At transonic speeds (near the velocity of audio), it can help to comb the wing backwards or forwards to scale back drag from supersonic shock waves as they start to form. The swept wing is simply a straight wing swept backwards or forwards. چرخ‌های محرک یک لوکوموتیو. چرخ قطار یا https://august8uu01.gynoblog.com/26779010/the-basic-principles-of-قطار