My ankle is swollen from a wasp bite yesterday so let's take a break from bugs and talk about bottle rockets.

I was playing around with various scrap bottles over the weekend and came up with this little hack. Basically cut the bottom from a 1-liter bottle, glue some sturdy fins on it, and now you have a modular rocket shell which most small soda bottles slide right into. There's a little slop to the fit, which could be shimmed, but I found that it doesn't matter with most shots, especially if you center it before takeoff.

This design flies straight up and then sort of flutters back to the ground, sometimes the two bottles separating. I think the heavier duty plastic screw top is just enough weight to stabilize things without causing the dreaded "plummet of doom."

Update: put little tabs of one-side sticky window insulating foam on the inside, aligned with each fin and the inner bottle stays centered and snug.

info