Introduction: Cardboard Rocket - It Flies!
This project is the product of a collaboration with a friend of mine somewhat obsessed with rocket propulsion. We wanted to make something simple (made from little more than cardboard and duct tape) that could do something cool.
This Instructable provides the cut sheets for use with a laser cutter, precision cardboard cutter, or you and your choice of cutting implement(s). If you follow it through, you'll have something launchable!
Step 1: Gather Materials
- cardboard salvaged from shipping boxes
- duct tape
- drinking straw
- cardboard cutting and assembly supplies (Xacto blade, scissors, cutting mat, tacky glue, two straight/safety pins)
- small hobby rocket engine (we used an Estes A10-3T)
- cladding for engine (usually included with the engine)
Optional: model rocket launch pad and controller, laser cutter
Step 2: Model the Rocket
Step 3 contains the patterns for the final pieces to cut from cardboard.
If you want to design your own rocket rather than use ours, use your favorite 3D modeling software (we chose SolidWorks for this project) to model a simple rocket.
We wanted to use the 123D Make web app (see step 3), which can produce the patterns for either folded paper or stacked cardboard (rather than more skeletal, interlocking pieces; that can be done through the desktop app). This meant that the body and fins needed to be separated in the virtual model and will be assembled in cardboard form. The notches in the body are made to accommodate the fins, which are formed in two segments that slot together.
Step 3: Make the Rocket From Cardboard
We used 123D Make to create patterns for the cardboard rocket using the process described in this Instructable. Follow all of the instructions there (with slight modifications/clarifications here) to assemble the rocket.
Note that I learned my lesson and used a laser cutter this time around.
It does not matter if the cardboard you use for the rocket is unattractive or colored (ours was salvaged from a recycling bin), as it will soon be covered by duct tape.
Use the .pdf files included in this Instructable to pattern your cardboard shapes (attached on this step).
I strongly recommend printing a copy of the pattern used in the laser cutter if you are not cutting by hand, and arranging the cut pieces on top of that sheet.
The fins may need to be altered for best fit, because the patterns are designed for 'standard' cardboard. Yours may be thinner, meaning the connections and notches of the fins are too tall. They should be flush with the four-piece layer. We cut ours by hand as shown. Slot the fins into the notches in the body before completing assembly of the body.
Step 4: Robustify the Rocket
Rockets are usually made from things stronger than cardboard (namely, aluminum, titanium, and steel). We figured we should at least add some duct tape.
Begin by adding a strip of duct tape wide enough to cover the edges of two adjacent fins. Crease this carefully to hold the fins in place. Repeat for all four segments.
Cover the fins with tape one side at a time, overlapping carefully on the edges. Too much overlap will add bulk that will keep the rocket from reaching its full potential.
Cover the body of the rocket with "rings" of tape until you reach the nose cone.
Get creative with the nose cone tape cover. We used very thin strips of tape that culminated in a bunched-up tip. You could try making a folded cone shape from the tape, criss-crossing...whatever seems reasonable to you. It doesn't hurt to add a bit of mass to the nose cone, but don't go overboard.
Step 5: Give the Rocket Some Fire
We selected an A10-3T model rocket engine because it was readily available and generally suited our purposes.
Crumple one piece of cladding (usually included with the engine) and insert it into the bottom of the rocket (the section with the holes cut in the cardboard layers). Push it in as far as possible.
Insert the engine and tape it into place as shown.
Some model rocket engine notation:
The 10 indicates the expected average thrust in Newtons.
The 3 after the dash indicates a three-second ejection charge delay. Because we're okay with this rocket tumbling to the ground, it does not have a parachute and the ejection charge is mitigated by cladding added the top of the engine.
The T at the end indicates that it is a “mini” engine, meaning its external diameter is 13mm.
One of the advantages to using this engine is that the rocket won’t gain much altitude -- a few hundred feet at most -- but will be slow and easy to follow. The low altitude means that it can be launched from almost anywhere, and wind will not seriously affect recovery, so amateur rocketeers won’t have to worry about finding a big open field to launch the rocket.
For those new to model rocketry, we recommend a 1/2A3-2T model rocket engine.
The 1/2A indicates an engine with half the power of an “A” size engine. At this scale, that generally means an object attached to it will fly about half as high. This engine is also small enough that it doesn’t roar as it takes off, which makes it a great starter for those who might be frightened by a loud engine sound. This one produces more of a “pfft”.
Step 6: Prepare for Launch
Cut a 1.5-2" segment of the drinking straw and tape it to the side of the rocket. This will be used to guide the rocket onto and along the launch pad rod during launch.
Step 7: Send It Off!
Recruit a friend and head out to a field.
Set up your launch pad a safe distance from people, buildings, trees, and the like.
Put the rocket onto the launch pad rod using the straw and connect the controller leads to the engine and igniter.
Move a safe distance from the launch pad with the controller, count down, and watch it go!
Ours has survived two 200-foot launches so far, even with a bounce landing!