Originally Posted by BARKINGMAD
Energy (momentum) is the product of the mass times velocity
Energy is the sum of kinetic and potential energy:
½*m*V² + m*g*H
where m = mass, V = velocity, g = acceleration of gravity, and H = height.
So for two points 1 and 2 of equal energy, we get: H2 - H1 = ½*(V2² - V1²) / g
Why does Mr Boeing provide me with distance tables showing increasing track miles needed with increasing weight
The track miles are not proportional to weight, are they? I suspect that Mr Boeing's distance tables are based on a fixed speed schedule. At a fixed speed the L/D changes with weight, and therefore the glide angle changes with weight. If the descent speed is 300 kt, for example, that speed will be closer to the minimum drag speed at 60 tons than it is at 40 tons. Hence the L/D at 60 tons will be higher than at 40 tons. Also, the thrust may not be exactly zero, but we're discussing rules-of-thumb, not looking for exact answers.
Vref, on the other hand, varies with weight so that the L/D and glide angle are constant.