Designing an FSAE chassis

[marcush.]

I fully understand your position and tell you what ,a spaceframe is a lot more sexy and apeealing to me than a cardbord monocoque.
ACarbonfibre tub is of course the holy grale but then you could say ..why not use
conified tubes with special crosssections all this in titanium? what a nice challenge ..think about hydroforming ...the story is endless what you could do time and expertise allowing ...
But at the end of the day formula student is allso about finishing your product and competing .so you have to go easy routes as long as they are not compromising your performance .I do not advocate trampling the paths carved out by the hordes of studend before your arrival...but sure it has some reason just why no spaceframe cars are built these days anymore ..apart from the series were it is mandatory...

[madtown77]

..why not use
conified tubes with special crosssections all this in titanium?

To be blunt, because it is against the rules I believe. (titanium anyway, for some very good reasons)

We welded and fabricated almost every piece on the car including throttle body, uprights, frame, differential housing, etc. You learn by doing. If a weld breaks, you just learned that you need to be better at welding it. We had 2 or 3 really competitent students who could weld and 2 or 3 really competitent machinists (myself included). It will take some time but if you can find someone to teach you (faculty advisor, guy down the street at the muffler shop, etc.) it will go by pretty fast. Desperation helps .

In the US, most schools have the facilities to construct most components. In Germany, they have to outsource to sponsers because they have no shop (or any on campus facilities). No idea what the situation in UAE is.

Getting a little off topic guys. I suggest people read a little of the FSAE rulebook on chassis construction before getting too passionate about their pet design ideas .

EDIT: 2011 FSAE rules will be posted on September 1st.

[madtown77]

Lets say you can do it like this:
Start with a welded frame, when you are able to handle this go on and develop a composite chassis.

amen

To do a CF tub requires a lot more preplanning than most EXPERIENCED FSAE TEAMS have the ability to do. I can't even remember the number of times we had to cut off a tab and move something on the frame. With a CF monocoque, that isn't an option. All mounting locations need aluminum billet within the structure to give a mounting point. It's definately not possible for a first year team and we have looked at it my last year there and decided that it would take some development time (IE build a "test car" and the real car with a tube frame at the same time fot he same suspension, etc.).

Again, Michigan State (a good team) missed the 2008 competition because their autoclave and CF sponsor took a crap on them. These guys knew how to build a composite car and look where it got them. Better have hold over someones soul and their autoclave before you even consider going that route.

[marcush.]

how can you allow cf fabrication and rule out titanium...very strange...but rules are rules...

my choice is still the Honeycomb cut and fold monocoque .. it worked for williams ..it will work for FSAE...

[madtown77]

how can you allow cf fabrication and rule out titanium...very strange...but rules are rules...

The reason is because aside from a front impact attenuator, these cars are dependent on their structure for impact attenuation. F1 cars have side and rear crash structures so the chassis itself can be very ridgid. True, CF monocoque is ridgid, but is more likely to absorb energy than a Ti tube frame.

That and welding Ti is tricky.

[marcush.]

how can you allow cf fabrication and rule out titanium...very strange...but rules are rules...

The reason is because aside from a front impact attenuator, these cars are dependent on their structure for impact attenuation. F1 cars have side and rear crash structures so the chassis itself can be very ridgid. True, CF monocoque is ridgid, but is more likely to absorb energy than a Ti tube frame.

That and welding Ti is tricky.

welding Ti is not more tricky than doing a CF tub....infact welding ti is not more tricky than welding stainless .You have to have a gas chamber to do your welding..that might be a bit bigger fot a whole chassis and you will have to make sure to have it completely purged but apart from this ..no difference.. stainless welds will also be alot better if done in a chamber and not only bag purged...

[madtown77]

....infact welding ti is not more tricky than welding stainless .You have to have a gas chamber to do your welding..that might be a bit bigger fot a whole chassis and you will have to make sure to have it completely purged but apart from this ..no difference...

So...its trickier than welding 4130 steel. Again, facilities being what they are at most colleges I don't really see it as practical and weld quality in Ti is harder to attain than in steel. I just don't see the practicality in it for FSAE.

Consider that an "established" team has a budget of around $25,000 a year, it also isn't cost effective. That is unless you are feeling generous marcush?

[marcush.]

you get me totally wrong there.
I´m NOT advocating a titanium spaceframe,and not even a steel one .I don´t think a cf frame is something a group of students can master and surely not for 25K .

But with all the legacy cars going in FSAE it would surely make sense to look into monoposto history and ask yourself why we cannot find any spaceframe chassis
in motorsport apart from those who are specified as such (formula ford for example).So within the rega the use of composite panels is entirely allowed if you are able to demonstrate the capabiliies.

[RacingManiac]

here a few words about F (GRP skin)and M(aluminium skin) honeycomp sandwich board chassis construction..

to me this is a very doable ways of constructing a very stiff and precise structure.
compared to fabricating /welding a spaceframe or doing a CF Tub this looks straightforward ,almost lego-stile car manufacture....very efficient ,almost no special hardware and skill required..proper bonding technique is key challenge ,and a bit of CNC machining of the board,but entirely doable to highest standards.it´s second to cf in weight and dirt cheap....
and to quote mr o´Rourke from Williams :we would not even think of using CF if we did not have to....

http://www.tech.plym.ac.uk/sme/acmc/download/chass.pdf


http://www.grandprix.com/gpe/cref-orobri.html

Been there, done that....

http://www.fsae.utoronto.ca/?page_id=16 ... &gallery=8

4130 jig welded frame with in-house designed carbon fibre/nomex bonded panel with tailored layup for specfic area.

Its easier and less capital spending(no giant 5-axis cut mold), but it is still trickier since our school don't have in house composite facility so we have to drive out to a shop an hour away to do all the composite work.

[marcush.]

here a few words about F (GRP skin)and M(aluminium skin) honeycomp sandwich board chassis construction..

to me this is a very doable ways of constructing a very stiff and precise structure.
compared to fabricating /welding a spaceframe or doing a CF Tub this looks straightforward ,almost lego-stile car manufacture....very efficient ,almost no special hardware and skill required..proper bonding technique is key challenge ,and a bit of CNC machining of the board,but entirely doable to highest standards.it´s second to cf in weight and dirt cheap....
and to quote mr o´Rourke from Williams :we would not even think of using CF if we did not have to....

http://www.tech.plym.ac.uk/sme/acmc/download/chass.pdf


http://www.grandprix.com/gpe/cref-orobri.html

Been there, done that....

http://www.fsae.utoronto.ca/?page_id=16 ... &gallery=8

4130 jig welded frame with in-house designed carbon fibre/nomex bonded panel with tailored layup for specfic area.

Its easier and less capital spending(no giant 5-axis cut mold), but it is still trickier since our school don't have in house composite facility so we have to drive out to a shop an hour away to do all the composite work.

and you had a wet layup ...not yet Resininfusion so debaulking was limited still my honest respect for your achievement as madtown and others said ..one can be surely proud of what they have done ...and of course it can always be done better..such is life you learn as you go.

[RacingManiac]

Yep...infusion was planned but was not really in the card at the time. I think the team later on when they made a full monocoque(and with a different sponsor) might have tried to go that route.

For us the way we did was relatively quick despite the hassle and we still control most of the timing. The later team became largely dependent on sponsor's schedule and as a result they had numerous lengthy delay.

I think in my experience in FSAE practical manufacturing availability is as much of a design constraint if not THE constraint in how the car is designed and built. In our case we basically tries to do as much stuff in house as we can since through different years you've learned that while sponsors are needed, relying on them too much ends up biting you....For us that translate to as much design can be welded and machined on manual(non-CNC) parts as we can, and simpler composite design if needed.

[marcush.]

Yep...infusion was planned but was not really in the card at the time. I think the team later on when they made a full monocoque(and with a different sponsor) might have tried to go that route.

For us the way we did was relatively quick despite the hassle and we still control most of the timing. The later team became largely dependent on sponsor's schedule and as a result they had numerous lengthy delay.

I think in my experience in FSAE practical manufacturing availability is as much of a design constraint if not THE constraint in how the car is designed and built. In our case we basically tries to do as much stuff in house as we can since through different years you've learned that while sponsors are needed, relying on them too much ends up biting you....For us that translate to as much design can be welded and machined on manual(non-CNC) parts as we can, and simpler composite design if needed.

thats the world...not just FSAE.
Get the best result in the shortest time with as much control as possible.
A scenario where you have to first learn how to do something ,buy equipmnet etc ..is surely better than outsourcing to a sponsor who is not prepared to go the extra mile to get things done AND for free...that is begging for morea hit between the legs.
But if there is a possibility to do something to the highest standards with almost no equipment and zero experience there is not much to be discussed.
I wonder why the examples of the m/F-Board do their joining not simply by epoxying aluminium strips and angles in the joint area.. could rivet those in place and you are done..No glassfibre mess..

[mep]

you get me totally wrong there.
I´m NOT advocating a titanium spaceframe,and not even a steel one .I don´t think a cf frame is something a group of students can master and surely not for 25K .

Many established teams can master a composite chassis.
There is no problem with it. Don't underestimate students.
Btw. 25K is to less, we used more than 100K.

[marcush.]

you get me totally wrong there.
I´m NOT advocating a titanium spaceframe,and not even a steel one .I don´t think a cf frame is something a group of students can master and surely not for 25K .

Many established teams can master a composite chassis.
There is no problem with it. Don't underestimate students.
Btw. 25K is to less, we used more than 100K.

can master without outsourcing .. that was my point ...sorry I was not intending to offend someone..

[mx_tifoso]

How/where do the FSAE teams get their funds? It sounds like it isn't cheap.