In article ,
says...

On 2019-04-30 14:10, Jeff Findley wrote:

I'm pretty sure they're totally independent. The pairs of SuperDracos
are fully independent from each other.

I believe this is correct. It gives the system some redundancy to have
these separate.


Considering current role of Super Dracos as being potentially useful
only during launch, and hopefully never used, wouldn't it make more
sense for them to share the weight of fuel with the dracos?

No. Dracos are likely much lower pressure than Super Dracos. It's much
simpler to have separate tanks in this case.

aka: if all goes well at launch, the fuel is used by dracos during
on-orbit operations. And if Super Dracos is used during launch, you're
not going to need the fuel for dracos isn't you're not going to orbit.

The intent was to use the Super Dracos for vertical landing on a nominal
mission. NASA nixed that, so we're left with them being there with no
operational use on a nominal mission. But that's the case with Boeing's
Starliner capsule as well, as far as I can tell, so Dragon 2 isn't
unique in this regard.

I could understand separate fuel tanks in a context where the Super
Dracos would be used for every landing. (if fuel not used for launch
abort, it is then needed for normal landing and vice versa).

That was the original intent, but SpaceX development is focused on
Raptor and Starship right now. Dragon 2 is done with development.
There are just a few issues to close out (admittedly this anomaly during
the Super Draco vibration / acoustic ground test is a big one to
handle).

Were powered landings ruled out during Dragon 1 such that Dragon2 design
started off with powered landings already out of equation, or did they
start designing it for powered landings and then it was ruled out ?

Powered landings were never in the plan for Dragon. It was only
designed to splashdown in the ocean under parachutes.

Jeff
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