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Topic: Supercritical airfoil

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	Airfoil - Wikipedia, the free encyclopedia
		An airfoil (in American English, or aerofoil in British English) is the shape of a wing or blade (of a propeller or ship's screw or sail) as seen in cross-section.
		Subsonic-flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, and often with camber.
		Sails are also airfoils, and the underwater fins of sailboats, such as centerboards are similar in cross-section and operate on the same principles as airfoils.
	en.wikipedia.org /wiki/Airfoil (349 words)

	Airfoil -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-05)
		Airfoils are also found in (A mechanical device that rotates to push against air or water) propellors, (An ardent follower and admirer) fans, (A mechanical device that compresses gasses) compressors and (Rotary engine in which the kinetic energy of a moving fluid is converted into mechanical energy by causing a bladed rotor to rotate) turbines.
		However, the airfoil shape ensures that lift is generated with the minimum of (The phenomenon of resistance to motion through a fluid) drag, so it is important for efficiency.
		The optimal design of airfoils has been much studied and is a key element in (The branch of mechanics that deals with the motion of gases (especially air) and their effects on bodies in the flow) aerodynamics.
	www.absoluteastronomy.com /encyclopedia/a/ai/airfoil.htm (456 words)

	Aerospaceweb.org \| Ask Us - Supercritical Airfoils
		What a supercritical airfoil is designed to do is delay the speed at which the compressibilty effect becomes significant so that drag will be reduced.
		The basic design approach behind these shapes is to flatten the upper surface of the airfoil to reduce flow acceleration and to use a highly cambered aft section to generate the majority of the lift.
		To give some idea of the practical benefit of the supercritical airfoil, Air Force and NASA researchers under the auspices of the Transonic Aircraft Technology (TACT) program modified a basic F-111 bomber and replaced the existing NACA 64-210 wing airfoil with a supercritical shape of equal thickness.
	www.aerospaceweb.org /question/airfoils/q0003.shtml (843 words)

	Supercritical wing - Wikipedia, the free encyclopedia
		A supercritical wing is a kind of wing designed to increase aircraft performance within the transonic speed range.
		The supercritical wing is still the number one choice for high-speed subsonic and transonic aircraft from the Airbus A380 to the Boeing F-15 fighter.
		A notable example of one such heavy-lift aircraft that uses a supercritical wing is the C-17.
	en.wikipedia.org /wiki/Supercritical_wing (287 words)

	Supercritical wing - Patent 4660788
		A supercritical wing of the variety in which the compression shock is stabilized is being improved by providing a suction device, substantially along the entire wing span, right at the chord station of the upper-wing surface where intercepting the sonic line.
		An airfoil as in claim 1, the means including one slot extending for approximately the entire wing span, the contour of the airfoil being modified toward a slight outward extension, resulting in a hypothetical kink in the slot area, to further stabilize the shock-producing area right at the slot.
		A supercritical wing is defined or commonly understood to be an airfoil designed for subsonic flights, but having a flow field along its upper surface which flow field includes an extended portion that is supersonic.
	www.freepatentsonline.com /4660788.html (3060 words)

	Supercritical Airfoils (Site not responding. Last check: 2007-11-05)
		Supercritical airfoils are designed to delay and reduce the transonic drag rise, due to both strong normal shock and shock-induced boundary layer separation.
		As compared with a conventional airfoil a supercritical airfoil has reduced amount of camber, an increased leading edge radius, small surface curvature on the suction side, and a concavity in the rear part of the pressure side.
		Design of supercritical airfoils has been made easier in recent years, due to the progress in theoretical methods for inverse design at transonic speeds.
	www.aerodyn.org /HighSpeed/supercritical.html (206 words)

	Types of Wings and Transonic Flow
		airfoils: increase in drag associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c).
		Because of the flattened upper surface of the supercritical airfoil, lift is reduced.
		Alternatively, at lower drag divergence Mach numbers, the supercritical airfoil permits a thicker wing section to be used without a drag penalty.
	www.centennialofflight.gov /essay/Theories_of_Flight/Transonic_Wings/TH20.htm (1457 words)

	Aerospaceweb.org \| Ask Us - Boeing 767 & 777 Airfoils
		On most traditional airfoil shapes, such as the early NACA series, this distribution tends to be concentrated towards the forward portion of the airfoil, as exemplified below.
		A new kind of airfoil was needed to improve performance at these high speeds, a shape called the supercritical airfoil.
		We therefore say that the supercritical airfoil is "aft-loaded" because the lift force is more significantly "loaded" onto the aft portion of the shape.
	www.aerospaceweb.org /question/airfoils/q0054b.shtml (440 words)

	Richard Kline & Floyd Fogleman: Airfoil (US Patents 3,706,430 & 4,046,338)
		The leading edge of the airfoil is defined by the apex of a wedge-shaped section that is formed by angular convergence of the upper surface and a generally planar portion of the under surface.
		As in the general case of airfoils that constitute aircraft wings, the relative air flow with respect to the airfoil is from the leading edge in direction generally parallel to the root section and rearwardly to the free trailing edge, and thence downstream in substantially the same general direction.
		The thickness of the airfoil gradually increased from the leading edge to approximately 50% of the chord to form the wedge-like section, at which point, the second surface was sharply projected in the direction of the first surface to form the step-like discontinuity.
	www.rexresearch.com /klinfogl/klinfogl.htm (8802 words)

	ch2-4
		The basic airfoil used on the number 2 airplane was the NACA 65-110, and both the Annular Transonic Tunnel and the 4 x 19-Inch Semi-Open High-Speed Tunnel programs had scheduled this section for their initial tests in anticipation of critically important comparisons.
		The term "supercritical" in its broadest sense means any speed beyond the critical Mach number, but as used by most of us in that period it meant speeds greater than the force-break speeds and extending upward into the sonic or low supersonic region.
		He also examined the inverted airfoil in the region of shock stall and beyond and found it to be generally as good as or superior to the normal attitude.
	www.hq.nasa.gov /office/pao/History/SP-445/ch2-4.htm (5041 words)

	Aerospaceweb.org \| Ask Us - Supercritical Airfoil Coordinates
		As we have explained previously, an airfoil is a special shape that defines the cross-section of a wing or other lifting body.
		Many classes of airfoils exist, some of which are further described in previous airfoil questions.
		A supercritical airfoil, an example of which is illustrated below, is merely a special class of airfoil shapes tailored for use at speeds near Mach 1.
	www.aerospaceweb.org /question/airfoils/q0127b.shtml (378 words)

	Home (Site not responding. Last check: 2007-11-05)
		Airfoil research slowed in the 1950s due to the development of supersonic and hypersonic planes and it wasn’t until 1965 that the next major breakthrough in airfoil design came.
		This airfoil moves the point at which the air reaches Mach1 further back towards the trailing edge of the airfoil so reducing drag.
		The supercritical airfoil was first tested by NACA on the Vought F8-A Crusader (see figure 9) and considerably reduced shock waves, and therefore drag, on the airfoil.
	www.bath.ac.uk /~en3jrm/airfoildesign/postww2.htm (292 words)

	Supercritical Airfoil
		An airfoil is the shape of a wing's cross-section.
		Whitcomb was already famous for developing the "Area Rule" of supersonic flight which won him the Collier Trophy and which resulted in some fighters of the mid 1950s having a pinch midway along their fuselage, like an hourglass.
		He proposed a new airfoil shape featuring a well-rounded leading edge, relatively flatter upper surface (not as curved or cambered as other wings) that pushed the critical Mach point farther back on the wings, and a sharply down-curving trailing edge that increased lift.
	www.centennialofflight.gov /essay/Evolution_of_Technology/supercritical/Tech12.htm (1176 words)

	Airfoil boundary layer and wake -- Experiments by Nakayama
		The experimental results indicate that the flow around the conventional airfoil is a minor perturbation of a symmetric flat-plate flow with small wake curvature and weak viscous-inviscid interaction.
		The flow around the supercritical airfoil is in considerable contrast with strong streamwise pressure gradients, non-negligible normal pressure gradients and large surface and streamline curvatures of the trailing-edge flow.
		In this case, the near-wake is strongly curved and intense mixing occurs between the retarded boundary layer of the upper-surface and the strongly accelerated one of the lower-surface.
	cfd.me.umist.ac.uk /ercofold/database/test11/test11.html (351 words)

	Airfoil (Site not responding. Last check: 2007-11-05)
		An airfoil (in American English, or aerofoil in British English) is the shape of a wing or blade (of a propeller or ship's screw) as seen in cross-section.
		Subsonic-flight airfoils have a characteristic shape, which is that of a curved streamline with a rounded leading edge and a sharp trailing edge.
		An airfoil in an inverted position will create a downward pressure on an automobile or other motor vehicle, improving its traction and reducing its likelihood of becoming airborne.
	www.worldhistory.com /wiki/A/Airfoil.htm (477 words)

	NASA - NASA Dryden Technology Facts - The Supercritical Airfoil
		An airfoil considered unconventional when tested in the early 1970s by NASA at the Dryden Flight Research Center is now universally recognized by the aviation industry as a wing design that increases flying efficiency and helps lower fuel costs.
		Called the supercritical airfoil, the design has led to development of the supercritical wings (SCW) now used worldwide on business jets, airliners and transports, and numerous military aircraft.
		Supercritical wing technology is now incorporated into the designs of commercial, business, and military aircraft around the world.
	www.nasa.gov /centers/dryden/about/Organizations/Technology/Facts/TF-2004-13-DFRC.html (1588 words)

	Bibliographie des DLR (LIDO) (Site not responding. Last check: 2007-11-05)
		Recent results from flutter experiments of the supercritical airfoil NLR 7301 at flow conditions near the transonic dip are presented.
		The airfoil was mounted with two degrees of freedom in an adaptive solid-wall wind tunnel, and boundary-layer transition was tripped.
		The time lag of the lift response to the pitching motion of the airfoil appears to be responsible for the characteristic shape of the transonic dip.
	www.dlr.de /lido/WB-AE/2004/1973132004.html (157 words)

	ON THE WING: A BUSINESS--CLASS JET
		A supercritical airfoil enhances an airplane's performance in a critical flight area--the transonic regime (speeds near Mach 1).
		Supercritical wings change the shape of the airflow by flattening the upper surface of the wing, which minimizes the effect of the shock wave.
		Flutter is defined as an unstable, self-generated oscillation of an airfoil and associated structure.
	www.sti.nasa.gov /tto/spinoff1998/t1.htm (783 words)

	F-8SCW EC73-3468: F-8 SCW in flight
		In this photograph a Vought F-8A Crusader is shown being used as a flying testbed for an experimental Supercritical Wing airfoil.
		The F-8 Supercritical Wing was a flight research project designed to test a new wing concept designed by Dr. Richard Whitcomb, chief of the Transonic Aerodynamics Branch, Langley Research Center, Hampton, Virginia.
		Compared to a conventional wing, the supercritical wing (SCW) is flatter on the top and rounder on the bottom with a downward curve at the trailing edge.
	www.dfrc.nasa.gov /gallery/photo/F-8SCW/HTML/EC73-3468.html (681 words)

	ch2-5
		He knew of the advantages of reduced camber for supercritical operation, but he was not aware of the special airfoil developed by Allen and recommended by Woersching to be used in the inverted attitude.
		The general attitude of most airfoil researchers of the forties was that shockless flows were a curiosity of the theoretician not likely to exist in real viscous flows.
		On problems of great complexity such as the supercritical airfoil this least sophisticated of all research techniques is likely to prove ineffective-unless the practitioner has truly unusual insights and intuitions.
	www.hq.nasa.gov /office/pao/History/SP-445/ch2-5.htm (2061 words)

	Airliners.net forum: Are Wings Shapes Made To Store Fuel?
		The success of supercritical airfoil sections used on current Airbus and Boeing airplanes is that they allow a successful compromise of these competing design requirements.
		The whole idea behind supercritical airfoils is to allow airfoils with higher t/c ratios to be used for a given amount of wave drag.
		The original concept of supercritical airfoils used a region of very rapid curvature near the nose which created expansion waves that were tuned to weaken the shock wave.
	www.airliners.net /discussions/tech_ops/print.main?id=113122 (2757 words)

	Concept to Reality
		Thus, two medium-speed airfoils (13- and 17-percent thick) were developed to fill the gap between the low-speed airfoils and the high-speed supercritical airfoils.
		The 6-series airfoils were not as operationally successful as low-drag airfoils because the riveted construction techniques employed at the time introduced physical disturbances that disrupted laminar flow.
		Similar to supercritical airfoils, as previously mentioned, a large amount of aft camber is required to achieve high maximum lift on airfoils with extensive laminar flow.
	oea.larc.nasa.gov /PAIS/Concept2Reality/airfoils.html (3789 words)

	X-29
		The concepts and technologies the fighter-size X-29 explored were the use of advanced composites in aircraft construction; variable camber wing surfaces; the unique forward-swept wing and its thin supercritical airfoil; strake flaps; close-coupled canards; and a computerized fly-by-wire flight control system to maintain control of the otherwise unstable aircraft.
		Developed by NASA and originally tested on an F-8 at Dryden in the 1970s, supercritical airfoils flatter on the upper wing surface than conventional airfoils delayed and softened the onset of shock waves on the upper wing surface, reducing drag.
		Wing trailing edge actuators controlling camber are mounted externally in streamlined fairings because of the thinness of the supercritical airfoil.
	www.fas.org /man/dod-101/sys/ac/x-29.htm (1960 words)

	NASA Dryden Fact Sheets - F-8 Supercritical Wing (Site not responding. Last check: 2007-11-05)
		Compared to a conventional wing, the supercritical wing (SCW) is flatter on the top and rounder on the bottom with a downward curve at the trailing edge (see illustration).
		The supercritical wing was a new tailoring of an airfoil design that delayed the formation and reduced the strength of the shock wave over the wing just below and above the speed of sound.
		Flown as the SCW testbed by NASA from 1971 to 1973.
	trc.dfrc.nasa.gov /Newsroom/FactSheets/FS-044-DFRC.html (666 words)

	Bibliographie des DLR (LIDO) (Site not responding. Last check: 2007-11-05)
		For the present investigations of dynamic stall a supercritical airfoil was chosen.
		This new airfoil designed by DLR will be used in dynamic stall control research activities (project ADASYS) planned for the near future: The leading edge portion of the airfoil will be drooped down dynamically to improve dynamic stall characteristics on the retreating side during blade motion.
		Dynamic stall experiments on the rigid supercritical airfoil have first been carried out in the DNW-TWG transonic wind tunnel with a 1mx1m cross section of the test section and adaptive top and bottom -walls.
	www.dlr.de /lido/SM-AS/2003/1935682003.html (210 words)

	Articles - Airfoil (Site not responding. Last check: 2007-11-05)
		Sails are also airfoils, and the underwater fins of sailboats, such as centerboards, are also lifting foils and operate on the same principles as airfoils (technically they should called hydrofoils, but this term has already been taken; generally they are just referred to as "foils").
		Airfoils though are more efficient, generating lift with the least drag.
		While sharper leading edged airfoils produce stiffer and lighter wings, large rounder edges increase wing volume for fuel.
	www.seekj.com /articles/Airfoil (360 words)

	Seek 'Airfoil' related info here. (Site not responding. Last check: 2007-11-05)
		The supercritical airfoil, first developed by a NASA aerodynamicist in the 1960s, An airfoil is the shape of a wing's cross-section.
		In this paper we are concerned with the generalized airfoil equation, which governs the pressure across an airfoil oscillating in a wind tunnel.
		The camber of an airfoil is the curve of its upper and lower surfaces.
	netinfoseek.com /?q=airfoil (1025 words)

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