Balloon powered mini-racers, need design ideas!

[Julie GT07CS]

Have you ever made a balloon powered racer? Our son needs to make one for science class.

Here is the basic list of supplies he has to use:
large Jell-O box (empty;-))
two small straws
large straw
rubber band
balloon

In addition:
He can incorporate an extension that either lengthens the body of the car or supports the balloon.

No pre-fabricated wheels are allowed. He has to create his own out of bottle caps, spools, etc...

Cars must have at least 3 wheels. If two sets of wheels are used, one set must spin independent of the axle and the other set must be attached to the axle.

To get an A, his car must move at least three meters (approx 9-1/2 ft for good measure), have extensions, one set of wheels turns together with the axle and the other set of wheels turns on the axle freely.

There are lots of variables that come into play with the outcome, how big of a balloon, size of wheels, how long you can make the car, etc...it sounds simple but I think it will take a lot of trial and error, which will be fun. Yeah, I could Google info but it's much more fun seeing what SVTP engineer/design peeps can come up with. :beer:

Oh, before someone makes a comment why he shouldn't need my help, he is (high functioning) autistic so he needs a little help from us. He wants to build a kick-ass car! :rockon:

 

[HYBRED]

I'm guessing the car has to be powered by a deflating baloon? We did something similar in one of my intro classes, but we had to use a mousetrap so I don't think any of our tricks would work. I'll see if I can think of something.

 

[thomas91169]

use compact discs for the wheels. they are aerodynamic (like zero cross-sectional area) and have so little rolling resistance.

the axle needs to have a good set of wheel bearings that connect it to the chassis. however this may add weight to the vehicle, but it may also add rolling mass that may help it travel further.

 

[HYBRED]

use compact discs for the wheels. they are aerodynamic (like zero cross-sectional area) and have so little rolling resistance.

LOL, we did this on our mousetrap car, but we had to wrap rubber bands around them for traction.

 

[ttk53]

us the small straws as an axle housings and the large straw for the nozzle for propulsion.

I remember this from when I was in like 3rd or 4th grade, took it outside at lunch and made a boat out of it.

oh to be young.

 

[Scottyk]

Traction is what screws most people in this.. Us something like hybred said and use rubberbands or something to get traction. "most of them just spun out of control" pay alot of attention to wheels and tires to make sure they're secure, stable and pointed straight. The longer wheelbase the better, CD'S would work great but you need some type of jig or something to make sure you get them straight and stable with whatever your using for a bearing/bushing on the axle. good luck with it

 

[Julie GT07CS]

LOL, we did this on our mousetrap car, but we had to wrap rubber bands around them for traction.

That's brilliant!:rockon:

I was saving some liter bottle caps because they have ridges around them but I bet they still slide.

 

[thomas91169]

yes but the balloon will be providing the thrust in this case, i dont see the need for traction.........

that is, if im understanding the rules correctly. sounds like you guys build a chassis and mount a baloon on it, and see how far it goes right?

 

[openaccount]

Single most important part are the wheels.

What kind of surface is this run on? School floors? the titles?

Use CD's for the wheels(or something with a LARGE diameter but super slim width). It can be tough to get them to go on straight but it is by far the best set up. We used them on our Mouse trap car and it CRUSHED everyone.

After using CD wheels make sure they spin as smoothly as possible. The Balloon will provide little to no power so coasting is where the distance comes from.

I think we Used Tape(strong tape) on the CD and filled it with Epoxy making a hole DIRECTLY through the middle until it held. It isnt SUPER durable but if you do it right it will support the box+balloon.

 

[Julie GT07CS]

yes but the balloon will be providing the thrust in this case, i dont see the need for traction.........

that is, if im understanding the rules correctly. sounds like you guys build a chassis and mount a baloon on it, and see how far it goes right?

Correct. I think the traction may help it go in a straighter line? :shrug: Kat will know. ;-)

 

[SNAKE CHARM]

I used this link to help me and my daughter get some ideas for her car. Hope it helps and good luck!

NASA Balloon Car Contest

 

[Julie GT07CS]

I used this link to help me and my daughter get some ideas for her car. Hope it helps and good luck!

NASA Balloon Car Contest

Oooooh, thanks! :-D

He just got home an informed me he has to bring the stuff to build it TOMORROW! Good grief. :rollseyes

 

[thomas91169]

lol that means its been an assignment for about a week or so..........

have fun! We did the same in grade school but the rules were that it just had to be powered via thrust and it was based on distance. We used a 2l bottle for the chassis, stuck some Knex rods through, used more knex as bearings (the white ones with 8 attachment points work well when glued to the CD). we won by 2x the distance of the closest person, who also built theirs out of a 2l bottle and knex but used the wheels that come with the Knex toysets. the CD's were the key to distance.

 

[Julie GT07CS]

Actually, he just started school this past Monday. :whine: This teacher is brutal lol.

So we just went to the NASA link and there were some really cool cars! We liked this one except he is not allowed to make this type. :bored:

 

[BigSweezey]

Helped my cousin with one of these a while back.
We used the plastic gatorade bottle caps for the wheels.
We ended up more or less flattening the box we were using for the body.
The biggest problem we had was securing the balloon....having something tight enough to hold the balloon in place, but letting it be filled with air at the same time.

 

[s_x_i]

Can you cut the balloon into thin strips and make a rubber band motor out of it, or is that against the rules? :lol: