[nitwit005]

People did genuinely struggle to define "useful flying machine", which is why you see the description of the Wright Brother's flight come with so much detail: "first controlled, sustained flight of a powered airplane".

[xanderlewis]

> or at least it's easily possible to come up with a good definition.

[nitwit005]

That's my point. It wasn't easy. There are still disputes over flight achievements because people don't agree what should count.