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SK200 Sidecut radius??

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Postby Sam » 28 Jan 2003 16:28

:huh:
Hi,
Does anyone know the sidecut radius of a Lacroix sk200?

Cheers,
Sam
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Postby Zarkod » 29 Jan 2003 11:46

I can tell you that it is the same than the Lacroix Contest radius, because we compared them at the last Contest with Tantouse de Reus and the shape is strictly the same, what differs is the fexibility and structure.

I think than the radius is 15 meters but i'm not sure, it would be better to make some measurements of the board and deduce the radius, I will try to do that when I have some time.
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Postby Sam » 30 Jan 2003 11:25

:D

Hey Thanx Zarkod!!!

Does this mean that the SK200 has a big simularity with the 183°F, because of it's measurements? Or is it not possible to do a simple comparation like that?

Cheers,
Sam
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Postby Zarkod » 30 Jan 2003 11:46

The SK200 is 180 centimeters long, and I did not compared it to the 183°F but it is in the Thias range the more similar to the SK200.
Lacroix Contest and 183°F are defenitely recommended for best carving sensations.
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Postby Sam » 30 Jan 2003 16:58

Thanx again Zarkod!

What does a 180 freecarve better (or worse) than an sk200 (or other 15m radius skwal)?

In other words,

What are the positive/negative sides of a short radius?

ciau,
Sam
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Postby Zarkod » 30 Jan 2003 17:08

The FC 180 is the more polyvalent skwal among Thias products. It is very efficient in the powder with its large head and tail, you will not go as fast as a with a Contest or 183°F but the carving sensations are similar with its well-balanced shape, and it is a bit more practical if there are a lot of people in front of you!
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Postby Sam » 30 Jan 2003 17:14

Hey,

Thanx for the quick reply!! :D :lol:

I'm not fast enough to think of my next smartass question! :P

CU
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Postby Zarkod » 03 Feb 2003 17:20

Last Sunday I made some measurements on my SK200 :

tip widest point : 160 mm (at 1670 mm from the tail)
center thinner point : 114 mm (at 750 mm from the tail)
tail widest point : 153 mm (at 45 mm from the tail)


with this link we can calculate the sidecut radius :
<a href='http://www.math.utah.edu/~eyre/rsbfaq/physics.html' target='_blank'>http://www.math.utah.edu/~eyre/rsbfaq/physics.html</a>

Does anyone want to try, i'm a bit lazy...
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Postby Sam » 04 Feb 2003 10:30

Thanx Zarkod, :D
Ok, I tried to calculate (everything better than working it self). :huh:
The formula from this Utah education site is followed:

Rsc = ( (L^2) /4 + d^2) / (2*d)

With:
Rsc = Sidecutradius (m)
L = (see picture)
d = (see picture)

A little problem I had was that the front is wider than the tail. And the formula only works when the side is cut according to a arc and not an elyps (like most skis). :(

Assumed that the sidecut is a perfect arc I calculated as follow: :rolleyes:

d = Tail/2 – Middle/2
L = ‘Tail to Middle’ * 2

Tail = 153mm
Middle = 114mm
Tail to Middle = 750mm

d = 153/2 – 114/2 = 19,5 mm = 0,0195m
L = 750 * 2 = 1500mm = 1,5m

Here we go: :blink: :blink:

Rsc = ((1,5)^2 /4 + (0,0195)^2) / (2*0,0195) = (2,25/4 + 0,00038025) / 0,039 = 0,56288… / 0,039
Rsc = 14,44m

But, I’m not a Maths expert, so please don’t take it to absolute!! B)
Thanx for the measurements and formula,

Cheers,
Sam
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Postby Zarkod » 04 Feb 2003 11:21

I think you should try with
L = 1670 - 45 = 1625 mm the distance between the widest point at the tip and the widest point at the tail
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Postby Sam » 04 Feb 2003 16:58

But what would that make d?

I mean, the two widest points are not equal, so you should extent the Sidecut arc untill it cuts the L-line. The distence between the widest point at the Front and this crossing is than the right L.

(assumed that the sidecut radius is a perfect arc..)

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Sam
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Postby Zarkod » 10 Feb 2003 13:36

I think that the best measure would be to locate the point where the tip is 153 mm wide and to
look at the distance between this point and the tail widest point (153mm wide also).

Unfortunately I do not bring my SK200 with me at work :D
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Postby Zarkod » 12 Feb 2003 19:41

I made some better measurements that should improve the calculation :)

149 mm at 45 mm from the tail
114,5 mm at 795 mm from the tail
149 mm at 1526 mm from the tail
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