71–80 of 178 posts
Doesn't the leading edge being thick and rounded up top deflect away air from getting to the slant-plane right behind it creating a low pressure zone above the wing?
Same will apply in flat-wing cases because angle of attack will cause same effect.
What am I missing?
I'm surprised people don't start with the basics on this confusing topic. The third law of Newton's mechanics tells us that for the plane to get an up force to counteract the gravity, the air must receive and equal amount of down force. Therefore what planes must be doing is deflect air masses down. A plane must be applying a downward force to air masses, with total force value of "mass * g", i.e. supply "mass * g *…
I'm tired of this headline, its an oversimplification. We absolutely DO understand how and why they stay in the air, we just don't have the hard numbers behind it.
> We absolutely DO understand how and why they stay in the air, we just don't have the hard numbers behind it. The article claims the opposite: we do have the hard numbers behind it (we can predict how a wing behaves), but we don't have a good conceptual explanation for it at a layman's level (the how and why, if you so will).
They are very complicated and the complexity is required to understand all the weird edge cases
Earlier quoted context omitted.
> can also sail faster than the wind at times. Really? Can you elaborate?
Imagine a sailboat pointed 90° relative to the wind so that the wind is coming right at its side. The sail is curved so that it takes that wind and redirects it towards the rear of the boat, giving it forward thrust. The boat starts moving forward. But, because the wind is perpendicular to the boat, even when its moving the wind is still coming in at the same velocity, so it's still producing thrust. If you can get t…
I'm surprised people don't start with the basics on this confusing topic. The third law of Newton's mechanics tells us that for the plane to get an up force to counteract the gravity, the air must receive and equal amount of down force. Therefore what planes must be doing is deflect air masses down. A plane must be applying a downward force to air masses, with total force value of "mass * g", i.e. supply "mass * g *…
You really can't "just" explain lift simply.
The key ingredients that I took away from the above are that circulation and the Kutta condition are fundamental to explaining lift.
I think people's confusion with this situation is that there's no simple cause and effect. It's just that the fluid equations have a solution that has circulation and that gives lift, but you can't solve for it like you can with most mechanics problems, because you need a global solution that satisfies the fluid equations.
The fact that I do not understand the equations doesn't mean there is anything mysterious behind it.
There might be some artistry with regards to actually designing the aerodynamic shapes. We have no way of finding the best possible shape yet, this is largely a process of trial and error (though nowadays it can be automated with simulation without actually having to go through building physical model).
Earlier quoted context omitted.
Yeah. There are two kinds of sailboats. There's the big square sailed ones which always have to move downwind. Then there are the triangular sailed ones, which can move in any direction except for right into the wind. (Maybe a 30 degree on each side dead zone). The square sailed boats can't move faster than the wind, as they just rely on the air pushing on the sail to move with the wind. That's also how the triangula…
> There's the big square sailed ones which always have to move downwind. Actually, that's not true. Square rigged "pirate-style" ships are more efficient when sailing downwind compared to fore-and-aft style sailboats, but they can still sail just fine close-hauled (into the wind) or on a reach (perpendicular). There are some efficiency pros and cons to both styles, but they all have the same aerodynamic capabilities.…
True, but it gets more complicated than that. For fast long-distance commercial travel they were replaced by the steam and later diesel propulsion, which both a) were faster and b) required less crew (so were logistically superior).
On the other hand, where sailing is still used (and that's mainly sport and leisure) the square rig is still here, only in an evolved form: the spinnaker. But whenever the speed is not the primary factor, fore-and-aft rigs (primarily Bermuda) is preferred because it requires far less crew. And then again, when the goal is to have plenty of crew -- like in some navy office training -- classical square rig is still highly merited [1].
I don't think there is anything mysterious about lift. We can model it very well, we have precise equations that predict the exact results (though we can't solve them) and we know where these equations come from. The fact that I do not understand the equations doesn't mean there is anything mysterious behind it. There might be some artistry with regards to actually designing the aerodynamic shapes. We have no way of…
Mysterious doesn’t mean magical, it just means there’s an unexplained gap in what we understand, which is the case.
I'm surprised people don't start with the basics on this confusing topic. The third law of Newton's mechanics tells us that for the plane to get an up force to counteract the gravity, the air must receive and equal amount of down force. Therefore what planes must be doing is deflect air masses down. A plane must be applying a downward force to air masses, with total force value of "mass * g", i.e. supply "mass * g *…
The obvious follow-up question is : why does a wing deflect the air down?