How do superheroes fly?

Superman. Superman can alter his personal mono-directional gravity field to propel himself through the air at will due to the gravitational pull of the Earth being less than that of Krypton. This basically means that he can manipulate the effect of gravity on him. read more

Here's what Wikipedia has to offer on the subject of Iron Man's flying suit: > The defining abilities of Stark's armor are the jets situated in the boots and the repulsors situated in the gauntlets. read more

Having been exposed to "lethal" doses of cosmic radiation, Johnny (of course) develops formidable superpowers, just like the Hulk. He can fly, so as with Superman, we hypothesize that he forcibly expels gas at high velocities in the appropriate directions. read more