how aircraft works

[hskalsi]

how aircraft works

[bernardo]

It has to reach a speed at which the amount of air crashing into the underside of the wing is enough to provide lift to counteract the mass of the plane weighing downwards

[thekraut]

sorry, but thats utter nonsense. its not rocket science, you know, so mass of air does not change anything. its the different velocity of air above and below the wings, resulting in a pressure difference (according to bernoullis law or something) as the over all energy of the system "air" has to stay constant. and that pressure drop is lifting the aircraft. and thats why the wings have that peculiar shape

[bernardo]

Yes, that's part of it as well, but it doesn't account for all of it. If the different velocity (and hence different pressure) of air above and below the wings were the only factor involved, it would not be possible to fly aeroplanes upside down. Indeed, such a scenario would lead to an upside-down plane accelerating to the ground even faster than the acceleration due to gravity.

[Ewood27]

I see you're in leg-pulling mode, bernardo. In normal flight (right way up) the wings are angled up into the airflow by a few degrees. When you fly upside down the wings are again angled up, i.e. away from the ground, so that the "underside" of the wing now provides the negative pressure and generates lift. It's true that the positive pressure under a wing helps provide lift, but around 90% of the lift comes from the reduced pressure on the wing top surface.

[Drewhound]

There isn't any "negative" pressure though I can see what you are getting at Ewood27. The pressure above the wing is lower than that below so the air, wanting to equalise that pressure, forces the wing upwards.

[Ewood27]

You're right, Drewhound. It's not really negative pressure but reduced pressure. Sloppy writing. In diagrams it's usually shown as minus above the wing and plus below. Same difference though.

[Ewood27]

hskalsi, if you click here it will take you to a page which explains how aircraft work in much more detail. I hope you find your answers there.

[bernardo]

No, Ewood, actually I was not in leg-pulling mode (whatever that is). I was giving part of the answer, just as thekraut gave part of the answer.

[ianess]

keep going guys....you`re doing great...just let me go for a HEDEX.