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	Mach_Number.htm
		Mach number has been tossed around so often in the popular press since the 1950's that the word has seeped in to the public argot.
		The Mach number, named after the Austrian scientist Ernst Mach (1836-1916), is the ratio of a velocity of an object in a fluid medium to the speed of sound in the medium.
		The Mach number at which compressibility effects become large and drag begins to rise very rapidly is called the "drag divergence" Mach number.
	www.geocities.com /CapeCanaveral/Galaxy/4707/Aeronotes/Mach_Number.htm (808 words)

	Mach number
		A unit of speed, named after the Austrian physicist Ernst Mach (1838-1916), equal to the ratio of the speed of a moving object to the speed of sound in the surrounding medium under ambient conditions.
		Because the speed of sound varies, a particular speed at sea level expressed as a Mach number would be faster than the same speed at 30,000 ft (9,144 m), which would be faster than the same speed at 40,000 ft (12,192 m).
		A "critical Mach number" is the speed of an aircraft (below Mach 1) when the air flowing over some area of the airfoil has reached the speed of sound.
	www.daviddarling.info /encyclopedia/M/Mach_number.html (369 words)

	critical Mach number@Everything2.com
		The critical Mach number of a wing is the speed, relative to the speed of sound, at which the flow over the top of the wing exceeds Mach 1.
		The critical Mach number varies with wing geometry and angle of attack, but a number around 0.6 or 0.7 at 0 angle of attack is typical.
		Because the critical Mach number and the drag divergence Mach number are often fairly close, it is usually desirable to lower the critical Mach number by using swept wings.
	www.everything2.com /index.pl?node_id=1331473 (254 words)

	ch5-2
		The critical Mach number is defined as the aircraft flight Mach number at which the local Mach number over some portion of the aircraft, such as the upper surface of the wing for example, equals unity; that is, the flow at this point has reached sonic velocity.
		The Mach number at which the lift begins to show a sharp decrease becomes smaller as the angle of attack is increased since the critical Mach number decreases with increasing angle of attack.
		For example, at a Mach number of 0.4, the lift coefficient increases from 0.2 to about 0.72 as the angle of attack varies from 0 to 5 whereas, at a Mach number of 0.8, increasing the angle of attack from 0 to 5 results in an increment in lift coefficient of only about 0.2.
	www.hq.nasa.gov /office/pao/History/SP-468/ch5-2.htm (4650 words)

	Flight 101 - Flow Effects and Flight - free Suite101 course
		The Mach number is a measure of the ratio of the airplane speed to the speed of sound.
		There eventually occurs a freestream Mach number called the critical Mach number at which a sonic point appears somewhere on the airfoil surface, usually near the point of maximum thickness and indicates that the flow at that point has reached Mach 1.
		As the free-stream Mach number is increased beyond the critical Mach number and closer to Mach 1, larger and larger regions of supersonic flow appear on the airfoil surface.
	www.suite101.com /lesson.cfm/17507/821/3 (2126 words)

	ch10-4
		The critical Mach number of a wing is the flight Mach number of the aircraft at which the local Mach number at some point of the wing becomes 1.0.
		This relationship is based on the assumption that the critical Mach number of the wing is controlled only by the flow normal to the leading edge and is independent of the Mach number parallel to the leading edge.
		The effect of sweepback on the critical Mach number of finite wings is usually analyzed in terms of a wing of given aspect ratio and airfoil thickness ratio in the free-stream direction.
	www.hq.nasa.gov /office/pao/History/SP-468/ch10-4.htm (5875 words)

	Assignment #2 (Site not responding. Last check: )
		Find the critical Mach number of the airfoil used for the wing at mid-semi-span, and plot this against angle of attack.
		The center of pressure distribution plot for the airfoil at the mid-semi-span for a 1.8° angle of attack at Mach 1.5.
		Critical Mach number versus angle of attack for the biconvex airfoil.
	www.prism.gatech.edu /~gte230w/Assignment2.htm (1922 words)

	Aerospaceweb.org \| Ask Us - Supercritical Airfoils
		Thus, an aircraft flying at half the speed of sound is said to be flying at Mach 0.5 while an aircraft flying at the speed of sound is said to be flying sonic, or at Mach 1.
		Although the exact range of transonic Mach numbers will vary for different aircraft configurations and operating conditions, the transonic regime is generally said to be between Mach 0.7 or 0.8 and Mach 1.2 or 1.3.
		These airfoils have critical Mach numbers very close to one (hence the term supercritical) thereby delaying and reducing the large increase in drag due to wave drag.
	www.aerospaceweb.org /question/airfoils/q0003.shtml (843 words)

	High speed Aerodynamics
		In this section we will be concerned only with transonic flows past airfoils, wings and wing-bodies, although the problem is more general, since it includes wedges, slender bodies of various type, helicopter rotor blades, aeronautic propellers, nozzle flows, inlets, and other internal flows.
		The critical Mach number is the free stream Mach number at which sonic flow first appears on the airfoil/wing.
		Critical Mach numbers can be estimated in several ways, including the methods of Relf-Jacobs, Von Karman, Prandtl-Glauert, and Temple-Yarwood.
	aerodyn.org /HighSpeed/highspeed.html (843 words)

	Critical Mach Number
		Thus, the Mach number of the flow increases and then decreases.
		The magnitude of this change depends on the airfoil shape and the angle of attack.
		is a value of the freestream Mach number.
	www.adl.gatech.edu /classes/hispd/hispd04/Critical_Mach_Number.html (151 words)

	Aerodynamics Example #1
		In the field of aerodynamics, airspeeds are usually stated in terms of Mach number, which is the local airspeed divided by the local speed of sound.
		For example, assume we are considering airflow at a point, say, "A" on the surface of an airfoil.
		Assume you are trying to determine the critical Mach number of the NACA 0012 airfoil.
	www.akiti.ca /Mcrit.html (453 words)

	Dictionary : Speed_of_Sound_and_Mach_Numbers
		The Mach number (M) refers to the method of measuring airspeed that was developed by the Austrian physicist Ernst Mach.
		Because the speed of sound varies, a particular speed at sea level expressed as a Mach number would be faster than the same speed at 30,000 feet (9,144 meters), which would be faster than the same speed at 40,000 feet (12,192 meters).
		In other words, Mach 2 at sea level is a greater number of miles per hour (or kilometers per hour) than Mach 2 at 30,000 feet, which is a greater number of miles per hour than Mach 2 at 40,000 feet.
	www.centennialofflight.gov /essay/Dictionary/sound_barrier/DI94.htm (315 words)

	Dassault Falcon Aircraft / What's New / Falconer Online
		At.80 Mach cruise, the Falcon 7X's buffet onset boundary is 20 percent higher than the 900EX, thus allowing the 7X to fly efficiently at higher altitudes.
		Even though the aircraft's cruise speed or freestream Mach number is well below the speed of sound, when airflow over some part of the airframe accelerates to Mach 1, the aircraft is said to have reached its critical Mach number.
		If critical Mach is the speed at which localized airflows reach supersonic speeds, then a supercritical wing is one designed to delay the onset of supersonic airflows, and to be capable of flight above the critical Mach number without significant drag penalty.
	www.dassaultfalcon.com /whatsnew/falconer_article.jsp?DOCNUM=29390&IDOCNUM=29388 (2278 words)

	Concept to Reality
		The relatively small amount of lift lost by reducing the curvature of the upper surface of the airfoil is regained and substantially augmented by the larger extent of supersonic flow on the upper surface and by incorporating a substantial camber into the rear portion of the airfoil.
		He hypothesized that the increase in Mach number was caused by delayed shock-induced separation, and he immediately envisioned an application to the swept-wing subsonic transport.
		Initial wind-tunnel tests by North American Rockwell, Columbus Division, of wings with this range of thickness values indicated that the drag-divergence Mach number of a 17-percent-thick supercritical airfoil shape was equal to that for a conventional 12-percent-thick airfoil, that the buffet onset was considerably higher, and that the low-speed maximum lift was increased considerably.
	oea.larc.nasa.gov /PAIS/Concept2Reality/supercritical.html (3971 words)

	[No title] (Site not responding. Last check: )
		The level at which the horizontal mean free path of an atmospheric particle equals the scale height of the atmosphere.
		] The ratio of the critical pressure of a nozzle to the admission pressure of the nozzle (equals 0.53 for gases).
		] The volume occupied by one mole of a substance at the liquid-vapor critical point, that is, at the critical temperature and pressure.
	www.accessscience.com /Dictionary/C/C57/DictC57.html (1854 words)

	ScienceWeek
		Mach's close critical analysis of the empirical value of physical concepts and his insistence that they must justify their use helped produce the atmosphere in which special and general relativity, and later quantum theory, could be conceived.
		In an annotated narrative, Mach dissects the conceptual innovations and presuppositions that marked the history of the science of motion, from its prescientific roots through the late 19th century.
		The authors focus on statements by Ernst Mach (1838-1916) that often preface discussions of Mach's principle,(2) and examine the internal consistency of Mach's views and their validity in the light of classical physics that Mach knew(3) in 1912, but without using special relativity (SR), which Mach rejected.
	scienceweek.com /2004/sa040507-6.htm (1543 words)

	The Airplane
		Based on evidence that thin wings, with higher critical Mach numbers, retained more effective lift in the transonic region, the NACA ultimately decreed that Bell should produce two sets of wings which would be interchangeable on each of the test aircraft: one set with an eight-percent and the other with a ten-percent thickness-chord ratio.
		The impact of all of this on the aircraft's design was critical: the vehicle's landing weight was increased by one ton, while fuel capacity was reduced from 8,160 pounds to an estimated 4,680 pounds and, instead of 4.2 minutes, engine burn time was limited to just 2.5 minutes.
		Beyond that Mach number, of course, the flight re-searchers who were about to engage in the test program would be on their own.
	www.cebudanderson.com /airplane.htm (2299 words)

	WW2-fighter and critical Mach speed - Aircraft of World War II - Warbird Forums
		The critical Mach number for the P-38 was.68/.70 one of the earliest of all the topline fighters in WWII.
		But that also was far beyond it´s critical Mach number (..during the dive the Spit was still able to roll a bit thanks to it´s wing).
		I found some interesting calculations of the Ho-229 design: The V1 (unpowered glider) had a critical Mach number of 0.84, but the V-2 has to be redesigned because of the Jumo 004, which did not fit in the airframe.
	www.ww2aircraft.net /forum/aviation/ww2-fighter-critical-mach-speed-802.html#post47592 (2281 words)

	Types of Wings and Transonic Flow
		The critical Mach number (at which a sonic point appears) and the drag-divergence Mach number are delayed to higher values; Sweep forward or sweepback will accomplish these desired results.
		Substantial increases in the critical Mach number (the subsonic Mach number at which sonic flow occurs at some point on the wing for the first time) occur when using an aspect ratio less than about four.
		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)

	Critical Mach Number
		This effect is shown in the diagram to the left.
		The aircraft Mach number at which the airflow first reaches the speed of sound is called the Critical Mach number.
		The normal shock waves are the main source of increased drag during Transonic flight.
	selair.selkirk.bc.ca /aerodynamics1/High-Speed/Page2b.html (165 words)

	NACA0012 Airfoil Drag Rise - Mach 0.50 (Site not responding. Last check: )
		Red represents regions of high Mach number (mostly on the upper surface where the flow is being accelerated) and blue represents regions of low Mach number (mostly at the stagnation point regions in the leading and trailing edge areas).
		The sonic line (countour line where the Mach number is exactly 1.0) is shown as a faint white line when sonic flow exists.
		Drag divergence occurs somewhere between Mach 0.65 and 0.70 for this airfoil.
	adg.stanford.edu /aa241/drag/dragrise.html (375 words)

	theory
		The mach number, the relation of flight speed to the speed of sound, was stated with the resistant estimation.
		Therefore the flight mach number, at which locally the speed of sound occurs, is called critical and the speed range beginning with it transonic (to approximately mach number 1.3).
		The influence of the wing-tapering on the shifting of the critical mach number is not yet investigated, but is, with an increase of the tapering, to be expected, which is especially prominent in the delta wing.
	www.nurflugel.com /Nurflugel/Horten_Nurflugels/theory/body_theory.html (6318 words)

	Transonic Airfoils for Propellers (Site not responding. Last check: )
		This word arises from the "critical Mach number", which is the Mach number at which the shock wave starts to form on a given airfoil.
		The thin section is said to have a "higher critical Mach number" In crossing the shock wave, the air becomes heated, and its pressure increases.
		As Mach number is increased, the lift-curve slope (lift vs angle-of-attack) actually increases up to the critical Mach number, then drops off.
	www.supercoolprops.com /articles/transonic.php (2110 words)

	[No title]
		The speed at which the local velocity of the air flowing over an airfoil reaches Mach 1 is called the "critical" Mach number.
		Since the local velocity of the air at this "critical" airspeed has reached or exceeded Mach 1, shock waves begin to form as a means of pressure recovery returning the flow to a subsonic velocity.
		In other words, almost any airfoil will form shock waves between Mach 0.6-0.7 and the model propellers we use typically employ airfoils that have high critical Mach numbers around 0.55 to 0.6 because of the thick sections that are used (thickness to chord ratios > 10%).
	www.mini-iac.com /EditModule.aspx?tabid=71&mid=475&def=News%20Article%20View&ItemId=2 (732 words)

	Komet Me163 - Chief test pilot Rudy Opitz tells it like it was - Flight Journal.com Page 6 (Site not responding. Last check: )
		The primary reason for the wing sweep was to improve the pitch moment arm of the elevons rather than to increase the critical Mach number of the airplane.
		The “critical Mach number” of the airplane is the flight Mach number at which the local flow first goes supersonic on the wing.
		Alexander Lippisch was aware of the causes of Mach tuck and tried to design the operational Me 163B to have as high a critical Mach number as possible.
	www.flightjournal.com /articles/me163/me163_6.asp (1276 words)

	Aerospaceweb.org \| UCAV - Aerodynamics
		An initial LE angle of 48° was selected since it is similar to that used on the wing of the F-22 fighter.
		However, the wing design was later optimized to reduce drag during the Mach 0.9 ingress/egress segments.
		The NACA 66-008 was chosen for the outboard wing because (a) its critical Mach number is less than the maximum Mach number specified by the RFP and (b) its maximum thickness is closer to the middle which better suits the structural design.
	www.aerospaceweb.org /design/ucav/aerodynamics.shtml (563 words)

	Wing-Fuselage Configuration
		In the Mach number range (0.9-0.95), there exists a critical Mach number for which the flow returns to a steady state.
		Furthermore, the flow is found to be governed by two instability processes in the Mach number range (0.75-0.8), where, apart from the von Kàrmàn mode (mode~I), a lower frequency mode~II appears, due to the formation of weakly supersonic alternating zones in the region upstream of the aerofoil, related to the buffeting phenomenon.
		When the Mach number is increased, the shock wave is pushed further downstream, interact with the wake vortices and the upstream flow becomes steady.
	www.aqflow.com /PROJECTS/transonic.html (344 words)

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