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Originally posted by TheDollyLlama
wow. now that's a reply. maybe you can answer this one for me.
You're saying that this thing would yaw by vectoring the thrust, right?
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Not quite, although apparently it's capable of that to some extent, too. But by deploying the control surfaces differentially (and especially note that they're not coplanar) the resultant forces can go in all kinds of different directions. It's vaguely analogous to turning a tracked vehicle like a tank or a bulldozer by moving the tracks at different rates. The key to the trick is that a computer is constantly translating the pilot's command inputs into movements of the control surfaces by calculating what forces will be devloped and how the forces will affect the aircraft's position and momentum (or "state vector"). No mechanical control linkage could ever do that.
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how is that different than the angle of attack maneuvers the f22 is capable of?
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Actually, getting to high-alpha (angle of attack) isn't all that difficult; every student pilot is taught how to stall the airplane...with emphasis on how not to except when landing. What makes flight on that edge tricky is maneuvering at all once you get there.
As alpha exceeds a critical value that's a function of airspeed, the laminar flow across the wings and control surfaces separates and becomes turbulent, lift is lost, and the surfaces "stall". A stalled control surface or wing doesnt exert any significant useful force on the aircraft, so whatever manuverability you have at that point is going to have to come from somewhere else--namely a reaction force like vectored thrust. That's how a Harrier takes off and manuevers in hover, and how the Shuttle is turned while it's on-orbit.
A hovering Harrier could be said to be in a high-alpha flight regime because its effective airspeed is near zero, so critical alpha is vanishingly small; the aircraft is competely stalled but is still manuverable because of vectored thrust. It's no longer a genuinely aerodynamic creature; it's basically ballistic.