> You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit.
I've never hear of a good mental model built on Bernoulli's Principle. They are either:
- Wrong
- Give no intuition
The key question is /why/ air moves faster on one side, and once you get away from the misconception of same time, I've never heard an intuitive argument.
Redirecting air down:
- makes complete sense
- can be demonstrated by sticking your hand out the window of a car
- works with flat airfoils (sails, kites, etc.), and explains those well too
And the shape of the wing comes in from wanting the leading edge parallel to incoming airflow, and the other edge parallel to outgoing airflow. On a sail, I can adjust the shape. On a steel wing, I can't much, so I make a shape which works across different angles of attack.
All of the other mechanisms, you can gradually work in from there to get accurate models. Toss in air moving to the low-pressure area, and having momentum, and you get why helicopters are less efficient than planes, as well as vortex shedding. It all builds up.
As a corollary, Bernoulli tells you where air moves faster, but that follows from lift. Not the other way around. At least in any model which fits the human brain.
I've never hear of a good mental model built on Bernoulli's Principle. They are either:
- Wrong
- Give no intuition
The key question is /why/ air moves faster on one side, and once you get away from the misconception of same time, I've never heard an intuitive argument.
Redirecting air down:
- makes complete sense
- can be demonstrated by sticking your hand out the window of a car
- works with flat airfoils (sails, kites, etc.), and explains those well too
And the shape of the wing comes in from wanting the leading edge parallel to incoming airflow, and the other edge parallel to outgoing airflow. On a sail, I can adjust the shape. On a steel wing, I can't much, so I make a shape which works across different angles of attack.
All of the other mechanisms, you can gradually work in from there to get accurate models. Toss in air moving to the low-pressure area, and having momentum, and you get why helicopters are less efficient than planes, as well as vortex shedding. It all builds up.
As a corollary, Bernoulli tells you where air moves faster, but that follows from lift. Not the other way around. At least in any model which fits the human brain.