Leaning tower of falcon 9

The LA Times is reporting today's landing attempt was unsuccessful:

SpaceX launches two satellites, but drone ship landing is unsuccessful.
http://www.latimes.com/business/la-f...nap-story.html

Elon Musk Verified account
�@elonmusk
Looks like thrust was low on 1 of 3 landing engines. High g landings v
sensitive to all engines operating at max.
https://twitter.com/elonmusk/status/743097337782763521

My opinion, in order to land successfully in a consistent fashion SpaceX
will have to give the F9 hovering ability.

High g landings are endemic to a "hover-slam" landing, more commonly
referred to as a "suicide-burn", more accurately referred to as "land or
slam", since without hovering ability, you only get one chance at it. You
either stick the landing on the first try, or you crash and burn.

Bob Clark


----------------------------------------------------------------------------------------------------------------------------------
Finally, nanotechnology can now fulfill its potential to revolutionize
21st-century technology, from the space elevator, to private, orbital
launchers, to 'flying cars'.
This crowdfunding campaign is to prove it:

Nanotech: from air to space.
https://www.indiegogo.com/projects/n...ce/x/13319568/
----------------------------------------------------------------------------------------------------------------------------------
"Dr J R Stockton" wrote in message
nvalid...

In sci.space.policy message -
september.org, Mon, 6 Jun 2016 07:14:24, Jeff Findley
posted:

In article id,
says...

In sci.space.policy message -
september.org, Fri, 3 Jun 2016 15:48:38, Jeff Findley
posted:

3. Getting the thing vertical when the barge is moving in the ocean
would be "challenging".

I think not. One need only pump ballast within the barge in the
compensating direction. It is getting the thing perpendicular to the
deck that should be difficult.

You could do this, but I would think doing so would screw up the ability
for the tug to get it back to port in a timely fashion.

Many seagoing vessels have been towed to port, often in extreme
conditions, with very considerable lists. Even the "Flying Enterprise"
was nearly saved : https://en.wikipedia.org/wiki/SS_Flying_Enterprise.


Since the vast majority of the mass of an empty stage is at the bottom,
actual tilt is relatively unimportant.

In other words, "if it ain't broke, don't fix it". So what if it was
leaning? It made it back to port safely, which is what matters.

Yes; I was only challenging the 'would be "challenging"', not advocating
that it would be _useful_ to do it.


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



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

In article ,
says...

The LA Times is reporting today's landing attempt was unsuccessful:

SpaceX launches two satellites, but drone ship landing is unsuccessful.
http://www.latimes.com/business/la-f...nap-story.html

Yes, but the launch *was* successful, so the paying customer is happy
and the Falcon flight program will continue. :-)

Elon Musk Verified account
?@elonmusk
Looks like thrust was low on 1 of 3 landing engines. High g landings v
sensitive to all engines operating at max.
https://twitter.com/elonmusk/status/743097337782763521

He also Tweeted that SpaceX has already been working on ways to handle
this situation. In other words, it's just like the launch that "ran out
of hydraulic fluid" for the grid fins. Even before that failure, they
were working on increasing the fluid available for landings.

My opinion, in order to land successfully in a consistent fashion
SpaceX will have to give the F9 hovering ability.

I respectfully disagree. Again, this is a known issue that was already
being worked on. This is a *test flight program*. SpaceX has yet to
even refly a stage! Problems are expected during a test flight program.
You develop fixes for problems as they become known. In this case, the
problem was already known and a fix was already in the works. This was
not an "unknown unknown" this time. It was a known risk that they took
in order to fly the mission for the customer without making them wait
for a landing fix they largely don't care about.

The customer just wants their satellites in the proper orbit. That
mission was accomplished.

High g landings are endemic to a "hover-slam" landing, more commonly
referred to as a "suicide-burn", more accurately referred to as "land or
slam", since without hovering ability, you only get one chance at it. You
either stick the landing on the first try, or you crash and burn.

You only got one chance at final approach and landing a shuttle orbiter,
but they were all successful (with arguably a few close calls). So
that, in and of itself, doesn't disqualify the hover slam approach.
Besides, the Falcon 9 first stage is unmanned, so nobody was killed.

Remember, "perfect is the enemy of good enough". If they can make this
"good enough", they can learn from it and incorporate all of the lessons
learned in their next generation vehicle. Not everything has to be
fixed in version 1.X of a vehicle. Version 1 just has to be "good
enough". Version 2.0 can contain major upgrades and will hopefully be
even better.

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 article om,
says...

On 2016-06-15 18:02, Jeff Findley wrote:

Remember, "perfect is the enemy of good enough". If they can make this
"good enough", they can learn from it and incorporate all of the lessons
learned in their next generation vehicle. Not everything has to be
fixed in version 1.X of a vehicle. Version 1 just has to be "good
enough". Version 2.0 can contain major upgrades and will hopefully be
even better.


There is one issue not being mentioned: right now, they are testing the
limits of the vehicle.

They may come to the conclusion that for high performance launches,
there is too much speed and not enough fuel to make a reliable landing.
Say they manage 50% of landings (for sake of discussion).

Possibly, but I doubt it. Out of the last three GTO missions (high
performance) they successfully landed two out of three. That's not bad,
IMHO, considering how early in the test program it is and the fact that
Musk has said repeatedly that these post GTO mission landings are very
high risk because they really are at the very edge of the capabilities
of the stage.

What is the cost of the attempted landing (drone ship, crews, helicopter
to video it etc) as well as the cost of repairing the drone ship after
the big explosion. Economics may dictate that for such flights, it is
best to ditch in ocean. Aka: value of 5 recovered rockets then cost of
trying to land 10 rockets, and repairing damage from the 5 failed ones.

Ditching in the ocean was tried before the barges were available. Every
one was lost, even the ones that successfully "soft landed" on the ocean
surface. They all broke apart due to wave action. There is a reason
ships have very thick hulls. Liquid fueled launch vehicle stages do not
have thick hulls. The solid fueled shuttle SRBs survived because they
had very thick steel casings.

But we're not there yet because it is too soon to establish the
economics of landing the rocket.

The economics of recovering and ref-lying a vehicle is a narrow view.
Widen your view to the overall company's economics...

At this point, reducing pressure on the manufacturing capacity is quite
important, even if these first few re-flights don't "save" any money.
Also, getting the stages back for inspections is a good thing. It
allows for more engineering data than dropping it in the ocean and
letting it sink, which is the alternative that every other current US
launch vehicle provider uses.

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.

"Jeff Findley" wrote in message
...

In article om,
says...

On 2016-06-15 18:02, Jeff Findley wrote:

Remember, "perfect is the enemy of good enough". If they can make this
"good enough", they can learn from it and incorporate all of the
lessons
learned in their next generation vehicle. Not everything has to be
fixed in version 1.X of a vehicle. Version 1 just has to be "good
enough". Version 2.0 can contain major upgrades and will hopefully be
even better.


There is one issue not being mentioned: right now, they are testing the
limits of the vehicle.

They may come to the conclusion that for high performance launches,
there is too much speed and not enough fuel to make a reliable landing.
Say they manage 50% of landings (for sake of discussion).

Possibly, but I doubt it. Out of the last three GTO missions (high
performance) they successfully landed two out of three. That's not bad,
IMHO, considering how early in the test program it is and the fact that
Musk has said repeatedly that these post GTO mission landings are very
high risk because they really are at the very edge of the capabilities
of the stage.


True, but I think JF's overall point is close to the mark and mirrors what
you're saying. Ultimately, they don't need to land 100% of them
successfully, just "enough" of them. At some point they may say "this is
good enough".

What is the cost of the attempted landing (drone ship, crews, helicopter
to video it etc) as well as the cost of repairing the drone ship after
the big explosion. Economics may dictate that for such flights, it is
best to ditch in ocean. Aka: value of 5 recovered rockets then cost of
trying to land 10 rockets, and repairing damage from the 5 failed ones.

Ditching in the ocean was tried before the barges were available. Every
one was lost, even the ones that successfully "soft landed" on the ocean
surface. They all broke apart due to wave action. There is a reason
ships have very thick hulls. Liquid fueled launch vehicle stages do not
have thick hulls. The solid fueled shuttle SRBs survived because they
had very thick steel casings.


Agreed. If they hit the ocean, write them off. But again, that should be a
pretty low number.

But we're not there yet because it is too soon to establish the
economics of landing the rocket.

The economics of recovering and ref-lying a vehicle is a narrow view.
Widen your view to the overall company's economics...

At this point, reducing pressure on the manufacturing capacity is quite
important, even if these first few re-flights don't "save" any money.
Also, getting the stages back for inspections is a good thing. It
allows for more engineering data than dropping it in the ocean and
letting it sink, which is the alternative that every other current US
launch vehicle provider uses.


This is one of the more overlooked values of the shuttle program: the value
of the engineering data.
Never before had we reflown engines like that. Never before had we learned
about stresses on airframes.
Never before had we learned (and unfortunately ignored) about burn-through
on large SRBs.


So yeah, this was a loss for SpaceX, but their approach takes this into
account. They're using every flight as an opportunity to learn.

Jeff

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

In article ,
says...

The LA Times is reporting today's landing attempt was unsuccessful:

SpaceX launches two satellites, but drone ship landing is unsuccessful.
http://www.latimes.com/business/la-f...nap-story.html

Elon Musk Verified account
?@elonmusk
Looks like thrust was low on 1 of 3 landing engines. High g landings v
sensitive to all engines operating at max.
https://twitter.com/elonmusk/status/743097337782763521

My opinion, in order to land successfully in a consistent fashion SpaceX
will have to give the F9 hovering ability.

SpaceX released a video showing how close this landing was. Apparantly
the stage ran out of LOX right above the deck. You'll want to take a
look because it actually looks very close to hovering in the video.

https://www.reddit.com/r/spacex/comm...on_twitter_loo
ks_like_early_liquid/

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.

Jeff Findley wrote:

In article ,
says...

The LA Times is reporting today's landing attempt was unsuccessful:

SpaceX launches two satellites, but drone ship landing is unsuccessful.
http://www.latimes.com/business/la-f...nap-story.html

Yes, but the launch *was* successful, so the paying customer is happy
and the Falcon flight program will continue. :-)


Right. And since right now he's charging as if he's not going to get
the stages back, SpaceX is also happy (enough).


Elon Musk Verified account
?@elonmusk
Looks like thrust was low on 1 of 3 landing engines. High g landings v
sensitive to all engines operating at max.
https://twitter.com/elonmusk/status/743097337782763521

He also Tweeted that SpaceX has already been working on ways to handle
this situation. In other words, it's just like the launch that "ran out
of hydraulic fluid" for the grid fins. Even before that failure, they
were working on increasing the fluid available for landings.


And even if they don't, if it works only part of the time they still
come out ahead as long as the cost of recovery and refurbishment is
lower than a new booster.

My opinion, in order to land successfully in a consistent fashion
SpaceX will have to give the F9 hovering ability.

I respectfully disagree. Again, this is a known issue that was already
being worked on. This is a *test flight program*. SpaceX has yet to
even refly a stage! Problems are expected during a test flight program.
You develop fixes for problems as they become known. In this case, the
problem was already known and a fix was already in the works. This was
not an "unknown unknown" this time. It was a known risk that they took
in order to fly the mission for the customer without making them wait
for a landing fix they largely don't care about.

The customer just wants their satellites in the proper orbit. That
mission was accomplished.


I agree with you. Not only would building in 'hover' for recovery
invalidate all the work they've already done (essentially start over
and crash some more until the landing software was right), but it
would require an expensive redesign of the engines. Since SpaceX can
already compete on price with the existing system, it's just not worth
the cost.

This is the problem with a lot of people who just think about 'theory'
and push for performance. They lose sight of the economics of the
thing.

High g landings are endemic to a "hover-slam" landing, more commonly
referred to as a "suicide-burn", more accurately referred to as "land or
slam", since without hovering ability, you only get one chance at it. You
either stick the landing on the first try, or you crash and burn.

You only got one chance at final approach and landing a shuttle orbiter,
but they were all successful (with arguably a few close calls). So
that, in and of itself, doesn't disqualify the hover slam approach.
Besides, the Falcon 9 first stage is unmanned, so nobody was killed.

Remember, "perfect is the enemy of good enough". If they can make this
"good enough", they can learn from it and incorporate all of the lessons
learned in their next generation vehicle. Not everything has to be
fixed in version 1.X of a vehicle. Version 1 just has to be "good
enough". Version 2.0 can contain major upgrades and will hopefully be
even better.


SpaceX essentially gets the recovered stages for 'free', since they
charge the customer as if the stage is going to be expended. There
are at least three different cost models that would allow SpaceX to
lower costs based on booster recovery. All of them work just fine
(given analysis of costs and recovery success rates) with an
'imperfect' percentage of successful recovery attempts.


--
"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

Jeff Findley wrote:

In article om,
says...

On 2016-06-15 18:02, Jeff Findley wrote:

Remember, "perfect is the enemy of good enough". If they can make this
"good enough", they can learn from it and incorporate all of the lessons
learned in their next generation vehicle. Not everything has to be
fixed in version 1.X of a vehicle. Version 1 just has to be "good
enough". Version 2.0 can contain major upgrades and will hopefully be
even better.


There is one issue not being mentioned: right now, they are testing the
limits of the vehicle.

They may come to the conclusion that for high performance launches,
there is too much speed and not enough fuel to make a reliable landing.
Say they manage 50% of landings (for sake of discussion).

Possibly, but I doubt it. Out of the last three GTO missions (high
performance) they successfully landed two out of three. That's not bad,
IMHO, considering how early in the test program it is and the fact that
Musk has said repeatedly that these post GTO mission landings are very
high risk because they really are at the very edge of the capabilities
of the stage.


There will be missions where the size of the payload precludes
recovery (because you can't reserve the landing fuel and get the
performance the customer needs). They have a pretty good idea of
where that line is. For anything else, given the cost of building a
new stage, it is probably always going to be cheaper to try to recover
the stage than not even bother with the attempt. After all, you've
already paid for the recovery hardware ("Of Course I Still Love You")
and the staff required are still on salary, so the marginal cost of
attempting a recovery is low.


What is the cost of the attempted landing (drone ship, crews, helicopter
to video it etc) as well as the cost of repairing the drone ship after
the big explosion. Economics may dictate that for such flights, it is
best to ditch in ocean. Aka: value of 5 recovered rockets then cost of
trying to land 10 rockets, and repairing damage from the 5 failed ones.

Ditching in the ocean was tried before the barges were available. Every
one was lost, even the ones that successfully "soft landed" on the ocean
surface. They all broke apart due to wave action. There is a reason
ships have very thick hulls. Liquid fueled launch vehicle stages do not
have thick hulls. The solid fueled shuttle SRBs survived because they
had very thick steel casings.


And even the SRBs required a lot of work before they could have been
reflown.

The only real 'delta cost' for recovery is the fuel to move the barge
(which you already own) plus flight hours on any aircraft (and you
don't HAVE to video the thing - SpaceX does that for the 'cool
factor', Musk recognizing that a lot of us geeks (like the ones he has
working for him) like to see it). Damage from an 'explosion' of the
stage to the landing ship is probably unlikely. Remember, these
things are designed to have firing rocket engines impinge on them.
Despite how flashy the explosion might be, that's probably tougher on
the landing ship than any uncontained explosion of a stage.


But we're not there yet because it is too soon to establish the
economics of landing the rocket.

The economics of recovering and ref-lying a vehicle is a narrow view.
Widen your view to the overall company's economics...

At this point, reducing pressure on the manufacturing capacity is quite
important, even if these first few re-flights don't "save" any money.
Also, getting the stages back for inspections is a good thing. It
allows for more engineering data than dropping it in the ocean and
letting it sink, which is the alternative that every other current US
launch vehicle provider uses.


Not only that, but as long as the cost of FUEL for the recovery
systems plus necessary refurbishment is less than the cost of
manufacturing a new stage, recovery is a big incremental economic win
regardless of which cost model(s) are used to recover the cost of
recovery.

Sorry, about all the 'recovery' in that statement, but I'm still in
recovery. :-)


--
"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

"Fred J. McCall" wrote in message
...

The only real 'delta cost' for recovery is the fuel to move the barge
(which you already own) plus flight hours on any aircraft (and you
don't HAVE to video the thing - SpaceX does that for the 'cool
factor', Musk recognizing that a lot of us geeks (like the ones he has
working for him) like to see it). Damage from an 'explosion' of the
stage to the landing ship is probably unlikely. Remember, these
things are designed to have firing rocket engines impinge on them.
Despite how flashy the explosion might be, that's probably tougher on
the landing ship than any uncontained explosion of a stage.

Yeah, someone I was talking to suggested that an explosion might cause a lot
of damage, but I tend to doubt it.

You already have a pretty solid deck built for the Falcon 9 to "crash" onto
and it's built to withstand an engine blast.

So sure, maybe a handrail or two and maybe a camera, but as long as you're
hitting the deck, my guess is most of the effort is sweeping the debris off
after.
--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

JF Mezei wrote:

On 2016-06-18 07:30, Fred J. McCall wrote:

There will be missions where the size of the payload precludes
recovery (because you can't reserve the landing fuel and get the
performance the customer needs).

There are obviuos cases where ditching stage 1 is happening, and there
are borderline cases. That "borderline" area right now is those GTO
launches.


Wrong. It is always worthwhile to try to recover a stage if there is
ANY chance of recovery.


For anything else, given the cost of building a
new stage, it is probably always going to be cheaper to try to recover
the stage than not even bother with the attempt.

Accountants will decide this once SpaceX has enough data points and once
its software has matured. Right now, it appears there is still much
fine tuning of software possible. But once optimized to the max, they
will know pretty well what the limits are in terms of having enough fuel
to reliably land.


They pretty well know that now.

After all, you've
already paid for the recovery hardware ("Of Course I Still Love You")
and the staff required are still on salary, so the marginal cost of
attempting a recovery is low.

That is for accountants to decide. There is the cost of refurbishing the
barge after an explosion.


I seriously doubt that's a big cost because I seriously doubt an
uncontained explosion on a landing pad is going to damage anything
other than some surface mounted support equipment.


Also, the marginal cost of deploying vs leaving in port may not be so
small. If engines require maintenance based on hours of operation, then
the more you use it, the most it costs to maintain. And while crews are
at sea, they may cost much more than on land (meals, overtime etc). It
is also not clear whether SpaceX owns the support ships that we never
see or whether it leases them "on demand".


Engine maintenance on a ship is, relatively speaking, pretty damned
cheap. Keeping it in port costs money in port fees. There aren't a
lot of people involved, so paying and feeding them is down in the
noise. There is only one other ship involved.

Again, if there is even a 10% chance of recovery attempting the
recovery is a 'win'.


Accountants would have such numbers by now. (including cost of refurb
after landing failure).


Well, no, they won't. This hasn't been done enough and a refurbed
booster has never been reflown.


And if the cost of refurbishing the barge is high, accountants may ask
engineers to have rocket decide whether landing is possible or not (fuel
remaining vs speed/altitude) or have the software wilfully ditch next to
the barge if it thinks it can't make a safe landing due to insufficient
fuel.


So you take all the expense of a recovery and then toss $18 million in
the water. Makes no sense.



And even the SRBs required a lot of work before they could have been
reflown.


SRBs landed in salt water.


Which was irrelevant. Just the impact messed them up, which is what
was being discussed. Salt water doesn't hurt an SRB casing all that
much, given that there's no engine in there that you're trying to
recover.


Nobody is suggesting refurbishing a stage1 that falls flat on its belly
in the ocean.


Nobody sane is suggesting trying to recover a stage from the water,
period. You can't get them down soft enough.


With regards to revenues for flights on new rockets, it would not
surprise me if negotiations included a rebate if stage1 is recovered.
(or recoverable because of easier flight profile).


That's certainly one funding model that could be used. I can think of
several others that could all be used independently or in combination.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

JF Mezei wrote:

On 2016-06-18 11:47, Fred J. McCall wrote:

If you have reduced NET revenue when launching payload on a refurbed
rocket then you're doing it wrong. There might not be ANY reduced
revenue when launching on a refurbed rocket, depending on what the
reliability of refurbed stages is


We can turn this around: if NASA demands new stages for the flights it
buys, SpaceX can charge a premium for that. Hence more revenues.


That's the same thing and if you're getting lower NET revenue for
reflown stages then you are doing it wrong.


Once reliability of refurb engines is proven and even NASA doesn't
demand new stages for its flights, then yeah, the price to launch will
not be affected by whether a stage is reused or not.


Do you know what NET means?


And one has to consider the possibility that a "new" stage may have half
its engines new and half used.


Why the hell would they do that? The idea is to not have to take the
stage apart like that.


I doubt there's much 'repair' needed after a stage explosion.

Accountants know, we don't.


Accountants don't know ****.



Now, at some point my success rate could be so low that it's not worth
the fixed costs and I have no idea what those fixed costs amount to.


But this applies on a mission profile basis. Some types of missions
would have higher reliable landings, while others have too high a risk
of explosion to bother trying to recover. And SpaceX doesn't yet have
enough data poimts to draw such a line.


Do you know what "fixed costs" mean? Fixed costs are costs that are
FIXED regardless of what you do.


And for now, they try all of them to establish those data points and
fine tune the software to move that line even higher to be able to
recover more of the stages.


You really don't understand what's going on and you don't seem willing
to listen when someone tries to tell you.



It's always worthwhile to attempt a recovery of any stage that has any
chance of recovery if you're going to maintain the infrastructure to
recover any of them.


It depends on how much its costs to refurbish the stage. Something which
SpaceX hasn't done yet.


Non sequitur. Go back and read what I said.


Remember that the shuttle was originally pitched as requiring little
maintance between flights, but turned out differently.


Yeah, it was pitched that way WHEN IT WAS AN INITIAL DESIGN CONCEPT.
Nobody believed that by the time they had the final design.

Falcon 9 isn't a 'paper bird'. It's flying hardware.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn