Tighter Turn-around at Brookville?

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Tighter Turn-around at Brookville?

Postby bluesight » Mon Jan 02, 2017 8:48 pm

You've probably been through this before, but I've been fooling around with alternatives to the "skid pad" style turn around at the top end of the Brooksville courses. I can't seem to get it down right, and it's tough on my tires. I drew up a "low speed" option...

B
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FAST Open Autocross - Jan 14 @ Brooksville

Postby Jamie » Mon Jan 02, 2017 10:07 pm

bluesight wrote:You've probably been through this before, but I've been fooling around with alternatives to the "skid pad" style turn around at the top end of the Brooksville courses. I can't seem to get it down right, and it's tough on my tires. I drew up a "low speed" option...
Not sure how a pin turn makes things easier on tires, unless you make it so tight it's a first gear turn (which is tough on non-CVT transmissions!). Even then it doesn't save much -- we've done this type of turn at smaller sites, like the Tampa Greyhound Track, or further back, St Petersburg College, and unless you're equipped with a limited slip diff, you're nearly guaranteed to have the unloaded tire sanding itself smooth as you accelerate out of the exit.
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FAST Open Autocross - Jan 14 @ Brooksville

Postby bluesight » Mon Jan 02, 2017 10:24 pm

I expected there isn't much that can be done...just a thought as an "outsider". I've been on some Milwaukee courses with pin turns, and it is usually a drag to accelerate out...even with CVTs. Usually they appear as a change of pace more than anything else....

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PS...some examples...Miller Park courses with "tight" turns:
Miller Park 2006_noted.jpg
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Miller Park 2013_noted.jpg
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PPSS...Sorry...I should have posted this in a more general discussion forum. Please move if possible/appropriate...I see it was discussed in 2013 in the Course Discussion forum..'nuf said...
Last edited by bluesight on Mon Jan 02, 2017 11:31 pm, edited 3 times in total.
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FAST Open Autocross - Jan 14 @ Brooksville

Postby Loren » Mon Jan 02, 2017 10:40 pm

Short answer: We try really hard to avoid courses that require a 1st gear downshift.

Longer answer: We have a small site (Tampa Greyhound) that requires tight turns. We do them there. When we're at the airport and don't HAVE to do them, we generally don't. However, you might notice that we DO vary the approach and entry, and the radius of the turn varies from somewhere around 45 feet to a maximum of about 60 feet. (keeps everyone in 2nd gear) It's also varying degrees of difficult to find the proper LINE through the turn. We have fun with it... and on VERY rare occasions, we'll do something close to a "pin turn". But, you won't see it at an Open event. It's not fair to the horsepower-challenged.

Better answer: Read the Course Design Guide a few times. Great info for anyone who wants to design or DRIVE an autocross course.
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FAST Open Autocross - Jan 14 @ Brooksville

Postby JasonS » Tue Jan 03, 2017 1:31 pm

Better answer: Read the Course Design Guide a few times. Great info for anyone who wants to design or DRIVE an autocross course.
Highly informative. Thanks for sharing. :notworthy:
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Tighter Turn-around at Brookville?

Postby Loren » Tue Jan 03, 2017 2:27 pm

Split this into a new topic and put it in the proper place. Wasn't really relevant to the January 14th event, as we've already designed a course for that event.

Mike, you're pointing out 150' Diameter turns on those maps and apparently calling them tight. 150' diameter is the absolute MAXIMUM we could ever do at Brooksville. (and we won't do that because it allows zero run-off on the exit side) Every turn-around we do there is typically a minimum of one block (12.5 feet) from the grass on each side. Meaning that if you drove the absolute WIDEST line that you could (which nobody does), it would be 125' diameter... or about 60' radius. Max speed at .95G on a 60' Radius is about 29 mph. Slower than that is going to make people want to downshift to first gear... which is something we try to avoid.

And that is why you'll rarely see a FAST course with a turn-around any tighter than about 45-50' Radius.

What you WILL find is that we usually make the turn-around "loose" enough that if you miss your mark, you don't have to beat yourself (or your tires) up to avoid hitting a wall of cones or going into the grass. We try to give you enough run-off space to make a mistake without costing you anything but time. You'll also notice that we alternate doing the turn-arounds clockwise and counter-clockwise. Tight or loose, doing that kind of turn 6 times in a row is going to wear the tires on one side of the car. We try to mix it up. We also look at balancing hard left and hard right turns throughout the same course. We've got your back, whether you realize it or not. :)

Let's go back to last weekend's course, which is what started this discussion. Here's the map. Note that the tightest diameter you could drive that turn-around is about 106 feet (the left and right apex cones add up to 3.5 blocks from the grass, 3.5 x 12.5 = about 44 feet). The widest line you could take would be about 131 feet (about 1 block wider on each side). Realistically, most people probably took a tight entry, and went a little wide on the exit, putting them at about 120 foot diameter... assuming they drove it like a skidpad... which is, of course, the HUGE mistake that a lot of people make. They'll drive in hot on the entry, try to yank a tight apex, and turn it into an egg-shape with their tires screaming for mercy all the way through the exit side.

Personally, I think that's the perfect turn-around. It allows your "tight and tidy" driver to make a perfect 106' skidpad turn. Gives plenty of room for error. And requires some skill in course reading AND execution to get right.

Y'all feel free to keep discussing this all you want. But, Mike... please take a moment to consider that saying "I can't figure out how to drive this skidpad turn-around, and it's tough on my tires, so you should make the turn-arounds easier" is absolutely NO different than someone saying "I'm no good at slaloms, and I keep hitting cones that scuff my paint, so you should make the slaloms easier". You're asking for the proverbial "I" course. The course that "I" can drive.

As a course designer, I have to design courses that are fun and fair for everyone. Not saying that we get it right every time, but that is the goal. No great advantage to the high-powered cars. No great advantage to the small-nimble cars. SOME advantage to the experienced autocrosser who can read the course correctly. All without getting too many people lost.
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Tighter Turn-around at Brookville?

Postby Loren » Tue Jan 03, 2017 2:32 pm

JasonS wrote:
Better answer: Read the Course Design Guide a few times. Great info for anyone who wants to design or DRIVE an autocross course.
Highly informative. Thanks for sharing. :notworthy:
It's been shared before, though probably not recently. It is often referred to as "the course design bible". It's really good stuff, and we do our best to follow most of it. Sometimes we get stubborn and do something gratuitous just because we want to. But, our primary focus is to make courses that are safe, flow well, are fun to drive, easy to navigate without getting LOST, but not necessarily easy to drive FAST without some experience and skill. While I design probably 80% of our courses, and draft the maps for all of them, every single course goes through a review of 4 people who are looking for all of those things. And then we almost always pre-drive the course just to be sure it looks and drives the way we expected it to.
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Push Harder - Drive as close to the limit of your tires as possible.
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Tighter Turn-around at Brookville?

Postby Loren » Tue Jan 03, 2017 2:44 pm

bluesight wrote:Usually they appear as a change of pace more than anything else....
Also keep in mind that you're skipping half of the FAST season.

You probably missed this one:
http://drivefast.org/wp/Maps/Brooksville_2016_07_02.pdf

And this one:
http://drivefast.org/wp/Maps/Brooksville_2016_09_24.pdf

And this one:
http://drivefast.org/wp/Maps/Brooksville_2016_11_06.pdf

We change things up quite a bit... well, as much as we can given what we have to work with.
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Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
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Tighter Turn-around at Brookville?

Postby bluesight » Tue Jan 03, 2017 4:01 pm

Looked over the available 2016 course maps. No more whining...the courses all look fun and challenging...and, from (limited) personal experience, they were. Thanks for that! One that intrigues me is the 6/18 Classic that I missed where there is a tightening slalom before the turnaround. I think that's a feature (a slight slowdown prior to entry) I would be interested in driving...

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Tighter Turn-around at Brookville?

Postby Loren » Tue Jan 03, 2017 4:08 pm

Decreasing slaloms are one of my favorite elements to put into a course, but they are VERY tricky, and invariably lead to spins by inexperienced (and a lot of times even experienced) drivers. You'll see one every now and then, but not too often... and usually at a Classic.

Running so many events at an airstrip where courses inevitably include variations of slaloms, and some kind of turn-around. It is, indeed, challenging to make each course seem a little different from the last!
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Tighter Turn-around at Brookville?

Postby twistedwankel » Sun Jan 29, 2017 4:39 pm

I remember Mike saying not too long ago he had trouble with the turn around at Ft Meyers and never seemed to get it right. Maybe Mike is ready for a few laps with Tim at Bradenton. There are no cones and the turn around is "after the finish" and slow :idea: I struggle to get all turn arounds right simply because they require patience to do right and they give me too much time to think about them.

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