Does Anyone Know What the Heck is Going on at Goodyear!?

[NickFavazzo]

Originally posted by Rex Chan:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete Marsh:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Even then, as much as it would have been nice to have for competitive advantage, if you switch tires how much do you really have to change on your cars to re-balance it? A test and tune day (or half of one) perhaps, but I'd have a hard time imagining it being a total catastrophe.

Just my gut feeling.

Not just a competitive difference or balance change, the size and rates of the tyres are different making a direct swap not always OK. A REAL big problem for at least one concept I'm familiar with, and still a hassle with bodywork rules etc.

I notice the post from Goodyear does not totally rule out the possibility of another manufacturing run of the current tyre?

Pete </div></BLOCKQUOTE>

How much? </div></BLOCKQUOTE>

About 20mm on Diameter as well as being different width and different spring rates.

[Claude Rouelle]

To Jersey Tom an all,

One of my best employers was ORECA for which I was the Formula 3 chief race engineer many, many years ago. We won 100 % of the championships and more than 60 % of the races we compete in. After a while I noticed that race debriefings conducted by Hughes de Chaunac, the team owner, were always 3 times longer when we won race than we lost them. I asked Hughes why and he told me:" I want to know why we win. If we do not know why we win, we won't know what we lose"

That phrase has has been with me with for the rest of my career. In my own words it became "win, know why, win again"

I can't agree with the "build and test or with the "cope the best you can" with the tire brand change philosophy. Even less in FSAE which, let's remember, is a design and project management competition based on a race car, not a racing series.

As a design judge I expect the students to scientifically and objectively use their tire data, all the simulations tools and the recorded track data analysis to justify the tire choice they made, to show how they design and tune their car around that tire and what they would change if they had to do it again and WHY. It is not a disaster if they made an error, providing they can explain what the error was, what they should have done (or will do next time) to avoid it. Similarly I expect them to explain what they change in their car design and WHY if circumstances force them to switch from tire X to tire Y. Possible tire switch should have been part of a plan B anyway.

Here is an abstract of an interview on Ron Dennis (Mac Laren F1) in 1998: "... in fact, the needs of all Formula 1 cars are invariably served by the same technical exercise. The fact is that the car - and the kinematics of its suspension - must be developed hand in hand with the tire. As I indicated earlier, optimum results can only be achieved when the two sides are prepared to share their most secret and sensitive data"

In the "real" racing world, I have seen too often very good tire engineers and as good race car design and development engineers... but speaking together and not enough long term strategy and design of car around tires and vice versa. Believe me or not, I know some excellent ex FSAE students who joined race car design department of team attacking big challenges (such as Le Mans) where they have been asked to design the suspension kinematics ... without tire data! As Doug Milliken told me one day "they are asked to solve engineering problem ... without engineering data".

If they succeed they are good if they fail they are idiots. I disagree with that tactic. Even less in FSAE where students do have access to TTC tire data

It is not about winning; it is about knowing why. It is about the constant search for knowledge and best practice.

I can say that I am proud that my company customers have been winning race and championships in many different racing series for several years simply because as vehicle dynamics consultant we use and developed simulation and data analysis tools allowing both race tire manufacturers and race car manufacturers (or race teams) to get the best of each other information. That is also an approach and a methodology that we present in our seminars.

I know how much energy, money and time is often wasted by acting without thinking, designing without communication or enough understanding, testing without simulating, developing without attentively analyzing previous test data. I made that mistake too often myself.

Doing the best you can with a new tire around which the car was not necessarily designed? Sure: that is part of the challenge. Knowing WHAT to change and WHY; and prove it on the race track; THAT is the real challenge.

Students can still win the competition without necessarily giving brilliant explanations in the design event. Especially if they have good drivers and a reliable car. But that is not what prepare them for a good engineering career.

[Rex Chan]

I'm not sure I agree with this. If your aim is to win FSAE, and you can do that with good drivers and a reliable car (with not great VD understanding), then I would say you have successfully addressed the engineering problem.

[PatClarke]

Rex,

You are missing the point!

Pat

[Rex Chan]

Originally posted by NickFavazzo:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rex Chan:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete Marsh:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Even then, as much as it would have been nice to have for competitive advantage, if you switch tires how much do you really have to change on your cars to re-balance it? A test and tune day (or half of one) perhaps, but I'd have a hard time imagining it being a total catastrophe.

Just my gut feeling.

Not just a competitive difference or balance change, the size and rates of the tyres are different making a direct swap not always OK. A REAL big problem for at least one concept I'm familiar with, and still a hassle with bodywork rules etc.

I notice the post from Goodyear does not totally rule out the possibility of another manufacturing run of the current tyre?

Pete </div></BLOCKQUOTE>

How much? </div></BLOCKQUOTE>

About 20mm on Diameter as well as being different width and different spring rates. </div></BLOCKQUOTE>

Sorry - I meant to reply to Pete MArsh's post. How much for a set of D2704?

[MCoach]

Originally posted by PatClarke:
Rex,

You are missing the point!

Pat

Rex,

While you may have a point against the problem, it's in the right direction for the wrong reasons. If the car is pretty much settled and already designed around a different tire (as I am aware is the case in the upcoming Australia competition) then there isn't a whole lot of room to redesign and manufacture things. So, the problem becomes re-situate the car or change the product requisition strategy to match the current market (no new tires, dwindling supply of old tires).

As you've demonstrated, you've changed strategy and are clamoring for the last of the Goodyear tires.

Claude and Pat are trying to show that it's about tackling the engineering (and management) problem when they present themselves rather than trying to get around it with brute driving skill and a MIG welder...

[Mike Cook]

Wouldn't it be funny if you just switched the G brand with the H brand and your car went faster right out of the box. hmmm

[MCoach]

Funny you say that...

[Claude Rouelle]

Rex (and all passionate readers of this forum)

As Pat wrote, you missed the point.

So let's say you win FSAE. So what now? What if your brain is only as full as your conscience of not having done the best you could?

Let me tell you a story that may help you to understand what is in my mind.

A few years ago I ask a team suspension student during the design part of a competition in Europe what the critical damping was.

The student did not know. At all.

I am thinking "OK that the guy is a bit panicking, let's ask another one" Second one did not have an answer either.

OK so I think it must be my English or theirs and we have a communication problem. So I ask more students and soon we have 4 students involved in chassis and suspension + the "technical director" + the "team manager" 6 guys: still no answer.

So I asked "Do you have your design specification sheet here? " They had it. I showed them "look here it is written that in bump at 50 mm/sec you have 87 % of the critical damping on your front dampers? 87 % of what? " NO ONE COULD TELL!!

I insisted "OK you do not know what the formula is, that is OK but what does critical damping physically means" They would have told that if they push on their passenger car hood and release the effort and the car comes back at its initial ride height as quickly as possible without overshoot, and that was critical damping, that would have been OK but even no one of them could tell me that"

Sorry guys but whether you learn designing cars, bridge or aircraft you should at least have a vague idea of what critical damping is.......

So I went to ask several other questions such as basic definition of understeer and how they quantified understeer / oversteer in their tests but again no answer. How in that case do they quantify the progresses they made on the race track? Only with the lap time?

Well, believe it or not that team won that competition that year. And they even won a few more since. But still today they have a low knowledge of vehicle dynamics (or very low ability to express it) and they still can't really justify the choice they made in their car concept. They might be right but they do not know why.

Don't get me wrong: they won and they deserved it. The car looks really, really good on the track, bloody good drivers, a bit heavy but their manufacturing was superb and just looking at it, it did "inspire" reliability, lots of testing, and their organization is an example for the paddock. Much better in manufacturing (well with a lot of subcontracting...) and testing than in design, concept and simulation or data analysis.

But because there is more than the double of points in endurance than in design, in my mind it doesn't give them the right to ignore their weakness in justifications of their design choice.

Winning is good for the heart and the team spirit. Winning without knowing why is not so good for the brain. Or the soul.

If you do not know why you win, you won't know why you lose. See my point know now?

Well as I am bashing around students tonight and I can't sleep (jet lag) let me tell me another good one which occurred recently in last FSAE competition in Italy, which shows how poor the basic, basic knowledge of students who design suspensions sometimes can be. And which makes me... I still hesitate between laughing and crying.

Here was the dialogue
- What is the tire coefficient of friction?
- I don't know.
- Come on you should have me an idea...
- I really have no idea.
- Try...
- 0.4...
- 0.4? How many G (lateral) can your car pull in the corner?
- About 1.6 to 1.7 G.
- And you think that you can pull 1.6 to 1.7 G in corners with tires which have 0.4 of coefficient of friction?

The student looked a bit puzzled and you could see his bearings rolling... Then suddenly he looked at me and said:" Well I must be right right ... look 0.4 per tire and there are 4 tires so that makes 1.6! You see I wasn't too far off!

At least he made me laugh.

But he would have been a student of mine in any university I teach, he would have been told to come back next year or to chose another career...

Win. Know WHY. Win again.

[nick roberts]

Rex - Therein lies the complexity with the current competition structure. Winning this "engineering design competition" requires less engineering than one would think. Theoretically a team could rebuild the previous year's car, develop it for 3 months using only lap times to determine progress, completely bomb design, and still place very well. Sounds a little like Claude's example I suppose.

Arguably, testing and development are as much or more of engineering as the initial design work, but from my experience, vehicle dynamics should be very well understood if a team wants to obtain any useful results from their testing.

It all depends on which "engineering problem" you choose to address.


Mike - Sounds a little like our experience. ; )

Thankfully, after making the switch and immediately going 1-2 sec faster, we took the time to go back and figure out why. We feel like this work will be invaluable moving forward to actually design a car around the tires.


Claude - I'm curious. If you were a team leader in charge of managing a team, how would you structure the year? Which aspect of this engineering project would you prioritize? Assuming we have 10 months to design, build, and test a vehicle what would your target timeline look like?

Ours, regrettably, looked like this last year:
Design - 5 months
Build - 4.5 months
Test - .5 months


-Nick