Effects of rule changes

[bob.paasch]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by theTTshark:
I normally wouldn't write a response this long but I find that your last paragraph is a bit condescending (maybe not in intent but certainly in writing over the internet), so I feel especially driven to write a full response. I have no problem with someone disagreeing with my opinions regarding Formula SAE course design (or anything for that matter because at the end of the day everything is just an opinion except for the basic rules of nature), but we're always going to have people complaining about this and that especially in a competitive event like racing. It is not our job as engineers to say to those complaining that they do not have the right to complain, but it is our job to investigate and discuss these outside options to potentially find solutions to problems we hadn't thought of ourselves. I find that in every complaint, there is at the bottom of it, a problem, even if it is microscopic. As I have discussed above, the courses are what they are not because of the rules, but because of poor course design and implementation. At it's core this is indeed complaining, but on another level this leads to a discussion about where the future of courses can lead even within current rule sets. Which could lead to courses that are arguably easier for everybody to drive. I think the point here is, yes we all can't have it our way, but we are all entitled to our opinions. That's why I'm so interested in why you believe that my opinion should be silenced.

BTW, I believe that at least on a dynamics level we have proven that we can win or come close to winning on these autocross tracks, as your team has as well. </div></BLOCKQUOTE>

I'm sorry that you felt my last paragraph was condescending, that was not my intent.

For many years the FSAE rules read differently:

"1.2 Vehicle Design Objectives

For the purposes of this competition, the students are to assume that a manufacturing firm has engaged them to design, fabricate and demonstrate a prototype car for evaluation as a production item. The intended sales market is the nonprofessional weekend autocross racer...."

Some people complained about the premise. Some, like you, felt the FSAE autocross course should be representative of an SCCA course. Others felt fuel economy/efficiency an unnecessary part of the competition, after all, weekend autocrossers don't care about fuel economy.

What did SAE do? They dropped the above wording, and replaced it, making the purpose of the competition explicit. You are designing cars for FSAE dynamic events.

Of course they kept the "weekend autocrosser" premise for the presentation, the market for selling cars to other FSAE teams is pretty small (actually, given the rules, precisely zero ).

To tell the truth, when I think of the cars that Kansas has brought to competition, I see cars that are designed to win FSAE competitions. They also happen to be good at SCCA autocross. Not the other way around.

Now, back to our regularly scheduled pot stirring.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Z:
So, all FSAE aero students;

1. Get that picture of the "high rear wing" out of your minds.

2. "Streamline" your car (good for Fuel Efficiency ). Try a central cigar shaped fuselage, and add four tear-drop shaped wheel-pods at the corners. (And as long as there is nothing specific against these wheel-pods in the rules, DO NOT accept any arbitrary "spirit of the rules" bulldust bans from the scrutineers.)

3. Generate ALL your downforce from an "aero undertray". This approach is relatively lightweight, it lowers CG, and it generates negligible drag for tyre popping downforce (the rotating wheels will give more drag).
</div></BLOCKQUOTE>

Easy to pontificate from the armchair, but in practice, very difficult to implement. Aero undertrays on FSAE cars are complicated by:

1) inability to use any kind of side skirt to seal the sides
2) typically rough FSAE autocross and endurance surfaces that cause a lot of variation in vertical distance to ground for sprung undertrays
3) nasty vehicle dynamics considerations for unsprung undertrays
4) high yaw rates means that when you need the downforce, the air is coming in at an off angle. This complicates simulation (you now need a full car model) and becomes nearly impossible to physically validate under controlled conditions.

Now back to the original question:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kevin Hayward:
I thought I would post this as some positive feedback. It appears that the recent changes to the rules have improved FSAE quite a lot. I am mainly referring to the aerodynamic changes allowing sharper trailing edges, more plan area, and moving wings. A couple of main design considerations have changed:

- After removing most of the advantages for 4 cylinder engines through more points to fuel economy, aero returns some of that advantage by allowing teams with more power to take advantage of more downforce (due to being able to carry more drag). The recent changes have made it possible for cars to have too much drag relative to the power, which is a good thing. This might have a side effect of more teams trying to do custom engines.

- Aero development simply can't be ignored now. While teams may not decide to make aero packages some of their competitors will. As a result teams almost by default have to consider whether or not to run aero, rather than dismissing the possibility all together. Aero should be more prominent in design discussions. This is good as a fundamental area of mechanical engineering is in the forefront of students minds.

- for cars that go aero weight is now even more important, given that your downforce divided by your car weight will be the grip modifier.
</div></BLOCKQUOTE>

In my opinion, the new aero rules go too far. I think there was already a substantial advantage to aero under the old rules. Most teams declined to do aero due to logistical considerations. Under the new rules, again IMHO, aero is going to be necessary (but not sufficient) to win a major competition. The better teams will adjust, the lesser teams will fall further behind. Anyone can run CFD, but there will be an even larger advantage to teams with wind tunnel access.

That said, we're of course working on bigger wings.

[Kevin Hayward]

Bob,

That last sentence will scare a lot of teams. I guess we are all secretly hoping that GFR fall into the group of successful teams that fall due to not wanting to change their winning formula.

Kev

[Scott Wordley]

Going way back to Kev's comments, I agree on nearly all points you made.

The rest of the field does make a big difference to the spread and should be accounted for. The margins do narrow with a very fast 4 taking down accel. I still think there should be a reasonable margin in the fuel used between a 4 and a single produced by the same team, for us it was a little over 1L. I think it would probably be similar for most teams, even across different levels of engine development expertise.

I completely agree that teams can still score very highly (and even win on occasion) with a car that is very far from the theoretical optimum, but I am not considering those factors in this discussion. Just trying to imagine what the highest scoring car that you could realistically build for this competition would look like, without concerning ourselves with boring limitations, timelines and resources.

Z, I have to agree with some points and disagree on others. While "high downforce does not have to imply high drag" all too often it works out that way due to the other restrictions we face in the design of these vehicles (package space, integration, CG height issues, weight etc). For example, rather than use a multielement wing (CL =4) I could run a single element wing (CL =1) but I would have to make it maybe twice the plan area and double the span. It just not possible within the rules, and besides it would weigh more and increase our cg height (if it were a high mount rear wing). When designing aero for these cars you quickly realise that you are designing less for "efficiency" and more for "effectiveness". A wing that is twice as efficient is frequently half as effective.

You are correct about Carroll Smith saying "Aero cars will dominate", about 10 years ago. He was talking about our 2002 car (the first with full diffuser and unsprung wings) when he said it. I recorded it and put it in this video(about 2mins in) if anyone is interested in watching it: (excuse the drum and bass, or rock out... your choice)

http://www.youtube.com/watch?v=dkuwIW_Wp3U

I'm pretty sure I met you (Z) briefly you at this comp as well, I had a Blue mohawk at the time (like the entire rest of the team!)

Speaking of high mounted wings, they are a necessary evil. I like the aero ideas you put forward with your twin beam wing design, particularly the front but I seriously doubt the rear is going to make much DF as it is in the wake of the front. If we get a chance we will run some quick sims on it to check. The flow coming off the front wing ends up at driver head height, leaving only dead air near the rear wheels. This is evident in the problems aero teams have getting radiators to work down there. It also means the diffuser doesn't work as good at the back. If you cant bring clean air in from the sides, you have to go high (as you cant go wider). The more aggressive your front wing the higher you have to go which means the more front you need etc etc. I predict biplane front wings will make an appearance in the future to try and remedy this imbalance. At first glance it may appear that we are simply mimicking real race cars, but in fact we don't have much choice (or none that I can see).

We have thought about Wheel pods in the past, but don't run them because the front wing covers the front wheels and the radiators cover the rear wheels.

Would you believe we even thought about the tailfin/steerable sails that you proposed, way back in 2002. We reasoned that any sail side force created would incur an equivalent drag to that of a traditional down forcing wing. The downforcing wing however has the advantage of the CoF multiplier, hence is more efficient way to "spend" that drag. Common sense kicked in when we started thinking about optimising it through dynamic roll angle adjustment (as discussed here) and we decided to focus on more pressing problems of getting a car built and tested!

Drag Reduction Systems may in fact be a wank. On the other hand they may be a very easy and reliable points gain, for an investment of $200 and about a weeks work. The devil with this one is in the details, which is why we have built and tunnel tested a system and are now experimenting with it on track. In our first test we found it was super easy for the driver to actuate it via a button on the wheel, so we will not bother with any computer logic control like Sooner used. The car pulls really hard in a straight line again (for the first time) which is great. If we get a track with a lot of straight lines (or softly curving ones) then I cant see how it wont be a benefit. Consider that with full wing we are hitting terminal speed in SLALOMS of around 16m spacing.

Unlike F1 we can actuate as much of our wing as we like (front included) and for as long as we like. Granted our straights are not as long, but I think we would use it for a larger proportion of the lap than they are allowed. Hardly mindless mimicking but I understand you are just stirring us up. In this respect I agree with Mike's quote:

"just because people don't post all of their calculations, doesn't me they didn't do them"
I'm sure Maryland have been through all this and ten times more, but don't necessarily want to talk about it as much as some.

I agree with Bob's comments on the problems associated with under trays. We are trying to validate (or otherwise) ours at the moment and it is a nightmare, even with 64 channels of high speed pressure tapping. If we manage to make something of the data it might appear at the SAE congress in 2013.

Also I think Bob's comment is spot on:
"Under the new rules, again IMHO, aero is going to be necessary (but not sufficient) to win a major competition."

The thought of GFR coming back with bigger wings is going to keep me awake at night...
Perhaps non-aero teams should start sharpening their knives? :P

Scott

[Kevin Hayward]

Scott,

Great points as usual. I think the question shouldn't be 1 vs 4 cylinders, rather it should be light vs. heavy engines. The highest performance FSAE engine is still to be made. Resource allocation issues may mean it never gets made.

We still saw in Australia that UWA outscored Monash on dynamic events. Both teams had cars that had been running for quite a while, both with great driver teams, which if we counted all competing drivers I would say Monash's was better. I still agree that the Monash concept is probably theoretically better given the points sims we have run.

The fuel use difference is another interesting question. I would accept about 1L between a single and a 4 with both on full tilt. However the 4 teams are moving towards conserving fuel in endurance, while the singles have more need to wring the power out. I would say given different comp strategies the difference would be smaller. I think we saw some of this in Australia, and some with what Stuttgart has been doing in endurance.

We have had a brief look at the strategy behind different concepts and there does appear to be two main ways to gain a slight advantage:

1. Gain the points that the main competition ignores. Having a different car to the bulk of the main players in a given comp means you have a window to uncontested points.

2. Lead early. This both puts pressure on your competitors (forcing errors), as well as setting you up for any change in conditions.

At the moment this still favours the lightweight high aero car, which has the potential to lead early (being one of the higher performance concepts) and as well being the odd one out.

Still doesn't give an explanation for the UWA dynamic win in Australia.

Kev

[Z]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kevin Hayward:
... Still doesn't give an explanation for the UWA dynamic win in Australia.
</div></BLOCKQUOTE>
Kev,

Hmmmmm...., err...., maybe.... it's because they've got an.....
aero undertray???

Oh, yes...., and also a....
soft twist-mode???

(Yes, I know, that doesn't prove anything... )
~~~o0o~~~

And as Mike says, UWA are certainly not going to promote those ideas here, in public!

(Maybe I'd best shut up now. Sorry Pete.)
~~~o0o~~~

Scott, my mohawk is a lot greyer now.

Z

[Lorenzo Pessa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Z:
2. "Streamline" your car (good for Fuel Efficiency ). Try a central cigar shaped fuselage, and add four tear-drop shaped wheel-pods at the corners. (And as long as there is nothing specific against these wheel-pods in the rules, DO NOT accept any arbitrary "spirit of the rules" bulldust bans from the scrutineers.)

3. Generate ALL your downforce from an "aero undertray". This approach is relatively lightweight, it lowers CG, and it generates negligible drag for tyre popping downforce (the rotating wheels will give more drag).
~~~o0o~~~
</div></BLOCKQUOTE>

Z,
first of all I apologize because I didn't found the time to answer when you post your concept (ok, I also red several posts of this topic too fast! sorry, too busy at work).
I found it interesting but I not sure that aero package can work so well (there is a bluff body inside the wing and a hole between lower and upper surface). That's only a "chat", it need at least a CFD sim to find out what happen.

About you "aero undertray" don't forget that undertray and rear wing work together. You can improve your undertray performance with a rear wing.
I remember Sophia ran with an undertray and a rear wing.

The sail car is less foul as one can imagine. They are good if you don't need to steer so much. I'm not sure it would be easy to manage it on a FSAE track.
Is Russell Coutts eligible to drive a Formula SAE?

[bob.paasch]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kevin Hayward:
The fuel use difference is another interesting question. I would accept about 1L between a single and a 4 with both on full tilt. However the 4 teams are moving towards conserving fuel in endurance, while the singles have more need to wring the power out. I would say given different comp strategies the difference would be smaller. I think we saw some of this in Australia, and some with what Stuttgart has been doing in endurance.
</div></BLOCKQUOTE>

While Stuttgart has made significant progress, TU Munich is the team that has really trimmed their fuel usage this last year. 3,4 liters at FSG, and 3,2 at Michigan. But the single teams certainly aren't ignoring fuel. ETS won design at California last year because of their engine development. They won endurance whilst using 2,3 liters of fuel. That's still a liter and about a 30-40 point advantage over the most fuel efficient fast 4s.

I see Munich and Stuttgart have entered FSUK as E85 cars. That will give them another 10-15% in fuel.

[Scott Wordley]

Kev,

Consider that UWA actually used less fuel than us in Aus. I would also mention that the Aus track was particularly aero unfriendly this year. We are also a lot heavier than what is theoretically achieveable for an aero single, as it was our first time out with this package and we designed and built in 6 months. So on this basis I wouldn't necessarily consider Monash versus UWA as a fair comparison of these two "concepts".

I think there is much more room for improvement on our end, while I think the current UWA/Munich/Stutgartt cars are about as close to as good as a 4 cylinder non-aero cars can get.

I am pretty sure some of the good engine tech teams could comfortably go under 2L fuel used, if they switched to a single, possibly whilst running wings.

We are planning on going E85 as well, but didn't have time to get it set up for Europe. It does appear to provide a reliable increase in Fuel Economy.

Regarding the highest performance engine being yet to made made... if anyone thinks they can do better than the major bike manufacturers then please be my guest! Consider talking to teams like WWU, Melbourne Uni, Aachen(?) and Auckland who have gone down this route and see what their advice is. Look up their historical scores as well. Once you finish your bespoke engine please calculate the differential in points scored compared to what you achieved running an off the shelf engine, and then divide that by the amount of time, money and resources you have invested. Interested in what that "number" would look like and if it would be positive. Historically speaking, I think it is more commonly negative.

[Kevin Hayward]

Scott,

Please don't mistake my queries for an attack on the concept.

I agree that UWA's car is about as good as that current concept currently is and Monash are only at the beginning (especially with a new engine). I was genuinely surprised that UWA won the dynamics. Unless I am mistaken the last time the Monash concept (only with less aero and a four) went up against the UWA concept where both competed(2009), Monash was the comfortable dynamic winner. Clearly on average in 2011 Monash had the better driving squad based on lap times. We could probably say that UWA's engine was better developed, as was their mechanical grip. But on the other hand very few teams develop Aero as well as Monash. Did we see mechanical grip and engine development trump better aero? With further development I expect Monash would have a much better dynamic scoring car (which does worry me). But I also expected them to have the edge in 2011.

The track at Australia was ridiculous. They had a problem with getting barriers in time so designed the most twisty and cone filled course that has been run at Werribee. No team was more disappointed at this than ECU. On the other hand it does make a case for non-aero teams to be a bit happier with their design choices. Aero teams do want reasonable course design to perform their best. Monash also lost the dynamics on the back of hitting far too many cones. While the cone hitting issue of wings is not as bad as some would believe, it still exists.

I agree with the resource allocation arguments related to custom engines. But it doesn't change the fact that engine development is more valuable now. Aero has made weight much more important, and the rules have made economy more important. I would expect to see new engines at least in the form of heavily modified bike engines; maybe new cases with original head and internals. The main problem with existing bike engines is packaging, leading to increased weight. Engines are still worth less than mechanical grip and aero in terms of performance, but the changes to the rules have made it more inviting. If a team can find and manage the resources effectively they have a chance to pull out an advantage. I would have easily dismissed a custom engine previously, but now I wonder if a longer term design program might be worth it to teams, especially those that already have good engine development backgrounds. I don't think the small number of custom engines we have seen so far is anything but the early stages of this line of development.

Regardless I think we are in for interesting developments in the next few years, as it is pretty clear the goalpost has changed.

Kev

[Bemo]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Z:
2. "Streamline" your car (good for Fuel Efficiency ). Try a central cigar shaped fuselage, and add four tear-drop shaped wheel-pods at the corners. (And as long as there is nothing specific against these wheel-pods in the rules, DO NOT accept any arbitrary "spirit of the rules" bulldust bans from the scrutineers.)
</div></BLOCKQUOTE>

First of all the rules clearly say that the car has to be "open-wheeled". Of course there is a grey area were this starts and ends.
But what I'm really interested in is how you want to not accept if scrutineers don't allow it.
If they insist, it's against the rules you remove it - or you don't compete in the dynamics.

I wouldn't accept closed tear-shaped and steered covers over the wheels as they are clearly against the open-wheeled rule. Not just against the spirit or intend if a rule.