DEMM Engineering & Manufacturing - - CONTENTS - JANE WAR­WICK

The word ‘bum­ble’ is cen­turies old and is thought to be a mix of the words ‘bun­gle’ and ‘stum­ble’. Mostly to­day we as­so­ciate the word with the bum­ble­bee, that ro­tund in­sect that, ac­cord­ing to pop­u­lar leg­end, shouldn’t re­ally be able to fly. The fluid dy­nam­ics be­hind bum­ble­bees’ flight are dif­fer­ent from those that al­low a plane to fly. An airplane’s wing forces air down, which in turn pushes the wing (and the plane it’s at­tached to) up­ward. For bugs, the wing sweep­ing is a bit like a par­tial spin of a some­what crappy he­li­copter pro­pel­ler, but the an­gle to the wing also cre­ates vor­tices in the air like small hur­ri­canes. The eyes of those mini-hur­ri­canes have lower pres­sure than the sur­round­ing air, so, keep­ing those ed­dies of air above its wings helps the bee stay aloft. Take your arm and put it out to your side, par­al­lel to the ground with your palm fac­ing down. Now sweep your arm for­ward. When you reach in front of you, pull your thumb up, so that you flip your arm over and your palm is up­wards. Now, with your palm up, sweep your arm back. When you reach be­hind you, flip your hand over again, palm down for the for­ward stroke. Re­peat. If you gave your hand a slight tilt (so that it’s not com­pletely par­al­lel to the ground) you’d be do­ing some­thing sim­i­lar to a bug flap and now, gen­tle reader, you are air­borne. Thank you Michael Dickinson - pro­fes­sor of bi­ol­ogy and in­sect flight ex­pert at the Univer­sity of Wash­ing­ton.

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