I'm having a bit of a mental block, and would appreciate some physics help here. I feel like I should know this, but am missing something obvious. If I want to levitate a 70-kg person off the ground, the amount of Force required to lift them is easy to calculate: 70kg * 9.8 m/s^2 = 686N. So far so good. Now, to calculate the amount of Energy needed to move the person upwards by 1m is 686N * 1m = 686J. Ok, now we've got him floating a meter above the ground. Except that he's not just going to float there indefinitely unless 686N of force is applied to him, to counteract the force of gravity. How do I figure out how much Power (i.e. constant input of Energy) is required to keep him floating there? Power (thrust) is defined in terms of velocity or distance displaced, and since he's just sitting levitating, not moving, I'm not sure how to calculate that. Someone please help me out. For someone rather well versed in science, this is both frustrating and slightly embarrassing not to be able to figure this out.