Test track set up w / timers etc

[Doug-in-the-woods]

Either we got some fast cars or ??
Track is 42.5 ft from start gate to finish line. Start gate is 5.5 feet off the ground at a 45 degree angle, 6feet before it starts te curve which is 93 inches long. Aprox 29 feet of flat track.
Best time was 2.963. I have a hunch the track is just FAST not really the car.
Did see how an aggressive weight placement makes a real difference on the flat track.
The start tree works great as well as the electric start gates.
The track needs some work as I have slight bumps at the track joints ( cut the track w/ a circular saw and need to grind down the slight burs. Really upset the cars w/ aggressive weight placement (very light front ends.
One of my scouts has a car that worked great on the short track but w/ my "junk" car(having second thoughts on calling it junk) slightly outran him at the finish line. He would kick my butt on the short track.
Suggested building a new car with an aggressive weight placement.
Will post some pics later this week.

[GimpyPaw]

The fast times could have something to do with the fact that your start gate is about 18 inches higher than "normal" (If I recall a BestTrack start gate stands @ 4ft)

[Doug-in-the-woods]

That's what I kinda figured.
Will take a tape measure tomorrow and actually measure height of trak each foot so Stan Pope can figure out the acceleration in G's.
Saw a post of his calcs so now we can figure out correctly. I myself get lost with math.
Would be interesting to be able to announce at the race next weekend the numbers for acceleration of these little cars.
I still need to finish my c02 car.

[PWD]

Is this a commercial track? Or did some make the track? What is the track made out of? Wood? Aluminum? I believe you can somewhat compare times on commercial tracks. Easier to compare times on aluminum tracks. But you will see .10 differences even on the same type of track. For example, we have a 42' aluminum BestTrack and we have had cars record times .08 different than another 42' aluminum BestTrack. I assume it is because of track alignment.

You can't simple compare tracks based on height. Our cars will always run faster, about .14 of a second, on a longer Freedom track compared to a BestTrack. I believe the two tracks start gate are at the same height. In this case I think the difference is because the transition is different on the two tracks.

The other place you can see a big difference is the type of timer. Laser timers will cause cars to record much, much faster times. Often times more than .2 of a second than a magnetic switch. Microswitch timers will be about .03 faster than a magnetic switch.

[Stan Pope]

Will take a tape measure tomorrow and actually measure height of trak each foot so Stan Pope can figure out the acceleration in G's.

I think you misread my comments regarding who would do it.

I myself get lost with math.

It's for the kids ... learn! The "math" (and the physics, too) is high school stuff ... you can do it! You can even use a spreadsheet with one column per track increment to do the messier computations!

[Doug-in-the-woods]

Track is an aluminium track made by Beta. I mounted it betweenwooden frames.
The timers are made by Swantech utilizing a photodiode and Halogen light bulbs.
one per lane.
As for the math What are the formulas I need and hope I don't get lost.

[Stan Pope]

As for the math What are the formulas I need and hope I don't get lost.

Lessee ...
v = a * (t - t0) + v0
d = v * (t - t0) + d0
a = g * sin(slope)

a: acceleration, feet per second per second
g: acceleration of gravity, 32 feet per second per second
d: distance at end of interval, feet
d0: distance at start of interval, feet
t: time at end of interval, seconds
t0: time at start of interval, seconds
v: velocity at end of interval, feet per second
v0: velocity at start of interval, seconds
slope: determine from track interval measurements

You can separate the front and rear wheels as source of acceleration by looking at the weight distribution for that particular car orientation.