Autocross track layout that loops back on itself

[crossthreaded]

Last weekend, the Orange County group did this. It was a blast! Excuse the crude drawing I made in paint, but you get the basic idea. It was at the very beginning of the course (the green dot represents the green flag), so the flag man didn’t start the next car until the previous car was well past this loop.

When they made the track, the outside of the loop didn’t have any cones. There were only cones around the inner circle. You got to choose how wide to take the loop. I put a line around the outer circle in my drawing for clarity. You could choose to have cones there or not.

Also, the track went in the clockwise direction, so this served as a good way to get those outside tires good and warmed up!

I’d like to see the SDR group do this!

[crossthreaded]

I just came across this video of a lap. You can see the loop here:

http://video.google.com/videoplay?docid ... 4383&hl=en

As you can tell, the left turn really start before the loop begins and continues well after the crossover point. So it's more than a 360 degree corner, it's more like 540 degrees!

[Tawfik]

I did like that as well however considering how different the surface is in El Toro and at the Q, I think that having such a loop in SD would cause very uneven tire wear.

[Gary Burch]

Gary Samad is going to be so happy...

[martinreinhardt]

We tried the loop design a few years back. It was an interesting idea but, it wasn't a favorite for many people. It really wears everything the wrong way (tires and transmission).

[ajackson]

Did the loop make the track any more confusing? One of the things I like most about SDR AX tracks is that they are so well defined. I love having a row of cones along both sides of the entire track (minus slolams). If you get lost at any of our tracks, you have to go through a cone wall to do so.

[Tawfik]

Wasn t confusing at all but the tires on the right side weren t happy.

[hmeeder]

I ran with OCR Sunday as well and I would have to say that the skidpad was one of the primary reasons the day ran so long. The loop is deceiving and while the cars are passing around the loop, the starter is holding back. He'd let a car go and 10 seconds later the thing was still only 30 feet away. This causes the starter to wait until the car is a good bit further down the track before letting the next car go. The car would only be 100 feet away, but had already traversed 300 feet of track, if you get my meaning.

For OCR to be able to run 140 drivers 12 times through their 1.1 mile course, they needed to have 8 cars on the course at all times. They rarely ever had more than 5. IMHO the loop is partly to blame for that. I seem to remember we had the same problem when we ran a loop about 2 years ago in the SE lot. That day ran long as well.

A lot of the elements of a skidpad (understeer and throttle control challenges) can be recreated without the gimmick of a loop.

my $.02

[ttweed]

I seem to remember we had the same problem when we ran a loop about 2 years ago in the SE lot. That day ran long as well.

That was exactly how I remember the PCA-SDR "Samad-loop" design. The number of autox runs you can get in a given event duration is totally dependent on the interval at which you send out cars, not the course length. If the loop causes you to send cars at 30 second intervals instead of 20 second intervals, you will get 50% fewer runs in. I think that was the main complaint when we tried it. The starter could not send the next car until the preceeding one cleared the loop. Putting the loop as close as possible to the start will help, but if it takes more than 15-20 seconds for a car to clear it, you will slow the event down and get fewer total runs in.

If there were 140 cars that wanted to get in 12 runs each in 9 hours, that's 1680 total runs for the day. A 20-second interval (with no breaks or red flags at all during the day) will yield 1620 runs in 9 hours. A 30-second interval only yields 1080.

TT

[vntgspd]

Ironically, the loop was requested for the sole purpose of regulating the start time! The loop did not require more than 15-20 seconds to clear which is about the minimum gap you'd want to see on a 1 mile course with tight and open sections. So, if done correctly, a car was to be released as the previous car was exiting the loop, not 5-10 seconds afterward. Unfortunately, several times the starters were chatting with drivers resulting in unnecessary delays. Steve E. promisses a "shock collar" will cure this issue.

I think this element is a fun thing to throw in periodically, but not every time. It's also an excellent teaching tool for instructors. I don't agree that it causes additional tire wear unless you are really overdriving it. If that's the case, you are probably overdriving the rest of the course elements too so tire management is out the window anyway! I also don't think transmission wear comes into play either as the G-loads are relatively low at this point and acceleration/deceleration loads are also minimal relative to the rest of the course elements.

All IMHO of course.

[Jad]

There are severl problems as mentioned with the loop. If it is a reasonable size loop, it should be taken in 1st gear in newer cars ~30-40 mph which is VERY hard on the car, the outside edges of the tires and any low oil areas as the g-loads are sustained for a significant time.

They also offer little in line variation, so skill is minimal, tire grip is the key factor, as holding the inside will be the fastest route. Loops are for NASCAR, not road racing

My vote remains NO on the loop in case the designers are reading this.

[kary]

I agree with Jad (did I say that out loud ). Fastest way around those things is the shortest distance. No skill there.

[vntgspd]

I have no personal stake in the loop idea, but, just to play devils advocate consider:

There is no real skill involved in a 400' straight (especially with all the ABS equipped cars) yet we as autocrossers seem to use them whenever possible and enjoy them to boot!

Also, OCR at least has a lot of newbies and as mentioned before, this is a good tool to teach fundamentals such as tight lines, throttle modulation, looking ahead, and finding the limit of the car.

Personally, I have learned the fundamentals, but do enjoy teaching others. I also enjoy a course where the designer is thinking outside the box and creates something at least unusual if not altogether new. Based on that, I encourage this type of discussion in hopes that we can avoid the cookie cutter sweeper-straightaway-sweeper-lane change courses that sometimes pop up.

Again, just my opinion. Fire away!

[Curt]

Where did all these people come from to have 140 autocrossers in attendance at an OCR event? In the future, you may have to limit attendance to try and keep the riff-raff out. By riff-raff, I mean non-911 drivers.

[Tawfik]

This event allowed both PCA and SCCA.
I personnally didn t mind the number of participants it as we got to compare times with other cars (Vettes, STIs, EVOs, ELise, etc....)