Let's say I want to build an aeroplane completely from scratch (not downloading some blueprints on the internet, I mean really designing it myself). The goal is to create a flyable aeroplane from scratch, that can safely fly.
What would I have to take into consideration and where are good resources for it? I don't want to depend on a wrong formula, and have the wing break off the aeroplane in mid-flight, because there was an error in the equation. So what resources are free (or cheap) and trustworthy?
I know, that the aeroplane should be reasonably aerodynamic and the wings should create lift. How do you test it, when you don't have a wind tunnel?
How can you compute the necessary wingspan and wing area and how do you test and analyze your design? They don't have to be that big, as you can see with the "jetman", who has a relatively small wing strapped to his back.
What programs would you use to run simulations? Are there free alternatives, that could be used instead and are they any good?
The design phase shouldn't cost much, except time. However, if there have to be certain precautions taken that cost something, that's OK.
What materials should be used (fiberglass, wood, carbon fiber, metal)?
How do I get the proof of airworthiness (on a design)? After this is done, I might actually go and build it myself.