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Designing a lab about flight

  1. Sep 10, 2008 #1
    1. The problem statement, all variables and given/known data

    I'm supposed to design a practical about factors that affect flight. I've decided to use Bernoulli's Principle to help me do this experiment. So I am planning to alter the thickness of the wing (independent variable) see its effect on the horizontal displacement (dependent variable).

    So I just want to know if this is feasible... and is there a relationship between it? Or maybe i should have the angle of the wing as my independent variable and the horizontal displacement/speed for my dependent variable? If it is not feasible, what do you think I should alter on? What relationship there is between the independent variable and dependent variable?

    Thanks
     
  2. jcsd
  3. Sep 10, 2008 #2
    That lab sounds a little hokie to me since the wings displacement will be affected by what it is holding it in place and allowing the displacement. If you want to show the affects of the Bernoulli principle I would either adjust the angle of the airfoil or the velocity of the airflow and then measure the lifting force. The force will have a direct and somewhat proportional relationship to the airfoil angle and/or air speed.
     
  4. Sep 10, 2008 #3
    is there a formula for the relationship? And what do u mean by velocity of airflow?
     
  5. Sep 10, 2008 #4

    LowlyPion

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    The Bernoulli effect is the effect of a faster moving fluid having a lower pressure. The pressure differential is what lifts the wings. Hence by having something - a fan say - move air at different input velocities you can demonstrate lift in a wing cross section. The greater the path length differential, the greater the speed, the greater the lift. Alternatively you can show different cross sectional effect with the same velocity.

    2 parallel surfaces - no lift
    1 flat, 1 convex on top - + lift.
     
  6. Sep 11, 2008 #5
    So by wing cross section you mean is the thickness of the convex of the wing? Can I do that for my independent variable? Or the angle of the wing (the tilt)?
     
  7. Sep 11, 2008 #6

    LowlyPion

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    I'd go with thickness, because that demonstrates the principle. Tilting is adjusting the angle of attack. You can do a kite for that.
     
  8. Sep 11, 2008 #7
    Alright! And do you think I should make the plane and throw it around and see its horizontal displacement or put it in front of a fan and see how much lift it gives me? Sorry for asking a lot, I'm kind of blank about this topic :P
     
  9. Sep 11, 2008 #8

    LowlyPion

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    Throw a plane? What does that show that you can measure?

    I'd build a box with plexiglass sides and a blower across (uniformly as you can get it) the opening flowing over top and bottom (front to back of course) with a wing cross-section that provided a semi decent seal across the box and have it attached to a spring, and guides to constrain it to only go up or down, not flop around. Then you can turn the fan on and mark how high it rises.

    Then you can determine the spring constant and identify how much lift you achieved.
     
  10. Sep 11, 2008 #9
    Ah... I wish this forum have a sketch post or something.

    Well, thanks a lot then! I think I can imagine what it looks like now.
     
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