Quote:
For example, if you put a box with an upward-facing propeller on a postage scale, the box would weigh less when the propeller was turning since at least some of the air pushed downwards by the propeller would not hit the weighing surface of the scale.
Okay, so let's take that same concept and make it a bit more clear...
I have a radio controlled helicopter, and it's sitting on a very accurate scale with a very large "plate" on top (or whatever they call the bit you sit things on). The plate is much larger than the helicopter, large enough so that the downwash from its props will definitely hit it.
I hover the helicopter 1cm over the center of the scale. Is the weight registered on the scale exactly the same as the weight when the copter is landed?
If not, how is that different than a parakeet flapping its wings in the cargo hold (assuming the cargo hold is not pressurized)?
Previous Topic
Index
