The old SpaceX Starship wasn’t capable of an orbital flight.
How did SpaceX make the new Starship booster capable of flying to orbit?
What secrets can we find? Let’s dive right in!
My name is Felix, and I am your host for today's episode of What about it.
Today we’ll uncover all the essential changes SpaceX implemented on their latest Starship booster to be able to reach orbit!
We’ll go all out and compare the old Starship Super Heavy Booster 4 to the all-new Booster 7!
Starship Updates
SpaceX is in the hot phase of getting everything ready for an orbital Starship launch.
Time to look at the main differences between two generations of Super Heavy Starship boosters.
Time to put the two to the test and see what SpaceX changed and why to make the orbital launch happen.
Chief, the WAI cam operator, was on site for all of us again.
This is footage he produced on June 28th.
From left to right, we have Booster 4, which is being readied for a rollout to the rocket garden right now.
This might even have happened by the time you watch this episode.
Meant initially to do the orbital flight, this booster is now obsolete.
As soon as SpaceX realized they had more time to prepare for the orbital flight due to the late FAA approval,
they graded the booster down to a ground test article.
Now, it’s little more than a good-looking prop, so it’ll likely be moved to the rocket garden.
Next, we have the orbital fuel farm.
Surveyors are currently watching the tank foundation closely.
Since fueling began a few weeks ago, the foundation on which the large GSE tanks are sitting has been under close watch by SpaceX.
The commodities being filled into these tanks for the upcoming static fires and the orbital Starship launch weigh thousands of tons.
The foundation is settling and sinking under the immense weight.
This is normal up to a certain point.
If the foundation sinks too much, something needs to be done.
I am still researching the matter, and the reports are a bit inconclusive.
I’ll keep you informed! In the foreground, you can see BN7.1 on the can crusher and undergoing a cryogenic test.
A lot is happening at the same time.
I explained it in the last episode.
Watch it if you want to get all the details on how the can crusher works.
7.1 didn’t give in so far. So, testing will likely continue.
Finally, on the right, we have the Texas Mechazilla, and behind it, the orbital launch mount and SpaceX’s booster 7 on top.
Venting can be seen. Booster 7 has finished more testing.
And here’s what SpaceX has been focussing on in this first test.
The so-called ullage gas thrusters.
One of many changes compared to booster 4. It’s SpaceX’s way of reducing complexity and saving weight.
How does it work? The whole concept behind it is surprisingly simple.
The RCS or reaction control system can be found on any spacecraft that needs to control its attitude in Space where there’s no atmosphere for
aerodynamic control. Here you can see the Draco thrusters used on Crew and Cargo Dragons test firing 11 years ago when the capsules were in early
development. These Thrusters are used to change attitude and position while the craft is in space.
And as you can see, a lot of hardware is required to make it happen.
Avionics, fuel tanks, thrusters, and the plumbing to connect all of it together.
In Dragons' case, the RCS is run by hot gas thrusters.
So, the thrusters burn fuel. Hypergolic fuel.
Hot exhaust.
Falcon 9 Boosters have an RCS too.
And SpaceX’s current workhorse uses cold gas thrusters.
Cold gas means that there’s no combustion happening.
Nitrogen is released at high velocity.
Hence the name cold gas thruster.
This needs separate tanks, too.
A separate system that needs to be brought up to Space, raising the complexity of the design and the weight of the hardware itself.
Now, SpaceX is doing this instead.
Do you see that brownish material surrounding the vent on the booster just below the fins?
That’s insulation. It is one of four vent outlets for SpaceX’s booster ullage gas thrusters.
Positioned almost at the top of the booster to increase the leaver, these vents release ullage gas from the engines,
also used to pressurize the main tanks.
It has the same effect as a cold or a hot gas thruster as seen on Dragon and Falcon 9,
with the significant exception that it doesn’t need a rocket motor or extra tanks and commodities.
It just uses what’s already there.
Gas that the Raptor engines already divert back to the main tanks for autogenous pressurization.
One change here compared to booster 4 is the added thermal insulation around the vents.
Looking at it up close shows that it seems to be hand cut.
Uneven borders. This, in return, tells us that it must be a relatively soft material.
What kind of material could this be?
What do you think? As always, tell me in the comments!
Elon Musk has now also changed the design of the Starship upper stage after Tim Dodd, the Everyday Astronaut,
asked him for confirmation if this was only planned for the booster.
Sometimes it just takes a smart YouTuber to get Elon thinking again.
Good job, Tim! Next up, we have the grid fins as a major improvement of the orbital Super Heavy booster design.
These are booster 4 and booster 7 side by side.
Both when they were sitting on the orbital launch mount at SpaceX’s Texas Starbase, and both pictures show the grid fins.
In Super Heavy’s case not made from Titanium as on the Falcon 9 boosters but instead made of Stainless steel, which is likely to save costs.
The Falcon 9 grid fins are the world's largest single pice titanium cast objects.
Not cheap at all. And in direct comparison, you can see a significant difference between the two booster grid fin designs.
The new Booster 7 grid fins are much denser, meaning they have more grids, and they’re thinner, making them lighter.
Mauricio from RGV Aerial Photography was up in the air again,
taking one of his incredible top-down pictures of Booster 7 on the orbital launch mount.
From above, you can see the increased grid density even better.
If you’re not a flight supporter yet, check out Mauricios Patreon and help him fund the next flights!
A link is in the description!
Lunar Caveman used Chief’s footage to measure the new design accurately, confirming that the dimensions seem not to have changed at all.
As you can see, though, the grids have increased a lot.
To be precise, from 24 full grids on the old design to 60 on the new one.
Not counting the half grids on the outside.
In theory, this more than doubles the force the grid fins can apply to change the booster's angle while coming in for a landing.
Thank you, Lunar Caveman!
On we go with the engine setup!
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The Booster engine configuration has changed quite a bit.
This is booster 4. It’s an image Elon Musk tweeted out on November 16th, 2021.
He wrote 12 million pounds of thrust at liftoff.
It shows 29 Raptor 1 engines configured in two groups.
An outer ring of 20 fixed boost engines and an inner cluster of 9 engines able to gimbal and thus steer the booster on ascend and descend.
There are several radical changes for the orbital Super Heavy booster 7.
The engine itself, for example.
Raptor 2. A vastly improved design compared to the early prototype Raptor 1 engine.
Routinely operating at 300 bar main chamber pressure, whereas Raptor 1 was at around 268 bar for peak pressure.
There’s a huge difference between a record attempt and routine operation.
The next essential difference is the engine count.
33 Raptors instead of 29. 230 Tons of thrust each at liftoff.
More than Raptor 1 and a total of 7590 tons.
A fully fueled Starship and Super Heavy stack weighs around 5000 tons.
This leaves the SpaceX Starship with an initial thrust-to-weight ratio of approximately 1.5.
In comparison, SpaceX’s Falcon 9 rocket is at roughly 1.4 to 1.5 as well.
So, even though a Starship is massive in comparison, weighing as much as 10 Falcon 9 rockets at liftoff,
it still keeps the same thrust-to-weight ratio.
The Saturn V Moon rocket weighed in at around 2800 tons at lift-off and created around 3447 tons of thrust with its 5 F1 engines simultaneously.
So, only 647 tons to spare. That’s why it looked like slow-mo footage when it lifted off.
This won’t be the case with SpaceX’s Starship.
Especially with the new booster design.
It’ll zoom up into the sky like a Falcon 9 rocket even though it’s a giant even compared to the Saturn V. On we go with another important external
change. Aerodynamics and COPV setup.
Even at first glance, both boosters look very different.
Here’s a stunning picture taken by Chief on June 23rd.
The new Booster 7 is on the left, and the old Booster 4 is on the right.
Chines, those elongated vertical aero covers on the outside of booster 7 have appeared.
This is due to different COPV placements.
Those black tanks, responsible for engine spinup in flight,
have been arranged in a vertical configuration on booster 7 for aerodynamic reasons,
replacing the box-like covers found on booster 4. I won’t go into detail on it, as it would be too much for today’s episode,
but if you want to know the full and fascinating reasoning and why the entire Super Heavy booster will act as a wing,
watch the episode I did earlier this year!
I’ll link it in the end card for convenience, so watch this episode until the end.
The HPU Covers became more aerodynamic.
Don’t you love acronyms?
Sometimes the rocket industry can be full of them.
The HPUs are for TVC movement.
Plain English: The hydraulic pressure units supply the engine thrust vector control system with the needed pressure for the hydraulic engine gimballing.
The TVC makes the engines move to give the rocket the ability to control its flight.
Last but not least,
we can see that the structural bracing on Booster 7 has increased compared to booster 4. These vertical metal stripes on top,
between the two main tanks, and on the bottom of the boosters are for structural support.
They make the hull stiffer in places where it’s needed the most.
At the top to support the Starship getting stacked on top to give more strength to the catch points between the booster's grid fins and to support
the grid fins themselves, which pull on the hull quite a bit.
On Booster 7, the bracing fades out between the grid fins.
On booster 4, it had a hard stop all around the top.
The same goes for the bracing between the main tanks.
On Booster 7, it’s almost double the width compared to booster 4—a steadily evolving design.
Those are only the visible main changes.
There are likely hundreds of other changes hidden from our observation and Chief's camera.
To sum it up, booster 7 is more powerful due to Raptor 2 being the more powerful engine compared to Raptor 1 and due to 4 extra engines in total.
It has a largely changed aerodynamic design due to the changed COPV placement and aerodynamic covers acting as a wing.
Booster 7 has the more advanced ullage gas thrusters.
And last but not least, it has a much stiffer hull.
It is much more capable of performing the orbital flight, which should happen within the next two months, according to Elon Musk!
Today’s Episode is a perfect example of SpaceX being efficient in their approaches.
But what about your efficiency?
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