Speed variance in a single track over time

General topics of interest to racers and race coordinators alike.
Post Reply
User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 12:37 pm
Location: Bellevue, WA

Speed variance in a single track over time

Post by Noskills »

Hello all,

Simple question here. Our pack uses a track rented out by this very nice guy named Dave who runs the entire race. He has been renting his track to PWD races since 2007 and posts the fasted times in the track's history. (below).

I noted that all the top 50 fastest time are from 2007-08. Could one set up a track one way for a few years and get very fast times and later decide to set it up another way such that times drop? The top 50 times on this 42 ft Best track are 2.781 to 2.93. (My son has spot #54)

What other explanation could result in this finding? Maybe he only used his track for pro races in 2007-08 then switched to scouts? I doubt this as he only lists the scout times (e.g.. I am not on the board :oops: )
http://www.rentmytrack.com/FastestTimesAll.aspx

Just curious,

Noskills
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
User avatar
FatSebastian
Pine Head Legend
Pine Head Legend
Posts: 2807
Joined: Wed Jun 17, 2009 2:49 pm
Location: Boogerton, PA

Re: Speed variance in a single track over time

Post by FatSebastian »

Noskills wrote:What other explanation could result in this finding?
Maybe his starting gate sensor changed? A laser gate triggers the timer when the first car crosses and has the potential to produce lower times.

Maybe the track was shorter back then, or similarly, the finish line sensors were set farther up the track? Maybe the starting height was a little higher, so the cars picked up more speed in the flat?
BallBoy
Master Pine Head
Master Pine Head
Posts: 196
Joined: Sat Jan 08, 2011 8:46 pm
Location: SoJo, UT
Contact:

Re: Speed variance in a single track over time

Post by BallBoy »

I can see two plausible reasons for differing times, given the same track set up in the same room. First is the condition of the track. Graphite and other debris that isn't cleaned off the track from one race to the next could affect times. Second is the physical placement of the track. Floors, no matter how nice they look, are not level. So, a track placed on a floor, whether elevated or not, will not automatically be level. I suggest that unless the track was levelled side-to-side and start-to-finish with a precision laser level then the track is not identical from one setup to the next. I know that one of the tracks used for one of the racing leagues is in a permanent location (i.e. hasn't been broken down since the initial setup) and was set up using a laser level.
User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6856
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: Speed variance in a single track over time

Post by Stan Pope »

I vote for Ballboy's #2: "Second is the physical placement of the track. Floors, no matter how nice they look, are not level." For someone with a track set up, it would be interesting to see the effect of sliding a 1X4 under the stand by the starting line!

However, also consider that everyone knows that "almost everything was better back in the good ole days!" :)
Stan
"If it's not for the boys, it's for the birds!"
User avatar
birddog
Master Pine Head
Master Pine Head
Posts: 307
Joined: Thu Apr 26, 2012 12:40 pm
Location: Denver, CO

Re: Speed variance in a single track over time

Post by birddog »

Seth-

Our track times vary from year to year depending on how well we do the track setup. Are the connections tight, or are there gaps? Is everything clean and level? In terms of how a track is setup, for a 42' best track, I think you can account for time differences on the order of 0.050 seconds. In other words, the same car with one (poor) setup might run 3.01 and with a great track setup might be able to run 2.96. I don't think you'll see more than that due to track setup issues (for the most part).

Now, the times you are showing as "top 50" do not line up with standard Scout spec'd cars. I would expect the best standard Scout spec car to run a 2.95 (maybe a 2.94). Look at the times from the Mid-America race and you will see what I mean here.

So, that tells me the times were done using "pro" level cars built with all the special advantages they get (oil, razor wheels, bearings, etc).

I don't think you can compare those times as they just are not "apples to apples".

birddog
User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 12:37 pm
Location: Bellevue, WA

Re: Speed variance in a single track over time

Post by Noskills »

Thanks all. My curiosity is up so I am going to ask the track owner. I actually like FS's idea of some sort of hardware change after 2008. That would explain the consistent fast times prior to 2008. I would think if it was floor or track issues that at some time between 2008 and 2014 there would be some floor or track set ups as advantageous as the ones from 2007-2008 and the top 50 would have more representation from the last 6 years.

Of note I did experience some local variation last year where my son ran a 2.963 at the pack and a 2.992 at regional (same track) difference spot. (of course I am sure some will note the decrease cold have been due to car issues after 7-8 runs at the pack level)

Thanks again,

Noskills
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 12:37 pm
Location: Bellevue, WA

Re: Speed variance in a single track over time

Post by Noskills »

FS was correct! Mystery solved!

Here is what the track owner said:

"Yes, the track setup was different, prior to 2008, we had a laser start instead of a switch.

The laser trip and start the timer for all 4 lanes.

We found that to be less accurate because a heavy car would trip it and then the faster car with good alignment, etc, would get a slower time because the heavy car tripped the laser.

The laser sat about 5 inches in front of the start pegs, and so the cars were already moving when they started the timer."
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
Post Reply