Boeing 787-9 Twin Jet Dreamliner Hits Top Speed of 801 MPH

Discussion in 'HardForum Tech News' started by cageymaru, Feb 19, 2019.

  1. cageymaru

    cageymaru [H]ard as it Gets

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    A Boeing 787-9 twin jet Dreamliner hit 801 mph during a Virgin Atlantic flight from Los Angeles to London. The normal top speed for the plane is 587 mph, but the jet stream was moving at 230 mph over Long Island on Monday. This natural phenomenon assisted the plane to the 801 mph top speed and shaved 48 minutes off the flight time. Pilot Peter James tweeted, "Almost 800 mph now never ever seen this kind of tailwind in my life as a commercial pilot !! (200 mph tailwind )"

    An LAX-JFK Delta flight overnight hit 678 mph at 39,000 feet over the Ohio Valley, while a 737 from Chicago to New York passed 700 mph at 8:43 Eastern this morning. Chicago to New York/Boston routes will be shortened to 1 hour, 24 minutes Wednesday instead of the usual nearly two-hour flight time. Likewise, flight times from Dallas to Boston dipped below three hours, with an Embraer ERJ-190 twin jet achieving 739 mph in the jet streak.
     
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  2. Shadowed

    Shadowed Limp Gawd

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    I've never gone mach 1 before. It wasn't that long ago when mach 1 was considered really fast.

    Pretty cool considering it required a fricking rocket plane dropped from a larger plane to achieve mach 1 at level flight.

    Edit: I agree with others below, this is technically not mach 1. Sorry.
     
    Last edited: Feb 19, 2019
  3. bink

    bink [H]ard|Gawd

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    So what about the return flight??? Look down and see a Cessna 172 below the jet stream passing you??????? HHahHhahah if only
     
  4. KATEKATEKATE

    KATEKATEKATE Limp Gawd

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    my thought as well! suuuucks for the westbound flights. I wonder how much leeway they have with altitude, would flying abnormally high or low allow the flights to avoid some of the headwind or do they just have to deal with the loss in groundspeed?
     
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  5. Jon855

    Jon855 [H]ardForum Junkie

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    There are not lot of people that could say they're breeched Mach 1. However, Mach 1 isnt a fixed speed but had a lot to do with the temperature, air pressure, and other factors.

    Now I wonder did the plane actually breech Mach 1 in the truest sense of the term? I don't think so when taking into account the laminar flows given that there was 200+ mph tailwind coming into factor here. Again, I'm no scientist but I'll be mighty impressed to see a plane cruising at 800mph.

    I wonder what the pilots thought when they saw their airspeed and groundspeed indicators being so far apart.
     
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  6. sfsuphysics

    sfsuphysics I don't get it

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    Yeah not sure how mach speeds measured because with respect to the ground yeah it was faster than sound, but their speed with respect to the medium they were in nope which is why no sonic boom
     
  7. MrDeaf

    MrDeaf Limp Gawd

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    AFIAK, It's not Mach-1, because it is a function of local flow velocity and local speed of sound.

    AFAIK, If it's a 230mph tailwind, that causes sound to travel faster in one direction than the other.

    Were a commercial jetliner actually to hit Mach-1, it would rip itself apart due to pressure buildup.

    Accounting for tailwind, the aircraft was only traveling at 571mph.
    Compared to ground level, it was going 801mph.
     
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  8. DigitalPanhandler

    DigitalPanhandler Limp Gawd

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    mach1 is a very very objective number and term...… it changes based on air pressure and temperature....so.....was it mach 1, or was it just overtly faster then normal?
     
  9. Messy

    Messy Limp Gawd

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    i hear you can reach mach1 if enough people jump in to beat this particular horse to death
     
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  10. Jester1550

    Jester1550 Gawd

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    Didn't break the sound barrier... at least that's what the article says.

     
  11. sfsuphysics

    sfsuphysics I don't get it

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    I'm sure the people on the plane simply don't give a shit, not having the plane rip apart is definitely a bonus but getting to their destination quicker is really appreciated.
     
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  12. N4CR

    N4CR 2[H]4U

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    Nope but ground speed terms perhaps close. TAS definitely not with a tailwind. Plane would break apart going TAS mach 1. Shockwaves would shred the wings as they're wrong shape.
    I've also as a passenger had ground speed over 1100kmh in a 747 in the 90s with a crazy tail wind. Those things are not as sleek or small as a787 lol, it happens sometimes.
     
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  13. Darkswordz

    Darkswordz Gawd

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  14. Ihaveworms

    Ihaveworms [H]ardness Supreme

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    They were not going mach 1.
     
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  15. DiabloRojo

    DiabloRojo Limp Gawd

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    I remember this Twilight Zone episode. Ask the passengers how many dinosaurs they saw!
     
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  16. Jim Kim

    Jim Kim 2[H]4U

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    agreed
     
  17. Nimisys

    Nimisys Likes To Play With Trannies

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    They were at their normal cruise airspeed of Mach 0.85, which is where most airlines cruise at, as well many business jets (though some of those can push 0.90 and FL430)
     
  18. aaronspink

    aaronspink 2[H]4U

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    No, they'll just use vastly different routing. The fact that they were even so far south was because of the tail wind. The GC route would of put them over the northern part of the Hudson Bay/Labrador sea in northern Canada. The routing that they took was at least 500 miles LONGER than the GC routing just to get that insane tailwind.
     
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  19. aaronspink

    aaronspink 2[H]4U

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    No, it didn't breech Mach 1 in any sense. The 787 can't structurally go much beyond Mach .9 without significant issue. A 787 at Mach .95+ is basically uncontrollable and will stall.
     
  20. aaronspink

    aaronspink 2[H]4U

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    Actually, a 747 has a higher Mmo than a 787 (.92 vs .89). The 747 wings have more sweep and the upper deck ends up being an aerodynamic aid at high speed as well. In fact, of commercial airliners, the 747-400 has the highest Mmo of all planes except the Concord and TU-144, both supersonic airliners.
     
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  21. daglesj

    daglesj [H]ardness Supreme

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    On a flight back from Chicago to London we hit 650MPH with a tailwind. I thought that was pretty fast.
     
  22. Krizby

    Krizby n00b

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    well B787-9 pilot here, B787-9 maximum Mach number is .9, same as B747-8. The new generation B777X is gonna be M .95. The maximum mach number depends on the wing design, as you know the air above the wing is accelerated to lower the pressure above the wing creating lift; however once the air above wing reaching the speed of sound the pressure above the wing inversely increase causing high speed stall. Btw I have seen wind speed > 200kt (nautical mile per hour) couple of time, always during winter time that we have such strong winds; during summer the winds are slower but there are a whole bunch of Cumulonimbus clouds.

    Ps: Speed of sound depends on temperature mostly, B787 mostly cruising at M .85 (at around 570 mph gound speed), with 230 mph tail wind we are flying at 800 mph.
     
    Last edited: Feb 20, 2019
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  23. TheOne&OnlyZeke

    TheOne&OnlyZeke 100% Irish

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    Pretty cool. 48 minutes early landing time
    Lucky the plane itself wasn't breaking the sound barrier. it would have fallen apart I'd say

    Thats some tailwind though.

    For pilots out there, would the jet be harder to control when you end up with that kind of tailwind?
     
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  24. Krizby

    Krizby n00b

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    Nah we usually don't control the aircraft manually once it is airborne, though manual control is also the same as the flight computers will take in pilots input and give command to flight control surfaces in accordance with the speed of the aircraft. Tail winds is only problematic when we are taking off or landing, usually the limit is 15kt of tail wind for T/O and Landing.
     
  25. c3k

    c3k 2[H]4U

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    What was he doing tweeting?
     
  26. M76

    M76 [H]ardForum Junkie

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    So if you get 50mph tailwind on the drag strip and therefore your car does 120 instead of 110 at the line then you were not doing 120?

    There is a reason we use the terms "ground speed" / "air speed"
     
  27. focbde

    focbde Gawd

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    Not quite as good but had a decent tailwind once too...

    20181017_185915.jpg 20181017_185920.jpg
     
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  28. Cardio

    Cardio Limp Gawd

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    If you were running 10 MPH on a treadmill located in the back of a truck traveling 70 MPH would you think you were running 80 MPH, 70 MPH or 10 MPH. Ground speed and the speed you are traveling have not much to do with each other except how long it will take to get to your destination. Warp a little space and we might have to alter that a bit.
     
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  29. Olle P

    Olle P Limp Gawd

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    That's not a 100% certainty... A DC8 has supposedly gone supersonic once in a test flight and survived.
    Not recommended though, because the transsonic a can really cause havoc.
     
  30. Burticus

    Burticus 2[H]4U

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    With my luck, we would have had to sit on the runway 2 hours after landing for "reasons". With no AC.
     
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  31. Krizby

    Krizby n00b

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    Well any commercial aircraft will experience high speed stall way before reaching Mach 1 though, that means the aircraft lose all lift and falling like a rock, you will be dropping at 125mph towards ground, so yeah don't ask commercial pilots to fly at Mach 1 :). Concorde however fly at Mach 2, just hope they resume in business.
     
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  32. zauber

    zauber n00b

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    En route controller in NY here. 767 pilot reported a 204 knot head wind at FL360 (36000 feet) last week. Can't recall a report higher than that, 30 years experience. Many flights filing initial cruise altitudes in the low 20's, until they get out from under the jetstream farther west or south.
     
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  33. Verge

    Verge [H]ardness Supreme

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    My last flight to vegas took forever, we had groundspeed at cruise of 310kts according to flight aware :(

    effin headwinds
     
  34. odditory

    odditory [H]ardness Supreme

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    Username checks out.
     
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  35. toddw

    toddw [H]ard|Gawd

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    What if the treadmill was on the plane, but the observer was in a submarine, would it be mach 1 underwater? :ROFLMAO:;)
     
  36. focbde

    focbde Gawd

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    Well, technically with a reduction of speed and thus removing the flow separation problem you'll gain lift again, so you won't drop like a rock... power back - drag will slow you even in a nose-down attitude and lift will resume once closer to critical Mach. Unlike in a low-speed stall scenario, there's plenty of flow over control surfaces to be able to change the attitude of the plane.
     
  37. 1Nocturnal101

    1Nocturnal101 Gawd

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    The FAA limits how fast a commercial jet can go with passengers on board as there are safely guidelines and of course impact on other jets flying in succession on the same flight path.
     
  38. Krizby

    Krizby n00b

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    Problem is it's not the flow separation that cause the high speed stall, it is the shockwave caused by supersonic airflow above wings. For low-speed stall we pitch down to reduce the angle of attack (angle between the aircraft pitch and the flight path) and increase airspeed to regain lift but for high speed stall the only option is to use speed brake to reduce airspeed as pitching down will worsen the stall. It's best to recognize the stall early and make recovery actions because once you are in a deep stall with a descend rate over 10 000ft/ min, chances of recovery is pretty slim.
     
  39. Derfnofred

    Derfnofred Gawd

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    1.) Cool for those of us not in this world. (Really!)
    2.) For anyone else not sure what Mmo means in this context, it's Maximum Mach Operating. :)
     
  40. KD5ZXG

    KD5ZXG Limp Gawd

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    What happens when they unexpectedly leave the stream going higher than Mach1 in a plane not designed for that?