Gravity Vehicle C

[fishman100]

So Stingray355 what is your average score

Don't know about his average score but the winning score at the Tiger Invite was about 250, if I recall.

Are teams adjusting the length of the car to match a certain launch height for a given distance or does everyone have just 1 care for every height? We're currently trying to figure out if this might be a viable option, but we haven't worked out all the math yet.

Also, this might not be relevant until future competitions (when the competition really starts coming down to a a few points), but is there a way to ensure you're launching at a specific height? (ie you place the car where you measured the height as 50cm, but the ES measures the height as, say, 51 cm.)

[Stingray355]

We don't track that except to compare scores for a particular distance/height combination. It runs very consistently and so far has been pretty competitive, two 1sts and a 2nd in three outings. (the 2nd was with a broken/bent front axle so we were lucky to finish that well) Anyway the scores in competition have ranged from below 200 to less than 300 with the distance contributing the biggest difference in outcome. Our boys have worked very hard to calibrate the vehicle for all possible combinations. It has helped them learn what combinations/settings work best for each possible distance and it has also made them very proficient at adjusting the device. We don't have access to data from our competition so we focus on simply trying to get the best from our own device. I bet that would serve you well too. Good luck.

[jacobxc]

We don't track that except to compare scores for a particular distance/height combination. It runs very consistently and so far has been pretty competitive, two 1sts and a 2nd in three outings. (the 2nd was with a broken/bent front axle so we were lucky to finish that well) Anyway the scores in competition have ranged from below 200 to less than 300 with the distance contributing the biggest difference in outcome. Our boys have worked very hard to calibrate the vehicle for all possible combinations. It has helped them learn what combinations/settings work best for each possible distance and it has also made them very proficient at adjusting the device. We don't have access to data from our competition so we focus on simply trying to get the best from our own device. I bet that would serve you well too. Good luck.

So is your car consistently straight, because I know our car is very temperamental and changes all the time. But we somehow always get it aligned each week.

[Stingray355]

The short answer is yes, very straight every time. The video on YouTube is much darker than than the original file but I think you may be able to see this. They practice in a hallway and the center of the ramp is lined up with a seam in the tile. The paper clip is on the left side of the device right behind the left front wheel. As the vehicle travels the distance you can see it drift to the right, this is calibrated in so that the pointer stops over the target, if all goes correctly anyway. We could have simply lined up the vehicle pointer to the target as it sits on the ramp but during early testing we lined up on the center of the ramp and never changed. Steering is adjustable so it is just a matter of knowing how much to dial in for each distance. The floor at each competition is always a variable so some adjustments are always needed to compenate for that. Glad to hear you are able to get yours to run straight when it counts but you might want to look into why it doesn't every time. Is the floor you test on level? Drop some marbles or ball bearings and see what happens. Be sure to pick them up so someone doesn't get hurt of course.

[joeyjoejoe]

I'm curious what kind of floors you have run on. We built a small amount of skid (30-50mm avg) into our design to get an optimal TS+HS. We had it down to a science but the first time we ran our car on the lanolium floors in the school hallway instead of the wooden floors in the gym, our skid roughly halved which obviously increased our DS.

Also, at the invitationals that many of you have participated in, were you able to adjust your ramp between runs? Could you aim your ramp or change the height you launched your car from for the second run?

Lastly, I don't think the students are allowed to walk out on the track after launch. Will they be informed of their distance score AND whether it was long or short so they can make adjustments?

PS: Stingray: Scores below 200!!! Wow! That's what we're getting just for TS+HS for 9m+. Our distance scores are typically in the 50-70 mm range mosty due to a poorly aimed ramp. If anybody's got an points about a better way to aim the ramp (we aren't assuming the center point and the target are perpendicular), I'd love to hear it.

[Stingray355]

Calibrating a skid for different floor surfaces is a challenge, good luck. If the rules don't prohibit something, this includes the general rules of conduct, then you would expect it to be allowed. The event supervisor will determine the specifics in my experience . We moved our ramp last year as the primary adjustment and never had any issues as long as you stay within the designated area. I don't think that changed this year but we changed our design and no longer move the ramp between runs.
Rule 5L allows you to retrieve your vehicle once the official tells you it is OK to do so. I think most experienced supervisors try to avoid handling the devices and want to avoid the possibility of picking it up and damaging it so they want you to retrieve your own stuff. Also the official measurement is point to point and I think most devices are adjusted for distance and direction separately so you need that info to make any necessary adjustments.

The lower than 200 score was not for 9 meters. If you are consistently getting to within 50-70mm of the target that is pretty good . If the method of adjustment is repeatable you should be able to dial that in even closer. However if you are trying to do it by moving the ramp without any kind of reference I think that would be tough to make consistent. For example say your first run was 50mm to the left of the target and all of the error was in that plane. If your adjustment was to move the ramp over 50mm you would have to be able to isolate that as the only change. If you inadvertantly changed the angle of the ramp by even 1 or 2 degrees that will have a substantial impact on where the vehicle will travel especially out 8 or 10 meters.

If you run your vehicle on the exact same settings 5 times and use a small piece of tape or something to mark each result on the floor, how close would the five markers be? This will measure the consistentcy of your ramp/vehicle/setup procedure. If the result is a tight group then you know how consistent your device can be and then you can focus on a more reliable precise way to adjust between runs. Many teams including ours use some kind of sighting device. It does not have to be complicated and electonics are not allowed.

One final thought since we never know what kind of floor we will run on we have built a device that is not sensitive to the differences. In your situation it might be worthwhile to test on different floor surfaces and simply add a correction factor to your primary calibrations. For example if you found that at 8 meters there was a Xmm difference between vinyl and wood floors simply factor that in when you are faced with running on wood floors. You would still have to make several runs on each type of floor at each of the various distances to collect enough data but it would be quicker than recalibrating. Combine this with the result of your first run, in competition, and you should be able to make a decent adjustment for your final run. Better than a WAG anyway.

[JustDroobles]

I will soon be running this event at a regional tournament and I want to be sure of this. Does the 8 minute time stop when the team alerts the supervisor they are ready to do their run? Then the supervisor measures the vehicle height, the team runs the vehicle, and the supervisor measures the distance score. Then the 8 minute countdown resumes and the team is allowed to retrieve their vehicle.

[ArchAngel]

I really need some help figuring out my release mechanism. I have no ideas whatsoever. Can anyone give me SOMETHING?

[jacobxc]

I really need some help figuring out my release mechanism. I have no ideas whatsoever. Can anyone give me SOMETHING?

It would help to see what we are dealing with

[ArchAngel]

What do the rules mean by a non horizontal position?

My ramp towards the top is horizontal, but when the vehicle i laid flat out on the ramp, in the launch position it isn't completely horizontal, is that acceptable.

Also just to be clear to trigger the release of the vehicle, you must touch the release mechanism with the pencil?
Can you touch ANY part of your car/ramp/mechanism with the pencil?
In the rules it says you may not touch ANY PART but it does nto specify if you can with the pencil or not.