Observe a heavily loaded, fully fueled, high-time Cessna 402 waddle out for yet another cargo flight, and you'll understand the meaning of relative motion. Ten thousand-hour wing structures sag under the load, bouncing lazily with every seam in the tarmac. Under such strain, the lower wing panels buckle between primary structural members, causing the skins to wrinkle and "oil can." It can be scary if you don't understand that airplanes are designed to flex. If they did not, critical structures would crack from fatigue—quickly and without warning.
展开▼
