I have a feeling someone (perhaps SpaceX) will make a high performance
"upper stage" for starship.
"Old school" rocketry style probably H2/O2 maximal mass fraction kinda
deal.
Take the relatively benign ride up to LEO for minimal $ on a starship
then do a whole mess of plane changes etc and kick out ride share
passengers along the way into pretty much whatever orbits they want.
Or strap deep space payloads to the top of it and get to Jupiter in less
than a decade.
(I have the feeling the latter payloads are what would fund the development)
Some back of the envelope numbers, assuming the cargo stretched version
of starship exists you have a payload volume (for the cylindrical part
only, ex the nose cone) of 8m diam x 20m long. Thats 1000 cubic meters.
At 70kg/cubic meter that's 70 tonnes of hydrogen in LEO. Add 11 tonnes
of oxygen for a 6:1 ratio and you have 81 tonnes of propellant.
At 95% mass fraction (because why not, we are dreaming and starting in
LEO means we can cheat) and an ISP of 450, you have 13.5Km/s to play
with there.
Add a 20Tonne payload and you're at 6.5Km/s. That's a lot of ride share
satellites in a lot of orbits.
LEO really is half way to anywhere lol especially if it's cheap.
On 17/04/2023 3:52 pm, Bill Bruner wrote:
A Transporter style rack on Starship will threaten the business models for all of the expendable and partially expendable artillery rockets - whether they are small, medium or large.
"Threaten" might be an understatement.
B
On Sun, Apr 16, 2023 at 7:39 PM Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Sun, 16 Apr 2023, James Fackert wrote:
> The small launcher market seems to be much smaller and less
lucrative
> than projections indicated.
Much will depend on whether SpaceX stays in the ride-share
market. A lot
of the forecast small-launch demand is going there instead. If they
decide that it's too much trouble for too little return -- and it
wouldn't
be the first time they've abandoned the small-payload market! --
that will
change things.
Saturday morning's Transporter launch on Falcon 9 carried fifty small
payloads plus one more sizable one -- maybe a dozen small launches
worth
of small payloads. (Not fifty because some of them were packaged
together
or had other reasons for going up together, e.g. the three Hawks
operate
as a three-satellite formation and needed to start in the same orbit.)
Mind you, I also agree with Jim that the market is not as big or as
lucrative as some people thought, at least not at current
small-launch
prices.
Henry