From: jfindley@cinci.nospam.rr.com
In article , jfmezei.spamnot@vaxination.ca
says...
>
> The term "Iterative development" has been drilled into me by the
> regular posters here.
>
> So I ask this in that context.
>
> SpaceX has by now plenty of experience with Falcon 9 and its 2nd stage,
> and with Dragon variants (2 generations, and second generations having
> both Cargo and Passenger versions).
>
> I can understand how the "iterative" part moved SpaceX move from
> building rockets (where it had experience) to building glorified flying
> grain silos. It had to learn how to work with steel, how to weld it so
> it doesn't rupture when filled with cryos etc.
>
> However, the experience it already had for "rocket" stuff like landing
> gear, thrusters etc should have been able to advance during the time
> SpaceX was learning to build grain silos.
I'm sure they've already tested the thrusters at McGregor Texas. IDK
about landing gear.
> So I am quite curious why the teams working on the project don't have
> proper landing gear yet, and thrusters still seem like experimental
> thinsg mountied outside of fuselage with some discussions still going on
> on what sort of fuel will be used.
Iterative development. The current test flights will provide data which
can be used to refine the landing gear design. Besides, the first
orbital attempt won't be landed on land anyway.
I'd bet gaseous methane and LOX for the thruster propellant. SpaceX has
been clear that is needed for the Mars ships.
> And how come thrusters would be bolted on the outside at this stage of
> development? Shouldn't plans already include the space needed for them
> inside fuselage for aerodynamic pruposes and ensuring thry don't burn up
> on re-entry?
Because inside is LOX or liquid methane. They have to be on the outside
(or inside the interstage). Aerodynamic fairings aren't needed for this
first Super Booster test article. I'm not sure it will even fly.
Static fires are planned though.
> It seems unreal to me that SpaceX would focus on one thing at a
> time and only now would start working on thrusters.
That's the very definition of iterative development. That's exactly how
Falcon was designed.
> You can't just tag on stuff
> as you progress because eventually, it needs to all integrated into a
> neat aerodynamic rocket that doesn't have components stick out.
Sure you can.
> Much thinking was put on selection of methane as fuel because of
ability
> to generate some on Mars. How come the selection of fuel for thrusters
> wouldn't have been done at same time?
It certainly did. They'll use gaseous methane and oxygen for the Mars
ships. That eliminates tanks for inert gas (e.g. helium on Falcon).
> As SpaceX has stopped testing the Starship in preparation for n
> orbital flight later this year, I would have expected the Starship
> to have advanced to a point where it is ready for orbital flight
> with its components having been tested. Can it really do orbital
> flighst and re-entry with externally mounted naked thrusters?
Starship is ready for an orbital flight attempt. TPS covered
aerodynamic surfaces have been spotted in Boca Chica. Again, the Super
Booster prototype being tested now isn't the one they'll use for the
orbital attempt. They'll likely have fairings over the thrusters for
the orbital attempt.
Jeff
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