Course Design Feedback & Discussion - FSAE Lincoln

[raitinger]

Originally posted by mdavis:

I didn't drive autocross but I did walk both the initial course and the modified one. I was rather disappointed that the track was moved out of the ~1" dropoff and onto the smooth section of track. A lot of teams run as little ground clearance as possible, but they need to get over it if the track has some bumps. Also the teams running super spindly a-arms are probably not going to like the bumps, but it's a simple matter of not building your car for the super smooth glass sheets that the course can be.

As for your question about using the course maps, we discussed it on the 12 hour drive from Cincinnati to Lincoln, spending time looking over the map, discussing how we would drive it, which ones are the important cones, etc. Unfortunately, we were quite wrong in our initial assumptions, and the extra time to walk the course on Wednesday was massively helpful.

-Matt

PS, that course design handbook was extremely interesting to read. It could be quite helpful for setting up courses in the future for our team.

Matt,

We changed the AutoX course this year and last year due to one of these concrete seam bumps. Last year we had a rather substantial 1.25"+ step input style bump near the end of a max length rules legal straight. The bump ran diagonal to the driving line and would have probably been in some peoples braking zone. This year, as you know, we had .75"-1" bump at about the midpoint of a medium sized 180deg sweeper.

In both instances the course was moved about 15' feet to the side to avoid the bumps. This was more based on our designed intentions for the course rather than to appease people's complaints. You see there are quite a few concrete squares out there and the courses are designed at home on the computer without knowing where all the nasty bumps are. It also goes along with our thought process from my previous post to Charles, we try to give you guys the best course we can put together. We have 60 acres of concrete, if all we have to do get rid of a bump and make the course better is shift it 15' to the side, why on earth wouldn't you do it? Would we just be lazy?

On an also rather important note, we have a nice site and we'd like to keep it. Placing the course over bumps that we believe might incite contact and potentially damage the site is in no ones best interest. I don't think this years bump would have caused any ground contact, just a lot of unsettling mid corner.

Lawrence

[Charles Kaneb]

Originally posted by raitinger:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Charles Kaneb:

That is EXACTLY what I wanted - a bunch of broken undertrays and parts ripped off cars with inadequate ground clearance.

Lincoln has enough perfect concrete to be able to design a nearly glass-smooth autox course. It is a lot smoother than our test site. It is a lot smoother than most teams' test sites. If you don't want teams running considerably stronger ground-effect aero that hasn't been tested under similar conditions to the competition conditions, then you should use the bumpy parts as well as the smooth ones.

Otherwise you're going to see a car that has never pulled more than 2.5g in testing (with 1" of ground clearance) to pull 3+g for the very first time at competition with 1/4" of ground clearance. Between the additional downforce and the very abrasive and sticky Lincoln surface some car whose team has a smart aero guy will be way beyond its test conditions.

Charles,

I can feel the hate for aero cars is strong in you, but I think you are being a bit optimistic about all of the broken parts induced by a 1" bump. If anything I'd guess most of the parts that would break are suspension related. We address what we might see a potential issues in Tech, Grid, and on course. I spoke to several teams personally about various ground clearance issues. Only one team was going to actually get DQ'd for very consistently contacting the track, but they broke down before they were pulled from endurance.

Plus, why would you really want other teams' cars to break so badly. So, you can sit back and manically laugh as your plan to run a rather high ride height has finally become a success. EVERY car should be at the lowest ride height that you can get away with, aero or non aero.

It's my goal for teams to come to Lincoln and get the best performance out of their car as possible, period, especially regardless of their at home test conditions. Every team pays a decent chunk to enter the competition, and we should try to get you your money's worth. I have no interest in trying to penalize teams for exploring a perfectly viable design option such as ground effect aero.

I'd say a special congrats are in order for Auburn, for showing everyone you can still be good without ANY aero, even at Lincoln. There will always be a place in FSAE for simple. </div></BLOCKQUOTE>

Mr. Raitinger, I wasn't THAT serious about wanting to see broken parts! I know what it feels like to have an unexpected problem screw up competition. The team I'm on brought an aero car to Lincoln this year and it worked fairly well.

My point was that allowing lower ride heights than in testing will allow aero teams to achieve significantly more downforce than they had in testing. Between that and the high-grip surface at Lincoln teams will attain significantly more grip than they had in testing. We left the DAQ off, for cost event points, so I don't have a peak or sustained lateral acceleration measurement for you, but I can say that we had to stiffen our springs by about 35% from our surface at home to avoid bottoming out.

I think most of the teams that'll be able to build a car that can pull 3+g on that surface next year will be the ones who generated their load cases around being able to generate that sort of lateral grip and did the right sort of analyses on them. On the other hand, if something's going to break from a one-time overload, it's most likely to do it now in the fastest corner on a course this smooth and grippy, since the ratio of lateral acceleration in fast corners to lateral acceleration in slow corners is going to continue to rise. If we have to anticipate a couple of fairly large bumps it'll let us operate closer to our test conditions.

[raitinger]

Originally posted by Z:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Claude Rouelle:

I even think that this hairpin should preceded and followed by 2 relatively long straights so that we can appreciate the cars both braking and acceleration strengths.[/b]

Claude,

I agree with you 100% on this point!
~~~o0o~~~

Originally posted by Claude Rouelle:
2. This is not Baja but I wish there could be some relatively high speed portions of the track that could be bumpier than what we usually see. That would show which car have <STRIKE>decent damping and</STRIKE> the best possible tire contact patch consistency.

(My edit.)

Claude,

On this particular point I agree with you 1,000% !!! (Err, if that is possible , and except that UWA style soft twist-mode suspension is a bigger advantage than damper rates. )
~~~o0o~~~

Lawrence,

Here is a link to one of my rambles on the "Bump Map". That map might help you decide on suitable heights and lengths of any bumps that you add to the tracks. Ie., hills don't make the suspension work, but bumps about 1 to 2 inches high by 2 to 20 feet long will.

One possible option for "temporary" bumps would be large, moulded rubber mats that are (weakly) glued to the concrete at critical points of the track. Think giant cow pats, say, 10 feet across and 2+ inches high at middle, tapering to 1/4" at edge, that are scattered around corner entries, exits, etc. Bad suspension cars have to drive the long way around, while good suspension cars take the shortest route.

Z </div></BLOCKQUOTE>

Z,

We are definitely going to strongly look the straight-hairpin-straight for next year at Lincoln. The challenge for AutoX is that the entire series of elements will take up a sizable length of the track and have high enough speeds to potentially pull up the avg course speed quite a bit. There may have to be rather slow elements for the entry to first straight and exit of the last. Maybe even end up having a bit of a mountain switchback kinda feel, that actually sounds pretty sweet! The challenge for endurance would be primarily safety. The tight radius of the hairpin brings the entry exit traffic a little too close for comfort, not to mention, the braking/turning/spinning into the hairpin is just asking a pileup accident. However, it would be the ultimate test of your braking system, a more accurate assessment of corner exit coupled outright acceleration, and a less suspension/aero based more powertrain based evaluation of fuel efficiency.

On the subject of rubber cow pats, cow patties here is KS, I would tend to shy away from that approach for multiple reasons. Mainly due to what Claude eluded to with the, this isn't baja, comment. The rules don't remotely discuss added in bumps to any courses. Also, there's the implementation. Weakly glued isn't really isn't much of an option. It would have to be confidently secured for the duration of the event, and then easily removed. We are allowed to bolt-in to the concrete, but bolting in several bumps at potentially different locations each year is probably not good stewardship of the site.

Now, a philosophy of having bumps on course to see who has done the suspensions design exercise the best and filter the ranks of top teams is one thing. As someone said in the suspension thread ,I don't remember if it was you Z or not, but teams can do quite well with virtually no suspension at all. Hence FSAE's place on the bump map next to karts and those oh so competitive indoor forklifts. Adding or insuring bumps on course to keep the idea that you need to "design" a suspension alive is something else entirely, and is something I could support. Two inches of theoretical suspension travel doesn't mean the car won't act an awful lot like a kart. Without hijacking my own thread, this isn't to say that suspensions that have kart like tendencies are not the result of a well sorted suspension design given most FSAE conditions.

The FS Germay video Tobias referenced here is about as good as your going to get in FSAE without purposely adding manufactured bumps. Tobias also makes a great observation which notes the cars that show visible "unhealthy" suspension traits do not appear to sacrifice any time. So continues this circle shaped semantic argument on the focus of this competition and perceived acceptable design solutions, better served by another thread.

I did stumble upon the ideal product for this situation, with a name like Road Quake, you know it's good. Road Quake!!

Side note: Tobi, you and your organizers coverage of FSG is really awesome, keep up the good work!!

[Charles Kaneb]

If you design a straightaway-hairpin-straightaway section, you do not have to make the straightaways all that long - if you make the hairpin less than 180 degrees.

If you need 80' of separation between the exits of the corners leading into and leading out of the hairpin section, and you have a 150 degree hairpin, then if the hairpin is 30' or so wide, you can have two 100' straightaways (100' sin 30 = 50').

Two of these back-to-back would be a nice element to add.

[raitinger]

Nick, a man of many competitions.

Yes, yes, quite the can of worms.

The old reused AutoX course method. I've never accounted for all of the driver potential here for inexperienced drivers to get a better feel for the course along with getting the most out of their cars. Especially if we were to copy the course design into the practice course. I don't know how out of hand it might get, but I it would certainly bring some added incentive to have your car sorted out and through tech earlier. Which I would only guess would lead teams doing better for the rest of the dynamic events. Unfortunately, the two courses, AutoX/Enudrance, would need to be somewhat different to accommodate a variation in speed more or less spec'd by the rules and addition of the passing zones for endurance.

The straight-hairpin-straight, seems to be quite loved by everyone involved, so we will certainly look at adding one in. As I mentioned in an earlier post the hairpin is one of those elements that would be acceptable and easy to do for AutoX, yet would be a safety concern in Endurance. This would be the downfall of the shared AutoX/Endurance course, you'd probably have to limit yourself to course elements that are acceptable for both events.

You are right on the bump situation, we have them, we could put them in. We could really use a "surveyed" bump map to identify where they are and their severity. Anyone volunteering?

We won't allow the leather Aussie hat crew to become too demanding, but I think they can certainly bring something to the table. It also seems the students would enjoy seeing the differences in handling put directly on display.

I'd agree that a several corners are aggressively limiting on corner exits. I can tell the primary reason for this is to limit the turning radius and in turn speed, all in a effort to hit the rule spec avg speeds.

Lawrence

[mdavis]

Originally posted by raitinger:
Matt,

We changed the AutoX course this year and last year due to one of these concrete seam bumps. Last year we had a rather substantial 1.25"+ step input style bump near the end of a max length rules legal straight. The bump ran diagonal to the driving line and would have probably been in some peoples braking zone. This year, as you know, we had .75"-1" bump at about the midpoint of a medium sized 180deg sweeper.

In both instances the course was moved about 15' feet to the side to avoid the bumps. This was more based on our designed intentions for the course rather than to appease people's complaints. You see there are quite a few concrete squares out there and the courses are designed at home on the computer without knowing where all the nasty bumps are. It also goes along with our thought process from my previous post to Charles, we try to give you guys the best course we can put together. We have 60 acres of concrete, if all we have to do get rid of a bump and make the course better is shift it 15' to the side, why on earth wouldn't you do it? Would we just be lazy?

On an also rather important note, we have a nice site and we'd like to keep it. Placing the course over bumps that we believe might incite contact and potentially damage the site is in no ones best interest. I don't think this years bump would have caused any ground contact, just a lot of unsettling mid corner.

Lawrence

Lawrence,

You guys are completely justified in changing the course, and I understand your reasoning completely. A ~1.25" step input would break a lot of cars, especially if there are cars still on the brakes at that point. And I agree completely about not wanting to damage the site. The Lincoln location is fantastic (so much concrete it's not even funny), and doing everything to keep that site is absolutely a good idea.

The thing that I really liked about the endurance course was the left hand sweeper (series of 2 corners that pretty well seemed like a sweeper from the driver change area) where there was a set of bleachers last year (myself and another guy from our team drove out to spectate on Endurance day last year) where there were no bleachers this year. Since I was in the driver change area for our team during endurance, I was able to see the cars there, but that was definitely a showcase corner, in my opinion. Other than that (I watched the last handful of cars from the bleachers), the right hand sweeping corner before the checkered flag station and the slalom right in front of the bleachers were awesome. As a suspension guy, I love watching the cars through quick transition type elements (like the slalom) as well as being able to see the cars in a more steady state corner (the right hander, and even the left coming out of the slalom onto the straight/passing zone). Going back to the big left hander, I really liked that there was a nice patch of sealant/small (~1/2") bump towards the middle of that corner that worked to unsettle the cars. You can definitely see it from our onboard video, and I could see it while watching from the driver change area. If you can find more bumps like that and incorporate them into the different sections of corners, that would be awesome. I know it is one of the things that I would look for on course walks while making the maps for our drivers (the Canada competition had no course maps whatsoever, so even a hand drawn map was better than nothing). I understand it would take a lot of work (there's a lot of concrete to cover to find bumps of all different input sizes, etc. but you could probably cover a lot of it during events like Spring Nationals and Nationals in the fall) but I'm sure you could get some volunteers (I would, but I'll be all out of vacation time this fall).

If you look at the video of the top 5 from FSG last year, at the 9 minute mark, there is a very nice decently high speed transition element that would be really nice to see added to the course. They're a lot of fun to drive, and if there's a big enough time penalty (enough entrance/exit cones) for over cooking it, you should limit the number of drivers pushing beyond the limit of their cars and themselves. This information could be quite useful to design judges (if in the autocross course, and therefore before design finals) or to other team members. It's also fun to see how well other teams cars are working.

Edit: I forgot to say, I like the way the courses are set up in the US a lot better than those in Europe. The fewer cones the better, imo. Our local SCCA region has started removing extra cones from the tracks and it helps a lot. Much less sea of cones, especially when the tops of cones are at eye level.

-Matt

[Claude Rouelle]

A few additional comments

1. About bump(s). I believe that is not the height or the length of ONE bump which will makes us see good car ride or the suspension and chassis elements reliability (our goal is not to make a breaking car circuit; again this is not Baja); it is the frequency of several bumps in a row in the car heave and pitch natural frequency region that will make noticeable difference.

2. We need 1 or 2 270 degrees constant radius but also 1 or 2 270 degrees decreasing and increasing radius followed by a corner turning the opposite way. A tight left hand corner after a increasing radius right hand and a fast left hand corner after a decreasing right hand corner is a good idea. That is the best way to see the car handling in constantly changing lateral AND longitudinal accelerations.
Some sacrifices in the usual theoretical trajectory will have to be made but that is where you will see if drivers are able to make good decisions ("wrong" entry for the benefit of a "good" exit or vice versa), and if good car can react to such driver input.
The difference in good and not so good cars lap time will definitely be bigger.

My other 0.02 $ advice.

[Edward M. Kasprzak]

VIR was mentioned earlier in this thread. While the elevation changes and camber were a plus, I don't think it had much else going for it (other than being very scenic!). The narrow racing surface left few options for course setup -- just about the whole course was slaloms and chicanes. Imagine trying to setup a course someplace even narrower than Michigan, with no possibility of any tight turns (no 90s, no hairpins). The sprawling track was also inconvenient for track marshalls, cone chasers and spectators, in part because a grove of trees was located in the middle of the circuit!

I like some of the ideas discussed in this thread. I don't think artificial bumps are necessary, and some suggesting a 1 inch bump may be assuming the car will be at static ride height while on the track (not true!). Increasing radius, decreasing radius, one-cone hairpin, a hard braking zone, increasing/decreasing slaloms, linked corners, etc. are all good.

Whatever future layouts are chosen, I hope rules D7.2.4 and D8.6.3 are not invoked too often. If it's looking like they will, I suggest a discussion with the Rules Committee.

[Edward M. Kasprzak]

If I can dream for a minute: Given the oval racing heritage in North America, and all the interesting vehicle dynamics that come with asymmetry, I'd love to see an "oval" event at Michigan or Lincoln. Two 180s just a little bigger than the skidpad radius connected by two straights (make the straights so that half the track length is cornering, half straights). Give each driver four or five laps and count the best lap. 50 points skidpad, 50 points acceleration, maybe 75 points "oval" and reduce the autocross points to keep the total at 1000. Oval and autocross could run at the same time, just as skidpad and accel do now. I know MIS doesn't really have the room to do this without getting creative, but Lincoln could.

[/dream off]

[raitinger]

Originally posted by Charles Kaneb:



Mr. Raitinger, I wasn't THAT serious about wanting to see broken parts! I know what it feels like to have an unexpected problem screw up competition. The team I'm on brought an aero car to Lincoln this year and it worked fairly well.

My point was that allowing lower ride heights than in testing will allow aero teams to achieve significantly more downforce than they had in testing. Between that and the high-grip surface at Lincoln teams will attain significantly more grip than they had in testing. We left the DAQ off, for cost event points, so I don't have a peak or sustained lateral acceleration measurement for you, but I can say that we had to stiffen our springs by about 35% from our surface at home to avoid bottoming out.

I think most of the teams that'll be able to build a car that can pull 3+g on that surface next year will be the ones who generated their load cases around being able to generate that sort of lateral grip and did the right sort of analyses on them. On the other hand, if something's going to break from a one-time overload, it's most likely to do it now in the fastest corner on a course this smooth and grippy, since the ratio of lateral acceleration in fast corners to lateral acceleration in slow corners is going to continue to rise. If we have to anticipate a couple of fairly large bumps it'll let us operate closer to our test conditions.

Charles,

I understand your point a little more clearly now as a safety/reliability concern. I'd say teams are already in this boat of coming to Lincoln and experiencing higher accelerations than their test site. As you mentioned your team had to up the spring rate, I've heard of other teams having part failures right out of the box when they show up to Lincoln on parts which already have some solid testing hours completed.

Unfortunately or fortunately, depending on how you look at it, I think this is more a product of the very "grippy" concrete surface rather than any huge advantages in ground effect aero. No one is going to get away with a 1/4" ride height. If you watch some driving videos from Lincoln you'll see there are enough bumps to keep that from happening, unless MAYBE it's an unsprung set-up. In this respect the playing field is leveled a bit.

I suppose we should let it be know, if you plan on coming to Lincoln, expect a higher coeff of friction and in-turn higher accelerations.

You're right on the necessary lengths of the the straights for the hairpin. You'd preferably want the entry straight to be longest and the exit to be long enough to ensure the opportunity for cars to show their maximum corner exiting ability. Yes all of the packaging becomes easier the farther you get from a 180 deg hairpin.

Lawrence