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So you are correct in the fact that the statement that "the air must flow on top faster to meet the bottom" is not correct. It's an invalid statement that is used to simplify aerodynamics. A way to think of this is that when the wing hits the air, the air must be moved. That air is deflected, and so the pressure will decrease as less air is in that "area". Bernoulli's principle states that when the pressure of a fluid drops, air speed must increase. It's a property of fluids. So, the air will speed up. The pressure will drop on both the upper and the lower surface. However, the geometry of the airfoil is what makes these different. The pressure drops more on the top of the airfoil due to the geometry, and less on the bottom. So, the air speeds up on both surfaces of the airfoil, but the top moves faster.

@@AerodynamicAnimations Air hits the wing leading edge ... it seems it would be compressed (pressure increase, not decrease) ... maybe only at the leading edge

@@adastra8653 So yes, the air will stop at a certain point (called the stagnation point) at the front of an airfoil. If you see an air distribution, the highest pressure is at the very front of the airfoil because air stops. But, along the top and bottom surface, it does not stop.

@@smartalpha thank you, appreciate the comments. I am working on having better explanations as my videos do leave lots of information out.

i'm way too tired to give a good answer but i don't know if you searched or not so im gonna give you the answer from google that is from reddit adding winglets also modifies the spanwise lift distribution, putting more lift (and thus bending moment) outboard. This requires more wing structure and thus weight. For a fighter, where maneuverability is paramount and efficiency is not, this is not a good tradeoff.

There's lots of reasons. For one, winglets are used to reduce induced drag, which leads to more efficient planes. Airlines care about this for things like fuel efficiency, which in turn saves money. Gliders want aerodynamic efficiency to stay in the air longer. Furthermore, winglets affect induced drag. Induced drag is not the prevailing drag at high speed. Things like wave drag will take over as the dominant form of drag as fighter jets reach top speed. The winglet would lead to more shocks, thus more drag at transonic/supersonic speeds. There's a design tradeoff, and fighter jets want maneuverability and speed, which winglets don't do.

No, it’s not important. It’s a consequence of deploying flaps. Drag is proportional to velocity^2, so at slow speeds (takeoff and landing) it isn’t that big of an issue compared to faster speeds like cruise. More drag is produced as a consequence of induced drag being proportional to lift. There’s another video on my channel about that. But that drag is why flaps are not deployed during flight. We do not need as much lift from the wings, and we want to minimize drag so we retract flaps.

​@@AerodynamicAnimations You still haven't corrected your statement. You don't understand drag.

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Good point! It does help. I'll address this in a later video.

Pilots claim that swept wings are hard to fly. Trainers have straight wing.

@@ArneChristianRosenfeldt We are talking about modest sweep angles. Angles like those of WWII aircraft for instance. You only need a few degrees for the outboard wing to produce more drag. Plenty of trainer aircraft do have a mild sweep angle.

@@leoa4c the lower the wing, the more dihedral. At some height even anhedral is used. No subsonic plane sweeps their wings. Flying wings do it because their tips act as tail. It actually worsens stability. Twin boom is the real solution to pusher props. But then again for aerobatic I like that in a flying wing the tail never passes through the wake of the wing. The wing tips of the Concorde are actually for stabilisation, not lift .

This animation is in blender, but other videos may include other software meant for more aerodynamic visuals like Ansys

The wings do not have the same angle of attack with dihedral when disturbed. When the aircraft rolls, it will also slip in that direction. This side slip results in the wings seeing different wind vectors, and therefore different angles of attacks. In a straight wing, they’d see the same wind vector. It’s easier to see this if you consider angle of attack as the change in vertical velocity over the wind vector velocity. It clearly shows the higher wing would result in a decrease in angle of attack and the lower in a higher angle of attack. The angle of attack difference results in the low wing producing more lift, and the high wing less lift. This is what causes the roll moment to return to wings level.

Can we start from a hang glider? Straight wing with tail. Heavy pilot in a nacelle front / below. Now you apply your normal forces.

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I’ve never actually heard of that before, but I wouldn’t mind making a second video on other types of stability like saddle points and meta stability if you’re interested!

It's only a little worse for wear after falling into the abyss and getting chewed by the dog.

Thanks Louis, glad it helped!

Thank you!