How are flying objects propelled?

Something I've noticed is that you have this question in the "UFOs" section. With that being said; A UFO most likely has a less dense metal around the exterior of it, and probably the interior also.

Do I believe in "UFOs" and "other exterrestrials living amongst us?" The answer is yes!

Pertaining to the question, air resistance plays a BIG role in the "propelled" process.

I could babble all day about this question, so I will just leave it be.