Paper Airplane Crossbow

In this project I developed a cross bow that shoots paper airplanes. I have made several crossbow based designs because I find the use of springs and rubber bands in projects interesting. I used Fusion 360 to design it and a Kobra 2 to 3d print it out of Grey PLA. I currently attend the University of Kentucky as a sophomore of mechanical engineering.

For this project you will need:

• 2 - m1 screws
• 1 - 1/8th inch rod(can be cut from wire coat hanger)
• 2-3 - rubber bands
• 1 - 3D printer
• ~80g of PLA
• 1 - pen spring
• 1 - hot glue gun
• 1 - sheet of white paper
• STL Files Provided or Fusion File

First you're going to want to 3D print out the files provided with this project. I used an Anycubic Kobra 2, but any 3D printer should work as long as it has a 250mm build area. I printed with normal supports on, and with this model it is preferred to not have a brim to reduce post processing time. Next take them off of the printer and remove any supports you find across its body.

Now that the pieces are cleaned up attach the handle to the corresponding hole in the back of the main body(if you have stability issues try adding a 1/8th inch brass rod through the hole between the handle piece and the main body).

Next, attach a small compression spring (usually found in old pens and mechanical pencils) to the rear of the handle piece. While that dries insert 2 M1 screws into the post holes in the handle, with enough space left for the trigger mechanism. Alternatively you could find a small steel dowel, or another sturdy piece with ~1mm diameter so that it will fit in this hole.

The thrust of this project can be given by normal rubber bands or a large hair-tie, for my purposes I used 3 normal sized rubber bands two looped through the side holes and another in the center holding them together. Now you have a finished bow.

As for the airplane to be shot I have found that you can use a normal white sheet of paper, folding it in half, making it a 5.5in by 8 inch piece. You can then fold it into the basic dart style that there are other articles on how to make. Alternatively I have attached a file I also designed in fusion that can be 3D printed.

*This launcher can output quite a bit of force if you wind the rubber bands so make sure to fold the tip of the plane back to reduce the potential danger, also if the rubber band crumples the back of the plane apply some masking tape to the back to increase stiffness.