Rockets Some of these debates are quite fascinating and all personally I do believe there is a useful distinction to be made between objects that move through the air purely driven by momentum unpowered projectiles or by altitude loss gliders parachutes free falling objects or by movement of the fluid though which they fly kites free blowing objects in updrafts and objects that truly fly but I think a critical deficiency of the article has been over looked The introduction s definition of flight as the process by which an object achieves sustained movement through the air by aerodynamically generating lift or aerostatically using buoyancy completely overlooks objects that fly within the earth s atmosphere by expelling gas and using the resulting opposite reaction A rocket achieves sustained powered true flight by any reasonable standard yet it makes use of neither aerodynamics nor buoyancy I m not quite sure how to reword the sentence to include rockets Any suggestions