how an airplane decollate technique

Discussion in 'Rules and Regulations / Flight Safety / Better Pil' started by kondordv, Feb 8, 2007.

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  1. Feb 8, 2007 #1

    kondordv

    kondordv

    kondordv

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    how an airplane decollate

    Hi all,

    real pilots or virtual pilots, something is not very clear for me in flying if someone can explain to me I'll be very happy.

    Let me explain to you. In decollating an airplane runs with high speed. At the moment when the airplane leave the land what happen? The airplaine is climbing because the flaps are activated and the air direction is changed? Or the airplane is climbing because the portant force (appeared from air pressure difference)? If there is the portant force as phisics say it, is it someone to tell me how we calculate this force and what speed it is necessary to lift an airplane of 100 kg?

    thank you all,
    Kondordv:depressed
     
  2. Feb 9, 2007 #2

    Craig

    Craig

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    When taking off, the airplane accelerates. As the speed through the air increases, the air over and under the wing begins to create lift. When enough lift has been generated, the airplane flys.
    Lift speeds change with differently shaped airfoils.
    And yes, moving the 'flap' - meaning the moveable horizontal control surface at the back better known as the 'elevator' - changes the pitch attitude of the aircraft. The rudder controls 'yaw' - the sideways motion of the nose, and the 'ailerons' on the wingtips control motion around the longitudinal axis.
    That's about as simple as I can put it. And no, I can't calculate lift on a 100 kg airplane.
    What country are you from?
     
  3. Feb 9, 2007 #3

    orion

    orion

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    First, what do you mean by "decollate" - no such word associated with airplane design.

    As far as calculating the speed for lifting a 100kg airplane, that is sort of a meaningless question since you'd have to define several variables before such an effort could be meaningful. And no, airplanes do not need wing flaps to take-off.

    To do this you must define the airplane, select a specific airfoil and wing loading, which in turn is used to define the wing area. All this then has to be somewhat optimized for available power, desired operating envelope, payload, etc. Generally, designing an airplane or providing you with the process is really beyond the scope of this type of discussion board.
     
  4. Feb 9, 2007 #4

    Norman

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    Hi, Kondordv

    I think what you are looking for is the "coefficient of lift" cl for short . To calculate how much weight a certain size wing will carry at a certain speed you would look up the cl for that wing at it's best glide angle and use it in this formula:

    L= 1/2 x p x V^2 x S x cl

    Where:
    L is lift
    p (greek letter Rho) is 1.225 kg/m^3
    V is velocity in meters per second
    S is wing area in square meters

    Notice that speed (V) is squared in the formula. Say that you have a 1 square meter wing that can fly straight and level at 100 km/h with 10 kg. The same wing can carry 40 kg at 200 km/h
     
    Last edited: Feb 10, 2007
  5. Feb 12, 2007 #5

    Midniteoyl

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    Bill, sounds like he used a site like 'babblefish' to translate... not very accurate.
     
  6. Feb 28, 2007 #6

    wsimpso1

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    I think I understand the question - the translation did not work into aviation english very well. I hope that our responses work better...

    Lift is a function of several things:

    Lift = (air density/2)*air velocity^2*wing area* wing coefficient of lift

    Lift increases as the airplane speed increases

    The wing coefficient of lift (Cl) is a function of wing angle of attack. For symetric airfoils, at zero angle of attack you have zero Cl. Increase the nose up attitude, the angle of attack increases, and so does the Cl and the Lift. At high speed, very little angle of attack is necessary. At takeoff speed, the nose has to be fairly high.

    Ever watch an airplane takeoff? It runs up to takeoff speed, but is still firmly on the ground. Then the pilot deflects the elevator to push the tail down, increasing the angle of attack, and the airplane then is making enough lift to leave the ground. Watch it as it climbs, and you will notice that the nose is directed higher than actual direction of flight...

    Flaps are on the wings, elevators on the tail...

    Flaps can have some or all of these effects:

    Flaps can increase wing area;

    Flaps can shift the coefficient of lift vs angle of attack curve higher;

    Flaps can add drag.

    I hope that this helps.

    Billski
     
  7. Feb 28, 2007 #7

    wsimpso1

    wsimpso1

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    Hey, I just looked up the word decollate (thread title is "how an airplane decollate", and my dictionary has two definitions:

    Remove the head, as in decapitate (which might relate to "taking off")

    Clothing without collars, or open necklines, etc.

    Interesting how that translated...

    Billski
     
  8. Mar 17, 2007 #8

    kondordv

    kondordv

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    Re: how an airplane decollate "take off" technique

    Hi all again,

    after long time spending to find and understand the principle of flight and take off for an airplane, I found the answer and it is as I was expected. The Bernoulli principle (Popular explanation) depending of different wing foil, is not enough for an airplane to take off, but Phisical Description (angle atack of wings) is more used and understandable.

    Anyone of you has this two things not very clear in flight technique please visit the page below. The explanation is very very clear.

    http://www.allstar.fiu.edu/aero/airflylvl3.htm

    :)
     
  9. Mar 18, 2007 #9

    CAB

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  10. Mar 20, 2007 #10

    RonL

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    Thanks to both of you for links that will answer, and help with many things that up till now have been less than clear.

    RonL
     

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