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Thread: Reasoning your way through the FSAE design process

  1. #121
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    Geoff,

    Excellent job that you are doing here! And it is really good to see so much positive support.

    As you know, my usual policy is that if I have nothing critical to say, then I say nothing at all . However, this subject is too important to ignore. So, hoping I don't ruin all your good work...

    The difficult part of this subject is "How to get the message INTO their heads?". During my brief career coaching junior footy (Rugby League) I decided that the best way is via a short list of easy to remember sayings or "Rules". These are relentlessly drummed into the kids' heads during training, along with the million little details of how to execute them. Then on game day it is just a matter of shouting "RULE N ...!" from the sideline, at the right time.

    So, without further ado, Supervisors and Team Leaders are invited to select a short list from the following, or add their own.

    ~~~~~o0o~~~~~


    Adages, Aphorisms, Maxims, Mottos, Principles, Proverbs, or just Good Old Sayings...
    ================================================== ==================================


    From Z's "Seven Rules for winning Footy Games".
    -----------------------------------------------

    Rule 1. Football is a simple game, keep it simple!
    The most shouted rule! Even when playing games, kids want to complicate things!!!

    Rule 2. Good teams beat great individuals. Support, Support, support!
    Everyone pull in the same direction.

    (Rules 3, 4 & 5 are footy related.)

    Rule 6. Never, ever, ever, let the opposition pull your pants down.
    Stay awake. Corollary: If the opposition are asleep (and in FSAE, most are ), then pants them!

    Rule 7. Winning begins on Monday. Practise, practise, practise!
    Applies all year, but don't turn up raceday with a never driven car.



    Geoff's Level 4 Stuff.
    ----------------------

    * War ... is the ground of death and life ... so it is imperative to examine it carefully.
    Sun Tzu, "The Art of War". Fortunately FSAE is a game. If it was war the cars would be much faster.

    * To make a small fortune in FSAE, start with a large one.
    Be nice to your sponsors.

    * If you keep doing what you've always done, you'll keep getting what you've always got.
    Don't polish a turd.

    * You can't cross a chasm by taking small steps.
    Yep, sometimes you have to take that big leap.

    * To make an omelette, you have to break eggs.
    Someone is going to be unhappy.

    * Don't throw the baby out with the bathwater.
    You took the big leap last year but it didn't work. Don't go back to polishing turds...

    On the other hand...

    * If it ain't broke, don't fix it.

    But don't forget,

    * Tempus fugit.
    "Time flies". And the closer to comp, the faster it flies!

    And above all,

    * KNOW THYSELF.
    This chiselled into the wall of the Temple at Delphi. Also from Benjamin Franklin "There are three things extremely hard - steel, diamond, and to know one's self". Or Clint Eastwood, "Magnum Force" - "A man's got to know his limitations". Or Anon "Don't bite off more than you can chew". So don't start what you can't finish.



    Level 3.
    --------

    * Things are numbers.
    Pythagoras. FSAE cars are just a list of numbers. Choose wisely.

    * Let no one ignorant of geometry enter here.
    Above the entrance to Plato's Academy.

    * There is no royal road to geometry.
    Euclid to the Pharaoh Ptolemy. So practise, practise, practise!

    * More is in vain when less will serve.
    Isaac Newton, "Principia". Followed by "For Nature is pleased with simplicity, and affects not the pomp of superfluous causes."

    * There are lies, damn lies, and STATISTICS!
    Just kidding Kev (err..., not).

    * Don't argue with a fool. First they drag you down to their level, then they beat you with experience.
    Ah, those first "concept" meetings...



    Level 2.
    --------

    * To finish first, first you must finish.
    That means NOTHING can break in Endurance!!!

    To build a fast car, through the ages;

    * 1900 - Put a big engine in a small chassis.

    * 1950 - Simplificate, and add more lightness.

    * 2000 - Aero above all!
    Hmmm, engine size restricted, so think about the other two...

    * A wheel at each corner.
    Maximum yaw control, minimum yaw resistance.



    Level 1.
    --------

    * Measure twice, cut once.
    Huh??? ... Oh!!!

    * Whatever can go wrong, will go wrong.
    Murphy!!!

    * The devil is in the details.
    And he's a cruel, sadistic bastard, who'll rip your hearts out one lap from the end of Endurance!

    ~~~~~o0o~~~~~


    And then, when it's all over, ... maybe???

    * Vini, vidi, vici!
    Julius Caesar - British tour (FSUK yr?), "I came, I saw, I conquered!"

    And finally (for now...)

    * My words are very easy to understand ... yet no one understands them.
    Lao Tzu, "Tao Te Ching". Well, hopefully some do...

    Z

  2. #122
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    * A wheel at each corner.
    Maximum yaw control, minimum yaw resistance.
    What is your definition of yaw resistance? In our terminology, a wheel at each corner (ie, longer wheelbase) increases yaw damping, relative to the same car with shorter wheelbase. Simple case discussed in RCVD p202-4.

  3. #123
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    Doug,

    I was referring to "yaw inertia". That is, the car's mass distribution that resists yaw acceleration. So minimum "Iz" in Tz = d(Iz.Wz)/dt.

    "Maximum yaw control" is a case of maximising yaw couple "Tz". This is done by maximising "R" in Tz=Sum(FhxR), where the Fh's are the horizontal ground-to-wheelprint forces, and the R's are the distances from CG to wheelprints. Note that the Fh's can be lateral (eg. from the steering wheel), or longitudinal (eg. from "fiddle brakes").

    "Yaw damping", IMO, is a form of yaw control, since it resists yaw motion. The usual arrangement is to use the steering (hand) wheel and the front wheels to destabilise the car in order to change its yaw motion (turn in to a corner). The rear wheels are kept in the straight-ahead position to maintain some stability, via a "yaw damping" type mechanism. If we want lightning quick turn in, then we slightly steer the rear wheels out of the turn.

    So in simple terms: Wheelprints as far from the CG as possible. All major masses as near to the CG as possible (but the wheels have mass, so make them small). Apply destabilising control to the front wheels (lat. and long.), and use the rear wheels as a stabilising rudder.

    Z

  4. #124
    Wheelprints as far from the CG as possible
    Doesn't that put the wheels closer to the bright orange cones?
    Buckingham

  5. #125
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    Buckingham, how about "Wheelprints as far from the CG as is practical."

    (Putting mental images into words is hard... )

    This issue more fully covered under "Objectively Choosing an Engine".

    Z

  6. #126
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    Been wanting to post a reply to one of Geoff's much earlier posts for quite a while now. It is really regarding designing for the long run, and it will basically tell the story of the first 4 cars of UWA.

    Geoff had made the claim that you couldn't optimise from Roast Beef to something completely different, the intermediate steps would taste horrible. I disagree. The first 4 cars for UWA went the following direction (I will try to keep to the Masterchef analogy which I loved):

    2001: Roast Beef. We realised our biggest problem was not whether Scallops or Chocolate cake would have been better. Rather the problem was we didn't even know how to use an oven. We spent the year trying to figure out all of the complicated steps and instruments required to cook, as well as figuring out who was going to pay for the ingredients. When it came time to make a meal we figured that it was unlikely that anyone would eat at our restaurant so we just practiced by following the recipe for roast beef.

    2002: Surf and Turf. This is where Geoff's post assumed all intermediate steps would be horrible, he had forgotten the Australian pub meal of Surf and Turf (Steak and Prawns). We were much more confident cooking now and still liked the flavour of beef. However we were becoming fairly sure that we preferred seafood, we were convinced that after years of eating roast beef the customers would too. Not having tried making it before we decided to just try to cook a few prawns, if they didn't work out we still had the steak.

    2003: Prawn Linguini. Short story really. We found out that it was easier for us to make the prawns than the steak. They cooked faster and we had better access to the stovetop. Dish looked great, prawns were a little stringy.

    2004: Scallops. After 4 years of being a trainee chef we decided to serve up some scallops. We now had plenty of cooking experience all headed towards this end goal. They tasted fantastic.

    It was a great four years of cooking with a few familiar faces, got to learn a lot in the process. I heard sometime after I left that they hired a french chef. Went on to win a few cooking awards with his updated scallops recipes. Some critics have complained that the dish sometimes has too many complex flavours, others are worried that the customers are almost as sick of scallops as they were of roast beef.


    For the FSAE version:

    2001: Attempt at a Cornell spaceframe clone
    2002: Updated spaceframe with all the design tidier and a few structural composite parts
    2003: First composite car, much more rear weight bias, shorter car. Started serious damper testing
    2004: First Kinetics car.


    The plan was to win the US comp within 4 years (we ended up coming second). We were sure that we had to do something different. This was the time when no one could build a better 'standard' car than Cornell. We spent a long time developing manufacturing and design techniques and operated under the banner of reliability first, lightweight second. We also spent a lot of time getting and maintaining sponsors.

    I think that for any sustained success in this competition teams need to develop a long view of the competition, and begin developing the skills in house. Successful cars magically seem to appear at the end of long development plans, rather than from isolated flashes of brilliance.

    Kev

  7. #127
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    Kev - bloody brilliant. I stand fully corrected. Or at least I will stand corrected, at the moment I'm still doubled over laughing.

    How could I forget Surf and Turf? Shame on me, I feel as though I should hand in my Aus citizenship.

    Ok Kev, now for your next big challenge. Lets see ECU optimize their way from Surf and Turf to chocolate cake

    Cheers!
    Geoff Pearson

    RMIT FSAE 02-04
    Monash FSAE 05
    RMIT FSAE 06-07

    Design it. Build it. Break it.

  8. #128
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    Geoff,

    I love the cooking analogy. Cooking is very much like engineering, there is a lot of science to it, but it takes wisdom to mix the right ingredients in the right way.

    Recently my wife and I were treated (no way we could afford it ourselves) to a french degustation menu by the best french chef in Perth. It was 8 courses with 6 accompanied glasses of wine. The analogy to the year by year nature of the team was striking. Each course was different but borrowed ingredients from the previous course. The set wine menu also complemented the meal like a team complements its car and vice versa. And just like FSAE we were left feeling full and not ready to see another meal for a while.

    I feel that it is important to carry as much over from one car to the next that does not detract from your developing concept. This may be a case of carrying over well developed processes rather than actual parts. Also just like a restaurant the worst thing you can do is serve an inedible meal. The consequences of one year in which you fail to run can be felt for quite a while afterwards.

    ECU at the moment is more of a prawn linguine than a surf and turf. So to go from prawn linguine to chocolate cake:

    Prawn Linguine: Car as is, Honda CBR Composite chassis

    Prawn Souffle: Keep all the parts similar and do an engine swap to a simple reliable single cylinder car. Spend the year adjusting to the new drivetrain. The honda would still be a last minute backup.

    Chocolate Souffle: Keep the same processes, but now all parts on the car are designed to account for the lower loads associated with the lighter car.

    Chocolate cake: Simplify systems drastically. This may be heading down the road of Z's brown go kart.


    At each step you can have a well tested and developed car that is not a rapid departure from the last, but end up with something very different. I would expect that 2-3 years would be the time allocated to move from what ECU has to the successful RMIT model from the past. I am aware that some may see that sort of timescale as conservative.

    The way I see the planning process is that you are always heading in a direction of change, sometimes planned, sometimes not. I prefer to go there at a pace that allows you to fully develop and test the ideas. I have seen far too many teams with really very good ideas fall over due to poor implementation. Looking at the points differences between the top teams comps they are too large to be attributed to the differences in concepts.

    Kev

  9. #129
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    I'm hesitant to respond too quickly as it brings my name back to the thread header and it looks like nothing is happening here. Kev, if you are still online maybe you could just throw down one word as a response to this and restore your name to the top.

    All I want to say is that even though a 2-3 year development plan might sound conservative to some, given the high failure rates even a conservative first car can score well - outright podium even. As long as the car is reliable, it is a contender. Getting into the top 10% is just so damn easy - if you let yourself believe it.
    Geoff Pearson

    RMIT FSAE 02-04
    Monash FSAE 05
    RMIT FSAE 06-07

    Design it. Build it. Break it.

  10. #130
    Bump
    The trick is ... There is no trick!

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