4 ms·

This looks incredible as usual. What puzzles me, though, is why some people find flying puzzling. At least the kind that we do, ie. helicopters and fixed-wing a

This looks incredible as usual. What puzzles me, though, is why some people find flying puzzling. At least the kind that we do, ie. helicopters and fixed-wing aircraft. It's easy to accept a fan works: just put your hand there and feel the draft. A wing is just like a linear fan pushing air down. It's completely intuitive to understand for me. The difficulties are just in making it practical and controllable. Conversely, many people don't seem concerned at all with bird or insect flight, which I find a lot harder to understand.

pants2 3y ago
Because an airplane doesn't move its wings like a bug or helicopter, and it's wings aren't shaped like fan blades. One might look at a plane and conclude that since the wings and engines are parallel to the ground, it must only move laterally.
- globular-toast 3y ago
  Of course it moves its wings. That's what the runway is for.
- jahewson 3y ago
  Rectilinear fan blades are shaped very similarly to aircraft wings. And it does only move laterally until the ailerons are moved away from being parallel with the ground.
d--b 3y ago
I guess this is somewhat counter intuitive: https://www.youtube.com/watch?v=NBsvzMi9-f8 https://www.youtube.com/watch?v=NBsvzMi9-f8 So yeah, fans are puzzling too.
- stavros 3y ago
  That seems like the Coanda effect more than anything.
- convivialdingo 3y ago
  If you watch it very slowly, the paper initially folds under the mouth and then it blows out straight. I'm guessing the initial puff creates a high pressure area on top of the paper, rolling it downward and back. Them after the puff has pushed the air away, there is now a low pressure zone on top of the paper which lifts it up as the air below is rushing upwards around the sides of the paper.
andrewla 3y ago
I think many of us were taught in school that airfoil shape was somehow magical -- that the fact that it was bowed more on the top was responsible for the fact that it worked. This is only partially true, though; a totally flat wing can also support flight. The shaped nature of the wing contributes to its efficiency (and other factors) but do not make other wing shapes incapable of supporting flight. The reality is that the Wright brothers' innovation was not the airfoil shape or even the lightweight motor. It was the control surfaces, to allow the operator to adjust the plane's attitude on the three axes of rotation, allowing actively stabilized flight. Paper airplanes and kites demonstrate all the same principles of heavier-than-air flight (the Wright brothers even had a kite version of their airframe they used for testing), despite the fact that they generally do not exhibit shaped airfoils.
- amenhotep 3y ago
  The Wrights did use a rudder and "horizontal rudder" on the 1903 Flyer, but they were for some time determined to achieve roll control by warping the wings rather than using control surfaces, and were only forced to adopt ailerons as other pioneers began demonstrating how superior a paradigm that was. So they don't deserve too much credit on that score!
  - andrewla 3y ago
    "Control surfaces" was more specific than I intended; what I meant was that their plane allowed them to control all three axes of rotation, and that was the innovation - that they could control pitch, yaw, and roll independently and that allowed them to have active stable flight. Without those controls, flight is basically impossible, and with them, you could use nearly any airfoil shape (modulo engine power, drag, and stall speed considerations) and achieve heavier-than-air flight.
  - BWStearns 3y ago
    Ailerons were really only invented when they were (and named in French) because the Wrights were extremely litigious, they sued Curtiss for using ailerons and basically destroyed American aviation for a decade allowing the French a temporary lead. This had an interesting cultural effect of lots of things becoming named in French across aviation (including things like the weather code for mist being "br" for brume to this day).
tekla 3y ago
This is an incredible (over)simplification of flying. We still don't have a very good understanding of turbulence. Navier Stokes equations still make Aerospace engineers drink. Yes its stupid simple if you care about the simplest of analogies, but if you try to understand it, there are reasons why 80% of people drop out.
- jebarker 3y ago
  I think you mean incredible oversimplification
NovemberWhiskey 3y ago
Surely it's a less impressive result that something powered by mains electricity can move the air in a draft than that a multi-hundred-ton aircraft can fly over the highest mountains. It's the size of the aerodynamic forces and the complexity of the physical mechanisms that create them that many people have trouble with. In particular: intuitions can be pretty wrong, most simplified explanations are wrong under simple experiments, and the problems exhibit scale variance that is unfamiliar (e.g. Reynolds number). One time I was working on air data computer for a transonic aircraft that could fly up to about M0.95 - during flight test, an air data probe mounted on a nose boom was used to supply impact and static pressures, angle of attack and sideslip etc. for various air data calculations like airspeed and altitude. I was fascinated that there was a term in the calculation that related to the aircraft flap position - what's happening way out on the trailing edge of the wing actually has a meaningful effect of pressures measured on a boom out the front of the nose during certain regimes of flight.
- globular-toast 3y ago
  It's just a matter of scale. What's impressive to me with the big aircraft is that we can organise thousands(?) of people to build something that big. But when it comes to the principle of flying it's just a bigger version of the fan. If you were to say they used the same amount of energy as a fan then that would be impressive. But they don't, they burn tons of fossil fuels. Geese can fly over the highest mountains too and all they eat is grass.
  - NovemberWhiskey 3y ago
    >it's just a bigger version of the fan I mean, actually, it isn't - that's the whole point about scale variance and Reynolds number and why wings that work for insects are not the wings that work for jumbo jets.
risenshinetech 3y ago
Who are these mysterious people you're interacting with who are concerned with (but don't understand) the physics of flight, but who are also not concerned with bird or insect flight?

pants2 3y ago

Because an airplane doesn't move its wings like a bug or helicopter, and it's wings aren't shaped like fan blades. One might look at a plane and conclude that since the wings and engines are parallel to the ground, it must only move laterally.

globular-toast 3y ago
Of course it moves its wings. That's what the runway is for.
jahewson 3y ago
Rectilinear fan blades are shaped very similarly to aircraft wings. And it does only move laterally until the ailerons are moved away from being parallel with the ground.

d--b 3y ago

I guess this is somewhat counter intuitive: https://www.youtube.com/watch?v=NBsvzMi9-f8 https://www.youtube.com/watch?v=NBsvzMi9-f8 So yeah, fans are puzzling too.

stavros 3y ago
That seems like the Coanda effect more than anything.
convivialdingo 3y ago
If you watch it very slowly, the paper initially folds under the mouth and then it blows out straight. I'm guessing the initial puff creates a high pressure area on top of the paper, rolling it downward and back. Them after the puff has pushed the air away, there is now a low pressure zone on top of the paper which lifts it up as the air below is rushing upwards around the sides of the paper.

andrewla 3y ago

I think many of us were taught in school that airfoil shape was somehow magical -- that the fact that it was bowed more on the top was responsible for the fact that it worked. This is only partially true, though; a totally flat wing can also support flight. The shaped nature of the wing contributes to its efficiency (and other factors) but do not make other wing shapes incapable of supporting flight. The reality is that the Wright brothers' innovation was not the airfoil shape or even the lightweight motor. It was the control surfaces, to allow the operator to adjust the plane's attitude on the three axes of rotation, allowing actively stabilized flight. Paper airplanes and kites demonstrate all the same principles of heavier-than-air flight (the Wright brothers even had a kite version of their airframe they used for testing), despite the fact that they generally do not exhibit shaped airfoils.

amenhotep 3y ago
The Wrights did use a rudder and "horizontal rudder" on the 1903 Flyer, but they were for some time determined to achieve roll control by warping the wings rather than using control surfaces, and were only forced to adopt ailerons as other pioneers began demonstrating how superior a paradigm that was. So they don't deserve too much credit on that score!
- andrewla 3y ago
  "Control surfaces" was more specific than I intended; what I meant was that their plane allowed them to control all three axes of rotation, and that was the innovation - that they could control pitch, yaw, and roll independently and that allowed them to have active stable flight. Without those controls, flight is basically impossible, and with them, you could use nearly any airfoil shape (modulo engine power, drag, and stall speed considerations) and achieve heavier-than-air flight.
- BWStearns 3y ago
  Ailerons were really only invented when they were (and named in French) because the Wrights were extremely litigious, they sued Curtiss for using ailerons and basically destroyed American aviation for a decade allowing the French a temporary lead. This had an interesting cultural effect of lots of things becoming named in French across aviation (including things like the weather code for mist being "br" for brume to this day).

tekla 3y ago

This is an incredible (over)simplification of flying. We still don't have a very good understanding of turbulence. Navier Stokes equations still make Aerospace engineers drink. Yes its stupid simple if you care about the simplest of analogies, but if you try to understand it, there are reasons why 80% of people drop out.

jebarker 3y ago
I think you mean incredible oversimplification

NovemberWhiskey 3y ago

Surely it's a less impressive result that something powered by mains electricity can move the air in a draft than that a multi-hundred-ton aircraft can fly over the highest mountains. It's the size of the aerodynamic forces and the complexity of the physical mechanisms that create them that many people have trouble with. In particular: intuitions can be pretty wrong, most simplified explanations are wrong under simple experiments, and the problems exhibit scale variance that is unfamiliar (e.g. Reynolds number). One time I was working on air data computer for a transonic aircraft that could fly up to about M0.95 - during flight test, an air data probe mounted on a nose boom was used to supply impact and static pressures, angle of attack and sideslip etc. for various air data calculations like airspeed and altitude. I was fascinated that there was a term in the calculation that related to the aircraft flap position - what's happening way out on the trailing edge of the wing actually has a meaningful effect of pressures measured on a boom out the front of the nose during certain regimes of flight.

globular-toast 3y ago
It's just a matter of scale. What's impressive to me with the big aircraft is that we can organise thousands(?) of people to build something that big. But when it comes to the principle of flying it's just a bigger version of the fan. If you were to say they used the same amount of energy as a fan then that would be impressive. But they don't, they burn tons of fossil fuels. Geese can fly over the highest mountains too and all they eat is grass.
- NovemberWhiskey 3y ago
  >it's just a bigger version of the fan I mean, actually, it isn't - that's the whole point about scale variance and Reynolds number and why wings that work for insects are not the wings that work for jumbo jets.

risenshinetech 3y ago

Who are these mysterious people you're interacting with who are concerned with (but don't understand) the physics of flight, but who are also not concerned with bird or insect flight?