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Experiment with rocket designs and a PVC launcher to discover how high—and how far—you can make your rockets go.
For the launcher:
For the rocket:
Note: The exact lengths of the PVC are not critical. Ask your hardware store to saw your PVC pipe into the lengths you need. If they cannot accommodate this request, you’ll also need a hacksaw blade or PVC cutters. If you’re using a hacksaw blade, wrap one end with duct tape to make a "handle" so you can safely cut the pipe.
Build the launcher
Build the rocket
Ready for liftoff?
Now that you’ve got both a rocket and a rocket launcher, you’re ready to go. Find an appropriate launch site without overhead obstacles (wires, ceilings, trees, etc.). Make sure no one will be in the path of the rocket, and then you can start your countdown.
Slide your rocket onto your rocket launcher, and send that rocket flying with a good stomp on the 2-liter bottle. (Caution: Be sure to use only one foot when you stomp on the bottle. Using both feet to stomp can cause the stomper to slip and fall.)
When you’ve got your technique down, experiment to see how changes to your rocket will affect its flight. Roll your sheet of paper the long way instead of the short way (or vice-versa) and see what happens. Try out a new fin shape or a different angle for the V of the rocket’s nose. Can you think of other designs to experiment with? Build new rockets, predict how they’ll fly, and see what happens.
In order to move through the air, a rocket has to push air aside. Things that are designed to travel quickly, such as sports cars and jets, are shaped to minimize the amount of air they push aside to move forward. Your paper rocket has been designed to move through the air efficiently, too. The V-shaped nose helps it cut through the air as it flies; the fins help keep the rocket moving in a straight line.
If you tried two different-length paper cylinders for your rocket experiments, you may have noticed that the longer rocket flew further/higher than the shorter one. This is because a long rocket body has more distance (length of rocket) over which the force of the air from the PVC tube is applied, which increases the amount of time during which the force is applied. As the air expands into the pipe and rocket, however, the force decreases, so there is some optimal length of rocket where force and time are maximized.
The launching force is created by stomping on the 2-liter bottle. Increasing that force will make the rocket go higher/further. The change in velocity is proportional to how much force you apply and the time during which the force is applied. The change in velocity is inversely proportional to the mass of the rocket. Therefore, lighter rockets tend to go further/higher.
These variables—the force of the stomp, the length of time during which the force is applied to the rocket (which, in this case, translates to the length of the rocket), and the mass of the rocket—all affect how high and far the rocket flies.
With an additional PVC elbow, another 1-foot (30-cm) length of PVC pipe, and one PVC T-joint, you can rearrange the pieces of your launcher to launch two rockets simultaneously. (Hint: Start by replacing the two end caps of your original design with the two elbows.) How would a “double rocket” launch affect each rocket’s flight?
If you want, you can also measure the height of a rocket’s flight using the inclinometer in the Height Sight Snack. To use the method described there, the launch angle of the rocket would need to be 90 degrees, so be sure to launch the rocket vertically and keep both eyes open as you track its flight.
If you have several people measuring the rocket's flight, you can average their inclinometer measurements to most accurately determine the rocket's height. If only one person is measuring, try launching the same rocket several times, and record and average those sets of measurements.
This Science Snack is part of a collection that showcases LGBT artists, scientists, inventors and thinkers whose work aids or expands our understanding of the phenomena explored in each Snack.
Anne McClain (pictured above) is a lieutenant colonel in the U.S. Army, an engineer, and a NASA astronaut. She was a flight engineer for Expedition 58/59 to the International Space Station. Lieutenant Colonel McClain, a Senior Army Aviator, has more than 2,000 flight hours in 20 different aircraft. With the Bottle Blast Off Science Snack, you can simulate some of her flights by building your own air-powered rocket and launcher and measuring how high you can go.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Attribution: Exploratorium Teacher Institute