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Thread: Reasoning your way through the FSAE design process

  1. #31
    Just saw this Geoff. Well done.

    I have been practically begging every team I've judged in design to incorporate a lapsim program. Even basics can be valuable, as you've proven. Unfortunately I've never had a chance to have a team like this in any competitions I've judged.
    -Charlie Ping

    Auburn FSAE Alum 00-04

  2. #32
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    Hi gents,

    Thanks for the kind words. I'm afraid I've had a few too many work commitments and not enough time to commit to further writing, but I'm sure that is the same for most of us. I've only managed a few minutes today as I've just got home from the dentist - so apologies if I'm slurring my words...

    Scott, to be honest mate, I just don't know. I sometimes (often?) doubt that you can really "teach" good management practice, as the best teacher seems to be experience. FSAE is designed to be a brilliant experience, and with appropriate reflection you can take away a lot of good info that is invaluable for your professional career. But not many come in with that experience, and it is up to the individual as to how quickly they can work through the experience / reflect / learn process.

    Some unis tend to attract students with a lot of practical experience, and RMIT has certainly benefited greatly from this over the years. Sometimes it backfires, for example when team members with racing backgrounds barge in and force pro-team motorsport "wisdom" on what is in many ways a non-motorsport project. (This often reveals itself as blown budgets, expensive componentry, some highly refined vehicle details but an unfinished car overall)

    Anyway, I see three key aspects of knowledge transfer.

    The first part of good knowledge transfer is the material itself, and in this case design and event reviews, prepared CD's for new team members (welcoming docs, team history / philosophy, etc), shared network drives, etc can be really helpful. Scott, the Monash initiation CD I saw in 2005 was brilliant.

    The second part is the human "teaching" side of it - how the existing team attempts to share the info with the incoming team. This is where mentoring, theory / philosophy seminars, and especially social events come into it. Getting alumni and senior team members to mix with the newbies can be gold as far as initiating them into the team's philosophies. The best teams I've seen are usually the more social ones, and have approachable and encouraging seniors and team management.

    The final aspect is the learner themself, and this is where we have least control. Some want to learn, some think they already know it all, some just want the outgoing crew to hurry up and ssip off so they can get on with doing their own thing. It's a culture thing, you can do your best to engender a supportive learning environment, but there will always be those who think they are above being helped.

    Dinner's ready so I've got to run, but just one point very quickly. Edward De Bono was on ABC radio recently, speaking about critical thinking. His point was that it is presently fashionable to think of critical analysis as finding fault. This leads to a culture of dissatisfaction and often change for the sake of it. Critical appreciation is a much rarer and finer talent. Something to keep in mind when your team is redesigning its pedal tray for the 10th time in 5 years...

    Cheers all,
    Geoff Pearson

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

    Design it. Build it. Break it.

  3. #33
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    Originally posted by Big Bird:
    Scott, to be honest mate, I just don't know. I sometimes (often?) doubt that you can really "teach" good management practice, as the best teacher seems to be experience. FSAE is designed to be a brilliant experience, and with appropriate reflection you can take away a lot of good info that is invaluable for your professional career. But not many come in with that experience, and it is up to the individual as to how quickly they can work through the experience / reflect / learn process.
    I think one of the most under appreciated aspects of the FSAE/FS experience is project management practice that students get. I'd guess the majority of the participants in this forum are mechanical engineering students or alums. Most ME undergraduate programs just don't do a very good job teaching project management. Participation in FSAE/FS forces these students into project and organizational management roles, and they will almost universally learn from it.

    Geoff, I go back to your original post in this thread, and the discussion on Level 4. There is a tremendous opportunity within FSAE/FS to create/innovate at the project and organizational management levels. This is difficult to duplicate in industry, what CEO is going to let you completely redesign the organization or its processes? But in FSAE/FS you can try a new management process or organizational structure and see if it works better than the old one.

    One of the best things that happened to the OSU Formula team was when our Dean combined the Industrial and Mechanical Engineering Departments into a School. The IE's bring a background in process design, and we've put them to work on redesigning manufacturing processes, supply chain processes, upper level organizational design, and design of temporary organizations (think FSAE/FS competitions). The other best thing was when we started exchanging students with Ravensburg. The Global Formula Racing team is an example of innovation that is possible at the organizational level. Where else but FSAE/FS could university students design and run a global organization of this size and complexity? Experience/reflect/learn/redesign, and hopefully we can improve the organization whilst continuing to give the students an experience like no other outside FSAE/FS.
    Bob Paasch
    Faculty Advisor
    Global Formula Racing team/Oregon State SAE

  4. #34
    I'm not sure if this belongs here or in the thread currently running on objective engine selection. The ideas certainly link to Geoff's 4 level approach to the FSAE competition (note: not the design of an FSAE car).

    Looking back on our teams history you can extract some interesting bits of information which may provide insights into our lack of success. We have never designed a concept for our approach to the FSAE competition and we have never sat down and dissected the functional requirements of the FSAE competition. Our car designs have been a mixture of guesses, incremental developments and copy ‘catting’ other designs. There has been a reasonable amount of research go into subsystems but it has never been well integrated.

    We have often run out of money, time and people. Unfortunately when looking for reasons behind our lack of success, we have compared ourselves to other teams and then put it down to not having what they have (money, people, machine time etc). I think FSAE teams could really benefit from taking a very thorough look at their team including: university support (facilities, access to machinery, workshop space etc), team numbers (also looking at individual strengths and weaknesses), time and budget. Once this is well understood a team can start to work out a concept. This is where the old sporting catch cry of 'play your own game' really comes into play. Others have touched on it before and I really agree, the successful teams with carbon everything, titanium, interconnected suspension etc do a really good job of psyching out the opposition. When aspiring teams look around they see the successful teams with this sort of technology (generally acquired over several years at great effort) and immediately think they must also have it to be successful. By playing your own game you can work up a solution at this conceptual level that best fits YOUR teams' strengths and weaknesses.

    We have been building space frame, independent suspension, 4 cyl 600 cars since we started, with the exception of 2009 (the beginning of a new era). Conceptually I would say our cars have had 85-90% of the theoretical max performance of an FSAE car and through poor analysis of resources and constraints we have blown schedule and budget maybe extracted 75% of the 85-90%, so that leaves us with a performance of about 64-68%. Poor competition results and blown budgets quickly draw the attention of critics who very quickly and vocally start asking 'what's the value for money/resource with this project?'

    We are now moving to a new strategic concept where we will be aiming to design a car with maybe 75-80% of the theoretical maximum and extracting 99% of that potential. Straight away you can see that we will be ahead of our past experiences and we may find that by being thoroughly tested, we may have 75% of the theoretical potential, a reliable car, thorough entries to the static events, documentation of designs (so the future teams now why we decided to do this and not copy the worldwide top 5), maintenance and team admin procedures, well maintained sponsor relationships, semi decent grades and most importantly in my mind (as a postgrad student) a sustainable FSAE program for the benefit of students to come.

    I think I have some more to say on this area but I better let my thoughts ripen a little more.

    Cheers
    Olly

    Academy Racing 04-07, 09-11
    UNSW@ADFA

  5. #35
    Originally posted by oz_olly:
    ....We are now moving to a new strategic concept where we will be aiming to design a car with maybe 75-80% of the theoretical maximum and extracting 99% of that potential....
    This. So much this for us during this year.
    Northwestern Formula Racing

  6. #36
    Bump to get this back to the top of the discussion board.

    Just wanted to let BigBird know that his ideas have made it into endurance racing. I'm in a school at Le Mans, and we're building a car for the VdeV championship. The previous students have lacked a direction, which is reflected in the design of the car. After realizing that it sounded a lot like my last seven years of FSAE, I'm adapting the topic of this thread to a management manual for our team.

    Does anybody have any "success stories" they can share? Or even better, "failure stories"?
    Mississippi State Motorsports 2003-2010
    Everything but the kitchen sink

    ISMANS
    iMaster 2011
    Conception Auto Advancee par la Competition

  7. #37
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    Hi Matthew,

    Thank you, that is really flattering. Please keep us posted as to progress, sounds like a cool project. I've always thought endurance racing to be the ultimate goal for a motorsports engineer, it seems to have a lot more scope for ingenuity than the more controlled forms of motorsport.

    In regard to case studies, I slapped up a follow up piece about our (early) RMIT project back when I wrote the above, but never posted it. I'll give it a bit of a cleanup and post it in the next day or so.

    Cheers,

    Geoff
    Geoff Pearson

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

    Design it. Build it. Break it.

  8. #38
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    Hi all,

    I wrote the below quite some time ago as a follow-up to my original post, but then thought twice about posting it. On re-reading it, I don't think it really gives away any info that I haven't posted already on these forums at least once over the past few years. But for those of you who haven't experienced the full tedium of my earlier random postings, this will neatly condense them into one space - in total a sure cure for any FSAE-induced insomnia you may be suffering.

    Please forgive any perceived self-indulgence about the below. I don't believe we are particularly impressed with ourselves, but it does show how we used the design process explained above to our advantage.

    To give the relevant context to our choices and decisions, I will outline a little of our history first.

    RMIT History, circa 2003
    At the start of 2003 we were in a rather ordinary position. We had failed to complete either of the two previous years’ events, and there was talk around the uni of the project being cut back or even closed down due to abuse of privileges and huge money being wasted on a project that was giving no results. The engines we inherited from previous teams were pretty well stuffed, a couple of the team’s previous sponsors had dropped out, and when we finally got the go-ahead for the project our effective budget was about a quarter of what the previous team had spent. Also, Uni of Wollongong had proven to everyone here in Oz that they were just going to punish any team that wasn’t 100% ready for the event. We didn’t have anywhere near the money required to compete with UoW at their own game, and we were going to have to come up with something unique and cheap.

    A crew of us had attended the previous 2002 Oz event (where UoW and UWA had pretty well hosed everyone), and in my own notebook I had taken down the following:
    ? Of the 22 teams entered, only 4 were looking anywhere near competitive on track (UoW, RIT, UWA and Stralsund from memory)
    ? Of the 18 struggling teams, nearly all of them were having engine problems of one sort or the other (i.e. engine wasn’t operating at its full potential, if at all)
    ? Our own team tried to win the comp mainly by focussing on a gun engine (read turbo…), and were way off the pace before they eventually blew up
    ? The struggling teams were all showing similar signs of poor time management – incomplete cars, harried team members, poor pit management, etc.

    The overwhelming conclusion that we drew was that the majority of teams were attempting too much, and failing to get anywhere near completing the project. This opinion was shared by a number of motorsport industry people we spoke to at the event, who were despairing at how most teams were overcomplicating their designs and struggling to pull it all together.

    Given that many were struggling to get their engines sorted, the big question we asked was, exactly how important is the performance of the engine? If engine reliability is such an Achilles heel for most teams, why does every team seem to mess around with their engines so much? Could we find a simpler solution that would lessen risk of engine failure? If we decided to take a step back from excessive engine development, would it be possible to gain points in other areas?

    Setting Project Goals
    Starting with the above observations, we had to start setting some directions for our design. Very roughly, below is a representation of our train of thought.

    Level 4 goals / directives / constraints:
    * MUST complete every event at competition;
    * MUST complete project for under $(insert figure here);
    * Need to find project strategy that leaves enough time for static as well as dynamic events;
    * Need to have vehicle running by start of November at latest (December comp);
    * Need to develop strategy that minimizes impact on uni workshop resources;
    * Very important to source donated engine;
    * Very important to reduce student workload compared to previous years;
    * Very important to attract new sponsors;
    * Will be difficult to compete with UoW on equal terms, so need to develop comp strategy that attacks them from “left field”.

    Level 3 goals / directives / constraints:
    * Focus on points that other teams aren’t seriously chasing (fuel economy, static events);
    * Ensure competition completed by simplifying design (reducing number of parts, dump turbo);
    * Allocate appropriate people and resources to static events;
    * Reduce vehicle mass to aid fuel economy as well as track speed;
    * Focus on cornering over straight line performance (cornering acceleration being “x” times more effective in returning points than straight line acceleration);
    * Allow some deficit in engine performance due to low points sensitivity to straight line acceleration on FSAE tracks;
    * Majority of corners on typical FSAE track taken with very little or no braking so design suspension accordingly;
    * Vehicle must be rugged and easily serviceable at the event itself

    Level 2 goals / directives / constraints:
    * Overall vehicle mass target under 200kg,
    * Engine output at least 50hp max,
    * Steel space-frame chassis imposed (constrained by finances and team knowledge);
    * Targets were set for overall vehicle geometry such as wheelbase, track, trail, scrub radius, roll axis geometry, etc;
    * Design constraint of 10” wheels set for unsprung and suspension designers (for mass and rotational inertia reasons);
    * Design for torsen diff (already owned by team);
    * Suspension geometry to be biased approx 80% towards cornering over straight line acceleration, etc.

    Level 1 goals and directives
    * Component mass targets set to achieve sub-system and whole vehicle mass targets,
    * Timeline / budget / material constraints imposed on component designers, etc.

    The above goal-set is not exhaustive, but just representative of the types of reasoning that was being employed at each relevant level. Note that the Level 1 goals and objectives were the simplest of the lot – once you reason your way down from the top, develop your overall strategy and work it through to the individual components, individual component weight, material and budget constraints are pretty well defined. From there, we work back up the other side of the “V” to the event itself, and then final project wrap up, reporting to supporters & sponsors, handover and knowledge transfer etc.

    In our case we were looking for a simpler overall vehicle design that would reduce project completion times, and were questioning whether we could trade off some engine performance for gains elsewhere. We also had some knowledge that Yamaha were about to release an electric start 450cc single (the WR450), so we might be able to “hitch on” to some marketing hype and help promote a new bike for them.

    Variables of interest
    So to assess how the above might translate into competition performance, the major variables of interest to us were as follows:

    Acceleration (divided into forward, lateral and braking)
    Vehicle Mass
    Engine output
    Tyre grip
    Fuel economy

    Now simply treating each of the above in isolation of each other doesn’t give a true assessment, since there are a number of conflicting relations linking the above variables. For example, arguments I heard early in our project that “a 50hp car needs to be under 300lbs to match the power:weight ratio of a 600/4” were a bit simplistic – power:weight comes into play only on straights, a lesser weight can help you elsewhere around the track too. Understanding the links between the above parameters was vital.

    The most relevant relationships to my argument are listed below, although there are of course many more:

    1. Lateral acceleration tends to increase with reduction of mass (through tyre load sensitivity),
    2. Forward acceleration tends to increase with increased engine output, and with reduced mass
    3. Vehicle mass would tend to increase with increased engine output (due to stronger/heavier components required in drivetrain, and in the case of different engines concepts, the mass of the engine itself)
    4. Fuel economy would tend to increase with increasing forward acceleration and velocity (due to higher kinetic energy change along straights and higher wind drag effects)

    So the main design conflicts we had to reason our way around were as follows:
    • More engine performance will give us better forward acceleration, but will tend to drive up mass. Through tyre load sensitivity this increased mass will tend to make us slower in corners. On the flipside, if we settled for reduced engine output, we could reduce weight considerably and get an amount of return in cornering performance
    • Greater forward acceleration will tend to result in greater energy demand (due to greater change in kinetic energy between corner exit and peak speed, and greater wind drag at higher speeds). Considering fuel consumption to be an energy load multiplied by the thermal efficiency of the engine, this indicates that the increased energy demand will drive up fuel consumption
    • Reduced mass would tend to win all round, in that it would aid acceleration in every sense and reduce energy demand – but practically there would be lower limits to this before component stiffness and durability would be compromised

    It was clear that to gain a full understanding of the competition, we had to determine sensitivity of point-scoring for each of our variables of interest. This would require a track map of some sorts (we had access to a dimensioned 2001 Oz Autocross / endurance track map, but it wouldn’t be too hard to come up with one of your own), some good estimates of power and mass, and eventually when we got the tyre data we were able to calculate the load sensitivity of the tyres and see how mass would affect cornering.

    Analysis process
    The process, starting with the most rudimentary analysis and moving upwards in complexity, was as follows:

    Stage 1:
    Simple visual scan of the track indicated 220 metres of straights and around 350 metres of corners (from memory!). There were 14 corners, of which only 4 had a straight before them and could be considered to require braking (therefore 10 corners being entered with no pitching of the vehicle). A rough estimate that about 25-30% of each straight was under brakes, gave a rough idea of the amount of time spent on full throttle. Very basic analysis, didn’t give any point sensitivity but at least gave some rudimentary info for suspension design goals

    Stage 2
    Given we were mostly interested in engine performance, the next step was to get some idea of how power affected lap times. The details of this rough analysis are outlined in a thread I wrote a few years ago called “Life, the Universe, ….etc” (look it up if you want). Basically, using simple constant acceleration equations we learnt in first year dynamics (v = u + at, x = ut + 0.5at^2), we started with an initial corner exit velocity, an assumed acceleration, and then experimented with how much time we saved over a straight if we increased & decreased acceleration by a few percent. These rough hand calcs gave us a point of reference, whereby we discovered an effective 20% increase in power might only return us a 1-2% decrease in lap times. More useful info than in our first “analysis”, but still a bit rough

    Stage 3
    To get a realistic comparison between all of the variables you really need to start looking at a more comprehensive lapsim. Now you can go to all the trouble of learning a complex program like ADAMS and do it that way, but being a bit of a simpleton I went and did it all in Excel (I like being able to see all the numbers and check that they are reasonable as I work – and I could also reduce the lapsim to only the variables I was interested in). So starting with the 2001 trackmap, we broke it up into 1 metre increments and set about writing the world’s dumbest lapsim:
    • Assume constant lateral accel circular arcs through corners, car following centreline of track (this defines corner entry and exit speed). Lat Accel value defined by tyre grip limit.
    • Constant decel braking to the corner entry speed, defined by tyre grip limit
    • Forward acceleration calculated as a function of corner exit speed, mass, power (see Gillespie or any decent vehicle dynamics books for formulae)
    • Other programming tricks that you may like to work out for yourself to calculate fuel usage, whether vehicle is grip or performance limited at each point on the track
    • Etc...

    The spreadsheet was written so that the following variables could be user defined:
    • Overall Mass
    • Vehicle average power
    • Tyre coefficients of friction in lateral, longitudinal and braking orientations (at a given normal load)
    • Tyre load sensitivity (derived from TTC data)
    • Vehicle frontal area, Cd, average rolling resistance, predicted engine thermal efficiency

    The lapsim was then duplicated, so we could calculate values for two different vehicles. Final times for autocross, endurance, accel event and skid pad were then converted to points (using formulae in rules, and assuming the faster car “won” the event for min time values), and voila – we could get a rough idea of relative points for different concepts.

    To be honest, the final sensitivity analysis took about two good days to program, including food breaks, the odd beer and the intermittent distraction reading dirt bike mags and the like. It wasn’t that hard. By simplifying the path taken to simple series of straight lines and circular arcs, we reduced lap sim programming from a year long project to something that a first year dynamics student should be able to complete. By doing so, we learnt a heap about where points are gained are lost in this comp, and developed some really useful rules of thumb to help manage and prioritize the design process. Such rules of thumb included:
    • A 1% increase in cornering acceleration would give “x” times more points return than a 1% increase in engine acceleration
    • A 1% increase in cornering acceleration would give “y” times more points return than a 1% increase in braking deceleration
    • A reduction of mass of 1kg would be worth approximately “z” points across the whole competition
    • A 1% increase in engine power would gain around “a” points in lap time, but would also result in around “b” points in fuel economy
    • Etc
    I was satisfied that the analysis was reasonably correct – despite the simplifying assumptions it was still predicting around 15% full throttle time (depending on vehicle concept), max speeds around 110kmh, lap speeds close enough to times recorded around that track. As a means of refining shock settings or other detail refinements it would be too far off – but at the conceptual level it was cheap, quick, simple, easy to use and gave lots of easily accessible and useful info to drive the project.

    In our particular case, we learnt that while we were going to lose points from straight line performance by going to the smaller 450cc engine, we were going to make up for some of those points in both cornering performance and fuel economy, (and maybe a few more for cost report and “manufacturability” if we argued the point well right). We were able to quantify this in terms of points, not just argue clumsily in terms of kilos and kW. To be honest, the calcs indicated that in terms of outright potential the 450 single would be around 10-15 points short of a good 600 4cyl, if both were presented perfectly (under the old 50 point fuel economy rules). However given our own team circumstances we knew we would come much closer to fully race prepping the simpler single design than a 600 four, and hedged our bets there.

    That first 450 single car was built rather heavy (around 195-200kg), and wasn't that powerful (around 50hp). But it was finished in time, well tested, and as such was our first car to win an event outright.

    I'll make sure my next post doesn't seem so self obsessed, but I hope the above might at least help a few of the newer teams

    Cheers,

    Geoff
    Geoff Pearson

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

    Design it. Build it. Break it.

  9. #39
    Very good stuff, Geoff. Thanks for sharing.

    One of the biggest takeaways IMO is the value of starting SIMPLE in simulations and predictions and working up in complexity - rather than jumping into a package like ADAMS.

    It's amazing how much can be cobbled together in a few days or a week's time, and how much value it gives for up front design.

  10. #40
    thanks again Geoff, again, a wealth of information in one easily accessible place.

    PLEASE PLEASE PLEASE mods get this stickied!!!!

    Ed
    University of Glasgow BEng 2003-2007
    Oxford Brookes MSc 2007-2008
    University of Glasgow PhD 2009 - god knows when.....
    WORK ....
    --------------------------------------------
    Preliminary operational tests proved inconclusive.... It blew up when we flipped the switch

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