In article ,
Scott Lowther wrote:
Hybrids are not an unreasonable choice. The one limitation, for an
operational vehicle, is that loading a new fuel grain -- inherently a
large, clumsy object -- is distinctly less convenient...

Oh, not necessarily. The hybrid grains are inert solid objects... keep
'em stored in a rack.

Kerosene stores very nicely in quite ordinary tanks. And you don't need
to manufacture it.

No power required for refrigeration...
The guys who deal with the fuel do not need specail
cyrogen protection suits...

None required for kerosene. That sort of thing *is* required sometimes
for the oxidizer... but hybrids too use a liquid oxidizer.

spills of hydrocarbon fuels do not need to be
mopped up and leeched out of the ground prior to the contamination
reached groundwater.

Odd how most airports have little trouble with this, thanks to making
modest efforts to avoid spills and contain the ones they do get.

Also, the fuel tanks will not need to be periodically cleaned out or
inspected; there will be little risk of dirty sediment building up and
clogging things.

Except in the oxidizer plumbing, of course, which means that the cleaning
and inspection still has to be done.

Replacing a
hydrid fuel grain could be, if designed right, the job
of two guys and ten minutes, using tools available at any Home Depot.

I don't recall Home Depot selling forklifts, although perhaps I haven't
looked in the right area. These grains won't be lightweight.

Don't forget that you have to get the remains of the old grain out first.

Fueling an airliner usually takes one guy about the same length of time
with no tools.

And in this case, these two guys can be relatively low-tech, and thus
lower pay and overhead than the several guys needed for RP-1 maintenance
(and certainly far cheaper than LH2 maintenance guys).

The airliner fueling crew usually doesn't have a PhD either. DC-X didn't
have a squad of people devoted solely to pouring fuel into the tanks, and
that was with LH2.

Since the solid
fuel won't spill and is damned unlikely to catch fire, storage costs and
facility insurance rates *should* be lower.

The insurance people will probably be far more worried about fires in the
oxidizer storage facility anyway, as indeed they should be.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |