Drag is quite significant at 40,000 ft. An airplane doing merely 0.8M requires
enormous thrust to maintain speed at that altitude.
On Feb 28, 2021, at 9:55 AM, Dr Edward Jones <RocketPioneer@xxxxxxxxx> wrote:
Thank you. Now suppose the single-stage balloon launch has an overall
mass fraction of 0.90 ... Air launched at 40,000-ft ... drag goes from
"nil" to "nada," correct?