rear spoiler

[jaggi]

anyone know about the correct positionning of a rear spoiler?
in particular the effects of the airflow over the body and how they can contribute or not to downforce

???
anyone

[jaggi]

anyone know about the correct positionning of a rear spoiler?
in particular the effects of the airflow over the body and how they can contribute or not to downforce

???
anyone

[jack]

could you ask a more general question? http://fsae.com/groupee_common/emoticons/icon_wink.gif

[js10coastr]

the answer is 5

[fade]

bout yeay high oughtta do http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Patrick W. Crane]

it really coms down to the kingpin angle and the weight of your shoes.

[MikeWaggoner at UW]

The should be placed wherever they're most effective. If you have have laminar attachment going over your trunk and it's creating a low pressure area over it, you may get less lift with a spoiler at the top of the rear window. On the other hand, you may be trying to reduce drag resulting from laminar attachment at the rear of the car, and the spoiler should be placed at the rear. In some cases, they should be placed at the middle of the window. See beetle turbo.

[EgyptianMagician]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MikeWaggoner at UW:
The should be placed wherever they're most effective. If you have have laminar attachment going over your trunk..... <HR></BLOCKQUOTE>

AHH CRAP! I KNEW we forgot something in the design of our car ... the TRUNK !

Back to the drawing board ...

[jaggi]

ok perhaps i can be more specific...

i am currently doing a feasibilty project at brunel into the use of aero aids on our FSAE car.

it has just come to my attention that the positioning of the rear wing in relation to the car can have a significant effect

is there something that i can read that will give me some insight? perhaps someone here can give me an insight

i have just been considering running the exhaust over the wing. any comments on that?

and the correct answer is 8 actually, dont you know anything.

and yes, we too have overlooked the trunk in our car designs, the next one will not only have a trunk, but also 7 drinks holders and a 24v cigarettle lighter, for that extra performance when you need a light.

[Denny Trimble]

jaggi,
The tradeoffs and analysis can be endless. Higher rear wings may get better airflow, but then the car has a higher CG which is more of a penalty (especially at low speed when downforce is minimal). The weight of your wings is part of that tradeoff. As for the routing of exhaust over downforce elements, what happens to the aero balance of the car in mid-corner if the driver drops the throttle?

[EgyptianMagician]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by jaggi:
ok perhaps i can be more specific...

i am currently doing a feasibilty project at brunel into the use of aero aids on our FSAE car.

it has just come to my attention that the positioning of the rear wing in relation to the car can have a significant effect

is there something that i can read that will give me some insight? perhaps someone here can give me an insight

i have just been considering running the exhaust over the wing. any comments on that?

and the correct answer is 8 actually, dont you know anything.

and yes, we too have overlooked the trunk in our car designs, the next one will not only have a trunk, but also 7 drinks holders and a 24v cigarettle lighter, for that extra performance when you need a light. <HR></BLOCKQUOTE>

Well, speaking from a computer engineering and formula 1 fan, point of view (so just ignore me now)

I have asked around countless times about wing, aero, etc...

These guys (http://www.formulaford.info/cgi-local/navigate.pl?public/FFORD/carspecs.html) go much faster than us, I'm pretty sure they can corner just as hard etc (someone correct me if I'm wrong) and, please observe the lack of wings, front or back.

I've been told repeatedly by some aero guys that at our speeds, it's not about the wings, and chances are they could just increase drag, or, best case provide SOME downforce and an extra location of sponsor logos. Put your efforts into suspension, steering, tires, and of course you need the power.

Yes I know that one of the cars that won FSAE (Aussie?) once or twice, had a huge-ass rear spoiler, but, well I'm not qualified to comment on why, but I don't think it had to do with the big-ass spoiler.

Anyway, might as well re-ignite the debate (or check the thread histories) but I'm gonna side with that at 60Mph straightline speed and and average of speeds of 35Mph, it's not going to make or break your car, as opposed to the F1 boys who will either be on or off the track depending on the wing configs, and in some cases I think adding the wings will hinder performance ... again I'm not "mechanically qualified" to answer (whatever that means).

My 8 cents.

Now off to pester the boys to design a trunk ...

[syoung]

You'd certainly benefit from mounting a rear wing (assunming you have a front one too) way out behind the rear wheels, as it ould create a better moment arm. However, rules say no-can-do!

FFord is not a great example - it's essentially a one-make series, at least insofar as the rules state "no wings". It's kinda like pointing to an F1 car and saying powered ground-effect is useless.

[Patrick W. Crane]

Make a car with wings "Just for the fun of it" then drive it around an autocross, then take you previous non aero car, drive ti around the same track. compare... now change the track and do it again... eventually i think it will become apparent that certain tracks benifit one or the other. So if you know what the competition courss is going to be like, you will know if you should add wings. I don't really think there is any way around it, you have to test it.

[EgyptianMagician]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by syoung:
You'd certainly benefit from mounting a rear wing (assunming you have a front one too) way out behind the rear wheels, as it ould create a better moment arm. However, rules say no-can-do!

FFord is not a great example - it's essentially a one-make series, at least insofar as the rules state "no wings". It's kinda like pointing to an F1 car and saying powered ground-effect is useless. <HR></BLOCKQUOTE>

Well that does make sense, I didn't think of it that way, just assumed that 'they didn't need to have wings'.

Anyway, thanks for the info !

[GTmule]

Of course, putting wings hanging way out back is great, adds more DF to the rear....and takes it away at the front. Of course, you could ass a moment arm at the front, and then it'd all balance out, and it'd be pointless (except MABYE some cleaner air). I'm in the school of though that says, for an SAE car, the time you'd spend on wings, you'd be best off spending getting the susp geomery right, or testing/tuning. Sensible wings WOULD make an FF faster, though, because they run road courses with highspeed turns, assuming you don't add too much drag.

[jaggi]

i sort of have to spend my time doing research on the application of downorce to FSAE cars, i'm doing my thesis on it.

as for the wing being useless, i disagree, i have already seen that wings can provide significant downforce even at low speed. i spoke to some guys at UMR and it seems they were quite unscientific about there aerofoil designs. im hoping with a little CFD and theory i can come up with a feasible usefull wing.

and if i finish that then im gonna make one with a cup holder.

any books or journels, articles you could suggest? not on cup holders.

[GTmule]

www.mulsannescorner.com, (http://www.mulsannescorner.com,) then find wherever it says "required reading" on there, that'd be a start.

[HardCore]

Kimmy, I've got one word for you:

CFD, wind tunnel and extensive testing.

As to effectiveness - refer to Monash '03 car, autocross winner and therefore the fastest SAE car in the southern hemisphere. Oh and it had some phat ass wings.

Big wings - more than just static downforce.

[Joel Miller]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GTmule:
Of course, putting wings hanging way out back is great, adds more DF to the rear....and takes it away at the front. Of course, you could ass a moment arm at the front, and then it'd all balance out, and it'd be pointless (except MABYE some cleaner air). <HR></BLOCKQUOTE>

Very true, but aero FSAE cars tend to be front wing limited, so placing the rear wing further toward the rear probably wouldn't help anyway. For a car with ~50:50 weight distribution, spend more time optimising the front wing then design the rear to achieve aerodynamic balance.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GTmule:
...the time you'd spend on wings, you'd be best off spending getting the susp geomery right, or testing/tuning. <HR></BLOCKQUOTE>

Without aerodynamics, there is a maximum amount of grip that you can get out of tyres, and how close you get to this is affected by suspension geometry and tuning. The only practical way to increase beyond this is through aerodynamic downforce. I think if the FSAE rules stay as they are, wings will become features of all the fastest teams (especially on the new FSAE-A track).

Yes, FSAE is a low speed event, and thus aerodynamic forces are modest. At 50kph, winged teams might expect 50kg of downforce - useless in most forms of motorsport, but significant for cars that weigh ~270kg with a driver. Do the calculations and make then decide if you think the gain is worth the resources. Of course, wings won't help your fuel economy score, but that is what compromise is all about.

[GTmule]

Well, I agree with all of that, but most modestly sized/budgeted teams don't have an unlimited supply of man-hours or money. IMO, this means the teams can either have a WELL sorted chassis/susp, or a WELL sorted Aero setup, but probabally not both. Of course for the large teams, this isn't an issue.

A perfect parallel to real motorsport, really (see Ferarri in F1, Audi in sportscar, etc.

I happen think something should be done is FSAE to make teams at smaller schools (or schools with smaller engineering programs) able to better compete (maningful cost limitations, etc?)

When the larger teams are able to afford multiple channels of Data aquisition, have acess to hours and hours of processor time for CFD/FEA/Adams, lots of tires for testing, a few blown engines diring engine development, etc, etc, it'l really make it impossible for a smaller team at mabye a more rural school to win (think Montanna or somewhere), and that sucks, in my opinion.

I guess I digressed a bit, and I often do, but I guess the point is, for ahuge team, sure, go for the wings, but they serve as, at best a crutch, until you have a fully sorted suspension and chassis. At worst they're just dead weight.

[Cement Legs]

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

When the larger teams are able to afford multiple channels of Data aquisition, have acess to hours and hours of processor time for CFD/FEA/Adams, lots of tires for testing, a few blown engines diring engine development, etc, etc, it'l really make it impossible for a smaller team at mabye a more rural school to win (think Montanna or somewhere), and that sucks, in my opinion.

<HR></BLOCKQUOTE>

I would agree. It would be nice if the organizers at FSAE would formulate some type of recognition for teams with low resources available to them, who still produce competitive cars. In some cases it may be more of an achievement for a team to finish 40th than it is for Cornell to win http://fsae.com/groupee_common/emoticons/icon_wink.gif.

Cheers

[GTmule]

Yeah, the same holds true for alot of the teams on the East side of the pond, I imagine, trying to keep up with the big American schools who have huge student bodies, and tons of money to throw around, not to mention a sometimes larger potential base of sponsorship.

Of course, to get any decent driveline/chassis bits (GKN, Quaife, Hewland, Titan, etc) we've gotta buy 'em from over there, and the dollar is in the toilet.

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by jaggi:
i spoke to some guys at UMR and it seems they were quite unscientific about there aerofoil designs.
<HR></BLOCKQUOTE>

You must have talked to the wrong people, there has been quite a bit of computer analysis and wind tunnel testing on our wings.

[Joel Miller]

GTmule: I hear your argument about team resources, and this will always be a problem in FSAE. On the other hand, a rule that cannot be policed is a bad rule. ATM, FSAE competition is not only about design, manufacture and management, but also about obtaining resources.
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GTmule:
[Wings] serve as, at best a crutch, until you have a fully sorted suspension and chassis. At worst they're just dead weight. <HR></BLOCKQUOTE>
Is acting as a "crutch" necessarily a bad thing? I think teams should make decisions based upon what will give them the best result, and this will be different for every team. Depending on availability of resources and expertise, getting wings might have bigger gains than spending big bucks on DAQ systems (for example). Of course, adding wings to an already fast car will have far greater gains than adding them to a slow car...

Jaggi: Have you read the Joseph Katz books?

If your wing doesn't make your car faster, it can make an excellent park bench...

[Amos]

Having a greater moment arm on the rear wing would be great to get the balance, but then again mounting it would not doubt be a problem like it is with the front - you'd have to start triangulating members to avoid bending etc.

With respect to the usefulness and drivability of a car with wings i can comment on.
Our car that we competed with at SAE-A on the weekend i had driven a little without wings on skidpads prior to the event.
The first time i actually drove the car with wings was on the skidpad during our run.
Having been the ultimate pessimist towards wings prior to this i was shocked to find that the car could be pushed a lot further than before. Had i practiced the skidpad maybe once or twice prior to the comp with wings i firmly beleive we could've placed first rather than second. But hey if we all had a year of testing im sure we could all do a lot better.

Side note - Congrats to the gong for the victory, Auckland for being good allround blokes and bringing such a professional car in their first year, Birmingham and Monash for giving us stuff. Cheers to all at the event!!

[Big Bird]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Cement Legs:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GTmule:

When the larger teams are able to afford multiple channels of Data aquisition, have acess to hours and hours of processor time for CFD/FEA/Adams, lots of tires for testing, a few blown engines diring engine development, etc, etc, it'l really make it impossible for a smaller team at mabye a more rural school to win (think Montanna or somewhere), and that sucks, in my opinion.

<HR></BLOCKQUOTE>

I would agree. It would be nice if the organizers at FSAE would formulate some type of recognition for teams with low resources available to them, who still produce competitive cars. In some cases it may be more of an achievement for a team to finish 40th than it is for Cornell to win http://fsae.com/groupee_common/emoticons/icon_wink.gif.

Cheers <HR></BLOCKQUOTE>

I'm not a big fan of tiered results systems. The "winners" of the lesser classes are pretty well arbitrary - depending on who makes the rules and where the line in the sand is drawn.

From what I can see down here where the world is all upside down, it is not necessarily the "well resourced" or supposedly "big" teams that are kicking butt. Wollongong is not a big engineering uni, but has achieved success through the sheer hard work and dedication of its team members. And if I may recognize the efforts of my team mates, we certainly are not swimming in cash from our uni, nor do we have a huge team. But we are getting up near the pointy end of the comp through huge numbers of manhours and a professional attitude to attracting/maintaining sponsors.

While you are sitting around telling yourself that a team like Cornell is invincible, you will never beat them. The sad thing is that you can....

Cheers,

[GTmule]

I don't mean it like All that, it was more of a general statement. Obviously there are exceptions, and congrats to yall, and other, for making it work, but each situation is different, and that's what it's all about. But us at schools without all the crazy resources are definately starting back a step or two, to be sure.

[Denny Trimble]

That step-or-two is all the more motivation. Stop feeling down about where your team has started, and start planning to take out the top teams. There's no better feeling than to surpass all expectations, based entirely on your team's brilliant engineering and excruciating dedication.

On the topic of Cornell, they thoroughly dominated in 2004. I thanked them for the show, they were amazing. But Geoff is right, they can be beaten. There's nothing stopping your from out-engineering and out-executing Cornell. So get a map of the US, and put a thumb tack on Ithaca, NY. Not as an enemy, but as the kings, to be dethroned. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Now back to designing, I've got to figure out how to hide my lateral force rockets in the sidepods...

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GTmule:
Yeah, the same holds true for alot of the teams on the East side of the pond, I imagine, trying to keep up with the big American schools who have huge student bodies, and tons of money to throw around, not to mention a sometimes larger potential base of sponsorship. <HR></BLOCKQUOTE>

well, adelaide has a population of 1 million people. the next nearest city is 800km away. since our project only allows us to recruit from 4th year engineers, we have about 120 people we can recruit from.

but there is no way i would agree to penalising the bigger teams. i believe that we can compete with anyone. our car depends upon more than how much money is thrown at it or how many resources.

[Eddie Martin]

GTmule, your comments are a bit misplaced. Being a big or small uni with lots or no cash doesn't really make a difference.

We here at Wollongong have about 200 people involved in mechanical engineering across the whole uni including undergrads, postgrads and professors at best, but the number is probably closer to 150. Wollongong has a population of about 150000 people.

The resources your team has are what the team makes for themselves. I don't want to sound arrogant but it seems to me that you are setting yourself up for failure by putting excuses in the way. Your team can finish at the top of the points table, it can have a fast and reliable car, it can have a decent sized budget if you make it happen.

[clausen]

Just to add to Eddie's comments. Claude Rouelle's answer to similar grizzles was "Does Ferrari have more money because they win, or do they win because they have more money?"

But then again Claude also told me we wouldn't win with a DeDion suspension http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Cement Legs]

In my comments I never implied a tierd competition or penalizing big budget teams. I guess I thought it would be nice to have a side award based on those merrits. Something like the Bling Bling award.