Airliners don't have the wings going straight out, instead being swept back. You can also sweep them forward to get the same effect, but you will rarely want to do that due to other problems. This means that the cross sectional area of the aircraft varies less along the length and reduces wave drag.
If there's no lift there's no pressure different between the upper side of the wing and the lower side of the wing. But if there's lift there's higher pressure on the bottom and lower on top, so air wants to flow around the wing, from bottom to top, producing a wingtip vortex. This flow creates drag, and this drag is called lift-induced drag or just 'induced drag'.
The area rule is about minimizing wave drag by keeping the cross sectional area of different parts of the aircraft close to the cross sectional area of the corresponding cross-section of a minimal drag body. It leads to wing sweep and certain fuselage shapes.
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Airliners don't have the wings going straight out, instead being swept back. You can also sweep them forward to get the same effect, but you will rarely want to do that due to other problems. This means that the cross sectional area of the aircraft varies less along the length and reduces wave drag.
If there's no lift there's no pressure different between the upper side of the wing and the lower side of the wing. But if there's lift there's higher pressure on the bottom and lower on top, so air wants to flow around the wing, from bottom to top, producing a wingtip vortex. This flow creates drag, and this drag is called lift-induced drag or just 'induced drag'.
The area rule is about minimizing wave drag by keeping the cross sectional area of different parts of the aircraft close to the cross sectional area of the corresponding cross-section of a minimal drag body. It leads to wing sweep and certain fuselage shapes.