totm nov 2023 SpaceX Discussion Thread

[RCgothic]

47 minutes ago, Deddly said:

Sorry to continue this aside for a moment, but that doesn't add up in my admittedly tired brain. If planes are safer per mile, it should be safer to travel by plane always.

No, because if the distance is fixed at the same for each, then the plane is no longer making up for being more dangerous per trip by going further.

As Tomf mentioned earlier, the risks of flying are concentrated around landing and take off. It's not much less risky to cut down the cruise phase, which is statistically the safest bit of the flight. 

And actually, short-haul aircraft are smaller, more vulnerable to sudden cross-winds and vortex interference, undergo more frequent landing, take-off, temperature and pressure cycling, and are less well maintained on average.

Trains easily come out on top over short distances.

Edit: Although now that I'm following that logic in the opposite direction, I suppose there might be a distance over which trains become less safe. Every section of track and every set of points crossed is a potential accident. So extending the trip linearly increases the risk of a train journey, whereas a plane is safely in cruise mode.

Edited Sunday at 09:11 PM by RCgothic

[tater]

21 minutes ago, mikegarrison said:

So you are comparing things that are very unlike each other. More so than apples and oranges.

I also imagine that fatal incidents involving trains are overwhelmingly with small numbers of deaths, which is quite rare for air travel (which is astoundingly safe). The total deaths on trains maybe dominated by a few huge derailments—which are still likely more survivable than air crashes (% killed). Here in NM, I think all of the 10s of deaths caused by our "Railrunner" system (famous only from being used on Myth Busters) were pedestrians, bikes, or cars hit (usually at level crossings, though I think a drunk who passed out on the track in Bernalillo was just on the line someplace).

Not really the same at all as you say.

[Deddly]

Sorry for contributing to the off topic

1 hour ago, Minmus Taster said:

It's interesting that the offset thrust doesn't immediately send it spinning in an intuitive direction. Must be because of all that liquid fuel sloshing around

[magnemoe]

2 hours ago, Deddly said:

Sorry to continue this aside for a moment, but that doesn't add up in my admittedly tired brain. If planes are safer per mile, it should be safer to travel by plane always.

in theory you are incorrect. Short plane trips are more dangerous as main danger is takeoff and landing while trains have an pretty constant risk / kilometers traveled. 
However in practice you are correct as short plane flights mostly exist then its rarely an train option.  Yes its some exceptions like inner city airports but you don't use them to an nearby hub, you might use them for an more remote one however. 

[Nuke]

2 hours ago, Minmus Taster said:

The vibration of those engine nozzles is what catches my eye the most, I never thought of them as being flexible.

bells ring.

[GuessingEveryDay]

2 hours ago, darthgently said:

What is this camera case glazing made of?

Could also be a system of mirrors. Camera behind some THICC glass, aimed at a mirror

[magnemoe]

9 hours ago, Minmus Taster said:

Looks to me like a RUD instead of an FTS trigger. This is probably the upper half of the ship if I had to guess.

Now this is very cool, I know lots of the old Apollo ground shots was done with an 30-40 cm telescope on an radar guided mounts for Bofors 40 mm guns. Yes you want to modify it a bit as it was not designed to track supersonic targets leaving and using an transducer as you wanted to track the second stage. 
Today you could track it by the light I think, simple image processing,  probably with an manual override for staging. 

[magnemoe]

2 hours ago, RCgothic said:

No, because if the distance is fixed at the same for each, then the plane is no longer making up for being more dangerous per trip by going further.

As Tomf mentioned earlier, the risks of flying are concentrated around landing and take off. It's not much less risky to cut down the cruise phase, which is statistically the safest bit of the flight. 

And actually, short-haul aircraft are smaller, more vulnerable to sudden cross-winds and vortex interference, undergo more frequent landing, take-off, temperature and pressure cycling, and are less well maintained on average.

Trains easily come out on top over short distances.

Edit: Although now that I'm following that logic in the opposite direction, I suppose there might be a distance over which trains become less safe. Every section of track and every set of points crossed is a potential accident. So extending the trip linearly increases the risk of a train journey, whereas a plane is safely in cruise mode.

And probably an culture thing. 

Here the driver has problems looking ahead, now adding more carts would improve safety by orders of magnitude like if braking hard. it does not have to be passenger carts. 
 

[darthgently]

50 minutes ago, GuessingEveryDay said:

Could also be a system of mirrors. Camera behind some THICC glass, aimed at a mirror

I think you are correct.  That would explain the curved border that keeps bouncing around on the left.  Still, even the reflected radiant heat through the mirrors would be tough stuff.  

[Meecrob]

How's it going losers? I haven't been by in a while. You guys razzing @Exoscientist for me while I was gone?

[darthgently]

2 hours ago, Meecrob said:

How's it going losers? I haven't been by in a while. You guys razzing @Exoscientist for me while I was gone?

We mostly just watch him pwn himself these days

[darthgently]

13 hours ago, Deddly said:

Sorry for contributing to the off topic

It's interesting that the offset thrust doesn't immediately send it spinning in an intuitive direction. Must be because of all that liquid fuel sloshing around

I might be confusing props leaks for RCS but I thought I was seeing RCS trying to correct attitude.  And this might explain the active off center engines not accounting for the reconstructed rotation entirely

[Exoscientist]

On 3/8/2025 at 1:37 PM, camacju said:

ah yes the space shuttle

famous for being privately developed and also never killing any astronauts ever

that's the example you choose?

I'm looking forward to the ninth flight of New Armstrong later this month!

 SpaceX was spectacularly successful with the Falcon 9 by first aiming for an expendable launcher, then proceeding to reusability. If SpaceX took this approach with the Starship, they would already be flying a 250 ton capacity launcher that could make flights to the Moon and to Mars in a single launch now. Instead, they won’t let their launcher be operational until full reusability is achieved, and we don’t know when that would be. At this point SpaceX doesn’t even know what heat shield they will use for the Starship, having abandoned the one they had used on several flights.

Blue Origin is a taking the approach of getting payload to orbit first, like what was done with the Falcon 9. Landing is a secondary, even minor goal initially. They plan on proceeding to a large lunar lander this year.  Running the numbers this lander could serve to land a crew module at 3 tons mass on the Moon and could be launched on an expendable New Glenn or Falcon Heavy at a 60 tons to LEO capacity in a single launch.  No multi-billion SLS, no refueling flights required.

  Bob Clark

[tater]

 

 

[Flavio hc16]

24 minutes ago, Exoscientist said:

 SpaceX was spectacularly successful with the Falcon 9 by first aiming for an expendable launcher, then proceeding to reusability. If SpaceX took this approach with the Starship, they would already be flying a 250 ton capacity launcher that could make flights to the Moon and to Mars in a single launch now. Instead, they won’t let their launcher be operational until full reusability is achieved, and we don’t know when that would be. At this point SpaceX doesn’t even know what heat shield they will use for the Starship, having abandoned the one they had used on several flights.

Blue Origin is a taking the approach of getting payload to orbit first, like what was done with the Falcon 9. Landing is a secondary, even minor goal initially. They plan on proceeding to a large lunar lander this year.  Running the numbers this lander could serve to land a crew module at 3 tons mass on the Moon and could be launched on an expendable New Glenn or Falcon Heavy at a 60 tons to LEO capacity in a single launch.  No multi-billion SLS, no refueling flights required.

  Bob Clark

I'm skeptical that New Glenn will be able to launch 60 tons to LEO any time soon ( <18 months), and that this lander can land a crew on the moon with today's standard of safety.

 

You know why Spacex did develop falcon 9 and BO is developing NG the way they do instead of how spacex is testing Starship? Because the NEEDED/NEED to do so, they NEED an orbital rocket to have a businnes. Spacex is in the controlling seat right now, so they can test a rocket without payload. In the long term, Spacex method of launching starship will pay out.

[Exoscientist]

Finally, people are starting to ask the tough questions about the SpaceX development of Starship:

Twin Test Flight Explosions Show SpaceX Is No Longer Defying Gravity.
Consecutive losses of the Starship rocket suggest that the company’s engineers are not as infallible as its fans may think.
…
But these two Starship explosions were a step backward in SpaceX’s development process, as the flights could not even repeat the successes of earlier test flights, and they perhaps show that the company’s engineers are not as infallible as fans of the company sometimes like to think.
“There’s this persona that has built up around SpaceX, but you’re starting to see that they’re human, too,” said Daniel Dumbacher, a former NASA official who is now a professor of engineering practice at Purdue University and chief innovation and strategy officer for Special Aerospace Services, an engineering and manufacturing company whose customers include NASA, the United States Space Force and some of SpaceX’s competitors.
https://www.nytimes.com/2025/03/08/science/starship-spacex-explosion-elon-musk.html
(Behind paywall.)

Repeated engineering failures stem from the top. SpaceX needs a true Chief Engineer making the engineering decisions.

  Bob Clark

[Nuke]

rockets are hard. seems they corrected an attic fire but then the bell blew up. could have been their analysis of 7 was flawed and led to the correction of the wrong thing. or the problems could be unrelated. needless to day this new starship design isnt doing very well. do remember that it is a new design even though it resembles ships previously flown.

id also not rule out sabotage either, there are a lot of people mad at musk for reasons best left unmentioned.

[Ultimate Steve]

3 hours ago, Exoscientist said:

Running the numbers this lander could serve to land a crew module at 3 tons mass on the Moon

Blue Moon Mark 1 (though I am skeptical of it actually launching any time soon) is indeed intended to deliver 3 tons to the Lunar surface.

I know you are very much a flags and footprints type guy so this may not be a problem for you but the apollo LM ascent stage was 4.7 tons. It cannot get to NRHO. Unless you want to rip out Orion's service module for a new LLO capable one, you are NOT getting something with even Apollo's capability levels without either going back to 1960s safety standards or reducing the crew to 1. Also with nrho you kind of have to stay on the surface for a long duration due to orbit timings. So good luck fitting in a few weeks of life support.

[AVaughan]

11 minutes ago, Ultimate Steve said:

Also with nrho you kind of have to stay on the surface for a long duration due to orbit timings. So good luck fitting in a few weeks of life support.

Isn't the plan for a south pole landing site?  If so, then why would orbit timings mean they need long durations?  Can't they launch from the pole to the correct orbit at pretty much any time?   

[Minmus Taster]

40 minutes ago, Nuke said:

id also not rule out sabotage either, there are a lot of people mad at musk for reasons best left unmentioned.

That's certainly something worth pondering but I doubt it. It's not like you could just slap a bomb onto the things side, it would need to be something more subtle, maybe a disgruntled worker quietly creating defects? I'd imagine that you wouldn't be able to get away with even that for long though, the possibility of sabotage has surely been thought of before (I wouldn't be surprised if people started claiming sabotage regardless of whether there's evidence for it, divisive times and all that stuff). Although you'd think a saboteur with a political motivation would make their manifesto known at some point, clearly they would be intelligent enough to know that their current actions are barely putting a dent in such a large company. Ultimately it's still just speculation though, get back to us on the 6th failed launch.

[RCgothic]

20 minutes ago, AVaughan said:

Isn't the plan for a south pole landing site?  If so, then why would orbit timings mean they need long durations?  Can't they launch from the pole to the correct orbit at pretty much any time?   

Inclination is only one part of the equation. With long-period orbits like NRHO correcting the phase angle to achieve a rendezvous without an unreasonable starting DV can then take weeks.

[darthgently]

3 hours ago, Ultimate Steve said:

Also with nrho you kind of have to stay on the surface for a long duration due to orbit timings. So good luck fitting in a few weeks of life support.

I don’t see how NRHO will remain the only lunar launch to rendezvous target.  Seems like we will want at least a secondary (unmanned ?) station in a faster circular polar orbit in the same plane as NRHO that would have additional emergency life support and medical supplies, perhaps some emergency delta-v in the form of long shelf life small SRB+Ion/PV stages that can be docked to and utilized after accidental loss of main props or similar.   So no waiting for Gateway to tiptoe down from apoapsis; rather launch to rendezvous with the faster orbiting emergency station fast and head back to LEO in the case of a medical emergency, for example.

[RCgothic]

I went and looked it up. NRHO isn't *that* long a period, at about 6.5 days. So your nominal stay is at least that long, generally multiples thereof.

Then the worst case abort is 4 days depending on orbiting element phasing.

So the lander needs at least a week's endurance, or more likely 2 weeks.

That's a lot more than the Apollo LM.

Ref:

https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2018_AAS_WhiDavBurMcCPowMcGHow.pdf

[tater]

30 minutes ago, RCgothic said:

I went and looked it up. NRHO isn't *that* long a period, at about 6.5 days. So your nominal stay is at least that long, generally multiples thereof.

Then the worst case abort is 4 days depending on orbiting element phasing.

So the lander needs at least a week's endurance, or more likely 2 weeks.

That's a lot more than the Apollo LM.

Ref:

https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2018_AAS_WhiDavBurMcCPowMcGHow.pdf

Yeah, everything about Gateway is garbage that is forced by the useless capability of SLS/Orion.

[magnemoe]

7 hours ago, Exoscientist said:

 SpaceX was spectacularly successful with the Falcon 9 by first aiming for an expendable launcher, then proceeding to reusability. If SpaceX took this approach with the Starship, they would already be flying a 250 ton capacity launcher that could make flights to the Moon and to Mars in a single launch now. Instead, they won’t let their launcher be operational until full reusability is achieved, and we don’t know when that would be. At this point SpaceX doesn’t even know what heat shield they will use for the Starship, having abandoned the one they had used on several flights.

Blue Origin is a taking the approach of getting payload to orbit first, like what was done with the Falcon 9. Landing is a secondary, even minor goal initially. They plan on proceeding to a large lunar lander this year.  Running the numbers this lander could serve to land a crew module at 3 tons mass on the Moon and could be launched on an expendable New Glenn or Falcon Heavy at a 60 tons to LEO capacity in a single launch.  No multi-billion SLS, no refueling flights required.

  Bob Clark

 SpaceX was spectacularly lucky with the Falcon 9 design, having lots of engines, this was pretty rare for liquid fueled engines outside the N1, note that many Soviet engines has multiple nozzles for an turbo pump. 
They was lucky again as they designed the merlin to be reusable so they could do lots of test burns.
Finally they could use the discarded first stages to train for recovery, the cost was just the added hardware for this tests. 
SpaceX is still the only company who reuses their first stage but this will change soon.
But all the others copies falcon 9 first stage, SpaceX just level up first. 

Now an disposable second stage would make sense if launching starlinks was an priority but its unlikely you would avoid the ship v2 problems. You would probably get more fails as the fuel line design would be the same.