On 16-04-21 13:03 , Jeff Findley wrote:
In article ,
lid says...

On 16-04-20 13:32 , Jeff Findley wrote:

Yes, there are three burns after stage separation.
...
The final burn is the landing burn, which is quite tricky. ...
... when its
landing gear hit the landing pad at (hopefully) a low enough vertical
and horizontal velocity (nearly zero) so it doesn't go "splat" like it
has on a few landings.

This whole sequence has been successful exactly twice.

I would have said "exactly three times". Didn't one of the barge-landing
attempts go well up to the end of the sequence you describe, and the
landed stage then fell over only because one of the landing legs failed
to lock in the extended position?

True, the landing looked like it was going to be successful when it
first touched down. But, falling over, splitting open, and burning to a
crisp isn't exactly a successful landing. You wouldn't call the landing
of an airliner whose landing gear collapsed upon touchdown successful if
the aircraft subsequently careened off the runway, caught fire, and
killed everyone on board.

Of course not, but the "sequence" you were (as I thought) discussing --
throttling the single Merlin engine running during the final burn, and
touching down exactly -- worked on that occasion. So the "pilot flying
the airliner" made a perfect landing; it wasn't the pilot's fault that
someone had forgotten to tighten a nut in the landing gear... or
whatever was the equivalent reason for the stage's leg giving way (IIRC,
jamming by ice was one suspected reason).

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .