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  • screaming_emu
    replied
    Well, when the spoilers deploy, they separate the airflow over top of the wing which does lead to turbulent airflow behind the spoiler. This isn't a picture of the airflow behind a spoiler, but the airflow overtop of the wing is separating due to the wing being at too high an angle of attack (stalling), but none the less you can see how the airflow becomes turbulent.



    In light aircraft (and probably big ones too) this turbulent airflow will hit the horizontal stabilizer and cause a bit of a turbulent feel. Actually, if you slow down to a really slow airspeed in a light aircraft, and look backwards, usually you can see the horizontal stab bouncing around quite violently. I'm not familiar with flying large aircraft yet, so I dont know if the turbulence you feel when the spoilers are deployed are from the turbulent air acting on the wing, or if it is in fact the turbulent air bouncing the horizontal stab around.

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  • MaxPower
    replied
    ^^I recall being onboard on a LH321. We've just landed and not even a whole minute passed by this captain made a rapid right turn, so rapid that the seatbelt was tighten much on my stomach. It was very shaky..! How much does a A321 need down the runway before he is able to make the rapid get-away turn from the runway ???

    Oh and btw. Spoilers were deployed IIRC ..

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  • ACman
    replied
    Originally posted by pkonowrocki
    Yeah, but when you use spoilers in the air to reduce speed, do they casue some kind of turbulence ? I was flying on A320 and pilot used spoilers on descend and except for the noise it was shaky. I would like to know if it was caused by spoilers or just the wind.
    Spoilers will do that on aircraft, it gets pretty shifty.

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  • Guest's Avatar
    Guest replied
    Yeah, but when you use spoilers in the air to reduce speed, do they casue some kind of turbulence ? I was flying on A320 and pilot used spoilers on descend and except for the noise it was shaky. I would like to know if it was caused by spoilers or just the wind.

    Leave a comment:


  • screaming_emu
    replied
    Originally posted by pkonowrocki
    Actually do the spoilers reduce the speed ?? I thought it helps the aircraft stay on the runway and not "jump" just after touchdown.
    Oh and btw. 767s also can stop really fast. When I was flying to Warsaw captain set autobrakes to 3 and with reversers it stopped reallly fast. When flying something smaller, like 737, do you have to use spoilers ?
    They do reduce the speed as well as dumping the lift as you said. Whenever you stick something up into the airstream it creates drag, especially when they're as big as spoilers are. Also, a combination of dumping the lift created by the wings, there's also a bit of downforce created, this pushes the airplane harder down onto the wheels so the wheel brakes are more effective.

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  • Guest's Avatar
    Guest replied
    Actually do the spoilers reduce the speed ?? I thought it helps the aircraft stay on the runway and not "jump" just after touchdown.
    Oh and btw. 767s also can stop really fast. When I was flying to Warsaw captain set autobrakes to 3 and with reversers it stopped reallly fast. When flying something smaller, like 737, do you have to use spoilers ?

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  • Kevin
    replied
    I remember when i was in Sydney earlier this year I saw a Dash 8 touching down right on the piano key, just to vacate teh runway as quickly as possible to get to the gate (runway 16R).

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  • G-DALE
    replied
    Originally posted by Colin Parker
    It would be as ridiculous as landing halfway down the runway on purpose because you merely want to vacate at the end!
    Okay, in a B747 or similar I agree, not so bad in something like a Dash 8 or an F50 though.

    Dale

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  • jmackey_YYT
    replied
    Would strong headwinds and the combination of needing to get to the opposite end of the runway to exit have any impact on the decision to do this?
    ________
    WENDIE 99

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  • screaming_emu
    replied
    Originally posted by Colin Parker
    In CX we always land in the 1000-2000ft touchdown zone. Anything outside this will earn you a fail on a flight test.
    or worse

    [photoid=519106]

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  • Colin Parker
    replied
    CX definately requires speedbrakes to be used for every landing. Not only does it act as an aerodynamic block to airflow, but it pushes the weight of the aircraft down onto the breakes and wheels which helps it to stop. We most certainly do not disarm the speedbrakes even if we can roll the end end of the runway. It would be as ridiculous as landing halfway down the runway on purpose because you merely want to vacate at the end! In CX we always land in the 1000-2000ft touchdown zone. Anything outside this will earn you a fail on a flight test.

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  • AJ
    replied
    Originally posted by G-DALE
    Ah, that explains it then.

    If the aircraft's gate is towards the end of the runway then there's not much point in vacating early, so they'll often keep it rolling to the last taxiway, thus there's not as much of a hurry in stopping.

    Alternatively you can touchdown towards the middle of the runway, then apply spoilers and reversers etc.

    Cheers,

    Dale
    Mr. Boeing would have a hernia! Roll throughs still require the speedbrake to be armed and idle reverse selected (selecting idle reverse will deploy the speedbrake even if it was not armed. The only thing that will not allow the spoiler to be deployed is if the thrust was never retarded to idle. 3,800m would not be long enough in that situation.

    Most airline SOPS dictate a touchdown in the touchdown zone (prior to 2,500' in a -400). Even our Dash 8s are required to do that since the installation of QARs.

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  • MaxPower
    replied
    Originally posted by G-DALE
    Yes.... With spoilers and reversers deployed
    How about without them reversers and spoilers, how much of a 3800m runway will it have to use before it is at deadstop ? Just curious if you happened to kow that as well.


    Thanks

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  • G-DALE
    replied
    Originally posted by YYZPICS
    747's can stop pretty fast..
    Yes.... With spoilers and reversers deployed

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  • YYZPICS
    replied
    747's can stop pretty fast..

    A normal arrival on 33L

    [photoid=5682767]

    A 774 half way down the rwy(33L)

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