JF Mezei wrote on Tue, 1 Jan 2019
22:33:04 -0500:

On 2018-12-30 19:46, Fred J. McCall wrote:

SpaceX has a pretty damned good idea of where the lower threshold is
for number of reuses before major refurbishment is required.


They do?


Yes, they do.


What the maximum number of times a bloc, 5 has been re-used so
far ?


Three, I think. If you knew anything at all about engineering you'd
know how irrelevant that question is.


Any commercial customers lined for for the 9th launch of a Falcon 9 yet?


Oh, pull your head out of your ass! With around two dozen launches
per year and the dozen or so Block 5 first stages in existence, your
question amounts to asking if someone has manifested a flight at least
five years from now. No, they haven't, because nobody manifests
flights that far in advance. See what I mean about you saying
egregiously stupid ****?



The
'equation' doesn't particularly change, since it's always been an
assumption that some launches will require expending the vehicle.


Say for sake of discussion that SPaceX can launc Falcon9 10 times.

When you have a "performance requirememt won't allow landing"
requirememnt, you use a Falcon 9 that has done 9 launches, and it is
ditched on its 10th launch. This way, you don't lose any potential
flight on that rocket.


Well, you'd certainly LIKE to do it that way, but if you held to that
you wouldn't be able to launch any such missions until sometime after
2025 or so. Not reasonable. So you launch on the next rocket in the
queue that meets the timeline. These days that means you are almost
certainly using either a new booster or one with a single launch on
it.


This is quite different from DoD requiring that SpaceX uses a brand
spanking new Falcon9 that is ditched with less than 1 flight (since
re-use factors in the multiple lighting of engines for launch AND landing).


Not really, no (see above), and the number of launches requiring such
performance is small.


If SpaceX uses its remaining production capability for Falcon9 to build
stages for DoD that are never re-used, that doesn't leave many Falcon9s
in stock that can be used and re-used for affordable commercial launches.


Don't be silly. SpaceX can easily produce a dozen cores a year. Their
estimate is that if the put on a second shift and push a bit they can
produce around four dozen cores a year. They currently have ten Block
5 cores in inventory. At the current rate there won't be more than
3-4 such launches per year. So the inventory will grow by half a
dozen or more cores each year of production. USAF is planning a
launch on Falcon Heavy, which has the capacity for such launches in
reusable mode, which would eliminate that 3-4 expendable launches per
year.


If DoD allows the use of used Falcon9s, then SpaceX can do a number of
commercial launches on a stage and then finish that stage's life with
non re-usable DoD launch, and that makes a huge financial difference for
SpaceX which needs to build far fewer stages to get the same job done.


It's not just DoD that puts up heavy payloads, just by the way.
Commercial vendors do it, too.



You're obviously too thick to understand WHY a vehicle would be
expended on a launch.


In this particular case, because a lawsuit was involved for SpaceX to
get this launch, all bets are off on the real reasons for it.


Horse****. First, I'd like a cite for your claim that THIS LAUNCH was
awarded because of a lawsuit. Second, one can look at the mass of the
satellite and the required orbit and have a very good idea of the
'real reason' for it being an expendable launch. It's not magic.


As Mr
Findley pointed, contract was signed at a time SpaceX was trying but had
not yet demonstrated re-use.


Irrelevant. Once again, look at the mass of the payload and the
required altitude and inclination of the orbit.


Also, should it succeed (which it did), the
Dod would have had to setup procedures in the contract to ensure it can
"clean" the landed stage of any possible military secrets inside. So
requiring it be ditched in ocean would be much simpler and risk free.


More horse****. It's the FIRST STAGE. It neither knows nor cares
anything about the payload, so there is no scope for 'military
secrets' on the first stage. Do you even stop to think before you
type?


Remember also that if contract was signed prior to Block5 being in
production, it also means that the increased capacity/thrust it brought
would not have been required to launch that satellite, so using Block5
may have brough enough spare capacity to allow a landing. But since
contract stipulated no landing, SpaceX complied.


Please cite the contract language that stipulates no landing. Block 5
performance is less than 10% better (engine thrust is improved by
about 8%). Please cite the contract date. Right now you're just
flapping your arms and insisting you can fly.


IT could very well be a true performance limitation. But I am not 100%
sure of it


Yeah, math is hard.


Consider this: if Musk planned Falcon9 to be reusable 10 to 100 times,
but most of the launches are to be capacity limited and require
ditching, there wouldn't be much re-use done and that would change the
financials of that project a LOT.


Consider this. MOST launches are within the capacity of the vehicle
in reusable mode. Only a small number are not. In fact, the GPS
launch could PROBABLY have been done by Block 5 in reusable mode. USAF
wanted margin available in case something went wrong.


So I really suspect that commercial
launches to geosync will allow landing and re-use.


Some yes and some no. Payload mass matters. For example, ArabSat
6-A, which is manifested for the first quarter of next year, will go
to geostationary orbit on a Falcon Heavy because Falcon 9 just doesn't
have the grunt to get it up there.


Launching to half of
that should have allowed it even more (unless GPS satellite was very
very heavy).


You just really don't bother to even find out the facts before you
start flapping your arms, do you? The GPS birds are heavy (4400 kg)
and to high inclinations.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn