JF Mezei wrote:

On 2017-11-04 11:43, Jeff Findley wrote:

From above:
NASA said the Dragon spaceship assigned to the December launch
is the same capsule that flew to the station in April 2015 and
returned to Earth a month later.

So roughly 6-7 months turn around. Which isn't bad for a capsule that
splashed down in salt water.


Uh, something wrong with your math there. May 2015 to December 2017
is a little bit more than "6-7 months". There is no way to know what
the 'turn around' actually was. I doubt it took 30 months.


I wonder how this will pan out with crewed Dragons. Will they open the
hatch in water to extract crews ASAP (like for Apollo) or will they want
to lift it up and land it on a ship/barge before opening hatch (possible
even rinsing it with fresh water before).


Given that the intent is for it to be reusable, I would doubt they'll
be opening hatches while it's in the water unless it's sinking and
there's an emergency. Reentry accuracy of Dragon V2 is much better
than old capsules and it will land virtually on top of the recovery
platform. Unlike the government, SpaceX doesn't have the US Navy to
manage the recovery. The contract requires them to provide all
recovery facilities with the exception of SAR operations for
emergencies, which will be provided by Detachment 3, 45th Operations
Group, USAF.


Once Dragon V2 starts to fly, I wonder how many SpaceX will need to
build for each of the cargo and manned configs to meet NASA's needs and
turn around times.


Figure it out. It's not that hard. Take your shoes off if you need
to. Figure six-ish resupply missions a year plus two to four crew
exchange flights a year plus one docked as a 'lifeboat; call it a
dozen capsules required a year. They can presumably use Dragon V1
'reflown' capsules for cargo until they have enough V2 hardware on
hand to cycle it through. If they can refurbish a Dragon V2 capsule
in less than two years, they'll need around another dozen of them to
keep the pipeline full. As you shorten the refurbishment time the
number of required 'additional' capsules goes down by around one a
month for every month less than two years you can recycle them in.


Or will SpaceX keep the assembly line going at slow rate because it is
easier to do that than to build a batch of Dragons, produce none for
5-10 years, then get an order for new batch ?


In 10 years their plan is to have shifted to BFR Spaceship for this
stuff. However, they'll almost certainly keep the manufacturing line
going, since they intend to use these for other things than just
supporting NASA. Dragon V2 also isn't fully reusable. There are
parts (like the service module) that you don't get back.


Will crewed taxi flights be on a regular 3 month flight schedule (with
some crews skipping the return to stay 6 months) or will there be
variations in the launch schedule from 3, 4 and 6 months ?


That's up to NASA.


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