totm nov 2023 SpaceX Discussion Thread

[magnemoe]

1 hour ago, darthgently said:

As long as separating capsule fuel from trunk, make the trunk methalox with vacuum raptor merlin and put the heat shield back on the capsule.  So trunk is basically stage 3.

It still to get into moon orbit, dock and return after second docking with lander after spending over an week in moon orbit so I think you need hypergolic. I would start thinking about lengthening second stage at this point rather than having an short stage 3 as an stage 2 copy. Lengthening second stage would be part of crew rating FH as the only reason to do this is the moon if NASA pays for it. 
The goal would be to get 2 stage to do the moon injection burn like done on Apollo. 

[CBase]

SpaceX seems to expect to return this week to Falcon 9 launches: https://spaceflightnow.com/2024/07/16/spacex-requests-public-safety-determination-for-return-to-flight-for-its-falcon-9-rocket/

 

[tater]

 

[darthgently]

1 hour ago, tater said:

 

Would other big contractors have waited until the rain stopped?  I really don't know.  But I like that they didn't let the rain stop them 

[Flavio hc16]

oooffff size, gigantic! (again)

 

 

[Nuke]

1 hour ago, darthgently said:

Would other big contractors have waited until the rain stopped?  I really don't know.  But I like that they didn't let the rain stop them 

if we did that in southeast alaska, nothing would ever get done.

 

of course were not doing rockets. that's kodiak's gig.

Edited July 25 by Nuke

[tater]

Given the salt in the air so close to the ocean, washing it off with fresh water can only be a plus, lol.

[tater]

https://www.spacex.com/updates/

Quote

FALCON 9 RETURNS TO FLIGHT
SpaceX submitted its mishap report to the Federal Aviation Administration (FAA) regarding Falcon 9’s launch anomaly on July 11, 2024. SpaceX’s investigation team, with oversight from the FAA, was able to identify the most probable cause of the mishap and associated corrective actions to ensure the success of future missions.

Post-flight data reviews confirmed Falcon 9’s first stage booster performed nominally through ascent, stage separation, and a successful droneship landing. During the first burn of Falcon 9’s second stage engine, a liquid oxygen leak developed within the insulation around the upper stage engine. The cause of the leak was identified as a crack in a sense line for a pressure sensor attached to the vehicle’s oxygen system. This line cracked due to fatigue caused by high loading from engine vibration and looseness in the clamp that normally constrains the line. Despite the leak, the second stage engine continued to operate through the duration of its first burn, and completed its engine shutdown, where it entered the coast phase of the mission in the intended elliptical parking orbit.

A second burn of the upper stage engine was planned to circularize the orbit ahead of satellite deployment. However, the liquid oxygen leak on the upper stage led to the excessive cooling of engine components, most importantly those associated with delivery of ignition fluid to the engine. As a result, the engine experienced a hard start rather than a controlled burn, which damaged the engine hardware and caused the upper stage to subsequently lose attitude control. Even so, the second stage continued to operate as designed, deploying the Starlink satellites and successfully completing stage passivation, a process of venting down stored energy on the stage, which occurs at the conclusion of every Falcon mission.

Following deployment, the Starlink team made contact with 10 of the satellites to send early burn commands in an attempt to raise their altitude. Unfortunately, the satellites were in an enormously high-drag environment with a very low perigee of only 135 km above the Earth. As a result, all 20 Starlink satellites from this launch re-entered the Earth’s atmosphere. By design, Starlink satellites fully demise upon reentry, posing no threat to public safety. To-date, no debris has been reported after the successful deorbit of Starlink satellites.

SpaceX engineering teams have performed a comprehensive and thorough review of all SpaceX vehicles and ground systems to ensure we are putting our best foot forward as we return to flight. For near term Falcon launches, the failed sense line and sensor on the second stage engine will be removed. The sensor is not used by the flight safety system and can be covered by alternate sensors already present on the engine. The design change has been tested at SpaceX’s rocket development facility in McGregor, Texas, with enhanced qualification analysis and oversight by the FAA and involvement from the SpaceX investigation team. An additional qualification review, inspection, and scrub of all sense lines and clamps on the active booster fleet led to a proactive replacement in select locations.

Safety and reliability are at the core of SpaceX’s operations. It would not have been possible to achieve our current cadence without this focus, and thanks to the pace we’ve been able to launch, we’re able to gather unprecedented levels of flight data and are poised to rapidly return to flight, safely and with increased reliability. Our missions are of critical importance – safely carrying astronauts, customer payloads, and thousands of Starlink satellites to orbit – and they rely on the Falcon family of rockets being one of the most reliable in the world. We thank the FAA and our customers for their ongoing work and support.

 

[darthgently]

10 hours ago, tater said:

https://www.spacex.com/updates/

 

So the problem came down to having an unnecessary part and the solution was to remove it from the design.  If the sense line was what I picture it was a long thin tube leading to a diaphragm sensor.  The hollow tube would contain the full pressure of the oxygen and these tubes are typically very susceptible to vibration and fatigue. 

Rockets apparently can also suffer (horribly) from too much bureaucracy in their parts structure.  

[CBase]

Suprising the part survived so long in a "best part is no part" company

[darthgently]

5 minutes ago, CBase said:

Suprising the part survived so long in a "best part is no part" company

It is surprising.  I'm wondering if it was intended as a temporary debug addition to better understand the fuel/ox flow issues. 

It's like "Macro-Heisenburg Uncertainty" where attempted measurements overly impact the underlying process

[tater]

 

 

[tater]

New T-0 of 12:59 Eastern

[tater]

later now:

 

[CBase]

 

[mikegarrison]

On 7/26/2024 at 5:15 AM, CBase said:

a "best part is no part" company

I've pointed this out before, but "Elonism" aside, reducing part count and the "KISS principle" is standard engineering practice and has been for time immemorial. SpaceX is in no way special in regard to this.

[Elthy]

 

[CatastrophicFailure]

So, this is interesting…

At Vandy, I believe. 

[tater]

2 F9 launches tonight. 1 from FL, 1 from CA

[tater]

 

[tater]

3 in a little over 24 hours. Not bad.

 

[AckSed]

1 hour ago, tater said:

3 in a little over 24 hours. Not bad.

That's a point. If we take into account the lead time to integrate the payloads, sail the barges out, permits and all that... that is 17 x 3 tons to LEO. If Vast succeeds in jazzing up their Haven-1 module with a proper life-support module, and Russian-style self-docking, navigation and thrusters you could essentially prep in about a month, and launch a triple-Salyut space-station in a single day. It'd take longer to assemble, but I feel a small ember of hope that this is within possibility.

Or we could have a backup Dragon on standby if the Artemis III docking experiment goes awry.

[darthgently]

FAA appears to be willing to accommodate up to 25 launches per year from Starbase. 

Including, if I'm reading this correctly, landing Starship at Starbase after deorbit.  Mexico notwithstanding?

Anyway, looks like a positive direction

https://arstechnica.com/space/2024/07/although-its-not-final-spacex-just-got-good-news-from-the-faa-on-starbase/

 

[mikegarrison]

It could be a way to deliver SS/SH, if everything works out.

Consider the Boeing Renton factory (where they made B-29s, and then 727s, 757s, and 737s). The runway is quite short, and typically airplanes built there take off and never, ever return (the end of their first flight is usually at Boeing Field in Seattle).

Starbase could be similar -- they could build the vehicles there, and launch them to a landing elsewhere. Potentially.

[CBase]

3 hours ago, mikegarrison said:

Starbase could be similar -- they could build the vehicles there, and launch them to a landing elsewhere. Potentially.

Although starship is the most cost effective rocket ever build, any launch transport will be considerably more expensive than a sea transport. Unless they consider the worth of a maiden flight and therefore flight proven booster/ship higher, we will unfortunately not see air deliveries like from plane factories.