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Falcon 9 Delivers Dragon Into Orbit, Flubs Landing



 
 
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  #1  
Old December 6th 18, 12:06 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 1,761
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing


Falcon 9 Delivers Dragon Into Orbit, Flubs Landing
http://aviationweek.com/space/falcon...n-orbit-flubs-
landing

Note that's not my title, that's Aviation Week & Space Technology's
title. I LOL-ed because why don't they use this headline with every
Atlas V, Delta IV, Ariane V, Soyuz, Proton, and etc. launch? Because
every single one of them never even attempts to recover the firs stage.

Now obviously there was a failure. Musk tweeted that a grid fin pump
failed. You could see in the live stream video that the grid fin on the
right side of the camera's frame kept tilting to the right, but never
tilted back to the left. That triggered the stage's automatic abort
system, which kept the landing trajectory on a spot on the ocean instead
of redirecting towards the landing pad. That worked well. They do this
on every landing, including on the autonomous drone ship, so that if
anything goes wrong, it's not going to damage the landing facility (be
it fixed or floating). That happened to the core stage of the Falcon
Heavy on its first flight. It ran out of "starting fluid" for its
engines and splashed down hard instead of hitting the autonomous drone
ship.

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. All in all it landed very well (just in the ocean).
After the ocean landing, Musk Tweeted, "Appears to be undamaged and is
transmitting data. Recovery ship dispatched."

Last I heard on Twitter last night, they had the stage secured to at
least one ship and they were waiting for daylight (today) to resume
recovery operations. I'm not sure this is something they've planned for
in great detail, so how they get the stage back into port will be
interesting. Luckily, they're not very far away from port.

I still think it's funny that people focus so much on the landing when
that's gravy for SpaceX. The primary customer (this time NASA) doesn't
care if the landing succeeds or not, just that the payload (this time
Dragon) gets into the correct orbit. By all accounts, this was yet
another successful *launch* of Falcon 9.

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.
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  #2  
Old December 6th 18, 02:59 PM posted to sci.space.policy
Rocket Man
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Posts: 14
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

I wonder if it's useful to add a backup pump since this has never happened
before in almost 40 landings. They should first find the root cause of the
failure, maybe it's something minor and the pump itself. I doubt if a pump
system would fail if it was properly manufactured and installed over the
liftime of the stage.

"Jeff Findley" wrote in message
...

Falcon 9 Delivers Dragon Into Orbit, Flubs Landing
http://aviationweek.com/space/falcon...n-orbit-flubs-
landing

Note that's not my title, that's Aviation Week & Space Technology's
title. I LOL-ed because why don't they use this headline with every
Atlas V, Delta IV, Ariane V, Soyuz, Proton, and etc. launch? Because
every single one of them never even attempts to recover the firs stage.

Now obviously there was a failure. Musk tweeted that a grid fin pump
failed. You could see in the live stream video that the grid fin on the
right side of the camera's frame kept tilting to the right, but never
tilted back to the left. That triggered the stage's automatic abort
system, which kept the landing trajectory on a spot on the ocean instead
of redirecting towards the landing pad. That worked well. They do this
on every landing, including on the autonomous drone ship, so that if
anything goes wrong, it's not going to damage the landing facility (be
it fixed or floating). That happened to the core stage of the Falcon
Heavy on its first flight. It ran out of "starting fluid" for its
engines and splashed down hard instead of hitting the autonomous drone
ship.

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. All in all it landed very well (just in the ocean).
After the ocean landing, Musk Tweeted, "Appears to be undamaged and is
transmitting data. Recovery ship dispatched."

Last I heard on Twitter last night, they had the stage secured to at
least one ship and they were waiting for daylight (today) to resume
recovery operations. I'm not sure this is something they've planned for
in great detail, so how they get the stage back into port will be
interesting. Luckily, they're not very far away from port.

I still think it's funny that people focus so much on the landing when
that's gravy for SpaceX. The primary customer (this time NASA) doesn't
care if the landing succeeds or not, just that the payload (this time
Dragon) gets into the correct orbit. By all accounts, this was yet
another successful *launch* of Falcon 9.

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.



  #3  
Old December 6th 18, 06:01 PM posted to sci.space.policy
Niklas Holsti
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Posts: 65
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.

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .
  #4  
Old December 6th 18, 08:35 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,817
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

Jeff Findley wrote on Thu, 6 Dec 2018
06:06:49 -0500:



Luckily, they're not very far away from port.


It's not 'luck' in this case. The 'abort landing' case is designed to
do that.


I still think it's funny that people focus so much on the landing when
that's gravy for SpaceX.


Yeah. Let's examine the successful landings of other space boosters.
Oh wait...


The primary customer (this time NASA) doesn't
care if the landing succeeds or not, just that the payload (this time
Dragon) gets into the correct orbit. By all accounts, this was yet
another successful *launch* of Falcon 9.


Yep. Recovery is only a secondary goal. Yep, everything went
perfectly with the launch. Only recovery had a glitch. With 33
successful recoveries under their belt, it's going to take a good long
time for anyone to match SpaceX's record.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw
  #5  
Old December 6th 18, 08:39 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,817
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

"Rocket Man" wrote on Thu, 6 Dec 2018
14:59:44 +0100:

I wonder if it's useful to add a backup pump since this has never happened
before in almost 40 landings.


No and I doubt anyone is even considering that.


They should first find the root cause of the
failure, maybe it's something minor and the pump itself. I doubt if a pump
system would fail if it was properly manufactured and installed over the
liftime of the stage.


You figure out what sort of failure the pump had. If it's something
other than a 'one off' failure, you make the pump more robust against
that type of failure.


--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world."
-- Mary Shafer, NASA Dryden
  #6  
Old December 6th 18, 08:42 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,817
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

Niklas Holsti wrote on Thu, 6 Dec 2018
19:01:58 +0200:

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.


The same way any other single engine booster controls roll, I would
think. The engine gimbals.


--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world."
-- Mary Shafer, NASA Dryden
  #8  
Old December 7th 18, 01:11 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 1,761
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

In article ,
says...

"Rocket Man" wrote on Thu, 6 Dec 2018
14:59:44 +0100:

I wonder if it's useful to add a backup pump since this has never happened
before in almost 40 landings.


No and I doubt anyone is even considering that.


They should first find the root cause of the
failure, maybe it's something minor and the pump itself. I doubt if a pump
system would fail if it was properly manufactured and installed over the
liftime of the stage.


You figure out what sort of failure the pump had. If it's something
other than a 'one off' failure, you make the pump more robust against
that type of failure.


That's one way to handle it. Since they're recovering the stage,
they'll be able to tear down the failed pump and hopefully discover the
failure mode.

That said, Elon Musk has already tweeted that they'll likely add a
second hydraulic pump. On BFR/BFS they'll want multiply redundant
systems so it makes some sense to apply the same methodology to Falcon 9
as a learning experience.

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.
  #9  
Old December 7th 18, 01:15 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 1,761
Default Falcon 9 Delivers Dragon Into Orbit, Flubs Landing

In article ,
lid says...

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.


Some landings start with one engine, then three engines, then go back to
one engine. If that was the case here, gimbaling the outer two engines
gives you roll control authority.

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.


Agreed. If the landing burn was indeed one engine, then that's where
the majority of the de-spin would had to have come from.

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.


Agreed.

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


Agreed. The guidance control system performed very well. In the video
taken from the stage, you could see at least one reaction control
thruster firing almost constantly in order to counter the aberrant grid
fin torque.

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.


Possibly ice from around the LOX fill connection? That would seem to
make sense given the size and shape of the ring of ice.

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.
 




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