Aero mode?

[Brokenrider]

Hi guys

I'm Jaehyun mo ; Captin of Kookmin univ. FSAE team
We particitated in 2009 FSAE West, and I'm fully impressed by Aero cars. So After this compettition, We Tested Wing and Underbody tunnel with CFD. and also installed Wing and tunnell to our 2009car, than We get extra lateral acceleration; 0.1g at under 50km/h
But I still have mistrust.
Why can't Aerocars Win the comppetition??

[Brokenrider]

Hi guys

I'm Jaehyun mo ; Captin of Kookmin univ. FSAE team
We particitated in 2009 FSAE West, and I'm fully impressed by Aero cars. So After this compettition, We Tested Wing and Underbody tunnel with CFD. and also installed Wing and tunnell to our 2009car, than We get extra lateral acceleration; 0.1g at under 50km/h
But I still have mistrust.
Why can't Aerocars Win the comppetition??

[MH]

There's not enough wind at the competition. And don't forget thet Coriolis effect.

cheers!
MH

[TPeterson]

Jaehyun,

I think you are forgetting something. RIT ran aero in California last year...and won.

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brokenrider:
Hi guys

I'm Jaehyun mo ; Captin of Kookmin univ. FSAE team
We particitated in 2009 FSAE West, and I'm fully impressed by Aero cars. So After this compettition, We Tested Wing and Underbody tunnel with CFD. and also installed Wing and tunnell to our 2009car, than We get extra lateral acceleration; 0.1g at under 50km/h
But I still have mistrust.
Why can't Aerocars Win the comppetition?? </div></BLOCKQUOTE>

Because even if you have the best car, it doesn't mean much.

[RenM]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TPeterson:
Jaehyun,

I think you are forgetting something. RIT ran aero in California last year...and won. </div></BLOCKQUOTE>

I guess they didnt win because they had aero but they won even though they had aero.

[MH]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TPeterson:
Jaehyun,

I think you are forgetting something. RIT ran aero in California last year...and won. </div></BLOCKQUOTE>

Yes... and 28th in Germany with all the top teams present.

[Bobby Doyle]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MH:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TPeterson:
Jaehyun,

I think you are forgetting something. RIT ran aero in California last year...and won. </div></BLOCKQUOTE>

Yes... and 28th in Germany with all the top teams present. </div></BLOCKQUOTE>

Funny you put it with such condescending undertones...didn't RIT fail to finish endurance? Last time I checked, the caliber of your opponents does not determine whether you finish endurance. http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[MH]

Just look at the rest of their scores on dynamics in FSG09. It really doesn't show any advantage of having an aero package.

My point is that winning a competition isn't any proof at all. You have to look at the level of competition as well.

Saying you win a competition because an aero package is inaccurate to say the least.

Perhaps I should have explained that a bit more http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Bobby Doyle]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MH:
My point is that winning a competition isn't any proof at all. </div></BLOCKQUOTE>

I agree.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MH:
You have to look at the level of competition as well. </div></BLOCKQUOTE>

You have to look at more than that. Track speeds and layouts are different which discredits the comparison you are trying to make. A car that I would design for FSAE-West would look much different than a car I would design for FSG. It seems you are trying to say (without actually saying it) that FSAE-West has inferior teams. I would just quit the comparison altogether because it is impossible to make a case for or against aero using this example.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MH:
Saying you win a competition because an aero package is inaccurate to say the least. </div></BLOCKQUOTE>

No one said that.


To the OP...if you are competing at FSAE-West and/or SCCA-style tracks where there are higher track speeds then aero MAY be worth it. You have to make the decision taking into account the performance gain v.s. resource investment. If you don't have the extra money and people to invest into a project like aero then your resources would probably net bigger performance gains elsewhere.

[Zac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MH:
Just look at the rest of their scores on dynamics in FSG09. It really doesn't show any advantage of having an aero package.

My point is that winning a competition isn't any proof at all. You have to look at the level of competition as well.

Saying you win a competition because an aero package is inaccurate to say the least.

Perhaps I should have explained that a bit more http://fsae.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>

You could also look at their dynamic scores at East this year. They were fairly competitive with a strong TU Graz car in the autocross, and they (along with S&T) lapped the field during the endurance race. RIT is a strong team that ran into some bad luck at FS Germany, home of the 500+ pound carbon fiber monocoque.

Aero is kind of the red-headed step child of FSAE.I think it's tough to deny that given a more open track layout, that a car with an aero package will be faster than a car without one. Of course, what you have to decide is whether or not that improvement in lap time is worth the other performance trade-offs (increased fuel consumption for example) and use of resources.

But I think too many people get wrapped up in the competition part of FSAE and not the educational. If your objective is to win the competition, aero may or may not be something you want to consider. On the other hand, if you just want to learn about how to design an aero package, I can't think of a better application.

[Pennyman]

Aero packages on FSAE cars take 2 things that every other system requires:

time and manpower

If your team has a lot of both, then I would say an aero package is worth investigating.

If your car and drivers need as much testing as possible, then perhaps the time is better spent finishing the car sooner and developing driver skill and vehicle reliability.

my 2c

[The Neck]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Saying you win a competition because an aero package is inaccurate to say the least. </div></BLOCKQUOTE>

Yeah, Definitely didn't say RIT won because of aero, homeslice. The original question was....

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why can't Aerocars Win the comppetition?? </div></BLOCKQUOTE>

...Which was answered by the fact that RIT won FSAE West 09, and had aero, not that they won because of it.

[J_poo]

How is that that a car with a CF monocoque can even way 500 lbs? Is it just a lump of resin or what.

It seems as though somewhere you are missing the point of CF. The only reason a CF monocoque is sweet is the possibility of a 30-35lbs chassis without being a wet noodle. The weight savings of switching would drop us to approximately 390lbs that is with wings and a coefficient of lift above 2.

[Bemo]

You really think that saving weight is the only reason for a monocoque?

[MH]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by The Neck:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Saying you win a competition because an aero package is inaccurate to say the least. </div></BLOCKQUOTE>

Yeah, Definitely didn't say RIT won because of aero, homeslice. The original question was....

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why can't Aerocars Win the comppetition?? </div></BLOCKQUOTE>

...Which was answered by the fact that RIT won FSAE West 09, and had aero, not that they won because of it. </div></BLOCKQUOTE>

Let's recap, shall we?

The original question of our good friend Jaehyun has clearly to do with winning the competition with an aero package advantage. Clearly he is impressed with the extra lateral g's etc.

So you can interpret his question as: How come aero cars don't win competitions, even though they should have (in his mind) a clear aero advantage.

Enter our friend from RIT saying: my dear friend Jaehyun, don't forget RIT won Cali WITH an aero package.
Now maybe I'm a nutjob, but isn't that at least implying RIT won Cali because of the aero package?

Sorry if I sounded condescending, but we have to be honest here. There is a HUGE difference in the level of competition between various events around the world. FS Germany is setting the standard at the moment and that's why all the topteams are there. Ask anybody, teams, judges etc. they will all tell you the same.

Not to take anything away from anybody, I've seen RIT in action a couple of times and they're great competitors. And yes, if they become better engineers due to taking on a huge challenge of developing an aero package, that's a victory as well.

cheers,
MH

[Zac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bemo:
You really think that saving weight is the only reason for a monocoque? </div></BLOCKQUOTE>

No, I'm well aware that it is not.

[Bemo]

That was directed to J_poo. Looks like he isn't aware of that.

[Lorenzo Pessa]

About aero

First of all: the rules are not friendly. Having a minimum radius of 12.7 mm at LE and 3 mm at TE is really bad for wings!

Try to focus on what the car is going to do on the race.

Acceleration:
- doubling (or Cd will not affect too much on final timing (better to work on others sector)
- Cz is useless
- less weight is better

Skid Pad:
- Cd not important, I think you will have enought power from you engine to maintain constant velocity
- Cz can give some time improvement.

Endurance/autocross
- Cd could be considered (fuel comsumption)
- Cz could be considered, it depends a lot from the track layout. at FSG09 there weren't fast corners. at FATA09 there were some "fast" corner.
- weight is really important

Evaluate the difference of weight of a car with and without aero package.
Evaluate how much Cz you can generate from wings, underbody and heat-exchanger. Try to kill positive lift from tyres, nose and driver.

- don't forget when you need Cz, I mean when you are in a corner, the aerodynamics efficiency decrease
- don't forget you have to build your aero package: not well finished parts are not efficient.
- don't forget that wings are at the front and at the rear: you increase your steering inerzia.

Then take a simulator and try to understand at which Cz your lap time stars to decrease.
If you can reach it, you can install an aeropackage.

If your car is more than 250 kg (about 550 lb for the measure not yet civilized countries) don't think about aero, try to do it lighter!
And if you are less than 250 kg it would be easier and cheaper to work on other sectors.

Don't thrust anyone (me too!). Only lap time (and score) can say if you are right or wrong.

Don't forget to remember your drivers to avoid cones.

Lorenzo Pessa

[The Neck]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Enter our friend from RIT saying: my dear friend Jaehyun, don't forget RIT won Cali WITH an aero package.
Now maybe I'm a nutjob, but isn't that at least implying RIT won Cali because of the aero package? </div></BLOCKQUOTE>

No, again you're mistaken MH. Peterson didn't claim that we won because of aero; I know this because I talked to him the other day about it.
A direct quote from Jaehyun: <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why can't Aerocars Win the comppetition?? </div></BLOCKQUOTE>

He answered by saying RIT ran aero, and they won competition. There was no correlation made between the two from RIT's end.

[MH]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
No, again you're mistaken MH. Peterson didn't claim that we won because of aero; I know this because I talked to him the other day about it.
A direct quote from Jaehyun: <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why can't Aerocars Win the comppetition?? </div></BLOCKQUOTE>

He answered by saying RIT ran aero, and they won competition. There was no correlation made between the two from RIT's end. </div></BLOCKQUOTE>

Ah, I see. You're the type of guy that likes to rip sentences out of their context. Do you really have no clue of what our friend Jaehyun really meant with his question?

Strangely I was not aware of your conversation with Peterson. My bad.

It looks like Peterson answered the literal question, not the intended question. Problem solved.

[TPeterson]

MH

It seems as if you are more interested in arguing about how good of a team RIT is. I didn't intend to get the thread so off topic. Let's get back to the original question of the tread.

[Sooner_Electrical]

Our team has ran Aero for awhile and here are some of the main reasons I would argue for running an aero package:

You will have have a clear advantage if there are any significant high speed corners, which in FSAE competitions is always hit or miss but in SCCA courses (which theoretically our weekend autocross cars are supposed to be designed for) aero is a must, just look at nationals results for the last 10 years.

Aero makes the car easier to drive quickly, if you have inexperienced drivers aero will help cover up minor mistakes and make them more confident pushing the car to limit.

Pretty much all forms racing has some sort of cfd/aero requirements and are in need of qualified engineers to fill this increasingly important science.

I seem to remember one year where there was a semi high speed course for autocross in the FSAE East competition where UTA and OU running aero gaped the other 118 teams by 2.5 seconds, which is a huge point advantage going into endurance (which I believe neither finished). That being said there are some major disadvantages, the biggest ones already being mentioned: Cost, Man hours, Cooling concerns, aero guy getting pissed every time a cone is hit, carbon fiber splinters and all the sanding.

I truly believe that the reason there are not more winners with aero packages (although there are a significant number of top 10 finishes) has to do with numbers. If you have 100 teams and 25 of them have a significant chance of winning the competition and 2 of them are running aero there are a lot of factors and odds stacked up against them. Although aero packages are growing in popularity there are still a lot more very good teams with out aero going for the same spot we were/you are. I am confident that a car with a well designed aero package has an advantage over a car with out aero, and it is only a matter of time before all the competitions are won by teams with aero :-).

[MalcolmG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I am confident that a car with a well designed aero package has an advantage over a car with out aero, and it is only a matter of time before all the competitions are won by teams with aero :-). </div></BLOCKQUOTE>

Not unless there's a reasonable change in the venue/track layouts at FSAE-A.

[dazz]

Like the Monash team don't already have enough motivation to beat you Kiwi's! Way to throw down the challenge. Both teams are looking strong at this point in the lead up to comp, lets hope there aren't any major mechanicals and we get a good show. Too bad Deakin wont be in the mix.

[D Collins Jr]

Hey, without ripping on these competitions I'm going to mention for not being competitive, let me remind everyone that Sophia wins Japan on a regular basis. They run a rear wing. Virginia was contested between two aero cars this year. TU Graz won Michigan with a undertray, and so did RIT at California. I have only been to US events myself, but at all the events I have attended, there has been at least one aero friendly corner.

As far as cars at FSAE West running wings: there do seem to be a higher concentration of aero cars in the US. The teams that are building these cars are bulding them "for the weekend autocrosser." These teams also regularly win the SCCA Nationals. My understanding is that there is no similar competition overseas that would promote such aero cars. These cars are usually fast on track (to be clear, I am NOT saying that they are fast because of aero. I find that these are excellent teams before they implement aero, and then tackle a new challenge), have good manpower, and are well organized.

As far as winning the event, there's alot more to it than winning on track. We've all seen events come down to less than ten points, that can be made up in static events. Things can go wrong, other teams can be amazingly fast, etc. And aero teams don't always score well in design since some design judges don't believe the data (and yes, I'm thinking of you Mr. Fox).

Now to sit back and watch the flames fly again...

[Adambomb]

+1 to Sooner Electrical and D Collins Jr.

I can say that we're in the boat of wanting aero, but for us aero comes in line after having a car that has everything else sorted out (not to mention taking care of those aforementioned static event points http://fsae.com/groupee_common/emoticons/icon_wink.gif ) . Basically for the last 3 years we've had a full aero package in the developmental stages, but unless we magically gain a bunch of dedicated and competent manpower, the plan is 2011.

Now I'll say that from the looks of it, Michigan did not appear to be aero friendly. Autocross seemed silly tight, at most one turn where wings would have been worth their weight in downforce. Endurance didn't look much faster, although I only walked the course, didn't actually drive it or watch it...was too busy trying to get our starter to work. http://fsae.com/groupee_common/emoticons/icon_frown.gif But then again, that's just my opinion...I never drove the endurance course, I did autocross in the rain, and the whole damned week was such a blur for me it's hard to say with any certainty. California and Virginia looked considerably faster from the pics at least, and that's what I hear from others. As for overseas comps, I have no idea (that's a couple years down the road for us, economy willing).

As for SCCA autocrosses, I wish we had aero for every event we go to. We've been up to about 90 mph on some events, and average speed is closer to 50. When was the last time a non-aero car won nationals? Even though aero may be of debatable value at competition, for the teams that spend more time at autocrosses IMHO it's worth it. And hey, isn't it in the spirit of the rules that we're making weekend autocross cars?

As for justifying with test data, I would submit the possibility that with a bit of ingenuity one could get much more valid results with some very basic data aquisition (perhaps even without the fancy-pants DAQ equipment) and track time than any amount of CFD or wind tunnel data. Lap sims sure don't hurt either, and that's another one of things that takes more time than money to accomplish.

Just my $0.02.

[ZAMR]

http://www.facebook.com/photo.php?pid=30404765&id=1131420085

I love debating the engineering merits/demerits of aero packages, but they make the car look sweeeeeeet.

[ZAMR]

You may think looks aren't important, but when you're trying to recruit new members or find new sponsors looks ARE important. No one is going to pay attention to you if you look like a go-kart with no body and a radiator dangling off the side. Wings make these cars look more like indy cars which people can relate to.

Besides, the layup techniques you inevitably experiment with prove invaluable when it comes time to graduate and get an aerospace job. The drag from them is negligible (we have accel times that prove this). If you are motivated enough you can eliminate the weight of the wings ELSEWHERE in the car. We were under 400lbs at West with a full wing package (a heavy one at that).

WINGS: downside, it looks like a racecar

Zach Moorhead
Sooner Racing

[Bobby Doyle]

Zach, I have a lot of respect for you man, but I disagree with just about everything you just said. Lol http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[ZAMR]

You would. Suspension guy! http://fsae.com/groupee_common/emoticons/icon_razz.gif

I like aesthetics what can I say.

[J_poo]

I apologize for being such a "Negative Nancy" but I am intrigued as to the weight of cars with monocoques, what does the monocoque itself weigh and why is it worth your time to build one if the end product is heavy, I would assume that there is more work to be done on other areas of the car. As to your alluding to other benefits of a monocoque I would love to understand what the additional benefits are. Also I would like to now what you think an aero package weighs. I am trying to use this topic to increase my understanding of the total system and sometimes it is useful to play the devils advocate.


bye the way jab at the English Engineering units system is indeed well deserved I hate it in an engineering sense but I still visualize things in lbs, ft, and inches.

[ZAMR]

"A coque and two bores is all you need"

-Jayhawks Motorsports

and don't forget your wangs.

[RenM]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ZAMR:
If you are motivated enough you can eliminate the weight of the wings ELSEWHERE in the car. We were under 400lbs at West with a full wing package (a heavy one at that).
</div></BLOCKQUOTE>

As we dont have a minimum weight every extra weight is extra weight. So if you were under 400lbs you could have been under 380 without aero for example.

I didnt have a very close look at aero cars during autocross and endurance but how many cones do they usually pick up with their front wing?

[Crispy]

They give out track maps before tech at the events. So if there is a chance that aero is not worth it, there is no reason you can't make the call on site. It would be cool if a team had a good way of determining if an aero package was going to be worth it (in terms of points) for the whole event (endurance, autoX, fuel, etc) with the specific track maps. It would take a lot of testing/preparation/validation with and without aero, but you would end up knowing your car quite well. Kind of ridiculous I admit, but could be cool.

Some other advantages of a monocoque:
-Easier to deal with the templates
-More flexibility in terms of suspension placement
-Manufacturing (it may be simpler for some teams to cnc a mold and layup, than to build a jig and weld a chassis)
-You get to learn about composites

Our '09 car
Front Monocoque 13 kg with front hoop
Rear Steel frame 10 kg with main hoop

A lot of areas were significantly overbuilt, and a few were underbuilt (hence our failure/repair at LA). We have learned a lot since then. I think a "stiff" 30-35lbs (13.5-16kg) chassis with hoops would be quite difficult.

[Mike Cook]

First off, happy thanksgiving. I love the usa.

Second, our lap time simulator pretty much shows that a good aero car is better on every track, slow or fast. The weight of the vehicle is insignificant unless you are running aero because the tires are just not very load sensitive at our weights. Less weight only improves the car in a couple cases: 1) if you don't have enough power to spin the tires (over 30mph) 2) if you are undertired (we aren't) 3) you are running an aero car. The fastest car I have ever seen in skid pad is UMR and they aren't particularly light, but they do have aero.

[Bemo]

About the advantages of a monocoque I totally agree with Crispy. In my opinion these points are even more important than weight.

About aero. Lap time simulations are a nice toy, but reality often looks different. Have you also calculated the height of the cog. By putting a rear wing at the car it will definitely higher. And with a front wing you have to keep a bigger distance to the cones to avoid penalties (all aero cars I've seen in action so far had a lot of trouble about that).

In the end the major disatvantage in my opinion is the extra manpower you need. If it shall bring you any advantage at all there is a lot of work to do to design and manufacture it.
Every car at the competition (including ours of course) has quite a lot of problems where you can gain more performance with that effort.

Just my opinion.

[RenM]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mike Cook:
First off, happy thanksgiving. I love the usa.

Second, our lap time simulator pretty much shows that a good aero car is better on every track, slow or fast. The weight of the vehicle is insignificant unless you are running aero because the tires are just not very load sensitive at our weights. Less weight only improves the car in a couple cases: 1) if you don't have enough power to spin the tires (over 30mph) 2) if you are undertired (we aren't) 3) you are running an aero car. The fastest car I have ever seen in skid pad is UMR and they aren't particularly light, but they do have aero. </div></BLOCKQUOTE>

weight is the most important factor for fuel consumption and minimizing weight will help you in autocross and endurance as well. You can not compare the dynamic performance of a car in skid pad because your inertias dont play a role in steady-state skidpad testing.

[ZAMR]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RenM:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ZAMR:
If you are motivated enough you can eliminate the weight of the wings ELSEWHERE in the car. We were under 400lbs at West with a full wing package (a heavy one at that).
</div></BLOCKQUOTE>

As we dont have a minimum weight every extra weight is extra weight. So if you were under 400lbs you could have been under 380 without aero for example.

I didnt have a very close look at aero cars during autocross and endurance but how many cones do they usually pick up with their front wing? </div></BLOCKQUOTE>

Cones: I would guess as many as non-aero cars!

This is all about percentages in my mind; the beneficial downforce from wings increases as you weight decreases, so your incentive to run wings eventually overcomes your incentive to be lighter (However that decreased yaw acceleration will have a larger effect on a lighter car than a heavier one).

Here’s the question then: is a 400lb car with wings “faster” than a 380lb car without? And is a 500lb car with wings faster than a 480lb car without? And why?

I don’t know about the 480lb and 500lb cars but I do know they are both going to be really slow and wings are the least of your worries ?

Another interesting question: if there was a minimum weight rule, would you run wings? Just curious.

[Mike Cook]

Man... you guys are a tough crowd. It has been a long day, lots of drinking, lots of eating.

I'm hesitant to say these things because my team might lynch me, but:

Our lap time simulator looks at a lot of things:
Wheelbase
track
cg ht
LLTD
COF
DF
DF distrbitution
drag
power
fuel economy



Having a wide front track only hurt you in a few situations, I challenge you to draw it out in autocad(kink, 180 deg turn with cones on the outside). More freq than not its your rear tire that will hit the cone. Plus there really isn't that much advantage to having your front wing as wide as your front track because the outside of the wing is the most inefficient part. Really, having a wide front track just allows you to have wider rear wing which is the limiting factor (surprisingly) in your aero setup (if you do you front wing correctly, also depending on your weight distro). Driving with a wing definitely takes a little practice but if designed correctly, it will rarely force you to alter your path from the non-wing line.

Weight is an important factor when improving fuel economy. I don't think our team is ever gonna win fuel economy(with an f4i)...nor do I really care, fuel economy is for suckers. When you all graduate and get your jobs at GM or Ford you can focus on fuel economy but right now its nice just to race cars. No one gets excited at fuel economy...thats for sure. FSAE is basically a really fun thing that makes engineering school bearable...if you keep keep adding un fun things to it, for the sake of getting a better education, well, people are going to stop wanting to do it all together and then they get nothing from it at all (future truck comes to mind)

With that said, we were a 500+ pound car and we won accel multiple years, and won endurance (second place in skidpad). How do all of you light weighters argue this? If the tire fell off so badly with load this would surely be impossible. Honestly, I'm not here to gloat, but after reading these forums for long enough any sane person would believe that this is absolutely impossible. Our lap time simulator suggest that weight is a relatively insensitive parameter to lap time, but whats far more important is where you put the weight. Down force seems to always make the car better regardless of how much drag you add (but this of course hurts fuel economy). Im not a big believer of tire load sensitivity in fsae because if you are overloading a tire, you can always choose to go to a wider tire in which it won't be overloaded. Also, we have huge problems with getting any kinda heat in the tire, so as you add load temperature increases which leads to a higher COF. Of course the tire COF falls off a little with load, but these two effects probably balance out. I do know that most slicks seem to have an activation temperature in which the COF changes drastically which seems to be around 120ish for us. So if you aren't getting to those temperature, you got problems.


Anyways its getting late, but for fun, calculate how much 1000lb of DF at 60mph would kick ass?

God I miss Z and his brown gokart...

[Bemo]

Is anyone surprised that a lap time simulation tells you that you're gonna be faster with more downforce?
In theory there is no doubt about this, but to have a properly working aero your whole car has to behave different. I'm pretty sure that your car should roll much less than normal with aero for example.
So it is quite difficult to figure out how much performance you can get by aero. If you want to drive with an aero package or not is a fundamental concept desicion and will affect a lot of parts of your car.

And I wouldn't just say that fuel is for suckers. You can 100 points in fuel + you won't earn a lot of points in design with that attitude, so it has quite a big impact on your overall result.

[Hector]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">...fuel economy is for suckers. When you all graduate and get your jobs at GM or Ford you can focus on fuel economy but right now its nice just to race cars. No one gets excited at fuel economy...thats for sure. </div></BLOCKQUOTE>

If you think fuel economy isn't a part of almost any racing series, you're sadly mistaken. Lots of testing and analysis is done to determine the effects of fuel savings vs. lap times. In Indy and F1 they have the ability to lean out the mixture on the fly, and in NASCAR they begin short shifting or keep the car in top gear to save every drop. I watched Rolex series race last season where the 1st place car with a lead of several seconds literally ran out of gas down the final straight, and coasted to a 3rd place finish as he was passed just feet from the finish. Ask that team if they care about fuel economy. Even worse for the poor driver, is was to be his first win in 5 years in the series.

Anyways, as for the aero in FSAE argument, I'm still waiting to see a team win it all. You can argue that aero teams have earned that highest dynamic scores at events, but FSAE isn't about racing, it's about these 1000 points that you can earn, some of which come from racing. I've seen some fast aero cars in recent history, but I'm still waiting to see one pull out the big win at either Michigan or Germany.

/talking full aero, not just an undertray

[Mike Cook]

I'm pretty sure I never said fuel economy wasn't important. What I said was no one I have ever met as a student or in Nascar, or in the military has ever been thrilled or excited about doing anything with fuel economy.

[Lorenzo Pessa]

Who don't believe in fuel economy had never seen Rennteam Stuttgart fuel tank and never seen the smile of the gas man when you go to get the fuel for testing.

About sim: do you use a software or a hardware (real) driver?

About weight: a lighter car need less manpower to get on and off the truck.FSG 09 p1 (http://www.youtube.com/watch?v=h4WKZc-yKeU&feature=PlayList&p=6183CBE578F0A720&playnext=1&playnext_from=PL&index=40) (start from 3:30)

See you,
Lorenzo

[ttk3]

An aero package is a double-edged sword. When engineered AND executed well, it certainly has an undeniably positive effect on the overall performance of the vehicle as a whole, given the correct circuit layout. I won't divulge any metrics, but the RIT package was well worth its meager weight, even in skidpad.

At the same time, drivers must learn to adjust their technique to take full advantage of available lift. The package adds weight, moves the CG in every direction statically and dynamically. On top of that, the car now has a wing/tray obstructing maintenance, set-up and those intense emergency repairs (on the autoX start line with 10mins to close...) of engines, suspension, pedals, etc. Any typical seepage from engine and drivetrain will be in plain view for an endurance judge to view, either puddling neatly on a tray or splashed under a wing.

Aero alone is not the reason a car will get to the top of fsae. A team with a simple, reliable design, dedicated members, strong leadership and lots of seat-time will give any big-budget, aero team with fancy steering wheels a run for their money.

[D.J.]

aero looks badass

[Wesley]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RenM:
weight is the most important factor for fuel consumption and minimizing weight will help you in autocross and endurance as well. You can not compare the dynamic performance of a car in skid pad because your inertias dont play a role in steady-state skidpad testing. </div></BLOCKQUOTE>

What now? Since when has vehicle weight really had anything to do with fuel consumption? In a passenger car, absolutely, but at WOT, the engine doesn't care if you weigh 1000lbs or 100lbs, it still burns the same amount of fuel. And you don't accelerate for longer, either, because you're operating in a fixed distance.
It will make some small effect, but the MOST important factor? By no means whatsoever.

And Zach, if you'll remember, we did get 3rd at Cali with a 490 lb car. It was not a slow car.

[RenM]

Why do you think a single cylinder car needs a lot less fuel then a 4 cylinder car? Its not because the single cylinder is a lot more efficient it comes down to weight.
The equasion of kinetic energy is very simple:
W=1/2*m*v^2

So if you have two cars on the track which drive at the same speed the car that is lighter will need less fuel, because it needed less energy to reach the speed.

Of course you can always spoil your fuel efficiency with a bad engine mapping, but if you have done your job right it will go down to weight.

[Scott Wordley]

First time i check the forums i think this year and couldnt resist. A lot of points i wanted to comment on so have cut and pasted quotes.

If anyone wants to talk aero seriously with me send me an email.

Anyway... run wings or don't. Its your choice.

Just like a single-cylinder, a turbo, a monocoque or whatever fancy add on you can thing of, they will not win you a competition. Only solid cars and teams with few weaknesses and a lot of luck win competitions.

This is a rant i've made several times before on this forum so rather than add further conjecture, a few comments on previous posts based on our 8 years experience with wings:

"There's not enough wind at the competition" - MH

Sometimes there is too much. We nearly went over in 2004 when caught in a big side gust while cornering. Couldnt find the pic to post, but something to consider.

"Of course, what you have to decide is whether or not that improvement in lap time is worth the other performance trade-offs (increased fuel consumption for example) and use of resources."

Increase in fuel consumption is minimal, we would guess from measurements around 100-200ml. Teams without wings, what is the variation in your fuel useage with different drivers? You'd be surprised.

"Aero packages on FSAE cars take 2 things that every other system requires: time and manpower" - Pennyman

Perhaps, but so do turbos, monocoques, pnuematic shifters and anything else trick. Smart teams will target their resources where they see the most potential benefits. I can tell you wings are a lot easier to design and manufacture than a monocoque and we see plenty of teams with them. How much time (or points to be specific) does a monocoque gain you in comp? Why does that not need to be justified?

"weight, weight, weight..." - everyone

Forget your equations for a second and determine how important weight REALLY is. Experimentally. Its very easy to add weight to your car. See if you can MEASURE the difference in performance in your car with an additional 10kg. In any event. I dare you.

"Acceleration:
- doubling (or Cd will not affect too much on final timing (better to work on others sector)
- Cz is useless"

A decent, adjustable, wing design will add negligible drag in acceleration event. You just have to be smart about it.

"don't forget when you need Cz, I mean when you are in a corner, the aerodynamics efficiency decrease"

Wrong, at least in our case. We have designed our wing to produce more downforce WHEN YAWED, than in a straight line.

"don't forget that wings are at the front and at the rear: you increase your steering inerzia"

True. But this increase in yaw inertia(?) is more than offset by the increased cornering potential. Our cross-over speed is about 25 kmh. This is about our minimum track speed.

"Aero makes the car easier to drive quickly, if you have inexperienced drivers aero will help cover up minor mistakes and make them more confident pushing the car to limit." - sooner

Yes.

"I truly believe that the reason there are not more winners with aero packages (although there are a significant number of top 10 finishes) has to do with numbers. If you have 100 teams and 25 of them have a significant chance of winning the competition and 2 of them are running aero there are a lot of factors and odds stacked up against them. Although aero packages are growing in popularity there are still a lot more very good teams with out aero going for the same spot we were/you are. I am confident that a car with a well designed aero package has an advantage over a car with out aero, and it is only a matter of time before all the competitions are won by teams with aero :-)"

Agreed. If Stuttgart, UWA or RMIT ever decide to use serious aero we are all screwed. Also Stuttgart have the best full scale rolling road wind tunnel in the world. We nearly got our car in there in 2006 but it was going to take too long to change their belts. Enjoy this golden period in FSAE, before you NEED wings hehe

"Not unless there's a reasonable change in the venue/track layouts at FSAE-A" - Malcom

I disagree. If we get a track that is to the rules we are more than happy. If we get a track that is tighter like last years 5.5-6m slaloms and parts of the track are less than 2.5 m wide then you have to do other things to get through there fast. Using a 1.0m track like you guys did is one option... but there are others.

"some design judges don't believe the data (and yes, I'm thinking of you Mr. Fox)." D Collins Jr

If they dont believe the data you need to show them on track, as with anything.

"with a bit of ingenuity one could get much more valid results with some very basic data aquisition" Adambomb

Very True. I hear you can get strain gauged rod-ends on ebay these days for $80?

"but how many cones do they usually pick up with their front wing" - RenM

Wings dont hit cones, drivers hit cones. Oldy but a goodie.

"So if there is a chance that aero is not worth it, there is no reason you can't make the call on site." - Crispy

Very true. We are always prepared to pull the wings at short notice and have done so at very fast, straight hillclimbs in the past.

"Second, our lap time simulator pretty much shows that a good aero car is better on every track, slow or fast. The weight of the vehicle is insignificant unless you are running aero because the tires are just not very load sensitive at our weights. Less weight only improves the car in a couple cases: 1) if you don't have enough power to spin the tires (over 30mph) 2) if you are undertired (we aren't) 3) you are running an aero car." - Mike Cook

Its not insignificant but i broadly agree with the sentiment. Identify whether you are power limited or grip limited. How? Look at your endurance logged data. Spending less than 20% of the tie at WOT? Your grip limited. Spending more than 30% of the time at WOT? Your power limited. Add whichever you lack. Simple.

"Have you also calculated the height of the cog?" - Bemo

If you do not MEASURE the CoG and inertias of every car that you build then you are not serious (im sure stuttgart ARE serious!). If you add wings you should know what their effect is on these parameters and if the down force is worth it. In our case it is.

"the beneficial downforce from wings increases as you weight decreases" - Zamar

Very true. Our wings would work much better on a light weight single car. Your grip is a function of the downforce / weight ratio, the higher the better.

"Really, having a wide front track just allows you to have wider rear wing which is the limiting factor (surprisingly) in your aero setup" - Mike Cook

Really? We have always been limitted by our front. Without going to a bi-plane (we tested one!) its hard to generate enough front, considering we can make the rear as big (chordwise) as we needed.

"Im not a big believer of tire load sensitivity in fsae because if you are overloading a tire, you can always choose to go to a wider tire in which it won't be overloaded" - Mike

Exactly. How is it that everyone has got their panties in a knot about load sensitivity of tyres, on FSAE cars! Please think about the applications these tyre are usually used in, invariably they will see MUCH higher loads than on a 500+ pound FSAE car, even with serious wings. And remember even if the efficiency of the tyre is decreasing (slightly from our data) its still additional grip that you never had before. Its about EFFECTIVENESS not efficiency here.

Take one corner say 300 pounds

300 x 1.7 (CoF) will always be less than

300 x 1.7 + 30 x 1.4

for whatever reduced CoF you choose. You cannot add reaction force and get less grip. Look at your data (I wouldnt trust TTC but thats another rant) and do the numbers.

"but for fun, calculate how much 1000lb of DF at 60mph would kick ass?"

How much fun would 1000 KG of downforce be at 160 km/h? We should be able to tell you by mid next year...

"God I miss Z and his brown gokart..." - Mike

Me too. But glad there are still a few sensible people like yourself to keep everyone here honest!

"And I wouldn't just say that fuel is for suckers." - Bemo

Well said. Fuel is where the really good teams show their class. More than anything fuel will dictate what the future of this competition looks like (ie single vs 4). Which is a shame i think, the balance was good where it was.

Thats it for now,

Scott
Monash University
2000-2009
"oh... and the wings dont work"

[Bemo]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:
"Have you also calculated the height of the cog?" - Bemo

If you do not MEASURE the CoG and inertias of every car that you build then you are not serious (im sure stuttgart ARE serious!). If you add wings you should know what their effect is on these parameters and if the down force is worth it. In our case it is.
</div></BLOCKQUOTE>

That was a bit ripped out of its context. It was ment as a reply to the lap time simulation someone mentioned. The point about these simulations often is that it isn't a big surprise they tell you that you would be faster with more downforce while leaving all the other parameter where they are.
These simulations can only give you any serious results if you also care about the drawbacks of a wing package.

And you're right, the driver affects fuel a lot. But a heavier car needs more fuel for the same lap time if you don't change the driver. So this is a drawback of an aero package which is at least worth to mention.

[RenM]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:
"Aero makes the car easier to drive quickly, if you have inexperienced drivers aero will help cover up minor mistakes and make them more confident pushing the car to limit." - sooner

Yes.

</div></BLOCKQUOTE>

Why should it be easier to drive an aero car? Cars with heavy aero are rather harder to drive because you have to push beyond the limit to make the aero work right and with FSAE cars that produce only little downforce i do not think that there is any difference from driving without wings. I have not driven an fsae car with wings yet so i can not really tell, so please correct me if i am wrong.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:
"Not unless there's a reasonable change in the venue/track layouts at FSAE-A" - Malcom

I disagree. If we get a track that is to the rules we are more than happy. If we get a track that is tighter like last years 5.5-6m slaloms and parts of the track are less than 2.5 m wide then you have to do other things to get through there fast. Using a 1.0m track like you guys did is one option... but there are others.
</div></BLOCKQUOTE>

Even if a track complies with the rules it can be a rather slow and tight track like in Germany.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:
"but how many cones do they usually pick up with their front wing" - RenM

Wings dont hit cones, drivers hit cones. Oldy but a goodie.
</div></BLOCKQUOTE>
Thats like blaming the driver for picking up cones with a car that has a ridiculous wide track for example.
What i wanted to say is that you might have to choose a worse line because of your wings.


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:
Well said. Fuel is where the really good teams show their class. More than anything fuel will dictate what the future of this competition looks like (ie single vs 4). Which is a shame i think, the balance was good where it was.
</div></BLOCKQUOTE>

With the revised fuel rule for 2010, things are back to normal.

[Pete Marsh]

[/QUOTE]

Why should it be easier to drive an aero car? Cars with heavy aero are rather harder to drive because you have to push beyond the limit to make the aero work right and with FSAE cars that produce only little downforce i do not think that there is any difference from driving without wings. I have not driven an fsae car with wings yet so i can not really tell, so please correct me if i am wrong.

I was lucky enough to get a drive of the Monash car earlier this week, and yes it is easy to drive and see a definate advantage from the wings. I didn't find the limits of the car, however there is no doubt in my mind that at the level of risk/effort I drove at, it is much faster than any similar power to weight FSAE car I have driven before.

It seems to me any of the trick systems will give you something when well deleloped. Wings, turbo, Kinetics, ultra light etc. The issue is the dilution of reasorces and the rest of the car. Can you make a balanced package?

Now if we could just get Scott to move to WA(and bring the wind tunnel), and who ever made the Gongs turbo thing go like that, and Malcom to come and make it all happen on time, and a driver that spends a little less time going backwards, then we could give the Germans something to worry about.

Pete

[MalcolmG]

Last Sunday I remembered what I'd written in this thread about wings not winning FSAE-A and wondered how long it would be before someone picked me up on it http://fsae.com/groupee_common/emoticons/icon_smile.gif

I think the tough thing about FSAE-A is that depending on how the organisers are feeling, it could easily go back and fourth between favouring certain vehicle characteristics - or not necessarily favouring but at least being more or less suited to things such as wings, 4s, singles, etc.

I can't wait to see how things pan out for Monash next year, if you guys make the changes that you have in the pipeline it'll undoubtedly be a tough year, but it'll be interesting to see how a lightweight car with wings performs - seems like it could be quite a ridiculous beast if you pull it off. In fact, maybe I should talk our guys in to mounting our '06 wings to the '09 to see how it goes http://fsae.com/groupee_common/emoticons/icon_smile.gif

[ben]

With regard to track layouts; Personally I'd like to see the autocross and endurance courses determined at least 18 months before comp, fully digitised to indicate width and elevation change.

If this was done we'd have a genuine design competition like Aero Design. Without this there are clearly courses where aero's beneficial but you have no way of knowing prior to rocking up at the event.

Mind you F1 might be fun if they didn't know the track layout before a race weekend :-)

Ben

[Mike Cook]

I agree completely Ben. I also think this would take a little bit of the driver element out of the course because you could lay it out and practice it before hand.