totm nov 2023 SpaceX Discussion Thread

[StrandedonEarth]

The on-again, off-again Port-of-LA manufacturing facility is off again...

https://www.latimes.com/business/story/2020-06-08/spacex-exits-port-of-la-lease-again

[Nightside]

5 hours ago, tater said:

 

 

 

 

Starship: world’s first rocket designed by twitter responses.

3 hours ago, StrandedonEarth said:

The on-again, off-again Port-of-LA manufacturing facility is off again...

https://www.latimes.com/business/story/2020-06-08/spacex-exits-port-of-la-lease-again

Maybe it was a bargaining chip to get more money from Texas.

[tater]

LOL

 

[kerbiloid]

Quote

20km hops with the belly flop

A new spaceship class is going to be born: a hoppah-floppah.

Edited June 9, 2020 by kerbiloid

[tater]

 

 

[RealKerbal3x]

11 hours ago, tater said:

 

 

Interesting, the legs are being redesigned again. I still think they should be more like Falcon 9 legs - those wouldn't be too hard to integrate into the engine skirt.

Or perhaps, similarly, something like what the Hercules lander was meant to have:

Also, more progress in Boca Chica:

 

[magnemoe]

1 hour ago, RealKerbal3x said:

Interesting, the legs are being redesigned again. I still think they should be more like Falcon 9 legs - those wouldn't be too hard to integrate into the engine skirt.

Or perhaps, similarly, something like what the Hercules lander was meant to have:

 

 

I liked the Hercules design more so in that it looks like you could integrate it with the heat shield. as in the shield cover the legs then retracted. 
Starship legs would be smaller compared with this lander as you are limited to the skirt length, you want the upper hinge at the top of skirt who is an strong point. Still this is 3-4 meters so you almost double the footprint. 

[Hannu2]

On 6/7/2020 at 11:17 PM, RealKerbal3x said:

I'm still sceptical that SpaceX can get a cargo Starship to Mars by 2022, but we'll have to see. I think crew may be the limiting factor - it may take several more years for the crew variant to become reliable enough for it to be certified for crew. Without an abort system, it needs to be approaching airliner-like reliability. And I'm not sure they can do that in four years.

Those Mars schedules are extremely overoptimistic. Or given in Musk -time, which is about an order of magnitude slower than SI units.

In real world it would be good work if they can launch first commercial satellites to orbit in 2022. To be honest there is quite huge step from simple hoppers to orbital class vehicle and it seems that development does not go as intended. If they have an anomaly with later orbital capable vehicle it takes easily more than half year to just make paperworks with authorities before they can continue experiments.

After that it takes several years to get man rating to LEO. And probably more to get license to land crew on Moon.

[magnemoe]

23 minutes ago, Hannu2 said:

Those Mars schedules are extremely overoptimistic. Or given in Musk -time, which is about an order of magnitude slower than SI units.

In real world it would be good work if they can launch first commercial satellites to orbit in 2022. To be honest there is quite huge step from simple hoppers to orbital class vehicle and it seems that development does not go as intended. If they have an anomaly with later orbital capable vehicle it takes easily more than half year to just make paperworks with authorities before they can continue experiments.

After that it takes several years to get man rating to LEO. And probably more to get license to land crew on Moon.

Commercial in 2022, pretty plausible if you include starlink. Other payloads a bit doubtfully. 
Don't see an orbital fail generating much more issues than the stage crashing and blowing up tanks they have been doing the last years. Now if they carry other stuff than starlink and its an pad failure or accent issue then yes. 

Manned I see as much farther away, they might well have it qualified for orbit pretty fast even lunar orbit but that is as an space station not as an human rated launcher. 
Even moon landings is probably simpler as its less stressed. 

[tater]

1 hour ago, Hannu2 said:

Those Mars schedules are extremely overoptimistic. Or given in Musk -time, which is about an order of magnitude slower than SI units.

Musk is always optimistic on "aspirational" timelines, he's said so, and why. He wants things to happen in perceivable timeframes. If he followed NASA dev spreadsheet timelines, they would have already spent several billion dollars on F9 booster landing—and it would not have happened yet.

SS is moving pretty fast, frankly, and the focus is on infrastructure... his focus on Mars is admirable, if kooky, because he talks about building a shipyard. As if they need 1000 Starships. Fine by me.

1 hour ago, Hannu2 said:

In real world it would be good work if they can launch first commercial satellites to orbit in 2022.

Yeah, it will be amazing if they get it flying that soon considering how transformational this vehicle is.

 

1 hour ago, Hannu2 said:

To be honest there is quite huge step from simple hoppers to orbital class vehicle and it seems that development does not go as intended.

Musk seems to think designing the baseline vehicle is not hard, it's building them in a cost effective way. The long pole is not getting to orbit, I think they will do that, and closer to their stated timeline. EDL from orbit? Yeah, that will be a difficult issue.

1 hour ago, Hannu2 said:

If they have an anomaly with later orbital capable vehicle it takes easily more than half year to just make paperworks with authorities before they can continue experiments.

Huh? Who would care unless it wrecks a NASA facility?

1 hour ago, Hannu2 said:

After that it takes several years to get man rating to LEO. And probably more to get license to land crew on Moon.

Crew rating only matters for NASA. They can otherwise do whatever they like is someone is crazy enough to climb on top. For the Moon? Propulsive landing there is easier, frankly (the landing part is a solved problem, minus reentry it should be trivial).

 

[mikegarrison]

2 hours ago, tater said:

Who would care unless it wrecks a NASA facility?

The FAA might. If there are enough launches, *somebody* is going to be the regulator for them.

[tater]

36 minutes ago, mikegarrison said:

The FAA might. If there are enough launches, *somebody* is going to be the regulator for them.

True, I might amend that to say if there are enough *explosions* someone will need to regulate. The launches get NOTAMs, as long as they are't risking stuff outside the NOTAM—that's what the NOTAM is for, right?

[tater]

 

That means there might be a dense train pass 90 minutes later...

[mikegarrison]

24 minutes ago, tater said:

True, I might amend that to say if there are enough *explosions* someone will need to regulate. The launches get NOTAMs, as long as they are't risking stuff outside the NOTAM—that's what the NOTAM is for, right?

I'm actually making the bigger point that commercial space is going to be regulated if it gets big enough. In the US, likely by the FAA. Not just for interactions with airspace, but because regulating things that fly is their business (or at least, what they perceive their business to be).

[tater]

10 minutes ago, mikegarrison said:

I'm actually making the bigger point that commercial space is going to be regulated if it gets big enough. In the US, likely by the FAA. Not just for interactions with airspace, but because regulating things that fly is their business (or at least, what they perceive their business to be).

Yeah, true. They already control the process near the launch sites anyway, though, right? They have to seek permission for each flight already.

If you meant crew flights, then I think you are right once the number exceeds some number. There is some exception for safety to allow Virgin to fly their suborbital rocketplane, right? Not sure what the level would need to be to increase the safety requirement.

[mikegarrison]

13 minutes ago, tater said:

Yeah, true. They already control the process near the launch sites anyway, though, right? They have to seek permission for each flight already.

If you meant crew flights, then I think you are right once the number exceeds some number. There is some exception for safety to allow Virgin to fly their suborbital rocketplane, right? Not sure what the level would need to be to increase the safety requirement.

I'm still not sure you see what I'm getting at. I'm talking airworthiness (spaceworthiness?). The designs and the manufacturing process will have to be certified. The parts used will have to be certified. Design changes will have to be tracked and approved. Environmental laws will have to be considered. All kinds of stuff like that. NASA doesn't do this -- it's not their job. But the FAA? That is their job.

And not just for crewed rockets. The FAA regulates drone airplanes too.

Edited June 9, 2020 by mikegarrison

[tater]

23 minutes ago, mikegarrison said:

I'm still not sure you see what I'm getting at. I'm talking airworthiness (spaceworthiness?). The designs and the manufacturing process will have to be certified. The parts used will have to be certified. Design changes will have to be tracked and approved. Environmental laws will have to be considered. All kinds of stuff like that. NASA doesn't do this -- it's not their job. But the FAA? That is their job.

And not just for crewed rockets. The FAA regulates drone airplanes too.

Yeah, but so far anyway, they are already regulating the launches of SpaceX and BO (both in TX right now). They have to seek permission to launch, and submit hazard and environmental impact studies first from what I have seen. Somewhere up the thread are the PDFs of the environmental impact reports filed with the feds for both KSC and Boca Chica for Starship operations.

I can see more stringent requirements for crew vehicles, but most launch vehicles are expendable,so certification (or airworthiness) isn't a thing in some sense, they're all 1 offs, there is a high % (compared to aircraft) that they will blow up.

[sevenperforce]

19 hours ago, tater said:

Actually, the breakeven was supposed to be flying over 50 times a year, though I don;t know how many vehicles they assumed for that (that was the calc I remember seeing for Shuttle to be cost effective vs Titan for sat launch.

In a hearing before the House subcomittee on science and tech (Space Science and Applications subcommittee) in 1982, Culbertson (NASA's deputy administrator at the time) said that the planned sustained launch rate was 40 flights per year with a fleet of four to five orbiters, and up to 50 flights if demand was there. It was expected that a Shuttle orbiter would be capable of flying 8 times per year or up to 10 in extraordinary circumstances.

As we know, the program ran for 30 years with no more than four operational orbiters at any time and 135 launches, or about ten months between each flight on average. The fastest-ever turnaround was 54 days.

19 hours ago, tater said:

Yeah, right now a tank way up in the nose...

There's a LOX tank up there but no CH4. I am also unsure whether there are meth-gox accumulators or if RCS is run straight off tank head pressure. It would make sense to have some sort of separate meth-gox accumulators and pumping mechanism for on-orbit loiter.

Any cabin-based launch escape system would need an independent landing mode, which adds additional complexity.

Having that LOX tank up in the nose means extra weight if you're trying to abort, which is not helpful. A proper bipropellant liquid thruster will have much higher TWR than a meth-gox thruster, so it would make sense to design some pressure-fed mini-Raptors, particularly if you already have accumulator tanks up in the nose with you. You'd have to add a CH4 header tank, though. The high-thrust regime is only necessary for the actual abort, so those tanks can burn to depletion and then hopefully you can shutter them and use remaining pressed gas in your hot-gas thrusters to control trajectory.

Then you have to figure out whether you're using chutes for landing or what.

19 hours ago, tater said:

He is not good at this, haha.

 

[tater]

The stance of the new version has always been too narrow for rough sites, IMO. Any wider stance is an improvement.

[mikegarrison]

19 minutes ago, tater said:

Yeah, but so far anyway, they are already regulating the launches of SpaceX and BO (both in TX right now). They have to seek permission to launch, and submit hazard and environmental impact studies first from what I have seen. Somewhere up the thread are the PDFs of the environmental impact reports filed with the feds for both KSC and Boca Chica for Starship operations.

I can see more stringent requirements for crew vehicles, but most launch vehicles are expendable,so certification (or airworthiness) isn't a thing in some sense, they're all 1 offs, there is a high % (compared to aircraft) that they will blow up.

The current situation really doesn't warrant a huge amount of regulatory oversight because there just isn't enough of it going on. Nobody had to certify the Wright Flyer for airworthiness.

But if the commercial space advocates actually do what they want to to, that will change.

One-offs and development work will probably still be treated like experimental vehicles (as flight test airplanes are today), but a fleet of rockets? I expect design certification and manufacturing certification and modification certification and all that.

[tater]

10 minutes ago, mikegarrison said:

One-offs and development work will probably still be treated like experimental vehicles (as flight test airplanes are today), but a fleet of rockets? I expect design certification and manufacturing certification and modification certification and all that.

That's a good thing, particularly if they manage to work out reuse (no crew for a long time, I would think), and start treating it like/as airworthiness.

BO and Virgin both have to count on "experimental" status already, otherwise they'd have to be commercial carriers, and they'd never be allowed to fly. I suppose it's a matter of how much has to happen before regulations change—and some of the drive could come from SpaceX in this case. If it takes says/weeks to get approval for a launch, and you want to launch every day, you might ask, "What hoops do we need to jump through so we can just fly?"

[sevenperforce]

16 minutes ago, tater said:

The stance of the new version has always been too narrow for rough sites, IMO. Any wider stance is an improvement.

Agreed. I'm curious what that looks like. It's not an easy problem to solve.

In that vein, I'm still uneasy about the final flip. The fact that the ship needs all four flaperons and either engine power or thrusters to execute the flip seems like a disaster waiting to happen.

[sevenperforce]

56 minutes ago, tater said:

The stance of the new version has always been too narrow for rough sites, IMO. Any wider stance is an improvement.

I wonder if you could make a passively-stable design and just go with damn thrusters (and maybe some pumped CoM-management) all the way down. 

The best system is no system....

[RCgothic]

How big is the extended Falcon Heavy fairing? Trying to find some details but coming up empty-handed.

[RealKerbal3x]

1 hour ago, sevenperforce said:

I wonder if you could make a passively-stable design and just go with damn thrusters (and maybe some pumped CoM-management) all the way down. 

The best system is no system....

Pumping propellant around during EDL is going to require some pretty hefty pumps, and I doubt they'd fail any less easily than the flaperon actuators. If it's completely passively stable that might work, but no matter whether EDL control is active or passive, a successful landing still depends on at least two out of three engines lighting for a propulsive landing.

SpaceX is serious about landing Starship on Mars, and ultimately there's not many ways you can land a big spacecraft on Mars that aren't terrifying-looking (unless you want giant wings or an enormous parachute). Emergencies during launch could be fixed with some sort of LES but there's no such escape system for landing. They just have to make it reliable by flying it, a lot.