift and drag because both are proportional to square of the velocity.
From the lift and drag formulas, it follows that the velocity and the angle of attack (represented by either CL or CD) are inversely proportional.
The aerodynamic efficiency is defined as the ratio between the lift coefficient and the drag coefficient.
www.pilotsweb.com /principle/liftdrag.htm   (1511 words)

  
 Embry-Riddle - When Lift Fails
Another disadvantage of the swept wing is that as the stall progresses the area producing lift shrinks forward and the center of lift load has a pronounced forward shift.
The extension of flaps also increases the maximum coefficient of lift by increasing the wing camber (curvature), and, with some flaps, the boundary layer energy.
As the lift vector is deflected, less of it remains in the vertical direction.
www.erau.edu /er/newsmedia/articles/wp3.html   (2672 words)

  
 First Flight
They had based their designs on the tables for the coefficient of lift published by the pioneering German aviatior Lilienthal, but they now realised that these were wrong because Lilienthal had assumed a value for Smeaton's coefficient that was too high.
Now that they could measure the lift coefficient, the Wrights designed the drift balance to directly measure the drag to lift ratio.
The Wright Brothers were able to develop a much better understanding of how the shape of a wing determined its aerodynamic properties than anyone before them, and this led to the improved performance of their planes after 1902.
firstflight.open.ac.uk /experiments01.html   (197 words)

  
 Lift in Level Flight   (Site not responding. Last check: 2007-10-01)
Since we need a specific amount of lift in order to maintain straight and level flight, turn, climb or descend, we must be able to control the amount of lift produced.
We can control Coefficient of lift only by changing the shape of the airfoil (as in extending or retracting flaps) or by changing the angle of attack, using the elevators.
Generally you can assume that the same lift is required in a climb or a descent as in Straight and Level Flight.
selair.selkirk.bc.ca /aerodynamics1/Lift/Page7.html   (901 words)

  
 Thesis - Drag
It has seven inputs, which are control input, wind axes velocity, altitude, wing’s coefficient of lift, horizontal tail’s coefficient of lift, dynamic pressure and the angular rates.
It starts with obtaining the profile coefficient of drag of the wing, which is a function of flaps deflection angle and the angle of attack.
At the same time, the wing-induced coefficient of drag is calculated from the coefficient of lift of the wing.
students.db.erau.edu /~mohdanwm/Thesis/Drag.htm   (361 words)

  
 Aviation Today - Top Story
Indeed, a plot of coefficient of lift against increasing angle-of-attack follows a rising line that starts to flatten out near the top.
The apex of this curve is the "critical angle-of-attack," or the point at which maximum lift is being generated.
There is a range of angles-of-attack near the top of the flattening curve that produce about the same high coefficient of lift, but the lift corresponds to a very narrow range of airspeeds—which happen to cluster near the stall speed.
www.aviationtoday.com /sia/19991001.htm   (1196 words)

  
 lift forces
Every time you fly in an airplane, you rely on the force of lift to hold your vehicle aloft.
Lift is due to a difference in pressure between the top and bottom of an object in flow.
Among other things, this equation indicates that higher velocities produce greater lift forces.
www.mbari.org /staff/conn/botany/methods/methods/lift.htm   (143 words)

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