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.
First, they are used as parachites
Ornithopter
Unidentified Flying Objects are objects which we are, by definition, unable to identify, and thus we will have no idea as to how they are able to fly.
Unidentied Flying Objects are UFOs.
Yes, friction can stop objects from flying . . . unless the objects are moved by something stronger than the friction.
The initials for unidentified flying objects are UFO.
Unidentified Flying Objects The True Story of Flying Saucers - 1956 is rated/received certificates of: USA:Approved (certificate #17778)
A rocket propelled winged UAV (a winged flying bomb); (UAV-Unmanned Aerial Vehicle).
Unidentified Flying Objects.
unidentified flying objects
James E. McDonald has written: 'Unidentified flying objects' -- subject(s): Unidentified flying objects
A plane, bird, rocket, frisbee, in fact anything that is propelled on a trajectory in air can be considered to be flying.