|
|
|
 71, sponsored by Beatty, was breaking the box apart--not just thinking outside it. - Kevin Ray [more] |
 |
|
|||||||
|
||||||||
Rebound Rumble ballistic trajectory with air friction drag and Magnus Effect (backspin/topspin lift/dive). For students interested in the physics, math, and computer simulation aspects of this problem. Free-body force diagram, derivation of differential equations of motion, and C pseudo-code for trapezoidal numerical integration.
Rebound Rumble ballistic trajectory with air friction drag and Magnus Effect (backspin/topspin lift/dive).
For students interested in the physics, math, and computer simulation aspects of this problem.
Free-body force diagram, derivation of differential equations of motion, and C pseudo-code for trapezoidal numerical integration.
Note: In this paper, I have used the sign convention that "g" (acceleration due to gravity) is negative. So if you are trying the integration algorithm, make sure to set g equal to -9.8 m/s/s (or -32 ft/s/s).
Attached Files
-
ballistic trajectory with drag and Magnus 2012-11-29
ballistic trajectory with drag & magnus.pdf
download file
uploaded: 11-29-2012 03:20 PM
filetype: pdf
filesize: 104.65kb
downloads: 1399
-
Appendix A: RK2 2012-12-04
Appendix A.pdf
download file
uploaded: 12-04-2012 09:20 PM
filetype: pdf
filesize: 33.12kb
downloads: 576
-
Appendix B Graphs 2012-12-10
Appendix B.pdf
download file
uploaded: 12-10-2012 08:27 PM
filetype: pdf
filesize: 1.4MB
downloads: 409
Discussion
view entire thread
12-04-2012 03:14 PM
Ether
Re: paper: Ballistic trajectory with air friction drag and Magnus
Appendix A (2nd order integration) added.
12-10-2012 08:28 PM
Ether
Re: paper: Ballistic trajectory with air friction drag and Magnus
Appendix B added. Graphs of simulation runs.
http://www.chiefdelphi.com/media/papers/2725
12-10-2012 08:39 PM
Michael Hill
Re: paper: Ballistic trajectory with air friction drag and Magnus
Pretty interesting. Unfortunately it looks like just a 2D simulation. The 3rd dimension can really play into the aerodynamics, for example, the surface velocity of a spinning ball spins relatively slower the closer you get to the "poles" of the sphere. This would be valid for an infinitely long, smooth cylinder. Not to say this doesn't provide valuable insight into how the Magnus effect affects rotating bodies in air.
12-10-2012 10:03 PM
Ether
Re: paper: Ballistic trajectory with air friction drag and Magnus
|
Originally Posted by Michael Hill
This would be valid for an infinitely long, smooth cylinder.
|
| Not to say this doesn't provide valuable insight into how the Magnus effect affects rotating bodies in air. |
For Rebound Rumble, a simulation was not necessary and perhaps not even all that helpful for the purpose of building a winning robot. This is because, as many folks have already pointed out here on CD, the major design challenge of the shooter for Rebound Rumble was to get a shooter that was consistent from shot to shot. This was a big challenge due many factors, a key one being the variation in the ball due to manufacturing tolerances and changes in the ball's physical characteristics as it got worn. Once you've built the most consistent shooter you can, it's a simple matter to test-fire it to determine its performance.
12-11-2012 06:27 AM
Michael Hill
Re: paper: Ballistic trajectory with air friction drag and Magnus
Hmm, perhaps you're right (capital D instead of lowercase D in CD). However, finding the correct constants aren't so trivial.
12-11-2012 06:27 PM
Ether
Re: paper: Ballistic trajectory with air friction drag and Magnus
|
Originally Posted by Michael Hill
Hmm, perhaps you're right (capital D instead of lowercase D in CD). However, finding the correct constants aren't so trivial.
|
Set um=0 and adjust ud to match the trajectory1 with no spin.
Leaving ud at that setting, adjust um to match the trajectory with the expected spin. (repeat to get um's for various spins if needed).
Then I'd launch the ball at various angles (and speeds) and see how well the simulations matched the actual trajectories1.
It would make an interesting science project.
1Probably need a high-speed frame-timestamped video camera to determine launch speed, angle, spin, and trajectory
view entire thread
Tags
loading ...