Would a Dragon Actually Fly?

Flying "dragons" exist today and in the fossil record. They are not merely fantasy beasts. While wingless dragons wouldn't fly in the strict sense of the term, they could glide long distances without violating any laws of physics. Fire-breathing is unknown in the animal kingdom, but is theoretically possible.

What is a dragon that can't fly?

Size and weight. Most fantasy-dragons are giant beasts, which would make them unable to fly by their weight alone. The biggest known animal to fly is the pterosaur Quetzalcoatlus which may had a wingspan of 12 m, but since the wings make up the majority of the body, it was very lightweight (100-200kg).

Is a dragon physically possible?

"Yes. But the operative word is 'might'." A potential process could involve modifications to an existing large reptile - for instance, a Komodo dragon. ... The first issue could make the animals overheat; the second might mean the edited reptile's bones would be too weak to hold its weight.