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I'm not a 100% sure I remember this correctly (well, actually not even 90%), but the difference in timing of the two boosters might only seem more pronounced this time, because they accidentally showed footage from the same booster on one of the previous occasions. The external footage of the two boosters coming down didn't seem much different from earlier flights.

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1 hour ago, Piscator said:

The external footage of the two boosters coming down didn't seem much different from earlier flights.

It seemed very different to me. The ground tracking cam showed the entry burn on one booster starting at approximately the same time the other started, and the landing burn of one was visible from the other.

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24 minutes ago, JoeSchmuckatelli said:
28 minutes ago, sevenperforce said:

I wonder if the entire 3,750 kg payload is being placed into GEO or if parts of it broke off in transit (in LEO or GTO).

On 10/31/2022 at 6:30 PM, tater said:

 

 

 

From that article it looks like everything went to GEO together.

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Some new info from the article, in addition to what was said during the conference:
- the 7 raptors per week target was hit a quarter ago
- the second Starship launch NASA is tracking after the maiden one features a tank-to-tank propellant transfer inside a single starship
- the third Starship launch NASA is tracking features a ship-to-ship propellant transfer, to mimic a tanker/depot mission
- the fourth and last launch NASA is tracking features a long duration flight, mimicking the duration of the HLS in-space time
- the HLS demo mission on the moon, targeting Q4 2024 (i.e. 2025) but dependant on the other flights listed above, will return to lunar orbit after the completion of the landing and the associated tests. This was quite likely, but not yet 100% sure because NASA didn't include it in the HLS demo flight objectives

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4 minutes ago, Beccab said:

the second Starship launch NASA is tracking after the maiden one features a tank-to-tank propellant transfer inside a single starship

Oh, that's smart. They'll still be able to utilize a low-level continuous settling burn to effect the transfer.

Unclear, however, how a settling burn will operate if they are docking side-to-side now instead of tail-to-tail.

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2 minutes ago, sevenperforce said:

Oh, that's smart. They'll still be able to utilize a low-level continuous settling burn to effect the transfer.

Unclear, however, how a settling burn will operate if they are docking side-to-side now instead of tail-to-tail.

I assume that having both ships translate towards the same direction at the same time would work even side by side, though throttled to take into account the different mass of the two spacecrafts.

Either that or they dock side by side and only one of them translates laterally, but going forward or backwards seems less complex

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On 11/2/2022 at 11:52 AM, Beccab said:

I assume that having both ships translate towards the same direction at the same time would work even side by side, though throttled to take into account the different mass of the two spacecrafts.

Either that or they dock side by side and only one of them translates laterally, but going forward or backwards seems less complex

I think it depends to some degree on the internal plumbing, no?

If I recall correctly, this is the propellant fill adapter that the Quick Disconnect arm interfaces with, right?

fill.png

According to the renders I've seen, the fill lines run up the inside of the skirt and go directly into the methane downcomer and the LOX tank, respectively:

fill.png

So if you were to connect two starships back-to-back (which I will call "Thing 1" for no reason whatsoever), open all the valves between these fill lines, and start your settling/prop-transfer burn, the tanker can only fill the depot (or other recipient ship) until the levels are equal. On the other hand, if you connect the ships with one inverted (we'll call this "Thing 2" for absolutely no reason again) then you can transfer as much as you want:

fill.png

The other possibility would be to have some sort of positive displacement pump involved so that the "Thing 1" position could work. This would require an entire new system. However, it might be necessary if the "spray it into the empty portion of the tank" approach in the "Thing 2" position would create too much evaporation.

Edited by sevenperforce
Edits of redactions of edits
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On 11/2/2022 at 1:38 PM, sevenperforce said:

You forget that the tanks are pressurized, if pressure is larger in the tanker than target fuel will flow, you want some trust for settling but you are not afraid of bubbles other than it reduce the pressure difference. Benefit of [SNIP1] is that you could have two docking ports for added rigidity, it will be some torque as the center of mass is shifting. 

Edited by Gargamel
Quote and Portions Redacted by Moderator
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On 11/2/2022 at 2:09 PM, magnemoe said:

You forget that the tanks are pressurized, if pressure is larger in the tanker than target fuel will flow, you want some trust for settling but you are not afraid of bubbles other than it reduce the pressure difference. Benefit of [Thing 1] is that you could have two docking ports for added rigidity, it will be some torque as the center of mass is shifting. 

Ah, yes, you're absolutely right. A little thrust to provide consistent settling, and then the recipient Starship can vent to lower its tank pressure and thus accept flow from the donor Starship.

Depending on the viscosity of liquid methane and liquid oxygen, the constant settling might not even be necessary; once it gets flowing it should stay settled and the tank pressure differential will do the rest.

Edited by sevenperforce
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1 hour ago, sevenperforce said:

Ah, yes, you're absolutely right. A little thrust to provide consistent settling, and then the recipient Starship can vent to lower its tank pressure and thus accept flow from the donor Starship.

Depending on the viscosity of liquid methane and liquid oxygen, the constant settling might not even be necessary; once it gets flowing it should stay settled and the tank pressure differential will do the rest.

The venting from the recipient tank could easily provide the thrust needed for settling the propellants. Exquisitely simple, like the Soyuz boosters venting oxygen to provide separation thrust…

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2 minutes ago, StrandedonEarth said:

The venting from the recipient tank could easily provide the thrust needed for settling the propellants. Exquisitely simple, like the Soyuz boosters venting oxygen to provide separation thrust…

Yes, but that would cause rotation around the pitch axis because you'd only be venting from one of the vehicles and so you'd have off-axis thrust.

OTOH, I wonder if an alternative way to settle the propellants would be to get them rotating together in a penguin roll. Would the centrifugal force then assist in settling the propellant? Hard to know, I think...lots of CoM shifting going on.

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