Gravity Vehicle C

[twototwenty]

Did you see lots of really long cars, like there were at my states? I think that idea is clever, if not particullarly hard to come up with, but, once again, the advantage it gives is eaily lost in timing innacuracy.

[bearasauras]

I'm sorry to hear that. How bad was the timing? Did they have 3 timers, then taking the median?

[illusionist]

Most of the vehicles seemed to be about 40cm long. There were a few really short ones (which performed poorly), but none that i saw that were really long.

Bear- They had 3 timers, although I'm not sure if they took the median or the average of the three.

[bearasauras]

Were they using the excel scoresheet from the National web site? If they are and they're putting in all 3 times, it'll take the median automatically, and hopefully that'll make timer errors less of an issue.

[illusionist]

Were they using the excel scoresheet from the National web site? If they are and they're putting in all 3 times, it'll take the median automatically, and hopefully that'll make timer errors less of an issue.

Sorry bear, I wasn't able to get a good look at the supervisor's computer. However, he was using an excel sheet, though I don't know if it was the Nationals one.

By the way, our vehicle was made of plastic K'nex toy parts and CD wheels. It's able to get to 10m in 4.7 seconds and is quite accurate. The team that got 4th at Michigan states also used K'nex and CDs. Just goes to show that you don't need a complex or expensive device to perform well.

[Balsa Man]

Sorry to hear you ran into problems at State, Illusionist.
On very long vehicles, long is good, but only to a certain extent. Having length greater than width does improve linear stability. But going really long gets you into a negative tradeoff. Remember, the energy you get from the ramp is determined by how far the center of mass falls. If you have (we had one at State) a vehicle the length of the ramp, then the center of mass is halfway down the ramp, which means a lot less v coming off the ramp. You can help that by putting a chunk of mass to the rear, but if you get it too far back, the load on the front wheels gets light enough it wanders.....

Fleet, appreciate the historical perspective on tournament organizers having problems with space for vehicle-based events; maybe, as I said when I first brought up the idea of total distance as a much more precise way to measure the "speed factors" (energy in, and friction management), it may well be an insurmountable obstacle. I just hate seeing/having a wildcard factor in an event.

[illusionist]

So after talking to a few other teams from states, it appears that our vehicle was not the only one that curved so much. There were two tracks set up, and I've been told that the floor of the track we ran on was tilted. The 4th place team had to place their ramp all the way to the right of the starting box in order to have their vehicle curve to the middle (their vehicle also did not ever curve in practice). So it ended up being a lot about luck.
Just a word of caution for anyone else, even though this kind of thing should be pretty rare.

[Balsa Man]

So after talking to a few other teams from states, it appears that our vehicle was not the only one that curved so much. There were two tracks set up, and I've been told that the floor of the track we ran on was tilted. The 4th place team had to place their ramp all the way to the right of the starting box in order to have their vehicle curve to the middle (their vehicle also did not ever curve in practice). So it ended up being a lot about luck.
Just a word of caution for anyone else, even though this kind of thing should be pretty rare.

I'm really sorry to hear that; it's a darn shame, and much more than just a wild card. The fact that small but real differences in speed get lost in the inevitable error bars of human timing is just a random wild card that the uppper end teams have in play. But what you describe is a real "level playing field' issue; those teams that chose to, or were assigned to use the slanted track were put at a profound disadvantage. Obviously nothing to be done at this point- its done, and I'm certain that creating an unfair advantage/disadvantage situation was totally unintentional, and not even within the awareness of the folk running the event. Having analyzed the variables at play in performance/scoring, this possibility never ocurred to me. At both Regionals and State, there was only one course.

I would hope at Nationals, the potential for this sort fundamental unfairness would be avoided by using a single track- same playing field for all, level or not.
Thanks for putting it on the radar screen.
If two tracks are required to meet schedule imperatives (which could be the case), I would hope everything reasonably possible would be done to .....make things fair and equal. Have to think about the details of what that might/could involve; I suspect that the amount of non-levelness that could cause significant curving would be less than what one would see in a standard bubble level. There are professional carpenter levels with a digital readout, that show you millimeters out over like a meter, maybe 4 ft- one of the coaches for towers for another team at Regionals/State made such a critter available for checking the levelness of the tower test stands (a similar 'level playing field" issue when running two test stands). Nationals folk might want to chase such a tool down, if they already haven't. The only other thought would be getting ahold of a test vehicle, and seeing if it runs.....comparably on both tracks....

[wlsguy]

Ideas for next year....

How about making the distance score something like the ratio of distance travelled vs the height of the ramp?
This would then be added to the typical prediction score and time.

It would be more about making a truely efficient machine with respect to concervation of energy, speed, etc.
It might also encourage teams to use smaller venues (and eliminate the issues with lane lengths)

Just an idea.

[twototwenty]

I don't know about using that ratio...it would be essentially the same thing as the distance-focussed competition which has already been discussed and the flaws of which have already een pointed out, only factoring ramp height in, but that wouldn't make much of a difference, as competitors would only need to run a few calculations to find the optimal height.