Now that the Maker Faire is over, you’d think I’d be sick of juice bottle boats. But I keep doodling new designs…

I had really hoped to try some radical designs during the faire, but with the volume of kids we had coming through, we had to keep things pretty simple. Nonetheless, I kept trying to get one of the older kids to build the “Auger Drive” – James was the only one willing to take the risk. In this radical departure from conventional boat-building, the whole bottle is used as a propeller. The problem is that the alignment of the fins is critical to success – too much angle of attack and it starts to act like a paddlewheel that moves the boat sideways, not enough and it spins to fast and produces little forward motion.

Here’s an idea with two fins that are used like fish tails. I could tell from making the sketch that it was going to be too complicated to build at the faire.

By cutting the bottom off of the bottle and putting a fan propeller inside, it seemed possible we could make a pretty good turbo-jet. The hard part here is getting baffles in place to keep the pressurized water from leaking back around the fan.

Mounting the propeller on the cap all those times and only just now did it occur to me that we could probably make a helicopter.