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lets play a game: who can explain this?

Discussion in 'The Lounge' started by colbystephens, Oct 18, 2006.

  1. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    ok, pilots are not allowed to play. everyone else is fair game...

    explain the emboldened statement:

    A jet plane taking off from an aircraft carrier is propelled by its powerful engines while being thrown forward by a catapult mechanism installed in the carrier deck. The resulting high acceleration allows the plane to reach takeoff speed in a short distance on the deck. However, that high acceleration also compels the pilot to angle the plane sharply nose-down as it leaves the deck. Pilots are trained to ignore this compulsion, but occasionally a plane is flown straight into the ocean.

    i'll post up in a few hours w/ the answer if no one gets it.
     
  2. SkysTheLimit

    SkysTheLimit 1/2 ton status

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    Well, being that the craft is dragged by its nose gear, the resulting force would cause the rear to squat, leaving the craft with an upward pointing pitch. I would surmise the pilot would attempt to correct for the squat upon leaving the deck for fear of wanging the ship with his tail.

    If it's right, I meant it, if it's wrong, I'm a mean boulderdash player... :haha:
     
  3. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    you're not right, but you've got some good thoughts which play into the answer...
     
  4. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    In the old days (and even w/ some large/heavy planes today), when
    they leave the deck, they "sink" below the level of the flight deck, but not
    nose first.

    I'd say that use of the word "occasionally" is probably a bit strong.
    Perhaps it's happened a handful of times, but I'm sure that either a) the
    avionics computers are controlling the attitude of the plane after launch,
    or 2) the pilots are trained to put back-pressure on the stick which is the
    same control input used to take off under conventional (land-launched)
    conditions.

    No, I'm not a pilot, but I know several.:)
     
  5. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i'm not sure if that's an answer or not, but it's not right in respect to the question at hand. :)
     
  6. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    I guess I was just questioning the basis of the statment. :) Because I've been on carriers, and I've never seen a plane take off nose down. The whole plane kinda hunkers down immediatly before take off, but not nose down.
    And ,well, I cheated :), I asked a friend of mine who was a Navy Pilot in the late 90's. He'd never heard of this Phonomenon.
    Is this modern day stuff your speaking of?
     
  7. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i don't know how modern it is - it's published in my physics text book which was new a year ago. this is dependent on how much influence the pilot has over the direction of the plane at take off (i don't have a clue how often an autopilot type system would be used in this context.) i think this is EXTREMELY rare, as, like the text says, pilots are trained to avoid putting the plane in the ocean.
     
  8. SkysTheLimit

    SkysTheLimit 1/2 ton status

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    I do know that newer aircraft are "hands-off" launches and the flight computer handles putting the plane in the air. I'd be curious to see what your book says about it.
     
  9. sarasotausmc

    sarasotausmc 1/2 ton status GMOTM Winner

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    The reulting G's throw the pilot's head to the rear, subconciously making him think he is looking/heading upward, therefore overcorrecting for something that is not actually happening?

    Just a SWAG.
     
  10. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    this is very close!
     
  11. wasted wages

    wasted wages 3/4 ton status

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    G-force pushes his eyes back into his head skewing his visual perception.

    Kinda like top fuel and funny car drivers,,,vision gets blurred first 60 ft from g-force..
     
  12. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    close. i'll post up the answer after my next class. (2 hrs from now)
     
  13. tiger9297

    tiger9297 1/2 ton status

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    I am a commercial pilot. I have no idea. I have never taken off from an aircraft carrier. :D
     
  14. surpip

    surpip 1 ton status

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    i dont see how this is possible, the g forves would cause the hands to come back, the left (on the throttle) would come back and kill the engines, this has happened before, but there is a solid grab handle forward of the throttle to prevent this.
    I the pilot pulled back on the stick on take off, he would climb, but pull back to far, and plane stalls and you are in the drink.
    the pilots are trained to climb, and make a slight clearance turn(left or right depending on the cat. they took off on) but untill there is weight off wheels, the do not touch the stick.

    i worked on the flight deck for about a year
     
  15. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    by the way, i totally forgot to mention that this scenario is pretty much dependent on it being night.

    ok, well, according to my physics book here's what happens:

    clearly there is a downward force on the pilots body as a result of gravity. there are little hairs in some fluid in your ears which sense the direction in which these hairs are hanging and tellthe brain which direction is downward. under normal circumstances (such as accleration of a car) these hairs are forced backward by the acceleration, but the stimula of the eyes makes a correction for this movement of the hairs, so the brain does not think that the body is tilting backward. however, if at night on an aircraft carrier, there is little by which the eye can judge the speed. now, i don't have my book handy, so these numbers are guesstimates as i'm hoping to recall them correctly, but essentially if you are accelerated at 85 m/s^2, then your little hairy friends make your brain think that you are tilting back at a 76* angle, which is incredibly steep. since there is no visual stimuli to let the pilot note that what he's feeling isn't accurate, the pilot feels like he's tipping back like this, and attempts to correct and keep the plane straight by nosing down into the ocean.
    :D neato.
     
  16. 4xcrazy

    4xcrazy 3/4 ton status

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    I knew that,,,,,

































































    :p: :D :wink1: :crazy:
     
  17. GotLabs

    GotLabs 1/2 ton status GMOTM Winner

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    I missed this one,

    Its like the spinning chair in avphys, R ear on L knee, eyes closed, spin for a minute or so tell the person to sit up fast and open their eyes. Does crazy things to the mind. The fluid moves so fast, it causes the brain think in reverse.

    Thats were instruments come into play.

    I am not a pilot, nor do I want to be one:D .
     
  18. tiger9297

    tiger9297 1/2 ton status

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    That's interesting. Like I said I have never taken off from an aircraft carrier, but I have experienced vertigo while in the clouds (instrument flight). You will swear the plane is say, in a dive turning to the right, while you are actually flying "straight and level". Many people have been killed b/c they corrected when no correction was needed ie. SEE JFK, Jr. In my honest opinion it is not safe to fly in extreme instrument conditions w/out Autopilot. Good post. Interesting.
     
  19. chevyfumes

    chevyfumes Court jester

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    Watch for the muzzleflash!
    You never said what direction to spin but Jr. just did it and he sat up sayin "don't shoot cookaracha"...Must have worked...:haha: :haha: :haha:
     
  20. ARAMP1

    ARAMP1 Aviator Extraordinaire

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    (Disclaimer: This is coming from an Air Force pilot, who has done zero actual carrier take offs or landings, and only a handful in the sim. However in the last ten years, the Air Force and Navy are sending more and more undergraduate pilot trainees to the other branches pilot training courses. Today, I’d say maybe one in 4 or 5 have a chance of attending the other branch’s pilot training, so I can safely presume that the training we receive is fairly similar.)


    Okay, back to the thread at hand. Very interesting, however I believe it is somewhat inaccurate. Take off and landing (along with air refueling and a few other things) are what we refer to as “critical phases of flight”. During these times, you have strict airspeeds and configurations to fly. For instance, when a military aircraft takes off, we have done TOLD (take off and landing data). We have a strict air speed and attitude of what the aircraft should be during these times. We know (with how much gas we have onboard and what the winds are) that when we take off and we are in full military power that you know the pitch that we must fly to hold your climb out air speed. On takeoff, you are looking 75% inside at the ADI (artificial horizon),HSI(compass),altimeter, VVI, etc. and not out the canopy, especially at night with no outside references. That being said, I don't know how one could pitch down, or even sink (ha, that was funny, sink as an unwanted descent in altutude and sink as in not float) on takeoff.

    Anyway, that's just my thoughts, but I agree with th physics of it and how it reacts in your inner ear. I have been spatially D’ed so bad before that I was seriously fighting my body to fly what my instruments told me. And, the more G's you're pulling, the harder the fight is.
     
    Last edited: Oct 20, 2006

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