[AR] Re: Flying to Orbit with Hydrogen?
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Thu, 26 Dec 2019 11:29:36 -0800
On Wed, Dec 25, 2019 at 10:10 PM Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
snip
Vertical-launch hydrocarbon rockets, at first glance, ought to be better
for ozone than a wing-supported LH2 airbreather. They'll certainly spend
less time in the upper atmosphere, and should put out less water vapor
than a hydrogen burner and less nitrogen oxides than an airbreather.
It turns out that the chemistry is important. Skylon engines run rich
and the hydrogen suppresses NOx formation. The same trick is used to
take the NOx out of power plant exhaust. So Skylon generates almost
no ozone-damaging NOx on the way up. The NOx it makes is during
reentry on the way back.
(Although a careful look at the numbers would be needed to make sure.)
NOAA article is here:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016EF000399
The NOx problem from hydrocarbon rockets is due to air (nitrogen)
being entrained by the engine plume. How bad the NOx problem is for
hydrocarbon rockets has not been analyzed.
Keith
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