Isothermal LOX and propane tanks allow the propane density to rise to
728 kg/m3, approaching the density of kerosene with nearly the Isp of
methane. No fuel vapor boiloff makes for reduced fire hazards, too.
On 2018-02-13 11:08 AM, William Claybaugh wrote:
Is anyone aware of a careful comparison of LH2 vs. Propane fueled SSTO?
Hydrogen tanks generally weigh around 10% of the fuel mass whereas Propane tanks are closer to 1%....
Bill
On Tue, Feb 13, 2018 at 11:56 AM Rand Simberg <simberg@xxxxxxxxxxxxxxx <mailto:simberg@xxxxxxxxxxxxxxx>> wrote:
I'd hope that we learned from Shuttle that the key to reducing the cost
of access to space is not a massive government program.
On 2018-02-13 10:53, Keith Henson wrote:
> Henry Spencer wrote
>
> On Sat, 10 Feb 2018, John Dom wrote:
>>> ... Who knows where the Skylons would be by now if they got the
same
>>> help SpaceX got..
>
>> Probably not much farther than they are now, given that the help to
>> SpaceX
>> was hundreds of millions to produce flying rockets with flying
>> capsules on
>> top, while Skylon development is still forecast to cost tens of
>> billions and
>> there is no plan for a less-expensive demonstrator first. (Which puts
>> Skylon in the "need not be taken seriously" category, in my opinion,
>> since
>> nobody is going to spend that kind of money on an unproven concept.)
>
> Let's turn this around. What would it take for someone (governments
> most likely) to fully develop Skylon?
>
> The last time this happened was nuclear weapons during WW II. So it
> would take the moral equal of a war of survival. Is the threat to
> climate due to CO2 high enough for that to happen? I don't know, but
> there are not a lot of other carbon-free energy sources on tap.
>
> I am agnostic about how we transport parts into space for power
> satellites. Skylon, BFR, witches brooms, all the same to me. The
> critical thing is cost. If you can't get the cost per kW of
installed
> power to $2400 or less, then power satellites are a hard sell. At the
> current design point, that needs about $100/kg to LEO. I don't think
> rockets can reach that number, but if they can, we have the tools to
> solve the carbon and energy problems.
>
> Keith
>
> PS. The other option is to go to the moon or asteroids for
materials.