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How fast does the world's currently fastest passenger plane fly (cruise speed)? Do any passenger planes fly faster than the speed of sound?

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Do you mean fastest EVER, fastest in theory, or actual fastest of a currently flying commercial passenger route? –  Mark Mayo Apr 6 '13 at 21:35
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The concorde was the fastest (supersonic) passenger plane. See also en.wikipedia.org/wiki/Supersonic_aircraft –  knut Apr 6 '13 at 21:36
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@knut I think you'll find the Tu-144 went faster? - "The Tu-144 supersonic transport was the fastest commercial jet plane at Mach 2.35 (1,555 mph, 2,503 km/h). It went into service in 1975, but soon stopped flying. The Mach 2 Concorde aircraft entered service in 1976 and flew for 27 years." - Wiki –  Mark Mayo Apr 6 '13 at 21:39
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I guess I should split it then. I'll do that after I get an answer to this; that way I can build off it. –  DarkLightA Apr 6 '13 at 21:44
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Awesome. I have some answers ready, so await the split eagerly :) –  Mark Mayo Apr 6 '13 at 21:46
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2 Answers

up vote 19 down vote accepted

In history, there have only been two SSTs (Supersonic transports) around for passengers - the TU-144 and the Concorde.

Sadly, neither is available any longer with access to fly on them.

So then we look to the two major manufacturers with almost supersonic capabilities.

Long considered the fastest passenger plane, the Boeing 747 has several variants, each with slightly different speeds. The fastest of them are the 747-400, 747-400ER and 747-8L, all of which can cruise at Mach 0.855ish, and have top speeds of Mach 0.92. So close!

Then we look at Airbus. Their fastest, we're looking at the A380. Its cruising speed is said to be Mach 0.85, while its top speed was shown in a demonstration in 2005 to be Mach 0.96. Even closer!

So with conventional passenger jets, no, we can't go faster than the speed of sound, and Mach 0.96 is the theoretical maximum you'll reach, although it's unlikely you'll be on a flight doing that (they did it with a shallow dive and without passengers/cargo).

Part of the reason for this is design - the entire design of the plane needs to change if one is to break the sound barrier - the pressure and forces exerted on the aircraft would likely see them break apart. Another is the noise pollution - there's a very large sonic boom when the Concorde used to break the barrier.

HOWEVER, you can 'cheat'. If you're in say, a 777 going fast with a massive tail-wind, your effective groundspeed could be faster than it, even though the plane isn't reaching the same pressures. There's a detailed discussion of when this has happened online.

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Your traveling knowledge is truly immense, Mark! Very good answer! –  DarkLightA Apr 6 '13 at 22:02
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Oh I'm waiting for some plane nut to come along and correct me - there's probably some obscure model that I'm not aware of, which would be amusing. Suffice to say though, you won't be breaking the sound barrier in these. –  Mark Mayo Apr 6 '13 at 22:11
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If you build a running track down the length of an A380 and get Usain Bolt to run towards the front at 44.7 km/h (bbc.co.uk/news/technology-19506130) while the A380 flies at Mach 0.96 or 1020 km/h, (a-380.com/about-the-a-380/a-380-specifications) he will be travelling at Mach 1.002! Anyone wanna sponsor this stunt? –  Gnubie Aug 23 '13 at 18:01
    
@MarkMayo you're correct as to there only having been 2 SSTs. There's a supersonic (or maybe they scaled it down to transsonic) business jet in prototype stage, but it's had several crashes already and is nowhere near ready for production. As most countries don't allow supersonic overflight except for military aircraft, such aircraft are of extremely limited use and there's little incentive to design and produce them (the cost are very high, sales numbers would be very low, do the math). –  jwenting Sep 22 '13 at 7:29
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No, there is none and there will be none (until a new supersonic jet comes out). The reason is once supersonic speed is reached the drag resistance of the airplane increases enormously because shock waves are created and maintained. So you need much more fuel for a neglible increase of speed.

< know-it-all-mode on >

Jet fighters with supercruise still have an increase of drag, but first they are modeled to minimize the impact and second they are moving with Mach >1.2 to leave the so-called transsonic regime of Mach 0.8-1.2.

"Transsonic" means that the air around the plane moves in some regions with subsonic speed (slowest under the wings) and in some regions with supersonic speed (highest above the wings). In fact a normal jet has a small shock wave above the wings during the flight.

If every air molecule of the plane moves with supersonic speed, the drag decreases again because the interaction of the sub- and supersonic areas increase the drag.

< know-it-all-mode off >

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i.e. the sound barrier is an actual barrier in airplane design: hard to get through but if you manage it, things get easier. –  Michael Borgwardt Apr 8 '13 at 10:45
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protected by Mark Mayo Sep 21 '13 at 9:01

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