Calculate car speed.

Discussions on buying or building timers, solenoid start gates, light trees, weigh scales, and other race related electronics.
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SlartyBartFast
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Re: Calculate car speed.

Post by SlartyBartFast » Tue Dec 02, 2008 12:34 am

gpraceman wrote:I would expect
And thus the interest in data! Otherwise we just endlessly speculate. :P



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Re: Calculate car speed.

Post by SlartyBartFast » Tue Dec 02, 2008 12:38 am

NealOnWheels wrote:Two sensors placed a short distance apart could do the job and would be car length insensitive.
True. But, twice the holes, twice the hardware, more structure overhead...

Guess my only option is to test, test, test....

First I've got to test my pneumatic gate mechanism.

Have all the components sourced and priced. On to the next step.



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Re: Calculate car speed.

Post by msurebel » Thu Jan 19, 2012 9:08 am

If you could come up with a wireless lightweight tachmeter, you could measure rpms. Key would be how to make it wireless and light!



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Re: Calculate car speed.

Post by rpcarpe » Thu Jan 19, 2012 9:21 am

Isnt' the bottom line to make it better for the kids? Average speed and/or total time seems to get most kids pretty well invovled. I don't see a pay-off in a max speed sensor.


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Re: Calculate car speed.

Post by msurebel » Thu Jan 26, 2012 8:36 am

Definitely for the kids, it's just us engineer's curiosty wanting to know more. Heck, just the question had me curious about how to make a wireless speed sensor. LOL



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Duane
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Re: Calculate car speed.

Post by Duane » Thu Jan 26, 2012 9:28 am

NealOnWheels wrote:Two sensors placed a short distance apart could do the job and would be car length insensitive.

Place such a system at the finish line and you get the finish speed.

Place such a system at a point along the track where max speed is expected and you get an approximation of the max speed. On a typical track that point may be the transition from the slope to the flat.

Or do this at both points and use the data to determine the "lossiness" of a car.
Excellent!!



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Re: Calculate car speed.

Post by chromegsx » Thu Feb 07, 2013 2:38 pm

gpraceman wrote:
ohiofitter wrote:What about the hot wheels radar gun..........I know there cheap and they say they work.and you tube has a guy that dismantled one and made it bigger using house hold items..( I THINK) but you'd have to search for it.
A radar gun would give you a speed of a car at a certain point. I would wonder just how accurate a toy gun would be. You'd also need one for each lane.

Speed at a certain point(s) doesn't tell you who wins, so I don't really think it is a useful figure. One car could be slowing down more than an other, towards the finish, but not get nosed out before it crosses the finish. Looking at only speed at the finish would give a misleading result.
Old thread but wanted to provide input for any searchers out there. I have one of these radar guns. If your goal is to find a max speed on the track for one car on the track at a time (or the fastest car) they would work "ok" but would not likely give the resolution that is desirable to see if you are faster or slower than before. Also they have a bit high of drop out rate where it fails to pick up the speed of an object, which will cause frustration depending on intended use. This would not work for finish line measurements as the gun will only give you the max speed it measure within the radar "field". It will not allow you to pinpoint a spot on the track to measure. And for the most accurate measurement you would have to measure directly in front of the car travel path, or cut a slot in your guide rails at the bottom of your curve to measure from behind (not sure if this would work). You could still measure from the at a slight angle but to get a more accurate reading you'd have to do some trigonometry math work (cosines) to correct the reading to a more accurrate one. Most radar guns only read in whole mph anyway.

Of course this thread gave me a whole bunch of other ideas to try to collect useless data with a timer... I really gotta get off this forum. My list of ideas are growing faster than my time and money allow for. :(



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Re: Calculate car speed.

Post by knotthed » Thu Feb 07, 2013 6:41 pm

Would seem that one of these might be readily adapted to work?

Or you could incorporate something similar into your track with 2 sensors.



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Re: Calculate car speed.

Post by whodathunkit » Thu Feb 07, 2013 6:58 pm

Cool video knotthed!

Let's say that BB gun shot 600 feet per secound.

You can take the number of feet per secound and multiply that by 60,then the result by 60 again.
Then divde by 5280
Your 600*60(this is secounds, hence 600 feet per secound)=36.000*60
(This is the 60 minutes the amount of time in an hour)=2.160.000
(Feet in one hour)/5280
(Number of feet in a mile)=409.09

Stan, is my math right on this.. :idk: I could be off some what.
Last edited by whodathunkit on Thu Feb 07, 2013 9:22 pm, edited 1 time in total.


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Re: Calculate car speed.

Post by knotthed » Thu Feb 07, 2013 8:23 pm

Whoda,

Math looks good - label looks wrong - maybe it's just the formatting of the post.

600 FPS = 409 MPH (Miles Per Hour)



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Re: Calculate car speed.

Post by whodathunkit » Thu Feb 07, 2013 9:50 pm

Thanks.. knotthed,

I added BB gun to my formatting... Guess I missed that in the video. ;)

Whoda.


What type of automobile can be spelled the same forwards & backwards?

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Re: Calculate car speed.

Post by John Shreffler » Fri Feb 08, 2013 10:34 am

.... But, twice the holes, twice the hardware, more structure overhead...
Not exactly. It is twice the holes, and twice the sensors, but this is trivial because sensors are only ten cents apiece. If anyone is really serious about doing this final speed project, I will provide him absolutely free of charge a Transponder http://www.newdirections.ws/tr.htm. As long as the track is four lanes or under, the unused lane inputs go to a row of sensors two inches down hill from the finish line. Although you can do the calculations yourself from the display in Section 4 Hardware Setup, Randy should modify GPRM as an option, that automatically pairs up Lane 1 with Lane 5, subtracts, and divides by the appropriate constant to give the speed. Same with Lane 2 and 6, 3 and 7, 4 and 8. This figure could be displayed on the racing screen.

There is no structure overhead. Same light bulb is good for all the sensors.


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Re: Calculate car speed.

Post by gpraceman » Fri Feb 08, 2013 11:11 am

John Shreffler wrote:Although you can do the calculations yourself from the display in Section 4 Hardware Setup, Randy should modify GPRM as an option, that automatically pairs up Lane 1 with Lane 5, subtracts, and divides by the appropriate constant to give the speed. Same with Lane 2 and 6, 3 and 7, 4 and 8. This figure could be displayed on the racing screen.
I'd be hesitant to make such a change to the software, as there isn't much demand for that feature. The complexity that would be added to the software really isn't justified.

If you are trying to measure the speed of the cars, the finish line is where the cars are actually at their slowest. Might be better to see their speed just before the flat, when speed is at its highest.

Anyways, the speed that GPRM displays is the average scale speed from the start gate to the finish line. That really should be sufficient. Scale speed is just for the "Ooh and ahh" factor. It is not used for determining the standings (nor should it).


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Re: Calculate car speed.

Post by John Shreffler » Fri Feb 08, 2013 1:52 pm

Randy: I certainly agree that such a feature would have no place in the racing. But in this thread, I got the sense that the interest was to learn about performance during car construction and fine-tuning.

If you were to put it into GPRM, it would only be available to the Transponder because of the mechanical realities. It would have a hidden "switch" sort of like the Flight Simulator capability of Google Earth. Probably only one person in a hundred knows about Ctrl-Alt-A. It would not necessarily have to produce immediate profit. If mentioned at all, it would just be another feature to tout. The mathematical part of it is trivial, about 4 lines of code, although you would need another column on the display.

You never know what might catch on. I was watching the Henry Ford story on PBS the other night. People back then considered cars just a toy for the rich, but the thing would die out, and nothing would ever be as reliable as Dobbin.


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Re: Calculate car speed.

Post by gpraceman » Fri Feb 08, 2013 2:21 pm

John Shreffler wrote:Randy: I certainly agree that such a feature would have no place in the racing. But in this thread, I got the sense that the interest was to learn about performance during car construction and fine-tuning.

If you were to put it into GPRM, it would only be available to the Transponder because of the mechanical realities. It would have a hidden "switch" sort of like the Flight Simulator capability of Google Earth. Probably only one person in a hundred knows about Ctrl-Alt-A. It would not necessarily have to produce immediate profit. If mentioned at all, it would just be another feature to tout. The mathematical part of it is trivial, about 4 lines of code, although you would need another column on the display.
You really don't realize how much work that would involve, as well as the added complexity to the software. The more complex software gets, the easier it is for something to break.

With any change to the software, I have to look at the work required vs. the benefit. Right now, I only see a benefit to a very small number of users. If I get that request from many other people, then I would certainly consider adding in something of the sort.


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Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.

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