Flying vecicle like airplane. You need to achieve a certain speed for take off.
I'm not overly familiar with copyright law, but at the very least it seems ill advised to blatantly take content from other games, especially since you're distributing it with an open source license.
It's a mod, A copyright issue would only happen if the vanilla game uses it
It uses assets the author of the mod created. Nothing was "stolen" apart from the inspiration of the appearance and the name, and thus it falls under "fair use".