Bottle rockets use compressed air and water as propellants to lift an old bottle high into the air. There is a great deal of flexibility available when designing and personalizing a bottle rocket. The nose cone is a necessary feature that adds stability to the rocket's flight, but also provides an opportunity to add your own style and purpose to a bottle rocket. Nose cones can be made from paper, other plastic bottles or even plastic Easter eggs.
Paper Nose Cone
The simplest nose cone for a bottle rocket is a paper cone taped to the top of the rocket. Made from cardstock or poster board, this nose cone is not durable, but does provide adequate aerodynamics. Paper nose cones are easily colored, decorated and replaced when necessary. If using a 2-liter soda bottle, cut a circle with a 6-inch radius out of thick, sturdy paper, and then cut a straight line from the edge to the center of the circle. Curve the paper into a cone, then tape it to the top of the bottle rocket. If the rocket tumbles during flight, add a few ounces of weight to the nose cone with something like clay to improve stability.
Plastic Bottle Nose Cone
You can also cut the top off of a second bottle to use as a nose cone. Choose a bottle with a shallow curve at the top, then use scissors to cut a straight line around the bottle, opening the bottom so it can be placed on top of the rocket. Before putting the final tape or seal on this plastic bottle nose cone, roll the bottle rocket on a flat surface to make sure the nose cone is straight and correctly aligned with the rocket body. This type of nose cone can be easily weighted by removing the cap and pushing some clay into the opening before re-tightening the cap.
Easter Egg Nose Cone
Improve the aerodynamics of a plastic bottle nose cone, and add a little color, by using a plastic Easter egg as the tip of the nose cone. Cut away the neck and cap of a plastic bottle nose cone with a utility knife. Decide whether you want the rounded end or the more pointed end of the plastic egg as the nose cone tip, and glue it into place. Silicone adhesives work well on smooth plastic pieces like these to keep them secure.
Parachute Nose Cone
Nose cones can also contain small electronics like cameras. However, when fragile electronics are added, you should add a parachute to the nose cone so that the electronics survive the landing. This is a complicated task, but it can be done with small, battery-powered servos and timers placed inside a plastic nose cone. The timer turns on a servo at the highest point of the flight, which then deploys the parachute as the bottle rocket falls.