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Building a glider

  1. Apr 19, 2008 #1
    i have a project for physics where i have to build a glider, its going to be flown in a hall way, so it shouldnt be too big. however, i dont really know of any designs that would work well so any ideas?
     
  2. jcsd
  3. Apr 19, 2008 #2

    Danger

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    Welcome to PF, Katie.
    If you've read the forum guidelines, you know that we don't provide answers flat-out to schoolwork. You'll have to show what you've attempted already, what resources you've accessed, etc.. There's a lot of information about gliders available.
     
  4. Apr 19, 2008 #3
    There are some interesting glider designs, but the best ones require to be thrown of a big height.

    If you need a glider to be launched in a hallway, what are the conditions? Is it going to be thrown? Is there a limit speed? Can you add some kind of an engine? Elaborate please.

    Oh btw, if you are going to compete length-wise, a small rock can travel further than any glider you can build.

    Even though that's probably not legitimate
     
  5. Apr 19, 2008 #4
    The only form of propultion will be from the person throwing it. Its basically gonna be measured for distance and time. And no engines lol, this is jut grade 10.
     
  6. Apr 19, 2008 #5
    Well then, make sure it's long ( I think), with a heavied nose. And big wings.
     
  7. Apr 19, 2008 #6
    I've been looking online and noticed there were many different kinds.. theres this human glider
    transportcafe.co.uk/trucking_photographs_english_countryside_microlites/microlite_glider_pair.jpg

    im not sure if that would work as a smaller model, plus it seems confusing with all the supports involved in it.
     
  8. Apr 19, 2008 #7

    rcgldr

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  9. May 26, 2008 #8
    Hello everyone!

    I'll be very glad if anyone can help me to find any information about the relation between the wing span and total length of a glider or a sailplane, I have found that this value is between 30 to 50% but there are any mathematical expression to find this value?

    Thank you very much!
     
  10. Oct 21, 2008 #9
    Hello all.

    I am a student teacher right now but my cooperating teacher and all the other tech teachers do a hallway glider activity. It is great and you can teach measurement and bernoulli's principle and newtons 3rd law.

    you construct it out of one side of a manila file folder. you make a rectangle that is 11''x4'' that is the body you bend two sides down at a half inch on either side. You create an air scoop at the front. you put two 3x3 stabilizers on it and tape a paperclip to the bottom.

    You have to build a launcher that is basically a peice of wood with a slit cut out of it the that will give you enough room to pull back the glider with variable intensity. You can then use a rubber band attached to either side of the front of the wood to launch the vehicle. My cooperating teacher made a big one at 4 times scale and launched it with a bungee chord. WOW it went over 150 feet!
     
  11. Oct 21, 2008 #10
  12. Oct 21, 2008 #11
    go to the nasa sight and watch the video of the wright brothers
     
  13. Oct 23, 2008 #12

    rcgldr

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    This web page has a couple of videos of a catapult launched glider with a restrictive 39 foot ceiling.

    catapult glider videos

    Another AMA indoor glider web page, with a pair of pictures of a hand (discus style) launched model. Here the model reached height of 100 to 115 feet, and longest flight time was 1 minute 42 seconds, a record.

    indoor hand launch glider.htm]

    Be careful with this. A lot of Bernoulli based articles on lift are misleading.

    The short version for lift explanation is that an aircraft uses an effective angle of attack and forward speed that diverts air downwards and a bit fowards. Newton's 3rd law: the aircraft exerts a downwards and somewhat forwards force onto the air and the air exerts an upwards (lift) and somewhat backwards (drag) force onto the aircraft. Newtons 2nd law: force equal mass time acceleration (how the air is affected). Bernoulli: the total energy of a volume of air is the sum of temperature (usually ignored), pressure, and kinetic energies. How a solid interacts with the air: air is accelerated via pressure differentials near a solid and by mechanical interaction with the solid (or with the thin surrounding boundary layer), such as collisions, vortice generation, friction, ...

    The imporant aspect of Bernoulli is that by reducing pressure while accelerating the air, the increase in kinetic energy is offset by the reduction in pressure, reducing the total amount of energy added to the air, which reduces the work done by a wing. The other obvious way to reduce work done by a wing is to reduce the increase in kinetic energy. Accelerate twice as much air at 1/2 the rate of acceleration, and you get the same lift, but only generate 1/2 the kinetic energy. This is why high end gliders have 80 foot or longer wingspans and manage 60 to 1 glide ratios. For smaller model gliders, an issue due to vicous versus inertia forces is called Reynolds number, and the smaller model gliders need a longer wing chord.

    Note that a wing always peforms some amount of work on the air, and any change in the total energy of the air requires a non-Bernoulli like mechanical interaction, an increase in pressure without a corresponding decrease in speed^2 and/or vice versa.
     
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