I believe your side impact structure needs another tube parallel to the ground 300mm to 350mm from the ground

I'm afraid Teemu is right.
The engineering process is tires, suspension, engine, drivetrain, chassis. In that order and as Pat Clarke put it the chassis is only there to hold all the bits together.

Some additional hints from me:
* The minimum angle between main-hoop-braces and main hoop may be as low as 30˚, use that to your advantage.
* Insert braces over the engine to increase stiffness.
* Pay attention to ergenomics, especially seat-angle.
* Don't forget to add mounting-points for all the kit.
* Pay attention to the new rules (No bracing loads through engine, templates)

I'm aware the side impact structure need modifacation. Found that out right after I uploaded the photo.

In terms of suspension, I know we will need negative camber gain when under jounce, and I know we would like the roll center as close to the cg as possible.

The following pic are the two different designs which would provide us with camber gain.


"A" shows the standard unequal length control arms, while "B" shows a modified version which I've seen many FSAE cars run. Design "B" is much easier to make because it's 2 less bends to put in our front hoop and the width is constant.

Still debating whcih style to go with. I'm leaning towards "B" for simplicity (First year team and all, well...since 1992).

I'll keep working on it and check out the tire thread too.

There are a lot of opinions when it comes to positioning the roll center so make sure you do a bit of research before you commit to having the roll center at the CG.

For a first year car you could look at having a geometry that has minimal roll centre movement. This would make the handling really predictable for the drivers so its easier to drive and set up the rest of the suspension.

I think you will find that 'A' puts your roll center no where near the CG, that is of course if thats where you want it I also agree with the guys above, not sure I would be making the suspension fit the already designed chassis

Here's just a pic my friend made. Our vehicle probably won't look anything like the TU Graz car, but its a motivating picture nonetheless

Motivating indeed !!!!!! If Barber sponsors us that would be uber_awesome.

We will most likely be running a Yamaha R6 engine as my roommate rides one and he will wake up some morning to find his engine missing.

-Shaun

Just a small update:

Contacted a couple potential sponsors that we will try and meet over spring break. Should be exciting. I won't divulge too much info on who yet because it's still a little too early to be sure.

However, we did get approval from our senior project professor, so our team is official. However, he said he would only approve 1 SAE project, so no SJSU Baja for 2009.

Hello Joey, as many said before this experience will change your lives. Good luck and enjoy!

Here are some links I think you may find useful:

FSAE Rules and important documents

Equipment Suppliers

FSAE Resources

Official Formula SAE Forums

Pat's Corner Articles

This last one I recommend you read it chronologically starting from the earliest articles.

Hope it helps!

quote:

In terms of suspension, I know we will need negative camber gain when under jounce, and I know we would like the roll center as close to the cg as possible.

Oh yea? Why?

quote:

Originally posted by exFSAE:

quote:

In terms of suspension, I know we will need negative camber gain when under jounce, and I know we would like the roll center as close to the cg as possible.

Oh yea? Why?

After further investigation, I would like to retract my previous statement.

Carroll Smith's books are on their way my friend!

quote:

Originally posted by Pennyman:

quote:

Originally posted by exFSAE:

quote:

In terms of suspension, I know we will need negative camber gain when under jounce, and I know we would like the roll center as close to the cg as possible.

Oh yea? Why?

After further investigation, I would like to retract my previous statement.

Carroll Smith's books are on their way my friend!

Ideally i would like the roll centre of our car to be at the same position as the CG, but only because i would like the CG to be on the ground.

As for negitive camber gain in jounce again its only an advantage because we're not living in this ideal world, not really an advantage under braking though yeah.

Another item of advice, since you guys are so early on in the design stage...

Make your CAD model accurate. The right tube thicknesses, material properties, I would go as far as adding simple solids with the right densities for oil, fuel, water. Hose as well. Rubber hose = heavy. At some point you will want to know an expected weight, CG height, moments of inertia, etc. It is so much easier to just have it calculated automagically by a computer than to set up all sorts of crazy swing setups to try to measure it.

A parts spreadsheet wouldn't be a terrible idea either. Keep track of everything. Every part, how much it weighs, how much it costs, where you got it, an XYZ location.. if you don't want to go down to the nut and bolt level on your CAD model then at least include it in a spreadsheet and get its impact that way. One fastener doesnt weigh much. Hundreds do. For that matter, standardize as much as possible. For example I see no reason to use anything larger than 1/4" hardware anywhere in the suspension, and no need for more than 1 or 2 lengths.

Having that kind of information is priceless for suspension design, simulation, and being able to identify areas of the car you can slash weight or cost from.

It's hard to convince a team to do that sort of thing sometimes.. but the details matter. This way you don't get surprised by having an outrageously heavy car with some absurd mass distribution.

Be smart. Understand your loads and materials well, and design to the limit. As a first year car this may be difficult, but once you know what you're doing, assuming your stiffness goals are met having a 1.2 FOS is more than adequate. 20% over expected max load is enormous.

On the note of details and percentages.. you'd be amazed what a small difference makes. Suppose you have a 1 lb part and shave an ounce off. ~5%. Doesn't seem like much. Do that all over the car..

A 460lb car that's 5% lighter is now 437lb. That's a lot. If you watch racing.. suppose you have a 1:16 lap around Monaco. 5% slower is 3.8 seconds off the pace. At the Bahrain GP this morning, pole was set by a margin of 0.027s (and I recall a year or two ago Kimi taking a pole by 0.002s). This morning's quali results.. difference between 1st and 10th was 2.019s, or 2% off pace. FSAE is nowhere near that close on a lot of things, but even the accel event..

4.500s is a slow time. 5% quicker brings you to 4.275 (pretty decent), and 5% quicker than that is 4.061 (a top time). 5% more engine torque on most of these cars is only ~2 ft-lb.

Or for a much more real example.. think of beer with 5% more ABV!

Just sayin. The small stuff counts in a big way.

quote:

Originally posted by mangel83:
Hello Joey, as many said before this experience will change your lives. Good luck and enjoy!

Here are some links I think you may find useful:

LINKS...

This last one I recommend you read it chronologically starting from the earliest articles.

Hope it helps!

Those links are all great! Thanks for the help.

It's an interesting thing learning about the history of FSAE at SJSU. The team that was here in 1991/1992 got 5th place in the nation, which I find incredible. Yet the engineering department is pretty much oblivious to the fact that they did so well and had such a great thing going. Sadly, the project adviser (teacher) passed away in 2004, so I think we will be dedicating our vehicle to him.

For a new team and even for older teams, my own experience shows the best time to save weight is in the initial design stage when you're working out the overall vehicle dimensions and propulsion. After that, you will be risking more in return for less weight savings. Speed holes will save ounces at best, but building a 60" wheelbase 46" track car will save quite a few pounds.

As the saying goes, to finish first, you must first finish. For a first year team, weight will be the least of your problems. The performance of an FSAE car can be thought of as proportional to reliability^2. Not only does a reliable car actually finish endurance, but it also grants the team precious test time, gives the team a chance to make improvements as competition approaches as opposed to chasing down gremlins, and also goes a long way towards improving the general morale and physical health of the team.

The Grumman Aircraft motto of "Keep it Simple, Stupid" is especially applicable here. It may be very tempting to build your own steering wheel or CNC machine a brake pedal. Save those projects for another year. By the time you're getting in line for endurance, you won't give a hoot how optimized your intake is. Instead you'll just be praying that everything holds together for the next 22 klicks.

In short, just focus on building a simple, rugged car.

quote:

Originally posted by Ecks:
For a new team and even for older teams, my own experience shows the best time to save weight is in the initial design stage when you're working out the overall vehicle dimensions and propulsion. After that, you will be risking more in return for less weight savings. Speed holes will save ounces at best, but building a 60" wheelbase 46" track car will save quite a few pounds.

As the saying goes, to finish first, you must first finish. For a first year team, weight will be the least of your problems. The performance of an FSAE car can be thought of as proportional to reliability^2. Not only does a reliable car actually finish endurance, but it also grants the team precious test time, gives the team a chance to make improvements as competition approaches as opposed to chasing down gremlins, and also goes a long way towards improving the general morale and physical health of the team.

The Grumman Aircraft motto of "Keep it Simple, Stupid" is especially applicable here. It may be very tempting to build your own steering wheel or CNC machine a brake pedal. Save those projects for another year. By the time you're getting in line for endurance, you won't give a hoot how optimized your intake is. Instead you'll just be praying that everything holds together for the next 22 klicks.

In short, just focus on building a simple, rugged car.

I was browsing a Road&Track magazine and came across their annual FSAE rundown. I took the measurements of wheelbase and track width of all the vehicles listed, and the ratio of width to length is fairly constant; between 71 and 77%(apart from U of Tx at Arlington with 66%).

With a 60" wheelbase, 77% of that is 46.2" for width, so that's pretty constant with what I found.

I think we might be a tad over 60" for wheelbase, probably closer to 65" like Tx A&M or Cornell (66" and 64" respectively).

We're currently trying to figure out if we want a live or dead front axle (I'm partial to stub axles in the front, i.e. 1st gen MR2). I like the way Berkeley used VW hubs and axles, which is also an option, as are the MR2 or 1st gen miata parts. Checking out the junkyards has helped me figure out what seems to work or what doesn't.

Hey, I just wanted to take this time to plug a sponsor and help you out with a great supplier! Take a look at AED motorsport, they will get you great deals and can supply you with stuff from 4130 tubing to rod ends/sphericals, to plumbing. Call or e-mail Dave over there.

On another note, just wanted to mention once again to focus on your suspension first... in my first year design I ended up focusing my suspension on what my chassis should look like instead of the other way around... it helps to think of the chassis minimally during suspension design, except of course for the parts that need to be there by the rules.

Another note, watch out for those Baja guys ... this was supposed to be drilled in a straight line... we had a baja guy do it.

This message has been edited. Last edited by: Steve O,

Just a small update on how we're doing!

We were incredibly blessed to have recruited a valuable new member who's currently going for his MBA at SJSU. He helped organize MSOE's 2005 team, and was their engine team capitan as well.

We currently have about 20 members showing up to weekly meetings, we have several sponsors lined up and more on the way.

About 10 of us or so will be going to the FSAE-West competition in a couple weeks to observe and learn as much as we can about what the judges are looking for as well as take note of interesting designs. Hope to run into a few of you down there!

Joey

Skip Barber - Really? Who has been on this forum for a while?
When Jim Russell sponsored FSAE Carroll and I would laugh at the piss poor driving (his words) after all that hard work, no cone was safe in Auburn Hills.

I am still at JRRDS so E mail me rklyver@jimrussellusa.com and we'll try to help you as much as FSAE Rules will allow.

quote:

In short, just focus on building a simple, rugged car.

Didn't Colin Chapman once say something about every part having at least 3 functions?

Simplicity = lightness.