100-Yard Paper Rocket Launcher

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About: I'm a writer, maker, and educator who's on a mission to better the world through hands-on engineering projects. Check out my work: www.MadeForSTEAM.com

This is my take on the compressed air paper rocket launcher. Enjoy!

Be sure to check out Made for STEAM, an amazing collection of hands-on projects for kids!

https://www.madeforsteam.com/

Step 1: Materials List

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Tools for the air pressure chamber:

Materials for the air pressure chamber:

Electric Trigger mechanism


For the base:

  • 12" cable ties
  • PVC elbow joints (x2)
  • 12" piece of PVC with two holes drilled about 4" apart (x2)
  • 8" piece of PVC


The total cost is about $70, excluding all tools and solvent weld. In my line of work, it is well worth the initial investment because the paper rocket activity is very cheap, less than $0.15 per student.

For paper rockets:

Step 2: Make the Launcher

This launcher works up to 60psi. You can wire in a second 9V battery to get the launcher up to 100+psi. 60psi is enough to achieve spectacular results. Pressures above 60psi dramatically increase the risk of exploding the rocket.

(and by the way, you might want to protect your work surface a bit better than I did)

The button circuit was originally purchased from a website that no longer exists. However, it's very simple to build yourself. Simply wire the button, 1 or 2 9V batteries, and the wires from the electronic sprinkler valve together in a single series.

Step 3: Make the Rocket

All you need is cardstock, tape and scissors.

It's easy to build a rocket that can reach a distance of 50 feet. However, making an ultra-high-performing rocket is actually quite challenging because all aspects need to be designed to near perfection. At high speeds, tiny imperfections are quickly blown out of proportion because the forces acting upon the rocket are intensified. For example, a nosecone that leans slightly to one side may not significantly influence the rocket's performance at 40psi, however at 60psi that nosecone may create an imbalance of friction created by the air rushing by, causing the rocket to turn sharply and tumble to the ground.

For this reason, take your time while creating & attaching each part of the rocket. And with that in mind, here's how to make a high-performing rocket:

Step 4: How the Valve System Works

Step 5: Safety, Tips, and Troubleshooting

Follow these safety precautions regardless of whether the chamber is pressurized or loaded with a rocket.

  • Never allow students to use the launcher unsupervised. Disable the launcher by removing the battery (or pump or launch tube) if you have to leave the launcher unsupervised.
  • Never allow anyone to put their face near the launch tube. Air expelled from the tube, if forced into someone's nose or mouth, is powerful enough to cause the lungs to rupture. This is very serious. Tell your students about this and they will be frightened enough to never get near the tip of the launch tube.
  • Never stand directly in front of the launcher, even if a rocket is not loaded. At point blank, a rocket shot from the launcher can cause serious injury.
  • The student holding the button should keep his/her trigger finger off of the button until the final countdown is initiated. The button is sensitive and can easily misfire.
  • Use a bright rope to define a safety zone that the students may never cross, even while loading their rocket.
  • Have a countdown before each launch as a way to alert people in the area (and to make each launch more exciting!)

Common design flaws

  • Fins that are not attached straight, or the leading tip of the fin is not secured, will cause the rocket to tumble at high speeds.
  • Fins that are too big create too much lift and/or drag.
  • Fins that are too small may not provide enough stability.
  • Fins that extend too far from the fuselage are prone to wobbling in the wind, causing instability.
  • Nosecones that are not secured well enough will explode off of the rocket.

Tips and troubleshooting

  • Rockets tend to explode at pressures above 60psi. If you choose to mod the button with a second 9V battery, have the students tape up every seam many times over.
  • Inspect the rocket before each flight and use your hands to straighten out the fins and nosecone, which will inevitably become bent over time.
  • I usually refrain from interfering with students' designs, however if a student has created a poorly built fuselage I will step in and help them. Making a new fuselage after attaching everything else can be a hassle.
  • Young students (grades 3 and below) may have a hard time rolling a tube of cardstock, so I usually do that step as part of my prep.
  • If you don't have access to a huge open space, you can set up targets like stacked cardboard boxes and aim for those. Be extra cautious here.
  • When storing the launcher, remove the 9V battery, or at least make sure the button is uncompressed or else the battery will quickly drain.
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70 Discussions

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NoahH50

Question 10 months ago

So I purchased a build it yourself kit from Its a blast, got a confirmation invoice. I went to find their number cause it has almost been a month and their website is down. Anyone have their number?

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dndonofrio

10 months ago

Would love to do this...how do I go about purchasing all materials?

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LanceMakesCats Science Club

Reply 1 year ago

Yes! 1/2" PVC pipe fits perfected through the neck of most standard plastic bottles.

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Masher007RDmaniac

Reply 1 year ago

They use metal tanks, from aluminum or steel fire extinguishers, to regular pressure cylinders. As cheap as PVC and Safer.

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Masher007RDmaniac

Reply 3 years ago on Introduction

No PVC, ABS, CPVC or plastic should ever be used. The cycling to pressure, down to zero, up to pressure, back to zero, makes it fail. It is unsafe to pressure test with air even when new. HDPE can be used, but it has to heat welded, and it cannot be glued. There are lots of metal choices. CO2 tanks, paintball tanks, retired medical or industrial gas cylinders, that used to handle pressures of thousands of pounds, can handle 100 PSI indefinitely. Empty fire extinguishers. Even empty propane tanks and bottles, are designed for pressure, and cycling, up to 250 PSI. One does have to watch for rust or corrosion with disposable tanks, as they are intended to be thrown away before they can rust through. Pressure vessels are also designed to split and vent when do fail, without any risk of shrapnel.

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Goodluck

2 years ago

Oh, one more thing i thought of after builing: if the launch tube were made about 5 feet long, only adults would be able to get their eyes/head above it. Of course that would probably reduce range.

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MikeB46

3 years ago on Introduction

Some safety suggestions.

Fiber reinforced packing tape instead of duct tape wrapped around all the PVC parts. The fiberglass reinforcing threads are stronger that the fiber backing in duct tape and is much more likely to contain any loose parts. Make sure to tape around every pressurized part including lengthwise and around for all the piping. Still, having the whole thing inside a strong cloth bag would be safer still.

Not only use a second arming switch in series with the fire switch, but put it on a second cord and only let the adult supervising the launch have it. Lights and buzzers or alarms are a great addition. Even inside a burlap sack a string of red LEDs along the storage pipe and launcher would look good and alert everyone to be extra careful.

Add an extra 'T' fitting between the storage tube and the valve. Add a 3/4" male thread to it. Using 1" tubing make a short "T" handle about 6" across and 6" upright. You should be able to glue the 1" tubing at the bottom of the T around the 3/4" cap piece. Now you have a removable safety plug. If you have to leave the launcher, the handle should make it easy to unscrew the cap piece and now it is impossible to build pressure in the launcher or fire off a rocket. If already pressurized make the first turn slowly to bleed the pressure off. You may need to rubber gasket to improve the seal. A water house gasket might fit.

If you are willing to spend an extra $14, amazon among many other places sells an adjustable air pressure relief valve. Add that to the pressurized portion of the launcher and then even if a kid gets over enthusiastic and tries to pump past the limit it will simply vent the extra. Most also can be manually actuated to safely depressurize the launcher without pressing the fire button.

I have played with one of these but not yet made one. I would like to add it to my list of fun toys.

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hi , so i put everything together and have a problem the valve seems to release very slow. No sudden burst of air to shoot a rocket off. Is it a bad valve?

1 reply

I might end up doing this with lower pressures, like 10-20 psi and nerf darts to make a rifle. At that pressure would it be safe to use a ball valve?

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makeminefun

4 years ago on Introduction

Our Scout group had one of these lying around, which I very happily inherited and started playing with immediately. Of course, I tried to break it, which I did.

I have to agree with DanTDM and Masher007 -- and many thanks for the warnings; this can explode and potentially hurt bystanders or operators.

The device that failed on me was a couple of years old, and worked well until I pushed it past 40psi. Then then end cap blew off and sent shrapnel 40-50'. Thankfully I had laid a thick wool Scout blanket over the unit, so neither me nor my 3 year old son standing nearby were hurt.

I was operating the device in about 10 degrees Celsius (50 F) and had successfully launched it about a dozen times with 40psi charges, which resulted in flights over 200 feet.

So, be careful. Wrap the device in a heavy blanket or a shield that will contain any potential shrapnel. I really don't think duct tape is sufficient; it can fail too. This is especially important if the device is a few years old. It was the pipe cap that failed, not the glue, and I think the point of failure was where the inflating nozzle entered the cap; i.e., the hole that was drilled weakened the integrity of the PVC pipe cap.

A future improvement might be to add a gasket on the inside of the cap with the nozzle so that there is more support around the weak point.

Super fun project when it works, potentially very not fun when it fails. Take precautions and be dangerous safely.

IMG_20141102_171254.jpg

The rockets are pretty easy to see in real life, though it's really quite challenging to capture a paper rocket on video. Streamers might look fun, but I think it would create too much drag. Perhaps a longer rocket would be more visible (and fun!)