This got me a little confused at first because I was thinking that a heavier aircraft at the same IAS would require a greater value of Cl ie greater angle of attack, more drag. But I guess if normal descent speeds are above best L/D speed, then this would make sense as the drag curve shifts to the right with increasing weight. Does this mean that if the normal speed for descent was the best L/D speed, that a heavier aircraft would glide less distance for the same IAS?