JF Mezei wrote on Thu, 30 Aug 2018
11:24:52 -0400:

On 2018-08-30 07:10, Jeff Findley wrote:

That's my understanding. Conversion to cargo configuration will involve
taking out the seats, crew consoles, life support, and etc. Essentially
it means unbolting, unplugging, and removing components that simply
aren't needed.


And adding the structural supports for cargo. (aka glorified
shelves/racks or whatever).

However, if the insides of the Dragon are re-usable easily and not
damaged by a flight/landing, why go through the trouble of changing in
inside config from a crewed one proven to work to a cargo one ?


Because there are a lot more cargo flights than crewed flights.


It isn't just the "bolted on" consoles, but also all wiring harnesses.


If the wiring is 'built in' and not just strung all over Hell's half
acre you can just leave it in place after you unplug the consoles.


I wonder if Musk/SpaceX will ever explain what arguments were used to
decide that crewed shouldn't be re-usable as crewed.


Because even flying new they're cheaper than Boeing because Boeing
uses a ULA booster, so they can get NASA to pay to buy the Crew Dragon
new, which subsidizes the cargo side of things.


As far as the heat shield, does SpaceX just "spray" new ablative
material over existing used heat shield to bring it back to proper
thickeness, or does it strip the whole thing out and spray on a totally
new heat shield? Does either change the level of trust in its ability
to support crewed re-entry? (aka: heat shield with new top layer vs
totally new heat shield).


Neither one of those. The heat shield is thick enough to stand
multiple LEO reentries (something like 10) without any maintenance.
Some of it ablates away every flight, but not enough to require
replacement.


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