When I get a new student for a TIF I
ALWAYS make them a cup of tea or coffee first and get them chatting while the kettle boils. I have a big spoon in the kitchen for just this purpose.
The point of it is that the laminar flow accross the back of the spoon causes the water to deflect , the same way as the wing causes downwash at the trailing edge. Newton's Third will have it that every action has an equal and opposite reaction.... and so the spoon deflects the water,
and the water pushes the spoon.
Similarly, the wing forces the airflow downwards... and the downwash pushes the wing up.
It is useful for explaining ground effect and also for demonstrating the separation point and loss of lift in the stall.
Having a brain fart and can't remember for the life of me what its called
