The Tethered Electric Airplane is an aeronautical design project for high-school aged students. It was developed by Jason Brett and Todd Ablett as students in the BCIT Technology Teacher Education program and refined and expanded by many other teachers and students over the past 25 years. This post contains links to relevant documentation and starting points for teachers (or others) wanting to explore similar paths.
I have a three video playlist on Youtube explaining the project and how to build some of the equipment required to run it with your students.
The project requires a small DC motor for each plane, wound for using the high voltages (20-30V) of a bench power supply rather than the high currents provided by a battery. While you will likely find a better deal on motors at your Local Electronics Shop, my reference motor, available at the click of a button is available here, from Pitsco.
There are a few documents available to plan the project and use with your class. The first is the “Teacher’s Guide” and discusses some of the materials and lesson planning concerns. It uses the NASA FoilSim engine to help students design an airfoil cross-section. FoilSim is now referred to as “Student Airfoil Interactive” — Thanks for bringing that back from the Javascript Graveyard, NASA!! 🙂
The next is a shortened version of the document, that can be used as a handout, to guide students through using FoilSim to design an airfoil cross section.
For a more advanced class, it is possible to use real, wind-tunnel tested airfoil to select an airfoil cross section. This document has information on using the Airfoil Tools database to select an airfoil.
I have recently added some 3D printed elements to the challenge. These files should allow you to print an engine mount/fuselage and tail section that will press-fit to a dowel (or even a long pencil) to form an airplane. I have shared the files to Thingiverse.
For designing multi-blade props from scratch you can use a parametric modelling program such as Fusion 360, but OpenSCAD has an algorithmic process available for creating them. Check it out!!
I have also been playing with more advanced aerodynamic finite element analysis simulation for modelling airflow over the plane in a virtual wind tunnel environment. SimScale looks promising! For a simpler, more interactive view of flow over an airfoil consider phone/tablet apps such as Wind Tunnel Free.
Every time I search the Google Play store for “airfoil” I find new apps… “Airfoil Design”, “Airfoil Analysis”, “Joukowski Simulator”, and “Aerodynamics Thin Airfoil” all look promising, but I haven’t tried them yet.
And since you’ve read this far, here’s a few photos to fill up the rest of the web page!
Good luck, have fun, and remember to wear eye protection whenever the prop is spun up!
Oh, and in case you were wondering… “Pusher Prop” designs don’t work well as having the thrust at the back tends to magnify any angle of attack errors, and twin engine designs might look beautiful, but still have to share the power coming from one power supply… hook them up in series and you get twice the resistance, and thus only half the power coming to your plane! But they can be made to work if the students put enough effort into it!
Building Robots at School 