wow, shiver me timbers
i am glad to have brought this up again cuz' i know zilch.
yes, it was hashed some time back and KE=1/2 mv(squared) was used to illustrate this.
it was proven (altough with much debate) that a lighter a/c would have a higher ROD than a heavier a/c.
sorry i have not put in my response, blasted thing went dead on me.
yes, it is about rate of descent, two perfectly fine aeroplanes descending at the same speed. with thrust at idle.