Scrambler C

tanuagg13
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Re: Scrambler C

Post by tanuagg13 » July 23rd, 2014, 12:50 pm

I'll try that out this time around; I used rubber between the contact area and wingnut before that but for some reason that produced skid, so I'll go with your spring suggestion, along with a few radical design changes.
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Re: Scrambler C

Post by PHXcoach » July 23rd, 2014, 12:59 pm

I think the rubber might cause the wingnut to bind, stopping the wheel abruptly, and hence causing a skid. The spring seems to work better by adding an increasing pressure to the brake. I saw somewhere else where they were using felt, but I am not sure how that worked out.

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Re: Scrambler C

Post by A Person » July 23rd, 2014, 1:46 pm

I think PHXcoach is right. Adding a cushion shouldn't cause skid at all. I think a spring is the most widely used method, and it's relatively friction less, compared to a piece of rubber.
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Re: Scrambler C

Post by iwonder » July 24th, 2014, 6:54 pm

For my spring launcher I used surgical tubing, and augmented it with helicopter rubber to fine tune it. The other really good spring launcher I saw used pure helicopter rubber, really small stuff but probably a hundred pieces. They work really well if you fine tune them and make it consistent. The hardest part for me was getting the weight to drop onto the second trigger reliably. (Hint, I tried using string runners along the weight drop, it doesn't necessarily fix the problem). Basically as long as the weight hits the floor slowly you've moved most of the energy into the spring and you're good to go. But put a lot of effort into making your vehicle light, smooth, and use small/low inertia wheels.

As far as skidding/braking... When we added the spring launcher, the vehicle would have a tendency to skid as soon as it left the launcher, we fixed it, but watch out for that with springs, the wheels won't accelerate fast enough and the back end will slide around. For the brakes, I used a wingnut/threaded rod system, no springs/rubber washers, and we didn't have any skid at the end of the run. I've also heard of people being able to burn their tires and leave skid marks on certain floors. Since added rubber/springs can lead to small variations in the brake distance, and complicate the mechanism, I wouldn't really bother with them until you've exhausted the other options.
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Re: Scrambler C

Post by tanuagg13 » July 25th, 2014, 5:56 am

Any tips on where to get wheels?

Also, what were your run times looking like?
2015 Events (Division C):
NJ States
Mission Possible -- 1st
It's About Time -- 4th
Cell Biology -- 5th
Montgomery Invitationals (NJ)
Cell Biology -- 4th
Mission Possible -- 2nd
It's About Time -- 2nd
Regionals (UCC, NJ)
Cell Biology -- 3rd
Codes and Algorithms -- 9th

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Re: Scrambler C

Post by iwonder » July 25th, 2014, 6:09 am

We were hovering a few hundredths or maybe a tenth to .15 above one second. If y'all want specifics come on chat some time and look for me :P

(That's both a shameless plug for chat and my desire to not spill all my sources on the forums)
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Re: Scrambler C

Post by scramblingman » July 29th, 2014, 11:00 am

tanuagg13 wrote:Any tips on where to get wheels?

Also, what were your run times looking like?
servocity.com has some good ones that you can check out. All different sizes.

Also I know this is highly unlikely but does anyone think it would be possible to have an electronically powered car as the scrambler sometime in the future? It still would have an egg and have to stop at a specified distance, but wouldn't require a launching mechanism. Obviously it wouldn't be allowed to have any kind of remote control, and would have to be completely autonomous. It might be an interesting event, and would be a change of pace from what has been offered for the last few years

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Re: Scrambler C

Post by tanuagg13 » July 29th, 2014, 12:59 pm

Wouldn't that just be battery buggy?
2015 Events (Division C):
NJ States
Mission Possible -- 1st
It's About Time -- 4th
Cell Biology -- 5th
Montgomery Invitationals (NJ)
Cell Biology -- 4th
Mission Possible -- 2nd
It's About Time -- 2nd
Regionals (UCC, NJ)
Cell Biology -- 3rd
Codes and Algorithms -- 9th

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Re: Scrambler C

Post by scramblingman » July 30th, 2014, 5:47 am

Oh shoot yeah. Sorry I didn't know about that event

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Re: Scrambler C

Post by iwonder » July 30th, 2014, 7:53 am

Or electric vehicle :P

Also, I used servo city wheels for a few years, they're great and all, but if you don't treat them right the rubber ring around the outside can get quite slick and hurt braking. Other than that they're really nice, very very round and within a few thousandths of a inch of the spec'd size.
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