[AR] Re: Mini-rocket to space?

  • From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
  • To: Arocket List <arocket@xxxxxxxxxxxxx>
  • Date: Mon, 1 Mar 2021 17:46:19 -0500 (EST)

On Mon, 1 Mar 2021, roxanna Mason wrote:

      Drag is quite significant at 40,000 ft...

Right and the SR-70 flys fine at 100KFt...

Not quite -- SR-71 service ceiling was 85,000ft. That's where it ran out of lift at normal max speed, Mach 3.2. Going slightly faster was possible in special circumstances, but wouldn't gain you more than another few thousand feet. (The pilot's manual was almost completely declassified a number of years ago, see <https://www.sr-71.org/blackbird/manual/>, and its contents shot down a lot of overenthusiastic earlier speculation.) Still a lot higher and thinner than 40,000, though...

...and most meteors burn up at even higher alt.

Much higher -- they start being visible at 80-120km, and the small ones disintegrate up there. But that's thermal effects more than drag. Drag starts to be significant for small solid ones around 70km, although that's at very high speeds.

Henry

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