David Spain wrote:


Perhaps you can explain the small dip in the curve given for Vs
in Figure 1 on page 2 in the NASA Tech Note linked to below:

http://www.klabs.org/history/reports...1970023342.pdf

In the curve for Vs it appears it actually is *reduced* for
approx 25 seconds after launch before rising above its initial
value at s=0. We're speculating its due to early rocket motion
due to first stage engine gimbals?

Drag as it passes through the sound barrier?
Drag decreases once a object is in supersonic flight, which is why
fighter pilots do a bit of a power dive while approaching Mach 1, so as
to get into supersonic flight as quickly as possible.

Pat