The first few posts in this thread remind me of the story of the man who goes into a clothing shop to buy a coat.
Shop Assistant: “Good morning sir, can I help you?”
Man: “Good morning. Yes please I would like to buy one of those hooded jackets. I want it in red and it must be the smallest size you have”
Shop Assistant: Oh no sir. The blue ones would suit you much better and you will need the large size….or if I may say so, perhaps the extra large.”
Man: “No thank you I want a small red one.”
Shop Assistant: But sir, if I sell you the small red one I will be wasting your time and mine. You will be coming back tomorrow to swap it for a large blue one.”
Man: I want a small red one. It’s for my daughter who is starring in the school play….Little Red Riding Hood.”
In the case of this thread there are also a couple of posts which effectively have the shop assistant saying “why don’t you just stop being so lazy and go away and make your own coat?”
Having observed the way the thread was developing I was tempted to give the answer which the OP had requested. I knew from previous experience that this would cause me to be met by a crowd of people who would inevitably conclude that I must be a supporter of the Bernoulli explanation and they would by eager to demonstrate their superior knowledge. In an (unsuccessful) attempt to avoid this tedium I included the following comments in my post:
There are a great many different ways of explaining how wings create lift. As some of the above posts have revealed, the Bernoulli method is not universally accepted as being true. But you have asked the question:
Quote:
"Why does increasing AoA (up to the crit AoA) increase CL?" Please keep it in relation to Bernoulli's theorem
So I will give you an answer to that specific question.
And
As I have said earlier in this post, the above arguments are not universally accepted, and it is very easy to pick holes in them. But I will leave that task to others who would prefer to show you how clever they are rather than attempting to help you.
And in a later post:
I am not going to waste my time attempting to defend the Bernoulli explanation for lift, because I am well aware of its faults and some of the alternative explanations and theories.
Sadly all of those comments were ignored and, as expected a number of posters have set about convincing me that I and Bernoulli are wrong.
Well here is a news flash folks:
1. I have never argued that the Bernoulli explanation is correct.
2. I do not believe that the Bernoulli explanation is correct.
3. You do not need to waste your time and mine by attempting to convince me that
the Bernoulli explanation is wrong (see note 2 to understand why.).
But just to keep the thread going:
Bernoulli knew nothing of aircraft - they were before his time. His ideas are related to fluid flow, and yes, air is a fluid. However, his theory when, applied to airfoil lift, does not correctly explain why a wing develops lift.
That is true. It is also true that Newton knew nothing about space flight but his laws of motion are used everyday in designing and operating spacecraft. Bernoulli’s Theorem is based on the laws of conservation of energy. These laws apply to aircraft just as much as they do to anything else. But of course this does not make the Bernoulli explanation of lift correct.
However it made one very good point which was In order to explain the complicated truth it is sometimes better to use a simple lie
In other words trying explain lift correctly was not easy to explain nor understand whereas the Bernoulli theory did the job well enough to explain what happened so far as a wing (or any aerofoil section) generating lift.
Absolutely correct.
Keith, the mindfulness of the air molecules was just an attempt to simplify that the theory that an air molecule above the wing has to speed up in order to arrive at the trailing edge at the same time as an air molecule below the wing is completely fallacious. What I meant was, air molecules only know about the proximity of nearby molecules, and all basic physics can be explained on that basis.
Although you appear to have modified your views on the “awareness” capabilities of air molecules, you are still wrong. Air molecules have no awareness of events whatsoever, regardless of whether the events are close at hand or far aware. The movements of the molecules are determined by the forces acting upon them. Nothing more, nothing less. In using your “awareness” concept to explain things you are using a lie to simplify your explanation, in the same way that anyone using the “long path/short path” explanation of lift is using a lie to simplify their explanation. The use of such lies does make things easier simply because it eliminates the need for much of the explanation.