The converse of this is that the first bit of velocity you save pays off handsomely. Every multiple of the exhaust velocity that you save nets you a factor of e

The converse of this is that the first bit of velocity you save pays off handsomely. Every multiple of the exhaust velocity that you save nets you a factor of e savings in mass ratio. Additionally, getting out of the soup of the lower atmosphere improves the average efficiency of your engine. Again, this is a bigger deal, relatively speaking, when you’re saving the first bit of velocity off the top, as you’re multiplying on a larger launch vehicle.