Starship development details

Cool NASA Spaceflight article on Starship.

Following Starship SN6?s hop, SN7.1 prepares to pop
written by Chris Bergin September 6, 2020
https://tinyurl.com/y2hvlcp4

The thing that boggles my mind is how many test vehicles and test
articles are in various stages of assembly and testing right now. It's
even looking like the first Super Booster test article will begin
assembly relatively soon.

This is in stark contrast to the one SLS core stage being tested right
now at the NASA Stennis Space Center. This same stage will be used for
the first orbital test flight of SLS (the uncrewed SLS/Orion EM-1
flight). There is another one (or perhaps two?) flight article(s) that
are currently under construction. Cite from NASA Spaceflight:

Aerojet Rocketdyne getting Shuttle engines ready for SLS Core Stage
Green Run support
written by Philip Sloss September 4, 2020
https://tinyurl.com/yxj9otxv

Jeff
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employer, or any organization that I am a member of.

In article ,
says...

On 2020-09-08 17:33, Jeff Findley wrote:


This is in stark contrast to the one SLS core stage being tested right
now at the NASA Stennis Space Center.

You can't compare SLS against Starship.

Why not? They're both HLVs. NASA even has a contract with SpaceX to
design a lunar landing Starship, which would be part of the Artemis
program (SLS is obviously part of Artemis).

SLS is a binary thing. They go from 0 to final design and once built,
have to do all the debugging at once. But until its is ready, it is just
a dead, delayed project. But one day, it magically becomes 100% ready
for flight without warning.

LOL, yeah. It's using the waterfall development process with very
little flight testing (one flight).

Starship/Super Booster is using the Agile/iterative development approach
with lots of incremental flight testing. Develop the minimum viable
product first and then make it better over time.

But they are in a catch 22 for much: you can't test something until it
flies, but you can't fly until all is tested.

Only because they chose not to invest in cheaper production which would
have enabled more testing (both ground testing and flight testing).
With SLS, the first "production" core stage doubles as both the ground
test article and the only flight test article. That's pathetic, IMHO,
and borderline criminal considering that they're going to put people on
top of the second "production" core stage.

The iterative design for SpaceX is cooler to watch because less opaque.
And you see the progress in the design and build. And because they keep
testing, by the time they build the first final design item, it will be
pretty much all debugged already and be ready to fly.

True.

However, SpaceX started very low for some areas. It had to learn how to
bend steel, then learn how to weld. They started high in other areas
such as landing software.

What they actually did was first focus on lowering production costs and
lowering the time it takes to build them (Elon Musk said this in a
Tweet). Lower, faster, production is precisely what enables them to
test so much.

SLS ignored this approach entirely. As Henry Spencer used to say, they
were using the "performance uber alles" design philosophy. That's what
happens when you use a missile design philosophy to design a launch
vehicle. No one cares much how much it costs or how long it takes to
build an ICBM. It's not like we're trying to maximize their flight
rate! So you end up maximizing payload, minimizing dry mass, and
ignoring cost and schedule.

I reserve judgement on engines because I'd like to see an 8 minute test
firing or flight. So far, the static fires have been very short, many
being just the pre-burners. And SN5's test flight showed flames in
engine compartment.

You're referring to how long Raptors are being fired in flight. We
don't know for sure how long they're being fired at their engine test
facility in McGregor Texas. It's a bit more secluded so there is far
less reporting on that. But there are three different Raptor test
stands the

https://twitter.com/spacex/status/12...077058?lang=en

From above:

@SpaceX, Feb 27 2020
Third Raptor test stand activated at SpaceX's rocket development
facility in McGregor, Texas. In the past year, the Raptor team
has accumulated over 3,200 seconds of testing across 18 engines,
including multiple full-power firings

That's *a lot* of accumulated firing time for only 18 engines, so I am
sure that they've been testing them on the test stands for far longer
than they've been fired during the "hops". The "hops" surely aren't
limited by the engines.

Except for engines, the curent SNs have very little final design on
them. They don't have proper engine mounts, no final landing legs etc.
They are good to test some stuff.

Precisely. Iterative development. You don't need final landing legs to
start initial flight testing. They do have proper engine mounts for the
three center (sea level) engines, which again, is all they need for
initial flight testing. Since Starship won't be going out of the
atmosphere during initial testing, it won't need the three vacuum
engines, so why build "proper engine mounts" on your prototypes for
engines you're not going to mount?

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 ,
says...

On 2020-09-09 17:17, Jeff Findley wrote:

Why not? They're both HLVs. NASA even has a contract with SpaceX to
design a lunar landing Starship, which would be part of the Artemis
program (SLS is obviously part of Artemis).

Because SLS is opaque. Once it will be ready, it will be 100% ready,
until then, it is 0% ready.

Actually, there are a decent amount of press releases from the SLS
program. And they did live-stream the last five segment SRB test. NASA
is opening up a bit more than they have in the past. I think that this
is surely because they see how being open has made SpaceX hugely
popular.

Starship is slowly and visibly increaing its readiness percentage,
although we can't know what the actual percentage is.

Slowly? LOL. SLS started in what, 2011? And that was based off all
the previous development work done for Ares! And I think it's not
likely to fly until 2021 at the earliest. So, more than 10 years of
development with nothing flying. And it's not using any new large
liquid fueled rocket engines (which take on the order of 5-10 years to
develop). So, SLS ought to have been cheap and quick to develop.

Raptor started development in 2009 and is the most advanced liquid
fueled rocket engine in the US utilizing full flow staged combustion.
It's literally the first full flow staged combustion rocket engine that
has flown (Russia developed one, but it never flew).

Development of Starship began around 2012, after SLS started. And
prototypes are already flying. And that's on top of the fact that
Starship is intended to be fully reusable while SLS is completely
expendable. Developing Starship ought to be many times harder than SLS,
by NASA's thinking.

And we also don't know whether Hawthorne designs are far ahead of what
BocaChica builds, or whether Hawthorne waits for results from basic
designs in BocaChica before advancing designs.

It's iterative. All of the test data from Boca Chica feeds right back
into the development work at Hawthorne.

For instance, does Hawthorne already have final designs for engine
mounts, and also designed a temporary simpler one for SN tests, or is it
waiting for various metrics and construction difficulty feedback of the
simpler sdesigns before moving to design the final one?

This isn't an either/or. They're using an aft dome and plumbing for up
to three sea level Raptors on the Starships prototypes built so far.
Surely they have a design for adding the three vacuum Raptors. But
could that design be impacted by the testing of the prototypes? Of
course it could.

Only because they chose not to invest in cheaper production which would
have enabled more testing (both ground testing and flight testing).

It is somewhat ironic because for SLS, they already had so much of the
tech to draw from and experience with those materials/designs. You'd
think they would have had an advantage of building fast and at lower cost.

Not when they're farming the work out to contractors on a cost plus
basis. Coming in cheaper or earlier than planned actually hurts long
term profits in that case. This is because using cost plus, the
contractors generally get a certain percentage of profit out of what
they're paid. So if they're paid more, they make more overall profit.

SpaceX isn't a contractor working on a cost plus contract. Both
commercial cargo and commercial crew are fixed cost. So are all of
their DOD launch contracts. So are all of their commercial launch
contracts. SpaceX is also its own customer (i.e. Starlink). So
lowering launch costs is quite important to SpaceX.

had SpaceX stuck to its original plans, I have to wonder if the
iterative design would have been so "agressive" since making the tooling
to make carbon fibre parts is the time consuming part so one would
assume they would have designed once instead of iterative design.

Not really. You can wind any thickness of tank you want on the same
cylindrical mandrel (the big piece of tooling SpaceX destroyed when it
switched away from carbon fiber). The tooling only changes if you
change the inner diameter of the tank (which they would not have done).

The move to steel certainly has allowed SpaceX to afford to learn how
to handle steel, make mistake and rapidly build very simple beer kegs.
The downside of seeing so many failures is that one never really knows
how "solved" the welding problem is and whether newer beer kegs are now
far from breaking up, or still very close to breaking up with
spectacular fireworks.

One of the next test articles is a tank using their new alloy of
stainless steel, which is a better fit for what they're doing with it.

SLS ignored this approach entirely. As Henry Spencer used to say,
they
were using the "performance uber alles" design philosophy.

In fairness, they were told to use complex designs (SRBs, ET, SSMEs).
SpaceX had the luxury of not only having clean sheet design, but also
being able to change it radically midway by going to steel.

True. Again, they're not a cost plus government contractor and are
therefore not as subject to the whims of Congress. It's Congress that
came up with SLS and told NASA, by law, that they had to use those
suppliers to build SLS. There were no new contracts bid when switching
from Ares to SLS. That was all Congress's doing.

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 Thursday, September 10, 2020 at 11:31:07 PM UTC+2, Jeff Findley wrote:

much snipped


Not when they're farming the work out to contractors on a cost plus
basis. Coming in cheaper or earlier than planned actually hurts long
term profits in that case. This is because using cost plus, the
contractors generally get a certain percentage of profit out of what
they're paid. So if they're paid more, they make more overall profit.

SpaceX isn't a contractor working on a cost plus contract. Both
commercial cargo and commercial crew are fixed cost. So are all of
their DOD launch contracts. So are all of their commercial launch
contracts. SpaceX is also its own customer (i.e. Starlink). So
lowering launch costs is quite important to SpaceX.


This sounds a whole lot like SpaceX is competing in an unfair environment. I.e.: the companies they are competing with are getting special treatment from the purchaser (US gov and military).

Shouldn't there be lobby groups storming the Capitol to protest this?

How about Musk hires some lobbyists and some law firms and sues the government? At this point its not like NASA can punish SpaceX by pulling their funding or revoking their use of facilities at the Cape. NASA needs SpaceX to continue the farce that is ISS.

It's not like Boeing, etc. are not already drowning in government pork with military aircraft contracts.

much snipped

True. Again, they're not a cost plus government contractor and are
therefore not as subject to the whims of Congress. It's Congress that
came up with SLS and told NASA, by law, that they had to use those
suppliers to build SLS. There were no new contracts bid when switching
from Ares to SLS. That was all Congress's doing.

If it was Congress's will then Congress needs to pay for SLS, like out of their personal pockets. This is clearly pork-politics, companies and industries paying Congress to vote to give them more government money.

Folks in the US need to put a stop to this. If I understand the electoral system there about half of the Congressional seats are up for grabs again in the November Elections.

I'm not saying defund NASA, or Boeing, I'm just saying force them to compete on a level playing field. In the end it would be better for NASA, and for Boeing, if they can learn to conduct business like a real company again.


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.


Take care,

REgards
Frank