[AR] Re: Reaction Engines' Sabre Rocket Engine Demo Core Passes
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx, Power Satellite Economics <power-satellite-economics@xxxxxxxxxxxxxxxx>
- Date: Sun, 17 Mar 2019 08:49:51 -0700
On Sat, Mar 16, 2019 at 10:17 PM Evan Daniel <evanbd@xxxxxxxxx> wrote:
The original presentation for the SpaceX BFR called for $500/kg to
Mars surface, including LEO refueling, with the capital cost of the
transit ship being a very large fraction of that. They didn't break
out the numbers in detail to give a LEO payload cost estimate, but I
infer it was much lower than $500/kg.
Numbers since have gone up, and sizes and flight rates down, but I
think if you asked SpaceX to project out to those volumes you'd see
numbers below $100/kg to LEO. I don't think Skylon is unique in that
fashion.
They were unique at the time, but otherwise, I agree with you. There
are two problems beyond cost, first is getting Elon Musk to let SpaceX
rockets be used for power satellites, something he is strongly opposed
to, and second, figuring out if the rocket traffic for a significant
power satellite construction rate would wipe out the ozone. This has
been done for Skylon, but it's a hydrogen burner and (burning rich)
makes almost no NOx on the way up.
Rand Simberg <simberg@xxxxxxxxxxxxxxx> wrote:
And as with any SSTO, Skylon would suck for off-nominal (higher
inclination/altitude) missions.
Agree entirely. Fortunately, low equatorial LEO is where the cargo goes.
David Summers <dvidsum@xxxxxxxxx> wrote:
Just to check my understanding of what you are saying, that follows only if
the payload mass to empty stage mass fraction is small, right? So if you
had an SSTO that arrived on orbit as 50% payload then the performance
difference would be much smaller.
Skylon's expected payload is 15 tons out of a takeoff mass of 325
tons. So a little under 5%.
Of course, as Bill showed a while back you could also use that same
technology base to make an even better two stage to orbit vehicle.
"Better" by what metric? The problem with two stages is the cost of
getting the pieces back to the launch point.
cc to power satellite economics
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