Gravity Vehicle C

[chalker7]

Another thing to consider regarding the maximum distance ideas being floated around is that it would make timing incredibly difficult. Currently, there is (normally) a pretty distinct stop (the vehicle brakes and rapidly decelerates) that helps cue timers as to when to stop. With the gradual decelerations that might result from a maximum distance effort, it could be a bit hard to tell exactly when the vehicle "stops." This problem would only get worse for the higher end teams who will presumably have softer decelerations.

[Balsa Man]

A bit of a....kinda fundamental missing of issue here; at least in the context of the suggestion I raised.
I was suggesting, and pointing out the value of, using max distance INSTEAD of time to measure the "speed factor."
As I explained, measuring time to a target distance, and how far a vehicle will roll w/o braking, both measure the same thing- the two things that go into "speed"; 1) how much energy you get off the ramp, and 2) how well you minimize the friction/rolling resistance losses of that initial energy.

The case I tried to make, and obviously didn't clearly enough, is the reliability/precision of those two approaches to measuring the same performance aspects. My sugggestion was to use max distance measurement as a replacement to timing, and then to do precision(to a target point) just like it was done this year.

As I described, we found that significant differences in mass management and friction management between our two teams' vehicles only produced a 0.2 to 0.4 second difference in time (at 5m and at 10m). With a total run time to 10m under 4 sec, a 10% difference, and with the difference getting into the human error range of timing accuracy. However, when we let both run as far as they would go, we had one at 20m, and one at 30m - a 50% difference, and more importantly, a very easily, accurately/precisely measureable - and BIG difference. Takes the human error on timing completely out of the equation.
That led to discussion of having enough room to go that far was an issue for tournament organizers, that led to the suggestion of limiting ramp height and weight to limit max roll capability. I understand that needing and getting 20m venues may be an insurmountable problem. I also understand that time measurement for speed is, and will be a wild card that distance measurement would totally eliminate.

[Jdogg]

The top teams will then have cars that travel the whole length of the gym. Our car will not travel more than 15m because of a brake mechanism on the car that can only be set to 15m at the max distance, but at around 14m it is still traveling at just about the same speed that it came off the ramp at. Our car losses almost no kinetic energy due to thermal energy, having relatively no friction on the axels. I'd say that all the top teams, the teams that your idea would try to distinguish between, would require areas bigger than a airplane hanger... I really think that although there is a very small difference between the fastest cars, there is still a distinguishable accuracy measurement between teams. This accuracy once achieving a fast car is the goal of all teams, I believe that's why accuracy is the goal for most teams, after building a relatively fast and consistent car.

[illusionist]

To limit the max distances that cars like yours and Balsaman's can travel, the rules can just set a max weight <2.5kg and restrict ramp height. I'm sure that a .5m tall ramp and a .5kg car will travel less than 20m (I have no evidence of this though).

[Balsa Man]

As illusionist notes, and I said in my last message, and 3 or 4 times before that, obviously, with current ramp height and mass specs, space is a problem; both mass and height would have to be down.

However, as to needing a hanger, bolgna (that's polite for baloney). Ours is moving very briskly at 10 m, like you see with yours. It is very low friction. I'm pretty darn certain you could not get to 40m. Cut h and m in half, you're inside 20m

The problem I was throwing around ideas about was for vehicles that are both fast and accurate; if they're within a few tenths of a second, and getting inside 5cm, imprecise timing can and will lead to "incorrect" scoring/ranking. That's just how it is

[Jdogg]

you'd be surprised, frankly if you have relatively no friction on the axles, the car should be able to travel for forever. Although that isn't possibly, i still believe that even with a .5m high ramp, some cars at nats. will have the ability to travel over 25m. It just matters how much friction their is in your axles, say someone used super-pulley's, they spin for about 3min's on a good spin. The amount of friction loss would be close to negligible, making almost any gravity vehicle have the capability to travel 20m or so. But i haven't experimented with super-pulley's, but i know that if you roll a ball down a ramp, the ball will roll until it hits a wall (very long distance's). This makes me believe that some teams will definitely be able to hit greater than 20m with a car that weighs under 100g and is released down a .25m high ramp. And it's not baloney, we could definitely hit over 40m with our old car (assuming that it didn't run into a wall), it was still going fairly fast at 20m, fast enough that i'd say it might have lost less than .2m/s over that 20m distance.

[illusionist]

If the team that could travel the furthest distance would win, this event would become about who could buy the best bearings. There are skateboard bearings that cost hundreds of dollars, and of course they perform like they're worth hundreds of dollars. Teams that have to use cheaper bearings due to budget restraints will obviously be at a disadvantage since winning the event will basically come down to having the least friction.

Since there is a limited distance this year (max 10m), the amount of friction your axles have does not make a significant difference in your score. After a certain point, the times will become too close to differentiate (our whole argument).

Should next year's rules go with the furthest-distance-method of measuring, the team that can buy the best bearings will win (assuming that all vehicles are decently accurate).

[chalker7]

you'd be surprised, frankly if you have relatively no friction on the axles, the car should be able to travel for forever. Although that isn't possibly, i still believe that even with a .5m high ramp, some cars at nats. will have the ability to travel over 25m.

This is the fundamental problem. By removing any limits on distance, we simply do not know how far the best teams in the country will be able to go. While the cars this year might be able to travel ~20m, distance wasn't the goal for teams. If they were actively shooting for going as far as possible, most tournaments would be unable to find a room long enough to house the event. While it's definitely an interesting idea (and I apologize for being confused about the timing issue as currently laid out,) it's simply unfeasible for logistical purposes (another that we haven't mentioned is that measuring to the mm gets more difficult the further we reach, I wouldn't want to force supervisors/directors to purchase multi-hundred dollar measuring tools on top of everything.)

All that being said, I think we'll definitely be able to refine the rules for next year such that they provide a new twist on the challenge while still making the event approachable to new teams and able to be run at the majority of competition venues.

[AlterNSO]

A member of my team made a suggestion that I thought might be reasonable for next year.

1.Have longer times be better scores. (This should make human error a smaller percentage of the overall time. It would also change the event quite a bit because ideally the car shouldn’t use a breaking system at all.)

2.Have timing stop once the car reaches the fixed point on the track. (I think this should be easier to time instead of looking for the point the car stops.)

3.If the car does not reach the fixed point it receives a time score of 0. (This would mean it would require some risk to go for a really good distance score.)

This would also force teams to change their ramp designs from last year and likely make the ramps adjustable at the competition to do well. This might to easy or have some other issue I’m not considering but I think it might be an interesting alternative and would require a lot of testing because of the lack of a breaking system.

[nejanimb]

you'd be surprised, frankly if you have relatively no friction on the axles, the car should be able to travel for forever. Although that isn't possibly, i still believe that even with a .5m high ramp, some cars at nats. will have the ability to travel over 25m.

This is the fundamental problem. By removing any limits on distance, we simply do not know how far the best teams in the country will be able to go. While the cars this year might be able to travel ~20m, distance wasn't the goal for teams. If they were actively shooting for going as far as possible, most tournaments would be unable to find a room long enough to house the event. While it's definitely an interesting idea (and I apologize for being confused about the timing issue as currently laid out,) it's simply unfeasible for logistical purposes (another that we haven't mentioned is that measuring to the mm gets more difficult the further we reach, I wouldn't want to force supervisors/directors to purchase multi-hundred dollar measuring tools on top of everything.)

All that being said, I think we'll definitely be able to refine the rules for next year such that they provide a new twist on the challenge while still making the event approachable to new teams and able to be run at the majority of competition venues.

This is how it went with Trebuchet too, seems to me (still one of the best SO events ever, imho). Most of the time, it was okay and you'd have a pretty good idea of how far teams could throw, but then at the very top you'd get a team (read: Penncrest) that had a treb so much better than the norm it was launching ridiculous distances. At least in that case you can just have the event outside and you don't need a level track, but I'd guess its a mistake to underestimate the ability of teams to do crazy things (like the weight score of mission possible from a couple years ago, etc.). That's at least part of why there's a maximum load for the balsa events (no running out of weight to add), etc.

Video timing for nationals does not seem all that absurd. Not that much of an expense to set up, and you'd only need to reference it (the time issue) when times/scores were very close. Maybe not necessary for every competition, but for nationals it seems like a good idea.