Scioly.org

seadog wrote:It takes our vehicle about 4 seconds to get to 9m and 6 seconds to get to 12m. Is this ok? Right now, the vehicle is made of balsa wood. Should we try to improve the vehicle by building it of lightweight metal or some other material? Any suggestions is highly appreciated. Thanks!!!!

What kind of launcher are you using? It might not be transferring enough power to your car.

Also, make sure that your wheels/axles (whichever ones spin) spin freely. If they're rubbing up against something, the ETV won't be able to go as fast. Speed is an important part of the score, especially if you can't stop at 0.0 from the mark every time without breaking the egg.

Is 1/2 inch diameter pvc too heavy

Shanta wrote:Is 1/2 inch diameter pvc too heavy

Depends on your overall system. If you can get a powerful spring launcher, it might not be too heavy. And think about your goal weight. Maybe you can use PVC in some places, but using it for the entire chassis of the ETV would be too heavy to launch. PVC is nice because it is almost unbreakable in this setting, but it is easily heavier from woods, plastics, and carbon fiber.

Also I found pictures of my device from last year. Will post them when I get the chance.

For the launcher or the car? I'm using 1/2 in PVC for the launcher.

dragon_fruit35 wrote:For the launcher or the car? I'm using 1/2 in PVC for the launcher.

Well, the weight of the material that you use on your launcher really doesn't matter all that much:P It is more so about your preference and logistics. Will it be too heavy for you to carry around? Probably not. It is nice to have a sturdy launcher so most of the energy goes into propelling the vehicle instead of shaking/moving the launcher, so a heavier launcher could help a bit, but other than that what you use for launcher material isn't of much importance, it is more so about its design. I made my mine out of wood last year, and I braced it a lot so it was sturdy. Again, it all depends on how you implement.

so would a balsa pvc hybrid for etv be good?
if so
where should i place the pvc in the back where it connects to the launcher?

So that all your angles were straight? Yes, that could work, as long as your launcher is powerful enough.

So I have been using a pulley launcher for the whole season so far, and I've been pretty pleased with the placings so far(7,6,5,4). However, my ETV (made out of balsa and CDs) was relatively slow compared to the others at the invitationals, (around 4-4.5 seconds), and inaccurate (10-20 cm). I've decided to change my launcher to a spring launcher, but I am unable to figure out how to keep the car in place when it is being launched. Does anyone know?

Eggo wrote:So I have been using a pulley launcher for the whole season so far, and I've been pretty pleased with the placings so far(7,6,5,4). However, my ETV (made out of balsa and CDs) was relatively slow compared to the others at the invitationals, (around 4-4.5 seconds), and inaccurate (10-20 cm). I've decided to change my launcher to a spring launcher, but I am unable to figure out how to keep the car in place when it is being launched.

I saw this image but I can't figure out what those metal V shaped things are. (Click to Show Hidden Text)

[img]http://i81.photobucket.com/albums/j223/nickfastswim/Science%20Olympiad/scrambler/P0008360-1.jpg[/img]

Does anyone know?

The metal V-shaped objects are used to hold the ETV in place while the spring is stretched by the falling mass. Otherwise the car would launch forward and the spring wouldn't stretch and would not provide a fast launch. So when the mass hits the other end of the V-shaped lever, it releases the car, allowing the spring to compress and pull the cart forward. I've got another approach to that I hope to post soon, just need to find the chance...

Uploaded pictures of last year's device. Some of the pictures are inconsistent (e.g. angle changing mechanism for bonus shown in fourth and fifth pictures aren't on other pictures of the vehicle as that was added later). And the mass isn't shown. Feel free to ask questions, borrow design (I certainly didn't come up with all the ideas to this myself), etc.

scioly.github.io/scioly/scrambler