Rocket Building Made Easy.

These building techniques are the result of the genuis and hard work of the "Internet Water Rocketeers".  See the LINK section at the end of the instructions so you can start visiting these rocket scientists on-line.

It is best to begin making rockets using 2-liter Pop Bottles. When selecting a bottle to use consider the following:

• If it didn't hold fizzy pop, don't use it! Bottled water bottles may not be as strong as those containing carbonated beverages..
• 20oz & 1-liter bottles are shorter than 2-liter bottles. Make sure they fit all the way down the launch rod on your launcher. You may need a shorter launch rod to launch these bottles.
• Some bottles have narrower mouths than others (rare but true). Make sure it fits over ½" PVC pipe.
• They are made out of a plastic called PET.
• They are made to hold about 70psi but can hold 100-120psi with care.
• The circumference of the bottles vary by manufacturing batch and brand. (In general, Faygo bottles seems to have a smaller circumference than Coca-Cola bottles.) Most bottles will measure between 13 and 15/32 inches to 13 and 21/32 inches. (Thanks to http://www.h2orocket.com/ for this amazing fact!)
• The actual bottle thickness varies depending on manufacturing process.
• You lose your deposit when you cut and glue them up.

We are going to make a rocket using some simple techniques which creates reusable parts, and increases safety. The rocket will have a fin and nose cone section that will slide over the main bottle. This allows you to reuse or replace these sections easily in case of damage.  It also allows the main bottle to withstand the pressures used.  The outer sleeves will help contain any rupture of the inner bottle due to excessive pressure.

To make this rocket you will need several 2-liter bottles, some materials for fins (1/8" or less plastic or stiff balsa wood), a tennis ball or swimming noodle for a nose cone, some DUCT TAPE, Household GOOP adhesive, a razor knife, heavy scissors, and a small saw.

The rocket will have a single bottle as its pressure vessel. Fins will be attached to a wide band cut from a second bottle which will slip over the nozzle end of the pressure vessel. The nozzle end of this second bottle will slip over the flat end (bottle bottom) of the pressure vessel forming the top of the rocket. A nose cone made from a tennis ball or swimming noodle will be the final touch.

First collect a bunch of 2-liter pop bottles. I would suggest getting a few Faygo bottles and a few Coke bottles. Using a permanent marker, mark each bottle as to the brand. Next you need to remove the labels. We need to find 2 bottles that will slide over one of the other bottles. If possible measure the bottle circumferences to the closest 1/32 inch. If that isn't possible, you will have to cut the bottom off a bottle and see if it will slide over another one. You will keep the smaller bottle in one piece and cut the larger one into several parts.

To help make the cutting safer and easier for kids, do the following.

First mark the larger bottle where you want to cut it.  The easiest way is to rotate the bottle while holding a marker pen against the bottle.  Do this for each place you need to cut the bottle.  For this project you need to make two lines.

• Make the first line near the bottom of the bottle.  If you look at the side of the bottle near the bottom, you will see a mold line in the plastic where the bottom joins the side of the bottle.  Make your first line here.
• Make the second line about 1/2 way up the bottle.

Next have an adult use a razor knife to make a cut on each line about 1-2" long.  This will allow the kids to use the heavy scissors to cut along the line.  For our purposes the kids just need to make a fair cut along the line.  If they stray a little bit, don't worry it won't really mess anything up.

Now you just need to follow the illustrations below to create your rocket.

The nose cone is the nozzle end of a 2-liter bottle that can slip over our rocket body. There should be about 4-5" of bottle down from the rounded shoulder. The top of the nose cone can be either a tennis ball that is slit to cover the bottle cap on top, or it can be shaped from a swimming noodle. If using a swimming noodle, just drill or cut out a 1" hole on the bottom of the noodle so the bottle cap can fit inside. A SUREFORM tool is best way to shape noodle material.
 
 
 

This is the main body of our rocket. It is a plain 2-liter pop bottle with the label removed. Use a hairdryer to remove the label. Turpentine or "GOOF OFF" works well to remove glue residue. Remember to store the rags you use safely to prevent fires.
 
 
 
 

Here is the fin section. You can have 3 or 4 fins glued to a 4-5" band cut from a larger bottle. Glue them on with Household GOOP glue. Masking tape can be used to hold fins in place while drying.
 
 
 
 
 
 
 
 
 

Here is the rocket fully put together.
 

The noodle nose cone (or tennis ball) has been fitted over the bottle cap of the top section. The top section has then been slid over the top of our rocket body. Use Duct Tape or other Adhesive tape to fasten this section to the main rocket body. Don't slide the rocket body way up inside the nose cone section. Leave as much empty space as possible. This makes a crush zone for those hard landings.
 
 
 
 
 

The fin section slides up over the bottom and is also taped onto the main rocket body. Tape the fins on the body as low as possible without interfering with your launch mechanism.
 
 
 
 
 
 
 
 
 

As a final step, use a razor knife to chamfer the opening of the rocket nozzle. Angling the inside nozzle opening will allow it to more slide onto the launcher  a lot easier.
 
 

SAFETY TIPS

• Most 2-liter pop bottles can take up to 100-120 PSI of pressure without much problem. The National Science Olympiad uses 75psi for their launches. I use 100psi when I can. Bottles that have been abused, or weakened by inappropriate adhesives and landings can burst under pressure. It is important to keep people away from the bottles while they are being launched.
• Bottles leave the launcher at tremendous speeds 30+mph (more like 60-80mph). It doesn't feel good to get hit by one. So never lean over a bottle on the launch rod. Make sure launch rod is always pointing up when applying air pressure to a rocket.
• DON'T USE DRY ICE to pressure the water bottle rocket!!! Dry Ice can pressurize your rocket so fast that the rocket may explode rather than launch. Don't lose fingers for doing something stupid.
• Bottles that go up, must come down somewhere. Please launch rockets in open areas so they don't land in streets or on your neighbors car or roof.
• Liquid Nails, Super Glues, and HOT Glue Guns have been known to weaken the plastic used in pop bottles. Low Temp Glue Guns can be used. PL Premium (a construction adhesive found at Home Depot next to Liquid Nails) and HOUSEHOLD GOOP work good for making rockets. PL Premium is best for gluing bottles together to make bigger rockets. Household GOOP is best for gluing fins onto bottles.

LINKS to other Water Rocket Sites

This is just a partial list of the many fine sites on the Internet dealing with Water Rocketry.  Check back soon for a more complete listing.

• http://www.h2orocket.com/ to see lots of rocketry information. (the address is h2oh NOT h2zero).  Thissite features the Bigfoot Launcher that is the standard of the industry.  If you are going to be running lots of water rocket events, consider a Big Foot Launcher for reliability and safety.   It is the best product available.
• Bruce Berggren is the first person to reach the 1000' altitude mark.  Using a two stage water rocket at 100psi, the rocket reached the 1000' barrier.  Lots of good information here on launchers.  His site is: http://www.geocities.com/CapeCanaveral/Lab/5402/
• Rocketry down under in Australia.  http://www.osa.com.au/~cjh/rockets/