Eric Berger judges it a huge success.
I’m sure they learned a hell of a lot from it, which is the purpose of a test flight. The only failed test is one from which you learn nothing.
Per some of the stupid comments, the notion that Elon is a white supremacist is lunacy, but there is a lot of lunacy in the world these days.
[Update a while later]
More thoughts from Eric, a couple hours after the first column: ” I no longer have any regrets about missing Apollo. I am thrilled to be alive at this very moment in human history.”
I would trade having missed Apollo to be twenty years younger, but it’s not an option. Fortunately, I’ve also almost made it to the the point at which I may be able to live a lot longer, and see a lot more happen.
Based on the comments section at Ars I often wonder who Eric Berger thinks he’s writing for? Frustration must hardly describe the feeling. Also just as weirdly the commenters seem content to go after one another rather than demand the author’s cancellation. Ars
TechnicaOdd.I’ve bee registered at Ars for over a decade, and have racked up several hundred comments over the years there, bus the last 5+ years has been an absolute shitshow at that site. Thank Ghod I had the foresight to never pay for a membership. Eric Berger seems to be the only sane person left there; I wonder if he’s looking for a way out?
I get a feel there may be some delay before we see the next Starship/SuperHeavy launch.
SpaceX is going to need time to review the data from this test before they can even consider remediation. Then some hardware may gave to be modified. Software certainly. And that will also require some review and test. Will the pause be as long as between IFT-1 and IFT-2? No I don’t think so. But I don’t expect another flight this year. Late January seems more probable. IMHO.
There is a lot of Elon hate out there. I have no idea why. Even on the Homebuilt aircraft group some idiot called him “the worst kind of bigoted sub-human being”. Stunning, well reasoned argument.
Some people are (idiotically) inferring from a recent Xheet and other things he’s done that he’s an anti-Semitic white supremacist.
I’ve been referring to the site for years as Ars Holica. Which could be construed to mean Fake Art in Latin.
Arse commenters hate Donald Trump, to start with. His Presidency drove many of them insane, and since the media was all in on “misinformation” and “disinformation”, they believed every bit of Orange Man Bad.
Musk has always been somewhat of a huckster, but they forgave that because electric cars. Then he bought Twitter because he was sick of the leftist spin on everything. Well, the commentariat already decided they didn’t like free speech any more, so they went after him–and since he’s also in charge of SpaceX, they struggle to decide whether they hate that too, or just that he’s in charge of it.
Stop mincing words, Ars is a commie hellhole. Sadly it also represents the “considered opinion” of the millennial cohort. Or cadre. Or whatever Marxist synonym for “group” you care to use. I wish Berger would leave the place, and that Clark hadn’t signed up, but either they agree with the general slant, or find the money compelling. (And then there’s that thing about embracing the power of “and.”)
I mean, even Berger has mentioned Musk’s “antisemitic comments” in his latest report without irony or any context whatsoever.
All the whining about so-called “antisemitic remarks” by what are most likely Hamas Fan Club members had gotta be the largest cognitive dissonance ever recorded. The whiners would probably readmit Musk to no longer being an unperson if he would donate some left over rocket parts to Gaza, and help thereby sponsor Hamas’ next slaughter of Jooos.
Before SpaceX, the destruction of the booster wouldn’t even be an issue, it was going to crash anyway. It strikes me as passing odd that they can switch to hot staging on such short notice. Especially since they expect to recover the Super Heavy. There must be some major reinforcement for the bulkhead if they expect it to survive hot staging that you wouldn’t need for conventional staging. Or maybe you do, to survive returning to the launch site.
The Peacekeeper ICBM used hot flyout staging for I/II and II/III separation. I was very, very involved with the staging problems for both PK and the subsequent Small ICBM. The biggest problem involved the loads on the upper stage nozzle by the reflected shocks from the lower stage forward dome.
We tried to recover all of the Peacekeeper Stage Is dropped in the Pacific off of VAFB, but only succeeded in getting one. IIRC, it was FTM-4, the fourth flight test missile. Whichever it was, the kevlar-cased stage was pretty beat up, but the forward dome didn’t sustain much damage – on the outside, that is. Inside, we found that the case insulation had eroded to almost the point of failure, an unknown phenomenon which would have threatened the fleet’s reliability had we not discovered (and subsequently designed for) it.
But the really huge thrust of S-II barely touched the S-I forward dome, and that was a 120,000 lb thrust solid firing against a 92 inch diameter lower stage dome. The exhaust stagnation temperature was way, way above that of the Raptor, and carried the bonus of aluminum oxide slag at hypersonic speed.
I would guess that the bigger design challenge for the Starship forward dome would be the dynamic pressure, given the gigantic chamber pressure of the Raptors.
I know the slits in the interstage are suppose to allow the exhaust and pressure to exit but it’s hard to imagine that all that pressure and heat does not affect the Starship engine compartment.
Michael, Scott Manley noted the extensive negative G’s the first stage must have experienced based on the rapid decrease in stage speed telemetry if accurate. This is leading me to agree there are ullage issues and loss if feed pressure that may have triggered subsequent engine failure.
However you raise a very interesting point. That perhaps a thermal imbalance may have lead to a pressurization issue that might require further insulation or a rework if the deflection dome interior.
This is the kind of insight that has to be earned as you have.
Rocket recovery, there was a time when just holding a stage together long enough was good enough.
There’s a 20,000 lb shield between the hot staging exhaust space and the upper dome.
The lengthy gyrations of Ship25 for about 60s after T+8:00 have to concern (legitimately) the FAA.
Either the automated FTS didn’t signal an abort (bad), or it signaled and the destruct charges were insufficient (also bad).
Either way the danger to Brownsville for launches now, and other populated towns & cities later, is very real.
My guess is that the FAA will now demand a physical demonstration with a 2nd stage flight text article.
They haven’t done a Starship landing since 2021, given the pace and extent of SpaceX design changes one of those might be required as well.
The 3rd party supplied telescopic video appears to show no upper stage “gyrations” until after the FTS. It also shows the header tanks survived the explosion, so that’s a different problem.
The idea that there’s a “danger” to Brownsville is fabricated. Both IFT-1 and IFT-2 exploded above the tropopause, and in no case could the vehicle make a magical power dive on Brownsville from miles away. So too, the explosive power of the stack is far less than certain haters contend. It’s not a nuclear weapon and is not going to kill the entire population of Brownsville and Matamoros, nor even SpaceX staff and observers much closer than that. Although it would set off car alarms for miles around!
“The idea that there’s a “danger” to Brownsville is fabricated.“
I, and the FAA will also, I suspect, disagree.
The FTS has to work *successfully* at all altitudes and in all flight regimes, from 1m off the pad at 1m/s all the way to orbit (or some specified point).
The orbiter is strongly built and has lifting surfaces, a new thing in launching, and SpaceX has to *prove* they can keep the general populace reasonably safe.
Rand has repeatedly argued against a disproportionate emphasis on safety, and I agree (I own his book), but the risk does exist and does need to be managed, particularly when the risk is to persons not involved, not near, or even aware of flight operations.
It is OK to be a fan, I am one myself, but the danger does not have to be “nuclear” (and where did that idea come from?) to need to be addressed.
Then you and the FAA would be wrong (I suspect the FAA knows, even if you don’t):
The “orbiter” is not strongly built. It’s made of 4mm stainless steel with stringers so it won’t collapse under its own weight, but it can wrinkle if not pressurized. In the troposphere, if the angle of attack rises above a certain point, the vehicle will disintegrate. The vehicle does not have lifting surfaces. Those are drag brakes used for attitude control during EDL and generate zero lift. Even if they were lifting surfaces, that’s not a new thing in launching. Perhaps you hadn’t heard about the space shuttle or Buran? And if they were lifting surfaces, the stack would break apart during launch.
This stuff’s not a secret. Read up on it.
As far as the nuclear comment, goes, Starship at launch contains 5,000 tons of fuel an oxidizer which can be described as “5 kilotons.” That’s lead many so-call journalists and “commenters” to describe it as equivalent to a 5 kiloton nuclear weapon. One well known commenter (not here) has repeatedly said if Starship explodes on the pas more than a million people will die. I mentioned it by way of example as to how absurd these falsehoods can get. (FYI, NASA may have originated the idea. I had a press pass to STS-1 and heard a NASA PAO say so.)
When describing the yield of an explosion, the term kiloton refers to the energy released by 1,000 tons of TNT. It isn’t about a thousand tons of propellant but a specific explosive. There is a very devastating type of weapon called a fuel-air bomb. It’s a weapon that disperses a fuel and the ignites it for a particularly big explosion.
https://youtu.be/GmRASCHJe2Q?feature=shared
Could Starship create a massive fuel-air (oxidizer) explosion? Possibly, but it seems unlikely there would be sufficient mixing before ignition to create an explosion. There would likely be an incredible fireball over a number of seconds, not an instantaneous explosion.
“Then you and the FAA would be wrong…”
You made me laugh, thanks for that. I won’t bother reading your wall of text any further.
Time will tell.
I would argue that the FTS is there to make sure the rocket doesn’t do a 180 and make a direct impact with daycare center. It does that by make sure all the propellant blows up before it gets anywhere near people on the ground. It also triggers before the rocket’s course could end up heading toward people on the ground.
Towards the end of the stage II burn, the FTS probably shouldn’t do anything more than make sure the stage won’t survive re-entry. The atmosphere will do the destruction. Just blowing a few holes in some key areas would do that, as surviving re-entry is quite an engineering task.
If the FTS could blow Starship to smithereens at the end of the Stage II burn, then Starship would be the world’s largest shotgun anti-satellite weapon because it would fill LEO with shards of metal and ceramic tiles.
At the point of FTS activation, Starship wasn’t in the Earth’s atmosphere to a significant degree, so there were no aerodynamic forces to rip it apart. So it will tumble along until it gets into thicker air. That’s is exactly what happened, so I’d say the FTS is fine.
It’s a common misconception that FTS needs to completely destroy a vehicle. Big chunks reentering uncontrolled on a ballistic trajectory is not a problem as long as you can prove the total thrust impulse cannot carry it into a populated area.
My understanding is that the nonconformance with Starship flight 1 was that the engines apparently kept firing after the FTS command was sent. Only then did it matter that the charges were not sufficient to destroy the vehicle completely. Often with multi-engine vehicles an uncontrolled engine is designed to maintain state rather than shut down. The implicit assumption is that most such cases will affect a small number of engines and the rest of the engines can compensate for thrust/mixture/vector errors. That assumption proved to be incorrect on SuperHeavy flight 1 where fires and explosions took out communications to multiple engines in quick succession. If the engines had shut off when commanded and the vehicle stayed intact until ballistic reentry, there would have been no problem. However after flight 1 it became clear that the charges needed to be designed to ensure that thrust terminates (which practically means immediate destruction of the vehicle because it’s really hard to prove engines will shut off in all conceivable fill head and acceleration regimes if the tanks remain intact).
The point about the header tank is valid but it’s a secondary issue since the impulse from the downcomers is trivial. In case you do land in a populated area you want a deflagration not a detonation. You generally want to ensure chemically reactive propellants are not confined in pressure vessels on impact. Perhaps the SS downcomers are large enough to count as a tank breach once the main tanks come apart. Or it’s possible that the engineers were able to get fatality risk below the required threshold with just trajectory design, thrust termination, and opening main tanks. The juice of preventing overpressure from header tank explosion isn’t worth the squeeze.
These are actually from last April, after the first test flight.
Hail to the victors valiant …
Got a question for the rocket knowledgeable people out there. Watching the booster clime out of the atmosphere, it seemed to me that the exhaust plume didn’t expand as much as usual for other boosters. That may have been an optical trick given that even a fuel rich exhaust wouldn’t be as sooty and visible as a kerolox exhaust. But I wondered if by having so many engines in the booster, that there might be some interesting pressure gradients for the inner engines since their exhausts are somewhat “confined” by the engines in the outer ring. Could this be a poor man’s aerospike?
Well here’s a comment from a rank amateur (I’ve only built solid-fueled Estes rockets or a few custom variants, but I did stay in a Holiday Inn Express recently).
The “point” being that the exhaust flow from SuperHeavy displays shock diamonds. That’s indicative of supersonic flow. The diamonds form as a result:
of standing wave patterns that appear in the supersonic exhaust plume of an aerospace propulsion system, such as a supersonic jet engine, rocket, ramjet, or scramjet, when it is operated in an atmosphere. The “diamonds” are actually a complex flow field made visible by abrupt changes in local density and pressure as the exhaust passes through a series of standing shock waves and expansion fans. Mach diamonds are named after Ernst Mach, the physicist who first described them.
According to that “indisputably” authoritative source Wikipedia.
The point being that you get multiple diamonds when the flow is reflected back onto itself as described further in that article:
Shock diamonds form when the supersonic exhaust from a propelling nozzle is slightly over-expanded, meaning that the static pressure of the gases exiting the nozzle is less than the ambient air pressure. The higher ambient pressure compresses the flow, and since the resulting pressure increase in the exhaust gas stream is adiabatic, a reduction in velocity causes its static temperature to be substantially increased.[2] The exhaust is generally over-expanded at low altitudes, where air pressure is higher.
As the flow exits the nozzle, ambient air pressure will compress the flow.[2] The external compression is caused by oblique shock waves inclined at an angle to the flow. The compressed flow is alternately expanded by Prandtl-Meyer expansion fans, and each “diamond” is formed by the pairing of an oblique shock with an expansion fan. When the compressed flow becomes parallel to the center line, a shock wave perpendicular to the flow forms, called a normal shock wave or Mach disk. This locates the first shock diamond, and the space between it and the nozzle is called the “zone of silence”.[3] The distance from the nozzle to the first shock diamond can be approximated by
x = 0.67D0 * Sqrt(P0 / P1)
where x is the distance, D0 is the nozzle diameter, P0 is flow pressure, and P1 is atmospheric pressure.[3]
As the exhaust passes through the normal shock wave, its temperature increases, igniting excess fuel and causing the glow that makes the shock diamonds visible.[2] The illuminated regions either appear as disks or diamonds, giving them their name.
Eventually the flow expands enough so that its pressure is again below ambient, at which point the expansion fan reflects from the contact discontinuity (the outer edge of the flow). The reflected waves, called the compression fan, cause the flow to compress.[2] If the compression fan is strong enough, another oblique shock wave will form, creating a second Mach disk and shock diamond. The pattern of disks and diamonds would repeat indefinitely if the gases were ideal and frictionless;[2] however, turbulent shear at the contact discontinuity causes the wave pattern to dissipate with distance.[4]
Unlike on Falcon 9 you wouldn’t see any extensive exhaust “plume” expansion until there are no longer any shock diamonds visible. It will of course expand some as it gains altitude but it would be very hard to judge with the eye I would think. And with a lack of water vapor etc. at high altitudes to condense out of the plume and very little to no soot, it’d be very hard to see the normal plume expansion, but when shock diamonds are present, it would tail the visible exhaust some distance from the booster.
With 33 engines contributing to that, the supersonic flow would also be somewhat chaotic based on my untrained suspicions.
This adiabatic action, reaction is taking place in the flow and not contributing thrust to the rocket so no I don’t think it would be fair to call this an aerospike.
Hope this helps and that I didn’t lead you astray. If I did, no doubt someone else will jump in to point out my gratuitous mistakes.
The Soyuz rocket uses hot staging on the second stage and it is incredibly reliable. So that certainly isn’t the problem.
I am surprised at how well this flight went considering the disaster that was the one prior. But SpaceX needs to start flying actual paying cargo sooner rather than later. Flying this thing to destruction without payload can’t be cheap.
The just need to get this to work reliably enough to deliver Starlink satellites, and progressively work on reusability just like they did with the Falcon 9.
The purpose of FTS is to unzip the tanks and release the propellants. There’s no real possibility of creating a thermobaric event (thermobaric munitions are basically dust explosions, where aerosols can be considered dust). There are only certain conditions where liquid methane will burn, much less explode. This is not true for hydrogen, interestingly enough.
FTS does not solve the real problem, of which we have many real world examples. When Columbia disintegrated over Texas, the truck sized SSMEs made it to the ground. When CRS-7 disintegrated over the Atlantic, 11 intact massive objects hit the water (ten Merlins and one Dragon capsule).
Not that long ago, an Ariane 5 launched on the wrong azimuth, which went unnoticed by the ground controllers, who never triggered the FTS, resulting in an overflight of Sao Paulo, Brazil. Now imagine…
Starship launches, and 30 seconds in rolls to the wrong azimuth and heads due north or south. The FTS fires, the fuel is harmlessly dissipated. Then 39 objects the weight of cast iron stoves rain down on Brownsville or Matamoros, accompanied by an 11 ton steel heat shield.