Ski Racing Line Versus Auto Racing Line?

jyl · jyl's Garage

I've been watching ski racing on TV lately. My favorite is the downhill. Today they were showing helicopter overhead shots of the racers on the Wenger course. This course reminds me of an old-time European road racing course - it flows down the terrain, along an old 4x4 track, into a chute and through a tunnel, then some turns that look like the corkscrew at Laguna Seca. It is about 2 1/2 miles long and the men get up to appx 80 mph.

As I was watching the overhead shots, I started thinking how fun it would be to drive that course if it were paved - and maybe a little less steep. That got me wondering,

What is the difference in the line you take as a (solo) auto racer, versus the line you take as a ski racer? And why the difference?

Just my impression, was that the ski racers seem to apex earlier (oops, I initially said "later") than an auto racer would.

Why? Ski racers are trying to conserve momentum, their only acceleration is gravity, and turning slows them down. Autos brake into turns and accelerate out of them, and have more braking power than acceleration power. But I am not totally clear how this influences their racing lines.

What do you think?

Here are a couple YouTube videos of the Wengen course.

YouTube - Fritz Strobl WENGEN Downhill (2003???) start at 1:00, this video has a good overhead shot

YouTube - Wengen Mens Downhill 2007c

YouTube - Didier DEFAGO the winner of Wengen World Cup downhill 2009

mattdavis11 · 01-15-2010, 06:21 PM

Inertia

jyl · jyl's Garage

I thought about this some more. A ski racer is kind of like a underpowered car. He has to conserve as much speed as he can. Don't underpowered cars want to apex earlier than cars with lots of power, who want to get the turning done quickly so they can get on the throttle as soon as possible?

Tobra · Tobra's Garage

So skiiing is like driving a 914 then.

s_morrison57 · 01-16-2010, 04:06 AM

I took a Jim Russell driving school at Mont. Tremblant on the old Canadian F1 circuit and the instructor then, 1990, said that the Canadian Downhill ski team took the course so they could relate to the corners of the track as opposed to the down hill and I think the out come was the same, ski it like you would drive it. Very cool track by the way

widgeon13 · 01-16-2010, 04:34 AM

Keep a flat ski on the snow as much as possible, aerodynamics is critical in downhill skiing, staying in the tuck position whenever possible

Tervuren · Tervuren's Garage

Quote:

Originally Posted by jyl

I thought about this some more. A ski racer is kind of like a underpowered car. He has to conserve as much speed as he can. Don't underpowered cars want to apex earlier than cars with lots of power, who want to get the turning done quickly so they can get on the throttle as soon as possible?

Actually, when I'm driving a heavier underpowered kart I tend to hit very late apexes. An early apex causes the need for a huge amount of turning out the other side, but more entry speed. I'd like to see a video of what we are talking about though to know what skiers are doing. If you are coming up on a very steep slope, then you could use an early apexe to slow your self down, the hard turning out the exit would give you a slower speed on the straight so you can go into the next corner in a more controlled fashion.

jyl · jyl's Garage

Look at the videos I linked to. Different racers, all on the same course.

Ski racers don't want to slow down. Different from recreational skiers who turn to slow down. AFAIK, a ski racer will never deliberately slow himself down for a turn.

berettafan · 01-16-2010, 05:57 AM

don't ski but my guess would be ski racers don't 'drift'.

Dantilla · 01-16-2010, 06:35 AM

Quote:

Originally Posted by jyl

Don't underpowered cars want to apex earlier than cars with lots of power, who want to get the turning done quickly so they can get on the throttle as soon as possible?

Every driver, no matter how much power he has, wants to get on the throttle as soon as possible. The ideal line for an underpowered car is the same as the line for a high horsepower car.

While every turn is unique, a late apex allows for earlier throttle.

jyl · jyl's Garage

Skis can skid (drift) or carve. Recreational skiers will sometimes deliberately skid in order to slow down. Racers try not to skid, although in some very tight turns they have to skid briefly at the beginning of a turn.

speeder · speeder's Garage

Quote:

Originally Posted by berettafan

don't ski but my guess would be ski racers don't 'drift'.

They actually "drift" quite a bit at times but just like in a car, the fastest way through a corner is going forward as opposed to sideways. Balancing the various forces of physics leads to a compromise and skidding at times, exactly like a car on a racetrack.

When I started doing track events in a car, it reminded me completely of skiing and specifically slalom when there are series of connected curves. When you are really cooking in a car, you aim for the apex like you want to hit it too much "inside" and the sliding of the car makes you just miss it, exactly like a slalom pole. You do not ski in big curvy loops around slalom poles, it more like an almost straight line. Auto-x would be a very close analogy but I've never done it.

Anyone who has ever raced on skis and then drives on a race track cannot miss the extreme similarities.

speeder · speeder's Garage

Motorcycles on a track would be an analogy of a perfect ski race run but there is always skidding on skis.

bell · bell's Garage

Actually......if you've ever skated or bmx'd a halfpipe you'll understand this better.......
"Pumping" in the transition will increase speed, hence let you get more air, the same rule applies in skiing and snowboarding, when you're on your edge you can "pump" out of the corners and gain momentum, the faster you're going the edge will dig in more with the right conditions, so speed increases if done right

berettafan · 01-16-2010, 07:21 AM

Quote:

Originally Posted by speeder

When you are really cooking in a car, you aim for the apex like you want to hit it too much "inside" and the sliding of the car makes you just miss it, exactly like a slalom pole.

Yeah this is what i was referring to. Didn't realize skiing is the same way.

Maybe I can beat my time on the Wii now!

Tidybuoy · 01-16-2010, 09:21 AM

Quote:

Originally Posted by berettafan

don't ski but my guess would be ski racers don't 'drift'.

You definately can drift on skis. It simply depends how hard a trun you need to take. If you carve hard, you legs feel it and you grip the slope. if you don't carve as hard, you drift.

Sometimes, due to very high speed, it's almost impossible to carve and not drift - just watch the downhill racers that are going really fast and both skis look like they are hopping. This is cause they are drifting and they can't carve perfectly (beleive me, they are doing everything they can to carve but muscles have their limits).