Gravity Vehicle C

[illusionist]

H-B-P,
You asked about time.
Posted at 10m on the previous page ("under 4").
At 5m, just under 1.9. I was pleasantly surprised how little speed is getting lost from 5 to 10

I think he just likes bragging

Ours is about 4 seconds for 8 meters, hoping to decrease that with the new vehicle and wheel design.

[Balsa Man]

Sure, who doesn't?
Seriously, I was truely impressed and a bit surprised how well the team implemented the lengthy discussions and brainstorming we had on how important friction management was, and what things could be done to minimize it and maximize speed off the ramp, and how to do that. I've shared most of that here; more details a bit later in the season, of course.
Your time is, btw, quite respectable! Hopefully you've picked up some clues that will help improving it.

[illusionist]

Thanks, and roughly how much difference in time can I expect by going from tires like these (http://gallery.scioly.org/details.php?image_id=1296 the two smaller ones on the front) to wheels similar to the ones you described, on a 0.5-1.0 kg vehicle?

[Balsa Man]

Thanks, and roughly how much difference in time can I expect by going from tires like these (http://gallery.scioly.org/details.php?image_id=1296 the two smaller ones on the front) to wheels similar to the ones you described, on a 0.5-1.0 kg vehicle?

No data basis to say....
I've felt wheels like those; lots flex/deformation. Significant improvement.
Also no data to understand behavior at light vehicle weight; we've run near max mass from the start
So, a guess, and a wild one at that, assuming you're running good bearings, at least half a second to 10m, conceivably approaching 1 sec. I'll be curious to find out, do let me know.

[Half-Blood-Princess]

@Balsa Man: Wow that is super fast!!! I think we got that once.... OMG regional is on march 3rd for us, we're so not ready DX ugh haha

[Balsa Man]

The 3rd for us, too.
I really tried this year to push the kids to get things done and into practice and fine-tuning mode before Regionals were on top of us, but, once again, we're in serious crunch mode. Same guys doing GV are doing Robot Arm, so GV will be running with a lot less brake system calibration than we'd like. Speed and consistent straight running are great; a good handle on time vs distance; its just that last variable that's not really nailed down yet....
Good luck; hopefully we'll see you at State.

[Half-Blood-Princess]

Oh yeah! I just looked over at your profile and saw you're at Fort Collins, we always go to State btw haha

[Balsa Man]

We have, too (for longer than the 12 years I've been involved). Just don't like counting chickens before they hatch....

[Half-Blood-Princess]

Very true, but our B team has never got lower then 4th place at regionals....

[fishman100]

Here's something that SJ posted a while back:

On another note, I was thinking about whether a long car or a short car would be better, and while getting the longer car to go straight is easier, a shorter car can have a higher center of mass. My basis for these assertions are that if the mass of the wheels at either end are m and we add an additional 3m on the back wheels then the center of mass shifts back to 4/5 L. Therefore the CM for a 1meter car is 20 cm from the back while it is only 10cm for a 50 cm car.

How does having a longer car allow the vehicle to travel straighter than a shorter car?