What is the fastest Civil Airliner flying today??

[TacitBlue]

oh, interesting.

[Rocket_Bird]

[quote]Anybody know the ultimate load factor on the 744?
7 g's sounds ridiculously much, but then again I'm not an engineer

[Nexus]

Limit load factor is that extra buffet.

Ultimate load factor is when the aircraft's wings and fuselage will start to deformate, and I talk about permanent deformations  ;D

[Craig.]

the plane wasnt a write off, it flew after the incident.

[Saratoga]

Which is why the picture is there. Ya the SP is much much shorter than the rest of them, especially the -400.

But on the topic, the 747 is currently the fastest airliner flying. It can do Mach .85 (trying to use Mach as a reference since it is stable). The fastest production non-military use plane I know of us the Citation X, Mach .92 cruise.

In addition to what Nexus said, the fact that also prevents the 747 from cruising supersonically is the huge drag incurred between Mach .96 or so and Mach 1.4. Even the most aerodynamic airplanes such as the Concorde need afterburners to get through this region. Some military airplanes, the F-22 comes to mind, are capable of supercruise, cruising supersonically without using afterburners, but take a look at the F-22. Not exactly a 747 in any shape, form, or fashion.

[Mobius]

The engines on aircraft like that aren't designed to exceed mach 1 either.  Jets engines don't work with supersonic airflow so it would be impossible to cruise at or above mach 1.  Drag also increases dramatically as an airplane approaches mach 1 so it wouldn't be very economical either.  I think, please correct me if I am wrong on this, many of you seem more educated on the subject matter than I am.  :)

[Nexus]

Now tell me, what kind of engines does the Concorde have?
It sure aint pistons, it was turbojets  :)

[Craig.]

the big differance being the way the airflow was directed into the engine. The air at and near supersonic speeds, needs to be directed into the engines or else they wont get enough air or too much, can never remember which.

[Saratoga]

That's why they were mounted flush with the bottom of the wing, so the air would naturally enter the engines, and why they had the doors at the front of the engine to control the amount of air entering it.

Turbojets are perfectly capable of exceeding Mach 1, it just seems hard due to the high amounts of drag. A 747 was never intended to go this fast, hence the huge amounts of frontal area. The extremely sharp-nosed Concorde even has trouble getting up in speeds and it is exceedingly good at aerodynamic efficiency, it's just really hard to get a plane to go that fast. Military airplanes are capable of fast speeds even with bombs and what not by pure horsepower, larger airliners, to save fuel and cost less, have to actually be semi-aerodynamic. But a turbojet is perfectly happy at supersonic speeds.

[SilverFox441]

It's actually correct to say that a turbojet cannot exceed M1...at least the incoming airflow can't exceed that speed. The most common method of slowing the incoming airflow is to use compression control in the upstream airflow.

[Saratoga]

oh no a pure turbojet cannot, it would stall with the supersonic air. I didn't even stop to think about that, eh either way. Anyone know how the Concorde pulls it off?

[Mobius]

Fighters and the Concorde and others uses moving panels and ramps in the intakes.  As an airplane goes through mach 1, a shockwave is formed off the leading edge of wings, horizontal stabilizers, etc.  The shock waves are also what cause a sonic boom.  The air infront of these shockwaves is moving at supersonic speeds while the air behind it is moving at subsonic speeds.  The panels and ramps in the inlets create shockwaves which slow the incoming air down to subsonic speeds so the engine can function properly.  As an airplane moves faster and faster, the angle between the wing and the shockwave decreases, so at higher speeds the air moving into the engine would eventually be mostly supersonic again so conventional jet engines have a built-in "speed limit" around Mach 3.5 or so (I think, don't quote me on that), which is why the NASA and other organizations are developing Ramjets and Scramjets.

Fighters and high speed airplanes use elliptical wings instead of wings shaped like an airfoil so they created lift with AOA mostly instead of a pressure difference.  I am not sure about this part though, so don't believe me completely .  I also don't think it makes a difference whether the air is moving supersonic or subsonic in creating lift between airfoils and elliptical wings, although I really am not sure.

Again, correct me if I am wrong, I am not completely sure on all of this...

[TacitBlue]

That would probably explain why the XB-70 toped out at mach 3.something. That really is an amazing aircraft by the way, if you havnt been to Wright Patterson (USAF museum), you should go and see it.

[Ivan]

i think the fastest Airliner (not actually a civil one) is Air Force One, A 747-200 with the engines of the 747-400. is said to have a M.9 cruise speed

[Ivan]

The panels and ramps in the inlets create shockwaves which slow the incoming air down to subsonic speeds so the engine can function properly.

Prevents overspeeding the fan...

so conventional jet engines have a built-in "speed limit" around Mach 3.5 or so (I think, don't quote me on that), which is why the NASA and other organizations are developing Ramjets and Scramjets.

A conventional jet engine whitout intake ramps (MiG-25 recce version) will survive a one-way trip to M 3.2. Consider the engines scrap metal after that.