Introduction: Balloon Power Car

I've seen several pics on various science project sites, but none have any details ....

Step 1: Materials Needed

Sorry, forgot to include pics for tools ..

Small water/soda bottle     (soda is more rigid, but harder to cut & drill)
4 bottle caps Bendable straw
BBQ skewer Party ballon
Utility knife
Drill & scissors

Step 2: Cut Opening for Ballon

Use utility knife, cut opening large enough for your finger access and ballon

Step 3: Cut Holes for Wheel & Axel

On opposite side when hole was cut, put some duct tape and mark 4 holes.
The position should be straight & close to the tape edge.

Drill from INSIDE out, then expand hole to 1/4 inches

Step 4: Drill Hole for Wheels

Cap hole diameter should be slightly smaller than the BBQ skewer. Mine was 1/32". Slip in bottle cap to bottom. It's suppose to be fairly tight fitting so wheel will not wobble.

Step 5: Mount the Wheels

The skewer axel should rotate freely, cut openings with scissors if needed. It's OK if you end with an oval shape. DON'T cut too much, else car will drag on the bottom

Step 6: Drill Hole for Ballon Mount

Tape a ballon to short end of straw tightly.  You can inflate here & check for leaks.
Thread the longer end thru, then tape it securely.

Step 7: Testing

Car should ride very nicely with no drags. Now inflate & enjoy !