Pictures but no words

I was trying to find out more about the Space-X booster return system, and
I am fully aware of apparently silent videos about it and showing it, but as
I cannot see these i wondered if there is a discussion of the concepts and
shape of the system the size and the methods used somewhere?
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!

"Brian Gaff" wrote in
:

I was trying to find out more about the Space-X booster return
system, and I am fully aware of apparently silent videos about it and
showing it, but as I cannot see these i wondered if there is a
discussion of the concepts and shape of the system the size and the
methods used somewhere?
Brian




http://www.space.com/22433-reusable-...-systems-dc-x-
infographic.html



http://www.space.com/32517-spacex-st...ng-sea-dragon-
launch.html


http://www.fool.com/investing/genera...acex-does-the-
impossible-again.aspx





port Canaveral webcam shows the rocket being unloaded from the barge
at times. (along with cruise ships of course)

http://www.portcanaveralwebcam.com/

In article ,
says...

I was trying to find out more about the Space-X booster return system, and
I am fully aware of apparently silent videos about it and showing it, but as
I cannot see these i wondered if there is a discussion of the concepts and
shape of the system the size and the methods used somewhere?

Not that I'm aware of, so I'll give this a quick shot. Bear with me
since things like this are hard for me to describe in text.

The entire two stage Falcon 9 Full Thrust is a cylinder 12 feet in
diameter and 230 feet high. It's really tall, but relatively small in
diameter so its individual (fully assembled and tested) stages can be
shipped via semi-truck (i.e. "wide/oversized load") instead of being
shipped by much more expensive means like many launch vehicles.

In a nutshell, the Falcon 9 first stage is about 2/3 of the height (I'm
eyeballing a picture for this number) of the launch vehicle and looks
more or less conventional. In rough terms, it is a long, skinny,
cylinder that is 12 feet in diameter and with 9 engines on the bottom
(one in the center with 8 around the outside). The engines are attached
to the stage via a thrust structure that SpaceX likes to call the
octoweb. Because this is so strong, it has four hardpoints built into
it, equally spaced around the bottom of the stage. These hardpoints are
where the booster sits when on the launchpad and are also where the
landing legs attach.

The landing legs number four (since they each attach to two adjacent
octoweb hardpoints at the bottom). The legs are roughly a very long
triangle whose short side attaches to the hardpoints at the bottom of
the stage and whose point is attached to the side of the stage. When
landing, the legs are forced outwards by very large pistons made up of
several nested cylinders, similar to an old style extendable portable
radio antenna. The pistons lock in place when fully extended.

The top of the stage comes back with the interstage adapter ring
attached (inside of that ring is where the upper stage Merlin engine
occupies space before stage separation). Attached to the outside of the
interstage adapter are four movable grid fins. for launch they are
folded (down) against the vehicle to minimize drag. When folded down,
they look like the end of an old school fly swatter with slightly bigger
square holes in the face of the swatter. Also, the face of the swatter
would need to be maybe 1/2" thick or more (instead of thin and floppy)
to look the same.

So when coming in for a landing, the grid fins are extended very high up
in the atmosphere and are movable so that they help keep the stage
stable during its descent. When the stage is getting close to the
ground, the landing legs are extended and locked and only the center
engine is firing at its lowest thrust level. The center engine gimbals
and the grid fins keep moving in order to stabilize the stage.

I really hope this helps. I'm an engineer, not a writer, so I'm used to
drawing things on a white board while describing them to other people.
If anything is unclear, just ask.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

In sci.space.station message -
september.org, Sat, 16 Apr 2016 13:40:38, Jeff Findley
posted:

I really hope this helps. I'm an engineer, not a writer, so I'm used to
drawing things on a white board while describing them to other people.
If anything is unclear, just ask.

You could add that there are (IIRC) three recovery burns; one soon after
separation, one around atmosphere entry, and the single-engine landing
burn. IIRC, the earlier burns use three engines. I think the three
burns apply both to the back-to-land and the out-at-sea recoveries. You
will probably recall the details,


--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Merlyn Web Site - FAQish topics, acronyms, & links.

In article id,
lid says...

In sci.space.station message -
september.org, Sat, 16 Apr 2016 13:40:38, Jeff Findley
posted:

I really hope this helps. I'm an engineer, not a writer, so I'm used to
drawing things on a white board while describing them to other people.
If anything is unclear, just ask.

You could add that there are (IIRC) three recovery burns; one soon after
separation, one around atmosphere entry, and the single-engine landing
burn. IIRC, the earlier burns use three engines. I think the three
burns apply both to the back-to-land and the out-at-sea recoveries. You
will probably recall the details,

Yes, there are three burns after stage separation.

The first "kills" the horizontal velocity away from the cape. For the
case of a landing at the launch site, this burn is much longer and
actually reverses the horizontal velocity vector, so that the stage can
make it back to the cape.

The second burn happens right before/during reentry to slow the stage
down vertically, so it does not reenter the earth's atmosphere too fast
and burn up/break apart. I believe SpaceX found out they needed this
burn "the hard way" and had a stage or two not make it through reentry.

The final burn is the landing burn, which is quite tricky. The thrust
to weight ratio of the very nearly empty stage is greater than one even
with the one center engine firing at its lowest thrust setting. So, it
has to be timed so that it can throttle up, as needed, and still end up
with zero vertical velocity at the precise point in space 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. Once on land,
and once on the barge. The first was on land and has been test fired
and partially disassembled (based on a picture Elon Musk Tweeted
yesterday showing the two stages in their new horizontal integration
facility located right before the ramp at KSC Pad 39-A (a former Saturn
V/shuttle pad which they are leasing from NASA).

The stage from the barge landing was transported on an over-sized load
trailer from Port Canaveral back to the same building yesterday. After
being moved from the barge to the port (vertically), it was inspected a
bit, the grid fins folded up, then its landing legs were removed. Two
cranes then lifted it, moved it into a horizontal position, then placed
it on the trailer for the trip back to KSC.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

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?

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

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.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

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
. @ .

In sci.space.station message
n.invalid, Tue, 19 Apr 2016 21:03:21, Dr J R Stockton reply1600@merlyn
..demon.co.uk.invalid posted:

In sci.space.station message -
september.org, Sat, 16 Apr 2016 13:40:38, Jeff Findley
posted:

I really hope this helps. I'm an engineer, not a writer, so I'm used to
drawing things on a white board while describing them to other people.
If anything is unclear, just ask.

You could add that there are (IIRC) three recovery burns; one soon after
separation, one around atmosphere entry, and the single-engine landing
burn. IIRC, the earlier burns use three engines. I think the three
burns apply both to the back-to-land and the out-at-sea recoveries. You
will probably recall the details,

Today - three-engine re-entry burn, no boostback burn, three-engine
barge landing burn : successful - burns according to
http://spaceflightnow.com/2016/05/06...-in-middle-of-
the-night-launch/.


--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Merlyn Web Site - FAQish topics, acronyms, & links.

In article id,
lid says...


Today - three-engine re-entry burn, no boostback burn, three-engine
barge landing burn : successful - burns according to
http://spaceflightnow.com/2016/05/06...-in-middle-of-
the-night-launch/.

Much more challenging landing. Musk tweeted 2x reentry velocity, 4x
reentry energy, and 8x reentry heating.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.