## Gravity Vehicle C

windu34
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### Re: Gravity Vehicle C

My current design, not built yet, has a spring on the end of the axle. The wingnut will start to slow down from the spring, but will not immediately stop the vehicle. I'm sure this is a common idea, though. Has anyone tried this?
I've been trying to find out how this works as well, but I was wondering how the car would fully come to a stop since it is never going to hit up against something to make it come to a full stop?
The wingnut will compress the spring. The spring will eventually either be all the way compressed, or it will exert a significant enough force against the wingnut, both of which will stop the vehicle. Writing this now makes me realize that, if you're not careful, the spring may be able to push your vehicle backward.
I would stay away from compressing springs and use the springs in tension instead to avoid variability and increase reproducibility with springs
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### Re: Gravity Vehicle C

I've been trying to find out how this works as well, but I was wondering how the car would fully come to a stop since it is never going to hit up against something to make it come to a full stop?
The wingnut will compress the spring. The spring will eventually either be all the way compressed, or it will exert a significant enough force against the wingnut, both of which will stop the vehicle. Writing this now makes me realize that, if you're not careful, the spring may be able to push your vehicle backward.
I would stay away from compressing springs and use the springs in tension instead to avoid variability and increase reproducible with springs

That's what I mean though it will not come to a complete stop basically like ever, since it can by pushed back unless you have the exactly perfect spring which can be hard to find, so I wondering if there was a better way to use the spring but have a break that consistently stops the same way.

And I was wondering what you mean by using them in "tension" or so to say, since how does it get pulled rather then being pushed. Thusly, due to my confusion, I was wondering if anyone who did this before could give us some insight.

Moreover, what type of spring would you try to use then, since there could be many options open if you went for tension springs.
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PM2017
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### Re: Gravity Vehicle C

My current design, not built yet, has a spring on the end of the axle. The wingnut will start to slow down from the spring, but will not immediately stop the vehicle. I'm sure this is a common idea, though. Has anyone tried this?
I've been trying to find out how this works as well, but I was wondering how the car would fully come to a stop since it is never going to hit up against something to make it come to a full stop?
The wingnut will compress the spring. The spring will eventually either be all the way compressed, or it will exert a significant enough force against the wingnut, both of which will stop the vehicle. Writing this now makes me realize that, if you're not careful, the spring may be able to push your vehicle backward.
You'd need a pretty ridiculously strong spring for backdriving to be an issue.
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### Re: Gravity Vehicle C

I've been trying to find out how this works as well, but I was wondering how the car would fully come to a stop since it is never going to hit up against something to make it come to a full stop?
The wingnut will compress the spring. The spring will eventually either be all the way compressed, or it will exert a significant enough force against the wingnut, both of which will stop the vehicle. Writing this now makes me realize that, if you're not careful, the spring may be able to push your vehicle backward.
You'd need a pretty ridiculously strong spring for backdriving to be an issue.
Try rotating a worm gear by spinning the spur gear it meshes with - it doesn't work. Similar concept here.
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sciolyperson1
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### Re: Gravity Vehicle C

For all of the people using springs as a backstop helper/slower, how would that work? The springs found in normal ballpoint pens for example are way too thin, any spring really unless it's huge wouldn't make any difference. Since the wingnut has so much torque coming from the ramp and the rotation of the wheels and axle (especially if you have high TPI), any normal spring's effect would be minimal, and there would be no performance difference between a springed backstop and a non springed backstop.

Remember, a lot of cars are going to be 2kg - which means that one tiny spring will not make any difference whatsoever.

Adding on to what windu34 briefly touched upon, springs introduce a new variable into results and between runs, final distances may not be the same.
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### Re: Gravity Vehicle C

^ What sciolyperson1 said
And compression springs especially are very finnicky, and I learned this the hard way last year. However, tension springs don't have the disadvantage of inconsistency so it may still be worth looking into.

Has anybody experimented with braking/slowing methods other than the wingnut system?
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sciolyperson1
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### Re: Gravity Vehicle C

^ What sciolyperson1 said
And compression springs especially are very finnicky, and I learned this the hard way last year. However, tension springs don't have the disadvantage of inconsistency so it may still be worth looking into.

Has anybody experimented with braking/slowing methods other than the wingnut system?
Missed my point, neither tension springs nor compression springs will make any significant affect on the wingnut. Moreover, tension springs affect the wingnut more for when its stretched more (12m) and less for 9m. Which means that at 9 meters it wont, and cant, make any difference - if it makes a difference in the speed at 9m then it wont reach 12m.
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### Re: Gravity Vehicle C

^ What sciolyperson1 said
And compression springs especially are very finnicky, and I learned this the hard way last year. However, tension springs don't have the disadvantage of inconsistency so it may still be worth looking into.

Has anybody experimented with braking/slowing methods other than the wingnut system?
Missed my point, neither tension springs nor compression springs will make any significant affect on the wingnut. Moreover, tension springs affect the wingnut more for when its stretched more (12m) and less for 9m. Which means that at 9 meters it wont, and cant, make any difference - if it makes a difference in the speed at 9m then it wont reach 12m.
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windu34
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### Re: Gravity Vehicle C

^ What sciolyperson1 said
And compression springs especially are very finnicky, and I learned this the hard way last year. However, tension springs don't have the disadvantage of inconsistency so it may still be worth looking into.

Has anybody experimented with braking/slowing methods other than the wingnut system?
Missed my point, neither tension springs nor compression springs will make any significant affect on the wingnut. Moreover, tension springs affect the wingnut more for when its stretched more (12m) and less for 9m. Which means that at 9 meters it wont, and cant, make any difference - if it makes a difference in the speed at 9m then it wont reach 12m.
Not necessarily. Youre assuming the spring is in tension for the entire time. I would suggest using very high K coeff springs and having them "engage" only when the vehicle is ~1.5-2 meters away from the target. Essentially you would have slack in the system during most of the run.
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### Re: Gravity Vehicle C

Hey I was reading the rules, and had a question. It says that the vehicle and ramp in the ready to run stance have to fit in a 50 by 50 box, so is it ok if the vehicle is longer than that as long as it fits in the box on the ramp?
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