It's a shame that someone so dedicated to their passions had to die young.

Did he spend any time modeling the physics of a helicopter control system? It would have to be of the most complex control systems to model. You don't just build a helicopter. Maybe he should have begun by building a scaled-down version instead. Maybe he did all of this due diligence, and just overlooked some unfortunate minor detail. Some of the comments here are blaming materials failure.