#Takeoff_Illusion A jet plane taking off from an aircraft carrier is propelled by its powerful engines while being thrown forward by a catapult mechanism installed in the carrier deck.The resulting high acceleration allows the plane to reach takeoff speed in a short distance on the deck.However, that high acceleration also compels the pilot to angle the plane sharply nose-down as it leaves the deck.Pilots are trained to ignore this compulsion, but occasionally a plane in flown straight into the ocean. Physics behind the compulsion- Our sense of vertical depends on visual clues and on the vestibular system located in our inner ear.That system contains tiny hair cells in a fluid. When we hold our head upright, the hairs are vertically in line with gravitational force F(g) on us and the system signals our brain that our head is upright. When we tilt our head head backward by some angle, the hairs are bent and the system signals our brain about the tilt. The hairs are also bent when we are accelerated forward by an applied horizontal force F(app).The signal sent to our brain then indicates, erroneously, that our head is tilted back,to be in line with an extension through the vector sum F(sum)=F(g)+F(app). However, the erroneous signal is ignored when visual clues clearly indicate no tilt,such as when we are accelerated in a car. A pilot being hurled along the deck of an aircraft carrier at night has almost no visual clues. The illusion of tilt is strong and very convincing, with the result that the pilot feels as though the plane leaves the deck headed sharply upward. Without proper training, a pilot will attempt to level the plane by bringing its nose sharply down, sending the plane into the ocean!!
Posted on: Wed, 27 Aug 2014 03:29:42 +0000