Gravity Vehicle C

[GoldenKnight1]

I either remake my car less wide, or make it decellerate more gradually..increasing my time score
haha...my car has 2mm clearnace between the nails on my ramp....

Lets say you increase your run time by a tenth of a second by making the breaking process at the end take this additional time. This would cause a significantly smaller force than is needed in the original sudden breaking. If it originally took a tenth of a second to stop this additional tenth of a second will decrease the force on the car by half. Yes this tenth of a second will hurt your time score by 2.5 points but if this gets you closer by more than 2.5mm that overall with help your score. 2.5mm is less than the thickness of two dimes.

[Balsa Man]

I either remake my car less wide, or make it decellerate more gradually..increasing my time score
haha...my car has 2mm clearnace between the nails on my ramp....

Lets say you increase your run time by a tenth of a second by making the breaking process at the end take this additional time. This would cause a significantly smaller force than is needed in the original sudden breaking. If it originally took a tenth of a second to stop this additional tenth of a second will decrease the force on the car by half. Yes this tenth of a second will hurt your time score by 2.5 points but if this gets you closer by more than 2.5mm that overall with help your score. 2.5mm is less than the thickness of two dimes.

Right on. Figuring out and understanding how the scoring factors work- together, and optimizing what matters most/scores most is critical. The time penalty of progressive braking is very small.

Doing the video analysis to figure out what's going is a VERY nice piece of work- well done!
The thing that struck me- and may be of help- 1/4" stainless flexing tortionally. What ramp height are you using? I could be wrong, but it sounds like you're running pretty fast- like the kind of speed from last year's 1m ramp height....

The ramp height scoring factor introduced this year is BIG. If you work up a spreadsheet looking at points for time and ramp height, with a range of ramp heights, it becomes clear you want a much lower ramp height. Optimal height will depend on ....the combined frictional characteristics of your vehicle. At any given distance, as you take ramp height down, score (time + ramp height factor) decreases, and then it starts to go back up. At different run distances, that optimal ramp height is different- not a lot, but it is different. For our vehicles, it looks like 38-40cm is optimal

So, if you are running at 1m, reducing ramp height will help you a bunch- significantly less speed, less braking forces to manage. If you've already factored this in, then spreading out the time over which braking happens is the path to solution. Doing that with something elastic may be part of the rebound effect you're seeing. If, on further analysis seems to be the case, inserting a crushable.....thing/element might help - ?balsa, styrofoam- something like that. Just a thought...

[_HenryHscioly_]

I've been testing by pushing the car.....havent used it with my ramp .. ._.
I'm pushng at about last year's speed....so maybe it wont even be a problem once I find my optimum height, and speed is lower..
haha...all my worrying, possibly wont be useful until its actually done(i always end up usng all my tme thnking, instead of actually physically do somethng..)

Mmy ramp is quite unbalance
The right side of it, where it meets the floor, has a .5cm gap.
Last year, I had the same problem, but because there was a lot of room underneath the ramp, just stuck couple lifting weights and that made it even
However, my ramp now is about 40cm deep so not to much room to stick heavy weights to weigh the ramp down.
Rule 3g allows to hold the ramp for it to not move....what's your opinion, of I push down on the top of the ramp(to make the front edge of ramp flush with the floor)?

Even with ramp surface pushed down to touch the floor, there is a 1.5mm gap because of the thickness of wood I used for the ramp surface. I already sanded it a bit from 1/8", but I was afraid the wood might break/chip if i get it too thin.
My wheel diameter is 7cm. Will the 1.5mm gap make my vehicle lose significant energy?
I was thinking of adding a piece of construction paper over the gap, since paper would result in less than 1.5mm gap.

[Balsa Man]

The issue with the gap/jump at the toe of the ramp is not about energy, it's about consistency. Absolutely critical for good scoring. You need to be able to run the same line, run after run- the only way you can (accurately) make an adjustment on the second run that will get you a good distance score. With an uneven edge, moving the ramp to push/hold the front edge down, or flying off a jump (especially w/ the wheel wobble you mentioned)- like rolling dice....

If you make 3 runs in a row to 10m, how close together are they? Not talking about braking distance, talking about linear precision. With a good stiff chassis, and good build precision (ramp and vehicle), I can tell you that it can be done to within a bit over a centimeter. It doesn't do you much good to get braking precise to, say, a couple centimeters, if it wanders side by, say 7, or 8, or 10cm

[KingofTheCoaster]

Hey I just had a quick question about an idea that I had. Do you think that it would be legal to attach some sort of string to my ramp, and then wind it up on the back of our vehicle? To get the target distance, all that we would have to do is adjust the length of the string. I don't believe that there's any rule against it as long as the string does not touch the floor.

[iwonder]

This isn't the place for rule clarifications, but I believe that would be considered a tether, see rule 3.i.

[Jdogg]

Hey I just had a quick question about an idea that I had. Do you think that it would be legal to attach some sort of string to my ramp, and then wind it up on the back of our vehicle? To get the target distance, all that we would have to do is adjust the length of the string. I don't believe that there's any rule against it as long as the string does not touch the floor.

^^ beat me to it.... haha

[olympiaddict]

I considered this too, but if I was an ES I would definitely consider that illegal under the "must not be tethered" and "must move as a whole" rules- although the second is more of a stretch.

[JTMess]

Hey I just had a quick question about an idea that I had. Do you think that it would be legal to attach some sort of string to my ramp, and then wind it up on the back of our vehicle? To get the target distance, all that we would have to do is adjust the length of the string. I don't believe that there's any rule against it as long as the string does not touch the floor.

This would definitely be a rules violation for several reasons. Firstly, the car must move as a whole and it could be argued that the string is moving independently of the car. Second, the car "must not be remotely controlled or tethered" and this is most certainly considered a tether. Lastly, only the wheels of the car and the ramp are allowed to contact the floor and the string would likely contact the floor as it was unwinding. I don't think this would be particularly successful anyway though, since the car would likely recoil significantly at the end of the tether.

[olympiaddict]

The only real good reason for this would be for the string to very accurately and precisely trip or release the actual braking mechanism.. but again, this is obviously illegal so no need to discuss it further.