Accurate testing on a shorter track?

Discussions on buying, building or rehabbing a race track. Topics like plans, materials, tools, construction, finishing, commercially available tracks, and so on.
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Vitamin K
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Re: Accurate testing on a shorter track?

Post by Vitamin K » Tue Oct 22, 2013 5:53 am

Just to clear up a few things:

- I do intend to outfit our Pack's track with an electronic finish line before the next Pack Derby race. I've got the Arduino and parts in a nice little box on my desk. All I need is time, heh. My main goal for /that/ project is to assist in scoring though. Not certain whether or not I'll have time to add a circuit to the start gate and displays for the actual time, however.

- For the test track I want to build, I had originally envisioned a two-lane, timerless track so that I could compare iterative builds of cars to see how they ran in comparison with each other. I'd also use it to check for things line stability, rail-riding, wobble, etc. I'm not certain I see a lot of value in a timer for a homemade cheapie track, because the times you get on that aren't going to be the same as the times you get on, say, a metal Best Track. I guess the more data you can collect, the better, but, in the beginning, I just plan to be testing Car A against Car B (and Car C and Car D, etc, etc...)

- The main reason I made this thread was to answer the question of: "If Car A beats Car B on a 40 foot aluminum track, wlll Car A beat Car B on my homebuilt wooden 20-30 foot jobbie?" (And vice versa).

Thanks for all of your help and input so far, guys.



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Re: Accurate testing on a shorter track?

Post by bracketracer » Tue Oct 22, 2013 10:02 am

If I might throw in my .02....... IMHO, any test track to compare times or just eyeball speeds of two cars will net you a faster car. I ran our cars on our homebuilt 32' track, then ran them on a 42' Bestrack, calculated the difference, and was able to use that "correction factor" to estimate how much more speed we needed to find to move up.

Need an example? It looks like this:
Time on 32' home track- 2.6955
Time on 42' Besttrack- 2.9755
2.9755 divided by 2.6955 equals 1.1038768
I wanted the car to go 2.970 on the Besttrack, so.....2.970 divided by 1.1038768 means I need to see 2.6905 (or better!) at home. It's not perfect but it'll at least get you close!

My homebuilt track & timer is pretty consistent, I usually see a std dev under .0015 unless I'm tweaking the car between runs.

My son ran last year's second place Tiger Cub car on this track, built a new car to the same rules with what we learned from playing this summer, and it picked up about .090 sec! Since he only missed Pack Grand Champion by .030 sec, my son is excited to say the least!



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Stan Pope
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Re: Accurate testing on a shorter track?

Post by Stan Pope » Tue Oct 22, 2013 10:04 am

Vitamin K wrote:...
- The main reason I made this thread was to answer the question of: "If Car A beats Car B on a 40 foot aluminum track, wlll Car A beat Car B on my homebuilt wooden 20-30 foot jobbie?" (And vice versa).
Do you feel like you have received an answer?


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Re: Accurate testing on a shorter track?

Post by gpraceman » Tue Oct 22, 2013 10:16 am

Vitamin K wrote:- The main reason I made this thread was to answer the question of: "If Car A beats Car B on a 40 foot aluminum track, wlll Car A beat Car B on my homebuilt wooden 20-30 foot jobbie?" (And vice versa).
I'd say maybe to that. After observing scores of races, I have seen many times where Car A will not pass Car B until the last track section. So, on a shorter track, Car B would have been the winner. You can use a shorter track to tune a car, but ideally testing on the same type and length of track that will be raced on will be a better indicator of race performance.


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Re: Accurate testing on a shorter track?

Post by Rukkian » Tue Oct 22, 2013 12:40 pm

Maybe I am not thinking about everything, but one way we have tried to combat that is our track at home does not have a set starting point, we just prop it up on either a bench, or window sill, etc. We then do testing with steeper angles to see how they do down the hill and through the transition, and then switch to a lower, more gradual hill and do a slow test (sometimes just enough to get them to the finish). This seems to let us know where we need help, but usually we are pretty good from the start with just needing to tweak the amount of steer into the rail.



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Re: Accurate testing on a shorter track?

Post by FatSebastian » Tue Oct 22, 2013 4:21 pm

Vitamin K wrote:I'm not certain I see a lot of value in a timer for a homemade cheapie track, because the times you get on that aren't going to be the same as the times you get on, say, a metal Best Track.
You might consider this thread.

For the same reasons you might question the value of adding a timer to a test track, I might question the value of adding an extra 10' of flat. As you say, the tracks are different, so there is no guaranteeing that improving performance with respect to one environmental variable will have the same effect in the other environment.



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Vitamin K
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Re: Accurate testing on a shorter track?

Post by Vitamin K » Tue Oct 22, 2013 7:53 pm

Stan Pope wrote:
Vitamin K wrote:...
- The main reason I made this thread was to answer the question of: "If Car A beats Car B on a 40 foot aluminum track, wlll Car A beat Car B on my homebuilt wooden 20-30 foot jobbie?" (And vice versa).
Do you feel like you have received an answer?
Yes, I think so. Though I'm open to more input and speculation if anybody is inclined to wax eloquent on test tracking. :)
qpraceman wrote:
Vitamin K wrote: The main reason I made this thread was to answer the question of: "If Car A beats Car B on a 40 foot aluminum track, wlll Car A beat Car B on my homebuilt wooden 20-30 foot jobbie?" (And vice versa).
I'd say maybe to that. After observing scores of races, I have seen many times where Car A will not pass Car B until the last track section. So, on a shorter track, Car B would have been the winner. You can use a shorter track to tune a car, but ideally testing on the same type and length of track that will be raced on will be a better indicator of race performance.
Auugh, not what I wanted to hear! ;) I may have to just put those cases aside and focus on what I'm able to gauge, since laying out a full track might just not be possible.
Rukkian wrote: Maybe I am not thinking about everything, but one way we have tried to combat that is our track at home does not have a set starting point, we just prop it up on either a bench, or window sill, etc. We then do testing with steeper angles to see how they do down the hill and through the transition, and then switch to a lower, more gradual hill and do a slow test (sometimes just enough to get them to the finish). This seems to let us know where we need help, but usually we are pretty good from the start with just needing to tweak the amount of steer into the rail.
Now that is an approach that I hadn't even considered! I like it, though. Testing the car at a variety of slopes might help determine consistency across the track. Definitely worth trying, I think.



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