Gravity Vehicle C

chalker7
Member
Member
Posts: 610
Joined: Tue Sep 28, 2010 12:31 am
Division: Grad
State: CA
Contact:

Re: Gravity Vehicle C

Postby chalker7 » Fri Apr 27, 2012 3:52 pm

calcarbon wrote:
Balsa Man wrote:Understand and do appreciate the sufficient space issue, and it may, in the bigger/national perspective, be an insurmountable barrier. On the other hand, the ~12m practical limit you note seems ....pretty conservative.
Did a quick check on basketball court dimensions:

Regulation Sizes- Official Measurements:
Court Size Overall:
•NBA and College – 94 feet long and 50 feet wide
•High School – 84 feet long and 50 feet wide
•Junior High – 74 feet long and 42 feet wide


Many regionals (and even state tournaments) do not necessarily have access to a basketball court, in fact many resort to running the vehicle events in hallways.


Sorry...accidentally posted under my account from High School up there (don't know why my computer logged me in as that).... The point remains, a basketball court is not a given.
National event supervisor - Wright Stuff, Helicopters

Balsa Man
Coach
Coach
Posts: 1318
Joined: Thu Nov 13, 2008 11:01 am
Division: C
State: CO
Location: Fort Collins, CO
Contact:

Re: Gravity Vehicle C

Postby Balsa Man » Fri Apr 27, 2012 6:37 pm

chalker7 wrote:
calcarbon wrote:
Balsa Man wrote:Understand and do appreciate the sufficient space issue, and it may, in the bigger/national perspective, be an insurmountable barrier. On the other hand, the ~12m practical limit you note seems ....pretty conservative.
Did a quick check on basketball court dimensions:

Regulation Sizes- Official Measurements:
Court Size Overall:
•NBA and College – 94 feet long and 50 feet wide
•High School – 84 feet long and 50 feet wide
•Junior High – 74 feet long and 42 feet wide


Many regionals (and even state tournaments) do not necessarily have access to a basketball court, in fact many resort to running the vehicle events in hallways.


Sorry...accidentally posted under my account from High School up there (don't know why my computer logged me in as that).... The point remains, a basketball court is not a given.


Just in the context of discourse; not trying to argue, beat a dead horse, etc., and with all due respect for the problem of establishing venue parameters that can work for everyone - :)

What got me going down this path is having realized how the way it is this year disproportionately impacts the “good” vehicles; the ones that run pretty fast, and pretty straight. Among this “upper end”, things (design, build) where a team has done a little better – a little more v, a little less rolling friction, get lost in the human timing error bars; they’re not correctly/precisely scored or ranked; inside the upper range of performance, it’s just a dice roll. That’s inherently unfair.

When there is a way to precisely and reliably measure/score/rank those performance improvements that a team may put a lot of effort into producing, it needs to be given serious consideration. The “winning differences” in speed that can be engineered above a certain level are small, but real; they can’t be reliably measured by a start to stop time measurement; they can by a max roll measurement.

Understand that some venues don’t have a gym option. So what would be the impact- the effect on the event, and scoring ranking – if a tournament didn’t have a gym, and had to go with a hallway to get a 25m track?
The “good” vehicles are not going to have a problem “staying off the walls”, and they would get the precise/reliable (and correct) scoring/ranking that measuring max distance capability gets you. The more linearly challenged vehicles would get ranked in appropriate order for how they deal with the challenge of making it roll straight. No unfairness, and elimination of the current wild card factor. Rules could specify min length and width; as noted before, weight and ramp height could limit length to something every venue could come up with…..

twototwenty wrote:Balsaman, I like your idea for the change in the competition you mentioned, but as I understand it, if the team's car were to not go straight the first time in the max distance run, they would then have to try to make thier vehicle not go straight in thier next 2 runs, which seems to me to be a counterintuitive way of measuring accuracy. Just a thought, though: otherwise, I really like that idea.
On an unrelated note, how is it that your get your car's wheels to be in the perfect rectangle necessary for an accurate run?


No, my thought on giving teams the option, and challenge, of placing "their" target point on/along the distance line following their max distance run is this. If they've tested enough to know their car consistently runs a line (i.e., if you don't adjust the ramp and/or alignment of car on ramp, it'll run the same line), then they'd put their mark where it crossed the distance line, and know their left/right error on their first distance precision run was going to be pretty close, and the challenge would be setting the braking distance, and then in the second distance precision run, further refining braking distance, and possibly minor L/R clip placement. If it "did not go straight" in the first (max dist) run, they'd have to decide, did something "go wrong" (that they can eliminate in the distance precision run(s), in which case they'd put 'their target mark' where they think it will go - and then see how precisely they can dial it in to that marl in their two distance precision runs.

On wheel alignment precision, it is a pretty simple "how do you build with precision" problem. Step 1 is precise measurement, step 2 is building to your precise measurements. Get parallel sides on your chassis plate; get axle lines perpendicular to the sides. Make a guaging/measuring bar for the distance between axles; align the axles so on each side, the distance between axles is the same; you can do that pretty easily to a thousandth of an inch or so. A number of ways to build simple jig(s) to get precise alignment, too. There is also the option of building in adjustment capability. We put our front axle on in good alignment with an axle line perpendicular to the sides. We established a rear axle line parallel with the front axle. We mounted the bearing carrier for one side of the rear on the rear axle line. On the other side, we put in a screw-adjustable bearing carrier, centered at the line. Has about 1/16th" room either side of center; so you make runs, and adjust the screws till it runs straight.
Len Joeris
Fort Collins, CO

fleet130
Staff Emeritus
Staff Emeritus
Posts: 433
Joined: Sat Nov 10, 2001 11:06 pm
State: -
Location: Mare Tranquillitatis
Contact:

Re: Gravity Vehicle C

Postby fleet130 » Sat Apr 28, 2012 5:51 pm

In the original "wheeled vehicle" event (Mousetrap Vehicle), the object was for the vehicle to go as far as possible. In a few years, vehicles were capable of traveling significantly farther than the length of a gymnasium (a few more than twice the length the length). The goal was changed to a fixed distance (20 meters) so the event could be run in most gymnasiums. There were still complaints that sites were unable to accommodate this distance, so it was reduced to 12 meters. Even at 12 meters, there were complaints that the distance was too far for sites to accommodate. The distance was reduced to 10 meters where it has remained (for the most part). While those complaints may/may not be valid today, there would probably be resistance to increasing the distance. In any case, discussion is good and suggestions are always welcome!
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!

User avatar
fishman100
Exalted Member
Exalted Member
Posts: 478
Joined: Fri Jan 28, 2011 9:26 pm
Division: Grad
State: VA
Contact:

Re: Gravity Vehicle C

Postby fishman100 » Sat Apr 28, 2012 7:00 pm

A belated congratulations to Balsa Man, your vehicle and ramp looks great!

What if next year, the size of the Launch Area could be increased to a 200cm x 75cm rectangle, and the target point can be placed at any distance from 5-10 m (in different intervals depending on the tournament) and anywhere along the 200 cm of the track, not just along the center line of the Launch Area?
Langley HS Science Olympiad '15

User avatar
illusionist
Member
Member
Posts: 942
Joined: Sat Mar 20, 2010 11:13 pm
Division: C
State: MI
Contact:

Re: Gravity Vehicle C

Postby illusionist » Sun Apr 29, 2012 7:27 pm

States went very, very badly. Not sure why, but our vehicle (which was off by 1.8cm from the target point when measured as a point to line distance, parallel to the track) curved so that it wound up about 20cm to the left of the target point.

Overall though, I was surprised at how competitive this event was. Relating to what BalsaMan said about the timers, my friend's team missed the sixth place medal due to the lack of the timers' accuracy. In terms of vehicle design though, I didn't see any really clever designs like BalsaMan's team's.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: Thu Mar 24, 2011 5:28 pm
Division: Grad
State: NY
Contact:

Re: Gravity Vehicle C

Postby twototwenty » Sun Apr 29, 2012 9:48 pm

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
Member
Member
Posts: 315
Joined: Wed Mar 05, 2003 4:33 am
State: CA
Location: Los Angeles, California
Contact:

Re: Gravity Vehicle C

Postby bearasauras » Sun Apr 29, 2012 10:14 pm

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

User avatar
illusionist
Member
Member
Posts: 942
Joined: Sat Mar 20, 2010 11:13 pm
Division: C
State: MI
Contact:

Re: Gravity Vehicle C

Postby illusionist » Sun Apr 29, 2012 11:03 pm

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.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

bearasauras
Member
Member
Posts: 315
Joined: Wed Mar 05, 2003 4:33 am
State: CA
Location: Los Angeles, California
Contact:

Re: Gravity Vehicle C

Postby bearasauras » Sun Apr 29, 2012 11:45 pm

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.

User avatar
illusionist
Member
Member
Posts: 942
Joined: Sat Mar 20, 2010 11:13 pm
Division: C
State: MI
Contact:

Re: Gravity Vehicle C

Postby illusionist » Mon Apr 30, 2012 1:05 am

bearasauras wrote: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.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

Balsa Man
Coach
Coach
Posts: 1318
Joined: Thu Nov 13, 2008 11:01 am
Division: C
State: CO
Location: Fort Collins, CO
Contact:

Re: Gravity Vehicle C

Postby Balsa Man » Mon Apr 30, 2012 12:51 pm

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.
Len Joeris
Fort Collins, CO

User avatar
illusionist
Member
Member
Posts: 942
Joined: Sat Mar 20, 2010 11:13 pm
Division: C
State: MI
Contact:

Re: Gravity Vehicle C

Postby illusionist » Tue May 01, 2012 11:44 pm

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. :roll:
Just a word of caution for anyone else, even though this kind of thing should be pretty rare.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

Balsa Man
Coach
Coach
Posts: 1318
Joined: Thu Nov 13, 2008 11:01 am
Division: C
State: CO
Location: Fort Collins, CO
Contact:

Re: Gravity Vehicle C

Postby Balsa Man » Wed May 02, 2012 1:46 pm

illusionist wrote: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. :roll:
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....
Len Joeris
Fort Collins, CO

wlsguy
Exalted Member
Exalted Member
Posts: 364
Joined: Mon Mar 23, 2009 4:08 pm
Division: Grad
State: OH
Location: Ohio
Contact:

Re: Gravity Vehicle C

Postby wlsguy » Wed May 02, 2012 6:52 pm

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
Exalted Member
Exalted Member
Posts: 292
Joined: Thu Mar 24, 2011 5:28 pm
Division: Grad
State: NY
Contact:

Re: Gravity Vehicle C

Postby twototwenty » Wed May 02, 2012 7:10 pm

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.


Return to “2012 Build Events”

Who is online

Users browsing this forum: No registered users and 1 guest