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Topic: Drag coefficient

Related Topics

Parasitic drag

Drag equation

Skin friction

Pressure coefficient

Similitude (model)

Honda Insight

Engine displacement

Hybrid electric vehicle

Toyota Prius

Dimensionless number

List of hybrid cars

Dimensional analysis

SUV

Continuously variable transmission

VTEC

	The Drag Coefficient
		The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag.
		This equation is simply a rearrangement of the drag equation where we solve for the drag coefficient in terms of the other variables.
		The drag coefficient then expresses the ratio of the drag force to the force produced by the dynamic pressure times the area.
	www.grc.nasa.gov /WWW/K-12/airplane/dragco.html (869 words)

	Drag coefficient - Wikipedia, the free encyclopedia
		The drag coefficient is a common metric in automotive design, where designers strive to achieve a low coefficient.
		Minimizing drag is done to improve fuel efficiency at highway speeds, where aerodynamic effects represent a substantial fraction of the energy needed to keep the car moving.
		Reducing drag is also a factor in sports car design, where fuel efficiency is less of a factor, but where low drag helps a car achieve a high top speed.
	en.wikipedia.org /wiki/Drag_coefficient (797 words)

	The Drag Equation
		The amount of drag generated by an object depends on a number of factors, including the density of the air, the velocity between the object and the air, the viscosity and compressibility of the air, the size and shape of the body, and the body's inclination to the flow.
		The drag equation states that drag (D)is equal to a drag coefficient (Cd) times the density of the air (r) times half of the square of the velocity (V) times the wing area (A).
		The drag coefficient is composed of two parts; a basic drag coefficient which includes the effects of skin friction and shape (form), and an additional drag coefficient related to the lift of the aircraft.
	wright.nasa.gov /airplane/drageq.html (906 words)

	Aerodynamic Drag at High Speeds (Site not responding. Last check: 2007-10-26)
		The effect of turbulent transition on the flat plate drag coefficient is shown schematically in Fig 2.
		The drag characteristics at low speeds are strongly affected by the laminar separation and by viscous skin friction, according to a physics explained in the low speed chapter.
		Drag reduction at low speeds is a very open problem in aerodynamics, that only recently has become object of analysis, mainly spurred by technological advances in solar powered flight, high altitude flight, unmanned vehicles, model airplains, and more.
	aerodyn.org /Drag/speed-drag.html (1305 words)

	Aerodynamics of Wind Turbines: Drag
		The reason why drag is much more of a problem for a racing bicyclist than for, say, a runner, is that a fast runner will be moving at speed of some 6 m/s (21 km/h, 13 mph), whereas a racing bicyclist is moving at a speed of some 12 m/s (42 km/h, 26 mph).
		A modern car (drag coefficient 0.34) with a 110 kW (150 HP) engine will be using about 4.6 kW (6 HP) of power to overcome air drag and 11 kW (14 HP) for mechanical propulsion (rolling resistance etc.) when it is being driven at a constant 80 km/h (22.2 m/s, 49 mph).
		Both lift and drag increase in proportion to with the density of air.
	www.windpower.org /en/tour/wtrb/drag.htm (1296 words)

	Drag
		Drag is a resistance force generated by a solid object moving through a fluid.
		Because skin friction drag is an interaction between a solid (the airplane surface) and a gas (the air), the magnitude of skin friction drag depends on the properties of both the solid and the gas.
		Generally, interference drag will add to the component drags but in a few cases, for example, adding tip tanks to a wing, total drag will be less than the sum of the two component drags because of the reduction of induced drag.
	www.centennialofflight.gov /essay/Theories_of_Flight/drag/TH4.htm (1272 words)

	Drag of Blunt Bodies and Streamlined Bodies (Site not responding. Last check: 2007-10-26)
		This drag is associated with the formation of a wake, which can be readily seen behind a passing boat, and it is usually less sensitive to Reynolds number than the frictional drag.
		Formally, both types of drag are due to viscosity (if the body was moving through an an inviscid fluid there would be no drag at all), but the distinction is useful because the two types of drag are due to different flow phenomena.
		The variation of the drag coefficient with Reynolds number is shown in figure 2, and the corresponding flow patterns are shown in figure 3.
	www.princeton.edu /~asmits/Bicycle_web/blunt.html (1069 words)

	AeroRocket only source for AeroCFD, Program Description
		Rocket motor jet effects cause the drag and lift coefficients to be increased slightly in the subsonic regime and decreased slightly in the supersonic regime.
		For this comparison the AeroCFD drag coefficient results were determined at 80 km/hr (72.9 ft/sec), 100 km/hr (91.13 ft/sec) and 120 km/hr (109.36 ft/sec) to correlate with the wind tunnel results in the paper.
		However, for this comparison the Demar wind tunnel drag coefficients were derived from the tabulated drag-mass data that correspond to the measured zero-lift drags.
	www.aerorocket.com /aerocfd.html (3725 words)

	Subsonic Airflow Effects – The Two-Dimensional Coefficients
		Coefficient of drag as a function of angle of attack of airfoil section.
		Usually, the minimum drag coefficient occurs at a small positive angle of attack corresponding to a positive lift coefficient and builds only gradually at the lower angles.
		Notice that the coefficients for three-dimensional flow are capitalized whereas the coefficients for two-dimensional flow use lower case letters.
	www.centennialofflight.gov /essay/Theories_of_Flight/Two_dimensional_coef/TH14.htm (1189 words)

	Top Speed: Speedskating Wind Drag Coefficient
		The drag coefficient and Reynolds Numbers formulas on the right side of Figure 1 are from the Team Arian website: [Team Ariane Aerodynamics Formulas] and will be used shortly.
		Note from figure one that the drag coefficient is about constant for the circular and elliptical shapes until we get near the dip where the stick skater appears.
		Drag coefficient as a function of Reynolds number for smooth circular cylinders and smooth spheres.
	home1.gte.net /pjbemail/Dragcoef.html (1381 words)

	Experimental Drag Coefficient on a Cylinder in a Cross
		Experimental Drag Coefficient on a Cylinder in a Cross-Flow
		In this laboratory, the drag coefficient of a horizontally oriented cylinder was measured and analyzed through the use of a rectangular wind tunnel, a pitot tube, a honeycomb flow starightener and a DC fan run at twenty amperes.
		The drag force in this laboratory was measured with the second indirect method in association with the conservation of mass.
	www.geocities.com /rsbriody/mer033 (372 words)

	Drag in Vehicles
		Drag is a major concern with airplanes although much of the drag is created in the process of creating lift.
		Modern automobiles usually have a drag coefficient of between 0.30 to 0.35, SUV's are in the range of 0.35 to 0.45.
		The flat rear end of truck trailer is a source of drag that is tough to correct because it is important to use all available space for cargo.
	www.maxconrad.com /draginvehicles.htm (399 words)

	[No title] (Site not responding. Last check: 2007-10-26)
		Both the drag and lift forces were converted to a non-dimensional coefficient which allows the drag and lift performance between different vehicles and different setups of the same vehicle to be compared directly.
		All the drag forces that were recorded were negative meaning that the force was acting in the direction of the flow or against the intended movement of the car.
		Lift and Drag: When the drag and lift force were plotted against velocity it was clear that as the velocity in the wind tunnel increases these forces on the car increased as well (Appendix A, Figure 1).
	www1.union.edu /~nazarenm/memo2.doc (877 words)

	EGR 182 - Air Drag
		Furthermore the drag depends upon the exact shape of the object, that is the degree towhich the object is "steamlined".
		Note that the drag coefficient is defined in terms of the magnitude of the drag force and the velocity.
		Thus knowledge of the drag coefficient, the fluid density, the projected area, and the object velocity is sufficient to predict the drag force acting on the object.
	www.eng.auburn.edu /department/me/courses/nmadsen/egr182a/drag01.html (3906 words)

	Race Car Design Tips and Information - Aerodynamics
		Drag, in vehicle aerodynamics, is comprised primarily of two forces.
		Flow detachment applies only to the "rear vacuum" portion of the drag equation, and it is really about giving the air molecules time to follow the contours of a car's bodywork, and to fill the hole left by the vehicle, it's tires, it's suspension and protrusions (ie.
		Drag coefficient, by itself is only useful in determining how "Slippery" a vehicle is. To understand the full picture, we need to take into account the frontal area of the vehicle.
	www.gmecca.com /byorc/dtipsaerodynamics.html (2766 words)

	Pilot's Web The Aviators' Journal - More About Lift and Drag (Site not responding. Last check: 2007-10-26)
		To minimize the parasite drag it is desired to design in airfoil shape all aircraft parts such as struts, wheel fairing, etc. The two major contributors to parasite drag are the form drag and the skin-friction drag.
		Induced drag is inversely proportional to the speed (velocity) of the air.
		The aerodynamic efficiency is defined as the ratio between the lift coefficient and the drag coefficient.
	www.pilotsweb.com /principle/liftdrag.htm (1511 words)

	Compressibility Drag: Introduction
		The existence of supersonic local velocities on the wing is associated with an increase of drag due to a reduction in total pressure through shockwaves and due to thickening and even separation of the boundary layer due to the local but severe adverse pressure gradients caused by the shock waves.
		The drag increase is generally not large, however, until the local speed of sound occurs at or behind the 'crest' of the airfoil, or the 'crestline' which is the locus of airfoil crests along the wing span.
		Empirically it is found that the drag of conventional airfoils rises abruptly at 2 to 4% higher Mach number than that at which M= 1.0 at the crest (supercritical airfoil are a bit different as discussed briefly later).
	adg.stanford.edu /aa241/drag/cdcintro.html (1331 words)

	Aerodynamic Drag, Data for Airfoils, Wings, Aircraft, Automobiles (Site not responding. Last check: 2007-10-26)
		Drag coefficients (CD) in aerodynamics are drag forces normalized with a reference area, usually the frontal area, another projection area or the wetted area.
		Table 2 is a summary of typical drag coefficients of streamlined bodies.
		Table 3 is a summary of drag data for airborne systems and road vehicles.
	aerodyn.org /Drag/tables.html (323 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		Thus, zero-lift drag coefficient is reflective of parasitic drag which makes it very useful in understanding how "clean" or streamlined an aircraft's aerodynamics are.
		Parasitic drag experienced by an aircraft with a given drag area is approximately equal to the drag of a flat square disk with the same area which is held perpendicular to the direction of flight.
		In another comparison with the Camel, a very large but streamlined aircraft such as the Lockheed Constellation has a considerably smaller zero-lift drag coefficient (0.0211 vs. 0.0378) in spite of having a much larger drag area (34.82 ftÂ² vs. 8.73 ftÂ²), a testament to the skill of Lockheed's aerodynamicists.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Zero-lift_drag_coefficient (377 words)

	Drag Force
		The force exerted on a body moving in a medium like air or water depends in a complex way upon the velocity of the body relative to the medium, the viscosity and density of the medium, the shape of the body, and the roughness of its surface.
		This is the quadratic model of fluid resistance, in that the drag force is dependent on the square of the velocity.
		Note that the frictional force between two surfaces is an example of a situation in which the drag force is constant and does not depend upon the body's velocity or contact surface area.
	www.ac.wwu.edu /~vawter/PhysicsNet/Topics/Dynamics/Forces/DragForce.html (322 words)

	Sources of Drag in Supersonic Flow
		The third source of drag, which is a very significant portion of the drag in subsonic flight, is "lift-induced drag", or "induced drag".
		The entropy rise across a shock is related to the third power of the static pressure change, or the turning angle, whereas the drag coefficient in wave drag is proportional to the square of the turning angle.
		The drag by a shock of given static pressure ratio is thus considerably greater than the total wave drag due to several waves, each of small pressure ratio.
	www.adl.gatech.edu /classes/hispd/hispd03/sources_of_drag.html (1932 words)

	Songlin Zhu: Research3 (Site not responding. Last check: 2007-10-26)
		The effects of the groove’s position and depth on lift, drag and lift-to-drag ratio at zero angle of attack are shown in Figure l5-20.
		But as jet momentum coefficient was greater than 0.14, the effect of grooves on drag was more significant than that on lift, so the lift-to-drag ratio of the CCR with grooves was greater than that of the CCR.
		The maximum of lift-to-drag ratio was reached at B of 99 degree and jet momentum coefficient of 0.17.
	www.duke.edu /~slzhu/research/ccw/research4.html (2232 words)

	The Drag Coefficient
		The drag coefficient is a number that engineers use to model all of the complex dependencies of shape and flow conditions on rocket drag.
		As pointed out on the drag equation slide, the choice of reference area (frontal area or surface area) will affect the numerical value of the drag coefficient that is calculated.
		The drag coefficient contains not only the complex dependencies of object shape, but also the effects of air viscosity and compressibility.
	exploration.grc.nasa.gov /education/rocket/dragco.html (505 words)

	Air drag
		As is well-known, the drag force acting on an object which moves very slowly through a viscous fluid is directly proportional to the speed of that object with respect to the fluid.
		Wind tunnel measurements reveal that the drag coefficient is a strong function of speed for baseballs, as illustrated in Fig.
		The sudden drop in the drag coefficient is triggered by a transition from laminar to turbulent flow in the air layer immediately above the ball's surface.
	farside.ph.utexas.edu /teaching/329/lectures/node42.html (800 words)

	Model Rocket Drag Analysis, NAR R&D Report
		The drag measurements were made using a commercially available wind tunnel intended for experimentation at the high school and undergraduate college level.
		To measure the coefficient of drag, a model rocket (or plane or car) is placed in a wind tunnel with a controlled air flow.
		The derived table of drag coefficients should not be used for velocities above 80% the speed of sound (950 km/hr or 260 m/sec).
	web.syr.edu /~smdemar/rocketdrag.html (2689 words)

	Atkinsopht/Rowing/Oarblade Lift and Drag
		ROWING at first assumes an arbitrary drag coefficient from which an initial slip velocity is found from the force, blade surface, and water density.
		Increasing the drag coefficient (or blade surface area) increases blade efficiency by increasing drag near the ninety-degree point of the sweep.
		Because drag at the 90 degree sweep point may be more useful than lift at small attack angles let's begin with some simple, accurate, flat-on pure drag measurements of the currently popular forms in a range of surface area.
	www.atkinsopht.com /row/liftdrag.htm (2504 words)

	Drag coefficient
		Neutral drag coefficients were calculated from the TOGA-COARE bulk algorithm using 1 Hz 30m data.
		The drag coefficient vs winds adjusted to 10m is shown here.
		The slope of the drag dependence on U was used to adjust the local winds to Uaverage, and calculate Cdn from that, as in Enriquez (1994).
	www-ccs.ucsd.edu /~kate/bulk.html (660 words)

	SEMA.org \|\| Specialty Equipment Market Association - SEMA (Site not responding. Last check: 2007-10-26)
		The coefficient of drag of the pickup without its mirrors was 0.432—this is the baseline value in order to compare other conditions.
		Surprisingly, there was a decrease in the drag coefficient when the tailgate was lowered, with a value of 0.414, even though the drag coefficient experienced an increase when the tailgate was completely removed.
		Also, it is important to remember that drag depends on the size and shape of the vehicle, and therefore a Chevrolet, a Dodge, and a Ford pickup with the same cap might have different drag coefficients because of different design features.
	www.sema.org /Main/SemaOrgHome.aspx?ID=52546 (637 words)

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