Lightest steel frame car? Lightest car on 13s? [Archive]

bob.paasch

07-20-2010, 11:52 AM

Originally posted by FS Alum:
With cars that light, why still on 13s? Clearly you guys are talented enough designers to get a steel car that light so packaging the suspension shouldn't be over your heads. 10s would seem more in line with you're car's design philosophy and you would benefit from an increased sprung/unsprung mass ratio...the importance of which I believe is underestimated in this competition.

Not to mention the potential difficulty in getting 13s up to operating temperature with a car under 180kg.

Adambomb

07-20-2010, 01:56 PM

Originally posted by AwesomeAlvin:
Single Cylinder or 4 Cylinder?
Wings or No Wings?

Adding those specs would make this thread ALOT more meaningful.

Cheers!
AA

In our case single, no wings, so basically the lightest of the light in those aspects (which is why they weren't mentioned).

Personally never gave much thought to the importance of sprung/unsprung mass ratio...may have to think about that some more. Although with some appropriately sized CFRP rims the difference in unsprung mass could be relatively small I imagine. With 3-piece Mg center Keizers (13x6 front, 13x8 rear) we're currently at about 21-22 lbs unsprung mass all around. I suppose we could probably lose 3 lbs a corner or so with some good CFRP rims, maybe 4 or more with centerlocks.

Beyond that we've honestly never really thought too hard about 10s. Don't have a ton of data, nor is the data we do have very pretty, but what we've got suggests the 13s have no problem getting up to temp (main reason we haven't looked at 10s much). The overall footprint wouldn't appear to be drastically different what with having roughly the same ballpark height and width, so from a [half-blind] guess it would appear you're more or less trading rim diameter for sidewall height, which also brings a drop in cornering stiffness. Although there is the option of the LC0 compound with the 10s, which frankly I know very little about, and would like to look at. As for packaging, surely we could, just not sure if we'd prefer to.

I haven't seen Penn State's 2010 car, although I remember their 289 lb single car from 2009. I'm guessing the jump from 289 to 370 came a good chunk from the engine and a bit from not being able to use Ti for the chassis anymore. That's still pretty damned impressive for a spaceframe with a four.

OK, so Penn State and TU Delft have taken the podium for space frame cars. So that leaves:

A. 13" cars under 373 lbs?
B. Are 13s on a sub 400 lb car even a good idea?

And......GO!

P.S. I would love to just wave around some fantastic competition results, but unfortunately we STILL had teething issues with the single that left us high and dry at competition (for the second year in a row), so unfortunately we really don't have any sort of benchmark for it or anything. Would have actually been nice if we would have finished endurance (or autocross) so we could have contributed to the Optimum G tire temp testing. Although, when it works, it sure does FEEL FAST! http://fsae.com/groupee_common/emoticons/icon_wink.gif

Yellow Ranger

07-20-2010, 08:02 PM

I know OUs 09 car was 396 with a twin (the ape is pretty light) and wings. We ran 20.5x7 hoosiers and really didn't have any problems getting them up to temperatures. Didn't do any testing with the 20.5x6 although, I think if we have hotter than hell temperatures at FSAE West again (a la 06/07) it might cook them pretty quick...

Zac

07-20-2010, 08:22 PM

I haven't seen Penn State's 2010 car, although I remember their 289 lb single car from 2009. I'm guessing the jump from 289 to 370 came a good chunk from the engine and a bit from not being able to use Ti for the chassis anymore. That's still pretty damned impressive for a spaceframe with a four.

The jump was the other way, they were running at 370-ish for a couple years in a row, when they were running the 4-cylinder and 13" Avons. In 09 they dropped about a hundred pounds just from the engine and wheel package change. From what I remember the 08 and 09 cars looked pretty similar to each other.

but I don't think they ever ran a full titanium frame. they used to hava ti rear subframe but that obviously got dropped because of rule changes.

but I honestly haven't seen anyone struggling to get some heat into their tires because they have a light car. I think usually it has more to do with the aggressiveness of the driver and the suspension setup than anything.

AxelRipper

07-20-2010, 08:29 PM

penn state at MIS this year was 293 IIRC.

Kirk Feldkamp

07-20-2010, 08:40 PM

I remember talking to a team a few years back that had done both. Just on wheel and tire alone, there wasn't *much* of a weight difference. Like Adambomb said, there's not much of a difference in tire height or width either. Talking to the guys that have dug through all of the FSAE tire data, there didn't seem to be very many superb options for 10" tires. With the recent development efforts the tire companies have been making with the 13's, I would think there would be a "better" tire in that bunch anyhow. I know in most areas, the 10's are fairly hard to come by these days too. I can think of a handful of race classes that use these 13" slicks, but only one that uses the 10's. I know teams that have really worked through the trade studies on their entire vehicles (Global Formula Racing, RMIT, I'm looking at you guys) have decided to go with 10's, so there must be *some* compelling evidence to go that route! I don't know their full rationale necessarily, but my guess is that when you get right down to it, there's probably not a HUGE difference one way or the other. Empirically, there sure isn't a major difference at comps around the world year after year. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Another thing worth pointing out at this point in the discussion is the concept of a survivor bias. It's the age old case of "F1 does it, so I should do it too." The reality is there are solid teams that have and will continue to win using either design philosophy. The ones that have risen to the top (the ones we're talking about) have a whole lot more going for them than a single component choice. More to the point, think of all the unrelated failures teams have had running either tire. Why aren't we talking about how the majority of the teams running X size tire have failed instead? It would seem to be a much larger sample size than the standout teams at the top. In the end, I believe it's more important to be able to justify and quantify your goals, and have enough time to test and validate your assertions. Basing your thinking around "University So And So did it" is a great way to run yourself in circles.

-Kirk

thewoundedsoldier

07-20-2010, 11:23 PM

I'm designing a car this year that can accept both 10" and 13" wheels. Everything from the tire to the a-arms is different from package to package, and it looks like the weight savings will be 8-12 lbs. per corner. The kinematics on this are NOT easy.

You don't need to give up cornering stiffness to run 10s either.

Another point of distinction could be differential running teams vs. locked rear teams. The differential seems to be something that adds appreciable performance, but at the cost of significant weight. I still keep a picture of RIT's diff housing from '09 under my pillow at night.

flavorPacket

07-20-2010, 11:26 PM

Originally posted by Kirk Feldkamp:
I remember talking to a team a few years back that had done both. Just on wheel and tire alone, there wasn't *much* of a weight difference.

13" wheel: 6 lb
13" tire: 11 lb

10" wheel: 4 lb
10" tire: 7 lb

Your information seems out of date, Kirk.

For what it's worth, Michigan's 08 car on 10s weighed in at 397 with a turbo f4i and a dry sump.

Zac

07-21-2010, 05:44 AM

13" tire: 11 lb

Your information seems out of date.

Demon Of Speed

07-21-2010, 06:42 AM

Side notes:

Singles weigh around 80 lb and 4's weight around 140 lb. So just a switch in what engine is 60lb difference.

Using 13in rimes gives around 100lb of unsprung mass. If the car weighs 400lb total, 1/4 of the weight is unsprung which is far from idea. Most production cars are in the range on 10-20%.

flavorPacket

07-21-2010, 08:48 AM

Originally posted by Zac:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">13" tire: 11 lb

Your information seems out of date. </div></BLOCKQUOTE>

Feel free to correct me, Zac. I haven't weighed a 13" tire since 2007.

EDIT: I called my friend who put a 2696 on a scale and got 10.82 lb. Looks like you're wrong too, Zac.

bob.paasch

07-21-2010, 09:04 AM

Originally posted by Kirk Feldkamp:
I remember talking to a team a few years back that had done both. Just on wheel and tire alone, there wasn't *much* of a weight difference. Like Adambomb said, there's not much of a difference in tire height or width either.

Okay, I just went down to the shop and weighed some tire/rim/center combos. The 13" were 15 pounds, the 10" were 11 pounds. That's about 30%. The 10" tires are 18" OD, 10% less than the 20" OD that most 13" teams run. (Professor mode on) think about rotational inertia...

Talking to the guys that have dug through all of the FSAE tire data, there didn't seem to be very many superb options for 10" tires. With the recent development efforts the tire companies have been making with the 13's, I would think there would be a "better" tire in that bunch anyhow. I know in most areas, the 10's are fairly hard to come by these days too.

If you're going to run 10s, you'll be running Hoosiers. We'd love for Goodyear or Avon to introduce a 10" FSAE tire, but it's not happening any time soon.

There is, however, a superb option in 10s. Bear with my logic. Many of the top 13" teams run the R25B compound Hoosier. The fastest car at Michigan, Stuttgart, was running 13" Hoosier R25B. The same R25B compound is available for the 10"tire as well, yet all the top 10" teams run the LC0 compound Hoosiers. We've tested them back to back, and our drivers prefer the LC0.

I can think of a handful of race classes that use these 13" slicks, but only one that uses the 10's. I know teams that have really worked through the trade studies on their entire vehicles (Global Formula Racing, RMIT, I'm looking at you guys) have decided to go with 10's, so there must be *some* compelling evidence to go that route! I don't know their full rationale necessarily, but my guess is that when you get right down to it, there's probably not a HUGE difference one way or the other. Empirically, there sure isn't a major difference at comps around the world year after year. http://fsae.com/groupee_common/emoticons/icon_wink.gif

We took a lot of tire temperature data last year. If you're going the light (325 lb) single route (ETS, Delft, RMIT, GFR), 10s are the only way to go. More interesting would be Michigan's rationale for using 10s on a 400 lb 600 cc 4 cylinder car. They're bloody fast.

Adambomb, my apologies, but I hardly see the point of "lightest 13" car." We could put 13s on our '10 car and still be under 330 lbs, but it would make us less competitive. At 373 lbs, the ISU car would probably be faster on 10s.

AdamL

07-21-2010, 09:15 AM

Originally posted by FS Alum:
Brookes isn't far behind...379 lbs I think (someone correct me if I'm wrong) with a steel spaceframe on 13s.

With cars that light, why still on 13s? Clearly you guys are talented enough designers to get a steel car that light so packaging the suspension shouldn't be over your heads. 10s would seem more in line with you're car's design philosophy and you would benefit from an increased sprung/unsprung mass ratio...the importance of which I believe is underestimated in this competition.

Yup, spot on. We were at 172kg - 379 lbs at FSAE.

I agree with some of the points made in here and i think alot of people will be surprised with what this university rolls out with next year.

When we're at this weight, running a single, we've gotta go for 10's.

flavorPacket

07-21-2010, 09:28 AM

Originally posted by rp:

More interesting would be Michigan's rationale for using 10s on a 400 lb 600 cc 4 cylinder car.

You answered your question already, rp:

Originally posted by rp:

Not to mention the potential difficulty in getting 13s up to operating temperature with a car under 180kg.

400 lb = 181 kg

Originally posted by rp:
think about rotational inertia...

Not to mention that an LC0 costs $100 and a Goodyear costs nearly double that.

FS Alum

07-21-2010, 10:42 AM

Originally posted by rp:

Not to mention the potential difficulty in getting 13s up to operating temperature with a car under 180kg.

Completely agree, Bob. Further to that, you only need to look at every teams' post-endurance tyres to see that very few are wearing/using them to their potential. I'm of the opinion that every FS car should be on 10s though...the old saying of the perfect racecar being one that crosses the line and then falls to bits comes to mind...that doesn't work so well for teams that do multiple comps though.

Thomas MuWe

07-21-2010, 11:12 AM

As one of the "chosen" one that ran a car with 181 kg (FS UK 2008) on 13" wheels with steel space frame I have to add some thoughts:
We never (in words never http://fsae.com/groupee_common/emoticons/icon_biggrin.gif ) had problems with tire temperature unless the outside temperature was under 15° C. So I can't agree with Bob and FS Alum.
It is not all about being light, it is about getting the power down properly - via a steel spaceframe or a moncoque. In our case we had 84 hp and 80 Nm of torque. So this is a lot and the problem is that you can spin the tyres nearly all the time. During the first phase of acceleration we had nearly 100 percent slip.
As a result, it is not about a lightweight car, it is about a complete concept. The power to weight ratio of a 13" 180 kg car with 70 kg driver seated is about 3 kg/hp. For a 10" 140 kg and 70 kg driver is about 3.5 kg/hp. And the last few years this is probably the way to go and win?!
However we go in the list with a 400 lb 13" car. During the year 2008 we never saw a lighter 13" wheel car in Europe. In Michigan I had no time to go through the pits check the cars out.

@Bob:
It about a good combination of fast cars with fast drivers - it is not only about the car(s). You made a good call with GFR bringing together some of the best drivers in the FSAE world from different universities in one car.

Thomas Müller-Werth
suspension jr08 / jr08evo
joanneum racing graz

Adambomb

07-21-2010, 01:10 PM

Bob-no offense taken. Admittedly there hasn't been much thought to whether the 13s were still "ideal;" to a large extent they were a carry-over from our four cyl. years, and deemed adequate based on our testing. Also kudos on GFR, I remember hearing about the challenges involved in a previous thread, and looking at competition results it sure looks like it paid off! I don't remember the last time a car got a top 10 overall finish without finishing endurance, that really says something about the overall points strategy.

Beyond that, it appears that the 10 vs 13 debate has come out again, and in many ways it sounds a lot like the four vs single/twin debate. I would also agree that likewise, in FSAE at least, what size of tires you're running is still relatively much less important than having a reliable, well sorted out car, having fast drivers, etc. etc. Good "bench racing" though, I do like hearing everyone else's opinions and experience.

Wounded soldier: Sounds like a lot of us would be interested in hearing how your direct 10 vs 13 comparison goes, if you're up for sharing. http://fsae.com/groupee_common/emoticons/icon_wink.gif

It does sound like there are generally little to no problems getting 13s up to temp, empirically speaking at least (would be really nice to get actual dynamic tire temp data from endurance...something we've never had yet). Although from the testing we've done ultimate tire temp under endurance conditions was very strongly dependent on driver. I imagine aero would also favor 13s.

Thomas-I'll agree on the weight vs. traction stance. Very much a trade-off. Whether the 13s actually make more grip under our conditions I can't comment on directly not having any direct experience with 10s, although it would appear so looking at TTC data. From there (and much like the four vs. single/twin debate), the trade-off does look like performance vs. weight (and inertia). Again, still doesn't appear to be a very clear overall advantage either way. Naturally weight is important, but I still can't help but think about the fact that our fastest driver is 60 lbs heavier than our lightest driver, and our second fastest driver is 135 lbs heavier than our lightest driver!

thewoundedsoldier

07-21-2010, 03:10 PM

I read on Delft's website that they built their car on 10s but that the design accepts 13s. I don't know if anything in the suspension or wheel package changes or if they just throw a 13 on without changing anything. The hard part is keeping ride height the same from tire to tire (the reason I am designing entirely different packages).

The point about driver weight is comical. It sucks that you can spend days optimizing ounces out of an upright and then the night before endurance your driver decides to eat a twinkie and gives it all back.

I am 6'3" and 210 lbs. It sucks to be me.

Adambomb

07-21-2010, 04:25 PM

Originally posted by thewoundedsoldier:
I am 6'3" and 210 lbs. It sucks to be me.

Come to Iowa, you'll fit right in! Our fastest driver this year was 6'0" and 200 lbs. One of our competition autocross drivers was 6'5" or so, and had to order his own special fire suit and size 17 driving shoes. Needless to say we've never had problems with the Percy templates. http://fsae.com/groupee_common/emoticons/icon_wink.gif

JasperC

07-21-2010, 04:39 PM

as far as lightest car on spaceframe, I do believe both Penn state and TU delft have broken the 300 lb mark with a spaceframe.
We've never built a car with a full spaceframe, but our 2003 car weighed 135kg with a monocoque at the front and spaceframe at the rear and 13 inch wheels. Supercharged single cylinder engine (KTM 550cc I believe).

You guys can do the conversion to pounds yourselves if you need. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Tom W

07-21-2010, 11:39 PM

Originally posted by Thomas Müller-Werth:
As one of the "chosen" one that ran a car with 181 kg (FS UK 2008) on 13" wheels with steel space frame I have to add some thoughts:
We never (in words never http://fsae.com/groupee_common/emoticons/icon_biggrin.gif ) had problems with tire temperature unless the outside temperature was under 15° C...

Thomas Müller-Werth
suspension jr08 / jr08evo
joanneum racing graz

I don't suppose anybody would like to speculate on what they consider a reasonable tyre temperature?

At the Claude conference that I went to some years ago I believe he stated that in his opinion no FSAE team was operating their tyres at a high enough temperature...

Hector

07-22-2010, 12:52 AM

As a team that has seen tyre temps of 115 C (240 F) I respectfully disagree....

At that point you can smear the rubber off with your hand, except it gets burned in the process.

Thomas MuWe

07-22-2010, 01:07 AM

@Tom:

That is Claude's opignon. I respect that. IMO the "best" tyre temperature was that temperature when we were fast and the drivers were satisfied with the handling and the car was not sliding. And at some stages the tyres were too hot and the car went crazy. Last year - after Detroit we drove at 40° C outside temperature - something about 100° F and after 2 laps Endurance the car was just sliding because the tyres were far too hot. So I think I can pretty much talk about, what the right operating temperature of the AVON or Goodyear tyres are / were for us. And at the end the tyres have to last 22km of Endurance and at 90°C out of my experience that does not work out.

But back to the topic:
All in all it does not matter if you have a lightweight car or if you use a single or 4-cylinder or if you have a spaceframe or monocoque. It is about having the right people in the team which understand what to do with the concept of your car.
In my opignon the best 13" car which was lightweight and powerful was the TANKIA 2008. :-) Awesome machine. But it had a monocoque.
So long....

Tom W

07-22-2010, 04:16 AM

Thanks guys, interesting responses. I know in our car the tyres wear at visibly different rates with drivers of different weights. I do wish we had some IR sensors to actually measure the tyre temps dynamically and get some real numbers behind it all.

Adambomb

07-22-2010, 08:07 AM

+1 on tire temps, I was at that Optimum G seminar in '07 where he said that. And I will even agree that it doesn't seem right that a 400 lb car could get a set of 20.5x7 R13 tires up to temp, but I have also seen dynamic data from IR sensors that say that we have both met and exceeded the target temp for those tires. Would rather not get into the "hows" of what our target temp was, but I would consider it a more or less standard practice, and our result did correspond well with what others have claimed to be a good temp for those tires. I have also backed this testing up with verifying how quickly the tires can be turned into smoke as well. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

chucked

07-22-2010, 09:28 AM

The University of Western Ontario 2010 car had a spaceframe and 13" keizer mags with hoosiers R25B, and a honda F4i. no aero at all. (edit: 7" wide tires all around)

we weighed in at 444lbs at california, with some fuel

our tire temps after autocross and endurance can be seen at optimum G (car #75), we were one of the cars with above average temps, and we were running in the mid 50s C. which i beleive is a little too low, these temps were core temps and taken about 1 min after finishing.

we finished 7th in endurance, 8th in skidpad, and 5th overall!

we are working on CF rims, and getting a 600RR motor, the motor is 7lbs lighter than our F4i and the rims could lose us 4lbs per corner. so hopefully we will weigh in under 420lbs next year.

Mike Macie

07-22-2010, 09:48 AM

Lehigh had a neat solid axle concept in 04 that was 301 lbs.

Mike Cook

07-22-2010, 09:59 AM

In my experience, with a new hoosier, you need to be at least 115 to 120 to start to get it working. At our last autox we were getting to be around 175 which was too hot and we were actually cooling the tires with water.

Mike

murpia

07-22-2010, 10:29 AM

If we're going to start quoting temperatures, please have the courtesy to append a C or F to your numbers http://fsae.com/groupee_common/emoticons/icon_smile.gif

Regards, Ian

RANeff

07-22-2010, 10:38 AM

Ian, I am going to guess Mike means "F" http://fsae.com/groupee_common/emoticons/icon_wink.gif

We have a regional divisional auto-x this weekend and will be trying to control tyre temps between drivers. It seemed that in CA, over-driving the car in endurance really got the tires hot and greasy. Possible side-effect of the new GoodYears coming up to temp quicker?

Big Bird

07-28-2010, 03:02 AM

Some quick responses to a few points above:

Tyre temperature - we went away from the R25 10" tyres in around 2004, because we couldn't get any heat into them. From memory we were around 50-60 degrees C at best. That was with a 175kg car, 80kg driver, around 45kW. Went to LC0's to get temperature - soft compound, and conveniently designed with enough sidewall and contact patch flex that at the end of the day you can fold them up and take them home in your back pocket.

10's vs 13's - Rotational inertia. Can't remember exact mass values, but quick workshop test indicated 13's were around 20% heavier but had 50% more rotational inertia than the 10's. That was for aluminium wheels, 3 piece custom thin wall 13's vs garden variety Douglas ATV 10's. (Hands up who has measured their wheel rotational inertia?)

Re: Kirk's post and labouring about what the others are doing - when we went to a 450 single with 10's, there were any number of naysayers wanting to tell us we were mad. Usual argument - "For the last ... years, every winner has had a 600/4 with 13's. Why wouldn't you copy the winners?". Equivalent argument - "For the last ... years, every team that has come last has had a 600/4 with 13's. Why would you copy the losers?". My point - the arguments are pointless. Stop looking for silly correlations, start designing a car.

Re: Original topic - are there points available for having the lightest car? Is this an objective worth worrying about? Anyone willing to share their calcs as to how many points a kilogram is worth? Anyone willing to argue that ongoing pursuit of weight reduction always gives a positive return?

Anyone "optimizing" for energy usage, and not just laptimes? Seems to me most treat the economy event as an after-thought...

Cheers all,

bob.paasch

07-28-2010, 07:14 AM

Originally posted by Big Bird:
Anyone "optimizing" for energy usage, and not just laptimes?

One could make the argument that any team that builds a light weight single is implicitly doing this to some degree, at your Level 2/3.

Down on the component level, our endurance ECU maps are optimized for total endurance points, time plus fuel. As a design judge at FSG08, I can say with certainty that TU Graz does this too, and based on their fuel usage history the last three years it is a near certain bet that Delft and Stuttgart are doing the same.

Seems to me most treat the economy event as an after-thought...

I would agree, it appears for many teams this is a low priority. Those teams are going to have a very hard time winning a competition.

AxelRipper

07-28-2010, 07:28 AM

Originally posted by Big Bird:

Anyone "optimizing" for energy usage, and not just laptimes? Seems to me most treat the economy event as an after-thought...

well we haven't done that intentionally yet, but we have somehow managed to take a carbureted 450 to 3rd place in economy last year in cali, then added a fuel injector after said carburetor for this year at MIS to try to fix our problem of being lean on top end, and still managed to come in 3rd in economy.

as much fuel as we try to run through that thing, it always seems to run on air. keep in mind that we had actually drilled the jets out on the carb to try to get more fuel in.

Demon Of Speed

08-02-2010, 07:26 AM

Originally posted by Big Bird:
Re: Original topic - are there points available for having the lightest car? Is this an objective worth worrying about? Anyone willing to share their calcs as to how many points a kilogram is worth? Anyone willing to argue that ongoing pursuit of weight reduction always gives a positive return?

The low the car weight the less energy it takes to accelerate the car, so this SHOULD improve fuel economy.

Gruntguru

08-03-2010, 03:38 AM

Originally posted by Demon Of Speed:
Using 13in rimes gives around 100lb of unsprung mass. If the car weighs 400lb total, 1/4 of the weight is unsprung which is far from idea. Most production cars are in the range on 10-20%. Don't forget the driver. That 400lb car probably races at 550 or more which brings the unsprung down under 20%.

Big Bird

08-04-2010, 01:51 AM

Bob,
I had no doubt your team had a system level strategy for tackling the whole FSAE problem. It shows in the results, (and congrats on that front). I was trying to be a little provocative with the fuel economy thing, mainly towards those who think of this only as a race.

Demon,
Fully agree with your argument, and in fact we have used this principle ourselves. But this is an easy decision to make, as a positive outcome with one factor (light weight) leads to a positive outcome with the other (economy). What is more interesting though is how we address conflicting objectives. For example, more power tends to lead to greater straight line speed (positive outcome), but greater fuel usage (negative outcome). How many teams are investigating and quantifying this conflict in their design decisions? Opinions?

Cheers,

EHog

08-10-2010, 08:43 PM

South Dakota School of Mines and Technology: 413 lbs, steel space frame, 13" wheels, EPIC aero (~30 static lbs).

thewoundedsoldier

08-10-2010, 08:56 PM

I was VERY impressed with the SDSMT car at FSAE West. Do you know any particular reasons why they did not make design finals?

EHog

08-12-2010, 06:58 AM

thewoundedsoldier:

We (SDSM&T) didn't even make design SEMI finals...

Was our design one of the best there? I believe so. There is something to be said about 2nd place in Auto-x AND Skidpad... Anyway, we as a team decided we just did not communicate effectively with the judges. We did not make it to competition in 2009, and in 2010 we only had about 4 people that had actually been to competition before! Overall, it was a very "new" team and we just didn't know what to tell the judges. That is our opinion anyway!

flavorPacket

08-12-2010, 10:22 AM

The design event is where the car supports the students' knowledge, not the other way around. You could bring in a car designed by McLaren and still get 80 points if you don't know anything about it.

MalcolmG

08-12-2010, 01:58 PM

Anyway, we as a team decided we just did not communicate effectively with the judges.
It's good to see a team realise this rather than simply complaining about fairness of judging etc because they didn't do well in design. Our team was always very slack about preparing for the design event and as a result always had middle of the pack results in design, then in 2008 we decided to be more proactive and did a considerable amount of practice during the year and it made a huge difference (2nd in design in Aus). There's so much you can improve upon your results just by being better at communicating your work and knowledge to the judges, and the best way to achieve this is to practice doing it.

skaether

08-16-2010, 02:01 AM

UAS Amberg-Weiden RS10 (2010): Steel frame, 13in Hoosier, 170.5 kg full wet (FSG / FS-UK: 163.5kg)

jerry_tung

08-31-2010, 11:14 AM

Penn State has the lightest car currently and they are steel chassis with lots of Ti components. I don't know why they are so slow on the track. anyone can explain?

Zac

08-31-2010, 01:49 PM

Originally posted by jerry_tung:
Penn State has the lightest car currently and they are steel chassis with lots of Ti components. I don't know why they are so slow on the track. anyone can explain?

Penn State was pretty quick in 2009 during autocross, but ran into some motor issues that kept them out of endurance.

I think this year they ran into a lot of turnover due to graduation. The car still looked to be well designed and constructed, but it might not have been finished in time to get a lot of testing in, or training time for the drivers.

AxelRipper

07-23-2011, 10:06 AM

Bringing this thread back up. Our 2011 car at Cali weighed in at 363 lbs. Steel frame 450ER on 13s.

Of course, Oklahoma's car was much more impressive out there. 338 (?) lb Ape with active aero.

EHog

07-23-2011, 10:32 AM

SDSM&T hit 370 this year with huge wings, ape, steel frame and 13's. I would guess if we tossed on 10's (not a trivial task), we would be significantly closer to the uber impressive Sooners!

Thrainer

07-24-2011, 02:26 AM

Why are you running 13" wheels if your car is <400 lb? (question to all teams with such a car)

Regards
Thomas

CarterMcStud

07-24-2011, 08:54 AM

We had steel space frame for our 2011 car. We weighed in at 325lbs/147.417 kg. http://fsae.com/groupee_common/emoticons/icon_smile.gif Small tires however.

Bemo

07-24-2011, 09:59 AM

Good point Thomas. I'd also expect, that you might get problems getting your tires on temperature quickly if you have a <400lbs car on 13s.

EHog

07-24-2011, 10:40 AM

Originally posted by Bemo:
Good point Thomas. I'd also expect, that you might get problems getting your tires on temperature quickly if you have a <400lbs car on 13s.

Not really an issue when you have wings... big wings...

Mbirt

07-24-2011, 11:05 AM

Originally posted by Thrainer:
Why are you running 13" wheels if your car is <400 lb? (question to all teams with such a car)

Regards
Thomas
The response I was given was "Find us 12 new wheels, 8 slicks, and 4 wets for the price of 4 new 13" R25B's, and then I'll redesign the suspension." Oh well. I'll just keep tuning that 65 lb thumper to turn those 13" Keisers.

Anyone from Toronto, Brookes, Amberg-Weiden, <STRIKE>SDSM&T</STRIKE>, etc care to share why they're also still on 13's? Holding out for the D2704?

[Edited for mention of big wings.]

Lex

07-28-2011, 08:42 AM

The University of Florida has had a steel space-frame for a while, running BBS 13" wheels and no aero, powered by a mighty CBR600RR.

In 2010 our car weighed in at 406lbs and in 2011 weighed in at 448lbs. We have had no issues heating Goodyear or Hoosier tires (not mention during summer testing in Florida). We have recorded carcass temperatures in excess of 250*F for the old Goodyear D2696 on our 2010 car during spring testing. There didn't seem to be any tire temp issues during auto-x but since I didn't have the pyrometer with me I cannot say for certain. We will be running 13" tires due to capital costs and experience base. I can do more with developing a car around these tires and getting everything out of them than I can switching to a new tire size that I don't know anything about. I think that it probably comes down to that for most people.

I also second the statement about design practice and good communication can make and break a team in design.

Dsenechal

07-28-2011, 02:30 PM

U of Evansville's 2011 car officially weighed 351 lbs... space frame and 13" wheels.

Adambomb

07-28-2011, 02:48 PM

Originally posted by Lex:
In 2010 our car weighed in at 406lbs and in 2011 weighed in at 448lbs. We have had no issues heating Goodyear or Hoosier tires (not mention during summer testing in Florida). We have recorded carcass temperatures in excess of 250*F for the old Goodyear D2696 on our 2010 car during spring testing. There didn't seem to be any tire temp issues during auto-x but since I didn't have the pyrometer with me I cannot say for certain.

For the most part I've seen the same thing...there are people who claim "there is no way to get a decent amount of heat into 13s," and then there are people who have actually done temperature testing. I've still never heard of anyone running 13s who couldn't get them up to temperature.

Although again, that's for steady-state temperature (ie endurance), I haven't seen a comparison on heating rates. For the sake of comparison I will say I've seen 20x7 R 13 Hoosiers heat at about 7 deg C per minute on a 450 lb, 50/50 car with 180 lb driver on a relatively low-speed course in July with a track temp of about 40 C.

My $0.02, from what I've seen of earlier rounds of TTC data, the 13s offer more ultimate grip and cornering stiffness, obviously the 10s are lighter, but between the two (and more importantly looking at competition results) the choice between 10s and 13s won't make or break a team. It appears to be a relatively balanced trade-off.