Caster and the upright

[flavorPacket]

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

Note my editted [sic] post. Also, definitely no "great intellect", just a lot of long hours spent mostly in libraries reading old books (not in the education "system").

Z </div></BLOCKQUOTE>

Exactly: Reading, and not building cars. That's Timo's point.

It called Formula SAE, not Formula Abstruse Suspension Theories with Limited Real World Application. These students need to build cars.

The real world doesn't work if everyone is an intellectual superstar and thinks the boring, hackneyed stuff is beneath them. The simple truth is that most engineers are not capable of deriving the equations they use every day, and the uglier truth is that they don't need to and probably shouldn't, because it's a waste of time and money.

There are many more things to learn in FSAE than how to derive equations. Given the limited time that students have, some may choose to learn other things, while others may have to learn other things out of necessity. We can't all sit in ivory towers, even if we prefer to!

-Ryan

[Z]

Ryan,

"Exactly: Reading, and not building cars. ..."

Tsk, tsk... Such an unjustified assumption.

But it is quite common. Last time I berated the poster for being too lazy to do his homework. This time, in the interests of diplomacy , here is some help: Find [Z Africa] (it's not the only car, just the first "grown-up" one).
~o0o~

"The real world doesn't work if everyone ... thinks the boring, hackneyed stuff is beneath them...
We can't all sit in ivory towers..."

Hmmm...? So a simple, to the point of being crude, "brown go-kart", with a single-speed single-cylinder drivetrain, and beam-axles each end ..... is an impractical, exotic creation, dreamed up in an ivory tower???

On the other hand, a car with unnecessarily complicated double-wishbones-with-push/pullrods-and-rockers-everywhere IS, in fact, necessary, because, err..., the "boring, hackneyed stuff is beneath"..., err..., umm...

Nope. Sorry. I just don't get it???
~o0o~

"The simple truth is that most engineers are not capable of deriving the equations they use every day,
and the uglier truth is that they don't need to and probably shouldn't, because it's a waste of time and money."

My experience of "the truth" is seeing far too many, often quite senior, engineers pulling equations out of the back of books and using them where they are simply NOT valid. (Saved, of course, by SF~10+)

All these equations are derived on the basis of a lot of simplifying assumptions, usually set out on page 1 of the particular chapter, and which few working engineers bother to read. The point of getting students to derive the equations, at least once in their working lives, is to expose the students to these assumptions. Any use of the equation outside of its valid assumption range can waste a lot more than just "time and money".

Too many examples to cover here ... but an amusing one was the "rising star" structural engineer at a civil engineering company I briefly worked for. He produced reams of calculations for the roof of a chalet in the Oz Snowy Mountains, but unfortunately mis-used one of the equations. The first time it snowed the roof caved in! (Fortunately, it caved in slowly with the rising snow, so no injuries.)

Z

PS. "editted [sic]" And there are a lot more! My excuse is bad eyes, and, err..., I'm too lazy to figure out how to turn on (?install?) the spell checker. Or to go back and correct them.

[trave916]

In the interest of finally just ending this discussion , which I have become increasingly annoyed by, I will leave you, Z, with the final comment (as I am sure that a person such as yourself will not be able to resist posting after this. In ordr to actually be the last post). I came on here for advice from others (which I recieved) ; but was also belittled by someone not worth my time. So thank you all for this experience, as I am finished with our suspension and ready for MI. So go ahead Z, have your say.

[Kevin Hayward]

The design process is merely a framework around reasoned decision making. One of the most important aspects of effective complicated design is knowing which decisions are important and which aren't. The best path towards developing this skill is to have a strong foundation in the fundamentals of mathematics and science.

While I would not recommend Euclid and Newton as the first books to read regarding suspension systems, they wouldn't be far down my list. We are talking about the foundation of geometry and motion. These are definitely not abstract texts with no relevance. You would be surprised, especially with Euclid just how applicable it is.

It is misleading to newcomers to say build don't read. There are suspension designers in FSAE that find the time to design, manufacture, test, and read (a lot). In order to understand vehicle dynamics and suspension design you will need to have your head in a heck of a lot of books.

FSAE is incredibly competitive. Learn or Lose.

...

To ground this back to the original post. Lets look at the example of adjustability. We have a certain amount of test time for each car. It is incredibly limited even for the very well organised teams. That means there will only be a certain small amount of car setups that you will be able to try. What do we make adjustable?

If we know the importance of different parameters from a fundamental understanding of the motion and forces (including tyre modelling) we can have a pretty good idea. Caster is likely more important to adjust than KPI. Camber more important than kinematic roll centre. Do we want caster to adjust independently of caster offset? Camber independent of KPI?

A little bit of reading and ivory tower design can save a lot of track testing and mistakes.

...

Z is argumentative and can be incredibly negative in his posts, which does not help his cause. I have had more than one online fight with when he was first posting. But please do not disregard some of what he is saying just because you are unlikely to enjoy his company.

Kev

[The Stigg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">My experience of "the truth" is seeing far too many, often quite senior, engineers pulling equations out of the back of books and using them where they are simply NOT valid. </div></BLOCKQUOTE>
This is by far the best sentence in the whole Topic

It's quite easy to build correct mathematical models - but it's incredibly hard to formulate valid ones for a given problem.
There is a reason for the fact that about 80% of all fundamental mathematical and physical models are build upon empirical research.

BTW. We tried to test the whole "roll-centre migration" shizzle. to be honest at the end we were not able to measure a significant difference in lap time performance. But in this context we learned a lot about how the kinematic layout affected the stiffness of the overall system. That gave us the possibility to increase the stiffness to weight ratio and significantly increase lap time performance.
In vehicle dynamics "~everthing" is interdependent - and this is a chance. Even if you concentrate on a single parameter you are able to learn a lot about the other ones - and if you are lucky enough you pick one of them that significantly improves the performance.

Andy

[flavorPacket]

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

Tsk, tsk... Such an unjustified assumption.

But it is quite common. Last time I berated the poster for being too lazy to do his homework. This time, in the interests of diplomacy , here is some help: Find [Z Africa] (it's not the only car, just the first "grown-up" one).
~o0o~

</div></BLOCKQUOTE>

Erik, please don't misunderstand my point. I have a great respect for theory and its proponents, such as yourself. I hope that you already know this from previous discussion.

The scope of my response is far more limited than you inferred. I was not saying that you haven't built cars, but rather that your concept of a 'proper education' is comprised of much more than a capability to derive equations. While this is an important skill, it is not the only one needed to be an excellent engineer. In this thread, you lament that engineers can't start from first principles, which, I agree, is a serious issue. What I find more serious in everyday life, however, is how many engineers can't get a damn thing done on time and on budget (can you tell I'm in management now?).

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Hmmm...? So a simple, to the point of being crude, "brown go-kart", with a single-speed single-cylinder drivetrain, and beam-axles each end ..... is an impractical, exotic creation, dreamed up in an ivory tower???

On the other hand, a car with unnecessarily complicated double-wishbones-with-push/pullrods-and-rockers-everywhere IS, in fact, necessary, because, err..., the "boring, hackneyed stuff is beneath"..., err..., umm...
</div></BLOCKQUOTE>

I never said that your vehicle concept was 'ivory tower'-type stuff. If I built another formula car, it would have 2 beam axles and 2 dampers, and that's it!

When I get the chance to mentor my old team, I tell them to throw out their photos of F1 cars and go look at a 2CV and a Merc A/B class rear end...we're not so different, really, I just need to make a profit!

Ryan