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Old December 6th 18, 06:01 PM posted to sci.space.policy
Niklas Holsti
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Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

On 18-12-06 13:06 , Jeff Findley wrote:

Also, the stage managed to land very well on the ocean (as can be seen
in a video posted by an observer on social media). SpaceX also released
the on board camera footage from the stage which showed that once the
landing burn started, the engines were able to negate the roll caused by
the stuck grid fin.


I thought the landing uses only one engine, therefore probably the
center engine -- then how can the engine control roll? I don't understand.

In the videos it seems that the roll rate does not decrease much during
the landing burn, until just before and mainly after the landing legs
are deployed. Deploying the legs moves mass out from the roll axis and
therefore decreases roll rate, independently of the engines.

All in all it landed very well (just in the ocean).


It was significantly tilted at touch-down. Perhaps one or two legs would
have crushed their crushables if it had been a hard surface.

But I'm impressed that it managed to land at all with that roll rate.

Before the entry burn, at about 29:45 in the SpaceX launch video, a
white, spiky ring of some sort came off the area around the left-hand
grid-fin in the on-board video. Commentators described it as some frozen
condensation, but it looked curiously regular for that... I haven't
seens anything like that in earlier launches.

By all accounts, this was yet another successful *launch* of Falcon 9.


Yes indeed.

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Niklas Holsti
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