We'll wrap up the series on setup sheets with some specific thoughts about parts of the sheet's content. For the most part, you can refer to the basic sports prototype sheet from Part 1, reproduced below.
Sports Car Prototype Setup PDF
Tolerances
You and the crew need a mutual understanding of the tolerances for any given adjustment. There are two pieces to this. The first is your knowledge, as engineer, of what constitutes a significant change in any adjustment. The tolerance, of course, should be tight enough to avoid changing the car by missing the target. The second is the crew's ability to hit your target and your tolerances, either because of finite steps for some adjustments, or because of inability to either measure or adjust tighter than some tolerance. For example, if you call out a toe-out setting to a tolerance of .002", you are way tighter than adjustment repeatability, measurement accuracy, and large enough difference to effect the car.
Specific hardware
When you know it, call out the specific part number, hole number, shim thickness, or other part or adjustment specification that should lead to a specific setup target. The setup sheet above, for instance, is for a car with front camber slugs, rear camber shims, caster shims, and specific holes for wing adjustment. In each case, both the setup target and the hardware spec are called out on the sheet. In the event that the crew can't hit the setup target by following the hardware spec, something is either wrong or misunderstood, and discussion will be required.
Standard setup conditions
For the sake of repeatability and comparison, it helps to always set up with the certain setup conditions always the same. Tire pressures, driver weight, and fuel load are chief among these. If you're not using "setup wheels", the devoted metal fixtures that replace wheels and tires, then you should always use the same set of actual tires and wheels. Actual running conditions for the start of the session will vary. For instance, we'll set up at typical hot tire pressure, but start the session lower than that. Starting fuel load may be more or less than setup. You get the idea.
Actual vs. target
Some fields on the sheet may have spaces for actual vs. target. This is helpful if you want to record what you intended vs. how the car actually ran. The difference could be from tolerances, measurement precision, or simply error.
Corner weights
If you have a good grasp of the total weight and the percentages for front and left side, you should be able to predict the actual corner weights for any given cross weight within a couple of pounds. I tell my crew that, if they miss the target corner weights by more than a certain margin, they should contact me so we can figure out what's up.
Wings
Lots of folks call out wing angle as relative to the reference plane of the car, which is usually defined as some part of the underfloor. This seems simple enough. Time and again, though, it seems that zeroing the Smart Level against the floor isn't a totally repeatable process. I've come to call out wing angles as absolute, versus the ground. The results, for me, are more repeatable.
I learned this the hard way, in my early days in IRL. We had a flawed zero against the top of the tub floor inside the car. For part of the weekend, we struggled with lack of grip as we ran less wing angle than the series actually would have permitted us to use.
That about does it for setup sheets. Hope you've enjoyed it.
Friday, February 5, 2010
Monday, January 4, 2010
Setup sheets, Part 3
We now veer from the content of setup sheets to focus instead on using them. Since the setup sheet is primarily a communication tool, that will be the theme of this post. The final post will cover specific content items on the sheet.
What happens on the first usage of a new setup sheet?
Some teams want you, as a newly-arrived engineer, to use their existing setup sheet. OK, then get on with it. If you need to make changes to the sheet, phase them in as needed, with agreement of all concerned. No surprises allowed.
Other teams will allow you to use your own format. Or, maybe, you've decided to rework the existing format. In either case, it's absolutely essential to sit down with the crew and review the format and content of the setup sheet. The compressed layout needed to convey so much information will almost certainly lead to misunderstandings if you bypass this step. Remember, communicate!
When does the setup sheet need to be done?
Let's talk about the pre-event sheet first. You could wait until a day or two before the car goes on the setup pad. You'll probably only get one or two opportunities to do that, though, before someone gives strong verbal feedback, or worse.
On the engineering side, we often want to review notes and data from the previous event before deciding how to set up for the next event. Maybe we've got wind tunnel or 7-post testing coming soon, too. Maybe some significant analysis or simulation work will reach conclusions soon. All this work could have a significant effect on the setup, and not just on adjustments. We may need to make (and test-fit) aero or chassis parts, revalve shocks, buy parts, and more.
Meanwhile, the team typically has a limited amount of time to turn the car around. There will be a finite amount of manpower available to deal with changes. And, all this will usually happen on a schedule without much wiggle room.
What happens on the first usage of a new setup sheet?
Some teams want you, as a newly-arrived engineer, to use their existing setup sheet. OK, then get on with it. If you need to make changes to the sheet, phase them in as needed, with agreement of all concerned. No surprises allowed.
Other teams will allow you to use your own format. Or, maybe, you've decided to rework the existing format. In either case, it's absolutely essential to sit down with the crew and review the format and content of the setup sheet. The compressed layout needed to convey so much information will almost certainly lead to misunderstandings if you bypass this step. Remember, communicate!
When does the setup sheet need to be done?
Let's talk about the pre-event sheet first. You could wait until a day or two before the car goes on the setup pad. You'll probably only get one or two opportunities to do that, though, before someone gives strong verbal feedback, or worse.
On the engineering side, we often want to review notes and data from the previous event before deciding how to set up for the next event. Maybe we've got wind tunnel or 7-post testing coming soon, too. Maybe some significant analysis or simulation work will reach conclusions soon. All this work could have a significant effect on the setup, and not just on adjustments. We may need to make (and test-fit) aero or chassis parts, revalve shocks, buy parts, and more.
Meanwhile, the team typically has a limited amount of time to turn the car around. There will be a finite amount of manpower available to deal with changes. And, all this will usually happen on a schedule without much wiggle room.
It isn't really possible to say exactly how long ahead of the next event you need to be done. The correct answer is "it depends".
- Are you taking the same car to the next race as the previous one?
- How time-consuming are the changes envisioned, beyond simple parts swapping and adjustments?
- When does the car need to go in the trailer? How far ahead of that must the car be set up?
- How important are the non-adjustment changes, in terms of performance potential? How sure are you of their value, and how sure is the crew of their ability to complete them?
- How "non-routine" will the setup pad work be?
I can't, repeat cannot, overemphasize the importance of communication with the crew. If you envision changes, then you absolutely must discuss them well in advance of actually asking for them. Jointly review their probability of actually happening, the work required to accomplish them, when you can realistically have them defined, and what the possible pitfalls might be. Then, jointly decide on a plan.
A few thoughts:
- The optimal time for the setup sheet to arrive is just before reassembly of the car begins, and with enough lead time for all the changes.
- It may help to produce a preliminary setup, to be revised as engineering work finishes. Be advised, this approach is full of pitfalls and requires a clear understanding from everyone involved.
- When the races are coming hot and heavy, maybe on back-to-back weekends, you're likely to have to prepare setups for several races ahead of yourself.
Here's a clue - when the crew is consistently asking you for a setup, then either you are too late producing them, or they want them too far in advance. Talk with each other, figure out the situation, and fix it.
How to deliver the setup sheet?
I prefer to add a "cover memo" to draw attention to anything important. Maybe you're changing something that has remained constant for a long time. Maybe there are exercises to be done on the setup pad, or some specific instructions on how to do part of the setup. It's easy to have this discussion verbally, but there's always some risk of misunderstanding.
Now, what about between sessions at the track?
The basic situation between sessions is much like the pre-event setup, only compressed in time. As an engineer, you want to debrief the driver, look at some data from the car, punch some numbers into the calculator or software, and maybe crank out a sim run or two. The crew wants to get the car ready for the next session. Here's how you do it:
On the way back to the paddock or the garage, tell the crew chief whether you need a setdown. If not, then he can start on the maintenance issues while you work on the setup. Tell him what changes you're considering, if it entails a significant job (for instance, changing brake master cylinders can be a challenge on some cars), and agree on whether the change needs to happen now or can wait until the end of the day. Changing ratios in the gearbox, for instance, typically needs some lead time - you know you're going to do it, even if you don't know what ratios to install yet. Finally, agree on when he needs your final answer on the changes you just discussed.
Spend the rest of the walk back deciding if you can call out the setup changes NOW. If you can, you are now officially a hero.
Put out a job list for the crew, DAG, shock guy, etc. immediately after arriving at the paddock or garage. No ifs, ands, or buts.
Get into your job deciding on the setup changes with energy and focus. Debrief, analyze, and decide. Now. Take it as a personal challenge to avoid agonizing over decisions. This is going to sound brutal, but if you repeatly have to agonize over the setup, then you either aren't ready for the job or you aren't decisive. Either that, or there's something you haven't learned about the car and desperately need to figure out.
If you spend two hours fussing over the setup, with the crew waiting on you and the next session looming, only to decide on a big change like tearing into the gearbox (stressing the crew) or a trivial one like a minor spring change (insulting the crew), you are not a hero, and will not be able to repeat this behavior forever - unless you and the driver win a lot of races!
Once you've decided, communicate your setup changes clearly and concisely. I found out, the hard way, that a new full setup sheet IS NOT the way to do this between sessions. There is too much information on it for the crew to pick through, while searching for the changes. I simply provide a list of the changes. Sometimes the setup worksheet from the previous post in this series is a good way to do this, sometimes it goes on the job list. It's best to discuss it with the crew chief, no matter what format you use. Avoiding misunderstandings is the goal.
That's about it for today.
Wednesday, December 30, 2009
DOE in NASCAR Sprint Cup
Brandon Thomas is Chief Design and Development Engineer for Red Bull Racing in NASCAR. He has the dubious distinction of being the first victim to be drafted for a guest blog on The Race Engineer. Thanks a bunch, Brandon. Without further ado...
I feel honored to be invited to guest blog on The Race Engineer blog. I made the mistake of updating my LinkedIn profile with some obscure details of my work history and Buddy came calling. He and I have traded EMails over the last few weeks, and some of that content he felt was worthy of the blog. So, here goes.
DOE, design of experiment, was a topic briefly glossed over in my required statistics and probability class during engineering school. Had it been more of a focal point in the class, I probably would have paid much more attention. Seems the biggest problem educators have is making the course content relevant to the audience. I cannot explain the intricacies, or even the theory, behind the method in a simplified discussion. The point of DOE is to build a response model based on several user-decided factors. Like all models, it requires the user to be pretty informed ahead of time of what is expected in the results, but also to be somewhat open-minded when the results diverge from the expected. I’ll leave it up to you readers to do more research on the www on the method and its origins.
DOE was certainly revered in the pharmaceutical industry – probably still is. Types of experiments, the number of factors involved, and the complexity of the experiment are all parts of drug trials in this era. What does that have to do with making your racecar go faster around a given lap than the competition? Working smarter, not harder, eliminating the surrounding static, and concentrating on the most important setup parameters to achieve a result.
In this realm, I am alluding to a method of DOE involving simulation code. There are many basic advantages to DOE in the virtual world. The repeats can all be skipped, the number of factors can be rather large, and you can accomplish a full factorial design with today’s larger multi-core machines. There are other methods of DOE outside the virtual world, but I’ll take the academic copout that those are beyond the scope of this blog, and are sensitive information in a competitive environment.
Now let’s get to the good stuff. What does DOE methodology do for the race engineer?
One of the most useful tools to a race engineer when away from the computer is a Pareto chart based on the results of the DOE. Here’s an entirely fake example of one.
I feel honored to be invited to guest blog on The Race Engineer blog. I made the mistake of updating my LinkedIn profile with some obscure details of my work history and Buddy came calling. He and I have traded EMails over the last few weeks, and some of that content he felt was worthy of the blog. So, here goes.
DOE, design of experiment, was a topic briefly glossed over in my required statistics and probability class during engineering school. Had it been more of a focal point in the class, I probably would have paid much more attention. Seems the biggest problem educators have is making the course content relevant to the audience. I cannot explain the intricacies, or even the theory, behind the method in a simplified discussion. The point of DOE is to build a response model based on several user-decided factors. Like all models, it requires the user to be pretty informed ahead of time of what is expected in the results, but also to be somewhat open-minded when the results diverge from the expected. I’ll leave it up to you readers to do more research on the www on the method and its origins.
DOE was certainly revered in the pharmaceutical industry – probably still is. Types of experiments, the number of factors involved, and the complexity of the experiment are all parts of drug trials in this era. What does that have to do with making your racecar go faster around a given lap than the competition? Working smarter, not harder, eliminating the surrounding static, and concentrating on the most important setup parameters to achieve a result.
In this realm, I am alluding to a method of DOE involving simulation code. There are many basic advantages to DOE in the virtual world. The repeats can all be skipped, the number of factors can be rather large, and you can accomplish a full factorial design with today’s larger multi-core machines. There are other methods of DOE outside the virtual world, but I’ll take the academic copout that those are beyond the scope of this blog, and are sensitive information in a competitive environment.
Now let’s get to the good stuff. What does DOE methodology do for the race engineer?
One of the most useful tools to a race engineer when away from the computer is a Pareto chart based on the results of the DOE. Here’s an entirely fake example of one.
In this case we decided to look at roll angle and the effects each of these basic factors have on the vehicle roll angle at a given point on the racetrack that we have decided as being critical. Did you see the number of times I mentioned the end user being involved in choosing how to analyze this data? Pay attention to that sentence again. The effectiveness of a DOE approach is only as sharp as the person implementing it. There are numerous pitfalls here.
- Where do you look at the data on the track?
- What vehicle response(s) are critical to improving laptime?
- What factors were deemed critical enough to vary in the design?
- How many factors were varied?
- Was the design setup to include interaction of factors?
- In brutal honesty – how well does your simulation capture the response of your car?
- Will your setup stay close enough to the baseline that the DOE remains relevant?
You can see that, in order to effectively use this approach, you have to already have a good deal of knowledge of what you expect the outcome to be. You also have to be willing to accept when results are counterintuitive. I mentioned above about interactions, as you use higher order designs you began to capture interactions between your factors. This typically is when the human brain starts lagging in understanding – how does the engineer at the window of the car during practice comprehend how an interaction between all 7 factors listed above would affect the performance? This is when you must be back in front of the computer with the response surface calculation tool. The Pareto chart just helps you change front bar rate or the RR spring when the driver says the car rolls too much or too little – and don’t worry about the LF spring it won’t help here no matter how much you want it to. As in all real life, the previous example has a big “but” in it. What if your sim method doesn’t handle spring preload, bar preload, or jacking changes properly? Or maybe LF spring does affect roll, but you’ve just misled yourself away from that. Losing sucks, and being wrong is the geek’s version of losing.
Where do you look at the data on a given lap? Great question. This has huge implications on the quality of the fits, the impact on the setup, and the dreaded compromises that arise in any setup choice. This is trial and error, and no sane person would help a fellow competitor through this stage. Ever wonder why there are very few good SAE papers on racecar topics?
What vehicle responses are the most critical to improving lap time? When it comes to big stock cars (the vast majority of my time has been spent here), simply reducing roll angle isn’t going to make your car faster than everyone else’s, so the above example is a little off target. Simply matching dynamic crossweight to some magical number in the driver's and crew chief’s heads isn’t going to get it done either. The responses calculated are only limited by your imagination as to what defines better performance.
- What factors were deemed critical enough to vary in the design?
- How many were varied?
As the number of factors increases, so does the number of trials needed to capture the interactions of these factors. Think exponentially. This is where the multimode machines are making serious headway, no difference from CFD. What is important to your vehicle setup? What data about your model are clear enough to capture subtle changes? We all wish that tire data could be discreet to the point of being able to gnash our teeth endlessly over a very small pressure change. Vary inner and outer tire pressures (for a total of 8 factors and only 2 settings of each) in a full factorial DOE, and you’ve just signed up for 256 runs of simulation. Add only two more factors (let’s say front springs at only 2 levels) and that total is now 1024 runs. How fast is your PC? How accurate is that tire data in quantifying some change in the car? That may be better served by trying it with the driver strapped in and let the lap times make the call, except every major sanctioning body is trimming practice time as the years go by. When setting up your factors and their levels of variance, you have to allow a wide enough range to be helpful but not so wide that the response from one setting to the next is so different that the regression looks like a total mess. Maybe two levels of each factor aren’t enough, certainly when you are considering a spring change. No race team running for the big foam check at the end of the day brings only four spare springs! Now, consider that you decide you need to vary each of your 10 factors in 5 discreet values. That seems pretty reasonable. Put on your big boy pants, because you have just created a design with 9,765,625 simulation runs. Google fractional DOE design.
How well does your simulation capture the response of your car? As you can tell from the above discussion, this isn’t a topic to apply to your first runs in simulation. Get the validation work done, shoot holes in the data, and convince yourself that you are getting close. The alternative is wasting your time, which in this business tends to lead to unemployment.
You spent all week setting up the design and writing the script file to launch the sims and the array of CPUs burned through night and day without any interrupts in power or crashes in solution. Yeah, right, wait till you see some of the setups a five level full factorial design generates to run – you’ll be lucky if it can statically solve enough of them. On the final setup day, a decision is made to change the RF suspension geometry significantly. You now have a nice memorial to a lot of wasted time and effort. Once the setup winds its way outside of major parameters, the DOE becomes irrelevant. It’s a fact of life in this arena, you won’t be the first, second, or even 100th person this has happened to. The driver and team manager really aren’t going to want to hear about this. So, don’t bother. These are things that only other engineers are going to be sympathetic to, when we gather at the back of the garage to enjoy a Red Bull and complain to each other without giving away current projects.
DOE isn’t anything new. In reality, most of us were just waiting on hardware and software to catch up to concepts so it could be used. Most of my experience working on this topic happened between 1998 and 2004. The cost of such toys usually limits this approach to the big budget series. The tidbits and sarcastic remarks I have made all relate to working on this approach strictly in NASCAR Sprint Cup Racing at a couple of top level teams. I didn’t invent any of this. Like everything in racing, all of us claim to have invented it. My particular experiences happened while I was a part of a great group of engineers at previous teams. I have lived on every side of the race engineer role for the last decade, sometimes as an engineer helping support the race engineer’s job, sometimes as the race engineer, and sometimes as a crew chief using the race engineer to get the best out of the car, as quickly as possible. Luckily, my day job has nothing to do with simulation code, DOE, or race engineering these days, because this doesn’t even scratch the surface. I can guarantee you that all of the unknown faces in the Cup garage engineering these cars understand 100% of what was discussed here, and have for some time. Plenty of books have been written on the topic. I’ll leave you to go find them.
Thanks for reading,
Brandon Thomas
Red Bull Racing (USA)
Chief Design and Development Engineer
Tuesday, December 29, 2009
Setup Sheets, Part 2
Let's review the setup sheet layout. There are two fundamental layout concepts: by topic and by car location.
Sheets laid out by topic group similar items together. All the ride heights are together, all the shock info together, all the aero info together, and so on. For example, here's a prototype sports car sheet. This layout, although well done, omits some detail on brakes, tires, suspension geometry. It is used with "setup wheels", machined aluminum fixtures that replace real wheels and tires on the setup pad. Ride heights are calculated from measured drops to a point on top of the chassis, rather than actual measurements up from setup pad to the floor. Blue items are user input.
PDF - Print or Free DownloadXLS - Purchase Full Download
Sheets laid out by car location group information into a birds-eye view of the car. For each corner, you have alignment, tire data, springs, and so on. Information that doesn't fit that layout is placed on the center of the sheet or in a separate section. In a slightly different twist, the sheet that I use has chassis-mounted items and measurements like AR bars, ride heights, and packer gaps in the center, reducing the amount of info listed at the individual wheel. Here's a Swift 008a Formula Atlantic sheet. Note that this sheet includes some engineering calcs. It also has non-printing separate worksheets for vehicle dynamics and for shock build specs.
PDF - Print or Free DownloadXLS - Purchase Full Download
So, which layout to use? Both are popular, and both can be effective, if they are done well.
The main advantage of the topic layout is in grouping similar items together. For example, all the corner weights are in one spot, just like on the scale display. With so many different types of data to show, it can be a little scattered, unless it is carefully organized. The example posted here is one of the better ones.
The strength of the car location layout is in its ease of use. If you want to know something about the right front corner of the car, look at that part of the sheet. Some items, like brakes, corner weights, rake, or cooling, don't fall into the layout that well.
I use a layout that mixes some elements of both approaches. Go back and look at the sports car sample included in the Part 1 post, it's mine. Stuff mounted or measured at the wheels is out on the corners. Stuff mounted or measured on the chassis is down the middle. Front aero is at the front, rear aero at the rear. Gears, brakes, and weights are clumped together at their approximate location on the car. The next incarnation might get a new section for configuration file names for the data system, ECU, ABS, paddle shift system, etc.
Now, let's look at a layout for the worksheet that accompanies the car to the setup pad. This worksheet is a hands-on working document for use at the setup pad. Most of the teams I work with lack either the time, money, or resources for this to be used as a networked document on an smart phone or touch-screen PC. So, it's filled out by hand, and may or may not be scanned, depending on who needs copies and when. I like the cheap HP all-in-one printer/scanner/copier units for the trailer.
On the front, there are fields for Setdown, where we document how the car was found as it rolled off the track and onto the setup pad after preceding on-track session. The center column is used to enter the changes to make. The changes are then made, on or off the pad, and the car rolled on for adjustment. And then, the righthand column documents how the car rolled off the setup pad. On the back side, there is a worksheet for actually making the adjustments.
Yeah, I know, there's some redundency here, and opportunity to introduce error. We'll talk about this again in a later post, but cutting to the chase, I've found that a complete setup sheet doesn't work too well for calling out between-session changes. So, we do a setdown, fill in the changes, and finish the setup.
The example below is a scan of both the front and back pages of a setup worksheet after use. The links immediately above the form will download it, as well as blank versions of the front and back pages.
PDF - Print or Free Download Blank Form
XLS - Purchase Full Download Blank Form
PDF - Print and Free Download Completed Form
Tools and organization
OK, how about computing tools? Your choices are basically spreadsheet or data base. PDF forms with fillable fields don't have enough function. Spreadsheets offer plenty of formatting and calculating power, and are the near-universal solution. But, I've always wanted to try a database. The initial setup would be lot more work, but your setups would be available for the full power of database searching and reporting. I suspect that the ever-evolving nature of much racing might be responsible for the relative rarity of databases, since last year's setup is often no longer relevent. Series where you take the same basic car back to the same tracks, year after year, probably stand to benefit the most.
One thing is for sure. You have got to be diligent and organized in file naming and directory structure, or you will soon have an unworkable jumble of setup sheets files. Here's the file naming convention that I use:
Setup Seb090307 A04 P1 Start.xls
Sheets laid out by topic group similar items together. All the ride heights are together, all the shock info together, all the aero info together, and so on. For example, here's a prototype sports car sheet. This layout, although well done, omits some detail on brakes, tires, suspension geometry. It is used with "setup wheels", machined aluminum fixtures that replace real wheels and tires on the setup pad. Ride heights are calculated from measured drops to a point on top of the chassis, rather than actual measurements up from setup pad to the floor. Blue items are user input.
PDF - Print or Free DownloadXLS - Purchase Full Download
Sheets laid out by car location group information into a birds-eye view of the car. For each corner, you have alignment, tire data, springs, and so on. Information that doesn't fit that layout is placed on the center of the sheet or in a separate section. In a slightly different twist, the sheet that I use has chassis-mounted items and measurements like AR bars, ride heights, and packer gaps in the center, reducing the amount of info listed at the individual wheel. Here's a Swift 008a Formula Atlantic sheet. Note that this sheet includes some engineering calcs. It also has non-printing separate worksheets for vehicle dynamics and for shock build specs.
PDF - Print or Free DownloadXLS - Purchase Full Download
So, which layout to use? Both are popular, and both can be effective, if they are done well.
The main advantage of the topic layout is in grouping similar items together. For example, all the corner weights are in one spot, just like on the scale display. With so many different types of data to show, it can be a little scattered, unless it is carefully organized. The example posted here is one of the better ones.
The strength of the car location layout is in its ease of use. If you want to know something about the right front corner of the car, look at that part of the sheet. Some items, like brakes, corner weights, rake, or cooling, don't fall into the layout that well.
I use a layout that mixes some elements of both approaches. Go back and look at the sports car sample included in the Part 1 post, it's mine. Stuff mounted or measured at the wheels is out on the corners. Stuff mounted or measured on the chassis is down the middle. Front aero is at the front, rear aero at the rear. Gears, brakes, and weights are clumped together at their approximate location on the car. The next incarnation might get a new section for configuration file names for the data system, ECU, ABS, paddle shift system, etc.
Now, let's look at a layout for the worksheet that accompanies the car to the setup pad. This worksheet is a hands-on working document for use at the setup pad. Most of the teams I work with lack either the time, money, or resources for this to be used as a networked document on an smart phone or touch-screen PC. So, it's filled out by hand, and may or may not be scanned, depending on who needs copies and when. I like the cheap HP all-in-one printer/scanner/copier units for the trailer.
On the front, there are fields for Setdown, where we document how the car was found as it rolled off the track and onto the setup pad after preceding on-track session. The center column is used to enter the changes to make. The changes are then made, on or off the pad, and the car rolled on for adjustment. And then, the righthand column documents how the car rolled off the setup pad. On the back side, there is a worksheet for actually making the adjustments.
Yeah, I know, there's some redundency here, and opportunity to introduce error. We'll talk about this again in a later post, but cutting to the chase, I've found that a complete setup sheet doesn't work too well for calling out between-session changes. So, we do a setdown, fill in the changes, and finish the setup.
The example below is a scan of both the front and back pages of a setup worksheet after use. The links immediately above the form will download it, as well as blank versions of the front and back pages.
PDF - Print or Free Download Blank Form
XLS - Purchase Full Download Blank Form
PDF - Print and Free Download Completed Form
Tools and organization
OK, how about computing tools? Your choices are basically spreadsheet or data base. PDF forms with fillable fields don't have enough function. Spreadsheets offer plenty of formatting and calculating power, and are the near-universal solution. But, I've always wanted to try a database. The initial setup would be lot more work, but your setups would be available for the full power of database searching and reporting. I suspect that the ever-evolving nature of much racing might be responsible for the relative rarity of databases, since last year's setup is often no longer relevent. Series where you take the same basic car back to the same tracks, year after year, probably stand to benefit the most.
One thing is for sure. You have got to be diligent and organized in file naming and directory structure, or you will soon have an unworkable jumble of setup sheets files. Here's the file naming convention that I use:
Setup Seb090307 A04 P1 Start.xls
- Sebring is the track
- March 7, 2009 is the race date (not the creation date of the setup sheet)
- Chassis number A04
- This sheet shows how the car started the first official practice session
I place all the sheets for an event into a directory exclusive to that event. Use real-time archival software pointed at the location of all the setup sheets. You don't want to lose a year's worth of setups when the notebook hard drive crashes at the track.
Remembering that a setup sheet is a vehicle for communication, the next post will get into the process of using it. Once that's done, we'll dig deeper into content.
Monday, December 28, 2009
Setup Sheets, Part 1
I'm kinda excited about this multi-part series, since it's a bit of a departure from recent posts. We're going to review setup sheets in fairly complete detail, so this isn't your usual short-attention-span blog post. You'll be able to download PDF samples and working Excel spreadsheets from Scribd. Here we go...
What is a setup sheet, anyway?
In simple terms, it is a document that details the configuration and adjustment of a race car.
And what is it used for?
What is a setup sheet, anyway?
In simple terms, it is a document that details the configuration and adjustment of a race car.
And what is it used for?
- Define all the setup adjustments, like alignment, ride height, etc.
- Specify commonly swapped parts, like springs, gear ratios, anti-roll bars, etc.
- Document the car setup, for later reference
- Possibly, link to analysis or simulation software to provide vehicle dynamics details
The simplest setup sheets are handwritten onto a basic blank form. In this guise, it is mainly a working document for crew adjustments to the car on the setup pad. It probably has no more than the following content, and maybe less, depending on what items may be non-adjustable, non-changeable, or non-existent on a specific car:
- Ride heights
- Spring rates
- Anti-roll bar sizes and adjustments
- Shock adjustments and gas pressures
- Camber, caster, and toe settings
- Aero adjustments, such as angles and dimensions
- Corner weights and percentages
Here's the catch. If the setup sheet is to be a complete and unambiguous definition of how the car is configured, there is inevitably more information required. Sometimes, lots more. The possible list is endless, but here are some common items, in no particular order:
- Bump rubber spec and packer gaps
- Third spring and damper components and adjustments
- Optional aero components and how they are installed or adjusted
- Cooling configuration, both components and blanking
- Gear ratios and differential setup
- Optional suspension geometry and components
- Brake components, pad/rotor material, master cylinders, bias setup
- Multiple ride heights - aero components vs. structural/suspension
- Specific assembly instructions - part numbers, shims, etc.
- Tire sizes, compounds, and constructions
- Tire pressures for both the setup pad and the grid
- Driver weight and fuel load for the setup pad, starting fuel load for the track
- Shock build spec
- Part numbers or serial numbers for specific components and assemblies
- Spring and/or pushrod installed length. Rocker ratio and position.
- Ballast weight, configuration, position
This can get out of hand. Still, we absolutely have to be able to completely and unambiguously define how the car is expected to be configured when it rolls onto the track. At some time in the future, we need to be able to completely and unambiguously recall that configuration by reviewing the setup sheet.
Taking things a step further, there are two additional types of information that sometimes show up on setup sheets. They are specific component serial numbers, for use in part lifing, and vehicle dynamics calculations, such as wheel rates. I personally choose not to include these on my setup sheets. They aren't essential to defining the car configuration and clutter up its use by the crew. If needed, I think they should be on a separate document, or an "engineer's version" that can be separately printed.
We have to remember that a race car is always changing, and we race or test it as a snapshot in time. Some of these evolving changes are permanent, some not. They rarely seem to fit the existing format for the setup sheet. We have to decide whether, when, and how to indicate these changes on the setup sheet. I tend to mention permanent modifications in the comments section at the time they first appear, then delete them on future sheets - a solution I'll admit to being imperfect.
Sharp readers will have noticed no mention so far of engine configuration and tuning, nor of configuration options and file names for ECUs, data acquisition, traction control, no-lift shift, ABS, or any other electronic systems. Engines tend to be assembled, tuned, and maintained by a separate group which may or may not be part of the team. The electronics are typically maintained and tuned by one or more specialists, a process that can be a bit undisciplined, if nonetheless superbly executed. In an oddity of how things have evolved, the setup sheet is typically the configuration for the rest of the car.
One possible solution to some of these concerns is a "build sheet", produced either as a separate document or as a different print option, similar to what we've discussed for components and engineering data. It can include all sorts of information, like serial numbers, part numbers, modifications, file names, and so on.
So, here's my recommendation:
Use a comprehensive setup sheet that defines everything adjustable or changeable on the race car. Permanent modifications are either excluded or get a mention in the notes section at the time they are done. If it's appropriate for your situation, create a separate build sheet, either to define the car more fully or for part serial numbers. Keep engineering calcs off the main sheet. A worksheet accompanies the car to the setup pad for note-taking during the setup process.
To give you something to think about until the next post, here's a recent sports car racing prototype setup sheet. This sheet is fairly comprehensive, yet this car lacks certain suspension geometry and aero options that I've had on other recent setups. Numbers and other fields, of course, are changed to disguise the real setup. Fields calculated internally by the setup sheet show in blue. If you purchase the full XLS, you'll see the non-printing calcs for ride heights and gears.
Friday, December 25, 2009
Using Scribd
Hi folks.
There's a major new series coming for the Race Engineer blog. We'll be covering setup sheets in quite a bit of detail.
And, we're going to offer content for download in the Setup Sheet series, as well as in future ones. I'll be using http://www.scribd.com/. If you're not familiar with the site, it's sort of analogous to iTunes, only for documents instead of music and video.
Every document will be available free as a PDF, either to print or download. Not free beer, not free lunch, but the best I can do in a blog.
Many will also be available for purchase in the native format, which will typically be XLS. For forms with a lot of formatting and information, like setup sheets, this will save quite a bit of time compared to creating your own version from scratch. For real engineering tools, you get all the calcs behind the visible input and results.
I puzzled some over pricing. Some of this stuff is pretty simple, but some of it represents literally days, if not weeks, of work. Radiohead's pricing strategy of letting the user decide how much to pay was intriguing, but Scribd doesn't work that way. I do need to get something for my effort, but on the other hand I want to make this stuff widely available. In the end, I decided to make the forms $10 each, unless they are really simple. You're already paying that for an album download on iTunes or Amazon. And it's waaaaay cheap compared to the time you'd spend duplicating it. Real engineering tools will be priced according to their content.
The imbedded PDFs will display a frame from Scribd. Preceding each will be two links, one to the PDF, one to the native format.
Click the PDF link to print or get the free download.
Click the native format link to purchase. There will be a big yellow button "Buy Now" on the right side of the screen which takes you to the typical online purchase dialog to enter your credit card info.
The Scribd site asks you to register to get the free download or print. Wish they didn't do that, but at least it's free. Oh well...
As a sample, here's a setup sheet for an IRL car in 1998. Left or right click on the Scribd window to activate the various controls, zoom, and so on.
PDF - Print or Free Download
XLS - Purchase Download
Please drop me a comment if all this doesn't work correctly for you.
There's a major new series coming for the Race Engineer blog. We'll be covering setup sheets in quite a bit of detail.
And, we're going to offer content for download in the Setup Sheet series, as well as in future ones. I'll be using http://www.scribd.com/. If you're not familiar with the site, it's sort of analogous to iTunes, only for documents instead of music and video.
Every document will be available free as a PDF, either to print or download. Not free beer, not free lunch, but the best I can do in a blog.
Many will also be available for purchase in the native format, which will typically be XLS. For forms with a lot of formatting and information, like setup sheets, this will save quite a bit of time compared to creating your own version from scratch. For real engineering tools, you get all the calcs behind the visible input and results.
I puzzled some over pricing. Some of this stuff is pretty simple, but some of it represents literally days, if not weeks, of work. Radiohead's pricing strategy of letting the user decide how much to pay was intriguing, but Scribd doesn't work that way. I do need to get something for my effort, but on the other hand I want to make this stuff widely available. In the end, I decided to make the forms $10 each, unless they are really simple. You're already paying that for an album download on iTunes or Amazon. And it's waaaaay cheap compared to the time you'd spend duplicating it. Real engineering tools will be priced according to their content.
The imbedded PDFs will display a frame from Scribd. Preceding each will be two links, one to the PDF, one to the native format.
Click the PDF link to print or get the free download.
Click the native format link to purchase. There will be a big yellow button "Buy Now" on the right side of the screen which takes you to the typical online purchase dialog to enter your credit card info.
The Scribd site asks you to register to get the free download or print. Wish they didn't do that, but at least it's free. Oh well...
As a sample, here's a setup sheet for an IRL car in 1998. Left or right click on the Scribd window to activate the various controls, zoom, and so on.
PDF - Print or Free Download
XLS - Purchase Download
Please drop me a comment if all this doesn't work correctly for you.
Thursday, October 29, 2009
Vehicle Dynamics, Vol. 1 - Thinking in 3 Dimensions
At the outset, I promised that this blog wouldn't be a vehicle dynamics tutorial. Still true. Get out your Milliken, Gillespie, and even Carroll Smith's timeless "Tune to Win".
But, here's an observation.
When many race engineers and chassis tuners think about handling, they focus heavily on roll moment and roll stiffness. That's a vital topic, but it's only part of the total handling equation.
The car operates in 3-dimensional space, with forces and moments acting on it along the X, Y, and Z axes (longitudinal, lateral, and vertical to regular mortals). At any point in time, its handling is dependent on how it reacts to ALL SIX of those forces and moments. Limiting your thinking to roll only addresses lateral forces and longitudinal moments.
For example:
1-Savvy oval track engineers have long been focused on the vertical forces from both banking and aerodynamics.
2-When a car is cornering, it is rotating around its Z (vertical) axis. The are a number of very significant sources of moments around that axis, some of which are under the control of the engineer.
There is much to be learned from data acquisition. Install a steering travel potentiometer calibrated in spindle degrees. Install a 3-axis accelerometer and a yaw rate sensor. Just in the Z-axis, you can calculate understeer gradient (see Gillespie), yaw gain (yaw rate divided by steering), and stability index (see Danny Nowlan's excellent recent series in Race Car Engineering magazine). Use your imagination. There's more.
Apologies for the lack of illustrating diagrams. I'm still too busy with real work to explore the tools that Blogspot offers. Eventually.
The proverbial word to the proverbial wise should be sufficient. Go for it!
But, here's an observation.
When many race engineers and chassis tuners think about handling, they focus heavily on roll moment and roll stiffness. That's a vital topic, but it's only part of the total handling equation.
The car operates in 3-dimensional space, with forces and moments acting on it along the X, Y, and Z axes (longitudinal, lateral, and vertical to regular mortals). At any point in time, its handling is dependent on how it reacts to ALL SIX of those forces and moments. Limiting your thinking to roll only addresses lateral forces and longitudinal moments.
For example:
1-Savvy oval track engineers have long been focused on the vertical forces from both banking and aerodynamics.
2-When a car is cornering, it is rotating around its Z (vertical) axis. The are a number of very significant sources of moments around that axis, some of which are under the control of the engineer.
There is much to be learned from data acquisition. Install a steering travel potentiometer calibrated in spindle degrees. Install a 3-axis accelerometer and a yaw rate sensor. Just in the Z-axis, you can calculate understeer gradient (see Gillespie), yaw gain (yaw rate divided by steering), and stability index (see Danny Nowlan's excellent recent series in Race Car Engineering magazine). Use your imagination. There's more.
Apologies for the lack of illustrating diagrams. I'm still too busy with real work to explore the tools that Blogspot offers. Eventually.
The proverbial word to the proverbial wise should be sufficient. Go for it!
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