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Were liquid boosters on Shuttle ever realistic?



 
 
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  #21  
Old October 27th 17, 02:33 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default Were liquid boosters on Shuttle ever realistic?

JF Mezei wrote:

On 2017-10-26 16:27, Fred J. McCall wrote:

And they have to be "certified" for a magnitude (or multiple
magnitudes in the case of something like BFR) more fill and drain
cycles if they're supposed to be reusable.


When dealing with composites, while you certify based on your tests,
must it not be engineered to be refillable an infinite number of times?


Nothing is "refillable an infinite number of times". Your question
isn't comprehensible, so it can't be answered.


Yes, you engineer to a maximum pressure (validate with destructive
test). But when you certify a tank for X refills, isn't it more akin to
stating that after X refills, you saw no defects develop? (as opposed to
stating that defects appear after each fill, but tank will hold until it
has Y defects).


It's a combination of both of those and you don't just build something
random and then determine things by test. You design to performance
targets.


Carbon fibre structures quickly lose their strength/integrity as soon as
there is a defect.


That depends on the defect. Nothing goes from pristine to
instantaneous failure.


A carbon fibre bike won't last long if a crack
develops. Likely won't get you home because with each bump on road, the
crack will get much worse.


Fortunately I don't think any carbon bikes are used in SpaceX
boosters.


--
"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
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  #22  
Old October 27th 17, 11:17 AM posted to sci.space.policy
Jeff Findley[_6_]
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Default Were liquid boosters on Shuttle ever realistic?

In article ,
says...

Jeff Findley wrote:

In article ,
says...
Actually they haven't. Superchilled RP1 drives up costs in order to
improve performance. Going for reusability drives up manufacturing
costs and design costs because you have to make things that can be
used dozens of times without attention (so you need better materials
and tighter designs without pushing for extra performance, figure out
some way to avoid 'coking' on an RP1/LOX engine, etc). It's the
normal engineering evolution of launch vehicles that was stalled while
most payloads were government.


As far as engines go, this isn't really true. All liquid fueled engines
are designed to be fired multiple times, at least on the test stand.
That's how they're qualified. Henry Spencer used to say (paraphrasing
here), there is absolutely nothing fundamental about a liquid fueled
rocket engine that makes it expendable.


Well, actually it is. You go into engine design knowing how many
'refires' the engine needs to stand. If it needs to stand 3 with some
safety margin, the robustness required is a lot less than if it needs
to stand up to 36 of them with the same safety margin. That is going
to drive up manufacturing costs (which you hopefully get back through
the savings by reusing hardware).


A more reusable engine also helps to make qualification testing cheaper.
An engine that can be fired multiple times without tear downs is far
cheaper to certify than one designed to be "expendable" and therefore
needs to be torn down more frequently because the margins are thinner.

Making rocket engines single use is a false economy. Merlin seems to
bear this out considering how many times it's been test fired
(individually and on Falcons). The more test firings you can do, the
better confidence you have in the engine. As far as I know, no Merlin
1D has failed in flight, despite the crazy high number flown (10 on each
Falcon 9 flight). On top of that every one of those first stage engines
is test fired not only in Texas, but on the pad as well.

Falcon 9 has had a couple of quite spectacular failures, but neither was
due to a Merlin.


Same goes for tanks and plumbing. They pretty much have to be
"certified" for a certain number of fill and drain cycles even if
they're "expendable" in order to account for tanking tests, aborts, and
etc.


And they have to be "certified" for a magnitude (or multiple
magnitudes in the case of something like BFR) more fill and drain
cycles if they're supposed to be reusable.


Agreed. But is it really that much more expensive to certify, say, 100
drain and fills for a "reusable" versus, say, 10 for an "expendable"?
This is especially true if you consider you can certify it for 10, start
flying the vehicle, then continue the (ground) certification process
while you're flying the first generation (test) hardware. Aircraft
programs are sometimes run like this. You don't have to certify
everything for max number of cycles before you start flying (and making
money).

At any rate, my point is that liquid fueled stages are always reusable,
in principle. SpaceX has shown that with a small delta in cost and
effort, entire first stages can be recovered intact (without being
dunked in salt water).

Not trying to reuse liquid fueled first stages in this day and age seems
daft.

Solids on the other hand are single use, excepting for complete tear
down to component parts accompanied by extreme cleaning.


Solids are expensive for what they bring to the table when compared to
liquids, even if you fully expend all hardware. I really don't
understand ULA's love affair with them.


Also agreed.

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.
  #23  
Old October 27th 17, 11:27 AM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 1,491
Default Were liquid boosters on Shuttle ever realistic?

In article . com,
says...

On 2017-10-25 07:13, Jeff Findley wrote:

On top of that, both SpaceX and Blue Origin are pursuing reusability
with a tenacity never before seen in the industry (space shuttle SRBs
and orbiters were refurbished after flight over many months, so they
don't really count). That will be the next step towards even cheaper
access to space.



In fairness, SpaceX is likely at the same stage now that NASA was when
it had flown a Suttle orbiter 2 or 3 times. Doing costly turn-around
examinations in order to gauge how much work will really be needed in
the future.


Not at all. The first turn-around cost SpaceX much less than half the
cost of building a new one. That was not true of shuttle SRBs which
cost about as much to refurbish the steel segments as it would have cost
to simply build new steel segments. SRB refurbishment was *always*
hideously expensive and time consuming. SpaceX is now starting to build
Block 5 first stages which incorporate improvements which will enhance
reusability, so costs will continue to drop.

Until it has reflown enough stages, AND SpaceX releases some number of
the work/costs involved in turning stages around "in production", nobody
outside of SpaceX know how cost effective turning stages around is.


Again, SpaceX has publicly stated the first reuse of a first stage cost
less than half the cost of building a new one. That's significant and
will only get better with time and changes to the hardware (e.g. Block
5).

It may very well be a no brainer either way (eg: 50% cheaper than new
stages or 75% cheaper than new stages ) So the question becomes how MUCH
will SpaceX revolutionlize launch industry, not whether it will or not.


This I can agree with. SpaceX already has very low prices even before
taking into account reuse.

But there is one extremely important point that you have not mentioned.
Customers are already choosing to fly on refurbished first stages
because it gets their payloads in orbit faster than waiting for a new
first stage to be built. Time is money to a satellite company since a
comsat makes zero revenue sitting on the ground waiting to be launched.
See the news stories this week and last.

Assuming a fixed production rate, reuse gets payloads into space faster
than building new stages. Reuse also will improve reliability in the
long term due to inspections and subsequent hardware improvements.
These are both secondary effects but both help to lower overall costs to
the customer.

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.
  #24  
Old October 27th 17, 06:21 PM posted to sci.space.policy
Greg \(Strider\) Moore
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Posts: 584
Default Were liquid boosters on Shuttle ever realistic?

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

"Greg \(Strider\) Moore" wrote:

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

There is no such thing as assembly line production 'spewing out'
rocket engines. It made sense to use Merlin engines because the idea
was to have three identical cores for Falcon Heavy, sort of like what
Delta IV Heavy does. In the event, Musk found they couldn't do that
and that they couldn't just use three Falcon 9 cores for Falcon Heavy.
The side boosters are now different from the central 'core'.


What are the differences? Last I knew the side boosters for the primary
flight are B1023.2 and B1025.2 (i.e 2nd flight for those two boosters)


It's mostly got to do with mechanical loading. The side boosters are
close (but not an exact match) for what they fly on Falcon 9. They're
only slightly modified so as to be able to take structural loading
from the attachment points on the sides rather than straight down
through the center of the core.


I can see that. As you say, must be fairly slight. Interesting though.

The center booster requires a lot
more structural work to stand loads, both the side loads from the two
attached boosters and the increased load on the front of the booster
from the second stage and payload.


Yeah, I figured the central core would be different.

Musk himself has said that he
doesn't necessarily expect the first launch attempt to reach orbit and
would consider it getting far enough away to avoid pad damage a win.


Yeah, he's doing a good job of lowering expectations. I'm pretty sure he's a
lot more confident than that, or else he wouldn't risk a launch.

Look at how many Falcon 9 launches failed before they got a success.


You mean 0?
Landing took some tries, but the launches were successful.


According to Musk, Falcon Heavy was "shockingly difficult" to develop.
It was originally supposed to use fuel cross-feed among the three
cores, but that proved too difficult and was dropped.


Yeah. That I knew. And makes sense. Gets some advantages, but it's a feature
that can be added on later.

It was
originally supposed to be three 'standard' Falcon 9 cores (with Falcon
9 eating the additional structure) but now the center booster is
different from the side boosters. Yes, it really is rocket science...


Ayup.
Or at least rocket engineering.



--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
https://www.amazon.com/Disaster-Resp...dp/1484221834/

  #25  
Old October 27th 17, 06:48 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,489
Default Were liquid boosters on Shuttle ever realistic?

"Greg \(Strider\) Moore" wrote:

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


Look at how many Falcon 9 launches failed before they got a success.


You mean 0?
Landing took some tries, but the launches were successful.


I read somewhere in passing that the first three launches failed. I
now think that author confused Falcon 9 with Falcon 1.


--
"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
  #26  
Old October 27th 17, 07:13 PM posted to sci.space.policy
Greg \(Strider\) Moore
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Posts: 584
Default Were liquid boosters on Shuttle ever realistic?

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

"Greg \(Strider\) Moore" wrote:

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


Look at how many Falcon 9 launches failed before they got a success.


You mean 0?
Landing took some tries, but the launches were successful.


I read somewhere in passing that the first three launches failed. I
now think that author confused Falcon 9 with Falcon 1.

Yeah, Falcon 1 definitely had teething problems.

But to be honest, I did have to look it up just to make sure I remembered
the Falcon 9 correctly.

That said, the first 3 flights did all have test payloads, "just in case".

There have only been two Falcon 9 "launch" failures (i.e. ignoring all the
landing failures).
The first was the inflight one where I believe a strut collapsed caused
structural damage.
The second was of course the fueling test on the pad.



--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
https://www.amazon.com/Disaster-Resp...dp/1484221834/

  #27  
Old October 27th 17, 11:49 PM posted to sci.space.policy
Greg \(Strider\) Moore
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Posts: 584
Default Were liquid boosters on Shuttle ever realistic?

"JF Mezei" wrote in message
web.com...

On 2017-10-27 06:27, Jeff Findley wrote:

Again, SpaceX has publicly stated the first reuse of a first stage cost
less than half the cost of building a new one.


Is that PR speak or "auditor" speak? The first reflown stage was not
the first landed stage. Say the first reflown stage uses some engines
that were refurbished from other recovered stages, and their reburb
costs billed to "R&D". Not saying this is what happened, but just one
way to skew numbers for good PR.


My understanding, but I have no reference for it is engines stay with the
booster.


Customers are already choosing to fly on refurbished first stages
because it gets their payloads in orbit faster


But lets wait until SpaceX actually delivers on a launch rate. Not
doubting it will, but the sample size right now is too low to allow
conclusions.


Actually delivers? They've done 15 flights this year and expect at least 4
more (I'm not counting Heavy as I expect that will slip).

That's a pretty damn good flight rate. They've shown an ability to have a
cadence of every 15 days. This is pretty impressive and does not appear to
have been a surge attempt, but simple operations.


SpaceX has done proof of concept. It appears extrememy promising. But it
hasn't yet proven it will deliver that launch rate.

Just because SpaceX has very good image that gives people confidence it
will deliver doesn't provide proof that it will deliver.

We are still talking about ODDs that SpaceX will deliver being very
high. So if you were betting, you'd bet SpaceX will deliver. But we're
still talking about odds because this is too new to have empirical
evidence.


Granted, we're still at the stage where any one failure still has a
statistically significant impact, but 41 out of 43 is pretty good.
AND that includes 378 flight firings of booster engines (one failure was on
the ground, so I'm not counting that one). And 41 in-flight firings of 2nd
stage engines.

This excludes all testing both on the stand and on flights like grasshopper.
Actually, I just realized my numbers are too low, since I'm forgetting the
refiring of the engines for landing.

So the engine numbers ARE statistically significant.

So they're making their numbers and giving us evidence.


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
https://www.amazon.com/Disaster-Resp...dp/1484221834/

  #28  
Old October 27th 17, 11:52 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,489
Default Were liquid boosters on Shuttle ever realistic?

JF Mezei wrote:

On 2017-10-27 06:27, Jeff Findley wrote:

Again, SpaceX has publicly stated the first reuse of a first stage cost
less than half the cost of building a new one.


Is that PR speak or "auditor" speak? The first reflown stage was not
the first landed stage. Say the first reflown stage uses some engines
that were refurbished from other recovered stages, and their reburb
costs billed to "R&D". Not saying this is what happened, but just one
way to skew numbers for good PR.


You try far too hard to muddy things up. Must they provide you with
an inventory of every ****ing nut, bolt, and rivet to assure you
they're all the same booster?

Customers are already choosing to fly on refurbished first stages
because it gets their payloads in orbit faster


But lets wait until SpaceX actually delivers on a launch rate. Not
doubting it will, but the sample size right now is too low to allow
conclusions.


What are you jabbering about now?

SpaceX has done proof of concept. It appears extrememy promising. But it
hasn't yet proven it will deliver that launch rate.

Just because SpaceX has very good image that gives people confidence it
will deliver doesn't provide proof that it will deliver.

We are still talking about ODDs that SpaceX will deliver being very
high. So if you were betting, you'd bet SpaceX will deliver. But we're
still talking about odds because this is too new to have empirical evidence.


Then you will NEVER have 'empirical evidence' that you will expect
because they could launch 100 in a row successfully and then have 20
in a row fail. It's always 'odds', you nitwit. Life is a bet at long
odds.


--
"We come into the world and take our chances.
Fate is just the weight of circumstances.
That's the way that Lady Luck dances.
Roll the bones...."
-- "Roll The Bones", Rush
  #29  
Old October 28th 17, 03:10 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 1,491
Default Were liquid boosters on Shuttle ever realistic?

In article . com,
says...

On 2017-10-27 06:27, Jeff Findley wrote:

Again, SpaceX has publicly stated the first reuse of a first stage cost
less than half the cost of building a new one.


Is that PR speak or "auditor" speak? The first reflown stage was not
the first landed stage. Say the first reflown stage uses some engines
that were refurbished from other recovered stages, and their reburb
costs billed to "R&D". Not saying this is what happened, but just one
way to skew numbers for good PR.


This was a statement from Shotwell, so I'm personally comfortable that
they tracked the cost to refurbish that particular stage because that's
an important piece of data to track, even during development.

Customers are already choosing to fly on refurbished first stages
because it gets their payloads in orbit faster


But lets wait until SpaceX actually delivers on a launch rate. Not
doubting it will, but the sample size right now is too low to allow
conclusions.


Where the hell have you been? They've launched 15 times so far in 2017
and are on track to launch 19 times total for this year. I'll even
provide a cite:

SpaceX unlocks ?steamroller? achievement as company eyes 19 launches in
2017, ERIC BERGER - 10/27/2017, 9:21 AM

https://arstechnica.com/science/2017...to-double-its-
launch-output-for-any-previous-year/

SpaceX has done proof of concept. It appears extrememy promising. But it
hasn't yet proven it will deliver that launch rate.


Bull****. They're delivering this year with a combination of new and
flight proven first stages.

Just because SpaceX has very good image that gives people confidence it
will deliver doesn't provide proof that it will deliver.

We are still talking about ODDs that SpaceX will deliver being very
high. So if you were betting, you'd bet SpaceX will deliver. But we're
still talking about odds because this is too new to have empirical evidence.


LOL, the empirical evidence is right before your eyes. It's not my
fault that you can't see it.

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.
  #30  
Old October 28th 17, 03:20 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 1,491
Default Were liquid boosters on Shuttle ever realistic?

In article ,
says...

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

"Greg \(Strider\) Moore" wrote:

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


Look at how many Falcon 9 launches failed before they got a success.


You mean 0?
Landing took some tries, but the launches were successful.


I read somewhere in passing that the first three launches failed. I
now think that author confused Falcon 9 with Falcon 1.

Yeah, Falcon 1 definitely had teething problems.

But to be honest, I did have to look it up just to make sure I remembered
the Falcon 9 correctly.

That said, the first 3 flights did all have test payloads, "just in case".


Considering Falcon 1 was their first attempt at an orbital launcher
design, it shouldn't surprise anyone that the failure rate was so high.

There have only been two Falcon 9 "launch" failures (i.e. ignoring all the
landing failures).
The first was the inflight one where I believe a strut collapsed caused
structural damage.
The second was of course the fueling test on the pad.


And considering Falcon 9 was only their second attempt at an orbital
launcher design, I'd say that failure rate is quite good. It's quite
hard to get everything to work right on an orbital launcher.

Atlas V and Delta IV have such a high success rate because they weren't
the first iteration of either design and *a lot* of failure modes were
worked out of the designs via prior versions (and failures). With them,
we're literally talking about launchers with design heritage dating back
to the 1950s.

From Wikipedia:

Atlas:
"The original Atlas missile was designed in the late 1950s and produced
by the Convair Division of General Dynamics,[2] to be used as an
intercontinental ballistic missile (ICBM)."

"The first successful test launch of an SM-65 Atlas missile was on
December 17, 1957.[1] Approximately 350 Atlas missiles were built."

Delta:
"The original Delta rockets used a modified version of the PGM-17 Thor,
the first ballistic missile deployed by the United States Air Force, as
their first stage. The Thor had been designed in the mid-1950s to reach
Moscow from bases in Britain or similar allied nations, and the first
wholly successful Thor launch had occurred in September 1957. "


By comparison, Falcon 1's first flight was March 24, 2006. So, look at
the progress that SpaceX has made in less than 10 years compared to the
progress of Atlas and Delta has made in literally 50 years.

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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