Request for Analysis of Proposed Wheel Base Rule Change

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TXDerbyDad
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by TXDerbyDad »

FatSebastian wrote:
*5 J's* wrote:You can, but...
That's why we don't recommend it. ;) However, we sometimes build with 2 rows of six cubes.
We've done it 2 years in a row with 7 cars and had no problems.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by TXDerbyDad »

Stan Pope wrote:The purpose of this change is to reduce the advantage obtained by using expensive ballast.
This is the part I simply don't understand. Lead may be cheap, but it's toxic, and unfortunately is much more readily absorbed by children than adults. Tungsten is safer and not terribly expensive, especially if the cost is amortized over multiple race years. We re-use our "expensive" ballast every year, and it's one less toxic substance I have to worry about when doing the derby. Personally, we'll never use lead again at my house.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Stan Pope »

Don't assume "lead!"

Suppose that a different "maximum distance" is selected. For instance, suppose that the rule were "All axles must be within 6-3/8" of each end of the car." If one chose to max the wheelbase, this would be approximately the same as most "extended wheelbase rules." However, what if one chose to use a wheelbase of 4-3/4"? What does the car look like then if you fully utilize the envelope? What options for weight does that open?
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by resullivan »

Why not just have everyone bring a car, put a number on it, then do a drawing and award cars at random. This will ensure that no matter how hard you worked (or didn't work) that you still have a chance to win. Heck, why even have cars? Just have everyone show up and award the trophies at random. Hmm, no that wouldn't be any fun. Ok, I got it. For a 3 lane track build 2 really slow cars and let everyone race against them. Award a trophy to everyone. Problem solved!
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Stan Pope »

resullivan wrote:Why not just have everyone bring a car, put a number on it, then do a drawing and award cars at random. This will ensure that no matter how hard you worked (or didn't work) that you still have a chance to win. Heck, why even have cars? Just have everyone show up and award the trophies at random. Hmm, no that wouldn't be any fun. Ok, I got it. For a 3 lane track build 2 really slow cars and let everyone race against them. Award a trophy to everyone. Problem solved!
Sorry, that's a solution for a different problem!

An answer to the question posed ("what if one chose to use a wheelbase of 4-3/4"? What does the car look like then if you fully utilize the envelope? What options for weight does that open?") is
. The rear axles are 6-3/8" from the nose of the car. That is typical for an extended wheelbase car.
. The front axles are 1-5/8" from the nose of the car.
. The rear of the car is 1-5/8" from the rear axles (6-3/8" from the front axles).

No potential energy advantage is gained vs normal extended wheel base car.
There is room behind the rear axle for about 2-1/2 times volume vs normal extended wheel base car without increasing the car body thickness. This puts other lower density materials such as steel or zinc "in the running" without compromising either body thickness or CM location.
Stan
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by knotthed »

Stan,

I think it might curtail some learning opportunities and make inspections take longer.

What is your tolerance for this alleged dimension? How will it be measured equally by all of the packs in your district? What is the Gage R&R on the measurement method?

What are you going to tell the kid that cannot race because his wheels are in the wrong place?

The bottom line is that the people that want to put in the effort will do well, others will not(same as with Life).

As a race coordinator, I have practically handed people a recipe for a respectably fast car and yet they still choose not to read the emails.

As others have mentioned, the Tungsten can easily be reused. Especially utilizing the weighting approach of current league racers. We have went from epoxying in our weight(not easy to reuse) in the beginning to just using two kinds of tape now and have not had any problems.

The steel and zinc weights are a joke, period. Look at the materials densities comparatively.

Tungsten and Lead are the most viable options.

If you want to remove the advantage of tungsten ballast, why not just limit your COM location?

Measuring COM would at least make people measure something that has a sizeable impact on performance.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Darin McGrew »

knotthed wrote:What is your tolerance for this alleged dimension? How will it be measured equally by all of the packs in your district? What is the Gage R&R on the measurement method?
I don't see Stan's proposed rule creating any more of a problem than common rules on car length, ground clearance, original wheelbase, minimum width, etc. Adding lines to a car inspection gauge to check nose-to-rear-axle and tail-to-front-axle distances shouldn't be that hard.
knotthed wrote:What are you going to tell the kid that cannot race because his wheels are in the wrong place?
What are you going to tell the kid that cannot race because his car violates some other rule? This isn't a new problem. Other derbies have imposed various limits on the dimensions of the cars, including wheelbase limitations.
knotthed wrote:The bottom line is that the people that want to put in the effort will do well, others will not(same as with Life).
True. But the goal here is to avoid having expensive aftermarket parts (in this case, tungsten weights) become essential to building a competitive car. In spirit, it's no different from restrictions on wheels that exclude expensive third-party lathed wheels.
knotthed wrote:The steel and zinc weights are a joke, period. Look at the materials densities comparatively.
Stan's point is that this simple wheelbase rule could allow cars using non-lead, non-tungsten weights to be competitive, considering both their COM location and their aerodynamic cross section.
knotthed wrote:If you want to remove the advantage of tungsten ballast, why not just limit your COM location?
Building a car inspection gauge for COM location would be much more problematic than building a car inspection gauge for Stan's proposed wheelbase rule.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Stan Pope »

Another possible plus is that the offered rule change brings even more aerodynamic fenders into play, expanding the opportunities for learning. (Current length/wheelbase limits almost eliminate any opportunity to explore (and take advantage of) trailing edge aerodynamic effects.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by knotthed »

Boy, I dislike the quotes - I am having a bit of a go at it.
knotthed wrote:
knotthed wrote:What is your tolerance for this alleged dimension? How will it be measured equally by all of the packs in your district? What is the Gage R&R on the measurement method?
Darin McGrew wrote:I don't see Stan's proposed rule creating any more of a problem than common rules on car length, ground clearance, original wheelbase, minimum width, etc. Adding lines to a car inspection gauge to check nose-to-rear-axle and tail-to-front-axle distances shouldn't be that hard.
Darin, how accurately do you think this can be measured to? 1/16"? Unless I am not understanding your inspection method, there would certainly be some form of parallax error possible. Would it not be unfair to allow one racers wheelbase to be farther back than anothers? Good students will push the envelope anyway while those that do not care will not.
knotthed wrote:What are you going to tell the kid that cannot race because his wheels are in the wrong place?
Darin McGrew wrote: What are you going to tell the kid that cannot race because his car violates some other rule? This isn't a new problem. Other derbies have imposed various limits on the dimensions of the cars, including wheelbase limitations.
Exactly my point! why restrict it, why not allow any wheel base they want. How about not allowing a car to race that was built backwards using a slots ruleset. Boy it sure isn't fair for him to have such a short nose to rear axle distance, compared to others that built it the other way around.

Despite the rules having something as simple as a minimum width - we had a scout show up with a car that did not meet it this year.....
Knotthed wrote:The bottom line is that the people that want to put in the effort will do well, others will not(same as with Life).
Darin McGrew wrote: True. But the goal here is to avoid having expensive aftermarket parts (in this case, tungsten weights) become essential to building a competitive car. In spirit, it's no different from restrictions on wheels that exclude expensive third-party lathed wheels.
"Expensive aftermarket parts", where do I begin? I find it hard to believe that a scout cannot affford $17 dollars worth of tungsten weights for 5 years of racing....... If not send them to my house - I will put them to work and they can earn the $17 needed to buy the weights instead of playing xbox or DS at their house.
Same goes for a bottle of oil! One bottle used properly should last all 5 years.
Knotthed wrote:The steel and zinc weights are a joke, period. Look at the materials densities comparatively.
Darin McGrew wrote: Stan's point is that this simple wheelbase rule could allow cars using non-lead, non-tungsten weights to be competitive, considering both their COM location and their aerodynamic cross section.
I understand the premise of his rule. I was just sharing my thoughts on it. If you want to control COM, why not measure COM - maybe the parents will take interest it what it is (not likely) but hey - you can explain what your doing and why it matters when you're measuring it. This would also allow, the user to use whatever kind of weights he see's fit or wants his scout to use. Another approach would be to prohibit the use of Tungsten - not practical though from an inspection standpoint.
Knotthed wrote:If you want to remove the advantage of tungsten ballast, why not just limit your COM location?
Darin McGrew wrote: Building a car inspection gauge for COM location would be much more problematic than building a car inspection gauge for Stan's proposed wheelbase rule.
To measure, I don't think it would be any harder than your lines on the box idea above and it would remove any parallax error. Draw a pencil line on the bottom of the car and state that it must balance with the line visible to the appropriate side on something like the car balance stand from maxv.

Perhaps this would still allow aero and mass concentration advantages.

On another subject, how can you ensure that each scouts pinewood is equal?

I applaud Stan for considering the consequences of a rule change at a District level, it affects a lot of people.

I think the goal should be for an open ruleset that does not allow uninspectable things to cause an unfair advantage. Also, the ruleset should be accompanied by an inspection process/procedure that anyone off the street could follow and perform that provides equal treatment to the cars being inspected.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Stan Pope »

knotthed wrote:I applaud Stan for considering the consequences of a rule change at a District level, it affects a lot of people.
Thank you!

Yes, district rules (car specs) are important to all who will possibly participate in district racing, and we who participate in configuring the specs owe it to all to do our best to keep the rules supporting the underlying goals. And after we have done our best, we encourage (and make it easy for) pack leadership to incorporate those rules into their programs so that the transition from pack racing to district racing is graceful with effort expended on improving the car and not changing it to comply with different specs.
knotthed wrote:I think the goal should be for an open ruleset that does not allow uninspectable things to cause an unfair advantage.
I think that the offered axle location rule is easily inspected. Our "short track section" that inspects for under-belly clearance currently has a pin at each end to test for nose height compliance and could easily have index points added that can be compared to the axle when the car is positioned against the end-stops.
knotthed wrote:Also, the ruleset should be accompanied by an inspection process/procedure that anyone off the street could follow and perform that provides equal treatment to the cars being inspected.
Curiously, I am one of the few who published a detailed inspection sequence along with the rules! Don't know if recent chairs have maintained / continued it, but I left 'em a good plan that could be divided into inspection steps to spread the work over several inspectors and still maintain consistency in inspection! That is, for each technical aspect, ALL cars are inspected by the same person!
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by knotthed »

Stan Pope wrote:I think that the offered axle location rule is easily inspected. Our "short track section" that inspects for under-belly clearance currently has a pin at each end to test for nose height compliance and could easily have index points added that can be compared to the axle when the car is positioned against the end-stops.
Stan, that is great for your group, but what about all the other packs that don't have the same setup? You need to make it easier for the packs, not harder.

Let's go the other way with this, since we think we need to level the playing field;

(Some parents may not have access to a drill or dremel)
Axles may not be modified in anyway shape or form. You may not remove the burrs or sand the axles in anyway shape or form. You may not taper the backside of the head of the axle.

(Some parents may not have access to anything to fix or measure the condition of the wheels)
Wheels may not be modified in anyway shape or form. No coning hubs, no removing the step in the outer hub. No wheel bore treatments of anykind, no wax, no polish, etc....

In fact to make it fair, we are just going to issue you your wheels and axles an hour before the race.

Where does it end?

You cannot level the playing field. Those that wish to excel will and those that do not will not.

The best chance you have at levelling the field is to give the same access to knowledge, supplies and equipment to all participants in the race.

But we still have this thing called Skill that is unfair. How can we regulate that too?
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Darin McGrew »

knotthed wrote:Darin, how accurately do you think this can be measured to? 1/16"?
Honestly, I don't know. For our derbies, we don't use a car inspection gauge (other than a section of track to test the "must fit the track" rule) and we don't limit the wheelbase. But I know that a lot of derbies do use car inspection gauges to test cars against their requirements for car length and wheelbase. There are lots of derbies that restrict cars to the stock wheelbase, and they don't seem to run into any big problems enforcing that rule. Stan's proposed rule shouldn't be any more difficult to enforce.
knotthed wrote:Despite the rules having something as simple as a minimum width - we had a scout show up with a car that did not meet it this year.....
Yeah, we've had that happen too. And we've had cars come in severely overweight. And we've had cars come in with the wrong wheels and axles. And so on. So we helped them fix their cars before checking them in. That's one of the big reasons why I like holding the final check-in a few days before the race itself. But I digress...
knotthed wrote:On another subject, how can you ensure that each scouts pinewood is equal?
I don't think they need to be equal. But I do think they need to be close enough that choosing the right block isn't a make-or-break decision. We've never used BSA Pinewood Derby kits, but this hasn't been a problem with the kits we have used.
knotthed wrote:Stan, that is great for your group, but what about all the other packs that don't have the same setup? You need to make it easier for the packs, not harder.
What's harder for struggling packs? Making sure everyone has tungsten weights so they can be competitive, or measuring the distance between the nose and rear axle, and the distance between the tail and front axle? Personally, I think enforcing a clear rule like the one Stan described would be easier.
knotthed wrote:You cannot level the playing field. Those that wish to excel will and those that do not will not.
At its core, a derby is about children working on a simple construction project with parents and/or other trusted adults. Together, they use the block, axles, and wheels in the kit to build a small car that rolls down an inclined track.

It shouldn't be about buying the best pre-built car, or about buying the best third-party parts and supplies. IMHO, and all that.

Stan's proposed rule is a simple, enforceable rule that is intended to eliminate the need for expensive tungsten weights. I see that as something that supports the core purpose of the derby, not something that undermines it.
knotthed wrote:The best chance you have at levelling the field is to give the same access to knowledge, supplies and equipment to all participants in the race.
For our derby, we spend much more time and money on our workshops than we do on the race itself. We share plenty of knowledge, supplies, and equipment.

But I don't think it's a bad thing to focus the event on the things a child and adult can do together, rather than on things that must be bought.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Stan Pope »

knotthed wrote:Let's go the other way with this, since we think we need to level the playing field;
Please don't include me as having such a goal!

My goal is to make it competitively feasible to avoid expensive components. I really dislike the idea that to build a competitive car, one must spend a lot of $. I'd like the rules to facilitate the team learning to build a good car, including preparation of the parts, and not needing to buy "finished parts" in order to build a good car.

For instance, a team that recognizes the competitive value of a well turned wheel can usually find someone who is willing to give them time on a lathe and teach them what to do to convert their "average out of the box wheel" into a "competitive wheel." That team can not take their "scrap box weights" to a friend's house and be shown how to reconfigure them into tungsten.

Some teams may ultimately decide to "buy" rather than "build", but that should be their choice in how to be competitive.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by resullivan »

I started to write a long response, but I decided to stick to your question about your proposed rule change.

1) I think there are more advantages to using a more dense material than COM. In other words, I still think using tungsten will give you an advantage.
2) I don't know what it takes to be competitive in your district, but in ours the $20 of tungsten is the least of our costs.
3) I am not sure if your intent is to save the people that currently buy tungsten money, or to attempt to make the people that don't use it more competitive. If it is the later, I don't think this rule will help. The people that win with your current rules will win with your new one.
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Re: Request for Analysis of Proposed Wheel Base Rule Change

Post by Speedster »

I suspect Stan's rule would change nothing. Once a District allows other than a 4 3/8" wheelbase, using slots, a whole lot changes. Four ounces of 1/4" tungsten cubes would cost a racer $4.88 per year and that includes shipping. If the racer joined with 4 friends he would get free shipping and it would cost him $3.59 per year. That's a little less then a penny a day. Is it really cost or perhaps disinterest? Tungsten cubes are a lot harder to work with then drilling a hole and inserting a lead rod. There was one wafer car in our District races this year and it appeared in the Tiger class. Yes, he won. All the other cars, other then the cars of my 2 scouts, had lots of wood. No matter what was used for weight they were limited on the amount that could be added. My scouts had an advantage before the pin dropped - OK, except for the one little Hot Rod that beat us since we all raced the Bear class.
I think every single rule made, from the most basic to the generous rules of the Mid America, benefits the scout who loves the Pinewood Derby and is willing to put in the work that it takes to build a fast car.

Is there really a scout District that allows lathed wheels?
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