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This actually makes much more sense to me as the actual distance across the front and back sides of the sail cloth are but that layer of cloth different, not at all like the wing of an airplane which actually has a distance difference.
Lift does not require a curved surface, nor even a difference in distance over the two sides of the foil. If it did, planes would not be able to fly upside-down.

"A flat plate can generate lift, but not as much as a streamlined airfoil, and with somewhat higher drag." ... as long as there is an angle of attack.

https://en.wikipedia.org/?title=Lift_(force)
 

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This kinda reminds me of the time I was riding in a car with a software engineer, and a quality control manager. As we we were coming down a hill the brakes failed.
Only by the grace of Poseidon or Zeus or Neptune did we safely reach the bottom. The quality control manager wanted to take apart the brake system, measure all the components and run metallurgic analysis to determine the failure. I being the mechanical engineer wanted to check the fluid level and pad thickness. The software engineer wanted to push the car back up the hill and try again to see if it failed. ;)
That's funny, I was on that same car ride and remember there was a manager with us. After the near miss we couldn't do anything because he called us into a meeting for a couple hours to discuss the situation.
 

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Quirky
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In all honesty, engineers aren't typically considered to be people persons and they do love their details. A pediatrician and an ER doc don't get as detailed in their jobs and spend about 5 minutes at a time on a patient (usually).

So you have an extraordinary detailed person teaching a couple of doctors who likely have some ADD. All three are intelligent people but perhaps there's a conflict in teaching and learning styles.

People will start with the details first when explaining something and get frustrated when the other person stands there with their mouth open. But they aren't explaining things in the best way for the other person to learn. Adults process new information better when given a more generalized description before going into the details. Paint with a broad brush then switch to detailing. I'm harping on the teaching because the "teacher" had two "students" and neither of them were understanding things. So perhaps it was the teacher?

I've got some sort of grasp on it, but if someone started off with specific fluid dynamics, laminar flow, etc then my eyes would glaze over while thinking "Where are they going with this?"

Just my two cents. Spend it wisely.
 

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Lift does not require a curved surface, nor even a difference in distance over the two sides of the foil. If it did, planes would not be able to fly upside-down.

"A flat plate can generate lift, but not as much as a streamlined airfoil, and with somewhat higher drag." ... as long as there is an angle of attack.

https://en.wikipedia.org/?title=Lift_(force)
Very Good analogy but only part one of 2 parts.
Part 1: Bernoulli Effect of the lee-side of the plate, sail, foil, etc.
Part 2: Newtons 3rd Law - action versus equal reaction (boat)

Combine 1 & 2 together and you have the 'pumpkin seed effect': ... pushing your index finger (sails - at a slightly non-aligned angle ... AOA) against a slippery pumpkin seed on top of your thumb (lateral resistance - or CLR) = 'squirt'.

;-)
 

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Quirky
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I'm totally screwed. I went to engineering school before med school. Wife's amazed I can get through a day.


I know an ER doc that started out as an engineer.
He too somehow manages.
 

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navigator
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From my experience in many years of civil engineering school and graduate work in the same, plus management and finance, my observations were that just because you had a degree in something or advanced degrees in something, did not make you a teacher of said subjects.

My general theory is that if you are brilliant in a subject or a profession, you may not have the ability to explain the subject matter to persons of lesser intellectual capabilities. Many of my most effective teachers in life were not PHDs or the like; but people who had the god given talent to explain something to someone.

Once had a physics prof for second semester physics, electromagnetism or some such nonsense. He had previously only taught PHD candidates. Most of us were civil majors (electricity and electromagnetism, what the hell was he talking about). He could not relate to us "dummies", or explain the concepts very well at our level. Eighty students started the class, about 20 of us finished: one A, two Bs, a couple of Cs, the rest Ds and Fs. I squeaked through with a D, so I passed. The only class in high school or college that I knew more at the start of the semester, and after taking the final...or was that differential equations.
 
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