Ornithopter: A machine that flies by flapping its wings. Seriously, it’s a thing. Ornithopter.org claims the first successful flight was made in 1942. To do it with mainstream technology such as drive-belts and cams is difficult. To really fly like a bird, you need muscles like a bird. Synthetic muscles are just emerging, although this Popular Mechanics article shows how they can be made from simple monofilament fishing line. We might get there yet.
Tech Level: This is tricky. Flapping wings have been tried for centuries, and they’re only just beginning to work now. Not an easy fit for Near Future SF or Dieselpunk, they might be more at home in something with more of an Alien Worlds vibe.
Appeared In: Dune, by Frank Herbert. Ornithopters were in the book but not the movie, because even if you get the computer animation right, it still looks so weird that people won’t believe it.
For Your Plot: I think Mr. Herbert did it because he wanted Arrakis to look regressive and technologically divergent. For something completely different, we could go back in time and build a fake fire-breathing dragon and take over some nice castles. Better yet, let’s have a woman do it, and stand all that damsel in a tower stuff on its head.