Evan:
Thanks, I had missed this.
I find myself wondering what an advisor would have said if Henry II (of
England) had asked for an iPhone: is SSTO a technology that is more
economic in future rather than today?
Because multiple analyses show SSTO at a limit price around $50 per Kg., it
seems likely to be the preferred answer in a century or so when demand has
reached levels that justify that solution. The question I’m—in part—trying
to answer is whether a significant investment today can move forward the
time when SSTO flight rates are justified.
In the timeframe of SSTO viability it appears probable that “peak oil” will
be reached and thus that simpler hydrocarbons may be favored over highly
refined ones (because simple hydrocarbons can be relatively cheaply derived
from organic feedstock). Thus Propane over Kerosene.
Bill
On Wed, Feb 14, 2018 at 1:00 PM Evan Daniel <evanbd@xxxxxxxxx> wrote:
On Wed, Feb 14, 2018 at 1:55 PM, William Claybaugh
<wclaybaugh2@xxxxxxxxx> wrote:
If we are considering tripropellants, then the Hydrogen would presumablybe
used as the coolant (optimizing Isp by altitude is achieved by varyingthe
percentage of Hydrogen and Hydrocarbon being burnt). But that stillleaves a
potential coking problem at the hydrocarbon injectors and upstream aftera
shutdown; a hydrocarbon that evaporates w/o residuals seems likely to be
better choice than one that does not (like kerosene) if one is looking to
avoid a post firing purge.
Part of XCOR's approach was to use a kerosene that evaporated without
residuals.
Doug's post on 3/29/17 to this list includes a photo and AIAA paper:
https://www.freelists.org/post/arocket/LPL-IPA-Effects-on-Copper,5
And a selected quote that the archives don't seem to display:
"...dry-residue-free fuels are strongly advisable, so that greasy
films cannot be created by fuel spills. We have had good results in
using 99% isopropyl alcohol as fuel; we even use the same supply for
the cleaning solvent to prepare the oxidizer plumbing. In the
transition to kerosene based fuels, we have settled on a grade of
kerosene equal or even superior to RP-1, a multiply-distilled product
with no non-volatile components. Conventional Jet-A or JP-4 has too
many high molecular weight species, aromatic compounds, and [too much]
sulfur content to be used in a long-life regeneratively cooled rocket
engine where low coking is mandatory. The jet fuels leave long lasting
residues, incompatible with oxygen, if spilled."
Evan Daniel