Lift to drag ratio

Lift to drag ratio - Factbites
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Topic: Lift to drag ratio

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In the News (Thu 17 Dec 09)

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	Lift-to-drag ratio
		A "better" L/D ratio is one of the major goals in wing design, since a particular aircraft's needed lift doesn't change, delivering that lift with lower drag leads directly to better fuel economy, climb performance and glide ratio.
		Like all things in aeronautical engineering, the lift-to-drag ratio is not the only consideration for wing design.
		Applications of low lift to drag ratio aerobrakes using angle of attack variation for control (SuDoc NAS 1.15:103544)
	www.freeglossary.com /L/D_ratio

	Autumn Breeze version 1.0 Sci. 1 glider project
		The maximum ratio between horizontal and vertical displacement is equal to the maximum lift-to-drag ratio (L/D), or the best glide ratio.
		The ratio can be found through an actual test flight distances, or by calculating the lift and drag of the glider given the coefficient of lift ( C
		Parasitic drag refers to drag caused by both frictional and pressure drag, thus this form of drag is based primarily on the shape and size of the glider.
	www34.brinkster.com /nightning/glider2.html

	Lift and Drift
		Now if the lift [generated by an air foil on the upper arms is] transmitted to the point a and applied at right angles to arms ac, the [drag fingers] will [move] to the position indicated by the dotted lines and the pressure exerted will be as ax is to ay, i.e.
		By plotting the lift and the drag of each foil against the angles of attack, they were able to see and compare the efficiency of the wing shapes.
		The Wright wind tunnel experiments marked the first time that anyone had measured the lift and drag produced by various wing shapes with sufficient accuracy for them to be of any use in aircraft design.
	www.first-to-fly.com /Adventure/Workshop/lift_and_drift.htm

	Chapter0
		Clearly, then, the lift to drag ratio is the best when the angle of attack is as small as is possible, since the reciprocal of the sine approaches infinity when the sine approaches zero.
		Whether viewed as proportional to the reciprocal of the sine or as the more accurate cotangent, the lift to drag ratio is an extremely important measure of the ability of the aircraft wings to create what is known as "flight".
		In other words, it has both a lift and a drag component to it.
	www.integener.com /SABTSKManuscript/Chapter0.htm

	Songlin Zhu: Research3
		With these parameters, the lift-to-drag ratio L/D could be obtained too.
		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.
		Fig 17 Effect of groove's position on lift-to-drag ratio.
	www.duke.edu /~slzhu/research/ccw/research4.html

	Waverider
		A waverider is a hypersonic aircraft design that improves its supersonic lift-to-drag ratio by producing a lifting surface built out of the shock wave s being generated by its own flight, a technique known as compression lift.
		The primary purpose for this design is to create a light-weight disposable lifting surface for interplanetary spacecraft to use while maneuvering over planets with an atmosphere.
		The underside, which is inclined to the flow at a high angle of attack, creates lift in reaction to the vehicle wedging the airflow downwards.
	www.worldhistory.com /wiki/W/Waverider.htm

	Lift and Drag Curves- level 3
		The characteristics of any particular airfoil section can conveniently be represented by graphs showing the amount of lift and drag obtained at various angles of attack, the lift-drag ratio, and the movement of the center of pressure.
		Many tests were run by the NACA, the predecessor to the NASA, and a booklet, NACA Report 824 (1945) was created to give the relation of coefficient of lift, coefficient of drag, pressure and moment coefficients (not shown above) for many different types of airfoil.
		Hence drag is the price we pay for lift.
	www.allstar.fiu.edu /aero/lift_drag.htm

	NASA Quest > Aerospace Team Online
		For a given lift-to-drag ratio, if you increase lift, drag increases.
		Lift is the upward force allowing the aircraft to fly.
		Several factors influencing lift can be controlled by the aircraft's wing design.
	quest.arc.nasa.gov /aero/teachers/foa.html

	Thrust to Weight Ratio
		Just as the lift to drag ratio is an efficiency parameter for total aircraft aerodynamics, the thrust to weight ratio is an efficiency factor for total aircraft propulsion.
		Lift is directed perpendicular to the flight path and drag is directed along the flight path.
		Lift and drag are aerodynamic forces that depend on the shape and size of the aircraft, air conditions, and the flight velocity.
	www.lerc.nasa.gov /WWW/K-12/airplane/fwrat.html

	Investigation of Effects of Surface Roughness on Symmetric Airfoil Lift and Lift-to-Drag Ratio - Storming Media
		Based on experimental studies, the Russian researchers identified a protuberance geometry on a low aspect ratio wing which created both additional lift and an improved lift-to-drag ratio for a given angle-of-attack over the low to moderate angle-of-attack region.
		Results indicated that the variation of the aerodynamic lift and the lift-to-drag ratio for symmetric airfoils and wings populated with protuberances is due to the increased pressure induced by a recirculation region downstream of the protuberance.
		Abstract: This research investigated the effects of surface roughness in the form of protuberances on the lift and lift-to-drag ratio of an airfoil with a NACA 0015 profile.
	www.stormingmedia.us /56/5600/A560063.html

	Untitled Document
		The Phoenix's optimal LIFT to DRAG RATIO generated from SST (SHAPED SPAR TECHNOLOGY) is not attainable though current single leading edge designs.
		One is therefore faced with the challenge of creating the desired amount of lift without too much resulting drag.
		Drag is defined as a force exerted on an airfoil in a direction opposite to the foil's path of travel.
	www.surfcompaniet.se /phoenix.html

	Re: Lift-to-Drag Ratio?
		Now of course the pressures in these regions are not constant so to get a more exact answer you would integrate all the pressures over the entire surface of the aircraft (not just the wings) to arrive at one force which is the net superposition of lift and drag.
		Remembering that ahead of the wing is the shock wave (Pw) and ahead of that ambient air (Pa) then to a first approximation: [(Pa - Pw) + (Pw - Pb)] * Av = (Pa -Pb) * Av = Drag, where Av is the cross-sectional area of the wing perpendicular to the direction of motion.
		The lift comes from Angle of Attack (AOA), which > >> causes induced drag.
	www.usenet.com /newsgroups/rec.aviation.homebuilt/msg05790.html

	Is the lift/drag ratio a function of the weight?
		Your thinking is correct: Lift to drag depends on the weight, because
		Is the lift/drag ratio a function of the weight?
		Subject: Is the lift/drag ratio a function of the weight?
	wwww.usenet-replayer.com /data/sci/aeronautics/1157.html

	Minimum Induced Drag of Sail Rigs and Hydrofoils
		Although the resulting lift distribution produces more drag for a given span than the elliptical lift distribution, the lower moments allowed the span to be increased which reduced the induced drag approximately 14% while keeping the same moment as for the classic elliptical planform.
		Note that this makes it possible to take into account such effects as the loss of lift due to separation at the leading edge caused by the mast, by simply making the chord larger where the section lift curve slope is less.
		Since the problem is linear, once the lift coefficient, CL, is found for a unit induced velocity, the induced velocity required to achieve any desired CL can be found by taking the ratio of the lift coefficient for unit velocity to the desired lift coefficient.
	www.tspeer.com /Planforms/Planar.htm

	Lawrence Hargrave, Australian aviation pioneer, 1850-1915
		The Hargrave-designed box kite, with its improved lift-to-drag ratio, was to provide the theoretical wing model that allowed the development of the first generation of European (and American) airplanes.
		During the course of his experiments he found out that a curved surface had twice the lift as a flat one, and next he discovered that a kite with two separated "cells" or double planes, had the greatest stability and oaring power.
		The French (who thought that France was the cradle of aviation) freely acknowledged Hargrave's influence: Alberto Santos-Dumont was the first European to fly a heavier-than-air machine constructed of Hargrave box kites in 1906.
	www.ctie.monash.edu /hargrave/hargrave_bio_large_print.html

	Pilot's Web The Aviators' Journal - More About Lift and Drag
		The lift and the drag formulas for a finite wing offer a valuable tool for analyzing aerodynamic relationships.
		The air velocity is a major contributor to lift and drag because both are proportional to square of the velocity.
		The aerodynamic efficiency is defined as the ratio between the lift coefficient and the drag coefficient.
	www.pilotsweb.com /principle/liftdrag.htm

	Lift to Drag (L/D) Ratio
		Because lift and drag are both aerodynamic forces, we can think of the L/D ratio as an aerodynamic efficiency factor for the aircraft.
		The tangent of the glide angle is also related to the ratio of the drag, D, of the the aircraft to the lift, L.
		The lift divided by drag is called the L/D ratio, pronounced "L over D ratio." From the last equation we see that the higher the L/D, the lower the glide angle, and the greater the distance that a glider can travel across the ground for a given change in height.
	wright.nasa.gov /airplane/ldrat.html

	SetSail.com - the serious cruising sailor's website
		If you get all the issues worked out, it will yield a much better lift-to-drag ratio.
		On the other hand, either product is going to be orders of magnitude better than the sails he is replacing and the 7 batten construction and low aspect ratio are both in the plus column for shape retention.
		Most people also find that there is less weather helm and less heel, due to substantially reduced induced drag and improved drag angles.
	www.setsail.com /c_central/faqs/faq2.html

	WingAnalysis Plus: An Integrated Airfoil and Wing Analysis Software Package
		It provide vital design parameters such as total lift, total drag (induced and profile), bending moments and maximum lift/drag ratio.
		It computes lift, vortex drag, profile drag, weight, center of gravity location measured from the root leading edge (LCG), center of gravity measured vertically from root location (VCG) and other performance parameters in a few seconds for each design.
		Lift Coefficient Comparison for 3 Wings with Different Aspect Ratios.
	www.hanleyinnovations.com /waplus.html

	Russian Aviation Page: Ekranoplans (WIGs) - bold and beautiful
		Induced drag (drag due to the lift) of wing is considerably reduced if the altitude of the aircraft is similar to the chord of the wing.
		While you may not need much power in operate in ground effect, you much more it to get up to speed on water to lift off.
		You need to make sure it can operate in the marine environment, but still be light enough to lift off.
	aeroweb.lucia.it /~agretch/RAFAQ/WIG.html

	Re: Lift-to-Drag Ratio?
		So, the more lift you have for a given amount of drag the less thrust you need to achieve a given speed.
		A wing with a higher L/D will give you "X" amount of lift with less drag (L/D is just "amount of lift" per "amount of drag").
		To maintain straight and level flight you need "X" amount of lift to hold up the wieght of your aircraft.
	www.usenet.com /newsgroups/rec.aviation.homebuilt/msg06162.html

	GrandPrix.com > Features > Technical > Chalk and Cheese
		It is impossible to quantify the differences in downforce and Lift/Drag ratio.
		Ferrari's markedly improved performance relative to McLaren at Monza this year, probably had more to do with the elimination of the curbs, over which McLaren had always excelled and so been able to take a straighter line through the chicanes.
		The key performance parameters, weight, power, tires aerodynamic downforce, and aerodynamic drag have not had their performance limiting regulations significantly changed for a couple of years.
	www.grandprix.com /ft/ftpw007.html

	Encyclopedia article on Space Shuttle program [EncycloZine]
		This large 'cross-range' capability meant the craft had to have a greater lift to drag ratio than originally planned.
		These were quite large, weighing an estimated 40,000 pound (18 t), and needed to be put into polar orbit, which requires more energy to get to than the more common low Earth orbit.
		This required the addition of bigger, heavier wings.
	encyclozine.com /Space_Shuttle_program

	pof1.txt
		If you increase the propeller pitch during glide with idle powwer at constant IAS the lift to drag ratio will: A increase and the ROD will increase B decrease and the ROD will decrease C increase and the ROD will decrease D decrease and the ROD will increase 5.
		The lift to drag ratio provides directly to: A distance for horizontal flight B distance for climb up to a certain altitude C glide distance from a given altitude D glide distance from a given altitude at zero wind 31.
		Shoch induced seperation results in: A decreasing lift B decreasing drag C increasing lift D constant lift 6.
	members.home.nl /cboer/pof1.txt

	ORNITHOPTER and HANG GLIDER
		Lift-to-drag ratio is a ratio of lift (at steady-state flight it is equal to the weight of the vehicle) to the force of its aerodynamic drag.
		The study of birds shows that a large albatross, because of its streamlining, has the highest lift-to-drag ratio of any bird, but even a small swallow has a high lift-to-drag ratio.
		The large birds compensate for a shortage of power by an increase of lift-to-drag ratio and a change of flight technique.
	ancom.g.com.ua /eng/or002.htm

	How to measure efficiency of traction kites and sailing crafts.
		The lift to drag, L/D, for a traction kite can be measured by having it flown back and forth close to the ground by a stationary person.
		It is also described how you can measure pull and coefficient of lift for a traction kite.
		The L/D ratio for other sailing crafts can be measured in an equivalent way.
	home.swipnet.se /ansar/measure.html

	CNI News 21.1
		"At those high speeds, things happen so quickly that the pilot cannot control the aircraft as easily as at subsonic speeds." The waverider was chosen as the testbed for the neural networks because the configuration has an inherently high hypersonic lift-to-drag ratio.
		If neural networks can control this "worst-case scenario" configuration, then they should be able to handle virtually any other configuration.
	www.sacred-texts.com /ufo/cni0211.htm

	Shuttle Columbia Disaster; Wrong Place, Wrong Time!
		The orbiter is designed with a double-delta wing configuration in which the forward placed delta wing creates vortices that flow smoothly over the main delta wing which creates greater lift and reduces drag.
		With this lift-to-drag capability, the orbiter is able to maneuver from side-to-side at a range of 2000 km (1240mi).
		The Double Delta Wing of the Shuttle with increased drag and resistance might have been prone to problems with increased ionization where the vortexes occur (the point where the wing angles as seen in wind tunnel testing of another Double-Delta wing aircraft in the picture below on the right).
	www.superforce.com /shuttle

	Roshawn Johnson
		� The best lift to drag ratio was found by trial and error using the lifting line program on the U.
		We found the lift to drag ratio to be the largest at 30.89, at
		We then found the angle of attack that gave us the required lift coefficient, this was the angle of attack needed to fly straight and level.
	www.prism.gatech.edu /~gtg316g/final.htm

	Peter Lynn Kites
		Lift to Drag ratio (LTD) is defined as the ratio of the lift minus weight to the drag of the kite.
		The lift to drag trend line was converted back to an equivalent line angle and the droop angle of a line under equivalent load and wind conditions was subtracted before recalculating as a lift to drag ratio.
		To do this, the lift to drag ratio of the kite-line system (LTDg) was determined and a trend line was taken from this.
	www.peterlynnkites.com /web/1archive/pages/testrig.htm

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In the News (Thu 17 Dec 09)