How to calculate turn radius/sidecut?

[nest]

I am looking to buy some new skis and and wondering how they calculate sidecut/turn radius. For example I am interested in the new apache chiefs whose turn radius (on the website) is 23m for the 174. Would the 188 have the same turn radius? The blizzard 9.2 (also in a 188) has more sidecut but still lists the same turn radius (23m) so I am a little confused. The dimensions of the apache are 126/98/116. How do they come up with a 12mm sidecut or 23m turn radius? Thanks

[crashnburn'd]

The radius will vary by length because the width dimensions of the ski are kept the same (for the most part, I think). I always assumed the radius was the size of circle the the sidecut would make if it was extrapolated.

[Theodore]

As found with a giant sheet of paper and a pencil.

[Tri-Ungulate]

Warning - techy geeky OCD link below:

http://www.math.utah.edu/~eyre/rsbfaq/physics.html

That oughta give you what you need to figure out what you're asking.

edit:

I should add that sidecut radius and turn radius are different things, and actually kinda inversely proportional. Also, despite the way the calculation is described in the above link, different ski companies sometimes use different methods to either measure the variables in the calculations, or maybe even use different formulas, or sometimes I think they just make the shit up as part of their advertising copy.

[summit]

You'd need to know more than just basic sidecut dimensions... you'd need to tknow the actual shape of the sidecut andh te flex profile of the ski... then some calculus for you!

[Tri-Ungulate]

You'd need to know more than just basic sidecut dimensions... you'd need to tknow the actual shape of the sidecut andh te flex profile of the ski... then some calculus for you!

True, dat.

I usually don't even bother with all that shit (sidecut radius, turn radius, flex weight, etc etc), to be honest. Just check out the profile specs (thoe aren't too subjective), eyeball the overall edge shape and flex the ski to get an idjicated guess in the shop of how it might ski.

The most useful paramater might be edge contact length, like the snowboard companies give.

[nest]

thanks. that is exactly what I was wondering. so the turn radius on the 188s would be significantly longer, assuming all variables are the same except length (around 3-5m by my very rough estimate, no trig function calc.) than the 174s. Of course im an idiot so im probably way off.

[bad_roo]

You're no idiot if you've found Jesus.

[PhysicsMan]

Here's a simple, fill-in-the-blanks (actually, overwrite-the-existing numbers) spreadsheet to calculate sidecut radius:

http://www.websurd.com/epic2004/PMSidecutRadCalc.xls

The instructions are here:

http://forums.epicski.com/showthread.php?t=2681

FYI, there is at least one huge thread over on Epic at the start of every season about the difference between turn radius and sidecut radius. Do a search.

HTH,

Tom / PM

[nest]

perfect, retard-proof calculations, thanks physicsman.