A few quick sums:
If you neglect air resistance you have to start from 18,906 feet according to Newton.
(I remember this from a maths lesson in 1967 "If a plane flying at 19,000 at drops a bomb what speed does it hit the ground at? ignore the effect of air resisitance." I got to 1100 feet per second but the teacher wanted it in miles per hour and I got that bit wrong, which is why I remember it! Very irascible Scotsman was Laurie Andrew)
VnV