This episode is sponsored by Squarespace. Getting a rocket safely into orbit is not
easy. Sometimes just getting it off the launch pad
can prove difficult. The challenge is even greater when it's your
very first attempt with a brand new vehicle. Elon Musk recently stated in an interview
that he gives Starship a 50 chance of successfully reaching orbit during its upcoming flight
test. Now Elon does have a tendency to undersell
things at times. Especially when you consider the fact that
he also gave Falcon heavy a 50 chance of success on its Maiden flight. And look how that turned out! Falcon heavy was the first launch I ever experienced
in person. And as we sat on the beach for hours hoping
that it wouldn't get scrubbed, I couldn't help but to wonder about that other 50 percent. Is this just some arbitrary number that Elon
threw out there or do they already know where they expect it to fail? Five years later, we're now just weeks away
from the first ever Starship orbital test flight. But this time around we believe we know exactly
what SpaceX is worried about here. A complete structural failure of the starship's
second stage roughly one minute into flight. This will be a very critical moment for Starship
and after today you'll have a much better understanding of why that is. My name is Zack Golden and welcome to another
CSI Starbase deep dive investigation. Hey everyone! Thanks for joining us. Before we get started, I should probably point
out that this is actually part two of a multi-part series investigating the complete historical
timeline of structural verification testing for the Starship program. In Part 1 we discussed each of the 24 test
articles and Starship prototype vehicles from 2019 through the first half of 2022. We learned about every success, and every
failure that occurred during this time. We place a lot of focus on failures because
a lot of the most important changes to the new iterations in the design of Starship are
a direct result of these events. If you haven't watched that yet, don't worry
because although this deep dive investigation is intended to build upon what we learned
in part one you should be able to follow without having seen it. Today we will be focusing almost entirely
on ship 24 and booster 7. So we can truly get to know these vehicles
inside and out. But first, I realized at the end of part one
that there were some important things about ship 20 and booster 4 that shouldn't have
been left unsaid. For a lot of folks, it was incredibly disappointing
at the time that these two vehicles didn't end up being the first pair to perform an
orbital flight test. But there is something that we should always
remember about ship 20 and booster 4. These two vehicles were the Pathfinders for
a very long list of events. Ship 20 was the first ship with a full thermal
protection system. The first to have six engines mounted onto
it and also the first to fire six hitches at the same time, which was also the first
time the vacuum version of the Raptor engine was ever tested on a vehicle. Booster 4 was the first and only booster to
have 29 engines. The first to receive grid fins, aerocovers
and engine shielding. It was also the first to have a Starship stacked
on top of it. Both of these vehicles performed an extensive
list of tests that help SpaceX verify design changes to the starship, but they were also
used as test subjects for another purpose as well. When it comes to certifying the ground support
equipment, there's only so much you can do without having an actual vehicle to test it
on. So for this reason, whether it was going to
fly or not SpaceX needed Booster 4 in order to test fit the hold down clamps on the launch
mount for the first time. They also used it to test fit the booster
quick disconnect and later the 20 Raptor QD's which are used to start up the outer 20 Raptor
engines. They used it to test the gas distribution
system for the orbital tank farm, including the liquid oxygen and methane pre-pressurization
system and loading of the composite overwrapped pressure vessels. They tested propellant loading and the detanking
process for the first time using booster 4 as well. That one in particular could be a pretty dirty
process considering that the booster is basically being used as a massive basket strainer for
cleaning out all of the residual foreign objects and debris left over in the cryo-pipe system
after construction is completed. Booster 4 was also used to test the igniter
system which delivers high pressure oxygen and methane to the igniters for the outer
20 Raptor engines. Moving back to Ship 20. It was the first vehicle to be lifted by the
Chopsticks, allowing SpaceX to verify the functionality of that design and dial in its
performance during stacking operations Ship 20 was the Pathfinder for testing out the
Starship GSE arm and quick disconnect umbilical. And finally it was used to test out the propellant
loading system of the orbital launch integration Tower just like the booster did for the launch
mount. There are tons of others that I have left
out, but I think you get the point. Ship 20 and Booster 4 were straight up workhorses
even though they never reached the final milestone. So now that we have the obituary for Ship
20 and Booster 4 out of the way, let's move on to discuss the current generation of Starship
because there is a lot that we have to cover. Once again we will need the assistance of
Special Agent Jax from The Ring Watchers who we uploaded into the CSI Starbase artificial
intelligence system a few weeks ago. Glad to have you with us Jax... uhhh why,
why are you so tiny? Well some of the folks in the comments from
part one said they didn't like my little Avatar. Yeah I saw that. I mean it is kind of creepy but don't worry
I got a firmware update for you although since you're a bot you probably could have done
that yourself right?Anyways I also noticed in the comments that a lot of folks feel like
the ring Watchers need to create their own website to store all the information that
we're covering. It'll probably end up being one of the most
detailed wikis available for Starship! Sounds pretty time consuming. Well it doesn't have to be thanks to Squarespace
who's the sponsor of today's investigation! Uh what is Squarespace check this out Squarespace
is a website for building websites it's like website Inception within minutes you can get
started building out your site using their wide variety of styles in their award-winning
template library that can help give your website its own unique Personal Touch you can even
create a digital Archive of photos and videos thanks to their unlimited storage space which
makes it really ideal for photographers or anyone who needs to create an online portfolio
to Showcase their work. Squarespace even allows for easy management
of premium content, donations, and merchandise. I mean look at this! You can design your own merch within the built-in
editor or import your existing designs from external sources. Look how quickly I created these CSI Starbase
hats. I'm assuming this means you'll be making these
available soon right? I mean at this point I really have no excuse
anymore. I didn't realize how easy it is to create
these hats when I started and now I'm pretty upset that I didn't do this earlier. Anyways if you want to try it out for yourself
head over to squarespace.com/csistarbase and get 10% off your first website or domain. You can find the link to that in the description. So, before we can explain why SpaceX is worried
about a catastrophic failure of the vehicle during Max Q, we need to understand how we
got here in the first place. So let's get to know ship 24 and booster 7
a little better by reviewing all the important events that have occurred since flight Readiness
testing began in March of last year. It's been an incredibly long journey to get
them ready for this first orbital flight test and there have been many complications along
the way that could have forced SpaceX to scrap both of these vehicles. As we go through this keep in mind that Starship
is still relatively early in the development phase. Spacex's iterative design approach involves
constantly testing and improving their Rockets through multiple design iterations. While this approach has many benefits, such
as allowing for Rapid development and reducing costs it can result in problems if not managed
properly. One potential problem with this approach is
that it may lead to a lack of thorough testing. This problem gets amplified if design and
Manufacturing teams start to outpace the testing process, which I think is exactly what's happening
here. I don't think this is due to a lack of foresight
or competent management however, because SpaceX has a ridiculously talented team of Engineers
leading this project. In this case, the early retirement of Ship
20 and Booster 4 forced them to move up the timeline on the next generation of Starship
much earlier than planned and everything we are going to discuss today is a result of
that unfortunate situation. Alright take it away Jax. We'll start off with the one and only booster
7. Love it or hate it, you can't deny that booster
7 has been through some weird stuff. It was fully stacked on March 10th of 2022
and rolled out to the pad at the end of that month. It conducted a pretty uneventful cryogenic
proof test on the orbital launch Mount which was the first time a super heavy booster had
ever been fully filled with cryo fluids. This is when SpaceX decided that it was time
for booster 7 to go through some thrust Ram tests because B7 was in this new generation
of vehicles it was the first to use the new Raptor 2 engines and the first to sport 33
of them rather than 29. This meant a new thrust Puck and a wider hole
in the dome for it. If we pull up Booster 5's 9 engine thrust
Puck we can compare it to Booster 7's right here. If you aren't sure what a Thrust Puck is,
we discussed that a bit deeper in part one of this investigation but essentially it's
the plate that takes the forces of the inner cluster of gimbaling engines on both the booster
and the ship. But back to these booster pucks, not only
do they have very different methods of Machining but they also vary in size. The nine engine Puck is about 4.8 meters across
whereas the new 13 engine Puck is about 5.6 meters across. This also meant that the can crusher test
stand had to be tested in a completely new configuration from how we saw it used in part
one of this deep dive investigation. As you can see on the concrete pad in the
center of the structure 13 thrust ramps were arranged to test the center gimbaling engines. Without placing the cap on top of the booster
and using 140 meters of rope to pull down on the top, there was no way that SpaceX was
going to be able to perform max-q testing on the vehicle. So it looks like this test was primarily for
testing the thrust bearing structure of the booster. So SpaceX lifted booster 7 off from the launch
Mount and carried it over to the can crusher and attached the 13 hydraulic Pistons to the
booster Center engine mounts. They eventually conducted a test using these
thrust ramps on April 14th of 2022. And it looks like B7 passed with flying colours. SpaceX started detanking Booster 7 with the
intention of sending it back to the highbay for installation of its 33 Raptor engines. Unfortunately the next day we found out that
this test did not go as smoothly as we initially believed after SpaceX Crews opened the hatch
to the liquid oxygen tank of the booster and began inspecting the interior with a long
fiber optic camera. I'm sure that many of you watching this video
know by now what I'm referring to. But what exactly happened during this test
Zack? Oddly enough this is actually something I
covered in my first ever YouTube episode on April 29th of 2022. this was a test when booster 7's downcomer
failed during the detanking procedure. As Jax mentioned, everything was going well
during the first part of the test. But as they say, it's not over until it's
over. So after the thrust Ram test was complete,
SpaceX began to drain the fluids from the liquid methane and oxygen tanks. When the detank was almost complete they started
to depressurize both tanks which is a common thing to see near the end of the process. The methane tank was vented in short bursts
to release the pressure but the liquid oxygen tank was vented continuously for nearly 20
minutes non-stop. When it reached the point where it seemed
like there was barely anything left in the LOX tank, SpaceX opened a single vent on the
methane tank for a final time which only lasted for about 10 seconds. Five seconds after it stopped.... [LOUD BANG] Labpadre's Rover 2 camera picked up the sound
of the internal collapse of the downcomer inside of the header tank and the effect of
that violent action was visible on the outside of the booster as you could see a line of
frost falling off of the LOX section. Using this animation from 3D forensics agent
Chameleon Circuit we can see what this downcomer looks like as it's passing through the LOX
header tank. Keep in mind this part of speculation, but
what we believe happened here is that during the final deep press event of the methane
tank the downcomer was completely empty or close to it. The LOX header tank was more than likely still
filled with fluid or it was at a significantly higher pressure than the void space on the
inside of the downcomer. When the vent on the methane tank opened up
and dropped the pressure even further, the pressure differential between the header tank
and downcomer became too great and caused the downcomer to collapse in on itself like
this. It's a really good thing that this test was
using liquid nitrogen in the methane tank because had this happen under different circumstances
it could have resulted in a rather large explosion even though the tanks were near empty. This procedural failure ended up functioning
as an unintentional structural verification test for the methane downcomer tube. SpaceX was able to remove it and install another
one piece by piece, but this time we believe they welded extra hoop stiffeners around the
transfer tube. We have seen the methane transfer tube on
a future boosters received significant reinforcement upgrades. Not only did they increase the number of ribs
on the tube, but they also stopped using singular strip of Steel that could easily crinkle up
like a bag of Ruffles. In the newer design they now have thicker
ribbing and it appears to consist of two discs welded together, which is only noticeable
because of the weld marks that join them together. On top of this there is a flat strip that
forms a two-sided trough which might also function as a slosh baffle to some degree. Returning to booster 7, the downcomer replacement
took just under a month to complete and on May 11th of 2022 it performed another cryo
test to verify that the repairs were acceptable. So once booster 7 had completed this re-verification
cryo-test and proved that the newly replaced downcomers section was structurally verified
it rolled back to the MegaBay once again to be prepared for static fires. During this downtime SpaceX rolled out their
brand new starship prototypes that they had produced like booster 7 ship 24 Sports numerous
design changes compared to its predecessors many of which changed the structure of the
vehicle first off SpaceX heavily redesigned the aft section of the Starship. With the switch to Raptor 2, the Dome was
modified with the brand new mounts for these engines. However it's important to note that the general
design of the thrust pack itself is still similar to sn15s which we discussed in Part
1. There are a lot of other changes but we'll
discuss those a bit more when they become relevant. So on May 26th, 2022 SpaceX rolled it out
to the orbital launch site cryostation by the tank farm. If you aren't aware that Cryo Station is a
location where the ship can conduct proof tests right on its transport stand. The reason the ship was tested here was because
SpaceX was still in the process of upgrading Test Stand A to support the new changes to
the quick disconnect panel on this generation of Starship. When it arrived, SpaceX set up for the first
pneumatic proof test or ambient proof test using gaseous nitrogen to bring it up to pressure. How did that go Zack? Well this is another topic I've covered in
the past episode so I'll make this a quick review. Unlike the downcomer collapse on booster 7
where we didn't find out about the problem until the following day, it didn't take much
to recognize that there was an issue the moment this occurred. You could very clearly hear the sound of the
pop which was followed by about 20 thermal protection tiles falling off of the ship. in contrast with a lot of the events that
we covered in part one of this investigation, Elon hasn't been as forthcoming with details
about incidents like this. So we're forced to do the detective work ourselves. Thankfully SpaceX decided to repair the damage
at the launch site which is the only reason we know what occurred during this test. So let's take a look at the inside of the
nose cone so we can see what's going on here. At the top of the nose cone there are two
header tanks. One for liquid oxygen and the other for liquid
methane. Each of these tanks require a pipe for filling
and draining liquids and also for tank pressurization. The ones for pressurizing the tank are the
two smaller lines on the left. In ship 24 these were originally designed
to be straight pipe sections going all the way from the top of the forward Dome, to the
header tanks above. Unfortunately this design didn't account for
the effects of large temperature swings inside of the stainless steel piping. So as SpaceX went to pressurize the header
tanks there was likely a large temperature increase causing significant thermal expansion
in the pipes. This thermal expansion caused the pipe to
buckle which is what created the loud pop we heard. A few days later Starship gazer live streamed
as SpaceX Engineers Removed the damaged section of pipe allowing us to see the bent section
as it was extracted from the payload Bay. It was replaced with a new section of pipe
containing u-shaped expansion loops which would allow it to have more freedom to expand
and contract. This was a great thing to figure out on the
ground instead of during flight, especially since any issue involving the header tank
is going to occur when the vehicle is coming in to perform its Landing maneuver. So once this repair was completed, SpaceX
was finally able to perform its first cryo test of Ship 24 on June 2nd of 2022. With the first cryo proof test successfully
out of the way, and upgrades to Pad A's new quick disconnect now completed, ship 24 moved
to suborbital Pad A. Once there, it conducted two additional cryogenic proofing's using
the six thrust rams underneath of the vehicle like ship 20 used in 2021. On ship 24's aft dome, the stiffening structures
around the Raptor vacuum mounts had been redesigned which is why we saw the thrust rams get used
again. On ship 20's generation, these were mounted
on the exterior face of the Dome. Ship 24 plus has them on the interior. The first test on Pad A was on June 6th followed
by another the next day. From here with the cryoproofings out of the
way ship 24 was dismounted from the suborbital pad and returned to the production site to
receive its six Raptor engines, and other finishing Touches. But now it was time to start doing some quick
testing because ship 24 and booster 7 were both already receiving engines and there still
hadn't been any test tanks to verify the upgraded designs. So SpaceX constructed booster 7.1 to verify
the design of booster 7's aft section. B 7.1 is a test article made out of a 33 engine
aft section designed to be used on the can crusher in the 13 engine configuration. It's sort of the same concept as B 2.1's test
in 2021 where it was testing the Integrity of Booster 4's generation aft section as we
talked about at the end of part 1. This test tank featured long stringers on
the bottom of the AFT section which was also something that they added to every booster
that came after the failure of B 2.1. So part of the goal was to not have the AFT
section fail in the same ways that it did in the previous test. The last thing to mention about B 7.1 is that
it had stringers added on the forward dome in order to allow the can Crasher cap to be
mounted on top of it. But this wasn't an actual booster forward
Dome being tested this time. It was just a leftover Starship forward Dome
they had lying around. This is how we know they were only focused
on the thrust bearing structures of the booster with this test article. HOLD ON Jax I'm going to cut in here for a
second because I think it's probably a good idea that we briefly explain what a Thrust
bearing structure means in this situation. So let's start off with the center 13 engines. The largest of the thrust bearing structures
on the booster in terms of overall surface area is the aft dome. While the center 13 engines are firing there
will be a force pressing upwards on the thrust puck. That Force must be transferred from the thrust
Puck to the AFT Dome and then to the outer walls of the liquid oxygen tank. This happens along the point where the AFT
Dome is welded. This is part of the reason why it's important
to have these extra stringers around the wild line. So next we can consider the outer 20 Raptor
boost engines. This is pretty straightforward literally because
the thrust is directly transferred through the aft skirt to the walls of the LOX tank
section. That's why the additional stringers on the
last ring section are extremely important as well. Anyways B 7.1 first rolled out to the pad
on June 16 2022 and was set up on the can Crasher stand three days later one interesting
thing to note is that with B 7.1 the thrust Puck did have 13 engine mounts but it was
not the same design as booster 7s. SpaceX had already verified b7s during its
own cryoproof testing so they decided to put booster 9's revised thrust Puck on 7.1 which
meant that in the future booster 9 would not have to go on the can crusher. This was pretty cool as it would ideally speed
up the future testing campaign. There were some important changes with how
the can crusher was configured for this test that I will allow Zack to explain here. Allow? Anyways this is honestly one of the most peculiar
configurations that we have seen the can Crusher arranged in thus far. What was unique about this test that we hadn't
seen previously is that SpaceX also decided to add additional Pistons to test the mounting
points for three of the outer 20 engines. This was difficult to notice if not for the
missing catwalk Platforms in the center we probably wouldn't have caught it. But you can see that tucked way back there
in between the hold down clamps are two pistons. After we noticed this, we were able to go
back and look through the footage from NASASpaceFlight when the can crusher was rolled out. You can see them sandwiched between the columns
for the 20 booster clamps. Looking at it again a few days later. After it arrived at the launch complex we
can see that there was an additional thrust Ram added before Booster 7.1 was placed on
top. The reason I find this interesting, is because
it means that SpaceX decided to use the results from a localized test of just three engine
positions instead of performing this test on all 20 to verify the structural Integrity
for the entire thrust bearing structure of the vehicle. Now this isn't to say there's anything wrong
with that. It's just an interesting observation. B7.1 started off its four cryogenic tests
on the can crusher on June 28th this test was one of the more interesting ones to watch
because we were able to clearly see the Pistons on the can crusher being pulled down repeatedly. Each time the Pistons pull down is considered
a cycle test. This is similar to the testing that Zack mentioned
was performed on Falcon 9 back in Part 1. Falcon 9 performed more than 150 cycle tests
but unfortunately we weren't able to determine how many were conducted on the B7.1 test tank. This structural test was followed by three
additional ones on July 19th, 21st, and 27th. During the July 27th test on the NASA space
flight live stream, the can pressure actually partially crushed B 7.1. The audio you're hearing from this test is
from Andrew Keating from cosmic perspective and it really gives you a sense of how much
force is being applied when the stringers buckled. This was just the top of the tank which is
a glorified testing interface. The bottom was the main area of focus for
this test so the top was really just something to press down on. But this was still pretty rough, so B 7.1
returned the production site to be repaired. In the meantime SpaceX got to work on the
real Tooster 7 which had returned to the launch site about a month before and was preparing
for its first spin Prime tests. The goal here was to quickly move to static
fire testing now that thrust Puck and aft section had been structurally verified. Booster 7 now had all 33 Raptor 2 engines
its grid fins and a variety of other new pieces. Once on the pad booster 7 performed an igniter
test for the first time with the Raptor 2 engines. July 11 2022 the day of the first 33 inch
in spin Prime when all 33 engines spun up the mixture of methane and oxygen beneath
the olm decided to detonate. Zack put out an episode after this happened
which was a deep dive explanation into what caused this event, so I recommend checking
that out after this video if you happen to be new to the channel. Booster 7 then rolled back to the Megabay
for repairs. Ship 24 was the next to return to the launch
site looking nice with its new paint job. It was mounted on suborbital pad B and conducted
seven spin primes in various configurations. On August 9th Ship 24 conducted a two-engine
static fire using a center engine and a vacuum engine Booster 7 was also back out of the pad by
this point in time, now only sporting the 20 outer Raptor boost engines. Two spin primes were conducted on August 8th
and the next day Booster 7 performed the very first single engine static fire on the Orbital
Launch Mount. Another static fire happened 2 days later,
but this time it was for a duration of 20 seconds to test after 7's autogenous pressurization
system. Autogenous pressurization, that's a term we
hear thrown around a lot. But what exactly is it? Well I've explained this on many past episodes
so this time I'll talk about it from a conceptual point of view instead of going in depth on
how it's accomplished. Autogenous pressurization is a method of pressurizing
a spacecraft's repellent tank using the propellants themselves. In this method the liquid repellents are vaporized
inside of the engine and a small amount of the resulting gas is used to build up pressure
in the tank. The pressure generated by the vaporization
of the propellant is used to force the remaining propellant out of the tank and into the engine. It's important to note that as the engines
are throttled up, the volume up propellants consumed will increase and therefore the amount
of gas being diverted back to the tanks will have to increase as well. As more engines are firing, the system must
be dialed in to balance the pressure inside of the tank to prevent them from exceeding
the max pressure rating or collapsing the tank once it falls below its minimum operating
pressure. So this test would have to be conducted again
in the future using more engines to make sure that it's performing as expected. Well after this static fire Booster 7 returned
to the High Bay to receive the center 13 engines. When it returned, it conducted a couple more
spin primes and attempted a three engine static fire. However it seems that during this test only
two engines actually ignited, and one auto aborted during the spin up. Either way it looked like a good burn. After this, SpaceX conducted the first 33-inch
in spin time since the anomaly that occurred back in July. Taking a step away from booster 7 momentarily,
B7.1's repairs had finally been completed and it was back out at the pad. During B7.1's stay in the Midbay SpaceX had
cut off the damaged area around the top and added a new interface piece for the Can Crasher
cap. At the pad it conducted two more structural
tests and you can even see the outer 20 Pistons doing their job once again pulling down in
the tank. And it looks like B7.1 successfully passed
testing. Following this test we saw B7.1 and the e-dome
test tank - which we'll talk about in just a little bit - move over to the new Massey's
testing site. Massey's is an old gun range that SpaceX now
owns and has converted to a cryogenic testing site. Today cryogenic testing can be conducted on
test tanks and entire ships. In the future we expect that boosters will
be able to make the journey over to Masseys as well. Stepping away from Massey's ship 24 was undergoing
some testing at this point in time and conducted a six engine static fire. Some unexpected work followed this, but in
the meantime we can talk about ship 24's counterpart Booster 7. Back on the orbital launch mount, it conducted
several spin primes over a span of seven days. Yo I hate to interrupt but do you think we
can skip all these spin Prime tests? no
damn all right then Spin Prime Tests are important for verifying
that all of your engines are functioning as expected before firing them. These tests essentially take the engine all
the way up to the moment of ignition except with the igniters disabled. It's essentially an aborted static fire in
some ways. By performing these tests SpaceX games a lot
of data that allows them to know for certain that they won't expected failures that could
cause an explosion on one of these raptor engines on Startup. So this series of tests were followed by a
7 engine static fire on September 19th. SpaceX was cautiously working their way up
to static fires with higher engine counts. After this, booster 7 once again rolled back
to the production site for what SpaceX referred to as "robustness upgrades". When it returned, Ship 24 and Booster 7 were
fully stacked on the orbital launch mount for the very first time. Which was pretty exciting, there's no doubt
that this stack looked much cleaner overall compared to Ship 20 and Booster 4. Together they conducted multiple cryogenic
propellant loading tests. Likely the single species propellant loading
test that this slide from NASA was referring to. Around this time over at the Massey's testing
site, the e-dome test tank was getting set up. Timeout. Why do they call this an e-dome? Is there something significant about it that
warrants the break from the typical test tank nomenclature? Well this is actually how it was labeled by
SpaceX. We've been assuming that the E probably stands
for elliptical or ellipsoidal Dome. This test tank uses brand new flatter domes
made out of stretch formed panels and it was stacked all the way back on June 3rd of 2022. So what is the reason that they would want
to switch to this type of flatter Dome design? Well to answer that, let's look at the current
dome design that SpaceX is using on Starship. These domes are made out of a total of 38
pieces that all get welded together, these are also believed to still be stamped panels
like Elon described a few years ago. These newer domes are only made of 19. The long panels that make up the dome are
also now stretch-formed. Here is an example of how some stretch formed
panes are manufactured. This is a change that was also implemented
on the nosecones of the Ships. These changes allow production of the domes
to be faster, and it also reduces the number of welds that make the dome, reducing the
chances of introducing weak points. If you shift the domes just right, you should
be able to keep the same propellant volume, while also slightly increasing your usable
payload volume. Alternatively, you should be able to slightly
increase the amount of propellant volume in the tanks while keeping a similar usable payload
volume. Overall, these domes are easier to make, simpler,
and are a much more efficient design altogether. Edom rolled out to the launch site after it
was stacked and it really didn't do much during its stay. It appears that SpaceX didn't want to interrupt
operations of the launch site for testing that didn't directly relate to Ship 24 and
booster 7. In August it moved back to the Sanchez Site
and it then went out to the Masseys testing facility. We didn't even know that testing had begun,
but during a flyover, Mauricio for RGV Aerial Photography saw EDOME all frosty, so he contacted
Labpadre and had him swing Sapphire Cam over just in time to catch this. The dome cap in the center of the forward
dome had been blown off, not a great result. A later flyover showed that whatever remained
in the opening had been cut off. Over the next few weeks, crews repaired the
test tank and replaced the dome cap. Sometime between October 20th and 29th, EDOME
was tested again, this time ending in what would have been a very large pop. In this aerial photo, we can see that the
entire lower dome shot off of the tank, which goes to show that this must have been under
a considerable amount of pressure. We haven't heard anything official about this
test, but we know that these domes are already being implemented as Booster common domes
with B10 and onwards, so it probably went well enough. SpaceX's next Starship made it out to the
launch site at this point, and Ship 25 was ready to conduct some cryo testing on Pad
A with the thrust rams. So, on November 1st, it conducted its first
cryogenic pressure test, followed by a second on November 2nd, and a 3rd cryo on November
7th. Ship 25 then returned to the production site
for engine installation, but this whole process didn't go exactly how we expected. We'll discuss that in a little bit. Back to B7, with whatever the "robustness
upgrades" were having been completed, it returned to the pad and conducted a spin prime. This was the first time SpaceX used the new
FIREX and detonation suppression system that would now be active during all engine tests
from here on. Zack has a video on that as well if you would
like to learn more about it. This spin prime was followed by a static fire
of 14 Raptor engines on November 14th. About 2 weeks later, on the 29th of November,
it conducted an 11 engine static fire with a full LOX tank, once again testing out the
autogenous pressurization system. This static fire lasted for about 13 seconds. An interesting thing about this test is that
you could actually see the gaseous oxygen being purged from the LOX tank. I think this may be a sign that the autogen
system was actually over performing during this test, causing the booster to automatically
release the excess pressure. Great observation! Following this test, as seems to be typical
for Booster 7, it went back to the Production Site for finishing work ahead of its launch
attempt. We're now going to talk about Ship 24 for
a bit. In the latter half of 2022, SpaceX appeared
to run into multiple issues with the vehicle. Most notably, the Payload Bay and the aft
section. Both of these, if left unchecked, may have
resulted in a mission failure. Let's check it out. After Ship 24's 6 engine static fire on September
8th, 2022, SpaceX got to work setting up scaffolding directly beneath the sliding payload bay door. Ship 24 is... well, was... equipped with a
Starlink version 2 deployment system. An internal racking system allowed 2 stacks
of Starlinks to be loaded side by side. There is a built in lifting mechanism that
grabs onto the newly loaded satellites and then lifts the entire rack so another pair
can be loaded underneath, like a palette loader. The Starlinks are loaded onto the ship using
this white box which is lifted using the Highbay bridge crane and gets mated with the ship
so that the Starlink V2 sats can be transferred from the loader, to the ship with relative
ease. This is a convenient way for SpaceX to avoid
constructing a large payload integration facility this early in the development process even
though they have stated that there will be a facility constructed for this purpose in
the future. Once in orbit, the Starship will deploy its
payload by shooting them out of the small door like a PEZ candy dispenser. But, Ship 24 didn't get to keep this system
for long. With this new scaffolding set up beneath the
door, SpaceX got to work. What exactly did they do here Zack? By now, a lot of you are probably already
aware that the payload bay on Ship 24 and Ship 25 have both been welded shut and have
had covers installed over them. We haven't received any official explanation
for why this was done, so we have to examine the available evidence as closely as possible
to try to come to these conclusions ourselves. So let's take a step back and start by examining
the basics of the overall design of this version of the Starship payload section. The first step in creating this payload bay
is to form a 5 ring barrel and install all of the internal Stringers. On ship 24 there are 88 stringers and on ship
25 they increased this to 94. You can see these stringers from the outside
of the ship thanks to the weld markings on the skin of the vehicle. You will notice that below the weld line for
the forward dome of the ship, there are no stringers. The reason for this is because both the liquid
methane and liquid oxygen tanks of the ship get most of their strength as a result of
being pressurized up to somewhere between 6 and 8 bar. This is equivalent to a range of roughly 87
to 116psi. Pressurizing the propellant tanks to this
level will have a stiffening effect on the tank walls and the entire rocket structure. This is because the pressure inside the tank
exerts a force outwards against the walls, which helps resist deformation. Essentially, by counteracting external stresses
on the tank, it becomes more resistant to buckling. The payload section on the other hand, will
be unpressurized while the door is open and when its closed should only hold about 1 or
2 bar of pressure during flight operations. This is why the stringers are necessary in
this area in order to make up for the reduction in wall strength due to it being a non-pressurized
space. I believe that these stringers primarily increase
strength in the axial direction. These forces will be the greatest during Max
Q but they will also come into play during re-entry After the stringers are installed, additional
hoop stiffeners are added as well. These hoop stiffeners have teeth that allow
them to slot between each of the stringers, and contact the inner wall of the ring section. They are welded both to the stringers, and
the inner wall which makes it so you can easily see them from the outside. Any time we see these dotted weld marks in-between
the vertical lines for the stringers, we know there are hoop stiffeners present. These hoop stiffeners compliment the stringers,
by increasing the strength of the vehicle in the radial direction. I think these forces come into play primarily
during the re-entry phase, but I'm definitely not an expert in aerospace structures, so
take everything I'm saying on that subject with a pinch of salt. Anyways, with the internal reinforcements
installed, the next step Is to cut an opening into the barrel section of the ship in order
to create the actual doorway. I think that the height of this door makes
it appear like it wouldn't be that big of a deal when it comes to how it affects the
overall structural integrity. But, when you take a moment to consider the
length of the opening, it's really quite staggering. This opening is just over 7.2 meters wide,
which is a lot considering the ring sections of the starship have a diameter of 9 meters. If you look at a cross sectional view from
above you can see that the angle made by the opening is about 108 degrees which represents
nearly 30 percent of the total circumference. Because this doorway is located at the bottom
of the payload section, it means that it must support everything above it. This includes more than 80% of the nose cone
structure, both forward flaps, and all of the COPV's that are mounted in the top of
the nose cone. This also includes the header tanks which
will add several tons of additional mass to the top of the structure once they are filled
with liquid propellants. Oh, there are also a few thousand TPS tiles
as well. Not only must it support all of that weight,
but it will also be required to withstand the dynamic drag forces that will be exerted
on it during the Max Q phase of flight. Without the gigantic hole in the barrel section,
the static and dynamic forces would be relatively uniform throughout the entire 5 ring stack,
increasing proportionally as you move down towards the forward dome of the methane tank. These forces increase during flight as the
vehicle approaches the point of maximum aerodynamic pressure. Now let's take a look at how that changes
once you introduce the doorway. Keep in mind that this is just a conceptual
representation and isn't based on actual simulation data but you can see that with this large
section of material removed, the path of those forces will now have to be redirected around
the opening. This will create an area of significantly
increased stress concentration around the left and right edges of the door way. Something has to be done to compensate for
the additional stress that will be experienced in these areas. Now, if this was an observation window that
we were talking about here, this problem would be solved by placing structural supports over
or inside of the opening similar to what we see in conceptual renders of the Starship. These supports could be made as large as necessary
to accomplish the job. Not only this, but the windows themselves
would ideally be integrated into the outer walls of the ship so that they will become
load bearing structures that contribute to the strength of the hull. Unfortunately the sliding door for the current
version of the Starship Payload variant, is not integrated into the walls but is instead,
mounted on two rails above the doorway. I wish I could show you what these look like,
but we have no idea because SpaceX is super sneaky when they install these doors. But what we do know, is that this door is
a completely separate structure that is essentially being suspended from inner walls of the ring
section. So what did SpaceX Engineers do in order to
make up for the fact that 30% of the structural supports holding up the payload section had
essentially been eliminated? Well after Ship 24 was fully stacked in the
Highbay, they installed 3 sets of long stringers on either side of the door which extend from
about 2.5 meters above the opening to 5 meters below it. Initially, they believed that this would be
enough to reinforce this major weak spot that was created by designing the door in this
way. But shortly after Ship 24's six engine static
fire attempt, they decided that this was simply not going to work. On the morning of September 15th SpaceX workers
slipped a thin sheet of steel underneath the vertical stringers at the edges of the doorway. Over the following eight days they added an
equally thin frame around the top and bottom of the doorway as well. This strip of steel creates a four inch, or
10 centimeter overlap around the opening which should help increase the stiffness of the
frame. It might not look like much, but it's important
to remember that the Starship is constructed of 4 mm stainless steel, so this little strip
is doubling that so it's now 8 mm. After this frame was welded around its entire
perimeter it was finally time to install the cover to completely seal the opening. Before they did this, several holes were drilled
through the sliding door to allow the void space between the door and the cover, to equalize
to the same pressure as the rest of the nose cone. After the cover was lifted into place and
properly positioned, they temporarily secured it using small tack welds spaced out along
the perimeter. When we zoom in you can see that there are
small rectangular holes along the entire length of the stainless steel cover. Each of these received two spot welds on the
top and bottom edges of the cutout Once it was supported enough by the tack welds
they were able to remove the lifting jig and then complete the final weld around the entire
perimeter of the giant metal cover and also around the perimeter of all 220 cutouts. So yeah, this was a lot of hand welding that
had to be performed over the span of about a week. A few weeks later, we also noticed some new
weld marks appear above the door cover which is a sign that some additional reinforcements
were added to the interior of the ship. These were most likely some sort of bracket
to hold the sliding door in place to prevent it from moving. On ship 25 they they took a similar approach
when sealing the door. SpaceX may have welded the door to the edges
of the cutout for the opening but it's hard to be certain. This would effectively make it so the door
is now actually contributing to the structural integrity of the payload section by bridging
the gap and creating a new path for axial forces to pass through. But, like I said, we have no proof of this. Anyways, after ship 25's door was welded they
removed the small stringer supports that were initially on either side of the door and then
installed a similar, but larger weld doubler frame to go around the perimeter of the opening. These are also referred to as super stringers
by SpaceX and that's likely because they essentially serve the same purpose. You can see there is additional material used
in the high stress zones that we mentioned early So when it's all said and done there are now
4 layers of steel sheets that overlap around the frame of the opening which means there
is nearly 16 millimeters of structural framing now in those areas instead of 4. There is 8 millimeters of material in the
center not including the void space between the two sheets or the structural supports
are on the backside of the door. So, Ship 24 and 25 now had their doors sealed
shut. But the question remained for many: why do
this? We definitely don't know for certain, but
there seems to be a few possibilities. This is what we can say with a fair amount
of confidence: This now seemed to be a design flaw. Both Ship 24 and 25 had their doors sealed. With Ship 25, this seemed totally unprompted. It had only completed basic cryogenic tests,
nothing that would have caused damage to the system unless something occured during transportation
So, what could have gone wrong? There was a LOT of internal work on these
vehicles during the sealing period, and it's possible that some measures were taken to
reinforce the opening or somehow bridge the gap. It's impossible to say, but it's something
to think about. SpaceX had not conducted any structural verification
testing on the PEZ system at this point in time either, so it seems like they either
conducted computer simulations or something happened to the real vehicles themselves. SpaceX sealed Ship 24's door right after the
6 engine static fire, which we know was... violent. It's possible that the vibrations from the
static fire could have caused some damage to the dispenser system as a result of an
inherent design issue with it, but there's no way to really prove that. If computer simulations found that the PEZ
dispenser was unstable, it would be hard for us to know that as well. But, sometimes to find what the issue was,
we can look at the solution, so let's look at what SpaceX did with the PEZ dispenser
after Ship 24 and 25. This oddly takes us to one of the first payload
bay pathfinders which was constructed before Ship 24's. It was originally designed with a door that
would have operated like this depiction from Ryan Hansen Space. This design used a large door that took up
the entire 5 ring payload barrel, but there were some issues with it. After it sat outside for quite some time,
it became clear that this design wasn't exactly stable, and you can see that the top portion
above the door had started... sagging and was being held up with chains. Anyways, on the opposite side of its large
door, SpaceX cut out a PEZ dispenser hole for some more pathfinding. On the right-hand side of this barrel, we
can zoom in really closely to see a lot of doubler plates stacked on top of each other. So they were pathfinding reinforcements, and
we knew that a fix for the PEZ dispenser system was on the horizon. Now it seems weird that they gave it 2 smaller
door cutouts, but it eventually became clear that this barrel was so structurally compromised
with all of the holes in it, that crews had to cut around the internal reinforcements. Many people have been wondering if it would
be worth doing 2 smaller doors for deploying Starlink satellites, but the way I see it
is that you have to do a big door eventually, so even ignoring any fitment issues that may
arise from rotating the satellites 90 degrees, it might be worthwhile to figure out how to
do a wide cutout sooner rather than later. But regardless of that, with all of these
extra doubler plates, we were waiting on these changes to be implemented. Ship 27 and onwards implemented these changes,
and looking at Ship 28's, we can see that these doubler plates had been added on each
side of the door, adding up to a total thickness of about 16mm of steel in those areas, assuming
these are 4mm plates. Additional doublers continued around the perimeter
of the door, but it's only 1 layer. Another addition was 9 remove before flight
locking plates that hold the door in place. Now this could be as simple as a safety feature,
to make sure the door stays closed on the ground, but maybe it's to keep the door secured
during ground testing. Either way, we know that SpaceX had suddenly
decided to heavily reinforce the opening in the side of the Ship, which may suggest that
Ship 24 and 25 had a structurally compromised opening. But it's not for certain. If this was the case, during the ascent or
reentry portions of flight, the doorway could have tried to deform and even begin to fold. If this happened, the vehicle would likely
be destroyed pretty quickly. The aerodynamic forces would likely try to
tear the vehicle apart, but we also may see the Methane and Oxygen pipes that run up the
payload bay get damaged. If this happened and they possibly ruptured,
the pipework would lose pressure, and you may have an explosion occur. Overall, you don't want a compromised payload
bay. As a sidenote, one of the things that many
people have pointed out are these 2 struts on the Payload Bays during production. These have been used since Ship 25, and may
suggest that the door requires extra support during the production process to prevent it
from sagging Once stacking of the vehicle is completed,
these are removed and the areas where these are mounted get cut off. So, these new modifications are yet to be
tested out in real life, but these are definitely things that we believe should eventually go
through some actual structural verification testing. We'll need to keep an eye out for a potential
test article featuring the payload bay that would undergo testing. This more than likely won't happen before
the first Orbital Flight though. Well I guess it doesn't really need to especially
since ship 24 25 and 26 can't deploy satellites so these changes won't really come into play
for a while. Yeah, exactly. Now, this is only when some of Ship 24's issues
began. Another section of the Ship that SpaceX did
not structurally qualify before integrating it with the vehicle was the aft section. Now, I'm not taking about thrust ramming the
dome. The unpressurized skirt area is a key area
of concern because it is a major component of what would be considered the Starship's
interstage. I'm not sure if I need to explain why it's
important to avoid a collapse of the interstage 1 minute into flight during MaxQ
So SpaceX constructed a test article to test out both the skirt's structure and the aft
flap hinges. A 4 ring aft sleeve that matched Ship 24's
construction was developed and sent over to the Can Crusher at the end of September in
2022. And with this test came yet another new configuration
for the can crusher. Gotta love how versatile this testing structure
is. In order to test a Starship aft section on
the can crusher, SpaceX needed an adapter in order to interface with the 20 hold down
positions which are normally tailored for booster testing. This black ring was delivered several months
in advance for this job. It would later have adapters for the 20 clamp
positions installed so it could sit on top of the can crusher mounts. The cap was modified as well. They added an appendage that would allow it
to interface with the mounting positions for the aft flaps of the Starship similar to what
we saw on the Nose cone jail in part 1. This allows realistic flight loads to be placed
on the aft flap mounting points while the cap is being pulled down by the hydraulic
pistons So, with it on the Can Crusher, we believe
that testing was conducted on October 7th, when Remedios Avenue was closed for testing
and an aerial work platform was presumably set up with a camera to watch the article. After the test, many people noticed that some
of the ring welds had dented inwards. This was a structural failure technically,
and it was unclear at the time what their next steps would be. What most people didn't notice is this photo
from Mauricio for RGV Aerial Photography when the article returned to the Dome Yard. Not only had the aforementioned ring weld
dented inwards, but so had the area around the Quick Disconnect panel. The Quick Disconnect, or QD, is used to supply
the vehicle with power, liquid, gases, and other consumables. There's a lot of very delicate pipework behind
this, so... this is actually really really bad. yeah I mean that's one way to put it. SpaceX had to get to work right away to find
a solution because this directly impacts ship 24 and therefore, the first Orbital Flight
Test. So this test article went into Tent 2, and
we got a look into the tent a couple weeks later to see that stringers were being added
all around the QD area after using hammers to bang out the dents. The actual QD panel appeared to have been
removed and replaced as well. When it went back to the Can Crusher, it looked
like this. Now, if you've been watching this program
fairly closely, you'll know that no Ships look like this. So my best guess would be that SpaceX did
a quick fix to allow flap hinge testing to continue. And it seems that testing went well! This article was removed from the Crusher
and still remains in the Ring Yard as of March 2023. But there was still an issue to address, the
QD and ring weld issue hadn't actually been resolved, and if the quick disconnect was
to rupture during flight and the pipework was to get damaged, well I don't think I need
to tell you what a mixture of oxygen and methane likes to do in an enclosed area, because the
QD pipework is above a false ceiling layer inside of the skirt where many electrical
systems can be found. You would also likely lose pressure in much
of the pipework, and some of this is directly connected to the engine feed pipes. Over at the Suborbital Launch Site, a tower
of scaffolding was being erected around Ship 24, and tiles were being removed around the
lower 3 rings of the aft section. By doing this workers able to access to the
area directly above and below the ring welds. Once the tiles were removed they welded a
doubler plate over the ring welds which is the only real alternative to placing stringers
over the area which is not an option on the protected side of the ship without some major
work. So this was at least part of the solution. For these top 2 rows of removed tiles, we
never actually found out what they did, but presumably some kind of reinforcements were
added on the ring welds. We then saw the tiles get replaced and the
scaffolding would eventually come down. After this, the work on Ship 24 went silent
for a while because it was time to qualify these changes before anything more happened. So of course, yet another test tank was produced. Ship 26.1 is a test tank made out of a Starship
aft section and a forward dome just to be used as a testing interface, like B7.1. Our first sign of impending design changes
was this photo from Starship Gazer looking into the Megabay. Crews were measuring out areas around the
QD panel, and a later photo would show that doubler plates were added around all 4 corners,
increasing the thickness of the area likely to around 8mm. S26.1 also had doubler plates, like we saw
added underneath S24's heatshield, on the lower 3 ring welds. I don't think many people realized this at
the time, but S26.1 was critical in order to confirm that Ship 24 would be able to stay
stable during its flight. We have previously discussed how strain gauges
are used to measure deformations in the steel, and the placement of these definitely tells
us what SpaceX was looking at. We can see 2 strain gauges by the Quick Disconnect,
some more up by the weld for the aft dome, some on the stringers that reinforce the aft
dome weld, and some more by the doubler plates that were put over the ring welds. S26.1 was moved to the Masseys testing site
and conducted at least 1 test on December 21st, 2022. It might have been tested more, but due to
the lack of coverage out at Masseys at the time, we can't be sure when that would have
been. The good news is that S26.1 seems to have
passed testing, and SpaceX was able to proceed with adding these modifications to S24. Well if this test article had of failed, they
could have just skipped over ship 24 and then went to ship 25 next right? Well It's not that simple. And this is one of the things that we hadn't
quite anticipated back when we started looking at the 26.1 test article a few months back. Here is a photo of Ship 24's aft section,
and we're going to look at the welds a bit. We can see the dashed vertical welds which
indicate there are 96 vertical internal stringers on this section. Alongside these stringers, we can count 8
hoop stiffeners. Together, these form the primary reinforcements
in the aft section. There are others around the aft flaps like
this large weld doubler, and this is because the hardware to support the aft flaps makes
it so hoop stiffeners can't pass by. Anyways, 96 internal stringers and 8 hoop
stiffeners. Remember that. Looking at Ship 25's aft section, we can see
it when it was being flipped here and see the same 96 internal stringers in addition
to 6 hoop stiffeners. At this point in time the 2 located in the
middle of the barrel were yet to be added, but looking at Ship 25 later on, which is
much more difficult, we can see they are still present. They are just added later on. Onto Ship 26 then. We can see the same stiffeners like previous,
and it's missing a couple that would be added later after the point this photo was taken. Ship 27 is next. It's the same too. Over to Ship 28, in this photo it's upside
down and is missing a couple of them like Ship 25 when we talked about it, but these
would eventually be added, making this the same too. I think you can see where I'm going with this. All of the aft sections had the same general
reinforcements, simply because without any structural testing, how would SpaceX know
to change anything? So now, every single aft section that had
already been produced needed to receive the same modifications S26.1 had, which at the
time was at least up to Ship 30 ish. To review, that meant 4 doubler plates would
be added on the 4 corners of the Quick Disconnect panel, a frame piece would be added to the
top edge of the quick disconnect panel, and the lower 3 ring welds on the vehicle would
all have doubler plates put overtop. Ship 24 is now visible with the doublers around
the QD panel and the ring welds, like 26.1. Ship 25 is visible with the doublers around
the QD panel and... well, they started on the ring welds. Ship 26 has them on the QD and ring welds,
just like the previous two Ships. Ship 27 has them in those spots too. Looking into Tent 2, we can see them on Ship
28. In tent 2 once again, we can see them on Ship
29. If we brighten up this photo inside the Starfactory
a bit more, you can even see them on Ship 30. Lets be clear this wasn't an issue with Ship
24. This wasn't an issue with Ship 24's generation. This was an issue with Starship as a whole,
and everything was impacted. Okay hold on a second you said that they've
already finished all of these reinforcements on all of the ships but you also said that
they only started on ship 25. Well, that's true. Most people haven't quite noticed it, but
when Ship 25 returned to the Highbay to receive its 6 Raptor 2 engines, SpaceX did start adding
the reinforcements on the aft section while they were sealing the payload bay door shut. But, they don't actually seem to have finished. Looking at Ship 25, you can see that they
only ever put this small doubler on the middle, in addition to the doublers around the QD
plate. Up at the PEZ dispenser door, the cover was
never actually completely welded on either. It looks like crews started doing the final
weld pass, but we can still see very visible parts that weren't welded. This was weird at the time, and honestly,
it still sort of is. Maybe it's suggesting that SpaceX hasn't intended
on flying Ship 25 for a long time, or maybe it's looking too deep into this. Either way, it's quite strange. Overall, SpaceX dodged quite a few bullets
with all of their Ships because thankfully these design flaws didn't force them to abandon
every ship that was currently under production. That's one of the benefits of stainless steel. What is a bit concerning here is that such
a seemingly large disconnect between processes was allowed to happen. And, as Zack mentioned at the beginning of
this investigation this was a direct result of Ship 20 and Booster 4 being scrapped. If we look back to March of 2022, the retirement
of these two vehicle meant that SpaceX now wanted to rush out the new ship and booster
which happened to both feature some pretty major upgrades. In doing so, the vehicle manufacturing seems
to have taken priority over vehicle testing and design qualification testing, which I
think was part of the long-term cause for these issues with Ship 24. Instead of verifying these new designs to
make sure that they were a-ok, the designs were implemented into the vehicles right away. To me it seems that SpaceX had at least some
degree of confidence that these designs would be fine, and their simulations and math may
have backed that up. And by no means do I think I know better than
them, but I just feel like this sudden rush with Ship 24 and Booster 7 put a lot of crucial
things on the backburner. We are in March 2023, and SpaceX still hasn't
even finished with verifying absolutely critical components of Ship 24. And the reality is that with rapid iteration,
sometimes things like this might happen, nobody has really done anything like this before. The solution to this, is that SpaceX will
likely put a bit more priority on this structural qualification, which will ultimately save
time and negate the need to go back and retroactively modify 7 aft sections at the Production Site. But with this aside, they have to finish up
verification testing, so it's time to look at the last couple test articles on the agenda. One of the test articles that SpaceX tested
at the end of 2022 was Booster 6. Booster 6 was skipped in favour of Booster
7 at the end of 2021, and was stacked to become a test tank in December of that year. It's made out of a Booster forward dome and
a Booster common dome, however, the common dome was capped off to create an enclosed
tank. B6's counterpart, which we’ve heard referred
to as "6.1" was a Ship leg skirt originally believed to be assigned to Ship 22. Ship 22 is believed to have stolen Ship 23's
leg skirt during the production process, so this one was left roaming around. These parts sat around for about a year until
the end of 2022. The skirt received reinforcements to make
sure it didn't collapse during the test, and because it was an old and irrelevant design,
collecting data about it didn't really matter. But, the integration with B6.1 would be structurally
qualifying the connection between the Ship and the Booster, in addition to the Booster
half of the interstage which still hasn't changed all too much from B6's design. It was assembled on the Can Crusher and the
cap was placed on top. November 14th and 15th are believed to be
when this was tested, and as far as we can tell, it passed perfectly fine. There have been a few more trials with various
test articles since this, but for the sake of this video and the uncertainty of what
is still happening with these, we're going to talk about just one of the other tests
SpaceX is in a rush to complete before this launch. Ship 24 implemented a new design of nosecones,
now using fewer, stretch-formed panels instead of many stamped panels like was on Ship 22
and prior Ships. The old design was tested in the nosecone
testing cage back in 2021 using Nosecone 12. So, SpaceX waited quite some time to actually
test this, but they did choose to test it and truthfully for a while we were a bit worried
that they wouldn't. Nosecone 31 first deviated from the standard
production process in November of 2022, when SpaceX suddenly stopped putting heatshield
tile pins on it. In the coming months, the flap hardware was
developed and we eventually saw the tip get removed, just like NC12 a couple years back. It would roll over to the Sanchez site on
February 14th, and was then placed on the nosecone cage base. I'll let Zack discuss how this testing structure
was configured for NC31. Well its important to note the obvious fact
that this nose cone is missing the payload section. So since SpaceX is only trying to verify the
structure of the tapered nose section they had to shorten the testing structure to about
half of its original height. The nosecone has a single 9 meter ring added
below the nose cone section. This ring has an access hatch on it to allow
SpaceX workers to have a way to enter inside of the structure to service the hydraulic
pistons inside. This ring section is welded down to the base
structure with extra reinforcements on the outside, and stringers on the inside to ensure
that if this test article buckles under the pressure, it won't fail due to this ring which
isn't actually part of the test. Inside of the structure, there are 3 small
pistons on top of a platform that will be used to pull down on cap from the inside. Up, top they again have two pistons to pull
the nose cone in different directions to simulate re-entry forces so other than the changes
that were made to the test structure itself and the lack of a 5 ring stack, this is relatively
the same as what was done with the SN12 nose cone. We likely won't see this test when its performed
even though there are camera's pointed at it from a distance. It will be very hard to determine when it
happens, but its safe to say that it will occur before the first launch, if it hasn't
already. And that's good news because once that's completed
we can confidently say SpaceX has now structurally verified every section of the booster and
Starship…minus the 5 ring payload section but hopefully that won't matter for this first
Orbital Test Flight. On January 23 of this year, SpaceX completed
their first ever full stack wet dress rehearsal. Successfully filling the Starship first and
second stage with liquid propellants and taking them through a complete launch count down
sequence. This included everything that will happen
during a real count down to T-0 other than retracting both quick disconnects, and igniting
the Super Heavy Booster's 33 raptor engines. It was incredible how smooth this went and
I'm sure that completing this on their first attempt really got the team fired up. And if that some how that wasn't enough excitement,
on the 9th day of the second month, SpaceX finally performed a not quite 33 engine Static
fire test on the Orbital Launch mount. This was a relatively low throttle test, peaking
out at about 47% of available thrust. I say available thrust because SpaceX manually
aborted one engine, and another auto aborted for unknown reasons. Overall, everything went incredibly well and
if we are lucky, we should see the first launch occur sometime in April and I want to personally
wish them luck! So where does that leave us? Well if you get one thing out of this episode,
we hope you were able to gain a better understanding of how Structural Qualification Testing plays
a major role in the Starship development process. Its very critical for this to be performed
properly. And every time SpaceX makes a major change
to the design of the booster or Starship, we should expect to see them begin the qualification
process all over again. I can guarantee there will be A LOT more of
it to come. This is a pretty monumental task that SpaceX
is taking on here. Keep in mind there are at least 5 different
planned variants of the Starship which will do everything from placing payloads into orbit,
orbital refueling, return humans to the moon and hopefully send them to Mars as well which
will require both crew and cargo variants. This is something of far greater ambition
than what we saw accomplished with the Saturn V. And that’s kind of crazy because at its
peak, the Apollo program employed more than 400,000 people and required the support of
over 20,000 industrial firms and universities. The last time we heard, SpaceX has less than
2,000 employees working on the Starship Program. So if this kind of stuff interests you, than
you should probably come work for SpaceX because they need your help…like, yesterday. Anyways, I look forward to keeping you updated
on where this situation goes from here and hopefully Jax and the Ring Watchers will continue
to track these hard to notice changes because we really wouldn't be able to cover this topic
anywhere near as thoroughly without them. So Thank You Jax. In the meantime be sure to follow the Ring
Watchers on Twitter for more updates. If you enjoyed this episode, then do us a
favor and hit that like button and subscribe to the channel if you haven't already. I've decided to go full time with the CSI
Starbase YouTube channel which means you will likely see a significant increase in content
that we will be putting out in the coming months. If you would like to help support the channel
while I make this transition than you can do so by becoming a monthly supporter on Patreon,
or by joining as a member of the YouTube channel. Before I go, I also want to thank Chameleon
Circuit for their hard work putting together the detailed renders and animations used in
parts 1 and 2 of this deep dive investigation and also to Geoff for consistently improving
the quality of the production that goes into these episodes every time we release a new
one. Hopefully all of you returning viewers can
appreciate the way he’s able to level up each time as well. And speaking of hard work, huge shoutout to
Labpadre, NasaSpaceflight, RGV Aerial Photography, Starship Gazer, Cosmic Perspective, and all
the other Starbase Photographers and 3D artists who's content was used in this episode. Thank you for doing what you do to document
history in the making. You can find links to all of their various
channels in the description Last but not least, thank you to Squarespace
for Sponsoring todays deep Dive investigation. Alright everyone I'll see you all next time. For now, this is Stage Zero Zack - Signing
off
