Model rocket kits often use a similar length of straw attached to the rocket body. This straw is threaded through a metal rod on the launching pad to keep the rocket upright before launch.
You can try to make the balloon rocket with a round balloon instead of a long one, as well as various straw lengths to see how well they guide the balloon rocket. You can also raise the angle at which the balloon rocket flies to see how it affects the distance the rocket travels. A related device you can make is a jet boat: Cut a milk carton in half lengthwise. Make a hole in the bottom end and thread the end of a balloon through it. Inflate the balloon, then put the boat into a partially filled tub of water and release the air.
Be sure to use a pencil or dowel slightly thicker than a drinking straw, but not much thicker.
Always point the straw and rocket upward, not toward anybody when launching. Vary how you build the rocket to see how the modifications affect its flight. Also, vary how sharply you exhale into the straw to see how it affects the distance your rocket flies. A toy similar to the paper rocket consisted of a stick with a plastic cone attached to one end and a plastic parachute attached to the other. The parachute was folded over the stick, which was then inserted into a cardboard blow-tube. When blown into, the plastic cone would catch the air and launch the stick. When it reached maximum height, the stick would fall, deploying the parachute.
A good diameter is 1. 5 inches (3. 75 cm)[3] X Research source , but the actual diameter will be determined by the diameter of the rocket’s combustion chamber.
Look for a film canister whose lid has a stopper-like projection that goes inside the mouth of the canister instead of being held in place by a lip on the outside of the canister mouth. If you can’t find a film canister, you can use an empty prescription medicine bottle with a snap-on lid. If you can’t find a bottle with a snap-on lid, you can whittle a cork stopper that will fit tightly into the bottle mouth.
Be sure to have the mouth of the canister or pill bottle pointing out when you attach the rocket frame to it. [5] X Research source The mouth will serve as the rocket nozzle. Instead of folding the end of the rocket body away from the canister into a nose cone, you can make a separate nose cone by cutting a paper circle, cutting from the edge just to the center, and folding the cut circle into a cone. You can affix the cone with either tape or glue. Add fins. Because this rocket is thicker in diameter than the paper rocket you launch with a drinking straw, you may want to cut individual fins to attach. You may also want to have three fins instead of four.
Instead of using water, you can instead fill the canister about half full of vinegar. In place of the effervescent tablet, you can use 1 teaspoon (0. 18 ounce or 5 g) of baking soda. Vinegar, an acid (acetic acid), reacts with baking soda, a base, to produce water and carbon dioxide. Vinegar and baking soda are more volatile than water and effervescent tablets, however, so you need to get out of the rocket’s way a lot faster – and using too much of either chemical may rupture the canister. [6] X Research source
Bend the outer bend to a 60-degree angle. This will form the base of the launching pad. Bend the inner bend upward, then around to form an open-ended triangle. This is where you will rest the foil-wrapped match head.
Be sure the surrounding area is clear before launching the rocket.
Have a pail of water handy to dunk spent matchstick rockets in to ensure they are completely extinguished. If a matchstick rocket should land on you, stop moving, drop to the ground, and roll until any flames are extinguished.
Remove the bottle label by cutting where it isn’t glued to the bottle. Be careful not to scrape or poke the bottle surface when doing this, as a scratch or cut will weaken it. Reinforce the bottle by wrapping it with strapping tape. New bottles can withstand pressures of up to 100 pounds per square inch (689. 48 kilopascals), but repeated launching will reduce the amount of pressure the bottle can handle without rupturing. [8] X Research source You can wrap several bands of tape around the center of the bottle or wrap the bottle around its center and halfway from there to either end. Each band should go around the bottle twice. Mark out the places where you want to attach fins to the body with a marking pen. If you plan to have four fins, draw lines 90 degrees apart. If you plan to have three fins, draw lines 120 degrees apart. You may want to wrap a strip of paper around the bottle and make your markings on it first, then transfer the markings to the bottle.
First, you’ll need to design your fins and create a paper template to serve as a cutting guide. However you design your fins, they should be designed so that the actual fin will be folded over (doubled) for extra strength and will reach to at least the point where the bottle narrows. Cut out the template and use it as a guide to cut into the fin material. Fold the fins into shape and attach them to the rocket body with strapping tape. Depending on the design of your launcher, you may not want to have the fins extend below the mouth of the bottle/the rocket nozzle.
Cut the bottom out of the bottle. Place a payload in the upper section of the cut bottle. This can be a piece of modeling clay or a wad of rubber bands. Place the bottom section of the cut bottle inside the upper section, with the bottom toward the mouth of the upper section. Tape it in place, then tape the modified bottle onto the bottom of the bottle serving as the pressure chamber. Your nose cone can be anything from a 2-liter bottle cap to a length of PVC pipe to a plastic cone. Once you decide on the nose cone and assemble it, it should be permanently attached to the upper section of the cut bottle.
After you’ve found the center of mass, weigh the rocket. It should weigh from 7 to 8. 5 ounces (200 to 240 g).
Find a cork that fits snugly in the mouth of the bottle. You may have to shave the edge slightly. Get a valve system of the kind used in an automobile tire or bicycle inner tube. Measure its diameter. Drill a hole in the center of the cork with a bit of the same diameter as the valve. Clean the valve stem and put a piece of tape over its threaded portion and opening. Thread the valve through the hole in the cork, then seal it in place with a silicone or urethane sealant. Let the sealant dry completely before removing the tape. Test the valve to make sure air passes freely through it. Test the stopper by putting a small amount of water in the rocket pressure chamber, then put the stopper in place and stand the rocket upright. If you find any leaks, reseal the valve and test again. Once you have determined there are no leaks, test again to find the pressure at which air forces the stopper out of the bottle. For instructions to build a more sophisticated launching system, see http://www. sciencetoymaker. org/waterRocket/buildWaterRocketLauncher. htm.
An elevated surface such as a picnic table is a good idea when small children are present. [10] X Research source
Fill the pressure chamber 1/3 to 1/2-full of water. [11] X Research source (You may want to add some food coloring to the water to produce a more colorful “exhaust” when the rocket launches. ) It is also possible to launch the rocket without putting any water into the pressure chamber, although the target pressure may be different than that when the chamber has water in it. Insert the launcher/stopper into the mouth of the pressure chamber. Connect the hose of a bicycle pump to the launcher valve. Stand the rocket upright. Pump air until you reach the pressure at which the plug should be forced out. There may be a slight delay before the plug is forced out and the rocket launches.
