audi and kaipola ski jump advertisiement - climbing an icy hill

37.5 degrees actually.

Graham

Cant be 80 degrees. That's absurd.

A quick Google found an interesting article:

I wonder if the AWD was really useful at that angle. RWD should have been enough.

You really should study physics a little...

Not 20 minutes after my last post, I saw the commercial itself!

In a given distance it rises 80% of that distance. Tomes

Yes.

But the original poster said 80 *degrees*. He had clearly mistaken one for the other or heard about it from someone who'd been so mistaken.

So how did they get 0.8 from 37.5 degrees? Is that the tangent of the slope angle? It is close numerically, but it doesnt sound right, as it can exceed 100%. Or is the sinus? That doesnt match numerically with 0.8.

Your observation is correct, it's the tangent function. Gradient is the ratio of vertical elevation -vs- horisontal displacement, and with slopes greater than 45 degrees the vertical elevation goes up faster - hence it is possible for gradient to measure past 100% .

For instance, the gradient of a ladder leaning against a wall can be several hundred %'s, and the gradient of an upright wall itself is as much as infinite... :-)

Cheers!

- Risto -

Why? We are talking about an angle of 37.5 degrees here which can be done with most 4x4's with low range T-case. On tarmac you will even succeed without spinning wheels. Kind regards, Erik-Jan.

The message from "Risto Lankinen" contains these words:

Or possibly even negative if your builder's had one too many for lunch.

Percentage, as written down on the warning traffic signs (e.g.,

and is defined as thevertical distance ascended (or descended) versus the horizontal distancetravelled, 100*b/a in the following diagram: /| / | c/ |b / | /____| a

This is the tangens of the angle between sides c and a. The gradient is also given as 1:X, but this is just the fraction b/a written as 1:(a/b).

Here's a table of some gradients in degrees and percentages, both rounded to 0 decimal places:

deg | perc. ===========

90 | infinity 45 | 100 31 | 60 30 | 58 27 | 50 17 | 30 14 | 25 6 | 10

Pooh Bear, was motivated to say this in rec.autos.driving on Wed, 18 Jan 2006 01:41:37 +0000:

38.66 degrees (assuming I did the trig right)...

It's actually a lot of fun doing that!

We regularly used to take our Jeeps out to a local sand pit area before it closed that is challenging in the summer and run it in the winter. It is a blast and our 4x4's can climb wicked slopes in snow. Way more than 37.5 degrees.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

A slope *can* exceed 100%, because yes, it is the tangent of the slope angle. A 45 degree slope is 100%.

Your missing the point. At 37.5 degrees, almost the entire weight of the vehicle will be on the rear wheels. Take a wheelbase of 8' for example and assume a 50-50 weight distribution. If the centre of mass is located at 8/2 * 80% = 3.2 feet, then the entire weight of the vehicle would be on the rear wheels on a 80% or 37.5 degree slope.

Hence the OP was suggesting that only RWD would be necessary.

You forgot it was whinched up.......so yes it is a fraud... as most commercials are. Kind regards, Erik-Jan.

Alan Baker writes in article dated Wed, 18 Jan 2006

03:58:44 GMT:

I get arctan(.8)=38.66

Even 4WD with open diffs might do that.

Suppose the wheelbase is 12' and the center of gravity is 2' from the road surface and in the center of the wheelbase.

The 80% grade brings the rear wheels closer to the c.g. -- a ratio of (6-2*.8)/(6+2*.8), which still leaves 37% of the weight on the front wheels and therefore 37% of the potential traction.

The answer is YES, AWD is still important at that angle, if my guesses about the relative location of the center of gravity are right.

-- spud_demon -at- thundermaker.net The above may not (yet) represent the opinions of my employer.

Erik-Jan, Actually, it had a safety line attached in case it did slip and fall off the ramp. Similar to that used by mountain climbers - it's slack, but there as a precaution. If it's the same as the commercial for the 1987-vintage Audi

100/5000 quattro, then you'll see the tether in the film below the centreline of the car. It was not winched up, though, it drove up: the spiked tires.....that's grip, baby! Too bad spikes are illegal here in Canada. BTW, the ad with the Audi climbing the Andes in Chile with no rubber on the rims: no spikes there! There are many other films on the Nordic Audi web site (under "Filmer") - there's probably the test that the German TV show did on the different SUV's climbing the ski slope. Of course, they're essentially commercials, caricaturing the selling points of the vehicle (hence, the use of spiked tires). In my work I've driven my quattro-equipped sedan off-road (in fields and various construction sites), but I'd never drive off-road like the guy in our office that owns a Jeep. Of course, some say the difference between 2 wheel drive and 4 wheel drive is the distance you drive in before you're stuck.....and it holds true for our Jeep guy, who needed an excavator to drag him out this past summer. ;-) Cheers! Steve Sears 1987 Audi 5kTQ - never tried to climb a ski jump, no spiked tires, though 1980 Audi 5k - could negotiate the parking lot of the ski resort. 1962 and '64 Auto Union DKW Junior deLuxes - 36 Hp - gets stuck contemplating climbing hills (SPAM Blocker NOTE: Remove SHOES to reply)