THSCC Forums

What about cases like this?
These are sections of what I can remember from past events. THSCC #8 on left and TSCC #9 on the right...



I always thought it was OK to take it a bit wide to not lose too much speed, but from my observations from the faster drivers, it looks like tighter is always better

What do you guys think? The car in this case is a miata.

Ram,

Shortest distance (usually a strait line) is not always the best path. Just like in your second picture. Another way of looking at the 2nd picture is one of the cones ( the 4th) is just noice.

In your second picture, if it is the element I am remembering, the 3rd cone was noice, and you had to imagine a cone between 4 and 5 to force me to apex a hair later.

as a novice, you were likely told shortist distance to keep you from going 10-20 ft off of where the apex should be. Once you start learning how your car handles and leave the novice stage, you start learning the quickest way isnt always what appears to be the obvious/shortest way.


as a disclaimer, I will say that it almost 3am, im freazing and cannot think strat or spell.

Ram,

I've only been doing this for a year longer than you, with mixed success. With that said, autocross is a game of inches and thousandths. Shorter distance will nearly, just about every, single time beat out higher exit speed.

A simplified Example over a 60 sec, 5280 ft course:

A given turnaround has a diameter of 100 ft, for a circumference of 314 ft (C=pi x D, and assume pi =3.14), 50% of which is driven, so driven distance is 157 ft.

Car B takes a longer line, adding 8 feet to entry and exit. Turnaround diameter is now 116ft, diameter of turnaround now 364 ft, driven distance is 182ft, 25 feet behind Car A.

Car A exits at 30 mph (44 ft/sec) and car B at 35 mph (51 ft/sec) So, if I'm doing my math right (in my head, after a couple Flying Dog IPAs and Trader Joe's Brandy Beans) car B has to travel for about 4 seconds at 35 mph to pass car A, over a straight section of about 205 ft. (edit: I suspect the reality is that the speed difference is more like 1-3mph, lengthening the overtaking distance, but I'm making a lot of assumptions--sorry) BUT, since Car A and B are identical, Car B has to brake sooner and more harshly to enter the next element adding risk that a cone could get hit, the car could push/spin or otherwise degrade the run. Doublecheck my math, but I think the gist is right.

IMO, there needs to be some serious driving talent to make up for that 25 foot deficit (roughly 0.3 secs assuming an average uniform on-course speed of 60 mph, or 88 ft/sec). You've made your 5280 ft course now 5305 ft, and need to maintain an average speed of 60.3 mph to make up the lost distance, even faster to overtake and win. If you're driving at the vehicle's grip limit for the other elements of the course, you will have put yourself in a position that requires you to risk too much to have benefited from the extra speed in that single turnaround situation

There is an exception situation, though, that immediately comes to mind. When your turnaround is followed by a substantially long straight section exit speed may be advantageous to driven distance. BUT, you have to be aware that your end-of-straight speed is higher and must brake earlier or risk upsetting vehicle stability under braking, the inevitable push/cone/spin whatever. I'm sure there are others, but that's the first thing that popped into my head.

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

Steven,

What you are saying sounds correct, however line element 2 if you stick close to all the cones you will get really pinched on the exit. There are also elements where if you dont set up accordingly eg a " thread the needle" where depending on the exit of the previous element, a strait line is not ideal.

I'm on a phone responding, so sorry if I'm not being clear

Don't confuse finding the shortest distance with finding the apex of a turnaround. The two are related, but not identical. Once one has determined where the apex of a turn is, it is then the driver's job to find the fastest way around it, which usually is the shortest distance. Blindly "Hugging the cones" will probably get you in a bad position where the apex is undefined or causes the unwary driver to be in a bad position for the next element. However, the shortest distance around a turnaround of any shape (or slalom, for that matter) will nearly always be the best line (caveat: exceptions do exist, and likely depend on the car's classing, weight/power ratio etc)

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Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

It's a big compromise. In the THSCC #8 example, I doubt you can stay close to all of the cones on the entry half and avoid a big push on the off-camber exit side. You just want to avoid wasting distance side to side or going deeper than the cone at the top the diagram, and still be turned enough (50+%) by the top cone to ensure that you can start accelerating (gently, at first) before you get to the exit gate, and then not have to turn too much more to clear the diabolically placed final cone.

Of course, Stephen W beat me by some meaningless fraction of a second that day, so maybe you should ask him.

Regarding the TSCC #9 example - well, that's just more proof that life's too short to waste your time at Triad autocrosses.

Merry Christmas, Y'all!

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Art McDonald
Premier Amateur #518
2008 Dishman Cup
Pivot Cone Snob

Rodney is a waxer (but in a good way)

Steven, based on the drawings by ram, I believe he was referring to the apex as always being the shortest distance (which is hugging the cones). I agree with you that once you know the apex and the rest of the line, the closet you are to it, the faster you will be. Also 99% of the time, the best line will be get as close as you can to the cones. Thus the novice is often told the straitest line is OFTEN the best line.

Sent from my phone again so sorry if I am not understandable once more.

Arthur, in reference to your razz comment, funny

This is just my approach so please take it with a grain of salt. I always try driving the shortest possible distance, as long as it can be done without pinching myself off or hurting my momentum too much on corner exit. I always find it's easier to get the car to rotate, either under throttle or with a lift, when driving the tighter line. Most importantly, I feel like I can get on the throttle sooner. It just doesn't seem to work as well for me in autocross when driving the wide line. So, I'm a firm believer in the "tight is right" approach. Just my 2 cents.

Eric

How about this example. A semi circular turn around like Steve mentioned but with out cones dictating lines, just and entry and exit gate. Is a constant radius execution better that a 90* turn, straight, 90* turn despite the former being longer distance-wise? I think it would be but my question is why .

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Here's a video from Danville early in the year. You can see Chris (driver #1, white helmet) and Eric (driver #3, black helmet) take the tight line around the big sweeper entering the course. Where I (driver #2, silver helmet), like an idiot, took the wide line. Their exit speeds were similar or even faster than mine, and they drove less distance. On the basis of looking at data at the Extreme School this year, that difference could be huge.

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Karl S.
2014 Baby, 2014 House, 2013 Ford Focus ST, 2013 BMW 328i, 1994 Mercedes E320
(Insert passive aggressive signature line here)

Thanks for all your replies. Toward the end of the year, I got a chance to compare wide vs tight in a few events and noticed that tighter was always faster for me. I started this thread to confirm my findings, as I had trouble believing it myself.

Jason, your thoughts were consistent with mine, but I noticed I started posting better times when I just stuck close to the cones whenever in doubt. I think our miatas have the advantage of being able to turn really well, without losing speed.

Steve, your math was exactly what I was looking for! That extra few mph doesn't seem worth it, unless the followed by a long straight. Thanks

Dustin co-drove my car on THSCC #8. I went first, took the turn wide, ignoring what I thought was a noise cone. Dustin went next, and took it ridiculously tight. I noticed that my car (in the hands of a good driver like Dustin) can handle that "pinch" very well, without loosing too much momentum. So, I tried to take it tight and ended up being much faster.

At TSCC #9 I was absolutely 100% sure that taking it wide and not losing speed was the way to go. During one of my fun runs, I took it tighter...It felt much much slower, but gained almost half a second!

Granted, one of my biggest weaknesses is not staying tight. So, my execution of a wider constant radius line is probably too wide than it need to be.

So, I think next season, I'm going to try to stay as tight as possible (within reason).

I once heard or read a very well decorated, national championship caliber autocrosser make the case that, if you're uncertain, "assume tight is right." I think it was Sam Strano or Andy Hollis.

It can be a tough thing to actually execute on, at least, it is for me. Four years (!!) after I became more serious about autocrossing, I still find myself falling into old "road racy" habits. Bigger radii mean bigger exit speeds, right? Sure! But that's not always the best play when there's an eleventy cone slalom immediately after. You don't always get to leverage big exit speed like you can on a big track.

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Karl S.
2014 Baby, 2014 House, 2013 Ford Focus ST, 2013 BMW 328i, 1994 Mercedes E320
(Insert passive aggressive signature line here)

I learned at VIR that the Miata's suspension compresses way much more than you would initially think. This translates smoothly to autox because it is one less variable to consider when considering situations like this.

Even though "tight is right" most of the time, don't give up late apexes. Another umpteen time National Champ (John Ames) was quoted saying "late apex as early as possible". One of the schools used a phrase "be on the backside of the cone" or something similar.

Also, at dirty sites the "right line" is the "clean" or "popular" line if you run late in the day.

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Dick Rasmussen

FS 50 2018 Mustang GT

This is a critical point to drive home I think. Adding some flavor to it -- figure out what the key cones are and ignore all the others by creating a mental image of the line you will take to ideally apex the turn using only the key cone or cones.

One problem many have, myself included over the years, is that it is actually easier to drive a faster line near that line's limit. As speeds drop, it becomes harder for most to accurately put the car on the limit of adhesion and not over-drive it. At slow speeds with a lot of steering lock needed, any over-driving the front tires is a disaster, but many people get caught trying too hard the slower the corner due to lack of patience. Hence, tight is right, don't overdrive, practice putting the car on the limits in very slow corners, etc.

This is why turnaround cones are so much fun imo, especially if said pivot cone has a very high speed entry to it. It is actually very difficult to bring a car down from say 60mph to 10mph, the last 25mph trail-braking heavily to setup a back-side-the-pivot-cone exit of the turnaround, and not overdrive the front tires of course. Managing braking properly, not waiting too late, and the trailbraking end of the braking zone all as speeds approach walking speed is actually awfully tough to do. When done "just right" it is actually a great feeling as you don't leave the element thinking you just "went real slow" but instead know you just conquered a really hard element and did it just right.

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