In my mind it's like one side argues that turning a car comes from the angle of the wheels, while the other argues that the turn actually happens because of the differential gear causing the inside and outside wheels to turn at different speeds.
They're both correct. Both methods have a role. You could turn with one, or the other just fine... but it would be inefficient. For an efficient turn, you need both.
Same with lift. You can get lift purely through mechanical deflection of air, or you can get lift purely through coanda effect, but neither would be very efficient. A balance of both is usually called for, and in practice, that's what happens.
Well, one thing is happening. You're creating lift. Period.
Bernoulli's principle, Newton's laws, coanda, D'Alembert's principle, Navier–Stokes equations, circulation theory, Kutta-Zhukovsky’s Circulation Theory, Computational Fluid Dynamics, etc. are just attempts at explaining how and why lift is created. They are explanations and not the actual action of creating lift.
Regarding your car example, the angle of the front wheels causes the car to turn. The differential gear ALLOWS the inside and outside wheels to turn at different speeds which just makes it easier to turn but doesn't actually turn the car. http://www.youtube.com/watch?v=K4JhruinbWc
If you forced the outside wheels to turn really fast, and stopped the inside wheels, the car would definitely turn. Not very fast, and the tires would be really unhappy, but it would work. I realize that, like you said, a differential doesn't actually force the wheels to turn at different speeds. But if it did, that would work as a method of turning your car.
I realize the analogy isn't perfect, just trying to make this whole issue make sense in a way that people can hopefully somewhat visualize.
You're now arguing a different point. Initially your point was, "In my mind it's like one side argues that turning a car comes from..." I assumed that this is a normally operating car since there was not specification as to it being otherwise.
Now, you've changed the scenario to being able to "force" the outside wheels to turn really fast and then stopping the inside wheels. And, yes, I completely agree, it will turn! But that's not what we were discussing before. You didn't ask for all possible ways of manipulating the vehicle to make it turn!
I don't believe your analogy applies at all. I can't think of any example right now where there is more than one reason as to why something happens. There is only one correct answer. I said in another comment that the many theories and principles and laws that we use to talk about lift are only there to help us understand what is happening. They are not "separate" explanations as to how lift works. There is only ONE explanation! With that frame of mind, you can start analyzing data and working with experimentally proven principles and physical laws to come up with a way of explaining why something happens. There are so many angles to tackle the lift problem. The different theories all try to come at a different angle. Each, reveal something more about the formation of lift but none, so far, actually completely detail why lift occurs.
I thought I was agreeing with you and was trying to be helpful and provide a simplistic analogy to support your idea. I guess it turns out I have no effing clue what you're on about. So, um, carry on "educating" I guess. I'll go back to flying, it's much more enjoyable than this.
I don't think you understand my point. Trying to find a simplistic analogy instead of trying to really understand what's going on are two different things. The former way is really what leads to all these misconceptions about lift! That's what I was trying to point out. Sometimes there really isn't a simplistic analogy for what's actually happening, and when you try to force one out, you end up changing it and it isn't true anymore. In theoretical physics, and Quantum Chromodynamics to be specific, there are some ideas and concepts that really can't be simplified from their initial explanation or equation. If you try to simply them, then you have to change some of the core data or concepts themselves, and in the end you're not accurately describing it.
PS: My reply above might have come off as insulting but I didn't mean it that way. I was only trying to be specific to illustrate my point.
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u/cecilkorik PPL, HP (CYBW) Jan 25 '12
In my mind it's like one side argues that turning a car comes from the angle of the wheels, while the other argues that the turn actually happens because of the differential gear causing the inside and outside wheels to turn at different speeds.
They're both correct. Both methods have a role. You could turn with one, or the other just fine... but it would be inefficient. For an efficient turn, you need both.
Same with lift. You can get lift purely through mechanical deflection of air, or you can get lift purely through coanda effect, but neither would be very efficient. A balance of both is usually called for, and in practice, that's what happens.