This discussion centers on the molecular interactions between nitrogen molecules and airplane wings, specifically regarding lift generation. Participants clarify that molecular attraction, such as van der Waals forces, plays a negligible role in lift compared to the physical action of the wing pushing air down, as described by Newton's third law. The Coanda effect is mentioned as an aerodynamic phenomenon, but it is emphasized that molecular interactions are not critical to understanding lift. The conversation also touches on the relevance of molecular structure to macroscopic flight principles.
PREREQUISITESAerospace engineers, physics students, and anyone interested in the scientific principles of flight and aerodynamics.
nbo10 said:There a few threads around here about how airplanes fly. I would suggest you read a few of them and then repostulate your initial assumptions on what creates lift. Why do you assume that they atmosphere and the wing has to stay together?
im guessing nitrogen does most of the lift since it's the most abundent in air. how does a nitrogen molecule stick to a steel molecule (plane's)? is there a short term electronic bond between the two molecules?
if they wouldn't stick (which they do) there would be no interaction at all.
that's how energy is trasnfered between the air and the wing. no molecule knows of each other
Ratch said:scumhearted,
An airplane does not require molecular attraction of its wing with a gas to fly. Compared with the forces required lift the airplane, molecular attractions are insignificant.
There doesn't have to be any attraction. An airplane's wing physically pushes air down so that according to Newton's third law of mass, the reaction force pushes the plane up in the opposite direction. Where did you get the idea of a "stickyness" or attraction of the air to the wing?
Energy is transferred between the fuel and the engine and the airframe. Any energy used to push the air around is wasted as far as transporting the airplane is concerned.
Ratch
P.S. In English, first words of sentences are capitalized. That makes sentences much easier to read.
Ratch said:scumhearted,
An airplane does not require molecular attraction of its wing with a gas to fly. Compared with the forces required lift the airplane, molecular attractions are insignificant.
There doesn't have to be any attraction. An airplane's wing physically pushes air down so that according to Newton's third law of mass, the reaction force pushes the plane up in the opposite direction. Where did you get the idea of a "stickyness" or attraction of the air to the wing?
Energy is transferred between the fuel and the engine and the airframe. Any energy used to push the air around is wasted as far as transporting the airplane is concerned.
Ratch
P.S. In English, first words of sentences are capitalized. That makes sentences much easier to read.
Ratch said:scumhearted,
An airplane does not require molecular attraction of its wing with a gas to fly. Compared with the forces required lift the airplane, molecular attractions are insignificant.
There doesn't have to be any attraction. An airplane's wing physically pushes air down so that according to Newton's third law of mass, the reaction force pushes the plane up in the opposite direction. Where did you get the idea of a "stickyness" or attraction of the air to the wing?
Energy is transferred between the fuel and the engine and the airframe. Any energy used to push the air around is wasted as far as transporting the airplane is concerned.
Ratch
P.S. In English, first words of sentences are capitalized. That makes sentences much easier to read.
scumhearted said:also, you can't deny the molecular structure of things. just because we live day to day on a macroscopic world, and base our lives on it, you can't deny the fundamentals of everything
ZapperZ said:Er... this is empty talk.
No one is denying anything here. The question here is whether it is RELEVANT or not to the phenomenon! I'm sure when you do your many calculations, you ignore the gravitational field from Alpha Centauri, don't you? Do you think leaving out such a thing affects the accuracy of many of the things you do or calculate?
Do not go into this line of discussion until you have done a considerable reading on "emergent phenomena".
Zz.
scumhearted said:yes it is relevant. it's related to the boundary layer and that is related to the stall limit. and that is related to the plane crashing
One way of looking at this is "void abhorence" effect. As air flows around a convex surface, what would otherwise be a void near the surface is filled in by the air (else a near zero pressure void would be formed). If the flow is laminar or only mildly turbulent, the air flow tends to follow the curved surface. In a heavily stalled state, what would be a "void" could be filled with one very large vortice.scumhearted said:I was referring to the coanda effect.