We have a factory that makes those small plastic signs that you see in people's front yard at election time. We have a pyramid sized mountain of leftovers that we wanted something to use it for. What better than to build a full size airplane with leftovers, a hit glue gun, washing line, and some wheelbarrow wheels?
We designed it with 5 napkins and a 12 pack of beer.
Our only rule was that it had to be plastic. We build the entire airplane out of leftover plastic, used PVC plumbing for the controls, plastic washing line for the rigging, and covered it with clear vinyl.
We got a local racing car company to sponsor pay for the engine, and went to fly it at the local airport with me as the guinea pig.
Step 1: Step 1. Design
I'm a pilot so I know basic aeronautical engineering (classy speak for what shape airplanes should be). Using that knowledge we designed the parts on some napkins over a few beers.
The hardest part to envision was the control systems to make it a full 3 axis airplane, with roll, pitch, and yaw, for which we needed aerilons, elevators and a rudder.
I came up with how to do it while I was actually in the shower not thinking about it. I built a full gimball system for the control stick out of 1 inch PVC pipe, using standard fittings from Home Depot to create a universal joint.
The joints that were solid were glued, and the joints that were meant to rotate were not glued.
Step 2: Wings
Once we had figured out the basic idea we just had to design an airfoil for the wings. I searched around on the internet to find a good slow speed airfoil. We scaled it up to 4 feet long (to use up the leftover pieces of plastic) and used the router table to cut out about 50 of them. We slid these onto box spars also made out of leftover plastic and hot glued them in place.
One we have wing shapes we covered the leading edge and training edges in more plastic to strengthen it up.
The airfoil sections had to be leaned over slightly to create dihedral when we stood the whole thing up.
Then we made 4 main attachment spars by laminating multiple sheets of the plastic together. These just plugged into the spars on the wings.