Nose Cones

Nose cones, along with fins, are one of the most critical aerodynamic components of a rocket. A simple paper cone taped on top of the rocket is enough to significantly reduce the rocket's coefficient of friction, however more complex shapes may be used to further improve a rocket's performance (and some are surprisingly easy to make). There are three common shapes used for nose cones: conical, ogive and parabolic, as shown in the diagram below.

A common misconception is that the most aerodynamis is the conical shaped nose cone. This probably comes from the fact that frequently space-going vehicles have nose cones this shape (for example the space shuttle's solid rocket boosters). However this shape is only suitable for supersonic flights (above the speed of sound). For water rockets, which only achieve a speed of about 1/4 to 1/3 the speed of sound, a parabolic shape turns out to be the most efficient. Similarly, you often see model rockets (the pyrotechnic type) with parabolic nose cones as well. Several methods exist to construct nose cones of this shape. The simplest and quickest is to use the top of another bottle cut off and taped or glued (or attached some other way) to the top of the rocket. Another technique that is used is guppying. This involves heating the bottom of a pressurised bottle so that it expands into a rounded shape. While this method does give very good results, it takes a lot of practice to get right.