Eco-friendly alternatives to fossil fuels are venturing beyond Earth—and into space.

Al Williams and I were talking about water rockets on the podcast the other day, and I realized that this was a perfect example of an open-ended simple project. It sounds really easy: you put some ...

This allowed [Zach] to test the geometry of the parts, operation of the mechanism ... Perhaps it could even launch a two-stage water rocket?

Practise and challenge your friends! Download the Water bottle Rockets PDF(378 Kb). Adobe Acrobat is required. SAFETY: This rocket uses air pressure to fling a bottle at high speed 20–50 metres.

The launch would also be impossible for missiles whose fuel was replaced with water. While Bloomberg ... a safer and more efficient option for daily rocket operations. Solid fuel has the added ...