Most difficult part of design

[Banacek]

Just as a bit of a survey, what subsystem of a FSAE car do you folks find takes the most mental effort to design? (drivetrain? chasis? aerodynamics for the Monash crowd?)

On a similar thread, would anyone care to share how their team effort is divided during the design process. (i.e. 30% chasis, 40% suspension...)


Banacek
"There's an old Polish proverb..."

[Banacek]

Just as a bit of a survey, what subsystem of a FSAE car do you folks find takes the most mental effort to design? (drivetrain? chasis? aerodynamics for the Monash crowd?)

On a similar thread, would anyone care to share how their team effort is divided during the design process. (i.e. 30% chasis, 40% suspension...)


Banacek
"There's an old Polish proverb..."

[fsae_alum]

I would have to say a good suspension design taking EVERYTHING (wheel rates, tires, track temp, shocks, bellcrank ratios, arb's, force analysis, upright design, packaging, anti-..., the list goes on and on) into consideration. For us it also proved to be the most time consuming!

In spite of...

[Bob Wright]

suspension is the tough one but the bit i usually hate the most is designing the bloody jigs to get all of it in the right places

Bob Wright
Monash University
Australia
http://www-personal.monash.edu.au/~fsae

[Charlie]

I don't know, seems like most of the aspects of the car can be extensively thought-out and painstakingly designed. And many can be knocked out easily (at the expense of quality). So I think the most difficult part of design is the one you decide requires the most effort.

As for workload, that depends on your team's strong points. if you have 3 people who are ver competent at chassis and frame design and integration, you are better off putting them on that then engine.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Engelbert]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by fsae_alum:
I would have to say a good suspension design taking EVERYTHING (wheel rates, tires, track temp, shocks, bellcrank ratios, arb's, force analysis, upright design, packaging, anti-..., the list goes on and on) into consideration. For us it also proved to be the most time consuming!

In spite of...<HR></BLOCKQUOTE>

I agree. You must consider the COMPLETE design of the suspension/steering system (except maybe shockies, rodends and bearings, etc), as opposed to the engine, which is generally a redesign of the fuel/air/elec "accessories".

Dont get me wrong, I know the engine is a tough job, but you are given a starting point to work from. With the suspension, you start with concepts, ideas, and maybe some data from previous years, if you are lucky.

I know its a simplified view, but imagine the task if you had to build the engine from scratch, including gears, pistons, port design....etc etc etc. THEN you'd hear those engine guys whinging about too much work !!!

Sam.

[David Kieke]

As I begin my 6th year of involvement in FSAE, the basic understanding of Milliken, Heisler, etc are somewhat distant memories, but the in-depth realization of their complexity re-occurs daily. However, in my eyes, those aren't the most difficult part of the design, in the purest sense of designing a physical machine to perform a given task, but are key elements (along with testing) to convincing the design judges that your team understands the engineering basics of race car design and that the reasoning behind your design decisions is sound.

Also I would like to add that setting up an engine, wiring it, troubleshooting it, and tuning it is a time consuming process, but doesn't fall under design. If we were to ever attempt to design and build our own engine, that would be the hardest system to design by a long shot.

Packaging and seeing the whole picture, those are the most difficult aspects of design. Designing single components or even smaller assemblies can be very time consuming but generally easier compared to the layout of the entire vehicle. As Colin Chapman said, the frame should be the last part designed and it's sole puropse is to connect the load input points in a stiff and stable manner. Unfortunately, the frame must be designed relatively early on because so much of the rest of the detail design is constrained by packaging or mounting to the frame, so there needs to be something to design them to. In this manner, the designer must understand all the parts that must be attached and where and how they will attach while developing the initial design.

Consequently, packaging is one of the most important features that separate the well-designed, and generally top-performing, cars from the rest of us. Unfortunately, elegant packaging, simplicity, and lightness are the hardest parts to design into the vehicle, and therefore take the most effort.

-David

[Michael Jones]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Packaging and seeing the whole picture, those are the most difficult aspects of design.
<HR></BLOCKQUOTE>

Just came back from the INCOSE annual conference on systems engineering, so I'm admittedly more biased than normal...but this comment is bang-on. In more than a few cases, from our student projects to space systems, the whole is both greater than the sum of the parts and is wholly dependent on the weakest link. One presentation made it quite clear that parts failure was rarely the issue - using the parts in conjuction with others inevitably was.

Cornell's systems approach really addresses packaging issues (three iterative design mockups) and more or less encourages big-picture thinking, at least in leadership (mostly through our faculty advisor, who stresses the issue, but also through people like myself who have an interest, and strong team leaders who implicitly understand the whole shebang whether they're aware of it or not...)

Also important is to consider is the nature of the competition and what is needed to win it. When one looks at this, suspension issues do rise to the fore. It is a suspension-oriented event, at least dynamically. Static events, being 35% of the total, are also quite important - ignoring cost, presentation and design is done at your own peril. Peak power - the thing that drives many engine folk - come quite a way down the list of things to worry about. Not sure what the other top 10 folk hit in their dyno tests, but I'd bet it's within a very small range (75hp+?) and easily compensated by effective suspnesion design and implementation.

---
Cornell Racing
http://fsae.mae.cornell.edu

[Colin]

Our team is very much still in the mind set of "simple light and reliable" Due to being very heavily involed in manufacuting I belive that one of the best ways of reducing the weight of the car is a to design as many parts of the car as possible before the chassie is consided, thereby decreasing the need for large heavy brakets to mount components. I understand that the need for stiffness in the chassie is a major design consideration It's just that i have seen time and time again a car that should have been light and well packaged increase substantially in weight due to after thoughts of mounting components. The amount of times i've gone to add a component and said to my self "if only that bar was 3mm closer or if only that bolt was 1 mm smaller this would have been such a neat job". I guess evrything is simple in heinsight though.

Full Boar Racing

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Not sure what the other top 10 folk hit in their dyno tests, but I'd bet it's within a very small range (75hp+?) <HR></BLOCKQUOTE>
Hmm, I'd take that bet. http://fsae.com/groupee_common/emoticons/icon_wink.gif

I couldn't agree more with everything else you've said though, the product as a whole is the most important thing, and communication between sections and integration of them is the most difficult task.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[This message was edited by Charlie on July 04, 2003 at 05:36 PM.]

[Frank]

charlie,

what do you think the top 10 DO get in HP on the rollers at the comp?

regards,

Frank

[Charlie]

Oh, I have no idea. I just know what we got on our own dynojet before compettiion, and it's considerably less than the top horsepower winner at competition. We did not run on the Detroit dynojet.

Our peak power number was not something we worried about, we were a lot more concerned with drivability and shape of the curve. (I'm not implying teams with a higher peak than us had worse curves or drivability, I think we have more work to do). But I think my competition experience would agree that horsepower peak is not extremely critical, drivability is. As long as you are tire limited you can always put as much power down as the next guy on the courses we see.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Angry Joe]

Designing a skidplate that didn't peel off the car the first time someone chucked the car around our crater of a parking lot was quite a challenge.

Seriously, although I took no part in it I think the drivetrain guys have the hardest design job. Tough packaging, tight tolerances, lots to think about and narrow margains for factors of safety make it less than a picnic.

Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)