New Aero Packages for 2011 Rules

[Scott Wordley]

Hi everyone,

Like most of the current aero teams we were extremely happy with the recent rule change which will allow even bigger wings and diffusers in 2011.

Our team started design and CFD work as soon as we heard the news, and are pretty close to finalising our wing and diffuser designs and starting to build them for the Aussie comp in December.

Anyway, I started this thread for a couple of reasons:

1: Firstly, it would be great to see pics (finished parts, cars or CAD, CFD) from any US and European teams who have designed new wings or diffusers to these rules. I saw the pics from Auburn and noticed they are running massive tunnel diffusers this year, neat.

2: We are having difficulty integrating the jacking bar with the diffuser, without giving up that 300mm center section. We are interested in seeing how other teams are trying to get around this limitation. We have a few ideas...

3: I am very interested to know how teams running aero designed their packages (2D or 3D CFD, isolation or full car), and what ideas they have to validate them (wind tunnel, flow vis, pressure tapping, lap time etc).

4: What levels of downforce and drag do you think you will make on track, lets say at 60 km/h (37 mph), which is a reasonable average speed?

5: I am also interested to hear how teams justify running aero on their cars. This may be as simple as it makes the car faster or easier to drive, we like the way wings look, or we do a full competition point sensitivity and team resources analysis.

6: If your team does not run an aero package have the new rules forced you to re-evaluate this decision? I'm interested to hear from any teams whose analysis still shows that wings and diffusers are still detrimental to the car's performance even with the bigger package space.

And one last conversation starter...

7: Can wings be used effectively on a 50 hp, 160 kg single cylinder car? If so, would the performance increase be less than or greater than that seen on an 80 hp, 210 kg 4 cylinder car?

Discuss!


Regards,

Scott Wordley

Monash Motorsport
http://www.monashmotorsport.com/

[Scott Wordley]

To give you an idea of what we are thinking, at least for the front wing here are some photos from a test we did recently.

We wanted to find out how big the front wing could be before obscured the vision for a short driver (like Luke!). We also wanted to check if the extra forward length made any difference to the driving line, and if we would simply hit a lot of cones with that outside corner. The results were pretty interesting...

Try again:

<a href="http://www.flickr.com/photos/60123418@N03/5491051272/" title="high speed cone collecting by Scott_Wordley, on Flickr"><img src="http://farm6.static.flickr.com/5296/5491051272_6910e54dbb.jpg" width="500" height="375" alt="high speed cone collecting" /></a>

<a href="http://www.flickr.com/photos/60123418@N03/5491051272/" title="high speed cone collecting by Scott_Wordley, on Flickr"><img src="http://farm6.static.flickr.com/5296/5491051272_6910e54dbb.jpg" width="500" height="375" alt="high speed cone collecting" /></a>

<a href="http://www.flickr.com/photos/60123418@N03/5491053638/" title="2010 front wing by Scott_Wordley, on Flickr"><img src="http://farm6.static.flickr.com/5174/5491053638_2f619fff53.jpg" width="500" height="281" alt="2010 front wing" /></a>

<a href="http://www.flickr.com/photos/60123418@N03/5491052474/" title="mocked up bigger wings by Scott_Wordley, on Flickr"><img src="http://farm6.static.flickr.com/5294/5491052474_0435628198.jpg" width="500" height="281" alt="mocked up bigger wings" /></a>

[sbrenaman]

Originally posted by Scott Wordley:
5: I am also interested to hear how teams justify running aero on their cars. This may be as simple as it makes the car faster or easier to drive, we like the way wings look, or we do a full competition point sensitivity and team resources analysis.


The only way to properly justify running aero (and anything else, really) on a car is a laptime sim that takes into consideration the change in NSM weight distribution F/R as a function of speed. Then, do this for accel, skidpad, autox, endurance, and fuel economy, and figure out what gets you the most points.

Not the droids you were looking for? http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Scott Wordley]

Yep, that is one way to do it.

It can be done in excel with a week or so of hard work and careful checking. Geoff Pearson has talked about it extensively and we have listened carefully to all his advice and built in added functionality.

The new data table function is particularly good for assessing a matrix of possible changes (in this instance CD and CL) and generating points differences. An example of this is shown below (I obviously haven't left in the axis titles, or the increments so it could be anything... or nothing!).

http://img845.imageshack.us/img845/2264/example2variablesensiti.jpg

Is this how you guys are justifying everything on your car? Your website states you will be running tunnels and a diffuser this year so interested to hear what went into that design process.

Oh, and feel free to take those droids, they are not the ones I was looking for http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Lorenzo Pessa]

Originally posted by sbrenaman:
The only way to properly justify running aero (and anything else, really) on a car is a laptime sim that takes into consideration the change in NSM weight distribution F/R as a function of speed. Then, do this for accel, skidpad, autox, endurance, and fuel economy, and figure out what gets you the most points.

Not the droids you were looking for? http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

At least you need to account also the cost event.

[Scott Wordley]

Lorenzo, I disagree.
In our experience the actual (perceived?) cost of the car does not correlate strongly with the points a team scores for that portion of the cost event. Have a look over the results from any competition and you will see this is the case.

In terms of a competition point sim we find it is easiest to assume every car scores full points for all static events. That way you get an indication of the maximum point scoring potential of the car.

That's a subject for a whole different topic though, i will start it tomorrow. Let's talk aero here.

[sbrenaman]

Originally posted by Scott Wordley:
Is this how you guys are justifying everything on your car? Your website states you will be running tunnels and a diffuser this year so interested to hear what went into that design process.

A full lapsim was the plan but myself and the other member that were working on it aren't working on it currently. We're a pretty new team and a lapsim was ambitious.

However we should have some time to work on it before comp. We're also working on another fun project http://fsae.com/groupee_common/emoticons/icon_wink.gif If it works, we'll post info on what we did without enough time for people to copy. http://fsae.com/groupee_common/emoticons/icon_razz.gif

[DStevens]

Our team now has a project group looking at the change in aero rules, and I was wondering pretty much the same things you were Scott.

I would be interested in how the Aurburn team analysed their tunnels, and how effective they are.

I'm also interested in how people have progressed their design from initial concept, ie 2D isolated models, 3D isolated, 3D full car etc.

We are still tossing up whether we use ANSYS/CFX or Open Foam, and it would be good to hear how other teams go with either of these packages.

But I'm very interested to see the concepts that will come out at the comps through the year, I'm expecting a lot of BIG diffusers.

[Thrainer]

You could make a rotating jacking bar and the Magnus effect will give you a vertical force.

You can't really expect in-depth answers from other teams if you don't start off with giving your own information.

[Xeilos]

[QUOTE]Originally posted by DStevens:
We are still tossing up whether we use ANSYS/CFX or Open Foam, and it would be good to hear how other teams go with either of these packages.
QUOTE]

I will refer you to my post here:

http://fsae.com/eve/forums/a/t...=146104174#146104174 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/197106074?r=146104174#146104174)

I even had to do use the search function using my name as it was not coming up despite me knowing I posted something here on this topic.

I would avoid OpenFOAM. You will have nothing but headaches and a general loss/graying of hair. You should not be doing anything in FSAE that requires custom models programmed in C++ so save yourselves the headaches and go with a commercial package.

That is unless you/your school cannot afford a commercial package, then OpenFOAM might be looking attractive. I would instead refer you to CFDesign, who offer this package free to FSAE students. Whatever you do, do not try to use SolidWorks CFD (CosmoWorks or whatever it is called these day).

[RANeff]

Originally posted by Scott Wordley:
To give you an idea of what we are thinking, at least for the front wing here are some photos from a test we did recently.

We wanted to find out how big the front wing could be before obscured the vision for a short driver (like Luke!). We also wanted to check if the extra forward length made any difference to the driving line, and if we would simply hit a lot of cones with that outside corner. The results were pretty interesting...

http://flic.kr/p/9ne5Aw

http://flic.kr/p/9ne5WA

http://flic.kr/p/9ne5eN

http://flic.kr/p/9ne54A

Im not seeing any pictures?

[Scott Wordley]

DStevens:

We are currently using ANSYS CFX and like it a lot. We also have access to Star CCM+ and are looking into it. I know a lot of US aero teams use it.

RANeff:

Sorry will try again to get them working properly.


Thrainer;

Please see below, that should qualify.
Also rotating cylinders is not such a crazy idea... we have looked at it.


Aerodynamics for Formula SAE: Initial Design and Performance Prediction

Date Published: 2006-04-03
Paper Number: 2006-01-0806
DOI: 10.4271/2006-01-0806

Author(s):

Scott Wordley - Monash Univ.
Jeff Saunders - Monash Univ.

Abstract

The initial design of an aerodynamics package for a Formula SAE car is described. A review of Formula SAE rules relating to aerodynamics is used to develop realistic parameters for the specification of front and rear inverted airfoils, or ‘wings’. This wing package is designed to produce maximum downforce within the stated acceptable limits of increased drag and reduced top speed. The net effect of these wings on a Formula SAE car's performance in the Dynamic Events is then predicted. A companion paper [ 1 ] describes in detail, the CFD, wind tunnel and on-track testing and development of this aerodynamics package.



Aerodynamics for Formula SAE: A Numerical, Wind Tunnel and On-Track Study

Date Published: 2006-04-03
Paper Number: 2006-01-0808
DOI: 10.4271/2006-01-0808

Author(s):

Scott Wordley - Monash Univ.
Jeff Saunders - Monash Univ.

Abstract

The detail design and development of a high downforce aerodynamics package for a Formula SAE car is described. Numerical methods are first used to develop multi-element wing profiles which conform to FSAE rules while still generating high negative lift coefficients. A range of full scale wind tunnel testing data is presented for these designs, demonstrating their performance, both in isolation (free-stream), and on the car. Three different techniques are also developed for measuring the performance of a front wing in ground effect.


Aerodynamics for Formula SAE: On-Track Performance Evaluation

Date Published: 2007-04-16
Paper Number: 2007-01-0897
DOI: 10.4271/2007-01-0897

Author(s):

Scott Wordley - Monash Univ.
Jessie Pettigrew - Monash Univ.
Jeff Saunders - Monash Univ.

Abstract

The measured on-track performance of a Formula SAE car with a high downforce aerodynamics package is presented. Data logged from variety of different driving tests is used to determine how the addition of ‘wings’ affects the car's acceleration, cornering, braking and slaloming abilities. These results are then compared with analytical predictions for the same car, presented in earlier papers [ 1 , 2 ].

[Kevin Hayward]

Scott,

The new rules for aero are certainly very interesting. Even with the old rules, high levels of aero appeared to offer points according to the lap time simulations I had developed. However the difficult questions were the effect of potentially more cones hit due to the increased plan view of the car, the required resources to make an effective aero package work, and the potential reduction of mechanical grip due to weight of aero on unsprung or stiffer springs/dampers if sprung. Some of this is diffcult to assess without actually building a set and going running.

Any team not re-evaluating their concepts to the new rules is making a bad move, it is a major change to the aerodynamic potential of these vehicles. However this would be true of any major rule change such as the shift from 50 to 100 points for fuel economy.

The more worrying trend to me is seeing the development potential in the aero packages of the teams that are running them. It is as if Carroll Smith's predictions of 10 years ago are beginning to come true. I am sure that Monash are aware of many improvements that they could make to their car to improve mechanical grip and base chassis performance. This is despite the speed they have shown in all dynamic events. I am kept up worrying some nights of the team that will match UWA/Stuttgart style mechanical grip with a Monash aero package. (Please do not interpret this as insulting the quality of car that Monash make to carry the wings, it is not. Even without wings they would place very well)


Thrainer,

As Scott has posted, he has shared quite a lot of information with other teams on the topic of aero, including papers and quite a lot of posts on these forums. Monash have also shared sets of wings with other teams to do testing with them.

Kev

[vdubinthehouse]

Originally posted by DStevens:

I would be interested in how the Aurburn team analysed their tunnels, and how effective they are.



http://a3.sphotos.ak.fbcdn.net/hphotos-ak-snc6/197861_207365275944015_176332719047271_900993_6707 931_n.jpg

Aurburn Response:
Man I tell you what I stuck a diffuser in the bed of my buddy's pickup truck and drove it down the interstate bout 100 milnhour it didn't fly away so figgered it was pretty good

Good 'ol Boys
WAR DAMN EAGLE MOTORSPORTS
eeeerrrdienamics

Auburn Response:
I did 3D CFD iterations using Ansys CFX -> http://www.youtube.com/watch?v=HWK0IDqtGFM

As to how effective they are, We will be looking to validate these results this week or the next through real world testing. I'm still skeptical about accuracy the predicted values from Ansys.

I'm very eager to see how other teams have use the new regs, and I posted the above video hoping to get some feedback. This is our first year doing aero so I'm trying to learn as much as possible. Thanks.

[Superfast Matt McCoy]

Wings also make the car noticeably easier to drive, though it's hard to isolate that aspect and measure its affect.

Also, I had a conversation with a rules committee member about the new aero rules, and he thought it was odd that a lot of teams were expanding their aero packages to the maximum without being able to justify it. don't assume that the maximum of the rules is the best place to be. I saw a lot of rear wings in previous comps where i was skeptical that the overall system was balanced. I'm sure that will be an issue for some teams with the new rules.

[Lorenzo Pessa]

Originally posted by Scott Wordley:
Lorenzo, I disagree.
In our experience the actual (perceived?) cost of the car does not correlate strongly with the points a team scores for that portion of the cost event. Have a look over the results from any competition and you will see this is the case.

In terms of a competition point sim we find it is easiest to assume every car scores full points for all static events. That way you get an indication of the maximum point scoring potential of the car.

That's a subject for a whole different topic though, i will start it tomorrow. Let's talk aero here.

I was waiting the new topic, I beg your pardon if I reply here.

The 100 cost points are partitioned between cost of the car (40 pts), accuracy&...&visual inspection (40 pts), real case (20 pts).

Aero package influences directly only the cost of the car.
Taking data from the last FSAE-Italy I add the cost of aero packages to the cost of my team car (ET3).

I have done a rough estimate of the costs (conservative! so the resulting costs are less than real, I hope).

wings: 1600$
undertray: 900$

[Is someone laughing now? :-) ]

the cost of the car points are
ET3 : 16.064 pts
ET3+wings: 12.112 pts
ET3+underbody: 13.739 pts
ET3+wings+undertray: 10.187 pts

There is a difference from 4 to 6 points.

Aero doesn't affect other static events.

[Matthew Bell]

Lorenzo,
Remember that the total points score is 1000 points. So the cost difference makes up roughly 0.5% of a team's score.

That being said, I'm not 100% with Scott on this one either. I see the point of "eliminating" the static events from the event simulation when you're trying to decide "do we do wings or not?". But I think you have to keep in mind that you better be prepared for the static events when you get there - it's a lot easier to lose points in design than gain them because you overestimated your skills and resources.

This is all part of the game though, and topics like this could probably dominate the forum if we all stated our opinions.


To return back to Scott's original post, I too am very eager to see what the rules produce for winged wonders this year. Aero was a hobby of mine (I'm a Mechanical Engineer) and our team never had enough people working together to justify trying an aero package. I've moved on from University, and I intend to keep up-to-date with the FSAE community.

So: Pics or it doesn't exist.

[sbrenaman]

Originally posted by Superfast Matt
(rules committee member)... thought it was odd that a lot of teams were expanding their aero packages to the maximum without being able to justify it.

Could you make a lighter wing, mounted lower, further back in the car, with a higher l/d ratio? You would get the same Cp with lower weight, lower drag, and lower CG location.

I don't know enough about aero to answer that question.

[Luke Phersson]

sbrenaman,
Generally speaking, the lower the rear wing the worse it operates (Lower downforce and lower drag, but at a lower L/D), however if you run an undertray you could get a boost from the rear wing pumping the diffuser. The front wing and body work suck a lot of the energy out of the nearby flow, so getting the rear wing out've there can increase your downforce quite a bit.

One of the studies we did a could of years ago showed up to 50% loss of downforce (relative to freestream) at some of the lower heights we tested in the Wind Tunnel. There is some graphs in Scott's 2nd SAE paper on FSAE Aerodynamics.

The compromise you need to make is the total downforce level/drag moment arm(due to RW height)/and CG height. CG height only really becomes an issue with passing tilt/rolling on track due to side gusts than any load sensitivity effects.

[Scott Wordley]

Scott,

You could do that.

We have found FSAE rear wings to be particularly sensitive to height, and less so to for/aft location.

So you could go smaller, or less aggressive, lighter and higher and generate a similar downforce and potentially less drag. However your contribution to CG Height generally gets bigger, and your rear balance increases due to the higher drag component having a greater lever arm which needs to be reacted by more front wing (generally your limiting factor).

The more important question is: Are you sure you want the same levels of downforce, just more efficiently?

I doubt that most aero teams were content with the old package space, and so will be more than happy to exploit the extra available in the 2011 rules. Whether this will be enough to satisfy them remains to be seen...

My gut feeling is that the high powered 4 cylinder cars will fill every last inch with high lift multi-element wings and diffusers, much like the current state of affairs.

It will be interesting to see how the singles and twins respond, I think they will use the full space but need some degree of restraint to keep drag manageable.

[jerry_tung]

7.
UTA 2010 Car weighs 187kg 250cc T, best lap time in endurance in Michigan. 41.999sec if I remember correctly. 160kg car can be faster?

[Sly]

Matt, you left too soon. Were doing an aero package this year! First time for everything.

[bob.paasch]

Originally posted by Scott Wordley:

And one last conversation starter...

7: Can wings be used effectively on a 50 hp, 160 kg single cylinder car? If so, would the performance increase be less than or greater than that seen on an 80 hp, 210 kg 4 cylinder car?

Discuss!

Regards,
Scott Wordley
Monash Motorsport


I think this question has now been answered. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Bemo]

I'd say the question is, did you win all the points you lost in fuel, cost and accel back?

[AxelRipper]

Originally posted by Bemo:
I'd say the question is, did you win all the points you lost in fuel, cost and accel back?

Well with a second in fuel economy with aero, I'd say GFR did decent enough when they finished endurance.

[Chris B]

hey guys, UQ's not looking at running wings this year due to resource issues. that doesn't mean that we havent looked at it. we just decided that with the resources we have bigger gains lie elsewhere and are easier to tap into.

with regards to those that are increasing the size of wings, and this also ties into a post scott (from monash) made in another thread, if the points attributed to fuel economy have increased and you're adding even more surface area to the car, what things have teams looked at to regain some of the lost efficiency?

[Scott Wordley]

It sure has Bob, emphatically!

Axle ripper makes a good point, that should not be missed, GFR also managed to score like 93 points points out of 100 in Efficiency (which is slightly different to Fuel Economy).

But even judged on a pure Fuel Economy basis, they were still half a liter ahead of the fast 4s, so the gap would have been similar. Here in Aus we are staring down the barrel of 125 points for fuel this year, which is even more to the advantage of a thrifty single.

Was that Sam Collins from Race Car Engineering mag commentating during the final four cars at Formula Student Germany? Pretty funny if it was, having gone from this opinion:

http://www.racecar-engineering...gs/wings-and-things/ (http://www.racecar-engineering.com/blogs/wings-and-things/)

To... in reference to GFR's performance...

"this is extremely harsh on all the other non-aero design teams"

http://www.youtube.com/watch?v=QFZyzhPkqyw
at 2:30 sec. I guess the question of aero cars and fuel usage has been pretty well answered now as well.

We are still concerned with drag, particularly since we will be running a single with massive wings. Like Oklahoma have already shown this is a good way to deal with the drag problem... our new full car DRS:

http://www.facebook.com/video/...?v=10150397932483032 (http://www.facebook.com/video/video.php?v=10150397932483032)

[ben]

Originally posted by Scott Wordley:

Was that Sam Collins from Race Car Engineering mag commentating during the final four cars at Formula Student Germany? Pretty funny if it was, having gone from this opinion:

http://www.racecar-engineering...gs/wings-and-things/ (http://www.racecar-engineering.com/blogs/wings-and-things/)

To... in reference to GFR's performance...

"this is extremely harsh on all the other non-aero design teams"


Opinion pieces on engineering with no data to support them are basically the most pointless form of journalism - not surprised he backtracked when confronted by a nice shiny car with wings winning.

As has always been the case a wing car can do well provided it's engineered well, but a well engineered non-wing car can still do well also - that's the beauty of the regs.

What people also forget when writing for technical magazines is that it's not a pure racing event - the academic exercise of doing wings (particularly if you have facilities like Monash) is entirely within the spirit of the competition.

Ben

[bob.paasch]

Originally posted by Bemo:
I'd say the question is, did you win all the points you lost in fuel, cost and accel back?

We think so. Unfortunately, the FSG organizers wouldn't let us run all the dynamic events a second time without the aero. http://fsae.com/groupee_common/emoticons/icon_smile.gif Without that, there's no definitive data to prove the aero made more points.

I will say the 2011 FSG event was probably the least aero friendly event we ran all year. The wet skidpad lowered speeds to the point where the aero was way less effective than it was in California. The FSG autocross and endurance courses have a lot of 30 kph corners, a tight slalom, and only one big sweeper. Austria, on the other hand, was a great aero course, and with the way they score economy, the top combustion cars are only going to score 50 points in fuel anyway.

I could say the aero made us a second/lap faster in autocross and endurance, and cost us 0.2 seconds in accel and 0.2 liters of fuel, but those numbers are speculation, not fact. I expect we will be analyzing the data from FSG and plugging numbers into our sims to try to determine if our car would have scored more points without the aero. If GFR runs without aero at FSG next year you'll know the results of that analysis. http://fsae.com/groupee_common/emoticons/icon_smile.gif

As for the second part of Scott's question, I think aero is more effective on a light single car. The aero single can carry more speed through the corner, so the lack of acceleration on the straight doesn't carry as much impact on lap times. All qualitative, of course, we don't do sims on 210 kg cars. http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif

[bmin]

If we look at your last car, we already saw that your drivers set the fastest laptimes. So did you again, but lost points in acceleration and cost. Not even mentioned the money and hours of work you spent on this. We'll be excited what you are going to do the next year

[Sormaz]

Originally posted by bmin:
If we look at your last car, we already saw that your drivers set the fastest laptimes. So did you again, but lost points in acceleration and cost. Not even mentioned the money and hours of work you spent on this. We'll be excited what you are going to do the next year
Interesting point. I guess it depends how you view the competition - are you trying to achieve the highest overall performance allowable within the rules or are you simply trying to perform better than everyone else that is competing? Each approach will merit the same reward, however the latter is going to be very difficult to handle as design criteria.

The quote about "winning at the slowest possible pace" comes to mind, however I don't quite like the implications of those ideas with the type of competition we have here

[whiltebeitel]

Originally posted by bmin:
If we look at your last car, we already saw that your drivers set the fastest laptimes. So did you again, but lost points in acceleration and cost. Not even mentioned the money and hours of work you spent on this. We'll be excited what you are going to do the next year

Comparing FSAE Michigan and FSG between GFR, TU Munich, Stuttgart, and U of Michigan (Ann Arbor), GFR put an extra 20-30 points on their serious competition over AutoX, Acceleration, Endurance, and Economy with the aero package (This is the only change I can prove). Economy scores were not really any different with the new formula between the competitions.

[bmin]

@ whiltebeitel

why not including skid pad in your calculation? because then its not that clear to decide.

[theTTshark]

Originally posted by ben:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scott Wordley:

Was that Sam Collins from Race Car Engineering mag commentating during the final four cars at Formula Student Germany? Pretty funny if it was, having gone from this opinion:

http://www.racecar-engineering...gs/wings-and-things/ (http://www.racecar-engineering.com/blogs/wings-and-things/)

To... in reference to GFR's performance...

"this is extremely harsh on all the other non-aero design teams"


Opinion pieces on engineering with no data to support them are basically the most pointless form of journalism - not surprised he backtracked when confronted by a nice shiny car with wings winning.

As has always been the case a wing car can do well provided it's engineered well, but a well engineered non-wing car can still do well also - that's the beauty of the regs.

What people also forget when writing for technical magazines is that it's not a pure racing event - the academic exercise of doing wings (particularly if you have facilities like Monash) is entirely within the spirit of the competition.

Ben </div></BLOCKQUOTE>

Sam should come to Lincoln at the end of August for Solo Nationals to see why aero is needed on real auto-x courses. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[whiltebeitel]

Originally posted by bmin:
@ whiltebeitel

why not including skid pad in your calculation? because then its not that clear to decide.

Look at the skidpad results from Michigan to the european events. GFR did not significantly change their position relative to the other teams, other than the less-than-ideal result at FSG, therefore, I felt no real trend was expressed in this event due to the aero package.

[EHog]

I find it entertaining that people are acting like GFR is the first team to run wings... Its kind of offensive actually! They obviously started with a very good car before the addition of aero.

As Bob said, the only way to know the answer is if they ran all dynamic events with and without aero. Even then, you would have to assume the drivers are NOT A VARIABLE (hehe). All this speculation is very un-engineering-ish.


So maybe I should have kept these thoughts to myself instead of posting them on the interwebs... Ah well, have fun being angry at me!

[whiltebeitel]

Originally posted by EHog:
I find it entertaining that people are acting like GFR is the first team to run wings... Its kind of offensive actually! They obviously started with a very good car before the addition of aero.

As Bob said, the only way to know the answer is if they ran all dynamic events with and without aero. Even then, you would have to assume the drivers are NOT A VARIABLE (hehe). All this speculation is very un-engineering-ish.


So maybe I should have kept these thoughts to myself instead of posting them on the interwebs... Ah well, have fun being angry at me!

Drivers are indeed a huge variable, and the reason I chose GFR is mainly because they went form a car without wings to a car with wings in the same season, using the same drivers, competing against similar teams.

There are tons of other variables, but I think that you can get a order-of-magnitude estimation of the benefits of a well-built aero package that's been tested vs. the time invested in it.

Sam at RCE has a valid opinion for less developed teams with limited resources. If you can spend the time you'd otherwise dedicate to a aero package on driver training and suspension testing, you may find a points delta larger than the aero package offers.

Some may find that they have the resources to pursue such an aero package, as they have diminishing returns on other avenues to get more points.

This is an engineering competition, but it also a project management competition. Each team should know their resources and their limitations, and then execute a plan that lets them "engineer" the best result in the end, be it by design, manufacturing, and validation.

[Mbirt]

Too bad ETS wasn't at FSG. Based upon their performance in California, they would have been knocking on a top-5 accel performance and descriptions of the auto-x/endurance course make it sound even more friendly to a non-aero single-cylinder car than the course at the comp which they won.

[TMichaels]

Just in case you are interested:
We posted on-board footage of the autocross and endurance track layout prior to the dynamic events:
http://media.formulastudent.de...3#1414772418_Q8256Xc (http://media.formulastudent.de/FSGTV/FSG-2011/Miscellaneus/18412580_LFMDp3#1414772418_Q8256Xc)

Regards,

Tobias

[bob.paasch]

Originally posted by Mbirt:
Too bad ETS wasn't at FSG. Based upon their performance in California, they would have been knocking on a top-5 accel performance and descriptions of the auto-x/endurance course make it sound even more friendly to a non-aero single-cylinder car than the course at the comp which they won.

I talked with 3 of the ETS guys at the Mahle party, they were very disappointed that things didn't work out such that they could bring their car to FSG.

I agree it would have been very interesting to have ETS at FSG, the performance of GFR11 without the wings and ETS11 are very similar.

[Thrainer]

Interesting discussion. To add a point, I would like to mention that the competitors change the results. This year in Europe, I didn't see a fast single challenging the 4-cyl and GFR's aero single (Bath and Oxford Brookes come to mind, but they were out of luck). Remember FSG 2010, when Delft was faster than GFR and won fuel efficiency.

Each concept has its weaknesses and strengths. When certain concepts are not represented well, this changes the results of the competition. E.g., the fuel event theoretically is a weakness for the GFR aero car, but only compared to "Delft concept" cars.

I personally believe there is a lot of potential for teams that decide to follow the "Delft concept" or something similar. At FSA 2011, Erlangen beat all the top teams with 4-cyl cars.

Concerning aero, I believe ressources is a big issue, but also understanding the car and testing time are crucial to being able to use the potential. I only followed Monash and GFR, so can't speak for all aero teams. It seems to me they don't change too many variables (e.g. chassis, drivetrain, aero) from one season to the next.

Regards
Thomas

[Scott Wordley]

Thrainer, this year we have an all new engine, chassis, suspension, wings... everything.

I actually think it is pretty smart, where possible, to carry over some parts from year to year (whilst always building a new chassis). It can back fire on you though because it is easy to lose the expertise required to design and build the parts that you end up carrying over, with the result that you make the same old mistakes over again, and respond with the same knee jerk reaction, for a year or so after.

[RANeff]

Scott, if you dont mind me asking, how much do those new wings weigh? They are... Interesting http://fsae.com/groupee_common/emoticons/icon_wink.gif

[bob.paasch]

Originally posted by Thrainer:
Interesting discussion. To add a point, I would like to mention that the competitors change the results. This year in Europe, I didn't see a fast single challenging the 4-cyl and GFR's aero single (Bath and Oxford Brookes come to mind, but they were out of luck). Remember FSG 2010, when Delft was faster than GFR and won fuel efficiency.

Each concept has its weaknesses and strengths. When certain concepts are not represented well, this changes the results of the competition. E.g., the fuel event theoretically is a weakness for the GFR aero car, but only compared to "Delft concept" cars.

Exactly why it would have been great to have ETS at Germany. In terms of performance, they are closer to a "Delft concept" than pretty much anyone else right now. ETS only used 2.3 liters of fuel in California while winning endurance.

In my mind, it's probably more accurate to refer to this as the "RMIT concept." They were successful with it before Delft. http://fsae.com/groupee_common/emoticons/icon_smile.gif Or perhaps team neutral: "ultra-light concept."


I personally believe there is a lot of potential for teams that decide to follow the "Delft concept" or something similar. At FSA 2011, Erlangen beat all the top teams with 4-cyl cars.

Thomas, as you know, building a sub 150 kg combustion car is not easy (about like building a 180 kg electric car http://fsae.com/groupee_common/emoticons/icon_smile.gif ). I would never recommend this route for a low or mid-level team. But for those teams that have proper management in place, these cars have the potential to score a lot of dynamic points.


Concerning aero, I believe ressources is a big issue, but also understanding the car and testing time are crucial to being able to use the potential. I only followed Monash and GFR, so can't speak for all aero teams. It seems to me they don't change too many variables (e.g. chassis, drivetrain, aero) from one season to the next.

"...they don't change too many variables..." is probably inaccurate. Every system on the car gets refined every year. We spend a lot of time and effort in analysis and testing of our existing systems, trying to understand what we have before making even minor changes to a subsystem. We do try to limit the major vehicle system changes to one or two big ones a year.

A little history:

2007 OSU ran a 4 cylinder steel frame 13" car weighing 215 kg.
2008 OSU did a major suspension/chassis redesign to drop to 10" wheels, and weight reduction everywhere to drop to 180 kg.
2009 OSU redesign: Honda CRF450 and a front half CFRP monocoque. 150 kg.
2010 GFR redesign focus was the full monocoque. And building a global organization, a global supply chain, and two identical cars. 145 kg.
2011 GFR redesign focus was aero and an electric powertrain.
2012: ?

[Luke Phersson]

Originally posted by RANeff:
Scott, if you dont mind me asking, how much do those new wings weigh? They are... Interesting http://fsae.com/groupee_common/emoticons/icon_wink.gif

The total wing package hasn't been finished (should be mounted in a week or two), but it's expected to be around 10-12 kg - approx the same as the 2010 package but a lot bigger. Every year we've been improving our manufacturing techniques, the profiles alone (including an extra one for the diffuser) only weighed in at ~5.3 kg. Some photo's of the profiles in this facebook album. (http://www.facebook.com/media/set/?set=a.238908466130413.63278.185745901446670&type=1)

[Rex Chan]

Hello everyone!

Just though some people might like to know what we're (Melbourne Uni/MUR Motorsports) up to: Team 2011 is in the process of adding wings (borrowed from Monash) to the 2011 car. The car went to comp (FSAE-A 2011) just last month, and now it's time to have some fun.

Melbourne Uni 2011 with (old) Monash Wings (http://www.facebook.com/media/set/?set=a.10150503355103036.377339.559588035&type=3)

Basic car info (can be found eleswhere on the internet): 4 cylinder, E85, dry sump, steel spaceframe, spool, Goodyears, Ohlins.

The driver for wings was me thinking it would be fun/cool, and Steve Shalders (2011 comp driver) driving the 2011 Monash car (with rather large wings/aero) at the Driver Swap at Bryant Park. Monash Motorsport have very kindly lent us some wings, so it's only fair we put up info as we go through this interesting process.

We're hoping to do unsprung wings front & rear, but this might change, depending on if we get the stuff to fit.

We also plan to quantify the changes, so there will be data up when we get it on track. I'm mainly thinking speeds through slaloms and lane changes. We don't have fancy gear to measure downforce, but suggestions on how we could figure out how much of an effect its having would be great.

[Rex Chan]

I am in the process of making end-plates and mid-plates tonight, out of alum honeycomb. Does anyone have good ideas on how to finish off the edges? It's about ~12mm thick, so the raw edges could do some damage.

[mech5496]

Rex you can use sealing tape (the stuff used for sealing vacuum bags) covered with electrical tape. It worked pretty well for us, plus it looks fairly neat... Waiting your thoughts on aero advantages/disadvanatges!

[Will M]

Rex,

If you have some micro balloons you can make a nice, light weight, easily sandable putty to round off and seal up the edges. Just be careful to breath them in or get them on your skin.

[Rex Chan]

Thanks for all the (quick) replies!

I've always been of the view that we (Melbourne Uni) shouldn't do aero (don't need it to make your car work, so too much resources allocated for a new team; we have 100% new teams every year, due to it being a final year capstone major project).

However, it must have some effect. This is what we are having a look at right now. Also, it will give us a reason to use the powerful 4 cylinders: more power = more drag we can endure = more downforce we can get. I know there's a Fuel Economy event, but that's not the whole comp. We don't run lapsims/points sims, so that's the best answer I can give you on what I feel about aero.

Everything being equal, I feel that wings/aero must provide some benefit to laptimes (not necessarily points). However, in FSAE, things are not up to that level yet (and maybe never will be, and maybe should not be). Therefore, what makes your car fast or your team score points has a lot to do with your team. For example, many types of cars have been fast/scored well at the past few comps (Aus, or iternational).

What we're doing here is just trying to make our 2011 fast(er).

[Lorenzo Pessa]

Hi Rex,

have a look at water temperature when running the car with that front wing!
Are you going to measure drag with a coast down?

I'm waiting for your results!

[Rex Chan]

Lorenzo: I've thought about cooling, and the only thing I can do to this car is to remove the restrictive sidepod completely, and duct the thermofan. It's currently just sitting on the back of the radiator (no shroud). This should make the most of the fan & radiator (no shroud heats up slower, but fan is less effective; shroud makes fan better, but restricts vehicle induced airflow).

I've not looked into coast down, but sounds like we could do it (though won't that also depend on rolling friction of tyres + driveline?). Overall though, I'm not too concerned with drag; I'm after (balanced) downforce.

[Lorenzo Pessa]

Originally posted by Rex Chan:
I've not looked into coast down, but sounds like we could do it (though won't that also depend on rolling friction of tyres + driveline?). Overall though, I'm not too concerned with drag; I'm after (balanced) downforce.

I was only curious! :-)
About rolling friction you can perform some run at low speed (starting at 15-20 km/h) when v^2 is not so important. Coast down is a really expensive test in terms of time (many run to obtain decent data).
You are right if you focus on other stuff now.
Maybe with your next winged car...

[whiltebeitel]

Originally posted by Rex Chan:
We also plan to quantify the changes, so there will be data up when we get it on track. I'm mainly thinking speeds through slaloms and lane changes. We don't have fancy gear to measure downforce, but suggestions on how we could figure out how much of an effect its having would be great.

Rex, if you do sprung aero, you can do a simple semi steady-state run, going from low speed to high, and compare the shock travel with force to get a basic idea. Strain gauges on the push/pull rods would also accomplish this.

Heck, strain gauges on the rods that support the wings for unsprung mounting could be used to quantify the downforce with a couple of good FBDs!

[Chapo]

Rex,

You could always unbolt the wings and do a few medium/high speed coast downs and then bolt the wings back on and do the same things and directly compare the difference. That way you dont need to worry about the rolling resistance (I am assuming that their wings are nice and light and are not signifigantly going to increase any rolling resistance in comparison to the aero drag side of things). That way you have two very real numbers of the clutch in deceleration of the car and the difference can be attributed to drag.

[Chapo]

Correction to my last: while the wing weight should have minimal effect on rolling resistance their downforce will probably affect it.

However coast down testing with and with out over the same speed range will give an indication of the power that they absorb including any losses from increased rolling resistance due to higher loading of the bearings and tyres.

[Rex Chan]

Hi guys!

Just another update, and question: I've (finally) got the front wing assembly all done. There's still some small things to do, but it looks like a front wing now. Here's some pics of it sitting on the ground in front of the 2011 MUR car.

MUR 2011 car with front wings (almost) done (http://a7.sphotos.ak.fbcdn.net/hphotos-ak-ash4/396384_10150516608228036_559588035_9268566_1127099 22_n.jpg)

fb photo of front wing on the ground (50mm ground clearance when mounted) (http://www.facebook.com/photo.php?fbid=10150516608228036&set=a.10150503355103036.377339.559588035&type=3)

The next thing is to figure out how to mount it; we're going for unsprung (directly onto the uprights). Does anyone have advice or pictures?

[Rex Chan]

Hello all!

If you haven't seen on facebook, we got access to the Monash Wind Tunnel on the 9th Feb 2012, thanks to Scott Wordley. So we got our car/wing combo wind tunnel tested and improved on by the awesome wind tunnel/aero guys from the Monash FSAE team.

There were quite a few cameras/videos there, but below are links to the ones my camera took:

Monash Wind Tunnel (Melbourne Uni 2011/Monash Wings) (http://www.facebook.com/media/set/?set=a.10150553873123036.384075.559588035&type=3)

Video of Smoke Flow Vis on the Wordley (front) Biplane (http://www.facebook.com/video/video.php?v=10150555282398036)

Best run: CLA = 3.0, 46kg@60kmh DF, ~280N of drag, aero balance 43% from front