FSAE Lincoln 2013

[jcampbe17]

Good luck to all the teams competing at Lincoln this year! For those of you who aren't in attendance but would like live updates on what's going on, follow the Illini Motorsports twitter (@IllinoisFSAE). We will be be giving updates throughout the week, including live updates during the autocross and endurance events!

[Charles Kaneb]

We blew up two trucks going to Lincoln this year.

The California Golden Kart is awesome.

Lots of cars look like they're set up to run a big, fast course, and that's what we have here.

[JayhawkOne]

Does anyone know if there will be a live audio stream for this event? Just because I have to work on Friday doesn't mean I have to be productive http://fsae.com/groupee_common/emoticons/icon_wink.gif

[RANeff]

Hey everyone! The SCCA Nationals Team who are donating their time to help run this years FSAE Lincoln have asked us to post videos of tomorrows Auto-x and Saturdays enduro course. Check them out!

http://youtu.be/-F0IBct4kLU

http://youtu.be/KVgxgvuumdc

[acedeuce802]

Thanks for posting the videos! Has anyone heard about static event scores yet?

[Kirk Feldkamp]

UPDATE! UPDATE! UPDATE! Who looks good this go around?

[SAE_intl_girl]

Originally posted by JayhawkOne:
Does anyone know if there will be a live audio stream for this event? Just because I have to work on Friday doesn't mean I have to be productive http://fsae.com/groupee_common/emoticons/icon_wink.gif

Yes...the SCCA Nationals staff will be providing live both of the following:
a. The sololive.scca.com will display unofficial results without penalties used for all dynamic events only
b. The www.ustream.tv/channel/SCCASolo (http://www.ustream.tv/channel/SCCASolo) is for audio and video. We have been using this for audio in MI and will try to include video for Lincoln of AutoX and Enduro only.

[SAE_intl_girl]

Originally posted by acedeuce802:
Thanks for posting the videos! Has anyone heard about static event scores yet?

Static Scores will be posted tomorrow.

[SAE_intl_girl]

Design Finalist is NO PARTICULAR order for the IC Class:

#1 University of Kansas
#2 University of Texas Arlington
#4 University of Washington
#5 Texas A&M University
#25 University of Oklahoma
#70 Auburn University

Good luck to all the finalists!

[BluSTi]

Pretty happy with how we're doing so far. Track looks fast, braking zones look good, but some of those gaps in the concrete are pretty rough.

[wagemd]

Any word on the Electric Cars?

[TMichaels]

Only 5 EVs showed up.
Unicamp made it through most parts of the technical inspection and just has to pass brake tomorrow.
Michigan-Dearborn will not try to pass EV tech inspection.
Kansas and Washington have been in EV tech today and might be able to pass tomorrow.
Montreal has not been to EV tech inspection so far, but will try to pass tomorrow as well.

All other teams dropped out before the event.

[JayhawkOne]

Originally posted by TMichaels:
Only 5 EVs showed up.
Unicamp made it through most parts of the technical inspection and just has to pass brake tomorrow.
Michigan-Dearborn will not try to pass EV tech inspection.
Kansas and Washington have been in EV tech today and might be able to pass tomorrow.
Montreal has not been to EV tech inspection so far, but will try to pass tomorrow as well.

All other teams dropped out before the event.

That's rough. Hopefully they can get a better showing next year.

[AxelRipper]

Loving the live timing here at work. Though the acceleration is at least a bit screwed up (adding the 2 fastest runs?)

[RobbyObby]

Originally posted by SAE_intl_girl:
We have been using this for audio in MI and will try to include video for Lincoln of AutoX and Enduro only.

Hot diggity! I hope you guys get a video feed up and running. I know my afternoon is wasted if that happens.

Any word on why the timing system is all screwy? They're adding the two fastest accel times and only showing the fastest single skidpad lap. Also there are plenty of teams that show "No Time", us included, even though we ran a 3.95 and should be sitting in 1st in accel.

Also I've heard some teams saying the unofficial design standings have been posted. Anyone know if they've been uploaded to the social medias yet by anyone?

[Nihal]

Robby, see if this works for you. Only one page though.

https://sphotos-a.xx.fbcdn.net...488829_5082624_n.jpg (https://sphotos-a.xx.fbcdn.net/hphotos-ash3/1044295_10151730133488829_5082624_n.jpg)

[RobbyObby]

Originally posted by Nihal:
Robby, see if this works for you. Only one page though.

https://sphotos-a.xx.fbcdn.net...488829_5082624_n.jpg (https://sphotos-a.xx.fbcdn.net/hphotos-ash3/1044295_10151730133488829_5082624_n.jpg)

Nice, that's exactly what I wanted to see! Thanks.

[RobbyObby]

Anyone know why the audio and/or video stream isn't up and running? <STRIKE>Also, the live timing isn't updating at all either.</STRIKE>

EDIT: NVM, Live timing is up now.

[SAE_intl_girl]

Saturday's Endurance Run Order list can be found online at:
http://students.sae.org/competitions/formulaseries/

**Autocross scores will be posted onsite first thing in the morning ;-)

[JayhawkOne]

Originally posted by SAE_intl_girl:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JayhawkOne:
Does anyone know if there will be a live audio stream for this event? Just because I have to work on Friday doesn't mean I have to be productive http://fsae.com/groupee_common/emoticons/icon_wink.gif

Yes...the SCCA Nationals staff will be providing live both of the following:
a. The sololive.scca.com will display unofficial results without penalties used for all dynamic events only
b. The www.ustream.tv/channel/SCCASolo (http://www.ustream.tv/channel/SCCASolo) is for audio and video. We have been using this for audio in MI and will try to include video for Lincoln of AutoX and Enduro only. </div></BLOCKQUOTE>

I was looking forward to the video feed, any updates?

[Nihal]

Anyone been able to get at least the audio feed working?

[nick roberts]

Try this one:

Endurance stream (http://www.ustream.tv/channel/fsae-2013-endurance)

[PeterK]

Congrats to UVic for finishing endurance!

[RobbyObby]

Anyone know what happened to San Jose State??? The announcer on the live feed didn't mention a thing!

[TMichaels]

IC Overall:
1st: Uni of Washington
2nd: Auburn Uni
3rd: Missouri S&T
4th: Kansas

EV Overall:
1st: Unicamp eRacing
2nd: Uni of Washington
3rd: Kansas
4th: Montreal
5th: Michigan-Dearborn

Unicamp eRacing was the only team to pass tech completely. I talked a lot to the other EV teams (attending with and without cars) and I think we will see quite some improvements next year.

[whiltebeitel]

Anybody have a picture of the overall results, with the points?

[Z]

Does anyone have any carrier pigeons?????

(Methinks they would work better than this interweb thing...http://fsae.com/groupee_common/emoticons/icon_frown.gif)

Z

[J. Vinella]

Congrats to the University of Washington FSAE Team. It has been a long time coming. Your alumni are all very proud. Great showing!

[Michael Royce]

Patience gentlemen. 24 hours is not going to kill you! Kaley would have been traveling back yesterday (Sunday), and I suspect that she has been allowed the day off to spend with her husband and her young daughter as she will not have seen them for a week.

[SAE_intl_girl]

Thanks Michael for the defense; actually we are still in Lincoln just finishing tearing down the competition site. I should have results in my hand tomorrow when I'm back in the office from our scorekeeper. I will be sure to post them before taking a day to hang with my family ;-)

[mdavis]

I'm not sure why it's upside down, but here's the picture I took on site of the final results:

https://docs.google.com/file/d...amc/edit?usp=sharing (https://docs.google.com/file/d/0B2GEz-mW365RR1g2b0dnRmR6amc/edit?usp=sharing)

[Jack028]

Congrats to all of the teams at FSAE Lincoln.

Huge congrats to the University of North Texas as well. They are a first year team who managed to compete every event including endurance and placed 31st overall. Unfortunately they did not hand out a rookie of the year award this year.

[whiltebeitel]

Thanks, mdavis!

Kaley, I appreciate all your hard work to keep eveyone informed! Someone's got to feed the ravenous alumni!

I'll second the mention of UNT. They came to the Texas SAE Student night and gsoaked up all the advice they could get. They did a great job! Husker Motorsports also did very well in their 2nd year.

Looks like A&M's black flag in endurance was due to a faulty stator.

[SAE_intl_girl]

Results from FSAE Lincoln 2013 can be found online at: http://students.sae.org/competitions/formulaseries/

[wagemd]

Thanks for all the work, we certainly appreciate it! Don't mind Z, he's just antzy.

Are you planning to post Excel versions as well?

[SAE_intl_girl]

Yes they should be posted online tomorrow under the competition results link.

[Screech F50]

First, a huge congratulations to all teams!

Since my first competition in 2010, I've always been confused by design. This year has 18 teams tied for 7th (19 if you don't count the penalty), 12 teams for 26th, 15 teams for 39th. Also this year, I know the judege's initial scores (on the design feedback sheets) of two teams in the same bay had a difference of 19 points, yet they both tied for 7th. I understand there is some normalizing done after all teams are judged in the first round, but if far more than half of the teams will tie over just three places it's difficult to see a proper measure between competitors. Especially if you see two judging sheets from the same bay with different scores get the same number of points for design. There should be a better, more accurate way to do this. Though, admittedly, I don't know what it is. Afterall, this is the heart of this competition (IMO, of course!). I can see two or three teams tying for a position, but 18?? Nope.

[AxelRipper]

Originally posted by Screech F50:
First, a huge congratulations to all teams!

Since my first competition in 2010, I've always been confused by design. This year has 18 teams tied for 7th (19 if you don't count the penalty), 12 teams for 26th, 15 teams for 39th. Also this year, I know the judege's initial scores (on the design feedback sheets) of two teams in the same bay had a difference of 19 points, yet they both tied for 7th. I understand there is some normalizing done after all teams are judged in the first round, but if far more than half of the teams will tie over just three places it's difficult to see a proper measure between competitors. Especially if you see two judging sheets from the same bay with different scores get the same number of points for design. There should be a better, more accurate way to do this. Though, admittedly, I don't know what it is. Afterall, this is the heart of this competition (IMO, of course!). I can see two or three teams tying for a position, but 18?? Nope.

The issue becomes when you try to normalize 100 teams across 150 points. Thats why they do 10 point increments. Without one group of judges weighing in on every vehicle (done in other competitions, but with <20 teams) you aren't able to say "well, these teams knew their stuff about the same amount, but the equation they showed me on their brakes was far more indepth than the amount of engine tuning these guys did. 95 for them, 93 for them." It just doesn't work out well that way.

With the judge bays, from what I understand is they convene and decide on what level a team knew what they were talking about (this is the key to the event). If they blew the judges away with a spectacular understanding (an A+ if you will) then they get put in the semi-finals. If they knew what they were doing on nearly everything and could explain it (an A grade in class) then they get the maximum points (100 or 110) that they can get without that A+ rating.

Really, if you consider it the same as a letter grade with a point value designated to it, it makes a lot more sense.

[Z]

SAE_intl_girl (Kaley),

Thank you for feeding the pigeons. http://fsae.com/groupee_common/emoticons/icon_smile.gif
~~~o0o~~~

I like this car (http://fsae.berkeley.edu/index.php/news/). Does anyone have more information on it, such as engine details (apparently 250cc)???

Z

[Markus]

Not to take away from them, the car looks interesting and I like the use of 8" tires (it's on now http://fsae.com/groupee_common/emoticons/icon_wink.gif) but it seams a bit heavy given the simplified approach?

I would have expected <110kg or 115kg max. I hope they really bring it on with the next car.

For comparison DUT06 was ~120kg with 10" tires and 450cc engine. As far as I know it's the lightest car ever to complete endurance.

[RacingManiac]

275 seems plenty light, considering unlike Delft with its copius amount of composite material, this is fairly conventional in that respect.

[Markus]

DUT06 was not overwhelmed with composites, but yes, it did have a monocoque. Still I'd think 8" + spaceframe would equal 10" + monocoque in terms of weight.

Anyway I think Berkeley was playing it safe for this year, which is a really good call when doing such an unconventional design for the first time. It's no secret that finishing endurace should be the priority, not going straight to extremes.

I'm really looking forward to see their next car, I bet they have a lot in their sleeves. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Francis Gagné]

The engine is a Swissauto 250, usually found in superkarts. It is 35 HP stock and weighs 26kg WET.

I really like the concept, and they managed a 22nd overall place which is good. But it seems to lack competitiveness even though they had lot of track time with it.

I wonder what limited it's performance, is it the tires that are just not up to par or if it's something(s) else on the car.

[MCoach]

From talking to the team it looks like the engine and tires limited the performance of the car. They claimed only 1.1 to 1.2Gs lateral. The car also seemed to have a top speed of about 50 mph. No word on the motor, but they said they were looking into 10" options for next year to see if they can pick up anything there.

[Z]

Francis,

Thanks! This Swissauto250 (http://www.swissauto250.eu/Specifications.htm) does look like the engine in their images. If so, then their performance is all the more admirable, because it is a no-gearbox, centrifugal clutch only driveline.

Also, their 5.8 second best time for Skid-Pad suggests a cornering Gs of slightly under 1.1G. I guess this is down to the relatively hard compound (?) tyres they are using.
~~~o0o~~~

I hope the Cal-Berkeley team continues along this path. Should any of their team members be reading this, here are some suggestions for changes they could make next year (please take these as constructive criticism http://fsae.com/groupee_common/emoticons/icon_smile.gif).

1. Simplify suspension. Double-wishbones at front are tooooo complicated! Using only single spring-dampers front and rear is good, but mount them much lower. In fact, damperless rubber/poly springs (F500 style) are enough.

2. Simplify chassis. Shifting driver backward (say to weight = 40%F:60%R) so feet are just behind front axle line allows simpler chassis (the mandated two roll hoops, front IA, and side-impact tubes are about all that is needed).

3. Maybe stickier 10" tyres at rear. These will suit the greater rear weight% (from above). Handling balance is easily adjusted by other means. Important note: To go fast, chase outright grip first, then handling balance second.

4. Rearward leaning single-cylinder engine is a great fit for this type of concept. If you decide to change the engine, then keep this same layout! Main changes I would consider are lower revs + larger capacity, for easier final drive ratio, and air-cooling via crank mounted fan, for less hassles with radiator.

5. AERO-UNDERTRAY!!!!! Even with the Mu = ~1 tyres you should be able to blow everyone away in Skid-Pad because the car is so light. Good AutoX and Enduro results will follow.

Regardless of above comments, the approach of building a simple car that is finished and tested early, and scores points in all events, is the right one. Keep following that path!

Z

[Charles Kaneb]

I loved seeing the Cal-Berkeley car at competition. It was a major breath of fresh air in a competition where some very complicated, specialized, and expensive equipment has been successful recently.

Z, the very simple and good load paths on the front end made it very easy for a double-a-arm suspension to be built for that car. Anything else would be far more flexible or heavier. The suspension wasn't a problem.

Having said that, the dynamic performance of the car was poor. It's pretty obvious that the tires just don't have anything like the level of grip that is needed to run up front. This is 90+% of why A&M didn't build a very similar car this year. The American Racer tires not only fail to provide an adequate friction coefficient, but they also saturate at a low enough vertical load and wear fast enough that adding downforce might get them nowhere. They also had trouble with a too-narrow powerband - it was either screaming or lugging, and their top speed couldn't have been much more than 60 M.P.H.

If they can get their hands on a really good 8" tire, they'll have a great time developing a very competitive car. Claude has discussed a tire that he says could provide spectacular performance on a car like this. Nobody's been able to find this tire. If it exists, I think OptimumG needs to sell Cal-Berkeley a set of them. B13 was the breakthrough car that we've been waiting for but it just plain won't work without good tires.

[AxelRipper]

Maybe they should try these: http://www.summitracing.com/parts/hoo-18030/overview/

Jr Dragsters and golf carts are the only other applications I've ever found that run 8"rims. So that leaves dragster tires or possibly some lawnmower tires for them.

I figure with some normal pressures in them (not the 3-4 psi in drag racing) they miiight just work. Of course, never had a car with 8" rims to test them. Can be had in 8" or 10" widths.

[Z]

Originally posted by Charles Kaneb:
The American Racer tires not only fail to provide an adequate friction coefficient, but they also saturate at a low enough vertical load and wear fast enough that adding downforce might get them nowhere
Charles,

Your above quote is typical of the disappointing sort of engineering "reasoning" that is all too common in the profession. Typically;
"Oh, no, no, no. That will never work because ... "

Do you really believe that, say, doubling the vertical load on the tyres will NOT increase their lateral force capability at all? Or that the tyres will then suddenly wear out almost immediately?

Here is another example;

[I]"the very simple and good load paths on the front end made it very easy for a double-a-arm suspension to be built for that car. Anything else would be far more flexible or heavier."

Much as I like the overall concept of Cal-Berkeley's car, there are nevertheless many details that can be improved.

The chassis, for one, is poor. Frankly, it is typical of all the FSAE spaceframes I have seen in that it is far too complicated, has terrible load paths, and consequently has more weight and less stiffness than it could/should have. I figure it has about twice as many tubes as are necessary, and probably three times as many nodes (all of which take time to cut and weld).

This is largely the fault of your teachers, but clearly the notion that "we just have to give them the CAD/FEA tools, and they will discover how to design optimal structures" has been a complete and utter failure.

Anyway, the car is a good start in the right direction, but there is still a long way to go. Good time now for a thorough, and very critical, design review.

Z

(PS. I would be looking at Quad-Bike/ATV dirt racing tyres for alternate 8"s.)

[MCoach]

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 Charles Kaneb:
The American Racer tires not only fail to provide an adequate friction coefficient, but they also saturate at a low enough vertical load and wear fast enough that adding downforce might get them nowhere
Charles,

Your above quote is typical of the disappointing sort of engineering "reasoning" that is all too common in the profession. Typically;
"Oh, no, no, no. That will never work because [insert any technical sounding reason here, regardless of how nonsensical] ... "

Do you really believe that, say, doubling the vertical load on the tyres will NOT increase their lateral force capability at all? Or that the tyres will then suddenly wear out almost immediately?
</div></BLOCKQUOTE>

What is the disappointing logic here? These tires don't have a high enough friction and there are other options that are very viable.



The chassis, for one, is poor. Frankly, it is typical of all the FSAE spaceframes I have seen in that it is far too complicated, has terrible load paths, and consequently has more weight and less stiffness than it could/should have. I figure it has about twice as many tubes as are necessary, and probably three times as many nodes (all of which take time to cut and weld).


Then build your own.



(PS. I would be looking at Quad-Bike/ATV dirt racing tyres for alternate 8"s.)

Already have. As Alex pointed out, we've even looked at lawn mowers.

[Goody]

Originally posted by Jack028:
Congrats to all of the teams at FSAE Lincoln.

Huge congrats to the University of North Texas as well. They are a first year team who managed to compete every event including endurance and placed 31st overall. Unfortunately they did not hand out a rookie of the year award this year.


Originally posted by whiltebeitel:
Thanks, mdavis!

Kaley, I appreciate all your hard work to keep eveyone informed! Someone's got to feed the ravenous alumni!

I'll second the mention of UNT. They came to the Texas SAE Student night and gsoaked up all the advice they could get. They did a great job! Husker Motorsports also did very well in their 2nd year.

Looks like A&M's black flag in endurance was due to a faulty stator.


Thank you for mentioning us. We are very proud of our 31st place finish, our University didn't have an FSAE program this time last year. We had just started the process and were able to compete in all of the events.

We'll see you next year!

-Mike
UNT - Mean Green Racing

[slicktop]

Originally posted by Z:
Much as I like the overall concept of Cal-Berkeley's car, there are nevertheless many details that can be improved.

The chassis, for one, is poor. Frankly, it is typical of all the FSAE spaceframes I have seen in that it is far too complicated, has terrible load paths, and consequently has more weight and less stiffness than it could/should have. I figure it has about twice as many tubes as are necessary, and probably three times as many nodes (all of which take time to cut and weld).



I was wondering if you could be a little more specific about what it is that you find to be poor design in Cal-Berkeley's spaceframe (or any other team's chassis for that matter), particularly in regards to the load paths and excess tubes. There's a nice picture of their chassis in the link on page two.

[BluSTi]

Ok, fun times were had, but I have two gripes, well, three.

1. The faster cars in the autocross should run first in the endurance. If they're going to make any attempt to "normalize" scores, then the faster autocross cars should drive on a clean track and the slower cars should get a track that has already been rubbered in. The way it works now, The slower cars are slow, and the faster cars are doubly (no not doubly, but you get my point) faster because there's more rubber on the track.

2. The cost report is a complete sham. This convoluted process of costing is a joke. Aside from flat-out lying on your cost report, the costs involved are absurd. Here's another idea, provide a MSRP for everything. If you don't have the MSRP, say, for a sponsored part, then a copy of whatever value your sponsor is claiming for their tax deduction. This way, the parts and their associated costs are all searchable and verifiable. Additionally, it removes the "sweetheart deals" that some teams are using.

3. Where were the recruiters? Maybe they hung out at UW the whole time, but in Fontana they were aggressive and numerous. This competition isn't about building a race car, and it isn't about a learning process. This competition is really about getting jobs. Specifically, getting jobs in the motorsport industry. I was really disappointed in the lack of recruiters I saw this year.

4. (I lied about there being 3 gripes, sue me.) If we finished 24th in the enduro, and there were 27 teams that finished overall, I feel that we shouldn't have gotten 30th. Yeah, I know why, with points etc, but there are three teams that didn't finish the race that beat us? How does that logic work? There should be either a penalty for not finishing, or a bonus for completion, but the last time I checked, you can't win if you don't cross the finish line, business presentations/cost reports/etc be damned.

Anyway, enough bitching, I have to finish my flow calcs for next year's undertray...

[mdavis]

Originally posted by BluSTi:
Ok, fun times were had, but I have two gripes, well, three.

1. The faster cars in the autocross should run first in the endurance. If they're going to make any attempt to "normalize" scores, then the faster autocross cars should drive on a clean track and the slower cars should get a track that has already been rubbered in. The way it works now, The slower cars are slow, and the faster cars are doubly (no not doubly, but you get my point) faster because there's more rubber on the track.

2. The cost report is a complete sham. This convoluted process of costing is a joke. Aside from flat-out lying on your cost report, the costs involved are absurd. Here's another idea, provide a MSRP for everything. If you don't have the MSRP, say, for a sponsored part, then a copy of whatever value your sponsor is claiming for their tax deduction. This way, the parts and their associated costs are all searchable and verifiable. Additionally, it removes the "sweetheart deals" that some teams are using.

3. Where were the recruiters? Maybe they hung out at UW the whole time, but in Fontana they were aggressive and numerous. This competition isn't about building a race car, and it isn't about a learning process. This competition is really about getting jobs. Specifically, getting jobs in the motorsport industry. I was really disappointed in the lack of recruiters I saw this year.

4. (I lied about there being 3 gripes, sue me.) If we finished 24th in the enduro, and there were 27 teams that finished overall, I feel that we shouldn't have gotten 30th. Yeah, I know why, with points etc, but there are three teams that didn't finish the race that beat us? How does that logic work? There should be either a penalty for not finishing, or a bonus for completion, but the last time I checked, you can't win if you don't cross the finish line, business presentations/cost reports/etc be damned.

Anyway, enough bitching, I have to finish my flow calcs for next year's undertray...

Some of these things are going to sound brutal and cold hearted. No personal offense intended, but you've now seen the level of competition at these events. It's gone up a ton in the 3 years worth of competitions that I've been around.

1. You could call the rubbered in track a perk of doing well in autocross. If you want that advantage, drive faster in that event. But this is a risk/reward type of thing. Weather, a blown engine oiling the track (both examples from MIS), etc. are a really easy way for the top autocross teams to get screwed during endurance.

2. You guys did decent in the actual cost portion. It looks like it was report quality and a penalty that cost you a lot of points in the event. Those are things you control. The event is pretty clearly defined, you choose the level at which you compete.

4. Total points are total points. The way you score those points are again defined in the rules. You choose the level at which you compete, and how you feel about it afterwards. The penalty for not finishing is 0 points, and the reward for finishing is points. It's that simple. The efficiency score can add in a lot of points if you don't finish, which throws a nice wrench into things (we gained 44 points in Michigan without finishing endurance, which we weren't expecting) but it is part of the game we're choosing to play as competitors.

[Z]

Originally posted by slicktop:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Z:
Much as I like the overall concept of Cal-Berkeley's car, there are nevertheless many details that can be improved.

The chassis, for one, is poor. Frankly, it is typical of all the FSAE spaceframes I have seen in that it is far too complicated, has terrible load paths, and consequently has more weight and less stiffness than it could/should have. I figure it has about twice as many tubes as are necessary, and probably three times as many nodes (all of which take time to cut and weld).
I was wondering if you could be a little more specific about what it is that you find to be poor design in Cal-Berkeley's spaceframe (or any other team's chassis for that matter), particularly in regards to the load paths and excess tubes. There's a nice picture of their chassis in the link on page two. </div></BLOCKQUOTE>
Slicktop,

Firstly, my comments about there being "twice/three times" as many tubes/nodes as necessary was a bit of hyperbole. But there is a lot of complication there that is unnecessary, and the load paths are not good. Secondly, this is a very big subject, best explained with lots of pictures (and by your teachers! http://fsae.com/groupee_common/emoticons/icon_smile.gif), but I will try to give what constructive comments/criticism I can here.
~~~o0o~~~

STRUCTURAL REQUIREMENTS OF CAR CHASSIS - In general (and "big picture") terms, the "worst case" loading condition has the car supported on a pair of diagonally opposite wheels, with all the other parts of the car, such as driver, engine, fuel tank, bodywork, and the other two wheels, hanging of the "diagonal bridge" that spans between the two opposite corners. The vertical loads from all these parts includes gravity, aero, and any inertial loads resulting from vertical acceleration (the car may have left the ground over a hump, and now lands heavily on high ground under its diagonally opposite corners). There are also many little details about how to feed loads locally into the chassis, but no space to cover those here.

The above loading condition includes a large "torsional" component about the car centreline. Building a car that is strong enough to survive the above loads also means that it should be stiff enough for easily tuned handling (via LLTD, etc.). FSAE cars are small and light (and slow) enough that they can get away without too much strength or torsional stiffness, but for a given weight more strength and stiffness will never hurt them.

The obvious overall chassis shape to carry the above "major load paths" is an "X" shape in plan-view, with a wheel at each corner of the X. The X's two diagonals are thus two intersecting beams that carry the major loads, and in side-view they should look roughly like "bridges" (ie. roughly like a wide "A", or arch bridge). A typical V-engined Formula car is not far from this shape. It has a strong box-shaped fuel-tank at the centre of the X, the driver sits between the two forward facing arms of the X (which form the cockpit sides), and the two cylinder heads and sump-plate of the stressed engine form the rearward facing arms of the X.

Here is (hopefully) some ascii-art of the Gordon Murray designed McLaren F1 three-seat "supercar" of the 1990s.

.....^front^.....
FL<--d-->FR
..p.X..d..X.p..
...p.X.d.X.p...
...p.XOX.p...
...s.X.e.X.s...
..s.X..e..X.s..
RL<--g-->RR

(With, FL = front-left-wheel, etc., , p = passenger, d = driver, O = fuel tank, s = storage space, e = engine, g = gearbox.)

The Xs represent the main arms of the (carbonfibre) chassis, with these "crossing over" around the central, and very strong, fuel tank "O". The two front arms conveniently form deep armrests either side of the driver's bucket seat. This car is an excellent example of packaging a great deal (three people + 6L V-12...) into a very compact overall package. Well worth studying...
~~~o0o~~~

Getting back to FSAE, these cars are obviously even smaller than the quite compact McLaren F1. Roughly speaking, the engine is where the fuel tank "O" is in the above sketch, and the rear-wheels are either side of this. Building a strong and stiff (ie. fully triangulated) "torque box" around the engine, and using the mandatory side-impact tubes as in the above sketch, is a good way to get high torsional stiffness (look up "encastre" beams vs beams with cross-sections that are free to deform). And a whole lot of other things.....
~~~o0o~~~

Getting back to the Cal-Berkeley chassis (http://fsae.berkeley.edu/index.php/2013/05/26/vroom-vroom/rg6wdtia3rry56qeeil5u1hgfazb7rm-i8icf7n5hji-3/). Some criticisms (IMO)...

1. The loads from the rear-wheels, which should be following paths generally towards the diagonally opposite wheels, instead head almost straight upward to the spring-damper mounted at driver's head height! Then the loads have to come back down to the chassis side rails via the long and narrow triangles either side of the engine. A much more direct route, with the heavy S-D and its rocker mounted much lower, would be better.

2. Still at the rear of car in side-view, either side of the engine are four diagonal tubes. the bottom two form the abovementioned narrow triangle, and the top one is the mandatory main-roll-hoop bracing. Why the second-from-top tube??? I guess it is to strengthen the S-D mount, but it is not really necessary.

3. The side-impact tubes, either side of driver, have a big bend (in plan-view) right in the middle of them! These are under compression or tension, so better if straight. Is this for elbow room? It seems there is some removable bracing from the bend forward to the front-hoop. Is this in case of possible scrutineering issues? Anyway, straight sides to the cockpit, or better bracing would be better. I reckon the various templates (plus maybe an inch or so) guarantee enough elbow room, foot room, etc.

4. The upper-wishbone-front-arms feed their loads into tubes that essentially put them in bending (ie. sideways). Not really too big a problem given the low loads in FSAE. But these loads then go forward to the front-bulkhead before heading back to the rest of the car. A more direct path would be better. Ie., continue the upper side-impact tube all the way to the front-bulkhead (which is also better for crash strength).

5. There is a lot of diagonal bracing of the floor under the driver's feet, but then there are large sections of the the floor left unbraced (ie. under driver's seat, although it looks like there is some sort of bolt-on seat bracketry++?). Given the floor needs some sort of panelling anyway, it is probably easiest to simply skin the whole floor with a sheet of steel, spot-welded to the lowest chassis rails. 1 mm thick would be truck-tough and weigh a total of ~4 kg. Production car bodies are closer to ~0.5 mm (~0.020") thick, more than strong enough, and would weigh ~2 kg (then subtract any CF/ally panels, bracing tubes, etc...). This steel floor forms the lower tension member of the diagonal bridge you have to build, and greatly increase strength, stiffness, safety, etc.

Bottom line is that I reckon the mandatory tubing required by the rules is almost enough for the whole chassis. So, front-bulkead for IA, front-roll-hoop, main-roll-hoop, various tubes required to connect these three bulkheads in side-view, the triangulated bracing required aft of the main-roll-hoop, and then a sheet steel floor. A removable engine-differential "bracket" (= "partially stressed drivetrain") triangulates the engine bay, and torsionally stiffens everything up.

Finally, and importantly, take the suspension mounting points to where they suit the chassis (ie. to the nodes of above tubework), not the other way around. Remember, it is the whole package that has to work well, and "suspension kinematics" is a relatively small concern.

Z

(PS. I like Cincinnati's spring-damper actuation! Could you please post some pics, Mdavis? http://fsae.com/groupee_common/emoticons/icon_smile.gif (I tried, but it all got too hard...))

[Mbirt]

Originally posted by BluSTi:
Ok, fun times were had, but I have two gripes, well, three.

1. The faster cars in the autocross should run first in the endurance. If they're going to make any attempt to "normalize" scores, then the faster autocross cars should drive on a clean track and the slower cars should get a track that has already been rubbered in. The way it works now, The slower cars are slow, and the faster cars are doubly (no not doubly, but you get my point) faster because there's more rubber on the track.

2. The cost report is a complete sham. This convoluted process of costing is a joke. Aside from flat-out lying on your cost report, the costs involved are absurd. Here's another idea, provide a MSRP for everything. If you don't have the MSRP, say, for a sponsored part, then a copy of whatever value your sponsor is claiming for their tax deduction. This way, the parts and their associated costs are all searchable and verifiable. Additionally, it removes the "sweetheart deals" that some teams are using.

3. Where were the recruiters? Maybe they hung out at UW the whole time, but in Fontana they were aggressive and numerous. This competition isn't about building a race car, and it isn't about a learning process. This competition is really about getting jobs. Specifically, getting jobs in the motorsport industry. I was really disappointed in the lack of recruiters I saw this year.

4. (I lied about there being 3 gripes, sue me.) If we finished 24th in the enduro, and there were 27 teams that finished overall, I feel that we shouldn't have gotten 30th. Yeah, I know why, with points etc, but there are three teams that didn't finish the race that beat us? How does that logic work? There should be either a penalty for not finishing, or a bonus for completion, but the last time I checked, you can't win if you don't cross the finish line, business presentations/cost reports/etc be damned.

Anyway, enough bitching, I have to finish my flow calcs for next year's undertray... 1. The slow cars aren't slow due to the amount of OPR on track.

2. Statics are your friends. You don't need rare driver talent, a big budget, and lots of manpower to be a top contender in them. Learn the game, play along, and profit. My team has had its best season ever capped by a seventh place finish at Lincoln with a strong focus on performance in static events.

3. While it's true that I didn't get to talk to the ladies of Space-X and Raj Nair at Lincoln like I did at MIS, it's not fair to say that there weren't networking opportunities to be snagged.

4. I'm with mdavis. The current endurance scoring does a great job rewarding a finish and penalizing a DNF.

[mdavis]

Originally posted by Z:


2. Still at the rear of car in side-view, either side of the engine are four diagonal tubes. the bottom two form the abovementioned narrow triangle, and the top one is the mandatory main-roll-hoop bracing. Why the second-from-top tube??? I guess it is to strengthen the S-D mount, but it is not really necessary.

Z

(PS. I like Cincinnati's spring-damper actuation! Could you please post some pics, Mdavis? http://fsae.com/groupee_common/emoticons/icon_smile.gif (I tried, but it all got too hard...))

Z,

I would imagine that the 2nd from top tube is to help support the shoulder harness bar, since it is mounted quite close to the main hoop (rules require that the bar must be kept from rotating or something like that, we've never run a harness bar that way, so I don't know the exact wording).

As for our spring/damper actuation, I'm also a big fan of it. It reduced frame build time pretty significantly by reducing the number of frame jig points by 4 and removing a couple of pain in the a$$ tubes to cut/fishmouth (the ones between bellcranks on our previous pullrod setups).

Here are some links to pictures:
front:
https://fbcdn-sphotos-a-a.akam...661_1928147013_n.jpg (https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash4/405882_545768172140661_1928147013_n.jpg)
https://fbcdn-sphotos-c-a.akam...087_1969609803_n.jpg (https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn1/1010264_564967243554087_1969609803_n.jpg)
me in tilt, also front damper:
https://fbcdn-sphotos-g-a.akam...2550_704556415_n.jpg (https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash4/1000413_564015946982550_704556415_n.jpg)

rear:
https://fbcdn-sphotos-e-a.akam...171_1819233678_n.jpg (https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-frc1/400723_544556405595171_1819233678_n.jpg)
https://sphotos-a.xx.fbcdn.net...126_1851982330_n.jpg (https://sphotos-a.xx.fbcdn.net/hphotos-ash3/625662_533456856705126_1851982330_n.jpg)

If you guys want to see more pictures, there are a bunch of them on our facebook page at: https://www.facebook.com/bearcatmotorsports

We know our frame has a ton of extra structure in it, especially in the front end. That was our fault for submitting the impact attenuator report before finalizing our suspension and frame design. There's probably 5lbs that can come out of the nose of the car, let alone all the extra stuff elsewhere.

-Matt

[js10coastr]

Originally posted by BluSTi:


3. Where were the recruiters? Maybe they hung out at UW the whole time, but in Fontana they were aggressive and numerous. This competition isn't about building a race car, and it isn't about a learning process. This competition is really about getting jobs. Specifically, getting jobs in the motorsport industry. I was really disappointed in the lack of recruiters I saw this year.



I can't say for sure since I wasn't there... but nope sorry, it's about the learning process. Besides, that's actually more fun than working in the motorsports industry.

[Z]

Originally posted by mdavis:
As for our spring/damper actuation, I'm also a big fan of it. It reduced frame build time pretty significantly by reducing the number of frame jig points by 4 and removing a couple of pain in the a$$ tubes to cut/fishmouth (the ones between bellcranks on our previous pullrod setups).

Here are some links to pictures:
front:
https://fbcdn-sphotos-a-a.akam...661_1928147013_n.jpg (https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash4/405882_545768172140661_1928147013_n.jpg)
https://fbcdn-sphotos-c-a.akam...087_1969609803_n.jpg (https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn1/1010264_564967243554087_1969609803_n.jpg)
me in tilt, also front damper:
https://fbcdn-sphotos-g-a.akam...2550_704556415_n.jpg (https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash4/1000413_564015946982550_704556415_n.jpg)

rear:
https://fbcdn-sphotos-e-a.akam...171_1819233678_n.jpg (https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-frc1/400723_544556405595171_1819233678_n.jpg)
https://sphotos-a.xx.fbcdn.net...126_1851982330_n.jpg (https://sphotos-a.xx.fbcdn.net/hphotos-ash3/625662_533456856705126_1851982330_n.jpg)

If you guys want to see more pictures, there are a bunch of them on our facebook page at: https://www.facebook.com/bearcatmotorsports
...
-Matt
Matt, Thanks for pictures! http://fsae.com/groupee_common/emoticons/icon_smile.gif
~~~o0o~~~

To the True-Believers of Rockers-and-Push/Pull-Rods,

Did thunderbolts rain down upon Cincinnati because of their heathenism?

Would they have gone faster if they were more righteous??

Is 9th place overall so bad???

(Have I drunk too much coffee today????? Err, that last one is a "Yes"! http://fsae.com/groupee_common/emoticons/icon_smile.gif )

Z

[mdavis]

Originally posted by Z:

Matt, Thanks for pictures! http://fsae.com/groupee_common/emoticons/icon_smile.gif
~~~o0o~~~

To the True-Believers of Rockers-and-Push/Pull-Rods,

Did thunderbolts rain down upon Cincinnati because of their heathenism?

Would they have gone faster if they were more righteous??

Is 9th place overall so bad???

(Have I drunk too much coffee today????? Err, that last one is a "Yes"! http://fsae.com/groupee_common/emoticons/icon_smile.gif )

Z

Z,

There's still a lot more pace in the car, even without aero. More efficiency too, as we found out in Lincoln. And there's plenty of extra weight in the car that can be removed next year (hopefully). From my talks with the guys that will be continuing on the team for the next couple of years, they plan to continue the direct acting setup for a couple of years, so it will be interesting to see how the concept progresses, especially with less weight.

I even included a picture of our ultra-not secret balance tuning devices (aka spring rubbers) for you, Z. I figured you'd like that, with your talk of elastomeric springs/dampers F500 style.

-Matt

[Z]

Originally posted by mdavis:
I even included a picture of our ultra-not secret balance tuning devices (aka spring rubbers) ...
Matt,

It didn't click at first. I thought "Huh...? Why are they putting their bump rubbers on the OUTSIDE of the springs?"

But it makes a lot of sense now. Quickly inserted spacers take half-a-coil or more out of action, and stiffen the spring-rate up (who needs ARBs!). Plus they act as quickly adjustable bump rubbers for shorter overall travel with smoothly rising rate... I like them! http://fsae.com/groupee_common/emoticons/icon_smile.gif

Also, the way you have kept the dampers (fairly standard FSAE Ohlins style?) in original condition, just with a clamp-on extension, is good. And the spacer adjustment for ride height in that extension also looks sensible... http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

[mdavis]

Originally posted by Z:
Matt,

It didn't click at first. I thought "Huh...? Why are they putting their bump rubbers on the OUTSIDE of the springs?"

But it makes a lot of sense now. Quickly inserted spacers take half-a-coil or more out of action, and stiffen the spring-rate up (who needs ARBs!). Plus they act as quickly adjustable bump rubbers for shorter overall travel with smoothly rising rate... I like them! http://fsae.com/groupee_common/emoticons/icon_smile.gif

Also, the way you have kept the dampers (fairly standard FSAE Ohlins style?) in original condition, just with a clamp-on extension, is good. And the spacer adjustment for ride height in that extension also looks sensible... http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

Z,

They worked quite well. There weren't any spring rubbers for small FSAE springs, but full size rubbers cut in half, then massaged to fit the different coil spacings work quite well. 3 available durometers also provide plenty of options. Design judges didn't seem to like the no arbs setup (especially since we had one in our design report) but I think I did a decent job explaining it at competition. I guess the rest of the guys did enough to help carry us to our Design finishes, even if I was getting grilled, lol.

As for the dampers, they're completely stock Ohlins. The damper cap (aluminum piece that bolts on the top of it) is similar to something we used on our 2009 car (it had a mechanically decoupled suspension that you would really like) just modified to include the ride height adjustment (spacers are nice and repeatable).

-Matt