OT: Spinning wheels

[CrazyChihuahua]

OT: Spinning wheels

Ok, I know I just made a new thread, but this doesnt suit a mat thread.

Anyhow, we have to make this balloon car for physics, which is to be powered only by a balloon. I have my idea, but I need to know hgow to get the wheels to spin. I have a box, and I want to poke holes and stick like a straw or something through it, and then put CD's on the end. But, if I glue the wheel to the straw, then the whole straw has to move, and it would be insecure in the box, and slide left and right most likely.

Now, if I glued the straw to the box, and put something thinner and longer through the straw, and glued the wheel to that, then it would say, but I dont have that thing that is thinner and longer then a straw .

Now, I have to do this for tomorrow, and yes, I know I should not have left it until now, but there would people that said they would help, but oh, they're not here... And I know how bright all of you forumers are

So anyways, any help is appreciated

 

[Shade]

How about gluing the straw in place, mounting the CDs over the ends and then gluing a cap of some sort over the end of the straw - just close enough to hold the wheels in place without too much friction.

If I can think of a better way I'll post it...

 

[Boddah_khan]

I remember doing this years ago for physics. If I remember correctly, we used CD's connected to shish-kabob skewers through a straw which was connected to the main body. The problem with cd's as wheel is that they don't have enough friction to properly grab the ground. They just spin there for the first few seconds, wasting air. Putting a layer of hot glue around the edge helped this though. Anyways, good luck!

 

[CrazyChihuahua]

The hot glue is a good idea. My brother said to put a balloon really tight around it, but that might cause some problems. And I think I have a solution:

I glue little washers that fit tightly into the centre of the CD. Then, after I put the straw through the body of the car, I glue a washer to the straw, then I put the CD on close to it, and then another washer. That way, kind of like what Shade said, it is held, and spins, but doesnt shift around too much. I just need to get it close enouugh to stay, but not cause alot of friction

 

[chase_encode]

I've seen these done before, and if I remember correctly, if you use something to make the air come out of the balloon more steady you can get your car to go further. I believe some people used paper clips (bent to precise physics angles ) to allow the air flow to be more steady. This might help with spinning wheels (acceleration).

You might take a file to the edges of the cd to get a little more traction. Just don't use your d2 cd's. :lol:

Good luck.

edit: If you live somewhere with a 7-11, you could look at the super big gulp/slurpie straws. They might be more rigid and slip over ordinary straws.

 

[CrazyChihuahua]

Well, I worked on it, and it doesnt move. I push it, it goes about a metre, and it turns out of the way. I am annoyed right now, and I am going to wait until tomorrow to do some more work on it. I figured out a way to get to do it later on in the week.

 

[sunbearie]

I've done something like that before but the one I did had to be ampibious as well. CDs are the first things that come to pples minds but they're really lousy as wheels. They're heavy annd they're really smooth (poor traction)

The washer idea is really good. Alternatively, just use big rubber bands to get things in place. You can also glue a rubber stripe on the outside of the cd to get it to move better.

 

[CrazyChihuahua]

We got a new thing now. I ditched the old idea.

I made a paper machet (sp?) pig a while ago, so we are using that. We cut off the head, and then cut it in half horizontally. Then, we hot glued it to a piece of cardboard. Then, we hot glued 3 little hot wheel cars to the bottom, and it rolls. Now we have to find a way to mount the balloon

 

[GooberGrape]

Do the rules state "powered by a balloon" or "powered by the propulsion of air leaving a balloon"??? If the rules simply state "powered by a balloon", then use the balloon as a rubber band, buy a rubber band airplane kit, and voila! I guarantee it goes miles farther than anyone else's stupid cars with CD wheels, and since it starts and ends on the ground, and is "powered by a balloon", technically you aren't breaking any rules!


GG

 

[factotum]

Do you have to actually turn the wheels using the balloon? You could always use the old-fashioned jet propulsion idea by mounting the balloon on the car and then just opening the end...