Originally Posted by Q94H
Does compressibility drag have a higher effect on the heavier aircraft than the lighter aircraft
Compressibility effects are a function of Mach number. At a given altitude the heavier aircraft will have its max L/D at a higher Mach number than the lighter aircraft. So the question really is: does max L/D reduce with Mach number? While the answer will probably depend on aircraft type, the following graph shows the variation of maximum L/D with Mach for one widebody twin transport airplane type.
P.S.
Based on the above graph, when a heavier and a lighter aircraft descend side-by-side each at its max L/D from the same cruise altitude, the lighter aircraft will have a slight advantage until they get to lower altitudes where the heavier aircraft has the advantage.