SpaceX Starship - IFT-4 - Starbase TX - Pre-Launch Preparations Thread

[ecarfan]

I’m a bit surprised the ship was re-stacked, since won’t it have to be de-stacked again to install the FTS?

Maybe they are going to do another WDR.

 

[scaesare]

They need to level their camera... the ship and tower look like they are tilting over... lol.

 

[JB47394]

Maybe they are going to do another WDR.

Another wet dress rehearsal is underway. Note that the countdown is for a Starlink launch.

 

[JB47394]

Wet dress rehearsal complete. Currently detanking. This was a long one, where they left the vehicles fully tanked for roughly half an hour before the Detonation Suppression System (DSS) was triggered, signaling the end of the countdown. The NSF guys were puzzled by the long hold while tanked.

 

[Buckminster]

https://twitter.com/x/status/1795496485611536409

 

[Ben Hinssen]

Interestingly, SpaceX also says there was blockage that prevented the roll control thrusters from operating correctly on Starship:



Are those RCS thruster using ullage gas as Elon mentioned (to Tim Dodd)? If they are gas, the valves aren't flowing liquid... so I wonder what got clogged in them?

The then say they are adding more thrusters to provide redundancy:



The implication being that the thrusters they had should have been sufficient, provided the valves didn't get clogged up...

If the RCS thruster is directly connected to the fuel tank, it could be that random floating blobs of liquid oxygen is being sucked in the RCS thruster. If the liquid then decompresses to gas, it lowers the temp of the RCS manifold/valve even further, freezing the rest of the liquid.
(I'm assuming liquid oxygen as methane is a potent greenhouse gas, and they might not want to vent that just above the upper atmosphere)

Under gravity, it seems logical, liquid stays at the bottom, gas on top. But in microgravity, this doesn't hold. The liquid and gas mix and blobs of liquid fuel/oxidizer will be floating around in the tanks.

 

[JB47394]

Road closures for flight testing activities have been ordered for June 5, 6, and 7.

“I have AMENDED the ordered of closure of Boca Chica Beach and Hwy 4 for the purpose of
protecting Public Health and Safety during SpaceX flight testing activities on June 5, 2024, in the
time period between 12:00 a.m. C.S.T. to 2:00 p.m. C.S.T. and in the alternative on June 6, 2024
or June 7, 2024, from 12:00 a.m. C.S.T. to 2:00 p.m. C.S.T., of the same day. Should SpaceX not
complete its planned flight-testing activity on June 5, 2024, then SpaceX may use the alternate
dates to complete its testing activities,” Treviño stated.

 

[Ben W]

If the RCS thruster is directly connected to the fuel tank, it could be that random floating blobs of liquid oxygen is being sucked in the RCS thruster. If the liquid then decompresses to gas, it lowers the temp of the RCS manifold/valve even further, freezing the rest of the liquid.
(I'm assuming liquid oxygen as methane is a potent greenhouse gas, and they might not want to vent that just above the upper atmosphere)

Chemistry-wise, I'm not sure what happens to orbital-velocity methane as it reenters. (Thermodynamically, LEO speed is roughly equivalent to the gas being heated to ~80,000C.) It may spontaneously disintegrate into carbon and atomic/molecular hydrogen when it hits another molecule traveling that fast? And the methane boiloff will need to be vented anyway, whether it's used for RCS or not. It may also be possible to combust the boiloff O2 and methane in a controlled way, then vent the result; this could also heat the system and avoid freezing problems.

 

[JB47394]

It looks like the explosives for the flight termination system for each vehicle are being installed. On IFT-3, the explosives were installed six days before launch. June 5 is in 6 days. They've also moved the big crane away from the tower, but I can't tell how far. It's no longer in shot.

This is the latest from nextspaceflight.com's tracking of launch preparations. They've updated with a Mexico NOTAM between 5 and 11 June.

 

[Grendal]

One of the differences for this launch is that IFT-4 will jettison the hotfire ring. This does not mean that this will happen in future launches but SpaceX does want to see if the hotfire ring causes instability in the booster control for the landing process.

 

[ecarfan]

Shows all the good bits; the two DSS tests, a “low pressure” water deluge test, the WDR with all tanks reaching full, the high pressure deluge test.

Still a few tiles missing.

 

[JB47394]

Shows all the good bits; the two DSS tests, a “low pressure” water deluge test, the WDR with all tanks reaching full, the high pressure deluge test.

And while we were all keeping an eye on IFT-4 developments, they removed everything suborbital from the launch site, and also completed the static fire stand with its support equipment over at the Massey's site. Still no word on when they'll try a first static fire.

 

[scaesare]

Tim Dodd's recap of changes for IFT-4: