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Bad physics in Casino Royale?

  1. Nov 18, 2006 #1
    I was watching "Casino Royale" with my friends yesterday, and there was a part where a commercial plane was about to land, but it seems that its runway was being obstructed, so it suddenly took off again.

    I am under the impression that it's not possible for a commercial airplane to takeoff when it is landing. I understand that in order for a plane to takeoff, its thrust must sufficiently large enough so that the lift force overcomes the weight. Since the commercial aircraft is so heavy, wouldn't it require a huge amount of thrust change? If this thrust change takes place in such a short time (the plane barely make contact with the ground before it takes off in the movie), wouldn't the passenger feel too much jerk and pass out or something?

    Thanks in advance for your help.
     
  2. jcsd
  3. Nov 18, 2006 #2

    FredGarvin

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    I haven't seen the scene you are discussing. However, I will say that it's not impossible. Not likely either, but not impossible. There are a lot of factors that play into it. I could see it happening if the landing speed were higher than normal. I think you would be surprised by what large airliners can really do. We are used to seeing them flown a certain way because that is the safest way. Heck, no one thought a 707 could do a barrell roll.
     
  4. Nov 18, 2006 #3

    russ_watters

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    A plane that is landing is constrained by drag - the plane is flying slow, the flaps and gear are down, and the angle of attack is high, so the engine thrust is relatively high without increasing the speed. Because of that, it is tough for a landing airliner to make a dramatic take-off-like climbout right before touchdown. It basically has to stay level for a while, gain speed slowly, raise the flaps and gear, then pull up. It probably isn't any easier to return to flight that way than to do an acutal touch-and-go.

    But I haven't seen the movie either...
     
  5. Nov 19, 2006 #4

    arildno

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    Good heavens.
    You're talking James Bond here, right?
    007 is beyond physics; if you can't relate to that, have a martini, shaken, not stirred.
     
  6. Nov 19, 2006 #5

    arildno

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    Good heavens.
    You're talking James Bond here, right?
    007 is beyond physics; if you can't relate to that, have a martini, shaken, not stirred.
     
  7. Nov 19, 2006 #6
    Well there are no hard numbers mentioned here, but the final approach thrust is only slightly above idle. The aircraft is almost gliding. At full trust, altitude is gained almost immediately, also because there is a significant vertical component of the thrust vector. There is a awful lot of thrusts in those beasts today.

    It's also a safety requirement to meet certain instanteneous minimum climb rates to overcome the infamous microbursts around thunderstorms, which are guaranteed to ruin your day.
     
  8. Nov 23, 2006 #7
    Funny, last Saturday, I practised my landings in a Cessna (hadn't gone solo in 5 years), and then Sunday, I went and saw Casino Royal. I remember the scene.

    In a small plane, when you are about to land, throttle is low to idle, whereas when you take off, or decide to overshoot, you max the throttle. Flaps and gears will affect performance, but take-off and approach can be done with or without them, they are very secondary to the effect of engin power.

    It is common procedure to go from idle to max throttle to do an overshoot when needed, whether the plane has touched the ground or not. Passengers will feel the acceleration, but don't forget the engins have a lot of mass to pull, so the acceleration isn't unbearable. Not worse than when you go from 0 to take-off speed. In an overshoot, you go from landing speed > 0 to take-off speed (without the drag from the rolling wheels), which aren't actually very far apart.
     
  9. Nov 23, 2006 #8
    By the way, that was a fantastic movie. I'm so glad Pierce Brosnan is gone.
     
  10. Nov 23, 2006 #9

    russ_watters

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    I find that very hard to believe given the vast amount of drag that is added by full flaps and gear and a high angle of attack. And with a thrust to weight ratio that can't be much above .5 with the tanks empty and at full throttle, the engines can't provide more than a quarter of the lift - while reducing their ability to provide forward speed by the same 25% (at 15 degrees aoa).

    And I know they work hard to combat wind shear, but you still don't land if there is a thunderstorm nearby. There isn't anything a pilot or airplane can do if they get a significant downdraft with their nose in the air and their throttles near idle. It takes what - 5 seconds for the engines to spin up? 10 or more for the gear to come up?

    ...Except for the part about final approach being slightly above idle - I'm sure that's true, but on final approach, you are decending. With a good glide ratio, it doesn't take much decent rate to keep the speed up. That doesn't mean it can quickly transition to a climb.
     
    Last edited: Nov 24, 2006
  11. Nov 24, 2006 #10

    Danger

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    Haven't seen the movie yet, but I think that I might based upon the few clips that I've seen. The last Bond movie that I saw at all was the one with the drug kingpin (shows you what a fan I am; I can't remember the title), and I only saw it because it came on TV when I had nothing else to do. This one looks as if it has a nice edge to it, though... more in line with the original books.
    Dr., glad to see that you're keeping up. It's somewhere around 30 years since I had a chance to fly. Although you don't really get to do it much, I just loved the X-treme takeoffs (for passenger reaction); everything to the wall with the brakes locked, then kick 'em off and horse it back. :biggrin:
    And despite the signature, I never used flaps unless I had to. I prefer a clean bird.
     
  12. Nov 24, 2006 #11
    I'd just like to point out that this followed a chase in which a man on foot caught up with a full speed truck, jumped onto another truck, jumped back, and then got into a fight in the cab of the truck. So yeah, I wouldn't worry too much about the particulars of the physics there.
     
  13. Jan 6, 2007 #12
    well i've seen the movie, but i do not recall the scene. how steep was the climb?

    and while i hate to spoil the nice theory with an ugly fact, but i have been in an aborted landing AFTER we were over the runway; no touch and go; no dramatic climb. in fact we climbed very slowly as we headed down the East river. (looking in apartment windows, i was trying to recall how high the bridges were).
     
  14. Jan 8, 2007 #13
    i know that fighter jets when landing on a carrier are required (for safety) to put on max thrust before they land (hence if they miss they got plenty of speed to fly away)

    i assume the same is true with passenger planes, they are probably required to increase power just before they land and have it on just incase they need to take off again

    I’m pretty sure of it, if u notice next time you’re on a plane, when landing the noise level increases indicating that the engine is going faster
     
  15. Jan 8, 2007 #14

    FredGarvin

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    No. No. No. Two very different situations. In a carrier landing, the engines are increased to max at the moment of touchdown. The decent rate is controlled by throttle. They would not be able to land if they had the aircraft at max before they touched down.

    In an airliner, the change in throttle you hear is because the thrust reversers are employed on the engines. The engines are brought to a higher throttle to help slow the plane.

    I really have to see this movie now.
     
    Last edited: Jan 8, 2007
  16. Jan 8, 2007 #15
    humm perhaps its my wording, but thats what i ment.

    have max thrust just before you land (you can have max thrust and not even be moving) not landing with max velocity :surprised
     
  17. Sep 4, 2007 #16
    Hi folks, well being a pilot myself I had to comment on this.

    I have seen the film, and all the pilots are doing is a "Go Around".
    It is a normal procedure and on the Boeing 737/300-900 you will start to climb without hitting the deck.
    Jet aircraft come down the glide slope with 30 degree of flaps and gear down, now thats a lot of drag.
    To counter this there are Leading edge flaps and slats to help increase lift at slow speeds, say 130 Kts.
    The power setting on a 737 is normally around the 58% that is on the N1 gauge, it is the front fan speed, with a 2.5 degree nose up. Go around power is 85% ish
    To give you an idea about straight and level, at 210 kts you have 60% N1 with 6 degrees nose up and at 250 kts, 67% N1 and 4 degreess nose up both speeds are clean with no drag devices deployed.
    This is why on a cat III autoland we can have a decision altitude of 50 feet.
    Just for the record 737's have about 20-25 tonnes of thrust per engine and a 757 have 50tonnes per engine. Hope that answers your question.
     
    Last edited: Sep 4, 2007
  18. Sep 4, 2007 #17

    DaveC426913

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    Please, do elaborate.
     
  19. Sep 4, 2007 #18

    FredGarvin

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  20. Sep 4, 2007 #19

    DaveC426913

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    A whim.

    I have a tuna melt instead of a club on a whim. This guy barrel rolls commerical jets.
     
  21. Sep 4, 2007 #20

    FredGarvin

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    Well, maybe whim wasn't the right word. Rumor has it that it was not planned by anyone. I am sure that the test pilots knew exactly what they were doing and what they could get away with. Did notice how much altitude they had under them?

    Still, what a cool display that must have been. Definitely something that was done in a very different time and state of mind.
     
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