Editing Water rocket (section)

===Bottle===
[[File:Two Rockets.JPG|thumb|right|Two multi-bottle rockets with a cat for scale.]]
[[File:ethereal.JPG|thumb|right|A larger multi bottle rocket with cylindrical fins.]]

Typically a single [[polyethylene terephthalate]] (PET) carbonated [[soft drink]] bottle serves as the pressure vessel. Multi-bottle rockets are created by joining two or more bottles in any of several different ways; bottles can be connected via their nozzles, by cutting them apart and sliding the sections over each other, or by connecting them opening to bottom, making a chain to increase [[volume]]. This adds complexity and the increased volume leads to increased weight - but this should be offset by an increase in the duration of the [[thrust]] of the rocket.

Multi-stage rockets are much more complicated. They involve two or more rockets stacked on top of each other, designed to launch while in the air, much like the [[Multistage rocket|multi-stage rockets]] that are used to send payloads into space.