SpaceX initially planned to use conventional inclined flame deflector for Starship launches.
SpaceX uses shaped flame deflectors for Falcon 9, Falcon Heavy and every vertical Raptor static fire test stand.
What made them change their mind and what makes Starship special?
1/🧵
Reuters claims that SpaceX's injury rate is 2-6 times higher than industry average.
White-hot take:
It's very easy to be safe by sitting there and doing little to nothing useful.
1/🧵
Enjoy our MEGACUT Slow-Mo of
#Starship
IFT2. Huge thanks to the massive Everyday Astronaut,
@considercosmos
and
@rotorvisual
teams for making this video possible! And again, HUGE congratulations to
@SpaceX
/
@elonmusk
for making so much progress on such an ambitious rocket!
This is not a render. This is not a simulation. This is
@SpaceX
’s first integrated test flight of
#Starship
with the Super Heavy booster, the world’s largest and most powerful rocket to ever fly. This
#slomo
is from our 8k tracker shot by
@considercosmos
.
SLS and Orion are in trouble.
It appears that NASA and USG are repeating mistakes that caused Shuttle accidents.
Short version:
- Original compromises that were required to gain approval for SLS and Orion? check
- Resource constraints? check
...
1/8
Destin has questions about Starship HLS architecture.
Hopefully, this thread will answer them.
This paper is mandatory read for any space enthusiast:
Very short version of this paper 👇
1/🧵
B7:
> survives implosion
> survives explosion
> sets multiple world records
> digs a pit in FONDAG
> does a cool flip
> sacrifices itself to help future boosters
S20 to S25 evolution of TPS:
- horrible gaps are fixed
- gap filler added
- hexagonal tiles are rotated 90°, which allows simpler tile layout
- L shaped tile is gone
📸:
Our modules are available in a variety of dimensions with a focus on 4, 6, and 8-meter diameters to accommodate launch vehicles flying today and the next generation launch vehicles of tomorrow.
This is the flame deflector used for the Apollo 5 mission, with the Saturn IB AS-204 sitting above it. Will SpaceX use something similar to this for
#Starship
? If so, it would have to fit between the OLM legs and be removable to keep access to the booster's engines when needed.
.
@ViasatInc
's Viasat-3 Americas satellite launched May 1 suffers major antenna-deployment anomaly. After more than a month of effort, it's still not fixed. Possible $420M insurance claim and a serious blow to Viasat's near-term growth plans.
- NASA fails to develop a critical technology D for over 50 years
- NASA asks private company S to develop D
- NASA doesn't fully fund development of D
- S wants to make return on development of D by selling it to other companies
- NASA complains they can't release D for free
RocketLab: Falcon 9 is too big. We're going to compete by going smaller.
SpaceX: We need to dial Raptor's chamber pressure to 11 to make Starship even bigger. Actually, make that 12.
So, Falcon 9 booster is *less* likely to get destroyed flying to space and back than standing on a barge and doing literally nothing.
Big L for downrange recovery, giant W for propulsive landing.
No wonder Starship and Super Heavy use only RTLS.
During transport back to Port early this morning, the booster tipped over on the droneship due to high winds and waves. Newer Falcon boosters have upgraded landing legs with the capability to self-level and mitigate this type of issue
Super Heavy uses 33 state of the art, highest pressure engines. Super Heavy is *much* more likely to have engine failures early in development than other rockets.
This problem is so big that SpaceX made special engine failure indicator for launch live streams.
2/7
The problem is when LV sits on the launchpad and exhaust is redirected sideways: sound is directed more towards vehicle.
Yep, contrary to the popular belief, redirecting exhaust flow sideways increases acoustic load on the vehicle.
Nobody is going to nationalize SpaceX, DoD doesn't need to nationalize SpaceX to own Starship the same way you don't need to buy Apple Inc. to own IPhone.
Rocket noise is generated in the mixing region, it's directional, with the highest noise levels at an angle of ~45 degrees from the direction of the exhaust flow.
It's good because in flight most of the noise is directed away from vehicle.
📸
@TrevorMahlmann
The answer is that NASA is forced by law to use RS-25 for SLS ().
@Brehmel
, if RS-25 is so good, why there is a law which protects it and forces NASA to use it?
Rocket noise power is proportional to rocket mechanical power and acoustic efficiency.
Contrary to another popular belief, flat normal plate close to the engines is the best at reducing acoustic efficiency
"N1 also used a lot of state of the art engines, but is used shaped flame deflector!"
N1 also never performed integrated engine testing. No integrated engine testing -> no engine failures during testing -> no engine service after testing.
7/7
Super Heavy needs a lot of engine service and often.
SpaceX uses Orbital Work Platform to perform engine service on Super Heavy without moving it from Orbital Launch Mount.
3/7
"SpaceX representatives said that the fundamental propellant transfer technology is not new or unique but requires engineering time and development effort to fully design and test "
Prediction: SLS will be cancelled between Artemis 3 and Artemis 4, most likely together with Orion, without cancellation of Artemis, HLS and Gateway.
You can quote me on that.
Orbital refueling, almost magically, solves this problems: Starship only has two (similar) stages, 3 dissimilar engines, one propellant mix.
Incredible simplicity.
Development and fixed costs are low.
5/11
- Fluctuating priorities? check
- Schedule pressure? check
- Disregarding of known safety related design flaws? check
Hard to believe, right?
Long version:
In 2005 Crew Survival Office stated that crewed vehicles with SRB's are very unlikely to meet safety requirements.
2/8
Apollo lunar architecture, like any single launch crewed lunar architecture, is incredibly complex: 8 dissimilar propulsion modules (stages), ~7 dissimilar engines, 4 different propellant mixes. This means fixed and development costs are absurdly high.
3/11
How much launches exactly do they need?
It doesn't matter, tanker launches are very cheap and not mission critical.
Also, they don't talk about exact number of launches not because there is a communication problem, but because literally nobody knows.
9/11
Starship has no mass problem: even though Starship stack is only a little bit bigger than Saturn V, it can deliver ~100 tons and ~1000 cubic meters of payload to lunar surface and back, in fully reusable mode! Extraordinary utility at low marginal cost!
6/11
Moreover, Apollo-like architectures have mass problem: even fully expendable Apollo stack has nearly zero payload capacity to lunar surface and back. This means marginal mission cost is also absurdly high, and whole thing is basically useless outside of politics
4/11
It's hard to explain why SpaceX claims that SuperHeavy is ~2.63 times louder than SLS, while only 1.37 times more thrustful (SpaceX overstates noise from SH? 🤔, Or maybe NASA understates noise from SLS? 🤔).
Let's look at SLS noise assessment.
12/
Can you guess how NASA solved this problem?
Instead of changing vehicle design to make it comply with safety requirements, they simply removed safety requirements CSO was talking about.
BTW, SLS uses two world's largest SRB's.
3/8
Musk: "I think there's a good chance we start deploying Starlink V3 satellites next year, roughly a year from now."
"Hardest about" Starship is landing successfully, so "we can start launching satellites before that."
What about reliability?
Depot and tanker launches are not mission critical. There is no mission failure if one of the tankers fails.
Additionally, orbital refueling provides huge amount of opportunities to perform adversarial testing of major architecture components.
7/11
Bro casually compared sound intensity level to A-weighted sound pressure level without any unit conversion at all 💀🤣
Those a different physical quantities. It's like comparing power to force.
Here's I post I made on SpaceX's upcoming launch, including a revelation from a FOIA that shows FAA and SpaceX have significantly underestimated harm that will be caused due to sound impacts
Dissimilar hardware is evil. More dissimilar hardware -> more evil. The best part is no part: it weights nothing, it costs nothing, it can't go wrong.
Low utilization rate is evil. Less rocket launches -> more evil.
2/11
This means maturation is highly accelerated. This leads to higher reliability and lower cost.
Many launches per mission is a good thing, actually.
8/11
Orion's heat shield behaved unexpectedly during A1, but uncrewed flight test costs ~$4B and roughly two years, so for crewed A2 mission NASA will either use the heat shield with a known design problem, or a new and not flight proven heat shield.
6/8
Due to delays,
@NASA
is mulling over plans to move the
@NASAArtemis
inaugural Lunar landing mission from the 3rd to the 4th flight. I would also move the 1st crewed mission from the 2nd to 3rd mission. For safety, the 2nd flight should also be uncrewed.
SLS has another design flaw: It cost too much and it can't fly often, so Block 1B and Block 2 will introduce a lot of new hardware (RS-25E, EUS, BOLE SRB's, ML), without uncrewed flight tests, which is very unsafe in my opinion.
5/8
Just a reminder that Orion capsule mass is only 10.4 metric tons, cargo Blue Moon can deliver 20 tons from LEO to lunar surface and back to NRHO.
SLS is not needed.
Orion is also not needed, albeit slightly more complicated to replace it.
Wait you’re telling me that some people actually think you can use lunar landers, (ones which doesn’t actually even exist and haven’t flown yet) that has no abort system and no heatsheild, to replace a crew rated launch vehicle specifically designed to launch people to the Moon.
Orbital Work Platform requires ground under OLM to be flat enough for SPMT's. SpaceX can't use OWP with shaped deflector.
The first thing SpaceX tested after installation of flat normal water-cooled stainless steel flame deflector is OWP.
4/7
All three achieve X at the cost of 100 injuries per company, but B and U somehow have twice lower injury rate.
How?
U hired twice more workers than S or B, and half of them did literally nothing. B worked twice slower and achieved X two times later than U or S.
3/9
SpaceX makes ~400 engines per year. BO makes ~10 engines per year. SpaceX launches ~100 times a year. ULA launches less than 10 times per year.
SpaceX employee is like 100x worker.
8/9
In my opinion, injury rate (injuries per 100 workers per year) is a terrible loss function to optimize for.
Imagine 3 companies: S, B and U. All three want to achieve some goal X and all three have the same safety culture.
2/9
Why SLS uses SRB's? That's because instead of optimizing SLS and Orion for crew safety, long term operational cost and capability, NASA optimized them for quick and cheap development, for political reasons.
I don't believe safety is their top priority.
4/8
SpaceX delivers more then the rest of the world *combined*. They compete against the rest of US, China, Russia, EU, Japan and India. Just SLS+Orion *alone* employ more workers than SpaceX.
7/9
Second reminder that FWS's BCO reevaluation has nothing to do with "the pad yeeting itself into sensitive habitats".
Installing proper water deluge before IFT-1 doesn't help to avoid this BCO reevaluation and doesn't accelerate approval process.
1/4
Fact that FAA work will be done inside 7 months is incredible but, the pad yeeting itself into sensitive habitats will trigger the FWC to delay your project further. If they waited for IFT-1 to have a proper deluge they’d probably be prepping IFT-3 now, at least. Not on the FAA
Ask yourself NASA, What would Elon Musk do? If his Moon rocket had a cracking failure of its critical heatshield and loss of large chunks during Earth Entry? NASA must not fly Artemis II with a crew without a flight test to prove the heatshield is fixed.
There is no such a thing as "established industry standard" for fully reusable launch vehicles. Starship is the first one.
Do you really expect SpaceX to follow "established industry standards" designed for expendable launchers?
1/2
"Can't they just roll SH to build site for engine service?"
Technically they can, but it requires 2 evacuations, 2 risky and dangerous SH lifts and, most importantly, 2 road closures. They have very limited amount of road closure hours per year.
5/7
"Anton, this is just imaginary scenario, in reality injury rate loss function is not so bad"
Current state of space industry:
80-90% of launch (by mass) is performed by small company called SpaceX.
Majority of useful satellites is operated by SpaceX.
6/9
Saying "injury rate is good at reflecting safety culture" is like saying "I don't really care how much people are injured to achieve X, just make them less noticeable by spreading them through time and or between more people"
5/9
Tightly clustered engines behave like a one big engine, and bigger engine noise has lower frequency.
Human hearing is less sensitive to low frequencies.
Number of launches is very sensitive to a lot of factors: season, Earth and space weather, Moon phase etc.
Imagine if depot needs to doge some orbital debris, and now it's stuck in less optimal orbit.
10/11
@Geoffre33707336
@sufy1000
@NASAArtemis
@NASA
Despite its flaws I do genuinely believe SLS is the safest crewed LV to fly, second to the Atlas V.
The number of redundancies in the system & the contingencies drawn up are astounding.
I have good news:
Raptor can, in fact, change film cooling independently of MCC pressure, and it can do this while running.
@Phrankensteyn
@BellikOzan
@Mqrius