Gordon D. Pusch wrote:

Keith Harwood writes:

Yup. Suppose, for example, such a material was used to make, say,
pressure vessles that mught contain such things as, say, rocket
propellants.

For any reasonable strength of material, the amount of additional energy
that can be stored by pressurizing the tanks is negligible compared to the
chemical energy stored in the propellants themselves. About all you will
do by pressurizing the tanks is to allow you to eliminate the mass of the
turbopumps and drive turbines, which is likely to be marginal compared to
the additional mass of high-pressure propellant tanks. Pressure-fed
rockets _may_ be justifiable on the basis of lower cost or higher
reliability, but are =VERY= unlikely to provide significantly better
performance than pump-fed rockets.

I was thinking that the unobtainium that had sufficient tensile strength
with low mass to build a beanstalk could also be used to make pressure
vessels that are very much lighter than those from presently existing
materials and, indeed, would be lighter than existing unpressurised tanks.
My consideration was the mass savings from no pumps and from the tankage
itself. It hadn't occurred to me to even consider the energy stored in the
pressurisation.

My point was simply that the material that made the beanstalk feasible
compared to conventional rocketry would help make rocketry more competitive
against a beanstalk.

(PS, sorry about the deplorable typing my previous post.)