The first 4WD FSAE Car(s)

[Bob Wright]

This years Aus comp might have one, and we're starting to build our 4wd chassis for 2004 in the next few weeks. We have done a lot of calculations on good points and bad and it seems like you'd really have to stuff up to make it not work at least as good as 2wd.

just wondering if anyones done anything or has any opinions on it?

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Angry Joe]

Sounds like a packaging nightmare but I guess you guys have it figured out.

I'd be worried about the motorcycle clutch and gearbox, which were designed for one driven wheel. Even with 2wd we get more clutch slippage than we'd like. I hope you're not using an early R6 motor, they have a reputation for having weak second gear dogs (which we confirmed when we trashed ours during acceleration tests)

Sounds like an interesting project but I don't envy your drivetrain guys...

Lehigh Formula SAE Alumni
Team Captain 2002-2003

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

[Scott Wordley]

The clutch is one of our biggest worries which is why we asked on the forum a while back about ways to beef up a CBR clutch. Aside from changing the oil regularly and having a spare on hand there doesn;t seems to be much else to do about the issue.

The packaging really wasn't as hard as we thought it would be, but I guess there are hard and easy ways of doing it (as I'm sure you'll see when you compare the different 4WD FSAE cars). It just depends on your commitment and how far outside the square your prepared to think.

In that regard I'm interested to hear how other teams would go about (theoretrically) implementing a 4WD.

Also has any other team in the history of the comp ever tried 4WD? I'm not aware of any...

Regards,

Scott Wordley & Roan Lyddy Meaney
Monash FSAE Wingmen
http://www-personal.monash.edu.au/~fsae

[Sam]

What kind of weight are we talking here gents??

Sam Graham
Engine Group Leader 2003
UQ Racing

[Scott Wordley]

Funny that... everyone always asks "how much more weight?" rather than "how much more traction?"

Anyway we estimate an additional 30kg in driveline alone but expect weight savings in chassis, suspension and wheels. Everything else is pretty much the same weight wise.

How much additional weight do people think is acceptable for 4WD?

Regards,

Scott Wordley & Roan Lyddy Meaney
Monash FSAE Wingmen
http://www-personal.monash.edu.au/~fsae

[Eddie Martin]

I heard that the University of Newcastle was going to have a 4WD at the OZ comp this year. Anybody from newcastle out there to confirm or deny?

Eddie

[Scott Wordley]

I wasn't going to publicly out them or any details of their design, but thats my understanding. Very ambitious for any team let alone a first year car. I had a good chat to the 'Castle boys in Adelaide though and they seem to have design pretty well sorted and the resources to get it build. Good luck to em... I can't wait to see it.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Sam]

On that note, how are the new teams for the Aussie comp comming along? Anyone around from ADFA / Curtin etc..

On the 4wd note, if too much traction is gained off the mark, then the engine is likely to bog down quickly. weight will not help this. It is a vicious circle when engine power is fixed. More traction needs less weight! Perhaps a turby will help low rpm power but that's weight again.

Sam Graham
Engine Group Leader 2003
UQ Racing

[Daves]

I'm guessing 100% more traction. All the weight will be on all of the wheels, but I suspect the place where an all wheel drive car will really shine is acceleration. The problem with rear wheel drive is that you first must have a lot of weight transfer to the back for traction, and then you go forward. However, with all wheel drive, you already have all of the weight on all of the tires.

My bet is faster in acceleration than the average car and slower in skidpad and autocross. Endurance? I don't think it matters. I'm just guessing, though.

[Mark Anderson]

The University of Newcastle will be attempting to construct a AWD vehicle. The reservation of being a 1st year team has worked in our favour, as we are designing the car from scratch, with components specially design for the AWD application. Teams that head towards AWD in the future will have to answer the question that we have already answered. A quick note, you can not adapt a 2WD chassis to a 4WD system, think about it, it requires a total re-engineer of the car from front to back.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Scott Wordley]

Well how's UQ travelling Sam?

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Daves]

Something to think about:

Artic Cat makes a 500 cc ATV with a CVT and all wheel drive. However, it also weighs more than the usual FSAE car and has fewer horsepower.

[Sam]

Give a little get a little eh? http://fsae.com/groupee_common/emoticons/icon_smile.gif
Not too bad mate,

Nothing too revolutionary, Just a weight-loss program, chrom-moly chassis, ally uprights,

We are hoping the Turkey Mk III will be substantially lighter than last years beast (304kg! heaviest car at the comp!!) W

Sam Graham
Engine Group Leader 2003
UQ Racing

[Sam]

Didn't finish my post...

Most of our design is done, our new chassis is getting there. engine hasn't been run yet. The boys are pretty much on an exams hiatus..

Sam Graham
Engine Group Leader 2003
UQ Racing

[clausen]

With some very rough calculations with weight transfer and traction circles, I estimated that you might not want any more than 25% of drive torque at the front to not get power understeer accelerating out of corners.

Just my 2 cents worth

Regards

Paul Clausen
Uni of Adelaide

[Barry]

From what I have looked at so far, you need 3 differentials to make this work well. I have been working on some concepts and designs myself. It would do very well in all events. Much better than RWD.

Barry Lenart
Lawerence Tech

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by dave_s:
I'm guessing 100% more traction. All the weight will be on all of the wheels, but I suspect the place where an all wheel drive car will really shine is _acceleration_. The problem with rear wheel drive is that you first must have a lot of weight transfer to the back for traction, and then you go forward. However, with all wheel drive, you already have all of the weight on all of the tires.
<HR></BLOCKQUOTE>

Too bad our acceleration event starts after the launch.

The highest HP cars are traction limited however, and seems like making the car 'hook' in acceleration is more important than power-to-weight ratio, so you might very well be right.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Denny Trimble]

Launch is still critical in the accel event, because the faster you're going when you enter the lights, the higher your average speed and the quicker your time, all else equal. When they didn't require the transponder to be on the nose, we would try to mount it on the rear of the car if possible, for this reason http://fsae.com/groupee_common/emoticons/icon_wink.gif

You do need a very good engine before 4WD can even be considered. 55RWHP, which we had in '99, just won't produce massive wheelspin on the endurance course.

Best of luck to the 4WD teams, I'm excited to see what you come up with!

University of Washington Formula SAE ('98, '99, '03)

[JCMarshall]

Newcastle boys, do you know what you have got yourself in for. Most first year teams have trouble getting a working 2wd car to the comp let alone a 4wd. I hope it is half way built (rolling chassis at least) to save next semesters grades. Anyway good luck, I hope you do get there, I can't wait to see it.

BTW, you Monash boys do some good work, I'm looking foward to this years car.

We never got that 0.9mm exhaust tube so it's my fault our engine has not hit the dyno yet, how did you guys go.

Pat
UQ Racing

[Jon Prevost]

We figured 12% loss in power going through our drivetrain to the wheels. I'm figuring you'll be using 2 additional diff's which will result in a lot more heat and a lot less torque getting too those front wheels.

, Jon
"Success - it 's what
you do with what you've got." - Woody Hayes
Engine Team

[Scott Wordley]

Thanks Pat,

We did find that stainless, if your still interested I might be able to find out who the supplier was and get you the details. You can contact me off the boards at: scott.wordley@eng.monash.edu.au

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Al]

Pat,

We found that stainless at a company called Atlas Steels. Down here they only had a few metres left and hence we grabbed it all. They are a national company though, so maybe they have a warehouse up your way.

Best of luck finding it, as it certainly isn't easy, but im sure you already know that anyway,

Cheers

Alistair McVean (Monash Uni)

[Engelbert]

I imagine the advantage of 4wd would be coming out of tight corners, not so much launching hard in the accel events etc., as once the car is in motion and the clutch is fully engaged, it would be difficult to acheive wheelspin in a straigh line anyway (even in a 2wd car)...and when launching from a standstill, a 4wd system would have the clutch as a weak point, so might not be very advantagous anyway...

So would the weight increase (with lower peak lateral grip) of the 4wd car, outweigh the increase in out-of-corner acceleration ?

Also the reduction in driveline efficiency would play a factor I assume ?

Plus, those torsen diffs are heavy, so adding 2 more of them to the driveline increases its inertia significantly...

Any comments ? Does anyone have any data in this area ?

Sam.

[Scott Wordley]

Who said we were using torsen diffs? If we had to use three diffs that heavy and with that much inertia we wouldn't even consider 4WD.

Good point on the reduction of peak lateral grip, but it doesn't really apply with our big wings except in the really really slow corners. And thats where the 4WD should prove its worth.

Its quite simple really.

Wings = High Speed traction
4WD = Low Speed traction

What else do you need?

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Engelbert]

So would you run spools or open centres ?

If you ran spools, I could imagine the car wouldnt turn too well (at all?!)...and if you ran open centres, what's the use of 4wd ?

That leaves some form of traction control ? What system would you use ?
Do you have elec. gurus doing their own thing or would you use an off the shelf product ?
Have you guys done any testing in that area (sorry, I dont know if your last car had traction control or not...).
Do you know how much extra weight the 4wd system you would use is ?

Sam.
Its_Boring@hotmail.com

[Scott Wordley]

Sam,

Re read this thread for how much extra it would weigh.

There are a million types of diffs that are not torsens. Most work as good or better and are a hell of a lot lighter. Damned if I know why everyone uses torsens in FSAE...

As for traction control, you only really need that if you have insufficient traction. With 4WD and wings we don;t think that will be the case.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[D Mack - CMT]

Hey Sam, Curtin Uni is going along ok.

Finances are tight as you all may be experiencing but its geting there.

might as well plug the website...
www.cage.curtin.edu.au/~curtinmotorsport (http://www.cage.curtin.edu.au/~curtinmotorsport)

Dusko Mackoski
Curtin Motorsport 2003

[This message was edited by D Mack - CMT on June 20, 2003 at 05:52 AM.]

[Angry Joe]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
There are a million types of diffs that are not torsens. Most work as good or better and are a hell of a lot lighter. Damned if I know why everyone uses torsens in FSAE...
<HR></BLOCKQUOTE>

$300 for FSAE teams http://fsae.com/groupee_common/emoticons/icon_smile.gif

Lehigh Formula SAE Alumni
Team Captain 2002-2003

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

[Bob Wright]

Good point Joe,

But many of those same teams will also spend double that on carbon fibre body work to save a kilo or two? On a kg/$ basis the diff is cheap weight saving.

I think its more a case of people not looking past the tried and true solutions. Which surprises me a bit.

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Mark Anderson]

I agree with the Monash Boys, everyone is using the torsen differentials without looking at possible alternatives. Newcastle University have looked at this problem and has a solutions that allows us to have 3 differentials for the cost of one torsen, have a think about that.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Mark Anderson]

Pat,

As I have mentioned before, the development of AWD systems required complete re-engineering and therefore in many ways Newcastle being a first year team is a benefit because we have nothing and therefore we donot have to adapt last years components (which can not done). When you all go to AWD which you will in time, you will have the same questions to answer as we have. The University of Newcastle have both the funds and resource that other University have not. I is my option that UNRacing has more money and resource then other Universities. Simple because we are a first University don't write us off, remember wollongong in their first year.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Bob Wright]

Yeah, but we thought of 4wd first. http://fsae.com/groupee_common/emoticons/icon_razz.gif

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Alan]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Bob Wright:
But many of those same teams will also spend double that on carbon fibre body work to save a kilo or two? On a kg/$ basis the diff is cheap weight saving.

I think its more a case of people not looking past the tried and true solutions. Which surprises me a bit.

<HR></BLOCKQUOTE>

We've been using the diff out of a Honda 4-wheeler for the past two years without any major problems. Its not cheap but it weighs half as much as the Torsen. We've found it to be a good alternative to the tried and true Torsen.

Kettering University FSAE

[Disco]

[QUOTE]Originally posted by Mark Anderson:
Pat,

When you all go to AWD which you will in time, you will have the same questions to answer as we have. The University of Newcastle have both the funds and resource that other University have not. I is my option that UNRacing has more money and resource then other Universities. Simple because we are a first University don't write us off, remember wollongong in their first year.

Mark,
I don't agree with what your saying. For one, I certainly have not written you off purely because you are a first year team. I'll give any team due credit who is willing to have a crack at FSAE.
Secondly, are you fully aware of every other universities financial position and the resources that both their sponsors and university provides to them?? Such a bold statement, I don't believe I've seen you around RMIT. If you have been here, i'm interested to know what you know about our facilities??
And thirdly, (in my opinion) I don't believe all uni will eventually go to AWD. I still believe that uni's will be running RWD for years to come, purley on the justification that the added complexity was not worth their time.

Kind Reagards
Stephen Price
Project Leader
RMIT Racing 2003

[Dave Riley]

Agreed Steve,

We have changed just about every component on our car for this year, despite the fact we ran pretty well last year. We could have decided on a switch to 4WD if we'd wanted to, and I believe we could have pulled it off. Instead, we've focused our attention in other areas- if nothing else this competition should show you that there's more than one way to attack the problem at hand...

I certainly wouldn't write Newcastle off, having spoken to you guys in Adelaide, I think you've probably tackled the problem of being a first year team very well, although I'd be apprehensive of tackling such a project straight up... full credit for having a crack!

I'd be surprised if anyone outside UWA has any idea of our team resources and facilities, except maybe our friends at Curtin http://fsae.com/groupee_common/emoticons/icon_wink.gif - very nice website!

I think we'll be sticking with RWD for some time yet, given the effort we've invested in other areas of innovation this year.

Cheers
David Riley

Project Manager
UWA Motorsport 03

[Charlie]

Boy, you are sure setting yourself up for a big fall. If you've got the best funding, the best resources, and the best type of vehicle (4wd). You guys should run away with the show! http://fsae.com/groupee_common/emoticons/icon_wink.gif

Try not to be too cocky about things, I'm sure any school will tell you, they learn a LOT at every competition. And if you have the best design bar none, but haven't had experience actually building one of these cars yet, you've still got a tough road ahead. Fun, but tough. http://fsae.com/groupee_common/emoticons/icon_wink.gif Good luck, can't wait to see the car (and Monash's as well), but let your results speak for themselves http://fsae.com/groupee_common/emoticons/icon_smile.gif

As for us all running 4wd 'in time', there is no way. As long as rules don't dictate it, you'll always see different solutions to the formula. There's another thread here, where some people are pretty convinced that light, simple, and small single cylinders are the answer.

As for 4wd, I'm not convinced yet but I'm happy to know we'll get to see the cars in person.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on June 21, 2003 at 10:34 AM.]

[gug]

hiya Mark, dont worry about everybody getting stuck into you on these forums. its not personal, youve just upset people by saying that youve got better resources. but i would love for you to defend yourself here, why do you think that you have better resources? im discovering in my team at the moment that we all have some unique resources, such as free carbon fibre, a mid-sized windtunnel, and 2 workshops outside the uni one.
while you may not be able to get people to post up every resource they have, im sure they will all give you a rough idea of where UNRacing stands if you post up why you think you have better resources.
i hope you do have better resources than us, cause i want to see the most fast and advanced cars at the comp. im one of the people here to learn, not to win. good luck with 4wd!

i am the grand master of procrastination. if i was this good at kung fu, i could kill you with a look.

[eon]

We've been working on a prototype of our next years SAE car..
AWD
adjustable balast
driver adjustable wing
100% traction
anti roll cockpit
good frontal collision protection
300bhp with a top speed of 22mph
adjustable track (well track adjustment actually)
8 gears.. (4 reverse)

and a reversing buzzer!!

http://130.130.24.178/bbs/tractor.jpg

We're working on the aero package in the next month or so .. we're sure we can really tighten up on this lil beuty an keep her under say 30000 pounds!!

eon in the 'gong

[EnricoPalazzo]

Good luck with the 4wd platform, however did you consider other options such as engine mapping? I dont see much benefit going 4wd due to limiting factors like low hp and weak clutches, plus added weight. I am new to this, and still have heaps to learn. What are the options when it comes to tyres and suspension. Obviously launching will come down to a good soft suspension and nice tyres, however soft suspension will hinder cornering speed etc.

R33 with 162rwks

[Sam]

Pissing off the diff is indeed cheap and weight saving.. we are doing just that http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Sam Graham
Engine Group Leader 2003
UQ Racing

[Disco]

[QUOTE]Originally posted by gug:
im discovering in my team at the moment that we all have some unique resources, such as free carbon fibre, a mid-sized windtunnel, and 2 workshops outside the uni one.
QUOTE]

Dear Gug,
I think you'll find that these "unique resources" are not so unique. Sorry http://fsae.com/groupee_common/emoticons/icon_smile.gif

Steve

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by EnricoPalazzo: I dont see much benefit going 4wd due to limiting factors like low hp and weak clutches, plus added weight.<HR></BLOCKQUOTE>
im pretty sure that coming out of a corner you generally have spare traction on the front, and i know that if you put your foot down you will leave lovely little black lines on the road. still think that hp is a problem? if you cant smoke em up coming out of the hairpins, then your engine has some serious problems.
you can beef up the clutch too. speaking of that, you Monash boys find an easy way to do it?

and finally, Disco you have pointed out why i do engineering. my english is too bad for me to do anything else. what i meant was that resources like this feel unique when you first hear about them, but every f-sae team has at least something equivalent.

i am the grand master of procrastination. if i was this good at kung fu, i could kill you with a look.

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Scott Wordley:
Sam,

Re read this thread for how much extra it would weigh.

There are a million types of diffs that are not torsens. Most work as good or better and are a hell of a lot lighter. Damned if I know why everyone uses torsens in FSAE...

As for traction control, you only really need that if you have insufficient traction. With 4WD and wings we don;t think that will be the case.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae<HR></BLOCKQUOTE>

TO SCOTT:

How is a wing supposed to provide downforce when launching off the line ? I'd expect a front wheel (or two) to smoke a bit, and not much else...unless you are using traction control or 3xLSD's....which is it then ? (You didnt answer before)

Sam.

PS. Using a wing hasn't guaranteed victory yet either....

[Matt Gignac]

I think what Scott meant was that 4wd takes care of low-speed traction, with the wings giving traction at speed.

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Scott Wordley:
Wings = High Speed traction
4WD = Low Speed traction
<HR></BLOCKQUOTE>

hehehe, just had to point it out http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Scott Wordley]

Sorry Engle,

We are using three LSDs as you suggest.
The wings are for high speed traction as I mentioned.

I totally agree that a wing will never guarantee victory, and likewise the lack of one will never guarantee defeat. We have found that our wings made our 2002 car faster. We predict that 4wd will make our 2004 car faster. Obviously having a car that is as fast as possible is important due to the dynamic bias in the scoring but it is NOT everything.

Its quite possible that we will find that wings or 4WD may use too much fuel, weigh to much or are too costly($). These are all factors which influence your score via the Fuel Economy Event, Design, Costing etc. This may mean it is advantageous to run a simpler, if slower car. If that is the case then that is what we will do.

The fun part is in trying something new.
The competitive advantage comes if it happens to improve the car in the context of the entire competition.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Fergus Wilson]

I agree with Scott. You need to do what works well for your team, and at the same time perform across the entire competition.

As for resources, we were thinking of entering Stumpy as a second year car. Scott, are those wings still available for hire from the 4th-7th December?

Good luck to those brave enough to try something new, with what ever resources are available!

Regards

Fergus Wilson
Project Manager
UOW Racing 2003

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

[Scott Wordley]

Anything for you Fergus

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Mark Anderson]

My Assumptions where made off listening to the teams report in Adelaide, however I am beginning to believe that not all the teams spoke the truth. In any case I was simple placing my point across that UNRacing (in my opinion) has the resources, sponsors, dollars and technical knowledge to undertake AWD in 2003. I hear alot of talk about extra weight, in a couple of weeks I will release the weight of our car to compare it with the rest of the 2WD cars.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Charlie]

Wow, to have your car finished in a couple weeks is impressive. http://fsae.com/groupee_common/emoticons/icon_smile.gif A 4wd car will probably need lots of testing though so looks like you are on the right track.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on June 23, 2003 at 08:08 PM.]

[Disco]

Mark,
Much can change in a short period of time. Many companies are willing to help with inkind support which really only comes once manufacturing starts. Besides, how can you truly measure how much support a sponsor gives. Many of our sponsors put in time and do things for free that we have no idea how much would cost.

As for teams not telling the truth, do you wish to elaborate?

[Mark Anderson]

Yes many things can happen in a short period of time, however that what good planning should be able to overcome, we believe that we have consider all of the major problems that we could run into and have alternate plans in place, however one can not consider them all. Keeping track of your sponsors input, both in time and goods should be easy if you have a good management software package. We have signed contracts with all of our sponsor outlining the sponsorship deal including time and dollars.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Frank]

Hey Fergus,

I thought you'd be building a new car.. as "stumpy" has already competed in two competitions?

Regards
Frank

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Scott Wordley:
Sorry Engle,

We are using three LSDs as you suggest.
The wings are for high speed traction as I mentioned.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae<HR></BLOCKQUOTE>

Understood! Nice work. Out of curiosity, are you willing to divulge the make of the lsd's you will use ?

Will you drive the front diff via a shaft or chain ? I expect the gearing to be complicated and heavy...nightmare to package (seeing as how its hard enough to package the neccesities, let alone the 'optional extras'!)

Good luck with the 4wd+wings thing. It'd be nice to see a 'complicated' car do well, and interesting to see what real performance gains are to be had using both systems together.

Sam.

[Scott Wordley]

Check out our website to see what diffs we use. We've been using them for 3 years now.

Rather than just tell you how we've done our packaging I'd like a couple of people to first tell me how they'd implement 4WD. There are several ways to go about it what would you choose and why?

PS Our gearing is neither complicated nor heavy. In fact its so easy and obvious I can't believe no one else has tried it.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[ben]

I'd probably turn the engine 90 degrees, run a chain (or gear) transfer box to a centre diff then run composite propshafts to the front and rear diffs.

I'd probably be on the not worth bothering side of the 4WD fence though, but I'm fascinated to see what you guys come up with. Good luck to all of you!

Ben

University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)

[gug]

here is how i would do it (and this is how i am trying to do it). ohlins and yamaha make a hydrualic 2wd system for their wr450f enduro racer.

http://www.motobykz.co.uk/2x2/front_01.gif

its been around since '98 i think, but trying to get any technical info on it is a nightmare. im a bit worried about its power handleing, but it has been run on a yamaha 600tt enduro.
as you could imagine, the hydrualics would do wonders for the packaging. i think we dont even need a diff with this one, if we have one hydrualic motor per front wheel?
anyway, post your thoughts on this one. havent had any time to do some real research into it, so its more an idea than anything at the moment.

oh yeah, if anyone knows a friendly engineer at ohlins, could they tell me?

see this article (http://www.motobykz.co.uk/2x2/WR450F-2-trac.htm) for a bit more info.

- if it isnt coming, you need a bigger tool.

[fsae_alum]

Some ideas on how to do AWD. 2 years ago we laid out an AWD FSAE car... twice. The first attempt centered around a side engine layout closely resembling a side engined FSAE car that Univ of Michigan made but with 3 diffs and a whole bunch of heavy axles and cv joints! The next iteration used the typical FSAE layout but replaced the diff assy with a hydraulic pump that fed 4 small hydraulic motors (one for each wheel). The diff action was done using a pressure sensitive valve system that would direct the most fluid (=power) to the wheel with the most traction. The system even featured a control system to limit the amount of fluid sent to each wheel so that you don't just have it all going to one wheel. In THEORY it would have worked just fine. Too bad it cost $12,000 USD to purchase the pump and motors :rolleyes

In spite of...

[Engelbert]

RE: Hydraulic 2WD.

Ian Drysdale (of Drysdale Engineering - the V8 motorcyle guy) said the pumps and motors are way too heavy and expensive for this application (I spoke to him about 3 years ago on this subject).

He used them on his 2WD motorbike project, which was successful in terms of engineering, but not cost...I don't think you could do it in an FSAE vehicle and still be within the costing rules.

Also, I dont have any data on hand, but I would expect the efficiency of a 4wd hydraulic system to be lower than a chain driven system.

On the other hand, the use of a variable displacement pump would mean no gear changes are needed....

Anyone have any efficiency data for the hydraulic system off the top of their head ?

Sam.

[fsae_alum]

Yeah, the cost was EXTREMELY prohibitive. There would be no way to build the car for under 20K, unless of course you either 1.) lied on the cost report like everybody else suppossedly doesn't do or 2.) discretely omitted stuff from the cost report like everybody else suppossedly doesn't do either http://fsae.com/groupee_common/emoticons/icon_wink.gif. Anyways, that's another pile of poo all together. I can ask the guy today that was heading up the project what he was seeing in terms of efficiency. It wasn't too bad from what I vaguely remember. And you are correct to assume going with a variable displacement pump. He did it so that you COULD (if you chose to) only have the engine run over a certain rpm band or a particular RPM and just vary the displacement of the pump. We always thought it would be weird to see a car accelerating and braking with the engine not changing rpm!! The big problem for us was the unsprung weight that each of the motors added to each wheel. Now THAT was a big problem. I'll get back with you guys later today with numbers on price, efficiency, and weight

In spite of...

[Eric Wort]

Back to the weak clutch subject . . .

We've been running full face kevlar wet clutches in our CBR F4 with stiffer springs for the last two years. We roasted a stock clutch pretty badly during the 2001 competition (it didn't fail until shortly after the competition though). For about $150 its not a bad investment.

The clutch is a little bit harder to actuate, but the benefit of choosing whether the clutch is slipping or not sure seems handy during the acceleration run.

Eric Wort
UIUC Formula SAE (http://dilbert.cen.uiuc.edu/soc/sae/formula/)

[Brett Miller]

Anybody looked at electric motors?

Anyone looked at an entirely electric drive system (gas/M85 engine simply generating power for the electric motors)? This would make mapping you EFI really easy. Intake/exhaust could be optimized for one RPM. Its an idea I have tossed around since seeing the old Chrysler Patriot (correct name?) sports racer that never raced. It was a gas turbine/electric hybrid.

Brett

[gug]

how heavy and big is a 50kw generator? dont know myself. i guess you would have either no diffs (4 electric motors) or 2 diffs (1 motor for back, 1 for front), so the weight would be offset some.
is it possible to store power in some lightweight fashion? you could have the genny charging up some capacitors/battery while braking and cornering, and hit the straight with 100kw on tap.
all the benefits you list could be achieved with a cvt, however. gotta admit, would prefer to run a cvt rather than this whole electric setup.

- if it isnt coming, you need a bigger tool.

[Dan Deussen @ Weber Motor]

Ever heard that when transforming one type of energy to another you have losses?
In this case:

Mechanical -> Electrical -> Mechanical

That are two big losses that in my oppinion you cannot mage up for. Plus I don't think you will have enough fuel make it through Endurance if your engine is running at wide-open throttle and peak power RPM all the time. I am not even gonna talk about the cooling system you would need!
I guess there was a good reason that the Patriot never raced!!!

Daniel Deussen

[fsae_alum]

The fuel consumption was one of the MANY MANY problems associated with the hydraulic setup. I asked the guy about the effeciency and he said that it was around 85%. He said that it was so high because he was running high pressure for the system. I'll get more specs on it.

In spite of...

[Brett Miller]

What about electric drive to just the front wheels and a conventional drive in the back. Set the motors up to get you through the traction limited portion of your acceleration. With the low speeds encountered at FSAE I would think that, IF you could package it right, it would be a rather simple solution to retrofit to an existing car for testing. I think that there is a weight penalty in there but if the car is quicker then isn't that the point? People make the same argument about wings, but at the end of the day if youre lapping quicker than your competitors with your "heavy car" is that wrong?

Warning: Rant below!

I haven't been to the competition since 2000 but it seems to me that in the quest of low mass, the indroduction of new systems (wings, 4WD, etc.) is only taken on by teams that are willing to flirt with or break the "no 500+ pound car will make the design finals" rule. Personally, I think the team that does well witht he off-the-wall design (Brown's suspension design comes to mind) deserves much more credit than the team that continually develops the same car year after year. Yes the infintely developed cars do very well. Maybe thats enough for incoming freshman. For me though the drive to participate was designing and building something new that had never been seen at FSAE. I think my interest would have waned if at the meeting after the competition the leadership for the next year said "were gonna build a new frame, get some new shocks, and play with the alignment a little."

Brett

Brett

[gug]

edit: yikes, 2 people posted just while i was writing this! hot topic! see Dan Deussen's post about running wot and overheating to understand what im on about here.


hmmm, once again, cvt. engine runs at wot and peak power for entire race. of course, most of the people who run them are canadian, so they normally have a problem with the engine freezing, not boiling. http://fsae.com/groupee_common/emoticons/icon_wink.gif
i agree with you about those losses. from the engine to the diff you loose about 3% power, dont know how the diff does but i imagine it would be about the same. for mechanical to electrical back to mechanincal i guess anywhere between 20% and 50% loss (note: very uneducated guess here).

on a rather unconnected topic, how are people getting the power to the front wheels? a chain that runs that far would be a pain (imagine 6 chain tensioners), and a driveshaft feels like an overkill for such a small amount of power.

- if it isnt coming, you need a bigger tool.

[Brett Miller]

If I remember correctly the Patriot didn't race because the rules for the series changed. It was designed as an endurance racer so I think that fuel consumption was an integral design element (probably explains the huge flywheel it had).

Brett

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Plus I don't think you will have enough fuel make it through Endurance if your engine is running at wide-open throttle and peak power RPM all the time. I am not even gonna talk about the cooling system you would need!<HR></BLOCKQUOTE>

Most gasoline/electric hybrid economy cars would run best with a constant rpm gasoline engine. However, the ones that are constant rpm (toyota prius?) do not run at their maximum horsepower rpm. Look at industrial engines -- they run below 2000 rpm. So at competition, you can adjust what rpm your engine would be constantly running at, higher for acceleration and lower for endurance.

Also, you need batteries or capacitors to store the charge, which weigh at least hundreds of pounds. Batteries and electrical power may not even be allowed in the rules, seeing as it is essentially an electric car. Also, there is room for cheating by charging the batteries and capacitors with something else besides the car's engine (like the power cord so conveniently placed behind your trailer in Detroit).

[Lyn Labahn UW-Madison]

I don't mean to burst anyone's bubble on this topic, but there is one tried and true fact of engineering and especially formula SAE, simpler is better. I would love to see a 4wd Formula SAE vehicle, I have thought of methods of doing it myself, but make sure that you weigh the tradeoffs. First of all, it would be a miracle for the system to work well the first, or even second year it is on the car. That is just the nature of the beast with new technologies. You are bound the fabricate the whole thing, and along the way realize a few tweaks that you should implement. You will add many more components that could possibly fail, you will add mass to the vehicle, most likely increase CG height, add cost etc.etc.

So what the heck am I getting at? Personal opinion here, if your goal is to win the FSAE there are very slim chance that something like 4wd is going to be the ticket, at least not for a few years after you make your first
car with it. However, if you goals are focused very far off in the future, or you don't care about winning the competition(think Western Wash's V8) and the engineering challenge is what you desire, then go for it! Heck, if you
have the cajones to roll up to competition with 4wd, I will give you a handshake, a pat on the back, and will spring for a brew at Big Bucks.

Let the conversation continue, I am interested to hear more about what the aussies have up their sleeves....

2002/2003 Team Leader
Best overall average finish of the new millenium http://fsae.com/groupee_common/emoticons/icon_smile.gif

[clausen]

Does anyone remember the Colin Chapman quote on building a faster racing car?

"add lightness and simplify"

Regards

Paul Clausen
Uni of Adelaide

[woollymoof]

Where's the fun in that? esp for a bright eyed bushy tailed young engineer.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Lyn Labahn UW-Madison:
I don't mean to burst anyone's bubble on this topic, but there is one tried and true fact of engineering and especially formula SAE, simpler is better. <HR></BLOCKQUOTE>

That's why you guys ran a single cylinder last year right? http://fsae.com/groupee_common/emoticons/icon_wink.gif Air cooled?

Is 4wd going to work? I'm not convinced yet. But I can't agree that simpler is always better. If you can make something more complicated reliable, it can be very beneficial (if its a benefit, complication in itself isn't what we should be after).

There are lots of complcated racecars that have done well vs. a simplified competition. See Audi R8 Direct Injection Turbocharged. http://fsae.com/groupee_common/emoticons/icon_cool.gif You just have to remember reliability.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Mark Anderson]

I appreciate the convidence in you all, personally I did not become an engineer because it was simple. It sounds as through no major innovations has occurred in FSAE because it is simply to hard. With that mind set, we will never to MARS.

As for UNRacing secerts, you will have to wait to see what we do.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[fsae_alum]

I have turned to the simpler is better side in my limited experience with FSAE. The one clear thing that I learned from the whole competition mess was that if you're going to be innovative, you damn well better have extensive proving and testing to back it up that it is a superior design. No jet powered FSAE cars here. From experience, if you're going to do the innovative thing, make sure you've tested it for years and that you have EVERY popssible scenario and question answered. "Do you have any figures showing that the performance gain is greater than the weight penalty?" "Are these just theoretical calculations or do you have actual track time showing otherwise?" "Can I see that testing data please?" "Can you justify the points gained in the dynamic events versus the points lost in the cost report?" Not to be a person to shoot down innovation but those are the type of questions that the judges WILL ask. Better have the answers and they better be in your favor. On a side note, not all of the times are the judges observations correct or worthwhile. After being chastised by the judges for having a fire suppression system on our car and that it is just a "weight penalty" we were carrying around, I found it very amusing to see 2 cars catch fire later that day and one just about burn to the ground. Thank you, but I'll keep the suppression system. The weight penalty is cheaper than hospital bills from 3rtd degree burns and not to mention a completely destroyed car anyday!!

In spite of...

[Brett Miller]

You "simpler is better" types have a point. The problem is you're not supposed to think like that until you reach upper management. Certainly not supposed to be like that in school for gawd sakes!

I guess I just appreciate the teams that innovate more than the teams focused on simply winning the compettition.

To each his own I guess...

Brett

[fsae_alum]

Brett...I FULLY agree with you that innovation is GREAT. Without it, we'd all still be living in caves throwing spears at our food. Unfortunately, from my experience, the judges don't like innovation unless beyond the shadow of a doubt it can be shown to offer a significant improvement in performance that is justifiable with respect to cost, complexity, and weight. I hate the discouragement of innovation here...I mean after all we're not building cars that only turn left. I appreciate the teams that do the innovative things too...unfortunately most judges do not. Our car had a number of innovative features that we were sure would get us high remarks from the judges...but they didn't. Part of that was as a result of the focus on too much of the innovation and not enough of the fundamentals by us, and the other part of it was as a result of the fact that I got the impression that they just weren't impressed with our innovation. Listed below are the things that we did that we thought set us apart from the typical everyday FSAE competitor. To the right of the innovation is the judges responses (those that we did get).

1.) On board fire suppression system - constant weight penalty, get rid of it

2.) True firewall separating the engine from the fuel cell - Yawn...unnecessary weight.

3.) Second firewall sealing the fuel cell from the cockpit - Uh huh...more unnecessary weight

4.) Harnesses run through frame rails for cleanliness - Why didyou do that?

5.) Miata Torsen Type II diff (VERY easy to get replacement parts with exception of housing, Remember this car is suppossed to be designed for the weekend racer who cant afford custom axles and diffs, also offers better TBR) - WAY too much weight.

6.) Rollover protection fuel cut inertia switch (bank angle sensor) - Right

7.) F4i gauge cluster use (allows for FI diagnostics and low fuel inducator) - Ho hum

8.) Fuel cell foam - Another yawn

9.) Aluminum frame made from 5 high speed CNC milled bulkheads and 1.5" x 1.5" square extruded aluminum tubing (allowed for REALLY, REALLY great frame jigging and alignment, as opposed to eyeball welding brackets to tubing in space) - How much does that damn thing weigh? Are you aware of the fatigue characteristice of aluminum (only for one competition right)?

I'm by no means saying that our car was great and perfect (VERY far from it), but the judges would much rather us skipped on the innovation and made damn sure that that the fundamentals were taken care of first! That completes my novel for tonight!

In spite of...

[Matt Thio]

Are you transfering drive to the front axles via chain drive, and does this imply that your chain guard has to be fabricated from MS plate (3 times the width of the chain) for 1/2 the length of the car?

hope it goes well this year for your team and your reputation on this forum..

[Disco]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Mark Anderson:
It sounds as through no major innovations has occurred in FSAE because it is simply to hard. <HR></BLOCKQUOTE>

I'm sorry Mark, this just sounds like another very broad statement from yourself. PLEASE give me an indication of what you believe constitutes a "major innnovation" http://fsae.com/groupee_common/emoticons/icon_confused.gif? Just because you haven't heard of any, doesn't mean that they haven't happened! Do we consider AWD innovative?

[Mark Anderson]

Major Innovation is a major change this direction of preception of an object. Since you all are valuing the need for indepth testing in which I agree, can any one tell me how many years testing where performed on the first FSAE cars. As for the performance, we will not have data on this until we test, however all I can say is have a look at the performance of the WRX and GTR over comparable size 2WD cars and tell me that the benefits are not there if approach in the correct manner.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Disco]

Could you tell me the engine performance to both those cars as well, or doesn't that matter??

[Dave Riley]

I reckon a small lightweight Lotus Elise or similar will beat a heavy (relatively) WRX or Evo most times round a tight track.

The innovation in the Elise is the way they've taken the basics of tried and true racing design and applied it to a road car. The innovation in the WRX is that they've taken the basics of tried and true rallying design and applied it to a road car. Perhaps we're not comparing like with like, but the analogy isn't too far off the mark with FSAE, I think.

Also, major innovation need not be obvious, like a 4WD system. We'd consider our 03 drivetrain mount, for example, to be a major innovation, but noone's going to start a 5 page thread on that.

Cheers
Dave R

Project Manager
UWA Motorsport 03

[Mark Anderson]

Disco, Engine Performance is an important aspect, however my point is not the better performance of the engines but the cars as a whole package, select any equilvant 2WD and rate it against either of the cars and you can find out yourself which is better the AWD or the 2WD.

Maybe you can tell me how many years of testing was spent on the first 2WD FSAE cars prior to competition

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Mark Anderson:
Maybe you can tell me how many years of testing was spent on the first 2WD FSAE cars prior to competition

<HR></BLOCKQUOTE>

Since that's the 2nd time you've asked, what are you talking about? The very first eyar, when there were about 3 cars? Who knows? Probably very little. What on earth could it have to do with the topic? http://fsae.com/groupee_common/emoticons/icon_confused.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Mark Anderson]

Charlie, it seems as though the forum feels to go to AWD you need to test it for a couple of years, just getting my point across that this did not happen with the two wheel drives. Question, why did you all select two wheel drives to start and not AWD is it becuase it was norm or is the best solution to the problem.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Disco]

You can not make such a comparison until a team has done an AWD. I admire you giving it a go, but what makes you think that AWD is the best solution, with no such evidence available?

[Charlie]

Don't confuse one person's opinion with the 'forum's'. I think any car needs testing to be competitive, you don't need years, but 4wd would add a couple tuning aspects.

You can't compare the very first year of competiton vs. competing against 3rd year design iteration cars. You're probably right, no cars had over a year of testing before the first Aust. competition I'd bet. RIT won, didn't they? http://fsae.com/groupee_common/emoticons/icon_wink.gif


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Question, why did you all select two wheel drives to start and not AWD is it becuase it was norm or is the best solution to the problem.<HR></BLOCKQUOTE>

This is a loaded question, I guess a little bit of both. Obviously we had a baseline car with 2WD so that's a good reason to stick with it. It's guaranteed NOT to be a disadvantage, as no other cars have it. I know for a fact a previous team leader had 4WD on the brain and had a design outline to make it happen, but he never did.

C'mon, your statement is an accusation of ignorance to new ideas, so I'll counter: Did you chose AWD because you can prove it's better, or because you thought it'd be a new gimmick that would be worth doing just to be the first? http://fsae.com/groupee_common/emoticons/icon_wink.gif It goes both ways. http://fsae.com/groupee_common/emoticons/icon_smile.gif

You won't change anyone's mind (especially engineers http://fsae.com/groupee_common/emoticons/icon_razz.gif ) with words, or comparisons to production cars. I'll repeat myself, Good luck, let your results speak for themselves. http://fsae.com/groupee_common/emoticons/icon_smile.gif


-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on June 30, 2003 at 01:49 AM.]

[Disco]

With you all the way on that one Charlie.

[Sam Zimmerman]

If four-wheel-drive is better than RWD, then our 8-wheel-drive car for 2004 will beat you all. Allow me to give you all a sneak peak at our preliminary plans.

http://www.ni-offroad.com/vehicles/argo.jpg

The skid-steering should be a real benefit for the maneuverability and with its amphibious ability, we are praying for a torrential downpour.

If only we could get the skid-pad changed to be run on a six-foot diameter circle, we would have it made. http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

Sam Zimmerman
Vandals Racing
2002-2003 Team Leader

[Dan Deussen @ Weber Motor]

Sorry to bust your bubble Sam, but the rules state: "The vehicle must have
four wheels that are not in a straight line."

Otherwise I am sure there would have been cars with four front wheels already, like there was a car in F1 for a season that kicked everyones ass, before it got banned! http://fsae.com/groupee_common/emoticons/icon_wink.gif

Daniel Deussen

[Big Bird]

It does have four wheels that are not in a straight line. It also has another four...

Some people take things so literally.

Cheers,

Geoff Pearson
RMIT FSAE
Melbourne Australia

[Dan Deussen @ Weber Motor]

Maybe two Schools could enter it together, get double the points for every event and set the new points record with a final score of over 1000 points! http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif http://fsae.com/groupee_common/emoticons/icon_cool.gif http://fsae.com/groupee_common/emoticons/icon_razz.gif http://fsae.com/groupee_common/emoticons/icon_cool.gif

Daniel Deussen

[Mark Anderson]

As for the reasons, you will have to wait until our design presentation etc. We have considered all of the benefits and inefficiencies of the AWD system and in our opinion the benefits out way the inefficiencies. My statement is not an accusation of ignorance, is blindingly obvious that other teams copy other teams ideas, which there is nothing wrong with this, but again, did you choose 2WD because is the best or that it has been done in the past and is reliable, in which case how can you agrue that 2WD is better then AWD.

Anyway look forward to talking to you all in Adelaide where you can evaluate the car first hand

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Disco]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Mark Anderson:
My statement is not an accusation of ignorance, is blindingly obvious that other teams copy other teams ideas, which there is nothing wrong with this, <HR></BLOCKQUOTE>

Just wondering which ideas have other teams copied?

[Sam Zimmerman]

You guys better not be copying our 8-wheel-drive idea! http://fsae.com/groupee_common/emoticons/icon_mad.gif

Sam Zimmerman
Vandals Racing
2002-2003 Team Leader

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Mark Anderson:
Anyway look forward to talking to you all in Adelaide where you can evaluate the car first hand

<HR></BLOCKQUOTE>

Yep me too. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[MercerFSAE C. Burch]

Ah, all-wheel-drive... it just seems so right, doesn't it?

But what really are the advantages and disadvantages of an AWD vehicle, specifically as it relates to FSAE? The idea is that you add in some acceleration capability to the front tires - in situations where the rear tires are not capable of transmitting any more accelerative torque. It is my understanding that the rear tires are so hard to break loose as it is that in anything but first gear, it isn't that big of a problem.

What are the disadvantages, as they relate to FSAE vehicles?

1. Increased weight
2. Increased cost
3. Increased reliability issues (Think -350 points for failing to finish endurance)
4. Increased driveline rotational inertia

Those are the obvious minuses... let me throw in some less obvious ones

5. Decreased acceleration! What? That doesn't make any sense! - Let me explain. With our low-torque engines accompanied by high-grip slick tires, we've got a potentially bad situation for AWD acceleration. You see, when an AWD vehicle is launched properly, even in a powerfull vehicle, such as a 911 Turbo or a Lambo, it is imperative to raise the RPMs way up into "clutch destruction" territory, (where there is plenty of engine power), in order to break the tires free for maximum acceleration. Any less RPMs will result in a bogged-down start. Check your latest Road and Track for an example. I don't believe, (nor can I yet verify), that an FSAE vehicle puts out the kind of power and torque to break free four slick tires. The engine will most likely either bog down or burn the clutch. Either way, acceleration is diminished.

6. Increased power understeer. When the front tires are asked to accelerate as well as turn, the traction circle doesn't allow for maximum cornering power any more. It shifts to a semi-forward, semi-lateral acceleration point of the circle. This is NOT what we want in an FSAE vehicle. We want to get around the corner as quickly as possible and an understeering car hurts this.

I do admire the first year team for taking on an AWD vehicle. I think it is just amazing that they've decided that a normal FSAE car was too simple a task for their first effort, so they designed an AWD one instead! Wow!

Chris
Mercer University - Drive! Motorsports
Coming to an auto-x track near you, May 2004!

[Denny Trimble]

Mark,
I applaud your efforts, going into "uncharted territory" here.

However, I wish you wouldn't take such an condescending tone towards the efforts of other teams.

We for one do a fairly complex lap time simulation, studying the affects of vehicle parameters before we make a final decision. I'm sure other teams are doing it as well, they just may not want to share the specifics.

I'm curious if you could share the added weight to your car of the AWD system. I'll plug it in my simulator and share the results of 2WD vs. AWD if you like.

University of Washington Formula SAE ('98, '99, '03)

[Bob Wright]

can anyone seriously name a disadvantage of a car weighing a bit more when the car has an excess of power anyway? If so, can you tell me how much time is spent on a fsae circuit with available power hooked up in the appropriate direction, vs the amount of time when an excess of power is available and at least 30% of your cars normal reaction force is sitting on undriven wheels (which are not particularly busy making cornering force on corner exit).

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Denny Trimble]

How about all that time when the car is in turning-in and at steady-state cornering? Mass*cg_height/track = weight transfer = reduced grip.

But you're building wings and AWD, aren't you http://fsae.com/groupee_common/emoticons/icon_smile.gif

I think the amount of weight we're chasing may be less relevant than we assume as far as dynamic events are concerned, because driver skill is such a huge variable from one team to the next. We've had drivers with 100lb weight differences end up getting the car around the track with the same lap times... after 6 months of training. The lighter driver had the car a gear higher at the end of a long straight, but the heavier one had better skills in the corners.

Chasing grams is good, but don't forget to develop your car once it's built, and train your drivers all year long!

University of Washington Formula SAE ('98, '99, '03)

[Charlie]

What is steady state? http://fsae.com/groupee_common/emoticons/icon_wink.gif I don't think we've ever seen it.

On the subject of traction, it all depends on gearing! Given the fairly low top speed of our course, you can easily design a car that can take advantage of more grip in acceleration. it just depends how often you are comfortable shifting.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Bob Wright]

More weight makes it easier to get the cg lower and fatter tires still mean that a heavier car can do the same as a lighter one in overpowered situations. driver effort is the only thing that goes up (not by much)

I still want someone to spell out an exact situation where a heavy car and a light car- both with enough power to overide traction have any different response characterists, accelerations or anything. (then for bonus points tell me how often it matters and how much on an fsae circuit)

Good point about shifting more often Charlie, once the tractions there then the next step is looking at more power to use it- I dont know if we'll go peakier in the engine or just flatten out the torque. If this 4wd thing works well, we might have the situation where a turbo starts making more sense.

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Mark Anderson]

I dont mean to sound condescending to other teams. I am not going to give up any of the data that we have gathered. AWD is not as hard as everyone believe if done correct and the car is design as a system rather then individuals components.

I can tell you that then increase in weight is marginal, and will not dampen the suspension characteristics. The sprung mass is increased however the unsprung mass is only increased at the front by about 2%. As for the cost, by a re-evaluation of the components selected and used the cost change is marginal however the 2WD will be less. Our engine power will enable us to break traction with all four wheels, and we are currently clutch may need upgrading we are still testing this.

You also need to consider the power bias that we are using as well as the bias ratios of the differentials, at the moment I will not give this information away as it will lead to answers of other questions that you may have.

The packaging of equipment was not easy, however is not impossible, we have managed to do this without any high spin shafts passing through the drivers compartment. Our wheel base is slightly longer then traditional FSAE cars, which is amazing as our drivers feet is behind front wheels.

This is all the information that I am willing to share with the world, those teams that are associated with UNRacing will have access to futher information in future.

The reasons for AWD is not that UNRacing believes that 2WD is simple, however we believe that AWD is the best solution, only time will tell.

I wish you all good luck, with the design construction and the competition and look forward to meeting you all in Adelaide.

Mark Signing off from AWD forum

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[woollymoof]

Bob, the coefficient of friction of the tyres goes down as the load increases. Proportionally less grip and therefore less cornering power. To overcome this I guess you'd have wider tyres but then there is more rolling resistance. I know its not much.
Brakes would probably go off sooner, if they do go off. Thats all I can think of.

Cheers,

Kirk Veitch
Swinburne University of Technology

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Bob Wright:
I still want someone to spell out an exact situation where a heavy car and a light car- both with enough power to overide traction have any different response characterists, accelerations or anything. (then for bonus points tell me how often it matters and how much on an fsae circuit)
<HR></BLOCKQUOTE>

Skidpad. Or any cornering situation on the track that emulates it. Where you are purely interested in lateral acceleration, a lighter car will be better all else equal. 4 wheels being driven doesn't do anything for the lateral part.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[All Wheeler]

To all concerned, I would like to point out the difference between 4WD and AWD. 4WD has a rigid linkage between the front and rear driven wheels. An all wheel drive has a coupling or centre differential to allow differential action. We are constructing the latter of the two.
A few considerations for those interested. With respect to performance:
I would encourage the champions of rear wheel drive to determine their dynamic weight distribution based off their maximum acceleration, centre of mass, and their static coefficient of friction. Once your gear ratios are in place, determine the output torque at the wheels of the vehicle at various engine speeds and gear ratios (easy in an excel spreadsheet). Determine the optimum vehicle speeds for your gear changes, and then superimpose your torque data in terms of vehicle speed. For each gear ratio work out from your maximum static coefficient of friction, the torque at which wheel slip will occur. Then find the points where the output torque at the wheels exceeds this maximum allowable torque. The initial torque calculations may include transmission losses for those purists out there. If a plot of acceleration is done with the same dynamic weight distribution but using all wheel drive, and rear wheel drive, the advantages should become apparent. If you claim to have dynamic weight distributions so highly biased to the rear that the difference between all wheel drive and rear wheel drive is negligible, your performance on the track would be interesting!
A benefit of this analysis is that the acceleration curve data should indicate the amount of load on the front wheels!
A comment to those who consider costs to be prohibitively expensive. Three differentials would be expensive indeed if they were all Zexel Torsens. This needn't be the case. Also CV joints made or distributed by driveline specialists are rediculously priced. Standard CV's although more bulky can be modified for a much lower cost than purchasing specialised CV's (think about how much of your inner CV length is actually going to be used). Shafts and bearings have a low cost in comparison, and there is not much more that makes up an all wheel drive system. To answer those who asked, yes, we do have higher costs than a rear wheel drive system, however the difference is much less than the difference in price between a MOTEC M4 and an M800.
Extra weight? Not necessarily.
I know of many teams that use the standard Zexel Torsen Centres and make aluminium casings. These units are hard to get below 7kgs. The combined mass of all our differentials should just exceed this. We have more shafts, but consider this. The efficiency of a shaft is based off its kinetic energy storage. Linear kinetic energy for this application is dominant, and as such is a function of the shaft mass. Shaft mass can be cut by almost 75% if a wise selection of material and geometry is made. Be careful not to make the walls too thin and decrease the shafts resistance to buckling. Our total shaft kinetic energy storage slightly exceeds that of a solid steel shaft of 19mm OD if we were to run rear wheel drive. Once again there is more mass, but not enough to discourage us from attempting all wheel drive. Might I make a point on wheel selection. This area of the drivetrain is the biggest consumer of energy. I encourage all teams to look into the kinetic energy storage of a 12in steel rim and a 10in Al rim. Any disadvantages of all wheel drive can be more than compensated for here.
Hope I didn't just open a can of worms. Until next time.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by All Wheeler:
A few considerations for those interested. With respect to performance:
I would encourage the champions of rear wheel drive to determine their dynamic weight distribution based off their maximum acceleration, centre of mass, and their static coefficient of friction. Once your gear ratios are in place, determine the output torque at the wheels of the vehicle at various engine speeds and gear ratios (easy in an excel spreadsheet). Determine the optimum vehicle speeds for your gear changes, and then superimpose your torque data in terms of vehicle speed. For each gear ratio work out from your maximum static coefficient of friction, the torque at which wheel slip will occur. Then find the points where the output torque at the wheels exceeds this maximum allowable torque. The initial torque calculations may include transmission losses for those purists out there. If a plot of acceleration is done with the same dynamic weight distribution but using all wheel drive, and rear wheel drive, the advantages should become apparent. If you claim to have dynamic weight distributions so highly biased to the rear that the difference between all wheel drive and rear wheel drive is negligible, your performance on the track would be interesting!
A benefit of this analysis is that the acceleration curve data should indicate the amount of load on the front wheels!
<HR></BLOCKQUOTE>

True, but that only describes longitudinal benefits. I don't think anyone is doubting that! It's the 'other' forces that may suffer. The balance between the two is the real question. Is the increased longitudinal force big enough to overcome the expense in extra weight and higher CG, higher unsprung, all detrimental to lateral acceleration. Not to mention the packaging comprimises (wheelbase, etc). Obviously you think the benefits outweigh.

One thing I am really unclear on, however. You talk about things your team has designed that are, say 75% lighter. Than what? Also, saying that you can reduce your driveshaft mass to about what a poorly designed 2wd car would have in no way makes AWD any better! Congrats on an efficient design, but nothing compensates for' the ineeficiencies of AWD when it can be applied to a 2WD car just as easily. You can't make an arguement like that.

We don't run solid driveshafts, I assure you.
-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[All Wheeler]

I feel as though the point of this forum has been lost somewhere along the way, with many people mincing words rather than engaging in meaningful correspondence.
I would like to put across my point of view that the major disadvantage of extra weight is reduced economy. Other effects such as lessening of coefficients of friction are very minor and non-linear, therefor difficult to predict. Spring rates etc. are a function of the ratio of sprung mass and unsprung mass and can therefore be compensated for. To suggest that just because a vehicle has heavier shafts "it is poorly designed", is quite a large assumption.

To determine shaft geometry, a program was written that considered the expected load case and fatigue life requirements, then determined a solid shaft dimension. This dimension was then modelled into the program WRT impact loading and a new dimension determined. It was an empirical process that involved an increasing inner diameter, always maintaining a stress lower than the fatigue limit strength. Other outputs of the program were shaft masses, kinetic energies at maximum rated speeds, and frequencies of the first modes of vibration. It was from this program that we determined the 75% weight reduction from a solid shaft and the geometry we are using, in the material that we are using, under the load case we are using.

Is a 1250mm track width and 1800mm wheel base too big?

Our drive system particularly at the front end is very low to the ground. This seems more likely to decrease CG rather than increase it. Remembering that CG is responsible for dynamic weight distribution under acceleration also.

Consider the effects of using a torque sensing centre differential. Under load, torque will be diverted to the slower rotating pair of wheels. Under cornering, this will ALWAYS be the rear pair. Upon coasting through corners, the centre diff will then act much the same as an open differential as it will remove little energy from the system. A torque sensing differential on the front pair of wheels will divert torque to the inside wheel upon cornering, which due to Ackerman will cause understeer if the inside wheel is to slip. An open differential on the front would solve this problem, with any slip on the inside wheel being bridled by the centre differential. The comments a few pages ago about torque steer effects on AWD WRT dynamic weight distribution are quite correct. It is also crucial to ATLEAST match your dynamic weight distribution with your centre diff bias ratio. Kingpin offset must also be considered, along with drivetrain symmetry, and the location of front driveshafts WRT the wheel hubs. After all considerations, there is no reason why our system should perform more poorly than a WELL DESIGNED RWD. Hope I have convinced some that there ARE cornering benifits of AWD.


Doug,
team grunt,
University of Newcastle. :

[Denny Trimble]

Doug,
Sounds like a solid analysis on the driveshafts, and torque distribution.

Don't forget that adding mass below the CG still isn't a good thing. You may be drawn to "reduced CG height", but the rest of the lateral load transfer equation is:
Fllt=mass*cg_height*accel_g's/track

So, mass*cg height is the term we care about. Ballast down low reduces your cg height, but it's still mass above ground so it contributes to load transfer.
One of our '95 suspension guys wanted to try "ground hugging weight" as a strategy... we've learned our lesson since then http://fsae.com/groupee_common/emoticons/icon_smile.gif

Also, don't forget about yaw inertia of the vehicle. Mass*distance_from_cg^2 contributes to this inertia, so wheels and drivetrain parts are relatively large terms here. Anyone remember how many linked turns there were in the autocross event in Detroit?
It was mind boggling... http://fsae.com/groupee_common/emoticons/icon_eek.gif

From what you describe, I think you'll do very well. Your team seems on top of things. Just remember to spend time developing the car once it's built! That's worth more than half your dynamic event score right there...

University of Washington Formula SAE ('98, '99, '03)

[Big Bird]

Crikey, this thread is getting enormous. It seems like everyone else has an opinion on this one, so I'll chuck in my two cents worth as well.

Firstly, in regard to Mark Anderson's question many pages back, yes we did consider 4WD at the beginning of the project, as you do consider all possible solutions to a problem. It was quickly dismissed for reasons that have probably all been mentioned above - weight, cost, added design time, packaging issues, blah blah blah. Our whole design philosophy for this year is to keep it lightweight and simple - anyone who has done a Claude Rouelle seminar will have heard him saying that the more you do the more that can go wrong.

Also personally I didn't like the idea of driving a driveshaft through the 20 degrees of steering required on an FSAE car - what happens to the out-of-axis torque component? I hope you have a nice strong front end, (which leads to another point - the weight cost of a 4WD isn't just in the componentry, it's also in the added structure required to cope with all the different torques and forces being fed into the car.) And remember that with the long wheelbase you Newcastle lads have, you are going to need more steering angle than most of us. (And for the records, I would think that 1250track/1800 wheelbase is getting a little too big - I'd hate to be driving the thing through slaloms).

As for the repeated statement in previous posts about car weight not mattering - well that's certainly going to turn the motor racing world on it's head. Has someone told Adrian Newey this? I can't believe anyone entering this competition could say this with a straight face. Even if your power to weight ratio stays the same, a heavier car will be slower around corners - required grip increases linearly with mass for a given cornering speed (m.v^2/r), whilst the coefficient of friction drops off with load. Therefore lower velocity. Also the car will be worse under braking, (or you will have to build bigger brakes - more mass, even less cornering speed.). I won't go into tyre heating and wear, slower handling response, more driver effort, greater loads on components, etc etc.

The arguments everyone has above about increased grip with 4WD, well structured as they are, relate to longitudinal grip only, and specifically when you are try to accelerate in a forward direction. Circuit Racing also involves rearward (braking) and lateral (cornering accelerations), and in both these cases there are good arguments against 4WD. If you flatly deny any tradeoffs to the judges in your quest for more forward grip, then they will crucify you.

Finally, a few comments in regard to the above. Firstly, I think the comment about people mincing words is way out of line. Most of the previous posts have been very well structured and written, and were in fact what I would consider to be "meaningful Correspondence". An opinion that doesn't agree with the Newcastle doctrine is not wrong, nor meaningless. A first year team that comes into a competition boasting about having better resources than everyone else, and belittling others opinions is something I find a little odd, and something that others I know are finding really offensive.

We all applaud you for trying this 4WD idea, and it seems your understanding of the theory is first rate. But what the "critics" have been trying to explain is that there are other aspects of getting around a track quickly aside from corner exit acceleration and getting the most forward grip. A good design is one that finds a balance between all of the conflicting requirements, not just optimizing for a couple of them. It might be worth at least acknowledging some of my predecessors arguments.

All the best,

Geoff Pearson
RMIT FSAE
Melbourne Australia

[All Wheeler]

The University of Newcastle's Formula SAE team is quite prepared to consider other peoples criticisms of our design philosophy. This has had a crucial role in our design process. Once again (unfortunately) I feel as though our comments have been taken out of context or misinterpreted. The points that we have attempted to make thus far are that: we feel that we can do a good job of designing AWD due to our resources; We have developed evidence in favour of AWD; and that there are many other areas that can offset any disadvantages of AWD. We make no bold statements about being the best, or even better than anyone else. We wish to make no comparison to any other team until we are on the track, as to do anything else would be a big mistake. We do have design concerns as I am sure all teams do.

The chances are, that if you feel as though your input to this forum is "well structured" and meaningful, then it probably is. We make no comment on the structure of correspondence, just the subject matter. Messages posted in regard to the structure of other messages rather than the content, are exactly what I am referring to here. At no point do we suggest that "An opinion that doesn't agree with the Newcastle doctrine is... wrong". We would never belittle others for their opinions (especially those with much more experience than ourselves), but I will stress that many of the points raised about AWD are applicable to rear wheel drive, and yet, comprehensive investigations into these matters have not been mentioned on this forum. Many of our comments from this angle have been taken with offense?
I find this a little odd.
Most reasonable criticisms from this forum have been taken seriously. Any other criticisms of our design philosophy rather than our writing style are welcomed. Interpretations of what we MIGHT have meant from our correspondence are not. It is not the intention of the University of Newcastle's team to boast or offend.

As others have already mentioned, we'll let the cars do the talking on the track.


Doug
Team grunt
University of Newcastl

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by All Wheeler:
I feel as though the point of this forum has been lost somewhere along the way, with many people mincing words rather than engaging in meaningful correspondence.
<HR></BLOCKQUOTE>

Well the problem with internet discussions is people's intentions are easily mis-interpreted. I did not mean to offend anyone, just wanted some clarification, and you did a good job answering the topics I brought up. http://fsae.com/groupee_common/emoticons/icon_smile.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[MikeWaggoner at UW]

There's a good article on 4WD F1 at http://8w.forix.com/4wd69.html
Basically tells of the failure of 4WD in F1 due to extra weight, increased complexity, driver hatred (steering and acceleration very difficult to balance, can't steer w/throttle), and lack of need. Ends with obersvation that a '98 2wd ralleye car beat faster 4wd ralleye cars on paved roads.

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

[Scott Wordley]

Some interesting snippets from that article:

With regards to Paul's comment on Chapman going for lightness and simplicity, also note that he tried 4wd, jet powered, unsprung ground effects cars that were considerably heavier than the competition as he felt they may have been faster. Worthy opportunities to innovate should not be completely ignored, you just have to justify it properly.

From that article:
"The staunchest supporter of 4wd in Europe was Colin Chapman. His love affair began when he replaced Granatelli's cumbersome, home built turbine racer with his Lotus 56 in 1968."

Also:
"In 2-litre guise the (4WD) P67 proved a class act in hillclimbs, however, its superior traction giving Peter Westbury several wins. So why did it return to F1 designers' minds during 1969? Quite simply, it was for the same reason wings and turbine engines were tested: the quest for better grip."

Sounds familiar....

Furthermore:
"In the late sixties the magical 150bhp/litre performance border looked set to be crossed and designers started to worry about finding solutions to transfer all that power onto the road. Traction control didn't yet cross their minds but several other interesting ideas cropped up. In theory, 4WD wasn't a bad idea. Actually, it was a great idea. By more evenly distributing torque over all four wheels there was much less wheel spin to account for, thus allowing for better traction off the line and in cornering."

But keep in mind FSAE is not and never will be F1. What works there will not always work here and vice versa. Which is what make the whole debate so interesting.

A consideration that hasn;t been raised yet. The last 2 (possibly 3... I haven't heard from FStudent) FSAE events have been held under wet weather conditions. A small factor perhaps but imagine our joy if the event were to cop a couple of days of sustained rain? Our drivers won;t even get wet under the wings hehehe....

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Insomniac]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> The last 2 (possibly 3... I haven't heard from FStudent) FSAE events have been held under wet weather conditions. A small factor perhaps but imagine our joy if the event were to cop a couple of days of sustained rain? <HR></BLOCKQUOTE>

We would love it to rain for this years (Australian) event, that might help tip the balance in our favour ... but I doubt that going to happen in Tailem Bends, I'm not sure what the average yearly rainfall is there but I think we'd be really (un)lucky to get any moisture on the track ... oh well. maybe when we go to the US in 2004 http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Scott Wordley]

With your resources why not just put in an order for rain?

hehehe... just kidding obviously.

Regards,

Scott Wordley

http://www-personal.monash.edu.au/~fsae

[Charlie]

That's one thing I hadn't thought about- throttle oversteer. It is the basis of my driving style. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif I would strugle without it. But that's a driver training issue, not necessarily a design problem. Wings require a different driving style too.

It's been said before that understeer kills a FSAE car (because of the tight course). Our 2002 car had a 72in wheelbase, and the only way to get it through the tight corners was with the throttle. The drivers that couldn't do that struggled.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

i applaude you also newcastle,

for being brave, and trying it.

BUT, you had beter get a riggle on..

you should have FINNISHED your chassis by now

Regards,

Frank

[Jimboblofski]

heris a bit of lateral thinking for you all. I have just returned from formula student 2003 and the class 1 bath team had 4wd!!!! yes they seem to have beaten everyone.
They have done it using hydralic motors powered from an extension af the output shaft of the gear box.
when i was talking to them they revealed that their entire drive train wheighed 22kg!

However, they did not run it on the competition as they could not dial out the huge amount of under steer they had. This may be due to the choice of hydralic motors and no front diff. However they did claim to see a 3.7 sec acceleration event!!!!!!

[gug]

i know i'm only running off their website, but bath dont appear to have 4wd on their car:
http://www.bath.ac.uk/mech-eng/en-burt3/car.jpg
unless they have glass driveshafts? http://fsae.com/groupee_common/emoticons/icon_smile.gif according to the website they use carbon fibre actually. and to the rear only.
maybe they were keeping it under wraps? would be a tough car to build, cause its also turbo'd, has ground effects, electronic shift.

i hope it is 4wd, cause they aim to come down to oz. that will be another 4wd car their, to add to UNSW and monash (although they will just be showing their half-built 4wd car off i think? Scott/Roan/Bob this right?) is this all the people running 4wd in the oz comp?

- if it isnt coming, you need a bigger tool.

[This message was edited by gug on July 09, 2003 at 12:33 PM.]

[Insomniac]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> to add to UNSW and monash <HR></BLOCKQUOTE>

UNSW? is there something I dont know, or was that a typo ....

[gug]

typo - it was late and i was drinking. UNRacing/uni newcastle.

- if it isnt coming, you need a bigger tool.

[All Wheeler]

The hydraulic AWD is a very good idea. The only reason we didn't attempt to design one for this year was the level of technical difficulty. Since the power/torque/flow rate relations are a matter of pump geometry, why not bugger the standard transmission off and run the pump straight off the crank? The gear ratios could be controlled with pressure and flow regulators. If you had a control system guru, you'd be one step away from a magnificent CVT. Look forward to seeing this car. Also a little bit frightened. Now I know how you rear wheel drive boys must have felt when you heard about Monash and ourselves http://fsae.com/groupee_common/emoticons/icon_cool.gif(just kidding)
Torque oversteer should still be possible with a well tuned centre differential which prevents the front wheels from spinning. As I mentioned before, through corners the front wheels travel a greater distance. If the centre diff is tuned right, under load rear wheels should enter quasi slip before the front.

Doug
Team grunt
University of Newcastl

[ABanister]

Re: Hydraulic Drive

I realize that I kinda missed the boat on this issue, but I was wondering kind of hydraulic systems people are talking about. I have some experiance with industrial and large mobile hydraulic systems.


I have been thinking about a system like this for a couple of years now, but I'm having a hard time with the weight/packaging. Most variable displacement pumps have electronic control to vary their displacement, is this considered "drive by wire"? I know some pumps do have a manual override, which can be adapted to a throttle linkage.

These are some of the other problems that I've thought of:

- Valving for a limited slip would be heavy
- limited input speed of the pump (bigger power=bigger pump=slower input speed)
- additional oil reservior, cooler, and filter (assuming a closed loop system)
- hydraulic locking when trying to push the car (depending on pump and motor selection)
- plumbing. 5000psi hose isn't light.
- depending on the motors selected a case drain may be needed, which means three hydraulic lines to each pump/motor
- hot oil shuttle
- the time it takes for the swash plate to come back to centre could be a problem under hard braking, because the pressure isn't going to come down to zero instantly, meaning that you're going to be driving into your brakes.
- because the fluid can't freely pass thru the pump, your accelerator becomes speed control, not acceleration control. You can't coast with hydraulics (in theory you shouldn't be coasting on a race track anyhow) so as soon as you come off of the gas the motors are going to see the max pressure in the opposite direction, which means that you are under your designed maximum acceleration... in the opposite direction...

One cool factor is that most variable displacement pumps are bi-directional, which means that you would be able to go just as fast backwards as you would forwards.....



Anyhow, if anyone is interested in carrying on this conversation further, feel free to email me at asbanist@telus.net.


Andrew
University of Calgary

[MikeWaggoner at UW]

It seems like if you're going to the trouble of hydraulic drive you should have a collector and then add t it during braking and use it during acceleration, added complexity aside.

UW FSAE
The views of Mike Waggoner are not necessarily the views of the UW FSAE team.

[MercerFSAE C. Burch]

Steering angle vs wheel angle...

This really doesn't go under this topic, but oh well.

What kind of full-lock wheel steer angle do most teams design for? Is it around 45 or 30deg? I would guess that most teams have a ratio of between 6:1 and 4:1. This would mean that for every 180deg of steering wheel rotation, the front wheels are steered 30 or 45deg.

At full-lock, what is the designed force the driver has to input to keep the wheel turned?

-Chris
Mercer University - Drive! Motorsports
Coming to an Auto-X track near you, May 2004!

[Denny Trimble]

I didn't drive our car in the Autocross event this year (tightest course at competition), but our 30deg on the inside wheel (less on the outside due to ackerman) was sufficient.


Steering force varies with the following parameters:

(mechanical trail + pneumatic trail)*lateral force
caster*scrub radius*steer input*torsional spring rate (weight jacking)
KPI*scrub radius*steer input*front static weight (lifting the front of the car)

(edited to add steer input term)

Hope this helps.

University of Washington Formula SAE ('98, '99, '03)

[This message was edited by Denny Trimble on July 11, 2003 at 12:28 PM.]

[Daves]

Is Newcastle coming to Detroit in 2004? Will there be any AWD teams at Detroit in 2004?

[kleetuz]

I've read through all the posts here and I still don't understand the point of having four wheel drive on a good handling race car, the benefits just don't outweigh the extra weight and reduced cornering performance. More weight, more problems, and more power loss to the wheels. 4wd is good for street cars to be safe in wet and slick conditions or for offroad/rally . For all out racing purposes I don't see any good benefits, even for acceleration purposes since the suspension can be tuned to transfer weight to the rear wheels as necessary, and especially in these types of cars its much more beneficial to focus on things other than straight line performance. Sure an awd car will out perform a comparable 2wd car on dirt but not on pavement.

"No such thing as too much carburetor, just not enough engine."

1988 Mazda Rx-7 Turbo II
- "My engine is smaller than yours."

[Denny Trimble]

Kleetuz,
I wouldn't write off AWD so quickly. Here in the misty Pacific Northwest, the AWD cars clean up at the AutoCross events when it rains. And, it's been known to rain in Detroit in May.

Would a slightly heavier, but 50/50 weight distribution AWD car slalom better than a lighter, 45:55 RWD car? Possibly, only simulation and testing can tell.

Also, you need more than 55% rear weight to put down 75HP on corner exit in the dry. The disadvantage to a 40:60 car is that it might not turn-in as well, from my understanding.

I'm just excited about a relatively large innovation in this asymptotic design competition.

University of Washington Formula SAE ('98, '99, '03)

[PatClarke]

Pasted from the Design Reviews of 'Class 3' at the recent Formula Student event.

"UNIVERSITY OF APPLIED SCIENCES GRAZ: Good innovation design but planned 4WD system with fixed torque split may prove too ambitious. Good understanding and if it achieves reality it may be good."

Just noted here as it is pertinent to this thread

Pat

Rudeness is a weak mans imitation of strength

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As with other all-wheel-drive cars, getting the Lamborghini off the line quickly means holding the engine at 5000 rpm before dumping the clutch. Any lower revs would cause the car to bog at the start line. ~~ from August 2003 Road & Track article Power Trip by Patrick Hong, page 71<HR></BLOCKQUOTE>

[MikeWaggoner at UW]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by dave_s:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As with other all-wheel-drive cars, getting the Lamborghini off the line quickly means holding the engine at 5000 rpm before dumping the clutch. Any lower revs would cause the car to bog at the start line. ~~ from August 2003 Road & Track article Power Trip by Patrick Hong, page 71<HR></BLOCKQUOTE><HR></BLOCKQUOTE>

I'm not sure this is a bad thing. In fsae the main problem with launching is that 'dumping' (I presume they mean releasing the clutch quickly but not sidestepping...) the clutch at a high enough RPM to be in the power often means just spinning the tires. With 4wd you might be able to hook up in the power. I do wonder how much a gearbox designed for a narrow single contact patch will like 4 wide ones...

UW FSAE
The views of Mike Waggoner are not necessarily the views of the UW FSAE team.

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by dave_s:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As with other all-wheel-drive cars, getting the Lamborghini off the line quickly means holding the engine at 5000 rpm before dumping the clutch. Any lower revs would cause the car to bog at the start line. ~~ from August 2003 Road & Track article Power Trip by Patrick Hong, page 71<HR></BLOCKQUOTE><HR></BLOCKQUOTE>

dude, i know what you are trying to say, but you couldnt find any better comparision? f-sae: chicks say "im not seeing you if you are spending all your time on that heap of shit! it doesnt even look good anyway!" lambo: chicks say "im wearing no socks and matching underware".

hopefully one day ill drive a lambo, and then ill tell you if thats what they really do say... *stares off into the distance*

- if it isnt coming, you need a bigger tool.

[All Wheeler]

I'm not aware of Newcastle making any plans to go to the USA next year. We've got alot to digest in the next few months, so try asking us again in December. Our plan at the moment focusses on the immediate concern of the Australasian event. The team for next year looks a little under strength at the moment, and support around here is pinned quite heavily on our success....or lack of it!

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>All-wheel-drive cars have a difficult time launching because they can't get wheelspin and that bogs the engine. With a little dust, or rain, to alter the surface conditions, the Evo (Mitsubishi) can launch at higher rpm and get some wheelspin, resulting in better acceleration times.--Shaun Bailey from August 2003 issue of Road & Track p. 31<HR></BLOCKQUOTE>

[Daves]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Driving the front wheels is an option, but requires a driveshaft to pass through the fuel tank and past the driver to a final-drive unit in front of his feet. Thus far, the added weight and complexity have not yielded a net benefit in a single-seater racing car, as any torque distributed to the front wheels causes understeer in a corner. Indeed, I can observe that 4wd has been successful in competition only where the engine has been mounted in a non-optimal position, i.e., front engine/fwd (Audi) or rear-engine (behind the axle)/rwd (Porsche 959). ~~ FIA Technical Advisor Peter Wright, p. 154 of June 1999 issue of Road & Track <HR></BLOCKQUOTE>

[Jarrod]

approximate engine weight, typical 600cc 4 cyl. - 70 - 80kg
approximate driver weight 70 - 80kg
coincidence?

[All Wheeler]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> I do wonder how
much a gearbox designed for a narrow single contact patch will like 4 wide ones... <HR></BLOCKQUOTE>

The dry weight of a CBR 600 F4 is about 180kg. Wet mass with driver is then likely to be around 280kg. These bikes reach 100km/hr in about the same time as a fsae car with a larger rolling radius and taller gearing. I can't see that we will be loading the gearbox more than what it is designed for. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[gug]

for those bike riders out there, i understand that you never downshift without the clutch? is this because you brake better with the clutch in or is it because the gears dont mesh so well coming down?

i have the feeling that downshifting without the clutch (as many teams do) will screw the gearbox quicker than 4wd. of course, downshifting without the clutch and 4wd could really damage the gearbox i guess, because of that extra rotational inertia and traction. the gears would feel like they are "inbetween a rock and a hard place"

- if it isnt coming, you need a bigger tool.

[Charlie]

In 4 years of downshifting without a clutch, we still haven't seen our first internal transmission problem (knock on wood).

Of course our shifting setup isn't orthodox, but there's nothing too complicated about it either. I guess whoever redesigned it in 2001 is a genius. http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by gug:
for those bike riders out there, i understand that you never downshift without the clutch? is this because you brake better with the clutch in or is it because the gears dont mesh so well coming down?

i have the feeling that downshifting without the clutch (as many teams do) will screw the gearbox quicker than 4wd. of course, downshifting without the clutch and 4wd could really damage the gearbox i guess, because of that extra rotational inertia and traction. the gears would feel like they are "inbetween a rock and a hard place"

- if it isnt coming, you need a bigger tool.<HR></BLOCKQUOTE>

High engine inertia, low traction.

Will lock rear wheel, slide out, and die.

They're currently using slipper clutches in moto gp bikes to reduce compression lock-up, as it is a common problem even if the clutch is used.

Sam.
2001 UQ FSAE

[Mechanicaldan]

The main reason for using the clutch while downshifting on a bike is so you don't lock the rear tire and possibly crash. The harder you brake on a sportbike, the more weight transfered to the front. The rear brakes onmost sportbikes are tiny compared to the front. Some of the new sportbikes are starting to use and come with slipper clutches to prevent rear wheel lockup caused by all the engine braking.

Cyclone Racing
www.cyclone-racing.com/fhome.htm (http://www.cyclone-racing.com/fhome.htm)
Iowa State University
Project Director

[MikeWaggoner at UW]

My '84 Honda VF700 Interceptor had a one way clutch on the rear tire.

[Engelbert]

Dan, thanks for repeating exactly what I said, right after I said it...

(note sarcasm)

Sam.

[Charlie]

Did anybody notice that Dan said the same thing that Sam did?


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

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Ben Beacock]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by dave_s:
Is Newcastle coming to Detroit in 2004? Will there be any AWD teams at Detroit in 2004?<HR></BLOCKQUOTE>

Working on it here. It will be a more 'modern' electronic controlled AWD system, and can be removed very easily if testing doesn't prove its worth(or just for the skidpad event maybe?).

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph

[gug]

hey Ben, any details? what precisely does "more modern" mean, aside from the electronic control?
does electronic control mean variable power split between front and rear? or just on/off sort of thing?
sounds interesting!

- if it isnt coming, you need a bigger tool.

[Ben Beacock]

Its a variable torque transfer unit controlled by a separate ECU and works anywhere from 0:100 to 50:50 front to rear bias. Our current estimates are at about 50lbs of extra weight for the complete AWD system and could be less depending on how much time we can manage. Almost all of that weight will be fairly low, however raising the drivers legs counteracts some of that.

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph

[Charlie]

Do you really think the skidpad event is where a 4WD system will really shine? Seems to me, that is where the system would be the least effective (most penalty).

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[clausen]

I think he means that they could remove it for the skidpad event.

Regards

Paul Clausen
Uni of Adelaide

[Mark Anderson]

I thought that you could not make changes to the drive system once the car was Scrutinized, this would mean that you would have to do all the events in AWD.

Ben I am keen to see how you tackled the problem of getting the drive to the front.

Hope everyone's car is coming along, see you all at the track.

UNRacing
Team Director - 2003
University of Newcastle
email: mark.j.anderson@studentmail.newcastle.edu.au

[Big Bird]

Interesting point Mark.

I looked in the rules and it said that you can't make modifications that affect the "power transfer system" after scrutineering. I'd wonder if a driver control that enabled selection between 2WD and 4WD would in fact be a "modification that affects the power transfer system".

My argument would be something along the lines that when we change gear, we actively engage and disengage gears to get the drive characteristics that we want, so why would driver 2WD/4WD selection be any different?? Alternatively, even in normal operation, sometimes certain wheels aren't getting any torque input, so a little driver control of the torque input to the front wheels isn't anything particularly radical.

Of course, if Ben meant they were just going to unbolt all the 4WD bits when they didn't want them, then that would be illegal. But I think there could be ways around it.

I think a mail to your friendly tech advisor would be in order. Mr Suddenlee, any advice??

Cheers,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Break it.

[Charlie]

Anything driver adjustable is fine! Modifications involve mechanical changes to the system, not turning something on and off. As long as you aren't removing something (less mass) or replacing something, as far as I'm concerned anything goes.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Ben Beacock]

Aha, i hadn't looked into the legality of changing the power transfer system between events. I wonder if this is a safety related rule somehow? I'm just curious what this rule is meant to discourage. I'm not too concerned about the on/off aspects of the AWD unit though(very much part of its capability), since it is part of the 'power transfer system' and won't be mechanically modified.

At any rate, it will still be removable during testing so that we can prove the benefit of AWD by comparing times between the full system and the equivalently lighter 2WD. Of course, this is not a 'true' comparison because there will be a few compromises to accomodate the front differential, mostly the height of the driver's legs. However, this may be offset by the use of a triangular front and rear frame (much like the rear of wollongong's frame) that should increase stiffness.

As for the drive to the front, our preliminary designs figure a very long driveshaft from the AWD unit to the diff which is offset to the driver's right

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ben Beacock:
Its a variable torque transfer unit controlled by a separate ECU and works anywhere from 0:100 to 50:50 front to rear bias.

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph<HR></BLOCKQUOTE>

the rule: <BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> 3.7.3 Modifications and Repairs
Modifications to the car are not allowed after the inspection and
engineering judging except as noted below. This includes modifications
that affect the available gear ratios, power transfer-system, or safety. The
removal of body panels for weight reduction is not allowed. Adjustments
(e.g., tire pressure, brake bias, suspension adjustments, wing angle, and
chain or belt tension) are allowed to the car after the start of the
performance events. <HR></BLOCKQUOTE>

variable torque transfer means that its most definetly not a modification.

- if it isnt coming, you need a bigger tool.

[GIJoeCam]

First of all, hat's off for even attempting it. Nothing wrong with trying something new and innovative. That's part of the theory behind the competition to begin with.

However, keep in mind the that this is not only a dynamic competition, but an overall engineering competition as well. As most here probably are, I'm curious to see the execution. I, along with my team, debated the merits of 2wd vs. 4wd/awd and came to some different conclusions. As someone mentioned earlier, there will be some tough questions that need to be answered in order to justify the system. Make no mistake, DATA, DATA, AND MORE DATA will be needed to convince the judges of the justification for the system. That's what's cool about FSAE... within the confines of the rules, you can do whatever you want with the car... you simply have to be able to justify it. Keep in mind that the target market of the vehicle is the "weekend autocross racer." You need to justify everything to address the needs of THAT customer, not just the needs of your teem on a cold weekend in Detroit, MI.

That being said, good luck, and I look forward to seeing it there this year!

Oh, and IMHO, if we get the snowfall like we did in '02, you guys have got the competition locked up!

-Joe

2002 LTU FSAE Co-Leader
2002 LTU FSAE Brake System Engineer
Inaugural 2002 Road and Track FSAE Triathalon Champions!

[Axle_Greece]

I was thinking of this myself, with two hydraulic motors for the front wheels, and perhaps an accumulator. I wouldn't power the front wheels except in and out of turns, and wait till the accumulator had built up pressure. Then, you have about five seconds of kickin' boost to zoom your little tail down a straightaway or two. The question would be, however, do the rules allow for an accumulator to be pressurized before the start of a race? If so, you could just let the engine sit there and run, building up pressure, and then blow everyone away in the accelertion event. The only problem that I see with it is hydraulic line losses, and the relative inefficiency of hydraulic motors when compared to direct driveshafts.

The problem with a prop shaft is you'd have to drill a hole in your pilot and have a removable center section, so the shaft could be run up the middle of the car, or else you'd have to provide additional space under the car, raising the center of gravity of the whole bit.

To ease routing of your driveshafts, it would be entirely possible to run a flexible driveshaft, similar to what is used on dremel rotary tools. Run your hydraulic motors outboard of the frame, in between the upper and lower control arms, then use a flexible shaft to drive the wheels. I am assuming you wouldn't want to split your power 50/50, so something like 80/20 (rear/front) would help minimize total system losses, while still helping a great deal in traction and acceleration, IF an accumulator could be used. With the accumulator, that extra 20 hp to the front wheels would be PURE EXTRA power, except the engine would have to charge it up (and the system could be set up to only operate the pump while at negative omega prime's - rmp's ramping down)

The other option for AWD is electric, but again, you have a question of price and can the batteries be charged prior to the competition? It would be unfair to drive up in an electric vehicle with a briggs and stratton 10 horsepower 10 Kw generator on the back as a sorry excuse for a powertrain, with the batteries juiced up (lithium polymer?) and ready to tear everyone a new one. U could easily have a 300 horsepower beast that would kill everyone in competition, but perhaps get smoked in statics. Also, you'd have to worry about throttle by wire restrictions. There's no throttle on the engine, really, so it would be a full electronic control. I think the best bet is to go rear wheel drive, and to get the car set up as cleanly as possible, mechanically and aerodynamically, then stick with a proven design, tweak, and train your drivers.

one more note... the flex shafts could be allowed to torque over on themselves, like a watch spring, so when you lock the hydraulic motor, the shaft twists, and stores up energy from the wheels, and helps to brake, spinning the motor at some point and generating useful pressure to a secondary accumulator?

Orion

"They say time is of the essence... give me some and maybe i'll get the essence!"

[JCMarshall]

I have just read through most of this thread for the first time since I posted this message in June.

"Most first year teams have trouble getting a working 2wd car to the comp let alone a 4wd. I hope it is half way built (rolling chassis at least) to save next semesters grades."

So Mark Anderson of Newcastle Uni, after being a total f**king tool last year, then turning up to the Aussi comp with a car that nobody envied, where to with the AWD idea?

Do you think you should have listned to those who had infinatly more experence in FSAE than yourself.


Go back and read a few of your comments to refresh your memory if you need to.

Pat.

[Big Bird]

Completely uncalled for JCMarshall. These forums are for some civilized discussion and sharing of ideas, not for personal insult and ridicule.

Not everyone was a fan of the AWD concept, myself included. We all had our chance to offer opinions earlier in the year. But the fact of the matter is that these guys went ahead with the project and came damn close to getting the thing done. More power to them.

You don't need much of a spine to hide behind these forums and say "I told you so". The Newcastle guys put their heart and soul into their car this year, and in the spirit of the comp they showed a level of initiative and innovation equal to the best teams there. The last thing they need or deserve are your smug insults.

There is a function on these forums to edit your previous posts. I suggest you use it.

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[PatClarke]

WOW, JC Marshall, as Big Bird said, totally uncalled for, and imho unnecessary on a good natured Forum like this. I have made my feelings clear on the learning experience at NU earlier in the thread.
Just so there is NO MISUNDERSTANDING, the signature "Pat" at the end of JCMarshalls post has NOTHING to do with me!!! I have not and never would say "Told you so"!
And if I sound Pi**ed off, you are da*n right I am!
You can discuss this with me in person next time I am in Brisbane ......That's if some other of your team mates haven't kicked your butt before then!
PDR

The older I get, the faster I was.

[A Reinke]

you know what i haven't had in a while?

...Big League Chew

[ben]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JCMarshall:
I have just read through most of this thread for the first time since I posted this message in June.

"Most first year teams have trouble getting a working 2wd car to the comp let alone a 4wd. I hope it is half way built (rolling chassis at least) to save next semesters grades."

So Mark Anderson of Newcastle Uni, after being a total f**king tool last year, then turning up to the Aussi comp with a car that nobody envied, where to with the AWD idea?

Do you think you should have listned to those who had infinatly more experence in FSAE than yourself.


Go back and read a few of your comments to refresh your memory if you need to.

Pat.<HR></BLOCKQUOTE>

No need dude, no need.

Yeah, I think many of us agree in general terms about the validity of developing a 4WD car in the first year, if at all.

However, this competition is about learning. With all due respect to GT for example, the Newcastle guys probably learnt more than many teams like GT who turn out very similar cars each year.

This year at Birmingham we did a development job on our 2002 car and it was good (3rd fastest enduro lap 8th overall, 3rd overall after statics).

For 2004 we are doing a completely new car, new engine, new chassis construction. Our lecturer is having kittens because he thinks it will be unreliable and late.

I suspect he is right on the first count, I won't sleep for a month to prove him wrong on the second. What I can tell you for sure is that I've learnt more in 3 months than the whole of last season.

This competition is about learning. In Detroit 139 teams 'lose' in your terms. If that's all it's about for you, you'll be very diappointed.

Ben

University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)

[Brent Howard]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Yeah, I think many of us agree in general terms about the validity of developing a 4WD car in the first year, if at all.
<HR></BLOCKQUOTE>

I have to say I think Mark Anderson was very correct when he said that being a first year team was an advantage to developing 4WD. As he said, a 4WD car has to be completly redesigned from scratch. I don't see why experimenting with new concepts to FSAE is seen as a bad thing, I think that this is the entire point of the competition.

Without being at the FSAE-A competition, I think that Newcastles car failure to run dynamic events was not due in whole to having a 4WD car. How many 2WD cars don't run every year in Detroit, or fail fairly quickly? FSAE is a huge commitment and many times the amount of work is underestimated, especially by people new to FSAE. I really hope that Newcastle gets their car running and continues to build 4WD cars for future. It's much more interesting to see a variety of cars rather than 140 carbon copies of the same design.

Brent

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

[ben]

Fair point.

All I meant to say that was even if many of us thought that, it in no way invalidates Newcastle's approach.

Ben

University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)

[Frank]

Disclaimer:

The previous post by "JC Marshall" aka "Patrick Doody" DOES NOT reflect the views of UQ Racing

Personally Patrick, I think that was a dumb call, if only you were at the comp with our "first car"..

Maybe you could show a little more sportsmanship in this forum

Frank

[This message was edited by Frank on February 08, 2004 at 11:33 AM.]

[darienphoenix]

Damn this is an old topic.

Just to rekindle the debate, are there any AWD sytems currently in development or being used in FSAE? And what happened with Newcastle's car in the 04 comp?

[Homemade WRX]

Guelph seems to have had good luck with theirs...been running AWD since 04 if I recall correctly.

[Steve Yao]

As I recall, Guelph has run AWD successfully on 2004-2005 and went back to RWD in 2006...though I was not at Detroit.

[drivetrainUW-Platt]

Originally posted by SEY:
As I recall, Guelph has run AWD successfully on 2004-2005 and went back to RWD in 2006...though I was not at Detroit.

I dont think they were at Detroit this year...

[Griff]

Guelph ran AWD in 2003-2004 and again in 2004-2005. They didn't go to the competition in 2006, but are working on a 2WD car for 2007.