In article ,
says...

On 2018-12-29 18:02, Jeff Findley wrote:

Soldiers in battle would depend on the new GPS III satellites.

A single satellite with additional features does not make those
additioanl features useful because you can't triangulate with those
extra features with only 1 satellite.

This is the very first of the Block III satellites. They include many
improvements to prevent jamming, improve accuracy, and etc. And, since
this is a DOD satellite, perhaps this block includes other "features"
that aren't openly discussed that are critical to war-fighters.

The satellite will become part of the standard GPS constellation
broadcasting the public signals like other GPS satellites and will be
included in the almanach and ephemeris broadcasts. Adding and removing
GPS satellites has been done many times before so this isn't a
"critical" thing.

Once this new satellite is accompanied by other Block 3, then there will
be times where there will be sufficient new GPS satellites visible to a
soldeier to enable whatever new military features have been added.

I really suspect the "critical" nature is more a question of needing to
test this new generation of satellites before you launc the rest of the
constellation.

Suspect all you want. DOD disagrees with you. I'll side with DOD on
this one.

DOD is currently specifying new Falcon 9 hardware only. DOD has not
certified already flown Falcon 9 first stages for DOD use.

Consider the lawsuits resulting from DoD originally gifting the launch
contract to buddies at ULA. DoD would be hurting ULA if it allowed
SpaceX to sell affordable launch services on re-usable launchers since
that would put ULA out of business. So their write contract specs to
ensure the SPaceX costs are as high as the specs can make them. This
makes it easier for ULA to continue to win contracts with the same specs
(everything new, use only once etc)

This makes zero sense. Check when SpaceX won this contract. Also, ULA
didn't even bother bidding on this one (DOD made a *huge* stink about
that). ULA wanted to "save" its very limited number of DOD allocated
RD-180 engines for far more profitable DOD launches.

Also, check the date when SpaceX won this contract. How far along was
SpaceX with landings and reuse? Please put some facts into your
"reasoning".

And with the new Secretary of Defence expected to be ex-Boeing VP, one
can expect the "swamp" to continue to steer contracts towards ULA
instead of more affordable/competitive services, and only give token
launches to SpaceX and Blue Origin (eventually) once in a while to give
the appearance of conpetition.

Again, ULA didn't even bother to bid on this launch. That's on ULA and
on Congress for finally growing a pair and telling ULA they can't use
Russian engines on Atlas V.

Do you have a cite which says exactly when they plan on stopping Falcon
9 first stage production? I certainly don't.

I'd have to go back through all the insults McCall sends me to sift
through it.

I'll take that as a no.

It is possible that when the initial BFR/BFS schedule was announced,
bridging launches between then and start of BFR/BFS commecial flighst
would have required far fewer Fakcon9s at which point pre-building them
and shuttong down production was more realistic. Or just Elon Musk doing
some marketing theatricals.

Also back then, they didn't have those military contract requiring new
launchers each time. So that changes the equation.

As you may recall, I was blasted for stating that re-usability of
Falcon9 had not been proven yet. And it was in that context where I
didn't believe that they could shut down Falcon9 production because once
they had enough they could just re-use them until BFR/BFS was launching
payloads.

You'd better check your dates on these things. SpaceX, especially Elon
Musk, states aspirational goals all the time.

My aspirational goal is to ride into at least LEO on a spacecraft before
I die. Are you going to come back at me in a few years, when I'm still
on the ground, and tell me I was lying when I stated that goal?

If you had a quote from Shotwell with an actual date, that would hold
*far* more weight than a Tweet or offhand comment by Musk. Musk knows
where he wants to go, but hard schedules are clearly not his forte.

From what has been reported, BFR/BFS is being built at a different
facility, so I would think Falcon production could most certainly
continue in parallel (at least as far as facilities are concerned).

One of the arguments that had been made was refocusing resources/budgets
towards BFR/BFS so produce enough Fancon9s to bridge the gap and then
move all budgets to BFR/BFS. I suspect this was reviewed when you
consider that Falcon9s provide the funding for BFR/BFS development.

You're muddling this up. Research and development is *not* the same as
production!

SpaceX has frozen the design of the Falcon 9 and Falcon Heavy at the
Block 5 model. This has been openly stated by SpaceX on several
occasions. Therefore, there will be no more significant research and
development work done on Falcon series of launch vehicles.

Production, however, will absolutely continue for some time to come
because BFR/BFS hasn't even started flying, let alone proven itself yet!
SpaceX still has both external customers with contracts to launch on
Falcons. So they need to build more Falcons. Also, internally SpaceX
needs to start launching a lot of Starlink satellites before the FCC
deadline.

In conclusion, there will be plenty of opportunities for Falcon to
continue to fly for at least the next 5 years, IMHO.

The point is that all of the research and development teams are now
focusing on BFR/BFS. That's precisely why we keep seeing substantive
changes to the design, because the engineers are actually putting a lot
of R&D effort into the design. There was an announcement recently that
there has been a significant change to the Raptor engine design (no
details yet). All of this change just shows that BFR/BFS is nowhere
near done with research and development.

I believe this launch was to a much higher inclination than due east
from KSC (55 degrees inclination according to the article below).

From 28", is there a huge performance difference launching north east to
55° vs launching due east and then steering to circularize at 0°
latitude over equator? Both require basically 28° correction from a due
east launch.

I'm not awake enough to explain orbital mechanics to you. If you want
to know the answers, "do the math" yourself.

Maybe, if BFR/BFS is as successful as planned. That's not a given. The
BFS "hopper" hasn't even flown once, let alone the full up BFR/BFS.

But ! But ! it wasn't so long ago that it was a given, that the tanks
had been fully tested and anyone not believing this (me) was blasted and
insulted to smitereens. So now, people are starting to see that building
the largest ever rocket stage and spaceship capable of holding 100
people may p]ossibly be so delayed and changed that it may not happen on
schedule and project may get scaled back ?

Clearly SpaceX had not done enough development work on exactly how
BFS/Starship would reenter. They've now done enough work to realize
that the design would work better with stainless steel as the material
in order to reduce the amount of thermal protection required for
reentry. That's an engineering trade-off.

At this point it's not clear if SpaceX will use composite tanks on the
BFR/Super Booster (or whatever they're calling the first stage). All we
know for certain is that they've changed the material for the upper
stage (BFS/Starship) to a 300 series of stainless steel. The pictures
of the "hopper" out in Texas are pretty damn shiny, so I'm guessing
stainless steel.

If I were an engineer, I'd use the same material in the first stage just
for the commonality. But who knows. Maybe they'll stick with
composites because the first stage really doesn't experience much
heating on reentry because it's staging at suborbital velocities.

Jeff
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