totm nov 2023 SpaceX Discussion Thread

[darthgently]

56 minutes ago, tater said:

I don't think it's anything loony, it was likely a plumbing problem

Likely, but I bet that the actual investigation goes beyond just engineering and manufacturing issues and will also take possible security aspects into account.  As it should be.

There have been two other bomb threats at Boca Chica over the years that I just learned about and the FBI is still investigating all three of them, apparently.

Loonies do loony things

[Superpluto126]

I think its safe to say that Flight 8 Catch is off

[darthgently]

Just now, Superpluto126 said:

I think its safe to say that Flight 8 Catch is off

Catch went fine other than engine out on boost back. 

[Minmus Taster]

41 minutes ago, Ultimate Steve said:

 

Yeah right, no way the FAA isn't clamping down after this, unless Elon's "friends" (lets keep this apolitical as possible) step in which I suppose is possible.

[Superpluto126]

3 minutes ago, darthgently said:

Catch went fine other than engine out on boost back. 

Talking about the Ship Catch

[Minmus Taster]

6 minutes ago, darthgently said:

Catch went fine other than engine out on boost back. 

I think they mean a ship catch attempt

This is actually quite frightening, this could have been ugly.

Edited 5 hours ago by Minmus Taster

[JoeSchmuckatelli]

 

SX has a working very large 1st stage.  Three successful launches with two RTLS catches.  They could commercialize Booster. 

Question is - how much is the cost of expendable second stages?  Like, cool factor aside, is Starship actually necessary? 

Can we get a lot more weight to the moon and Mars now using traditional-style upper and payload staging ideas matched to the size Booster now allows? 

Or do we really need Starship to work, too? 

(is it a nice to have or a need to have?) 

[Minmus Taster]

2 minutes ago, JoeSchmuckatelli said:

 

SX has a working very large 1st stage.  Three successful launches with two RTLS catches.  They could commercialize Booster. 

Question is - how much is the cost of expendable second stages?  Like, cool factor aside, is Starship actually necessary? 

Can we get a lot more weight to the moon and Mars now using traditional-style upper and payload staging ideas matched to the size Booster now allows? 

Or do we really need Starship to work, too? 

(is it a nice to have or a need to have?) 

Been pondering this to, but Starship's primary focus will probably end up being Earth orbit and quick turnarounds and reusing hardware are essential to dominate the market with such a large vehicle.

 

[tater]

28 minutes ago, Minmus Taster said:

Yeah right, no way the FAA isn't clamping down after this, unless Elon's "friends" (lets keep this apolitical as possible) step in which I suppose is possible.

They have no need to "clamp down," the point of a mishap/anomaly investigation is to establish cause, and subsequent changes to mitigate. As has happened with other investigations, since the FAA is not in fact qualified to do much of either of those things for spacecraft, SpaceX will in fact drive the efforts. Present the problems observed, causes, and planned mitigations. They already seem to have the cause.

29 minutes ago, Minmus Taster said:

This is actually quite frightening, this could have been ugly.

That debris was no where near that aircraft, and given it burning from heating, it was way above any air traffic—presumably ATC diverts aircraft away from the flight path of the debris, which in this case would be some miles east of the fireballs.

29 minutes ago, JoeSchmuckatelli said:

Like, cool factor aside, is Starship actually necessary? 

Yea, they could throw a fairing on it, expend upper stages, and use it for Starlinks now I wager. There are probably some payloads for customers where this might be a thing as well. It's not what they want, however, and there's no real commercial reason past Starlink to bother—it's not about making money.

27 minutes ago, Minmus Taster said:

Been pondering this to, but Starship's primary focus will probably end up being Earth orbit and quick turnarounds and reusing hardware are essential to dominate the market with such a large vehicle.

The market is chump change. Starship has nothing at all to do with that aside from Starlink. Starlink alone has the potential to grossly exceed the revenue in the TAM (total addressable market) for launches. That's at most some lowball billions (10? 20?) even capturing all of it.

[Spaceception]

43 minutes ago, JoeSchmuckatelli said:

is Starship actually necessary? 

Yes. Full reuse is the name of the game, not back pedaling to partial reuse. And from the sound of it, this failure wasn't caused by anything in the vehicle contributing to reusability, so whether or not SpaceX wanted to expend it, this failure probably would've happened.

Starship is more expensive than Falcon 9's upper stage, and the cost floor will be higher if they have to build a new one each flight, limiting commercial opportunities beyond Starlink, while also lowering the potential flight rate.

I also believe that HLS benefits more from full reuse than without. In theory, you can refuel with expendable tankers, but it will take longer, and cost more. Plus, HLS will be closer to the intended version of Starship anyway, so it's good to commit to reuse for the entire architecture, rather than a bespoke lander.

SpaceX shouldn't put full reusability on the backburner, they had to retrofit it onto Falcon 9, and while they made some huge strides, it's ultimately constrained by its original design choices. Starship is still experimental, and they've had 3 mostly successful reentries so far. The Starship catch was supposed to be shortly after this flight (I'm not expecting it until flight 9 or 10 now though), but still, they are trying to make quick strides to recover the entire vehicle. They shouldn't stop when they're this close because of an unexpected failure.

[Ultimate Steve]

Interesting tangent:

Starship seemed to carry on just fine with this engine configuration for several seconds (Still accelerating enough to probably not be spinning) before ultimately failing. This surprised me as I was under the impression that Starship (the upper stage) had minimal to no engine out capability. I don't have perfect numbers, but I did shove my numbers into a spreadsheet and I came up with the following:

Assuming my numbers are right, immediately throttling the two Raptor vacuum engines down to minimum and gimbaling to the limit of 10 degrees might be enough to cancel out the torque from the uneven engine distributions in this vehicle configuration.

On the surface the math says if the CoM is more than ~21.9m from the base of the vehicle it should be stable, but the propellant will slosh towards the side of the vehicle with the engines in this case, which causes all three engines to produce less "vertical torque" and would beneficially reduce this number, by how much I am unsure. 

Admittedly my source is just some guy on Discord, but I'm told that Raptor can normally gimbal to 15 degrees, but that the current engine shielding limits that to 10 or 11 degrees. Interestingly, for future ships using Raptor 3, the full 15 degrees would be available and this puts the minimum CoM height at only about 15.8m, though future versions of the ship may have to limit their gimbals to avoid hitting the vacuum engine bells.

I don't know if the resulting thrust (of roughly 30% of normal thrust) (though if the CoM is higher than the minimum you can throttle the Vactors up more than 40%) would be enough to get into orbit for any situation aside from very late in the upper stage burn, but I find it very interesting that Starship can (at least theoretically) survive under some conditions with only 3 engines running, all on the same side of the vehicle, only one of which can gimbal.

Assuming I did my math right, of course, it has been a while since I took statics.

Edited 4 hours ago by Ultimate Steve

[Hotel26]

1. As long as engines don't RUD, their reliability seems analogous to the widepsread use these days of SD memory, which is always degrading but error-corrected.  It's overall system performance/economics that count.
2. I expect that the economics of the current state of the art (making it perfect immediately) compared to the economics of simply reserving some flight lane bandwidth (time and space) for the benefit of human progress in space flight (e.g. SpaceX) is going to argue that it will or should be the FAA/DOT that takes compensatory future action to prevent  reoccurrence of mutual hazard.  (You could actually say it is the fault of those controlling authorities, but what matters is only how those now react to the data.)  This situation is analagous to the shootdown of MH17 over the Ukraine (Donbas) in 2014.  The (impossibly) idealistic solution might have been proposed of stopping that war (still continuing (and looking mighty like ww3 already in progress, summing all told around the world)) but the actual solution applied was to ban commercial overflights of the area until such time as deemed safe to resume.

Edited 3 hours ago by Hotel26

[tater]

That map I showed was some guy's guestimate of debris, SpaceX apparently has a different view:

Quote

Following stage separation, the Starship upper stage successfully lit all six Raptor engines and performed its ascent burn to space. Prior to the burn’s completion, telemetry was lost with the vehicle after approximately eight and a half minutes of flight. Initial data indicates a fire developed in the aft section of the ship, leading to a rapid unscheduled disassembly.

Starship flew within its designated launch corridor – as all U.S. launches do to safeguard the public both on the ground, on water and in the air. Any surviving pieces of debris would have fallen into the designated hazard area. If you believe you have identified a piece of debris, please do not attempt to handle or retrieve the debris directly. Instead, please contact your local authorities or the SpaceX Debris Hotline at 1-866-623-0234 or at [email protected].

 

[Nuke]

2 hours ago, Minmus Taster said:

Yeah right, no way the FAA isn't clamping down after this, unless Elon's "friends" (lets keep this apolitical as possible) step in which I suppose is possible.

i think they may be concerned with the dogepocalypse that threatens to eat bureaucrats alive, with heel dragers and boat rockers being the juiciest prey. however the faa are one of the few three letter agencies that actually do a useful job. they will want the usual analysis and mitigation write-up before they grant the next license. that may take a little while to complete, but i dont see it as a major obstacle. spacex want to make reusable launch vehicles, not expensive fireworks.

[Nuke]

2 hours ago, JoeSchmuckatelli said:

 

SX has a working very large 1st stage.  Three successful launches with two RTLS catches.  They could commercialize Booster. 

Question is - how much is the cost of expendable second stages?  Like, cool factor aside, is Starship actually necessary? 

Can we get a lot more weight to the moon and Mars now using traditional-style upper and payload staging ideas matched to the size Booster now allows? 

Or do we really need Starship to work, too? 

(is it a nice to have or a need to have?) 

the booster has proven to be reliable, with the catch failure of the previous launch more being a tower issue. workaround for that is to have a spare tower or two in case the first one takes damage during launch. they could pivot to a disposable second stage, but the only fundamental difference between landing the first stage and the second is re-entry, and this was not a re-entry failure. it seems like a kneejerk reaction to abandon the concept when the thing that failed is something they have done right in many other launches. what were seeing here is the growing pains of moving to a new ss design.