[ExI] rocke fuel was Re: SpaceX launch

[Adrian Tymes]

On Fri, Dec 10, 2010 at 7:50 AM, Eugen Leitl <eugen at leitl.org> wrote:
> On Thu, Dec 09, 2010 at 08:44:51PM -0800, Adrian Tymes wrote:
>> Could you use tungsten as a heat exchanger?
>>
>> Have an onboard energy source, optimized for heat generation instead
>> of thrust.  (Maybe even fission/radioactives, so long as they don't get
>
> http://en.wikipedia.org/wiki/Nuclear_thermal_rocket
>
> see "Risks".
>
> They're not that good http://en.wikipedia.org/wiki/Specific_impulse

The first article gives a specific impulse of 850 seconds for a simple
solid-core design.  The latter gives specific impulses of 250-450 for
modern chemical (solid or liquid fuel) rockets.  Yes, there are better
examples listed, but none that give 1G+ thrust.  (Fuel efficiency is
very desirable, but high thrust is required, for launching.  So we can
ignore any engines that do not give 1G+ thrust for that purpose, no
matter their other benefits, even though they may be superior after
orbit is achieved.)