The Starship "I risk sending a thread off topic" Homeless Posts Thread 2

[robot_enthusiast]

I'm surprised there doesn't appear to have been any discussion about the giant crane they're starting to assemble.  I think it was Mary who said once that a friend of hers was going to Boca Chica to build something and "wait until you see the size of the crane we're bringing with us".  It would appear to be even larger than the previous "BlueZilla".

It's been discussed, mainly across in the SpaceX Facilities and Fleets section.

https://forum.nasaspaceflight.com/index.php?board=80.0

It is probably there to assemble the launch tower, but it might also be able to lift an empty Starship on top of a SuperHeavy on the launch mount. I'm not good at reading load charts though.

I don't know how to read a load chart either, but the video you responded to shows a 380 tonne object being lifted to a hook height of 140m, so theoretically a Starship with a full payload is within its capacity to place on top of a Superheavy.

[xvel]

Starship when stacking needs to be stabilized, so no stacking before tower, stabilizing huge soda can at that height with other cranes or something is too much hassle most likely.

[AC in NC]

Starship when stacking needs to be stabilized, so no stacking before tower, stabilizing huge soda can at that height with other cranes or something is too much hassle most likely.

I'm not sure it's as certain as that

[Lumina]

Let's assume that one possible end-of-life plan for a LSS is to turn it into a fixed structure on the surface of the Moon, putting its habitable space and storage tanks to good use for a fledgling base. If this fixed-structure LSS could be indefinitely resupplied with consumables from ISRU (e.g. say there is carbon in volatiles trapped in PSR's, and plenty of external power, etc.) how long might it remain serviceable? Any informed thoughts / guesses?

[schuttle89]

Starship when stacking needs to be stabilized, so no stacking before tower, stabilizing huge soda can at that height with other cranes or something is too much hassle most likely.

I'm not sure it's as certain as that

I wouldn't say it's certain but I'm pretty sure Elon tweeted that they wanted or needed the tower for the orbital attempt.

[Lampyridae]

Let's assume that one possible end-of-life plan for a LSS is to turn it into a fixed structure on the surface of the Moon, putting its habitable space and storage tanks to good use for a fledgling base. If this fixed-structure LSS could be indefinitely resupplied with consumables from ISRU (e.g. say there is carbon in volatiles trapped in PSR's, and plenty of external power, etc.) how long might it remain serviceable? Any informed thoughts / guesses?

In the soon-to-be bygone days when tin cans with air in space were rare and expensive, I'd say reusing the Starship as a base was great idea. But this is the We Can Launch It For You Wholesale era of space travel, where you buy all-you-can-loft services from a shady South African in Texas.

[steveleach]

Starship when stacking needs to be stabilized, so no stacking before tower, stabilizing huge soda can at that height with other cranes or something is too much hassle most likely.

I'm not sure it's as certain as that

I wouldn't say it's certain but I'm pretty sure Elon tweeted that they wanted or needed the tower for the orbital attempt.

Elon Musk, Twitter, 18 Mar 2021....

We will need launch tower for that. Hook height for the lift is ~140 m & both booster & ship need to be stabilized at stage separation joint.

[KBK]

I'm surprised there doesn't appear to have been any discussion about the giant crane they're starting to assemble.  I think it was Mary who said once that a friend of hers was going to Boca Chica to build something and "wait until you see the size of the crane we're bringing with us".  It would appear to be even larger than the previous "BlueZilla".

"Big Red" is probably the right name for it. Or maybe "Lifty McCraneFace"

[Skyway]

And this isn't even the biggest mobile crane on the market. Insane.

[Cheapchips]

Seeing the Starship derived GSE tanks going up at the launch site made me think "you could land those on Mars". 

I know it's been touch upon before, but can't help but think some of the first Starships will be cargo versions modified for GSE.  Either extended tanks or ISRU plant gear preinstalled at top.  Just needs hooking up to the broader base plumbing and 'power plant'.

Shame that trying to land them with 4 meters of each other is probably asking a bit much...

Really enjoying that while you can't play Lego with rockets, you can play Lego with Starships.

[spacenut]

More thoughts and questions on the LSS.  How much mass would it be to add SEP + aerocapture to bring the LSS back to LEO for refueling and resupply? 

Can it be refueled in LEO, fly to the Artemis orbit, pick up the astronauts, land on the moon, fly back to the Artemis station, then fly back to LEO for another round trip, without landing on earth with the fins, heat shield, etc.  It could take it's time, even if months, to return to LEO.  Multiple LSS's could be built to keep up with the pace NASA wants to pursue. 

[rakaydos]

More thoughts and questions on the LSS.  How much mass would it be to add SEP + aerocapture to bring the LSS back to LEO for refueling and resupply? 

Can it be refueled in LEO, fly to the Artemis orbit, pick up the astronauts, land on the moon, fly back to the Artemis station, then fly back to LEO for another round trip, without landing on earth with the fins, heat shield, etc.  It could take it's time, even if months, to return to LEO.  Multiple LSS's could be built to keep up with the pace NASA wants to pursue.

Hard.

Aerocapture is either easy or hard, depending on how much of a hurry you're in, because the lunar starship lacks the brakerons that not only extend the starship's braking area, they also balance the starship's CoP to allow it to brake using the belly in the first place- a lunar starship is basically limited to aerobraking tail first unless the payload is loaded EXACTLY right. This has knock on effects as all the heat is concentrated in the engine bay, limiting the usefullness of Starship's hot structure approach... it's still possible, but it'll be SLOW, and making it any faster will be a major undertaking.

SEP has dry mass problems in this application. Typically SEP craft seem like something like 50% solar panel by mass, which is a LOT of solar panels for a fueled starship. That's not even counting the additional working fluid (argon?).

[Norm38]

I still don't know what the nosecone test structure is for.  I WAS thinking that it was to give to NASA, and the structure would let them tip and roll it while people were inside, to simulate zero g, let them clamber about and get to all areas and plan out the crew arrangements.

But now they're rolling it out to the pad.  To do what?  It doesn't have any RCS or landing thrusters to test.  And if those were to be installed, wouldn't they do that on the factory side?

[livingjw]

I still don't know what the nosecone test structure is for.  I WAS thinking that it was to give to NASA, and the structure would let them tip and roll it while people were inside, to simulate zero g, let them clamber about and get to all areas and plan out the crew arrangements.

But now they're rolling it out to the pad.  To do what?  It doesn't have any RCS or landing thrusters to test.  And if those were to be installed, wouldn't they do that on the factory side?

To test structural integrity under flight loads while pressurized.

John

[Norm38]

To test structural integrity under flight loads while pressurized.

John

The nosecone isn't tankage, doesn't need to go to 6 bar.  So they would press to ~30psi, to show it can hold ~15psi in vacuum?  Or something else?

And the bracing is to push down on the nose for a MaxQ flight load?

[livingjw]

To test structural integrity under flight loads while pressurized.

John

The nosecone isn't tankage, doesn't need to go to 6 bar.  So they would press to ~30psi, to show it can hold ~15psi in vacuum?  Or something else?

And the bracing is to push down on the nose for a MaxQ flight load?

Probably test the nose cone under flight loads both pressurized and unpressurized. Cargo version will be unpressurized.

John

[edzieba]

Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

Or more out there: stick a 'drop tank' between Starship and Super Heavy that is nothing more than a pair of propellant tanks and two feed passthroughs. Use this to increase Super Heavy effective tank capacity (without draining Starship), then discard it at staging. Losing a tonne or two of stainless sheet and some short plumbing runs may be worth the extra capability for extreme loads that would otherwise be marginal for Super Heavy recovery.

[rakaydos]

Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

Or more out there: stick a 'drop tank' between Starship and Super Heavy that is nothing more than a pair of propellant tanks and two feed passthroughs. Use this to increase Super Heavy effective tank capacity (without draining Starship), then discard it at staging. Losing a tonne or two of stainless sheet and some short plumbing runs may be worth the extra capability for extreme loads that would otherwise be marginal for Super Heavy recovery.

I have suggested something similar in various "Can Superheavy SSTO without starship, and why would you want to" type threads- draining fuel from a "drop tank" starship, then "in flight abort" it off superheavy so superheavy can reach orbit.

Alas, concensus was that the fuel lines intended to load a starship in 20 minutes with fuel for 6 raptors for 5 minutes, cannot keep up with the fuel required  for 28 raptors at once.

[schuttle89]

Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

Or more out there: stick a 'drop tank' between Starship and Super Heavy that is nothing more than a pair of propellant tanks and two feed passthroughs. Use this to increase Super Heavy effective tank capacity (without draining Starship), then discard it at staging. Losing a tonne or two of stainless sheet and some short plumbing runs may be worth the extra capability for extreme loads that would otherwise be marginal for Super Heavy recovery.

I have suggested something similar in various "Can Superheavy SSTO without starship, and why would you want to" type threads- draining fuel from a "drop tank" starship, then "in flight abort" it off superheavy so superheavy can reach orbit.

Alas, concensus was that the fuel lines intended to load a starship in 20 minutes with fuel for 6 raptors for 5 minutes, cannot keep up with the fuel required  for 28 raptors at once.

The other thing is there is already margin left in super heavy for the landing burn so unless you *could* get it to orbit with that technique then not much is being accomplished. Also I could be wrong but once you're in orbit from my understanding there is not that much value to having huge amounts of thrust at the expense of having lower isp sea level engines. In other words, starship is a much more efficient way to send things deeper into space than super heavy with the exception of having more tank space which might be able to be solved with some kind of booster stage that I've seen proposed many times in different threads here.

[rakaydos]

Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

Or more out there: stick a 'drop tank' between Starship and Super Heavy that is nothing more than a pair of propellant tanks and two feed passthroughs. Use this to increase Super Heavy effective tank capacity (without draining Starship), then discard it at staging. Losing a tonne or two of stainless sheet and some short plumbing runs may be worth the extra capability for extreme loads that would otherwise be marginal for Super Heavy recovery.

I have suggested something similar in various "Can Superheavy SSTO without starship, and why would you want to" type threads- draining fuel from a "drop tank" starship, then "in flight abort" it off superheavy so superheavy can reach orbit.

Alas, concensus was that the fuel lines intended to load a starship in 20 minutes with fuel for 6 raptors for 5 minutes, cannot keep up with the fuel required  for 28 raptors at once.

The other thing is there is already margin left in super heavy for the landing burn so unless you *could* get it to orbit with that technique then not much is being accomplished. Also I could be wrong but once you're in orbit from my understanding there is not that much value to having huge amounts of thrust at the expense of having lower isp sea level engines. In other words, starship is a much more efficient way to send things deeper into space than super heavy with the exception of having more tank space which might be able to be solved with some kind of booster stage that I've seen proposed many times in different threads here.

There's a few places Superheavy might be useful- a Venus cloud city, for instance, or maybe Titan surface to near-saturn escape (that wont need 28 raptors, but it is MaxQ limited at first.)