Originally Posted by
chornedsnorkack
Just what is wrong about having airflow separate? Especially at high Mach?
Look at it this way: the lower surface of the wing intercepts airflow, which is forced to accelerate around the wing. The wing creates lift at all angles of attack except approximately 0 degrees, approximately 90 degrees, approximately 180 degrees and approximately 270 degrees.
At approximately 0 degrees, there is no lift because there is exactly as much air accelerated above wing as below wing. At 90 degrees, the same applies.
Now, from 0 to certain stalling angle of attack, the larger the angle of attack, the larger the lift. This should provide the necessary vertical and therefore lateral stability.
So what if the speed of airflow exceeds the speed of sound over the wing, or under the wing, or in free airflow? Yes, shockwaves are generated, and the airflow separates easily over the wing - but the airflow under the wing has nowhere to separate and has to support the wing for simple Newton second law reasons, whether its speed is 0,8 M, 1,8 M or 18 M...
Not sure what kind of wing you are thinking of. Lift is created at 0 degrees AOA by the action of air passing over the top surface at a higher speed than under it. This causes a lower pressure area to form above the wing thus sucking the a/c into the air. If you increase the AOA until the air separates the lift is lost so it is only the engines thrust pushing up that will act against the weight. If thrust is insufficent then you will descend. (Possibly backwards as happened to a Trident many years ago.)
At close to Mach1 the air over the top of the wing will be supersonic and so will form a shockwave. As the air hits the shockwave it is squashed and so creates a high pressure area. (The reverse of what you want on top of the wing.) Newton's laws have very little to do with lift compared to Berniolie (Sorry having spelling breakdown.) and his gas flow laws. It is also one of the reasons for "control reversal" when the pioneers were trying to break the sound barrier.
Feel like I am teaching most of you to suck eggs but perhaps I have misunderstood chornedsnorkack's post.