Massive jetstream!!!

[renormalised]

I was just having a look at Singapore airlines flight SIA211 at flightradar24.com and at one stage the plane was moving at a speed of 771mph at 38000 feet. 771mph!!!!!!:eyepop::eyepop:. Ground speed, though. The plane is Boeing777 and their rated max cruise speed is 590mph. Must be a hell of a tail wind at that height. A Qantas flight, QFA32, from Heathrow, was doing 750mph at 39000.

[kinetic]

FR24 is possibly reporting ground speed, Carl,:shrug:

The airmass might be at a few hundred kms/hr but it's groundspeed would be that figure

Here is the JS map for Oz today, note the reds and oranges.
http://en.wikipedia.org/wiki/Ground_speed

Steve

[renormalised]

It was doing 672kt airspeed (or thereabouts), which is 771mph. I was looking at a 180mph jetstream. The position of the core of the jetstream would be in accordance of where the plane was coming in from.

I'm very well aware of the differences in speeds and what they are, Steve. I'm an aircraft fanatic and I've flown often enough:)

[kinetic]

<facepalm> well....for the benefit of others reading then Carl ;)

[renormalised]

No worries:)

[Peter Ward]

The strongest jet streams I have experienced to date have been near Japan...around 240 knots,and I'll let you do the math.

That said, airspeed in all heavy jets in cruise is around Mach 0.79 to 0.86, so unless you were in a Concorde, the sound barrier was never even close To being busted. ;)

[Zaps]

What Peter Ward said.

An airframe section must be carefully designed and constructed to meet critical specific criteria before it is even capable of achieving and sustaining supersonic flight. In other words, atmospheric vehicles not designed to be supersonic cannot - and won't - become supersonic without very quickly falling apart.

[gbeal]

Yeah, wot P Ward sez. My bird tops out at a measly 155kts, LOL.
Gary

[DavidTrap]

So Peter, if you were in a jet stream at 240knots doing ~490knots at cruise in a 747 wouldn't your ground speed be greater than the speed of sound?

DT

[renormalised]

Well that's what I was thinking...the speeds were unrealistic for heavies. It's probable that the reported speeds were glitches with the instrumentation that were recording them. However, if you're belting along at 400-500kts and you have a 150-250kt tailwind, your groundspeed is going to be pretty fast. So's the airspeed.

Here's one, now...a Qantas jet, flight QF582 at 39000 feet doing 648kts. He'd have to have the mother of all tailwinds to do that and I'm just wondering how a 20-25 year old 747-438 would handle that structurally. Not too well I'd imagine.

But nearly every plane I've seen flying at 37000-40000 feet today from west to east has been traveling at those high speeds.

660kt at 35000 is the speed of sound, or 760mph groundspeed.

I'd like to find out off the captains of these planes what they were really doing. That'd be the way to verify the speed of the planes.

[renormalised]

That's a given....that's why I was flumoxed and wondering about these speeds...it'd have to be groundspeed and certainly not airspeed.

[middy]

Interesting. I never gave it much thought at the time, but yesterday evening I was on a flight from Melbourne to Brisbane. There were gale force winds in Victoria and we must have had quite a tailwind because for a while the flight track screen was showing us travelling at 1016 km/h (Altitude = 12,000 m).

Later in the flight we had a bit of turbulence as the Captain said we were coming out of the high speed winds and the speed some time later had dropped to about 880 km/h, which I believe is about the cruising speed for a B737.

[Peter Ward]

It's really easy to think of it this way: boat going up stream goes say, 20 knots relative to the bank. Downstream it gets up to a 40 knot clip. Is the boat going any faster? No it's still doing it's 30 knot speed, the river simply makes the relative speed ( to the bank or ground ) seem faster or slower.

[Peter Ward]

A little known fact is heavy jets have enough sea level thrust to make orbit. The sad fact is they can't sustain that thrust at 35,000 feet.....hence no Sydney to London in 40 minutes yet......

[renormalised]

I should think so....326000lbs of thrust at sea level (that's all 4 engines) for an A380-861 and 320000lbs for the A380-842 (which Qantas flies). Not bad...that much thrust could easily lift a relatively large rocket into space, but jets don't cut the mustard.

[Peter Ward]

Don't believe what you may read in the media ;)

The last edition of my FCOM (sorry: Flight Crew Operating Manual) says QF trent 900's to be flat rated to 72,000 pounds of thrust.. ie. total of 288K...
..not quite sure where that 320K figure came from....

...anyway they are air breathing engines, that, unlike rockets, literally run out of puff at altitude.

[renormalised]

I was looking at the rated thrust for the Trent 972B engine (80,231lbs). The other engine was a GP7270 (81,500lbs). They were for maximum thrust. It did say that the GP7270 was normally rated at 70,000lbs for the A380. So I imagine the Trents would be rated likewise.

Yep....they need methane/LOX fuel like the Aurora spyplane:) That'll give them some more puff:)

Melt the engines in the process!!!:):P

[pgc hunter]

Looking at Flightradar24, eastbound jets are doing in-excess of 1200km/h ground speed at cruising altitude of 30-40000ft all across Vic and NSW. Yesrterday, I was viewing the Boeing 747-400 of QF 64 from Johannesberg to Sydney doing about 1,240km/h above Adelaide and Mildura/ NW Victoria and SW NSW... that is well over Mach 1 at SEA LEVEL, let alone at FL 390 where the jet was crusing. IN zero wind, Mach 1 at 35,000ft equals about 1,058km.h. This aircraft was travelling inexcess of Mach 1.15 ground speed at cruising altitude, fast enough for a sonic boom to reach the ground, but thanks to the tailwinds, the airflow over the wings was no more than 900km/h, fooling the aircraft into an airspeed of 900km/h, yet doing in excess of 1200kmh groundspeed....but because the wings were doing 900km/h relative to the windspeed, there was no sonic boom to be heard.

Assuming perfectly still conditions at the same altitudes...Mach 1 (the "sound barrier" threshold) equals 1078km/h at 33,000ft, or 1220 km/h at sea level.

The typical groundspeed of commercial jets is around mach 0.85, or about 900km/h.

The jetstream is so strong, that east-bound commercial airliners are literally travelling at supersonic ground-speed. In still conditions aloft, 1200km/h would equal Mach 1.12.

[renormalised]

Shows you how much thrust the engines (PW F135-100) for a F35 generate, in such a small package. Only 1.7t in weight and yet they generate 43000lbs of thrust!!!.

[Peter Ward]

Guys...I think a major point is being lost here... "groundspeed" is a little irrelevant.....you will not produce a sonic boom doing M0.86 in a jetstream adding another M0.15 to your progress over terra firma....your speed through the air is still "just" M0.86.

Sure, some ground-speeds can get up to quite a clip (or just the opposite if you happen to be flying the opposite direction), but the airspeed (ie speed through the airmass) is the same...hence no sonic boom even if your ground speed is Mach 1.01

[pgc hunter]

The F-22 is no dog either...... I was parked at the north end of RWY 17 at Avalon Airport on their arrival for the airshow when they slammed their twin Pratt & Whitney F119 PW100 engines in full afterburner..... the rest is friggin history......only the B-1 with their 4x GE F101 afterbrurning turbofans came close....... and the FA/18F Superhornet with their twin F414's... WOW just put everything else to bed including the F-16's and F/18's...

[renormalised]

Right now, there's a China Southern Airways B777 (flight CZ302) at 36000, doing 844mph (1358kmh) ground speed. He's probably only doing 550kts airspeed.

[renormalised]

The PW F119 engines only generate about 32000lbs, but with two of them, it makes up for the substantially less thrust. Imagine two F135's in a fighter plane. They've tested the F135 up to 50000lbs.

[kinetic]

Pete, I think I covered it in post 2...but he did say he was well aware :)

Steve

[renormalised]

Quite correct.

[koputai]

If you're in the coastal areas of Sydney, just look up and watch the domestic flights that overfly Sydney at 35,000 - 38,000 ft going North to South. If you line them up with a straight edge at this time of year, you'll see they are pointing in a significantly different direction to that which they are travelling.

My wife went out on the new Qantas Sydney to Dallas flight the other day, which got there in a stupidly short period of time, but on the way back it's often doubtful the plane will make it without having an unscheduled stop for fuel enroute, and that's with the plane only 2/3rds loaded. Luckily she's coming back out of Buenos Aires, a more direct headwind, but a shorter flight.

Cheers,
Jason.

[AstralTraveller]

You think those planes are moving?? You should see some of the east-bound bicycles around there. Ground speeds above Break 1 - probably Break several if you come off! :eyepop: :lol::lol:

[renormalised]

Any sonic booms...or do they just have their iPods turned right up:):P

[von Tom]

I have been working the last couple of days. One of the sectors I was on starts at 45nm Sydney out to 200nm. I sequence the internationals inbound and separate with the outbounds. The westerly wind was phenomenal and made our job quite difficult in judging our vectors for sequencing, particularly when there's a drop off of 80kt headwind descending through 22,000ft. One jet experience severe turbulence inbound.

The highest groundspeed I saw was 670kt westbound at 39,000ft on a B777. The slowest inbound was 180kts groundspeed on an A330 at about 22,000ft. One A330 was holding at 29,000ft doing 560kts groundspeed on the outbound leg of it's hold. I had to turn it immediately back so it didn't lose its slot. One inbound 767 reported 195kts on the nose. Quite a busy couple of days. Back tomorrow at 5am!

Tom

[DavidU]

Tom, that must be a nail biting job you have there.

[Gem]

Perth to Sydney used to be 30 to 45 minutes faster than Sydney to Perth on nearly every flight. I haven't done that leg in a while now.

[midnight]

We went back to Syd very recently and the 747 we were on took about 3hr20min. Coming back on the Monday took 4hr 30min. Easily watched 2 movies coming back.

On one trip over east last year, the Qantas pilot flew down to Melbourne from Syd before turning west to Perth.

Quite fascinating when you think about it.

Really enjoyed the 747 on the flight over. I said to my wife (who hasn't been on one yet) watch the outboard engine as we flew over the Perth hills just after takeoff - moving around like stiff jelly! She quickly shut the blind :lol:

Darrin...

[FlashDrive]

As an ex Aircraft Engineer in the RAAF at Amberley ( F111C Squadron ) ..... How these planes can sustain these speeds ( engine rpm ) is difficult ... because at the speed of sound ... air becomes to " thin " and unstable at the intake of a jet engine ( shock wave is formed ) .... the F111 Aircraft has a " canard " that moves into the direction of the airstream causing it ( the air ) to slow down allowing a greater " volume " of air to enter the engine intake .... thus preventing " flame out " or commonly known as " compressor stall "

At 20,000 feet (6,096 meters), the speed of sound is 660 miles per hour (1,062 kilometers per hour).

So these planes could certainly make " excellent " fuel economy from such a tail wind .....infact some Airline Companies give their Pilots a " bonus " because of the fuel savings .

What a " ride " ... just stick your head out the window ..... :P

Flash :D