Falcon 9s have a limit to how many times they can be reused, and, for the last flight of a booster they don't make it land (in one piece), and instead use all the fuel to help the payload. That way they can put much bigger payloads to orbit (https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems gives the payload for both partially reusable and expended full thrust)

Out of the 23 falcon 9 launches in 2018, 8 had no attempt at recovery

My question is, when launching an expendable falcon 9, how much of the recovery system does Spacex remove?

I'm assuming they probably remove the titanium grid fins since they are very expensive and hard to manufacture,
but what about:

  • The landing legs?
  • The fluid used to power the hydraulics to deploy the fins and the legs?
  • The nitrogen gas in the thrusters used to turn the booster around or to stabilize it?
  • The nitrogen gas thrusters themselves?
  • All the other expensive or heavy hardware used to land the boosters?

Is it worth it removing all these?

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    $\begingroup$ Have they reached the flight limit for the boosters? They were expending older versions of the booster that were harder to prepare for reflight. $\endgroup$ – Loren Pechtel Jun 16 '19 at 3:44
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    $\begingroup$ And one I can address directly: The hydraulic fluid was simply fuel. They had a separate tank of it they could pressurize and use to operate things, after it had done so it simply emptied into the fuel tank. $\endgroup$ – Loren Pechtel Jun 16 '19 at 3:45
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    $\begingroup$ I doubt they will remove the cold gas reaction system because that can be used during ascend as well. $\endgroup$ – GittingGud Jun 18 '19 at 11:10

We have seen on past expendable launches that they do not fly with the legs and the grid fins. Those are the easily visible external features.

Still to be determined are the less obvious internal features.

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    $\begingroup$ Other things I can think of: hydraulic systems for grid fins, RCS (?), extra engine-ignition pyrophilic fluid for relights $\endgroup$ – CourageousPotato Jun 16 '19 at 3:11
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    $\begingroup$ Wasn't there a launch recently where a recovery was possible given the fuel budget, but the drone ship wasn't available, and they did a simulated landing in the ocean instead? If I remember correctly, that booster had the grid fins but not the landing legs, which seems to suggest that the recovery system is pretty modular and flexible. Also, IIRC, they attempted to recover the booster from sea but were unable due to weather, and had the Navy scuttle it instead. $\endgroup$ – Jörg W Mittag Jun 16 '19 at 18:09
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    $\begingroup$ Ah, those were CRS-14 and GovSat-1 I was thinking about, and those did have the legs. $\endgroup$ – Jörg W Mittag Jun 16 '19 at 18:25

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