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# How many Gs?

How many Gs do racers pull in a sharp turn: .
How many Gs does the typical wannabe racer pull on SLs, GS, SG, DH: .

A G being defined as acceleration equal to 9.8 m/s/s or 32 ft/s/s.
I read a line from Bode's book which played on why ski racers have such large leg muscles, he said it was in part due to having to withstand upto 4G's in high speed turns...im guessing that's in DH or SG
Did a quick and dirty calculation using A = v²/r.

If a skier is going 50 miles/hour and makes a 20 meter radius turn, then the skier is pulling about 2.5 Gs.

Change everything into feet and seconds. Don't forget to divide the Acceleration (A) by gravity which is 32 feet/sec².
i hated pvnrt. Hated you back in freshman chem and still hating you now
Well......OnStar.......I don't like General Motors' products, either.

Thinking about my recent post. A skier doing 50 miles/hour would probably making turns with at least a 40 meter radius. This would bring the G-force down to 1.25 Gs.

Or, maybe, I'm just doing the wrong calculation.
Interesting problem. I don't know if the weight numbers on a universal gym are accurate, but they would suggest that I would collapse around 3 g's. Figure while skiing, without the benefit of a static equally ditributed weight it would be more like 2g's.

If I jab too fast a turn on my slalom skis on grippy snow, say 15 m at 40mph I know I'll get put right on my ass.
Quote:
 Originally Posted by newfydog Interesting problem. I don't know if the weight numbers on a universal gym are accurate, but they would suggest that I would collapse around 3 g's. Figure while skiing, without the benefit of a static equally ditributed weight it would be more like 2g's. If I jab too fast a turn on my slalom skis on grippy snow, say 15 m at 40mph I know I'll get put right on my ass.
Machines don't count. In college, starting with my knes at about 45 degrees sitting in the chair I "leg pressed" easlily over 10 times my weight. I think it was 1600 lbs (memory fades; it was a loooong time ago). A good thing I had a witness 'cause nobody believed a skinny little guy like me was that strong.

I can do the V^2/R thing too, but I don't know how much the Ice can hold. 13 m radius at 88 kph yields about one turn per second and 4.7Gs. No wonder my legs are a little stiff.
A few years ago at a USSA clinic:
GS turns with an edge angle of 60 degrees to the snow= 2 G
Gs turns with an edge angle of 70 degrees to the snow= 3G

Don't know how accurate, but sounds good.
Quote:
 Originally Posted by KeeTov A few years ago at a USSA clinic: GS turns with an edge angle of 60 degrees to the snow= 2 G Gs turns with an edge angle of 70 degrees to the snow= 3G Don't know how accurate, but sounds good.
That might be approximately right, but theoretically, the angle of the edge to the snow is irrelevant.
If the angle between vertical and the line through your base of support and center of mass is 60 degrees, the turning force will be 2g's, regardless of the edge angle or slope angle. The total force on your body, including gravity, will be about 2.2 g's.
USSA coaches are great, but I think most of them slept through physics class.

BK
Bode Klammer is right that the angle that's relevant isn't the edge angle, but the angle of inclination, i.e. the angle of the line from the base of support (if the racer is entirely on his outside ski, that would be the inside edge of the outside ski) through his center of mass (somewhere around the hips or the bellybutton). The edge angle is often higher, because of angulation.

If you make that change to what the coaches said, though, I think they're otherwise about accurate.

Picture the skier coming at you. Draw a horizontal line from his base of support toward the inside of the turn. Draw a vertical line down from his center of mass. Draw a diagonal line from the support to the center of mass. You've drawn a right triangle in which: the vertical line represents the acceleration of gravity, the horizontal line represents the sideways acceleration of the turn, and the hypotenuse represents the total experienced by the skier. The angle at the base of support is 90 - angle of inclination. So:

Total acceleration = G / sin (90 - angle of inclination)

At 60 degrees: 1 / sin (30) = 2.00 Gs
At 70 degrees: 1 / sin (20) = 2.92 Gs
I have heard that for most wanna-be racers that the g-force is between 2 and 3 G's usually. At higher speeds WC'ers are getting well over 3 and 4 G's. I would expect that in race type turns (especially high speed GS and SL) the force is around 3G's. I can squat quite a bit, but it doesn't translate directly to what I support on skis, as I am skeletally stacked when skiing... so skiing you can support a lot more. I can only squat about 315...

Later

GREG
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