[AR] Re: Reaction Engines' Sabre Rocket Engine Demo Core Passes

  • From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
  • To: Arocket List <arocket@xxxxxxxxxxxxx>
  • Date: Sun, 17 Mar 2019 19:55:56 -0400 (EDT)

On Sun, 17 Mar 2019, Keith Henson wrote:

...and second, figuring out if the rocket traffic for a significant
power satellite construction rate would wipe out the ozone.  This has
been done for Skylon, but it's a hydrogen burner and (burning rich)
makes almost no NOx on the way up.

As far as I know, there's nothing magic about burning hydrogen that helps with this -- in fact, hydrogen may actually be a bit worse for the ozone layer than hydrocarbons, because there's more water vapor in the exhaust. (The stratospheric chemistry in question happens mostly on the surface of ice crystals, so more water injected into the stratosphere -- which is normally very dry -- is not good news.)

This is also an area where rockets win over airbreathers, because running the air through the combustion system is rather more worrisome for NOx formation than just having the exhaust jet emerging into air.

Henry

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