Originally Posted by
slipped
I always thought of it like this:
Think of a blade going through water. if the blade is feathered eg slicing sharp through the water there is little drag, a wing is very similar.
A wing slicing through the air at a low AOA creates little drag AND little lift.
When you increase the AOA to get more lift the knife/wing is harder to move through the water= Induced drag
That is how I thought of it too. Easy to understand/visualize that way, however none of the literature seem to support it. They're always talking about vortices and downwash and bending the lift vector blah blah.
I agree that that concept is simple to grasp and understand. Your hand out of the window of a car.... hand flat no lift not much drag....tilt hand arm goes up and back.....lots of lift and lots of drag....muscle (thrust)needed to keep arm from moving back, but arm otherwise floats.
This example demonstrates something about aerodynamics, but I dont think it really is induced drag (wish it was, then I could say i understand induced drag)
Now, I would like to understand what we just described if it is not induced drag??