Scrambler C

[ccasediaz]

So reading the rules, it doesn't seem like there would be a need to steer the vehicle based on the description of the track in the rules. When I go look at the track diagram on soinc.org, it shows a bucket at the center point, but the file says 2017 track diagram. I am assuming that the rules are the rules and that there will be an updated track diagram with no bucket? Am I missing something in the rules?

I just submitted this question on the Science Olympiad main site- the should take that track off if it is not the same as the one that needs to be used this year. The Event supervisors may get confused on how the track should be set up for the events. Reading the rules, the track needs to be straight this year only.

[jpandas2]

For those of you guys who are using spring launchers what are you using as your spring? There are so many options at the stores. Do you guys have any recommendations?

[windu34]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

If you connect the pieces of your frame with 3D printed parts, then it "should" be okay. Keep in mind, there could be 40 other things that still could be causing the steering issue, even if the frame is straight. If you 3D print structures to hold the bearings/hubs, then this can help.

Although the track is straight, your vehicle wont go straight without some mechanism of adjustment. The smallest imperfection in your steering will become evident particularly at 11m. You want something light-weight this year given the mass is only 1.5kg, which is not a lot of starting energy to work with so your device needs to be light as possible. Highly support JobB's recommendation of carbon fiber - not too expensive and its rigid which is important here. I used this braided fishing line + zip tie combo for my EV back in the day - required fine tuning the mornning before competition, but it was excellent and we were always within 2-3 cm laterally.
https://scioly.org/wiki/index.php/The_B ... ision_C.29

[windu34]

Hey, what are you guys using for pulley material? (or for the spring launcher) I'm considering using fishing wire but I don't know if it'll stretch or be too flimsy...

"Fishing line" comes in a variety of different sizes, strengths, and materials. You might find that a fishing line in braided Spectra or Dyneema would suit.

Braided fishing line will work well. I would check out this one in 60-100lb test
https://www.google.com/url?sa=i&url=htt ... AdAAAAABAD

[pumptato-cat]

Thanks! Have any of you guys had issues with fishing line untying knots? I used to have some and it was fiddly to work with... (if so, how did you fix it? this is for a spring launcher and I'm afraid of it snapping or untying at my knots)

As someone who spends time fishing, for braided fishing line, use a uni-knot
https://www.google.com/url?sa=i&url=htt ... AdAAAAABBs

Also larger diameter (lb test >60) will be better - the thin stuff will cut through materials (such as your pulleys)

[Flavorflav]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

One option is to forego the fourth wheel. It is usually more trouble than it is worth.

[pumptato-cat]

Hmm, how would you mount the egg? (sorry if this is a stupid question...) I've never thought of using a 3 wheeled car haha

[jpandas2]

Hmm, how would you mount the egg? (sorry if this is a stupid question...) I've never thought of using a 3 wheeled car haha

There should be a backstop digram on the soinc.org website where you place the egg on and then typically use a piece of tape to attach it to the backstop.

[windu34]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

One option is to forego the fourth wheel. It is usually more trouble than it is worth.

Three wheels works well in my experience to go straight. Only problem would be if your vehicle is light, you lose some stability. This is particularly important if you have a very sudden acceleration from your launcher, for example if you store the potential energy from the mass in a spring before imparting it onto your vehicle. However if you are using a heavier device and not subjecting your vehicle to high accelerations, three wheels could work well. I would also encourage you to keep your center of gravity low, that will aid stability

Note that even with three wheels, you're going to want some method to adjust steering. In my experience, it is not possible to build a perfect frame

[knightmoves]

Hmm, how would you mount the egg? (sorry if this is a stupid question...) I've never thought of using a 3 wheeled car haha

Nobody said the two wheels had to go at the back...