Track length question

Mar 19, 2015
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I was at my son's pinewood derby today. I asked one of the scoutmasters how long the track was and he didn't know. I meant to ask the guy running the computer program but then I forgot. My wife took a picture of a friend while they happened to be by the projector screen showing the. heats. One of the times on there was 3.0877 =198.7 mph. Can anyone tell me what the track length is based on that info?
 
The honest answer is, "It depends." The software needs to have the track length input into the settings, in order to be able to calculate scale MPH based on the time. If this value is incorrect, then the MPH isn't going to match what some other track might show.
 
Ok thanks guys, I was assuming it was 42 feet until I watched some of the video of the amateur race on here and there was still quite a bit of difference in the mph in a couple times that I saw that were close to that. Maybe its the way the program was set up. I'm pretty sure it was a Best Track
 
The mph is based on what you tell the race manager for length. A lot of scout packs may just put in 42ft when it is really like 39 something from start pin to finish sensor.
 
robo4881 said:
I was at my son's pinewood derby today. I asked one of the scoutmasters how long the track was and he didn't know. I meant to ask the guy running the computer program but then I forgot. My wife took a picture of a friend while they happened to be by the projector screen showing the. heats. One of the times on there was 3.0877 =198.7 mph. Can anyone tell me what the track length is based on that info?

What formula is used to convert finish time in seconds to mph. It must include track length but how is the calculation done? For example what is the mph for my car on my 39 foot track for a pin to timer of 2.8500 seconds?
 
Mr Chips Racing said:
Am I incorrect in stating that the MPH for PWD is only for fun? MPH are MPH speed doesn't scale.

Yeah, this is my perception as well. I mean, it is a proportional number, so it can give you an idea of how fast your car was moving in comparison to the other cars on the track...but that's it. It means nothing in comparison to "speed" on a different track, since there's no way to know how the numbers were input into the race manager.
 
Mr Chips Racing said:
Am I incorrect in stating that the MPH for PWD is only for fun? MPH are MPH speed doesn't scale.

Speed does scale because you are scaling the distance at 1/25
The thing to remember here is that TIME is constant, that does not scale.
If you take 36 feet for the distance of the track and multiple by 25 you get 900 feet. Divide that by 5280 and you get .1705 miles. If you were to cover that distance in 3.0877 seconds, you get 198.7 MPH.
For what its worth, I am not a fan of displaying scale speeds, but the kids do like it.
It almost never fails that someone will come up to me and ask if the cars are really doing 200 mph. I love the look on their face when I tell them its more like 9. LOL
 
The MPH is largely for fun, but is an accurate portrayal of scale distance over time. A few years back, when my son was racing at Districts, some other people in the stands exclaimed, "300 MPH?! Wow!" during one of the runs. At the time, I blew it off, as I'm looking only at times. A few seconds later, I realized that the timer had glitched and gave times on that round of a full second lower than any other time. It took some doing to get them to admit the error and not include that time.
 
zeebzob said:
Mr Chips Racing said:
Am I incorrect in stating that the MPH for PWD is only for fun? MPH are MPH speed doesn't scale.

Speed does scale because you are scaling the distance at 1/25
The thing to remember here is that TIME is constant, that does not scale.
If you take 36 feet for the distance of the track and multiple by 25 you get 900 feet. Divide that by 5280 and you get .1705 miles. If you were to cover that distance in 3.0877 seconds, you get 198.7 MPH.
For what its worth, I am not a fan of displaying scale speeds, but the kids do like it.
It almost never fails that someone will come up to me and ask if the cars are really doing 200 mph. I love the look on their face when I tell them its more like 9. LOL

Well - thanks, that is the answer I was looking for! You guys are right - it doesn't really mean much, I just rely on the race time in seconds as meaningful. Was just curious about the MPH number.