Sayu says: MB: The Balrog might have had wings, but as given in the movie there was clearly no way for him to safely expand them in that very narrow shaft. If anything, it might have increased the (cross sectional) surface area slightly, but not nearly as much as full extension. Modeling it with a sphere is accurate enough anyway, it's all a question of the correct radius of that sphere, which may not be the size of the balrog. Of course, looking at the actual footage, I might be wrong on the first point, but I came up with a simple solution to the problem: you can watch the Balrog falling objectively in the few seconds from 3:15 to about 3:19/3:20. In about a second, the tiny looking flaming ball covers slightly more than its own diameter in distance in what we presume is a directly downward direction. I'm going to estimate from shots around that time period that the balrog, and therefore the balrog's fireball, is about 2.5-3x the hight of Ian McKellin, whom I assume to be somewhere in the order of 6', or about 2m. Therefore, it is falling at about 5-6 meters per second at terminal velocity. I know that doesn't sound right (a skydiver goes about 60), but let me do the math anyway. In that case, the balrog reaches terminal velocity in .6 seconds (3.53 feet), and falls at 6 meters per second for 103.4 seconds. In other words, the distance is d=3.53 + 6*103.4 + 0 * t * t = 623.9 meters. Which is almost undoubtedly wrong, but is much more acceptable than 100km, I guess. So no, still no real answer.