1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Paper plane physics question

  1. Nov 7, 2011 #1
    Hello Guys.

    Maybe you got in the past some similiar questions :)

    I'm a game developer and I'm programming a game with a paper plane and I want to achieve a nearly real physic.

    What I got so far:

    trust = the speed when I throw the paper plane.
    drag = dragcoefficient * airdensity * trust² * surface / 2
    lift = 0.5 * airdensity * velocity² * wingarea * lift coefficient
    gravity = weight * 9.822 / (24 frames per seconds)
    velocity = trust - drag - lift + gravity

    So, my problem now is this:

    • the correct lift coefficient:
      How can I calculate the lift coefficient with aoa? Here on this forum I found the following formula:
      Cl = Cl(2d slope) * (AR/AR+2)*aoa

      But what is 2d slope, and how can I calculate the Cl when I don't have the Cl? And what is AR?
    • When I throw the paper plane, and it's moving upwards, the speed is increasing. But it must be decreasing:
      I know, that I calculate the lift into velocity. So it must be increasing. But how is it in reality?

    Greetings and thanks

    Wolv3r
     
  2. jcsd
  3. Nov 7, 2011 #2
    Paper airplanes (at least the ones I use) have no internal thrust; no motors, engines, or propellers. They are therefore more like gliders and less like true powered airplanes. This means that unless they hit an up-drafting air current which externally provides lift, the paper airplane can only fall over the long-term. It can momentarily ascend as part of its overall downward path, but only at the expense of its forward momentum. It momentarily exchanges kinetic energy for gravitational potential energy (like a pendulum).
     
  4. Nov 7, 2011 #3

    rcgldr

    User Avatar
    Homework Helper

    The 2d slope is the CL versus AOA curve for a 2d (idealized) wing, which would be similar to a wing with infinite span. AR is aspect ratio, the (wing span) / (wing chord). Link to a web page about paper airplanes:

    http://paperplane.org/Aerodynamics/paero.htm
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Paper plane physics question
Loading...