why does air drag decrease above mach1.2?

Question

during transonic flight the drag is b coz air molecules are not able to move away as fast as the plane if thats the case drag should continue even above mach1.2

Answer 1

Read this: http://aerodyn.org/Drag/speed-drag.html

Answer 2

The coefficient of drag falls, not the drag, Cd is a multiplier applied top the theoretical plate drag of an object with the same cross sectional area as the object in question. So a car may have a Cd of 0.29 because it gets 29% of the drag that a flat plate of that size would.

aerodynamic drag = 1/2 D x A x V^2

where D is the density of air and A is the area. But the drag on a real body is multiplied by a factor which varies from 1.05 for a cube to 0.04 for a streamlined body.

drag = 1/2 D x A x V^2 x Cd

So at low supersonic speeds the Cd peaks, then falls off, but that fall is much slower than the square law rise with velocity.

Answer 3

Slightly after mach the aircraft is enveloped in a vortex.You can actually see it when you watch a jet approach and pass mach.