Previous puzzle of this kind: #1
A bird without wing, body, feet or tail,
An invention am I who can effortlessly sail.
I am unlike my lowly brothers who only deliver mail;
Surging over the winds I am majestic without fail!
...Alas, that is a lie, I do have one shortcoming
In order to be useful to you I cannot be made thin.
Thanks a lot, you, you darned and cursed thing!
Now there are barriers I shan't break, oh, races I'll never win!
You say that there's a Wikipedia article for anything?
Find mine, then, and declare yourself this puzzle's king!
My stability was an issue that my creators did see
That is the reason why they taught me to sweep.
UFOs have a generic shape;
I do too, though not from space