I thought this might be a good video for those of us that understand the "what" of all of this but don't have the scientific or math background to "go into the weeds" and totally understand the why.  It also helps me understand why we have such a difficult time in defining the "perfect" airfoil and where to put the trip strips!  If any of you that *can* and do get into the weeds find this to be BS, please point it out.

I am deleting the link after being informed by two respected members of the forum that know far more than I about these things.  Bye link, see you around.

Ken

That is what I was hoping to hear.  It all made sense and conformed to what I have experienced until the compression part.
However, I do not discount a theory simply because a simulator produces something different.  If the person(s) writing the code for the simulator did not subscribe to a particular theory, it is doubtful that the simulator would produce results confirming it.

Ken

I didn't watch the whole thing.  I saw the first five or so minutes, which gave ten seconds worth of information over and over without a video that could have proven his point.  Then I skipped around and saw some utter balderdash. 

Thank you.  If you and Igor agree then balderdash it is, or maybe it was hogwash?  Not sure.  I will delete the link less some other unsuspecting seeker of truth stumbles onto it.

I did a lot of computer modeling when I had more hair but it was in the field of economics and scheduling.  If you feed a bunch of data into a model written by a Keynesian then feed the same data into a Friedman model or game theory model you would get totally different results.  That is what prompted me to comment that excluding one from the model also excludes it from the results.  I know that science and economics are quite different, but I can say, coming from Friedman side, that Keynesian is balderdash AND hogwash.   

Thank you.  If you and Igor agree then balderdash it is, or maybe it was hogwash?  Not sure.  I will delete the link less some other unsuspecting seeker of truth stumbles onto it.

I did a lot of computer modeling when I had more hair but it was in the field of economics and scheduling.  If you feed a bunch of data into a model written by a Keynesian then feed the same data into a Friedman model or game theory model you would get totally different results.  That is what prompted me to comment that excluding one from the model also excludes it from the results.  I know that science and economics are quite different, but I can say, coming from Friedman side, that Keynesian is balderdash AND hogwash.   

There are much worse explanations than that. The basic problem is that he tries to explain it to details without really understanding it. I can imagine he wanted explain "why" and he got himself to troubles. If you say lift comes from change of mass momentumm what is coupled with force making air pressure difference and then you want to explain why deflection apears and you come to situation that you see that it the pressure difference causing it, you are running in circles  ... and if you want break that circle, you must google something like london dispersion force which has ability to change boiling temperature of gases, but certainly not deflection of the air stream   

You do not know anything until you use your theory for figuring up numbers fitting reality. So you can try that simulator (google Martin Hepperle) and you can model some NACA arifoil and compare with real available measured data. Some years ago I tested my airfoil on that simulator. Then I did my own calculation of my own model to measure tighters possible corner with maximally deflected controll surfaces and I got data which I was able to compare with measured radius. I posted it in old stuka forum. If that worked (aproximately of course, difference was smaller that 20%) then also that simulator and also my calculation worked properly. So if his explanation shows thing completaly opposite than results of that simulator, even withour real numbers, it will be probably wrong.

BTW that "compression" stuff in the video is based on "zone lift" theory, which does not match measured data of pressure distribution at all.
That "compression front of LE" really appears, but only in case of no or very low AoA, when airfoil does not make lift too much, while completaly disapear at high AoA when airfoil makes lot of lift, what is in contradiction with that theory. (measured)
It is also in contradiction with airfoil moment which is opposite than it should be if the zone lift theory would be proper.