Talk:Mach number

message: I cannot fully agree to the below comments made to the pronounciation of the surname "Mach". During all my life, including my studies of aeronautics in Germany, I have never heard anybody pronouncing his name with a long "a". It is indeed to be pronounced like the german imperative of the 2nd person of "machen" ("do!"), which is with a short "a", like in the english word "duck". The "ch" at the end however is the bit that most non-german speakers will find most difficult to pronounce. It cannot be described in written form, but it is correct that it does not sound like "ck".
Regards from Germany,
Christian  —Preceding unsigned comment added by 195.124.114.36 (talk) 15:53, 12 August 2008 (UTC)
replies: text: But "Mach" (of Ernst) has got a long "a", and "Mach" in "Mach etwas" a short one. Other than that, I agree, it's like "Bach". "Mack" or "Mock" are nonsense. 80.75.192.71 08:38, 18 July 2007 (UTC)
replies: text:  Mach is pronounced with Hard ch (), same as J.S.Bach, it is named after Austrian physicist Ernst Mach, both are german names. Only some ignorant clod could use ill-sounding form like "mack". Why is it even mentioned in the article?? -- IEEE (talk) 02:29, 28 September 2008 (UTC)
replies: text: Well, if you happen to speak a southern British dialect which doesn't use that [x] phoneme, it's usually much more comfortable to use "mack". Especially since with the long vowel you could confuse it with the word 'mark'. Either way, I agree that the pronunciation issue is irrelevant.--81.156.177.239 (talk) 21:11, 3 January 2009 (UTC)
thread_title:  Pronunciation 

message: :When an aircraft exceeds Mach 1 a large pressure difference is created just in front of the aircraft. This pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape. It is this shock wave that causes the sonic boom heard as fast moving aircraft travels over head.
What was wrong with this paragraph, and how can it be fixed? AxelBoldt 00:27 Oct 3, 2002 (UTC)
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Removed warp speed reference.  It's not correct even in the ST universe. Roadrunner 17:58, 30 Mar 2004 (UTC)
thread_title:  When an aircraft exceeds Mach 1... 

message: Wanting opinions before making an edit I'm unsure of: Would it be beneficial to list, on the table, speeds (in kph, or mph, or m/s, or whatever) corresponding to each Mach number at typical temperatures and pressures? -FZ 22:21, 3 Aug 2004 (UTC)
replies: text: I'm for creating a simple, small table of mach numbers at sea level and standard operational temperatures.  If I were a middle or high school kid looking up mach numbers, I'd probably expect to find something like that on this page.  --ABQCat 00:26, 1 Sep 2004 (UTC)

text: Ditto --Teradon 01:19, 27 April 2006 (UTC)
thread_title:  Speeds 

message: I think that the images on this page are terrifically illuminating and valuable, but they are all taken from http://www.kurssit.lut.fi/040301000/main/11_3_2.html.  User:Prkl75 added the images to Wikipedia and this article.  There may be some copyright issues (despite the claim on the image pages), so if anyone happens to have some images that would work for this page in place of those aleady in use, I think that would be good.  --ABQCat 00:50, 1 Sep 2004 (UTC)
replies: text: The main image on the page is captioned "An F/A-18 Hornet breaking sound barrier". The caption implies that we can tell it is travelling supersonically from the visible condensation disc behind it. Other sources on the internet suggest this is an example of condensation from the Prandtl-Glauert singularity, and is not indicative of supersonic flow.JBel 16:11, 31 January 2007 (UTC)
thread_title:  Images 

message: I don't understand. How are sound and the sonic boom effect related? Do sound waves have anything to do with this or are they unrelated?
:This is partially addressed in the article, "When an aircraft exceeds Mach 1 (i.e. the sound barrier) a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as fast moving aircraft travels overhead...".
:I think what could help any discussion here is if you were to ask a specific question which would potentially benefit the article through an explanation here and future inclusion into the article if needed.  I think you may be looking more for an article such as "sonic boom" which has a less technical discussion of the phenomenon (some of which may actually benefit this article, if only to point non-technical readers to a more apropriate article for their inquiries).  --ABQCat 19:54, 2 September 2005 (UTC)
thread_title:  I don't  get it. 

message: Even though I'm Pakistani myself, I do not agree with putting the PAF page here. It does not contain generic information related to the unit of measure, and is a patriotic page. It does not belong here.
:Link removed.
::It was added again. I'll remove it, the link doesn't even work. Keta 21:17, 10 June 2006 (UTC)
thread_title:  Remove the PAF reference 

message: was Czech...not Austrian...
That's not true. Ernst Mach was born in 1838 in a region which at that time belonged to the empire of Austria. Nonregarding the fact that that area NOW is part of the Tchech Republic, Ernst Mach was nevertheless of austrian nationality. He died in Munich, Germany.
Regards from Hamburg, Germany,
Christian  —Preceding unsigned comment added by 195.124.114.36 (talk) 15:05, 12 August 2008 (UTC)
replies: text:  Тhe current state jurisdiction of the city where he was born is not a reason to change his nationality. Its name is not even Czech, but German. And Republic of Czechoslovakia was formed in 1918 following the collapse of the Austro-Hungarian Empire, even after Mach's death (1916).Xunonotyk (talk) 10:09, 9 April 2019 (UTC)
thread_title:  Ernst Mach 

message: In general, the speed of sound depends on the pressure of the medium. This is the main reason why the speed of sound decreases with increasing altitude. Of course, temperature also has an effect on pressure and thereby also affecting slightly the speed of sound. Didi7 12:04, 18 January 2007 (UTC)
replies: text: According to the Speed of sound article you have this backwards. The temperature is the important quantity. "Air pressure has no effect at all in an ideal gas approximation." Spiel496 21:41, 27 January 2007 (UTC)
thread_title:  Speed of Sound depends on Pressure 

message: If actual speed at Mach 1 increases with altitude, why do the numbers in the overview decrease? BQZip01 18:31, 27 February 2007 (UTC)
replies: text: Huh? 'Mach 1 increases with altitude', where does the article say that? Temperature goes down with altitude.WolfKeeper 18:43, 27 February 2007 (UTC)
replies: text: The temperature drops, but the air density does too. As for the reference "So, an aircraft travelling at Mach 1 at sea level (340.3 m/s, 1,225.08 km/h) will experience shock waves in much the same manner as when it is travelling at Mach 1 at 11,000 m (36,000 ft), even though it is travelling at 295 m/s (654.632 MPH, 1,062 km/h, 86% of its speed at sea level)." If this were the case, aircraft would fly lower to fly faster (which makes precious little sense). P.S. please don't take this as criticism, I just am confused. It may be one of those things that is counterintuitive BQZip01 18:54, 27 February 2007 (UTC)
replies: text: Still awaiting an answer on this one BQZip01 14:59, 14 March 2007 (UTC)
replies: text: Mach number is just a number that describes some aspect of the flow around the vehicle. The vehicles in general are trying to minimise drag for the speed that they are travelling at. This in general can be done at an optimum altitude for the current vehicle mass/weight, which varies over the length of the flight. As the vehicle weight goes down, the vehicle's ballistic coefficient is reduced and the vehicle needs to fly higher to maintain the same fuel efficiency over the ground. At low altitude the mach number would be the same or lower as at higher altitude, but the air drag would be much higher as well, so the fuel economy would suffer.WolfKeeper 02:12, 18 March 2007 (UTC)
thread_title: Mach speed decreases with altitude?

message: Is it correct to say "(For comparison: the required speed for low Earth orbit is ca. 7.5 km·s-1 = Ma 25.4 in air at high altitudes)"? Agnamus (talk) 12:25, 1 July 2008 (UTC)
replies: text: Not really. Most, if not all treatments of the speed of sound, mach number, fluid dynamics, etc. are (at least in this article) based on modelling fluids as a continuum - by the time (altitude) you get to low earth orbit, the molecules are so far apart, the Mach number is more or less meaningless. See Knudsen number. I'm not 100% sure about this, but I'm almost certain that it is the case (?) 80.229.172.13 (talk) 17:41, 20 December 2011 (UTC)
thread_title: LEO Mach

message: what is the increment between each mach speed? is Mach 2 twice the speed of sound?  —Preceding unsigned comment added by 86.27.191.227 (talk) 14:39, 23 September 2008 (UTC)
replies: text: If a body is moving at true airspeed V in a gas, and the temperature of the gas in the vicinity of the body is T, then the Mach number of the body is V divided by the speed of sound in the gas at temperature T.  If the body is moving at Mach 2 it is moving at twice the speed of sound; if it is moving at X times the speed of sound it is moving at Mach X.  Apologies for the delay in providing an answer to your question.  Dolphin51 (talk) 10:46, 4 January 2009 (UTC)
thread_title: increment

message: "At Standard Sea Level conditions (corresponding to a temperature of 15 degrees Celsius), the speed of sound is 340.3 m/s (1225 km/h, or 761.2 mph, or 661.5 knots, or 1116 ft/s) in the Earth's atmosphere. The speed represented by Mach 1 is not a constant; for example, it is mostly dependent on temperature Standard Sea Level conditions (corresponding to a temperature of 15 degrees Celsius), the speed of sound is 340.3 m/s (1225 km/h, or 761.2 mph, or 661.5 knots, or 1116 ft/s) in the Earth's atmosphere. The speed represented by Mach 1 is not a constant; for example, it is mostly dependent on temperature." Thnidu (talk) 00:51, 10 July 2015 (UTC)
replies: text: That would be the International Standard Atmosphere. JustinTime55 (talk) 17:35, 12 January 2017 (UTC)
thread_title:  Which standard? 

message: Hello fellow Wikipedians,
I have just added archive links to  on Mach number. Please take a moment to review my edit. If necessary, add  after the link to keep me from modifying it. Alternatively, you can add  to keep me off the page altogether. I made the following changes:
*Added archive http://web.archive.org/web/20110904190008/http://www.aviation.org.uk/pdf/Aircraft_Performance_Flight_Testing.pdf to http://www.aviation.org.uk/pdf/Aircraft_Performance_Flight_Testing.pdf
Cheers.—cyberbot IITalk to my owner:Online 14:42, 13 July 2015 (UTC)
thread_title:  External links modified 

message: "compressibility effects will be small and a simplified incompressible flow equations can be used"
Is it plural or singular?
Aisteco (talk) 20:10, 11 January 2017 (UTC)
replies: text: Plural, unless proven otherwise. Andy Dingley (talk) 21:11, 11 January 2017 (UTC)
thread_title:  Plural or singular?