B767Driver
New Member
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The air approaching a subsonic wing in basically incompressible...the air has no advance warning that the wing is approaching...and the air is able to maintain a laminar flow over the wing. A wing near sonic speeds now is able to begin compressing the air ahead of its path...giving the air "advance" warning that it is approaching.
[/ QUOTE ] The air is actually able to start moving out of the way when a subsonic aircraft is approaching. Due to air's incompressible nature at low speeds, a pressure wave travels slightly ahead of the aircraft. Think of this as the 'bow wave' of a boat.
When an aircraft is supersonic, then the aircraft 'sneaks up' on the air molecules it encounters and has to force its way through. (Remember, pressure waves are transmitted through air as sound waves. If you are faster than the speed of sound, no pressure wave can stay ahead of you.)
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Oops...that's what I meant to say! (regarding advance warning/comp/incomp). However...I did mean the part of sweep introducing the spanwise flow to reduce local velocities impacting the leading edge. I guess we'll see what Seagull has to say about this.
[ QUOTE ]
The air approaching a subsonic wing in basically incompressible...the air has no advance warning that the wing is approaching...and the air is able to maintain a laminar flow over the wing. A wing near sonic speeds now is able to begin compressing the air ahead of its path...giving the air "advance" warning that it is approaching.
[/ QUOTE ] The air is actually able to start moving out of the way when a subsonic aircraft is approaching. Due to air's incompressible nature at low speeds, a pressure wave travels slightly ahead of the aircraft. Think of this as the 'bow wave' of a boat.
When an aircraft is supersonic, then the aircraft 'sneaks up' on the air molecules it encounters and has to force its way through. (Remember, pressure waves are transmitted through air as sound waves. If you are faster than the speed of sound, no pressure wave can stay ahead of you.)
[/ QUOTE ]
Oops...that's what I meant to say! (regarding advance warning/comp/incomp). However...I did mean the part of sweep introducing the spanwise flow to reduce local velocities impacting the leading edge. I guess we'll see what Seagull has to say about this.