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 Golf Ball fligth path calculation « View previous topic :: View next topic » 
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andyfive
PostPosted: Sat Feb 05, 2011 3:47 pm    Post subject: Golf Ball fligth path calculation Reply with quote

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Joined: 03 Feb 2011
Posts: 1

First of all, thank you very much for the TrajectoWare software and all the useful information on http://www.tutelman.com/golf/ballflight/index.php.
I am trying to develop my own ball flight model and this information has been extremely useful in understanding all the different factors that are involved. The model I am trying to develop is ball flight only, given initial initial launch characteristics such as launch angle, velocity, spin rate/angle etc. and so club characteristics are of no concern. Having said that, I would like my model to work given any initial ball flight characteristics that may be generated from any club, SW to Driver (I believe this may be the only shortcoming of TrajectoWare and the model used by John C. Adams). I would also like to bring the effect of wind into the calculation.
My model is initially being developed using a spreadsheet but eventually would like to develop code to show a 3D representation of the ball flight. I have searched the internet for suitable formula for calculating ball flight and have come across a number of methods used including this one ( http://www.webnucleo.org/home/online_tools/newton/0.4/html/about_this_tool/tutorials/golf_1.shp.cgi ).
Does this formula seem accurate to you? For me, it seems to omit spin rate (just seems to use angle of spin) and also uses constants to calculate the Drag/Lift Coefficients so would question its accuracy. Also, I cannot for the life of me work out how the wind comes into this equation (u=v-vw seems to simplistic to me as wind can be from any angle so presumably needs to be applied in all 3 dimensions?). Do you think this formula is suitable or is there another formula or method that you could recommend for me or maybe I could adapt the formula you have used in TrajectoWare to work for spins produced by different clubs? Apologies if some of these questions seem stupid or a bit basic but my background is IT and not physics (I am learning the physics as I go along Very Happy )

Many Thanks in advance.

Andy.
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dtutelman
PostPosted: Sat Feb 05, 2011 5:06 pm    Post subject: Re: Golf Ball fligth path calculation Reply with quote

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Joined: 09 Apr 2007
Posts: 105
Location: New Jersey, USA

Andy,
You have indeed figured out the biggest flaw in that model. They have no explicit inclusion of spin. In fact, they do not even allow the input of spin angle. They derive both spin and spin angle from the initial velocities. Does not work!

I also think I have trouble with their CD and CL, as well as their treatment of wind. But I didn't look at these very hard once the big flaw was exposed. No point in bothering.

Sorry,
DaveT
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Mitchellharris
PostPosted: Wed Jun 26, 2013 6:39 am    Post subject: Reply with quote

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Joined: 26 Jun 2013
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May be if someone would share some demonstration video so that everyone can also understand the basic of it in more detail.
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dtutelman
PostPosted: Wed Jun 26, 2013 3:03 pm    Post subject: Reply with quote

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Joined: 09 Apr 2007
Posts: 105
Location: New Jersey, USA

Not a video, but I have some diagrams in http://www.tutelman.com/golf/design/swing3.php

BTW, I have looked again at the article. It is not as bad as I first thought. True, there is no explicit inclusion of spin, which is a fatal flaw. The formulas for CD and CL seem to assume some sort of "average" spin, but not the ability to adjust spin. But they do include spin angle. And the wind is included properly. Remember that velocities are three-dimensional vectors. The formula U=V-Vw must be applied in three dimensions (though only two make sense for wind).
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