How much does your car weigh?

[James Waltman]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> vinHonda
How heavy are other teams? I thought our car was pretty light in 02.
<HR></BLOCKQUOTE>

This was taken from the Monocoques vs. Spaceframe thread. I thought it would make a good thread on its own.
Lets hear how much everyone's car weighs.
What material(s) did you use? (steel spaceframe, carbon monocoque, balsa wood, etc....)


James Waltman
waltmaj@cc.wwu.edu
Formula SAE
Vehicle Research Institute at
Western Washington University

[David Money]

Our car weighed in at a portly 645 lbs at competition. It wasn't fat, just big boned... The new car will be about 450....if they ever get it finished...or started for that matter.

[vinHonda]

University of Toronto's 02 car weighed in at 449lbs. wet, no driver. I'm not kidding.

We run a steel spaceframe with carbon fibre panels inserted into the side structure.

Good thread. How about other teams?

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Eddie Martin]

University of Wollongong's 2002 car weighs in at 209kg, which i think is about 460lbs. This is the car that just competed in Australia.

The car that was in US in May, we call the 2001 car, was 220kg or about 485lbs.

Both cars run steel spaceframes with a Honda CBR 600.

University of Wollongong
www.uow.edu.au/eng/racing (http://www.uow.edu.au/eng/racing)

[Cats]

We were at a hefty 507 back in May. The good thing is we were 13 lb lighter than our previous car. The frame is still atleast 20 lbs heavy.

dan

[Michael Jones]

Cornell went on a diet in 2002 to lose some of the 475 lb. 2001 car. Like most diets it was a complete success, and the 2002 car weighed in at 486.

The 2003 car is presently on the Atkins diet and is being fed large quantities of meat proteins and fat while being kept away from filler carbs. We'll see how that works, although we're concerned about the long-term effects of bacon fat congealing in the fuel lines.

[terc04]

University of Missouri - Columbia

2002 competition weight was 436 lb.

2003 entry is much stronger so far, at a cost of 5 lbs to the frame, but our driveline is much lighter. We are adding a few extras that may again put us over 450.

[Dominic Venieri]

Rensselaer

2001 - 481 lbs dry (with wings and undertray)
2002 - 497 lbs fully wet (with suspension mounted wings)

2003 - counting ounces to stay under 500 lbs.

www.formularpi.com (http://www.formularpi.com)

[Richard Lewis]

Our first car (2002) was a beast at 577lbs, wet without driver.

This years car will be under the 500lb mark. Much in the way of weight savings have been seen in the wheel ends(4lbs savings per), rear train (~15lbs savings), engine(~20lbs savings), and periphrial systems(more than 20lbs). Even just a switch in rod ends and bolt size could save over 5lbs...

-------------------------
UVIC Formula SAE Team
http://members.shaw.ca/drax77/UVICFSAEcar.jpg
http://fsae.uvic.ca

[loose_nut]

The topics on this site keep getting better and better.

Our last entry was 512 pounds. This year we're hoping for 475 but I'm guessing we'll be closer to 485.

[Charlie]

Auburn's 2000 car was ~460 I believe. Might be a little off. The 2001 car was 470. The 2002 car was 486, but that is wet, which the other's were not.

This year we are trading a bit of weight by switching to steel rotors and gaining some torsional stiffness. We also bought some slightly heavier wheels because our old wheels were not durable enough. But we are losing weight in many areas. We hope to end up right in the same area, if not a little lighter.

-Charlie Ping
Auburn University FSAE 1999-present

[Dan B]

Cal Poly Pomona was 600# even in 2000.
That was with "really big wings", electric supercharger, and 135A GM alternator.

Obviously we want to make a lighter car for this years event.

[Formulastudent]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Dan B:

Obviously we want to make a lighter car for this years event.<HR></BLOCKQUOTE>

Yeah, all the drivers are doing daily 5K runs.
/infopop/emoticons/icon_biggrin.gif

- Dave

[MikeWaggoner at UW]

our 98' car weighed 440 wet, the V8 weighed 430 wet (w/o a starter), and our current car will probably be around 440-450. The '98 car was just measured (we're continuing the design theme) at 2,300 lbs torsional stiffness, and the new one will probably be stiffer.

Western Washington University FSAE
dot.etec.wwu.edu/fsae

[-Gabriel]

École Polytechnique de Montréal

2000 - 579lbs
2001 - 529lbs (2nd year car...)
2002 - 509lbs
for steel space frame cars with ABS bodyworks, and too much small things that make the difference between a over/under 500lbs car...

2003 - aiming for 475 lbs with 115lbs and less drivers
How: reducing weight in wheels, frame and a little bit in engine (newer,so lighter, than previous cars).

By the way, for those who use bathroom scales for weighting the car (yeah money...), did you notice a difference between your readings and the official one at the competition? We noticed a couple of pounds more at the official weighting, even if the claimed precision is less than that. Maybe a matter of weight distribution on the "cheap" scales...

Gabriel Denoury
Formule SAE Ecole Polytechnique de Montréal

[Nigel Lavers]

Our 2002 car weighed in at a monstrous 580lbs wet. We had a few excessively heavy parts that are being upgraded this year including a new engine (-50lbs), smart chromo frame (-15lbs), lighter wheels (-10lbs), lighter bodywork and seat (-10lbs), and many other small lightenings... (-15lbs)

Overall, for the 2003 FSAE comp we should be at ~480!

[Scott Wordley]

Interesting thread, but consider this angle....

The 2002 Monash Car that recently competed in the Australian competition weighed in at 595 pounds or 270kg. (see the picture in the gallery)

Which is quite ridiculous when you consider that the wings and diffusers including mounts only weighed a total of 30 pounds.

That aside, what is even funnier is that fact that we finished second (to winners Wollongong) in Autocross by only 0.04 of a second. With a car more than 135 pounds heavier. http://fsae.com/groupee_common/emoticons/icon_eek.gif
(The fact that we swam through skidpan and accel and broke in enduro(electrical problem) makes any further comparisons difficult).

Which leads me to ask; why is it that minimising weight seems to be THE major design focus these days? Sadly, it does make it simple for the design judges to eliminate a whole lot of good cars on the basis of a single, dubious metric.

Last I checked F still equals M*A ; and there are many ways to increase A that don't involve reducing M.... but does anyone (including the design judges) care? http://fsae.com/groupee_common/emoticons/icon_confused.gif

Regards,

Scott "Maverick" Wordley &
Roan "Goose" Lyddy-Meaney
MOnash FSAE Wingmen

[vinHonda]

It seems as though you have quite good drivers on the team that know how to drive an aero-ed car (I keep hearing that FSAE-A has a 'faster' circuit...... and then sometimes not).

Perhaps Wollongong didn't have as good drivers??

Yes, it is true that you can increase 'F' rather then decreasing 'm'. But the problem here comes down to fundamental engineering: wouldn't you just rather do both??? Our kind of cars are already restricted....so increasing 'F' has a limiting factor! Once you've maxxed that out, the next logical step would be to minimize 'm'...no? And that is what our thread is all about. It's obvious that if you don't need the weight for stiffness.....forgettaabout it.

Light cars are easier to handle too. Let's not forget that!

Though, congrats on your suppppper close second place run to Wollongong!

cheers!

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Scott & Roan:
The 2002 Monash Car that recently competed in the Australian competition weighed in at 595 pounds

That aside, what is even funnier is that fact that we finished second (to winners Wollongong) in Autocross by only 0.04 of a second. With a car more than 135 pounds heavier. http://fsae.com/groupee_common/emoticons/icon_eek.gif

Which leads me to ask; why is it that minimising weight seems to be THE major design focus these days? <HR></BLOCKQUOTE>

Hmmm. I guess you've proven that if you do everything else well then you can have a fast car, even if it is heavy. Like Cal Poly did in 2000. However, probably the most difficult thing to do in design is reduce weight. It involves a lot of engineering to create a part that does the job and is very light. In my opinion, vehicle performance does not always directly reflect design, rather, it is more of a reflection of refinement and testing.

You know if you put your car on a diet you could have beat Wollengong. And I'm sure that you have a goal to reduce a lot of weight next year, right?

-Charlie Ping
Auburn University FSAE 1999-present
http://www.auburn.edu/~pingiii/2002FSAE/carblank.jpg

[Eddie Martin]

Scott,
Okay so your car is heavier, i'm sure you watched both cars on the track and saw that ours was hoping and skipping all over the place in hairpins and tight corners. (a damper problem). If we had got them right we would have been quicker, but everybody says if they could change component X they would have been quicker, it is what happens on the day that counts.

Back to the design event question.

At the Claude Rouelle / MoTeC seminar held in Melbourne last year Claude said cars in the design finals should not be over 450lbs (204.5kg). We asked him about this and he said, "Do you want me to tell you that 500lbs is acceptable? I 'm here to push you to the top not the bottom."

A 205kg car is a lot harder to design and get reliable than a 250kg - 270kg car.

Regards
Eddie Martin
University of Wollongong
www.uow.edu.au/eng/racing (http://www.uow.edu.au/eng/racing)

[Scott Wordley]

It may be harder to design a 205kg car but does that make it a better solution.

The purpose of the competition is to build a car which performs best in a well defined series of events, not to bulid the lightest car. If it requires extra weight to make the car perform better then how can this be seen as a poor design solution. As long as the performance gain offsets any weight increase then the design is an improvement.

Weight reduction should not be made the primary goal at the expense of innovation.

Regards,

Scott "Maverick" Wordley &
Roan "Goose" Lyddy-Meaney
MOnash FSAE Wingmen

[Charlie]

I cannot understand your point. You know a lighter car is faster, how can you say we shouldn't concentrate on weight? Should we add ballast to our cars uner 500 lbs? How is this extra weight making your car perform better?

I mean, you asked why thye judges looked so favorably on cars that were lighter. It's because it's a more difficult design goal. Now you are saying adding weight will help your performance. That can be true in a couple areas such as adding components like wings. But you yourself said that your wings weren't your main weight adder, so what are you saying exactly? http://fsae.com/groupee_common/emoticons/icon_confused.gif

-Charlie Ping
Auburn University FSAE 1999-present
http://www.auburn.edu/~pingiii/2002FSAE/carblank.jpg

[Fergus Wilson]

The goal is to build a car that not only performs in a variety of events, but is reliable. And i'm sure that almost everyone does a quick power to weight calculation to compare other cars - judges included. As we move closer to the theoretical maximum power using current engine technology, other ways of increasing "A" must be found: reducing weight.

Ask yourself: if you could have a reliable, car similar powered with 20kg (or more) less weight, would you do it? In the end the weight of an object is just a compromise between conflicting parameters.

I agree that arbitrary weight limits should not be used when judging the design event. If you can justify the extra weight, perhaps you should only be penalised on the track.

Fergus Wilson
Project Manager
UOW Racing 2003

fw01@uow.edu.au
www.uow.edu.au/eng/racing/ (http://www.uow.edu.au/eng/racing/)

If you've achieved all your goals, you're not ambitious enough!

[Jeff Curtis]

Even though the design judges make a big deal about it. Weight in these cars is not all that critical to performance. The tires for these cars are designed for a 1000 lbs car. If you look at the lateral force vs. load graphs, you'll see these tires are not that load sensitive in our operating area (25-325 lbs.)

To add to this factor, our competition is usually run in freezing cold temperatures. Added weight and added weight transfer, builds up much needed tire heat. The added tire heat may actually result in more grip than the lost grip due to the small amount of load sensitivity experienced.

You could still state the claim that the car needs to accelerate longitudinally and here reduced weight would be of assistance. This is a valid argument, however, in my opinion due the mostly traction limited nature of our long_acceleration, the gains in long_acc do not offset the gains in lateral accelerating due to higher tire temps.

So to conclude, I not trying to say, a heavy car is good (+550lbs), but I do feel like in colder temperatures a car's overall performance (Auto-X, Endurance, skidpad) is not highly sensitive to weight. However, it does play a role in design judging which is worth 150 points.

Jeff

[This message was edited by Jeff Curtis on January 07, 2003 at 10:02 AM.]

[This message was edited by Jeff Curtis on January 07, 2003 at 10:03 AM.]

[David Money]

Everybody knows that a lighter car will be faster (given the same traction) but what good is an ultralightweight car that breaks. A couple of years ago there was a car that the judges just drooled over because it weighed in at somewhere around 372 lbs (169 kg)!! It was all they were talking about, but when it came to endurance it didn't finish from what I heard. Last time I checked endurance was 400 pts total and design was 150 pts total. Hmmmm....where to concentrate? Not hard to see...endurance would be a pretty safe bet. That is exactly where our team concentrated for 02 and guess who was parked on the grid for endruance in 02 when the rain started? I will say that it is much easier to design a car without striving to make everything ultralightweight. It is a hell of a lot faster too. Our new goal is to get the 03 (which will now probably become 04) car down to 430 lbs wet and the new guys are struggling with it because they have to perform analysis on EVERYTHING to get that out of the car and still have it reliable. It's all a trade off. Would you rather have a lightweight car that gets finished May 10 due to extensive analysis or a porker that gets finished March 10 and you know stands a lesser chance of costing your team 400 pts? Choose your poison!!

[Michael Jones]

quote:
***
It's all a trade off. Would you rather have a lightweight car that gets finished May 10 due to extensive analysis or a porker that gets finished March 10 and you know stands a lesser chance of costing your team 400 pts? Choose your poison!!
***

Well put. Penn State's sub-380 car was a work of art but yes it did break - whether excessive weight reduction was the ultimate cause of this I cannot say for certain (I believe it was a drivetrain failure if I remember right...) It also must have been crazy expensive with all the titanium and carbon involved -- again a tradeoff.

The unwritten 500lb. rule seems right in encouraging that these trade-offs are at least considered in design decisions. It's probably easier to build a 550lb. car and it may be sufficiently quick if it's centered, with a low CG and a light driver. Consider our 480lb. 2001/2002 cars have been driven at competition by a 220lb. driver - gross weight, the same as a 550lb. car driven by a 150lb. driver. The extra 70lb. of human cargo didn't seem to matter much in our case - both our endurance drivers were equally quick, despite a 60-70lb. differential.

I'd hypothesize that both cost and design complexity increases exponentially with weight reduction. A reliable 400lb. car is much harder to build than a 450lb. car than a 450 would be compared to a 500 or a 500 to a 550.

[Eddie Martin]

All teams have the same timeframe to work under to get their cars to the Silverdome in May. A team's organizational structure and management should look after getting the car finished and ready on time. If it is the difference between getting to Pontiac and not, I would definitely bring a heavier car, but this isn't the point.

You can never tell me that a heavier car is faster than a lighter one. The top teams will always have their cars ready well before the competition and have them light and have them reliable and they will go well in design if the car is good and you can answer the questions. Look at Cornell last year it was super fast, lightweight, reliable and it easily won design, so it is possible.

People have also talked about the cold weather in Detroit, well in OZ in 2000 the temperature was 35 C (95 F) and the last two years it has got over 25 C (77F) so these cars do need to run in all temperatures.

The car from Penn State that weighed in at 169kg(372lbs) has been mentioned. Well at the FSAE-A competition in 2002 Tokyo Denki from Japan had a car that weighed 165kg(363lbs). This car will probably get under 160kg (352lbs), they said closer to 150kg (330lbs), before it hits Detroit in May. It had a starter motor problem but other than that it ran reliably for an enduro.

Regards
Eddie Martin
UOW Racing
www.uow.edu.au/eng/racing (http://www.uow.edu.au/eng/racing)

[Scott Wordley]

Charlie, I think you missed the point I was trying to make. Reducing weight is always going to be an important factor when designing these cars and its an area which we know we have to focus on. However I don't think that it should be so highly weighted so highly in the design event. Theres are certain systems (wings, turbochargers, etc) that are necessarily going to add weight to the car, but if done properly the increase in performance will more than offset the weight penalty. I don't want to see teams discouraged from trying out these ideas just because they know they will be penalised for it in the design event.

The Tokyo Denki car which Eddie spoke of was so lightweight mainly due to the fact that they were using a single cylinder engine. They chose to build a super-lightweight car at the cost of overall performance. How can anyone possibly argue that this is a better designed car?

Regards,

Scott "Maverick" Wordley &
Roan "Goose" Lyddy-Meaney
MOnash FSAE Wingmen

[ANDONI]

Hello guys..

Still on strike....F&%$% up. Anyways. Just to share our last year´s weight. LOL. Our 2002 car weighted 743 pounds. What do you think our major concern is this year? Well, obviously our goal is a unde 500 car. With that 50 % more weight than most teams, we still got an acceptable 50th place for our first time on acceleration with 4,691 seconds. Hopefully we will get our 2003 car 33 % down. If this happens, prepare for the acceleration event.... http://fsae.com/groupee_common/emoticons/icon_wink.gif

chao

Andoni Mazeika
2002-2003 Team Leader
Equipo F-SAE USB
www.formulasaeusb.com (http://www.formulasaeusb.com)
Universidad Simon Bolivar
VENEZULA

[Eddie Martin]

I think the Tokyo Denki car is great. To give people not at the competition an idea of the car, they are a first year team and were running a single cylinder engine, i think a 400cc Honda, with a carby and for a restrictor they used a washer, so they were only getting about 40hp. For the US comp in May they will have injection and a proper restrictor so should be able to get 60hp. They also had a problem that there starter motor didn't work so had they had to push start it. There is a photo of the car in the photos section of this site.

I agree, Scott, the car was about a second off everybody else on a 34s lap, but they are a first year team and still had not got everything working perfectly, but for a first year team / car it was very impressive. It would beat most first year cars. After a year of development and tuning and getting their drivers up to speed their next year's car will be very good.
I don't understand how you can favour innovations like wings and turbos, but not another innovation like a dramatically reduced mass (F=m*a), they are all very valid I think. Wings, if not done right just hold more sticker and turbos that are not done right just blow smoke or worse. It is what you make of them that is important. Carroll Smith said it was the first single cylinder done right.

Regards
Eddie Martin
UOW Racing
www.uow.edu.au/eng/racing (http://www.uow.edu.au/eng/racing)

[Scott Wordley]

I was not trying to have a go at the Tokyo Denki car, I think it was a fantastic effort. I was merely trying to point out the fact that weight is only one factor in the equation and I don't see any reason (other than the fact that its a simple way to eliminate a lot of cars) why it should be used as a deciding factor in the design judging.

Perhaps a more relevant measure would be power to weight. If we take the Tokyo Denki car as an example with 160kg (352lb) and 40 hp, this equates to a 320kg (704lb) car with 80 hp. I believe they already have dynos at the US comp so it wouldn't be a difficult thing to implement.

I'm not trying to argue that weight reduction isn't important or that it shouldn't be a primary concern, I just think that there are so many other factors affecting performance that weight is not the most relevant way of distinguishing cars. After all, I thought the idea behind the design event was being able to justify and back up all the decisions you made.

Regards,

Scott "Maverick" Wordley &
Roan "Goose" Lyddy-Meaney
MOnash FSAE Wingmen

[Jeff Curtis]

If a lightweight car is sooo much faster, how come Penn States car, which was 25% lighter than Cornell's car in 2001, ran about the same lap times. Yes, you could claim many reasons, but I am telling you in any other form of racing, a car that is 25 percent lighter is going to be much much faster, even with less power and a more poorly designed suspension, which in this case Penn State had neither. This is because most racing cars are running on tires that get up to or over their normal operating temperature and operate in the ultra load sensitive portion of their tire curves.

I am not saying that a lightweight car isn't good from a design standpoint, but it is not like you are going to see huge gains in lap times. Tire heat is where all of the grip in these tires comes from. Why do you think Cornell's cars (medium weight (500 lbs) narrow track width car) consistently run the some of the fastest times in skip pad and autocross (with somewhat less impressive times in the endurance race). Once you begin to focus you suspension design goals into getting the tires up to as high of a temperature as possible will you see the full gripping potential of these tires. A car weighing less 500 lbs is kind of a magic number because with any more weight you are probably starting to see the more load sensitive portion of your tire curve.

To respond to the temperature at the competition, if you'll notice Cornell had a dominant car in 2001 and 2002 when the temperatures were cold, if it were to be 95 degrees throughout the competition, this would probably not be the case. This is part of the design process; this is something you have to think about when designing your car. Design is all about assumptions, in my opinion based on history it is good to make the assumption it is going to be cold at the competition.

Jeff

[Brent Howard]

I think that car weight has alot to do with team preformance, but I would personally rather build a tank that you know isn't going to fail then to shave every gram off and have probelms with fatigue, shearing, bump loading, etc.... Also, lap times are very much based on driver skill, if you have a car that is 50 lb heavier and has had a month of track time you will be able to beat someone who is just taking the car out for the first time. Weight is an important factor, but not the only one, every part of the car must function well before weight can even be a consideration.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[vinHonda]

Mike from Cornell and I just had a nice chat in our race shop. It's not that hard to build a sub 500lbs car. The point Mike was trying to make eariler about going below 450lbs is VERY difficult. As engineers, we should always just strive to make the cars lighter and stronger. That's the whole point of racing, no? True, Penn's state car was suuuuuuper expensive, and that was their tradeoff.

Mike let me know that Ken from UTA was back in the picture........ I'd say get your drivers up to speed, or look out UTA this year!!! I know I'm mak'n sure we have lots of seat time!

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Bob Wright]

To sumarise Monash's (my) position on the issue:

There are definately bigger increases to be made on the 'Force' than there are on the 'Mass'. Last year we had a simple, low refinement car that had a huge advantage in high speed grip. This year when we show up with a car of similar mass and an all conquering low speed traction solution, you will know what I mean.

ps whats with the skinny tyres everyone? The Australian comp isnt in the arctic circle exactly,

you people are whacked, man

Bob Wright
Monash University
Australia

[David Money]

With regards to tires (or tyres as the rest of the english speaking world has a tendency to spell them). Almost every year it is frickin cold and damp in Detroit. Last year we saw it start to snow twice during the week of the competition. As you know tyre warmers are outlawed. http://fsae.com/groupee_common/emoticons/icon_mad.gif So what to do... well the engineers from Goodyear had a new tire last year that was super sticky that was designed to last only the length of the endurance event. The problem is that you need to heat cycle them in BEFORE you get to Detroit because you can't really do it there. That means you would need 2 sets, one for endurance and one for every other event, and you have to have them with you in Aus to ship to Detroit. One of the things that the Goodyear engineers noted was that you need to go with a narrow tire so that you can get them up to operating temp faster...if that's even possible at the comp. Which by the way...they were saying that they took some tire temps and the only place that the tires were getting hot was in the end of the endurance event. Wonder if it actually snow a couple of inches this year in Detroit at the comp. Maybe then they would see the beauty of a Calif comp... http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Charlie]

Argh!

I think most people in the thread probably agree when it really comes down to it, but everyone is taking words out of context.

When you say a lighter car will be faster, it means an otherwise identical car. Nobody ever said a superlight car that is not well engineering is going to win, so no use saying that if Penn State didn't bet Cornell weight is useless.

Time is another horrible reason to say more weight is better. Yes it takes time to shave weight off the car, and like I said, I think that performance at the competition is likely more related to testing time than design IMO. But you don't need to spend hours on every part of the car to get a sub 500 lb car. Concentrate on unsprung and rotational weight first, it will pay the most dividends. Concentrate on your frame because it is a great place to save a lot of weight with just a few iterations. This will put you under 500 lbs from what I've seen. If you don't have the time, then do less, but still concentrate on weight. Here at Auburn we have run the same upright design (or very close) for the last 4 years. They had a lot of weight to be saved in them, however, the time was more impotrant. This year we are concentrating on the upright redesign and stand to gain a lot. Take the load you can handle, budget your time, but still try to save weight!

Tires are an excellent topic of discussion. I can see how a heavier car could properly utilize the tires we run and pull more lateral gs once the tires are up to temperature. Excellent point. There are other ways to get tires up to tempurature faster other than weight, but I can see that helping teams vs. teams that don't realize they are not heating thier tires.

-Charlie Ping
Auburn University FSAE 1999-present
http://www.auburn.edu/~pingiii/2002FSAE/carblank.jpg

[J-P Granger]

I'm wondering... should we assume that all of the weigths mentionned in this thread use 4 cyl. engines? Every once in a while we see a 1 or 2 cyl. engine. They obviously have less power, but since we're just talking about raw mass, I'm sure those cars beat records on the scales...

For our part at McGill:

2001: 560ish lbs.
2002: 493 lbs.
2003: We'll see!!

With a 97 YZF600...

J-P Granger

[Bob Wright]

here is another problem: the weight of wings and mountings aside, how do you make a car capable of 2.5g cornering and 3g braking as light as a 1.5,1.8g car? And more importantly, how then do the design judges benchmark your structural efficiency and scale your additional weight?

Bob Wright
Monash University
Australia

[Angry Joe]

I think there is a practical minimum weight for the car. Ideally lighter is better, but there comes a point when you sacrifice durability and, in my opinion, corrupt the spirit of the competition. What fun is it to make a featherweight car that will break in half a week after competition?

Our 2001 car weighed 540 lbs. The frame was a little porky but most of the excess weight was in the drivetrain (WAY too beefy) and poorly consrtucted bodywork. We are aiming for our 2003 car to be a bit under 500 lbs. And it will still survive cone hits, which is more than can be said for some cars...

Lehigh Formula SAE

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Grant Mahler]

Almost the new year - anyone going on a diet?

[Dave K]

Holy old post batman...

haha anyway yeah, at comp last year we were 476 wet without driver, and we are makin resolutions to lose about 20 or so. We run a 1020 Steel Spaceframe chassis.

[Grant Mahler]

Yes, but I find it interesting that this thread is 5 years old and looking at corner scales at west last spring suggested the average weight hasn't changed all that much. There are of course exceptions but generally speaking the cars are still ~500lbs w/o driver from what I saw.

I find this interesting because the power limits have grown significantly - anyone and their brother is now making 80+hp NA and loads of torque with turbos.

Even cars running "non-standard" motors still weigh too much in my opinion. Delft and Tokyo Denkei both made solid efforts at low weight cars and they both had to make some interesting design considerations to get there.

I find the discussion of where people save weight to get from 500# to 350# much more interesting than "Help Help we need to know how to design suspension" or "Help we need CAD model of motor we don't have" or "Help we don't know anything...do it all for us...". I like this discussion, and I wanted to see anything had changed.

[John Grego]

In 05 our car was 476 with a 4 cylinder. Last year with the Aprilia we were 398, wet with no driver, in California. Hopefully less than that this year. We still run the chromoly chassis.

Weight savings is one of our major goals for the car this year.

[flavorPacket]

we were 426 without turbo in 06. we were 459 last year with one. this year we're shooting for 420 with one, and I think we'll be pretty close.

[Didier Beaudoin]

Originally posted by John Grego:
In 05 our car was 476 with a 4 cylinder. Last year with the Aprilia we were 398, wet with no driver, in California. Hopefully less than that this year. We still run the chromoly chassis.

Weight savings is one of our major goals for the car this year.

It's funny because our car with the Aprilia engine weighs 398lbs too...

[Cakemaker]

Lightest car in the competition? At least in the 06 year...

www.dutracing.nl (http://www.dutracing.nl)

[t21jj]

Last year we were right at 450 with out driver, this year we are should come in at about 370.

[Steve O]

Last years car is 357# with yamaha yfz 450, chrome-moly space frame. Not sure what we will see this year... should be comparable but with a turbo.

Steve

[Chris Aho]

In the general words of an engineer with great wisdom, "Any idiot can make it heavy and strong, but it takes a true engineer to make it strong enough and light as possible."

[Corey H]

Last year we were 398# before leaving for comp, rolled it out in Michigan and some how it gained 6 pounds, so 404 wet officially, chromoly space frame, GSXR 600, aluminum stress skins, no carbon fibre

[Patrick]

Originally posted by caho:
In the general words of an engineer with great wisdom, "Any idiot can make it heavy and strong, but it takes a true engineer to make it strong enough and light as possible."


I'd like to modify that one...

"...it takes a true engineer to make it strong enough, STIFF ENOUGH, and light as possible."

As Claude Rouelle mentioned during this past OptG seminar, "FSAE students have three problems... transients and compliance." He never did mention the third one...

http://fsae.com/groupee_common/emoticons/icon_smile.gif

-Patrick DeGrosse Jr.
NASA - Jet Propulsion Laboratory

[JR @ CFS]

We were 207kg's before we fitted our body...and 241kg´s after! Go figure! We build aesthetically pleasing cars every year and it is a tradition not to roll out a car that looks the same year after year, so although we are penalised heavily (excuse the pun, I couldn't resist!) because of it, we still stand by our decision!

We are aiming to lose a considerable amount of this before rocking up at FSAE West this year though! Hopefully without compromising on looks!

[Jon Oneill]

For the 2007 FSAE-A event our car weighed 278kg. A bit of a beefcake I must admit.
First year team pretty much. Yamaha r6, mild steel spaceframe and lots fo extras.

Odviously for 2008 were making some serious changes to lower tha figure.


Weight watchers here we come!

[Sathersc]

We hit 582lbs at Formula last year, which we feel is a pretty solid first year weight. This year our frame alone is already 20lbs lighter than last year (while improving ergonomics and rigidity) and we're hoping to come in right around the 500 mark. http://fsae.com/groupee_common/emoticons/icon_cool.gif

[GTRR35]

Our car is really a fat cat.
The car weighed more than 350kg(about 771lbs) in 2007.

So,weight savings is the major goal in 2008

[Pete M]

We were pretty heavy at Aus, 220 kg (485 lbs). We're hoping to get about 10 kg (22 lbs) out before detroit.

[ben]

Originally posted by jonnierice:
We were 207kg's before we fitted our body...and 241kg´s after! Go figure! We build aesthetically pleasing cars every year and it is a tradition not to roll out a car that looks the same year after year, so although we are penalised heavily (excuse the pun, I couldn't resist!) because of it, we still stand by our decision!

We are aiming to lose a considerable amount of this before rocking up at FSAE West this year though! Hopefully without compromising on looks!

I can completely see why you get penalised for having a body that weighs 34Kg that's completely unnecessary.

I can understand a desire to be aesthetically pleasing, but even if you stand by that as a goal I doubt you could convince me that you couldn't have done it for at least half that mass.

Ben

[Steve O]

I agree, try a couple less layers of glass or if you are using something else try switching to a material that weights less! Our body typically weighs no more that 20lbs (9kg)

Steve

[terra_dactile]

A little history of our diet process since i have been a member of the team, we would put a goal every year on the wall for each section of the car notifying each group how much they needed to save, we called it Slim Fast.

2004 FSAE east 495 lbs Yamaha R6, carbon monocoque, 85 Hp
2005 Fstudent 369 lbs Yamaha Wr450f carbon monocoque, 35 HP
2006 FSAE east 377 lbs Yamaha Wr450f carbon monocoque 42 HP
2007 FSAE east 336 lbs Yamaha Wr450f carbon monocoque, 48 HP
2008 & aprox. 320 to 330 lbs yamaha wr450f carbon monocoque, 52 to 55 Hp

Its has been a long road from a 500 lb car in 2004, saving weight while increasing rigidity has been an amazing engineering experience.

Jude Berthault
ETS FSAE 2003 to 2008
Team Leader

[Pete M]

And yet the power to weight ratio of your 04 car was still higher. Have you done any back to back comparisons with that car to see which is faster? Not a fair test i guess, because i imagine you've probably improved other aspects of your car since then. I'm just curious as a member of a team with a 485 lbs car whether sacrificing power to weight for weight actually made the car faster or not.

[Steve O]

Pete, I know we just had a similar discussion but it seems as though you may be brushing on the smaller engine topic again? From my experience I feel that the smaller engine suffers less from that restrictor lag coming out of corners or on initial take off...other than that I can't really compare because the cars have just gotten overall better like you mention. I also like the packaging of the smaller engine. This year it seems like we will be looking at around a 340-360lb space frame wet weight. Unsure of our final hp yet but we had around 60 NA.

Steve

[lporter]

We have a tradition of spray painting the weight of our cars on the shop wall after we get back from competition. Here's a little taste of RPI's history, HP numbers are from our DynoJet since we didn't always test at competition:

2001: 502 (wings/undertray, tube frame, YZF 600)
2002: 497 (72 HP, wings, beefier tube frame, YZF 600)
2003: 484 (full body, Zexel, 77" wheelbase, F4i tuned by ear at the Silverdome)
2004: 472 (62 HP, body/undertray, hybrid tubeframe/composite panels, ATV diff)
2005: 452 (72 HP, no body, BBS centerlocks, sheet metal uprights)
2006: 447 (70 HP, lighter seat and firewall, 74" wheelbase)
2007: 435 (80 HP, smaller fuel tank, removed 5th/6th gear, lighter uprights, rotors and hubs and lot's of aluminum chips underneath the lathe and mill)
2008: 42? (70" wheelbase, lighter drivetrain but heavier shocks, ARB's and shifting system)

I've been on the team since 2005 and I totally agree with terra_dactile, it's been awesome watching the cars get lighter and faster. Hopefully I'm around to see our car get under 400 lbs with an F4i, much applause to the teams that are able to do it now.

[Pete M]

It may sound like i'm criticising but i'm actually not. I'm more curious about the justifications that teams with a different approach use, particularly those that seem to see weight as an end in itself. Have the teams that have lightened their cars at the expense of power to weight looked at tyre load sensitivity etc to show that they're actually making the car faster? Because if you don't gain much grip from the lower weight, then the lower power to weight would start to hurt you.

In your case, your power to weight will probably be equivalent or better than most of the NA 600 field, so it seems like much less of a compromise. Assuming you get it running reliably and lag free of course.

One question though, what's restrictor lag? It's not something we've experienced, i don't think. I would have thought the restrictor wouldn't have been much of a restriction at typical corner exit speeds. Unless you have a large plenum and even with the restrictor choked it takes ages to fill?

[terra_dactile]

Hey Pete,
With the 2004 R6 we could spin the wheel very easy, inertia was very high, only 2nd and 3rd gear were used during endurance so rpm was not likely very often in high hp range.

2007 car has a very low interia, still can spin the wheels easily, uses all gears of transmission (5), managed to be 1st in Autocross and one of the fastest team in endurance at formula student(prior to tire derimming), when the driver got out of car he complained about lack of engine response and power.
Point being inertia and getting usable power is much more important then the value of HP itself, I would much rather have quick response with a lower Hp value.

From what I have learned in FSAE (my fifth year now), is that no matter what the design you have low hp or not, you need good preparation (2-3 months of tests) and a good driver that is comfortable in the car and you can be as fast as any team.

Sorry to go so far off original topic!

Jude Berthault
ETS FSAE 2003-Current
Team Leader

[VinceL]

Pete,

It's not just about load sensitivity and steady state grip. Mass has an effect on the car's transients as well. People get hung up on power/weight. It's important, but it's not the only ratio you should be watching. Some other useful ones are Cf*Cr/m^2, which is a 'tire to weight' ratio, where the C's are cornering stiffnesses. Another good ratio is wheelbase/radius of gyration.

[Pete M]

Well, without wanting to get into too much of a pointless theoretical argument, there's more to transients than mass too! I realise that mass has many effects on the car's behaviour, as does that mass's distribution through the car (PMI, static weight distribution, cg height). I never claimed that making the car lighter, all things being equal, would make it slower. I was just wondering what info/simulation went into those trade-offs or whether some teams were just going for "as light as possible" and hoping for the best.

Don't get me wrong, I'm not trying to defend heavy cars. I'm just curious, as a member of a team with a relatively heavy car, whether other teams have shown that making the car lighter, even while making some relatively serious compromises, corresponded to a real decrease in lap time. Not in a sim, but on track with a real driver. This isn't a theoretical argument to me, but a real one going on inside our team. Do we stick with the same fundamental package and just try to make it as light as we can, or do we make radical changes that sacrifice other things in the hope that those sacrifices will be outweighed by the advantages?

[flavorPacket]

After doing this a for a while, I'm of the opinion that any reliable and not terribly-designed FSAE car is capable of being a 'fast' car. All you need are good drivers and testing.

I used to think that staying up till 4 every night looking for that last ounce in a bellcrank or ARB mount was useful. Now I realize that a car with no ARB and no bellcranks built in 1/2 the time may vey well be significantly faster.

[terra_dactile]

Pete,
To answer your question, for our team after formula student 2004, we went in with a high Hp heavy car and got our ass kicked by delft and RMIT who had about half our Hp and Delft was about half our mass(125 KG), RMIT(200kgs). We chose as a team to keep the oldest members challenged and on the team to save about 150lbs in one year. No simulations or theoretical caluclation lead us in the risky avenue, I say risky because at that point RMIT had not yet proven that a single could be champions at FSAE EAST (which they did 2 years later) followed by Texas A&M in California with a single as well.

Our goal was to reduce mass, inertia in roll, pitch,yaw and in rotational components., we did not need to do simulation we saw with our eyes what light cars could do at competition. RMIT won the endurance and overall,Delft got second in acceleration.

Our teams goal at that point was more towards winning design events as our dynamics were pretty bad ( bad drivers, lack of reliability, lack of nuts and bolts check sheets etc..)

I stick with the point that any car well tested can win, you just have to choose if you want to learn about testing and car setup or about omtimizing a car part by part with crazy analysis and test benches, either way i am sure you will learn a lot about engineering.

Jude Berthault
ETS FSAE 2003-Current
Team Leader

[Buckingham]

I'm just curious, as a member of a team with a relatively heavy car, whether other teams have shown that making the car lighter, even while making some relatively serious compromises, corresponded to a real decrease in lap time.

The converse is fairly easy to test on last year's car. How much slower do you get by adding 20 lbs?

[VinceL]

I know there is more to transients than mass. I was trying to say that I think the biggest advantage a light car has is in transients rather than in mid corner. Because like you alluded to, the load sensitivity of an FSAE tire is small.

I've watched a shifter kart destroy our FSAE car on a track similar to our shootout track. The kart was so much quicker in the chicanes and slaloms. (I hope I just didn't start another discussion about why karts are faster than FSAE cars http://fsae.com/groupee_common/emoticons/icon_smile.gif )

And yes we have done testing into the advantages of decreasing mass (and other parameters) with an actual driver on an actual track. We've also repeated the tests in computer sims. (It's actually the topic of my final year thesis.) It's not a hard test to perform.

[Steve O]

I know its a couple posts in the past, but first, Pete, I knew your intentions and didn't think you were trying to criticize. Next, in response to your question, maybe its not necessarily poor response due to the restrictor, but I do feel that the 450 is more responsive in general. I will admit that it could just be better intake manifold design but I can't help but think that the smaller demand for air through the restrictor and smaller lighter internals have something to do with it.

As far as making serious compromises, I think the only major compromise we have made is using a smaller motor which, for us anyway, has turned out to not really be a compromise. Using the smaller motor has allowed for a lighter and more compact frame which has saved weight. Using the smaller motor also inspired a completely new frame design last year, which had it flaws, but was overall much better than our previous frame. This year our space frame car before adding in the weight of the turbo system, if we choose that route, is under 350#'s and is very comfortable to drive and much safer than cars of years past. So whether or not the benefit is there I will leave up to debate, but I don't think we have made any serious compromises.

I wish we had the ability to A/B test similar vehicles with different weights, it would be an interesting experiment

Steve

[Pete M]

Fair enough, thanks for the replies.

We've informally tested the weight thing with small amounts of weight and seen no difference in times. It's probably due to how much we're traction limited rather than power limited. Probably should repeat the test more formally though. It's hard to add really large amounts of mass without upsetting the geometry of the mass (particularly CG height and front-rear weight distribution). And adding 100 pounds doesn't entirely let you know what the car would be like if you removed 100 lbs and some power. Because for the 100 lbs test, we aren't adding an even more powerful engine than we have now. So all it'd show you is that we'd be power limited heaps more and slower for it. Whereas making it 100 lbs lighter might also be more power limited than we are now if those 100 lbs came out of the engine. Plus, the load sensitivity of the tyres isn't exactly linear.