Hey,

I just read Claude's answer to a weight question (he wrote in the FSG forum that 180-200kg for a 4 cylinder and 130-150kg for a single would be an appropiate design goal).

And now I'm asking which are the lightest cars for each concept?

I mean:

- single 10inch
- single 13inch
- two cylinder (I don't know if there are a lot of these running) 10/13
- 4 cylinder 10/13 (I only know Ann Arbor with 10inch..)

- Electric 10/13

I know that Delft had super leightweight car some years ago, would this be still "legal"? So that should be the lightest so far.


Would be great to have a list here.

Cheers,

Tom

For the electric cars:

Delft's 2011 car should be the lightest 10" car with 178kg.

Zurich's 2011 car had 181kg in Silverstone with 13". (It's now little bit heavier though )

I'm not so sure for the combustion cars. TU Graz seems always pretty light with their 13", 4 cylinder.

I'm not so sure what you mean with "include drive".

(If you mean "driver". Then no, of course not).


Both weights are the official race weights from FS Silverstone 2011. Without driver but ready to race.

Delft and Penn State were both under 300 lbs in the past few years with their singles. Delft has since been electrified and Penn State went turbo last year, which added weight. GFR was 304 at Michigan this year without aero, I think 350 with. Oklahoma was 331 with an Ape and full active aero (somehow).

For cars on 13's I've heard that someone was low 350's a few years ago, and this past year we had a 360 lb car from Kettering out in Cali.

And I've seen a couple 4 cyls either very close to or under the 400 lb mark.

Yes, these are all without driver.

Oklahoma was very light with their space frame, aero car with 10's
Missouri S&T has been below 420 lbs with a space frame, 13's, aero and a 4 cylinder
SDSM&T was 370 lbs with a space frame, 13's, aero and Ape

Once we have established the lightest car for each concept, it will be interesting to review how each of them went at comp. Especially the Endurance event.

What would be more interesting would be a program that plots results (design, autoX, enduro, fuel) vs weight, for ALL teams, so we can see if there is a trend.

Building the model would be quite easy if that info was included with the official scores. Weight, wheel size, engine size and type, NA vs Turbo vs Superchager, fuel type, and chassis type could all be added.

Wollongong were 188kg (414lb) in 2008 with a spaceframe turbo intercooled 4, on 13's.

That car died in the enduro's due to lack of carbon glueing knowledge.

The following year was 198kg with similar specs to above and we placed 3rd in enduro and overall.

U of Evansville's 2011 competition weight was 351 lbs.... 13" wheels, space frame, single cylinder.

Helsinki 2011: tubular steel spaceframe, 13" alum. wheels, 4cyl NA R6 engine. Includes fuel, oil & all other liquids.

193,5kg or 427lbs FS Silverstone
196kg or 432lbs FSG Hockenheim

Second fastest lap in FSG endurance, 3rd in acceleration, 4th place overall.

Hey all

We ran 312kg electric/13 last year. That's our 3rd gen electric car but the first one that worked. I expect that'd be about your benchmark for heaviest...

We did nearly embarrass Monash during the accel run though. 0.1 sec off and limited to less than half our max power as well courtesy of the scrutineers.

For electric cars the lower end benchmark currently is Delft with 176,8kg/10" and Zürich with 181,9kg/13"

Having the lightest car is like having the highest power output - it doesn't say anything about performance.
As far as I know the lightest car which ever passed tech was from Delft in 06 or 07 with incredible 125kg. But that car never finished an endurance.
I was never part of a team which built a car under 200kg but had the honor to win quite a couple of competitions

Swinburne's 2010 Jap Spec car (spaceframe, 4 cylinder, 13" rims) was 252kg wet.

Definitely on the heavy side but did manage to lap over 1.5sec per lap quicker than anyone else in Japanese enduro. Plus managed a skidpad time of 5.05s

The car was to go on a massive diet until the program got axed by the dean



Matt

Why this continuing obsession with light weight?
There are other design goals which are equally valid and in my opinion correlate more strongly with competition performance.

For instance:

Total distance driven by the car BEFORE the event. (I think we logged about 700 km on our new car this year)

Total distance driven by each driver, in your new car BEFORE the event.

Total distance driven by the car since the last time it broke/overheated/couldn't restart/needed jumper leads immediately before the event.

Variation in times between your drivers in the same events (the best measure of your driver preparation, training and depth)

The difference between your car's simulated performance(using measured metrics) and what it achieves on track. (We like to call this your "Execution" score)

These are the metrics that deliver competition performance. They frequently require the addition of weight to the car, and a shortening of the design cycle. They also make the car faster and more reliable. You learn more about the car, get more feedback from drivers, figure out what is important and come up with more ideas on how to improve the car next time round.

So why are these things so difficult to justify to design judges, and even the teams themselves?
It continues to amaze me!

Scott,

The real measure I am interested in is the "resolution" of weights effect on performance. We know that by simulations a kg is worth about a point (or similar), but it is harder to assess the points value of early finishes or increased reliability, which can sometimes be had at the increase of weight.

We know that practically a 210kg car will have little to no performance disadvantage at comp to a 200kg car. At the same time a 250kg is trumped by a 200kg. From observation I would suggest the weight that makes little difference is in the order of 10-20kg.

I would expect that a team could make a good case for an extra 20kg (4 cylinder car) in design if that weight did actually buy increased running time and reliability. The design wins I was involved with all involved cars carrying a useful 10-20kg extra, so it is not as big an issue to design judges as maybe they state, and students fear. But it is important that the extra weight is justified.

At the start of the year it is worthwhile identifying both the useful and not useful extra weight (as well as easy and difficult weight to remove). My take is that you do not attack the useful weight (i.e. brakes, suspension arms) until most of the useless weight (bodywork, poor load path material) is minimised. Every year I see 220kg+ cars with radical weight savings in critical areas and a lot of fat in others.

Kev

quote:

Originally posted by Scott Wordley:
Total distance driven by the car BEFORE the event. (I think we logged about 700 km on our new car this year)

That is the best rational to use for a "heavy" car, but what is the true effect on real world points and simulated points?

Your car and our car are heavy for what they should be, but when you consider that before the Japanese event, our car completed in excess of 70 endurance events, with the only problem being a half expiring due to excessive life (was design/made in 08 for use that year. Broke in 2011), that's pretty bloody good. We've worn out a set of Avon's and a Goodyears in one "pre comp" testing season. Before that, one or two sets of Hoosiers for the previous season.

What's that old saying, a decent design delivered in time is a lot better than a perfect design delivered late.

But the problem we had with the weight was justifying to people/judges, that the penalty was worth the reliability reward.
You simply can't create pretty graphs and computer simulation pictures that they believe, to show it is worth the reward.

Is our car over engineered?
For a single fsae competition perspective; Yes.
For a overall FSAE project/management and weekend racer perspective (which is ultimately the enjoyment and reward); No

As I don't really know the other cars, here is some about the delft cars:

The Delft (aka lightweight single) concept was based on what would go fast around a formula student track. A high powered gocard would do the trick probably quite well and this is (one of the) reasons for 10" lightweight cars.

The DUT04 was the lightest with ~120kg but the side impact structures were "non present" and what was there was made of tent-poles (so they say).

The last petrol car, DUT10,was 143,1 Kg in Germany.

I do agree that designing a car to be lightweight won't get you any points. Think about what you want to achieve: High straight line speed, fast cornering, quick acceleration, good overall, and think about the requirements for that.

Lighter cars usually break a lot more as well (e.g. DUT09); To finish first, you first need to finish...