Ship 28 (S28)

Ship 28 (S28) is a prototype of the Starship second stage that was assembled in March and April of 2023.
This prototype introduced a new stacking method. Instead of assembling the two halves of the ship separately (nose cone + payload + forward section; aft section + midLOX tank + common dome), they now stacked it from top to bottom.

This approach allowed the crane to remain attached to the nose cone throughout the entire process. Additionally, welding robots were able to work on the ground rather than at a significant height.

However, it remained unclear how they would incorporate the CH4 transfer tube, as it was no longer possible to lift it into the LOX tank from above.

Ship 28 is the next ship to fly on IFT-3 with Booster 10.

## History

Ship 28 was first spotted around July 2022, with stacking beginning in the 9th of March 2023 and finishing less than a month later on the 6th of April. While it was in the High bay, the old two-point lifting jig was tested on S28 and subsequently lifted it off the turntable on the 25th of April. Aft flap installation begun on the 25th of May inside the High bay with work finishing on the 20th of July 2023. When it was then lifted onto the Massey's ship puck shucker. The following day, it was transported to the Massey's test site and conducted 2 cryo proof tests. On the 28th of July and the 3rd of August respectively. It left Massey's on the 4th of August 2023 following its cryo test campaign, and was brought back to the rocket garden where it would it would be lifted onto the engine installation stand to receive its engines. On November 23, Ship 28 was transported back to the High Bay. On the 14th of December, Ship 28 was transported to Suborbital Pad B for a static fire test. Ship 28 performed a static fire test of 6 engines for full duration on the 20th of December. Following this test, the payload door was also tested. 9 days later, on the 29th of December, Ship 28 performed another static fire, this time with a single engine. SpaceX later posted on X that it was an flight-like startup for an in-space burn. On the 4th of January 2024, Ship 28 was rolled back to the High Bay for pre-flight work.

## Timeline

Click to view the timeline:

* 21 July 2022: S28 AD and AS:4 come outside.
* 22 July 2022: S28 aft sleeved, moves back into Tent 1.
* 05 August 2022: S28 aft dome section flipped.
* 12 August 2022: S28 smooth fwd dome spotted in the dome yard.
* 29 September 2022: "S28" AD moved into Starfactory.
* 05 October 2022: S28 nosecone TPS tile installation spotted in tent 3.
* 12 October 2022: S28 payload section PEZ dispenser installed.
* 13 October 2022: S28 payload barrel moves into tent 2 after receiving PEZ dispenser.
* 03 November 2022: S28 nosecone outside tent 3.
* 04 November 2022: S28 nosecone in tent 3 again.
* 09 November 2022: S28 starlink dispenser lifted into wind break/low bay.
* 30 November 2022: S28 nosecone in wind break.
* 01 December 2022: S28 nosecone, tiled but no flaps installed yet, outside tent 3.
* 05 December 2022: **S28** and S29 nosecones in tent 3.
* 13 December 2022: S28 nosecone had its flaps installed, outside tent 3.
* 03 January 2023: S28 common dome flipped.
* 04 January 2023: Presumed S28 mid LOX section comes back out into the main yard.
* 27 January 2023: S28 nosecone moved to ring yard / high bay.
* 02 February 2023: S28 nosecone and mid LOX sections spotted.
* 06 February 2023: S28 nosecone outside tents.
* 01 March 2023: Lifting point attached to S28 nosecone.
* 06 March 2023: S28 lift points attached.
* 08 March 2023: S28 NC moved to the High Bay for stacking; S28 PL moving into the High Bay for stacking.
* 09 March 2023: S28 nosecone lifted in high bay, stacked on top of payload bay section.
* 15 March 2023: S28 N:5 stacked on FX:3 to make N:8.
* 20 March 2023: S28 nosecone attached to crane in high bay [vid 21]; cmn dome section moved into high bay at 18:49.
* 21 March 2023: S28 AX:4 confirmed to be tiled.
* 22 March 2023: S28 nc+payload [add: plus fwd dome] stacked on common dome section in high bay [vid 23] [add: **new stacking method!**].
* 24 March 2023: S28 mid LOX section moved into high bay at 03:13.
* 27 March 2023: S28 was now stacked in a strict top to down method instead of two seperate parts; this way, the crane can rest attached to the nc during the whole process, furthermore welding robots will only need to work on the ground and not high up in the air; however, it remained unclear, how they would add the CH4 transfer tube, as it couldn't be lifted into the LOX tank from above anymore.
* 28 March 2023: S28 lifted and stacked on mid LOX section in high bay at 11:00; only downcomer and aft section missing.
* 05 April 2023: S28 thrust section moved into high bay for stacking; S28 stacking likely aborted.
* 06 April 2023: **S28 stacking in high bay completed.**
* 24 April 2023: **New two-point lifting jig testing started on S28 in high bay.**
* 25 April 2023: S28 lifted off turntable using the new two-point lifting jig at 03:18.
* 25 May 2023: S28 begins receiving aft flaps.
* 13 June 2023: Tiles begin being added to the AX to ML weld on S28.
* 22 June 2023: S28 gets its second aft flap.
* 20 July 2023: S28 transport stand moved out of high bay as ship is being lifted likely to be put onto the thrust simulator from Massey's site; Massey's ship puck shucker moved into high bay and S28 was set onto it.
* 21 July 2023: S28 rolled out and waited at build entrance a few minutes after midnight; **S28 moved to Massey's test site for testing.**
* 28 July 2023: **S28 cryo proof test at Massey's.**
* 03 August 2023: **S28 cryo proof test at Massey's test site.**
* 04 August 2023: S28 left Massey's, moved towards rocket garden.
* 05 August 2023: S28 arrived at rocket garden from Massey's, LR1750 crane picked up the ship lifting squid; S28 lifted onto raptor installation platform at Rocket garden by LR1750 crane.
* 17 August 2023: Raptor engine installation on S28 underway, engine SN164 spotted.
* 23 November 2023: S28 moved from the Engine Installation stand to the High Bay.
* 14 December 2023: S28 moved from the High Bay to Suborbital Pad B.
* 16 December 2023: **S28 performed a spin prime test at Suborbital Pad B.**
* 20 December 2023: **S28 performed a static fire test at Suborbital Pad B.**
* 29 December 2023: **S28 performed a single engine static fire test at Suborbital Pad B.**
* 4 January 2023: S28 removed from Suborbital Pad B and transported to the High Bay for prelaunch inspections.

## Testing Campaign

Overview, without full stack tests:

 03 August 2023
 16 December 2023
 20 December 2023
 29 December 2032

### 28 July 2023 - Cryo Proof Test

SpaceX conducted the first cryogenic proof test of Ship 28, filling both tanks with LN2 completely.

Timeline according to LabPadre discord:

* 18:20 Cryo loading has started
* 18:32 Frost begins forming on the CH4 tank
* 19:15 Ship 28 is fully loaded with LN2
* 22:28 Detanking has started

### 03 August 2023 - Cryo Proof Test

SpaceX conducted a cryogenic proof test of Ship 28 at Massey's test site, completely filling both tanks.

* 17:50 LOX load started
* 19:46 Both tanks fully filled

### 14 December 2023 - Roll out and Lift

Ship 28 was rolled out to the pad with a lot of festive christmas decoration and lights during the night and was lifted onto Pad B by the LR11000X crane. Timeline according to LabPadre discord:

* 01:28 S28 moved out of the high bay
* 03:29 Rollout started
* 04:48 Arrived at launch complex
* 05:01 Arrived at Pad B
* 05:25 LR11000X picked up the lifting squid
* 06:12 Attached to LR11000X
* 10:42 Lift completed

### 16 December 2023 - Spin Prime Test

SpaceX conducted a spine prime test of Ship 28. All engines were used. Timeline according to NSF livestream:

* 6:00 Road closed
* 6:34 PA: "Attention Starbase, the entire pad is now clearing. All personal, please exit the pad now."
* 7:02 Pad clear
* 7:05 PA stopped
* 10:07 Suborbital tankfarm starting up.
* 10:19 Condensation spotted on the LOX tank
* 10:49 Frost line spotted on the LOX tank
* 11:27 Engine chill started
* 11:51 Header tanks venting
* **11:59 Spin prime**
* 12:00 Depress vent
* 14:05 Road open

### 20 December 2023 - Static Fire Test

Static Fire of Ship 28SpaceX conducted a Static Fire Test with Ship 28. SpaceX confirmed on X that Ship 28 did a 6 Engine Static Fire for full duration.  Timeline according to NSF livestream:

* 8:03 Road closed
* 9:04 PA: "Attention Starbase, the entire pad is now clearing. All personal, please exit the pad now."
* 9:57 Pad clear
* 10:34 Small grass vent
* 11:30 Suborbital Tank Farm spooling up
* 12:20 Frost on LOX tank
* 12:36 Some header tank venting spotted
* 12:43 QD venting
* 13:07 Engine chill started
* 13:26 Header tank venting
* 13:28 T-10 Minute siren heard in Boca Chica Village
* 13:28 QD arm venting
* **13:37 Static Fire**
* 13:38 Depress vent
* 13:54 Detanking started
* 15:59 Road open

### 29 December 2023 - Static Fire Test #2

SpaceX conducted a single engine static fire test with S28. This test was "demonstrating a flight-like startup for an in-space burn" per SpaceX. Later in the same test window, SpaceX conducted a 33 engine static fire test with Booster 10. Timeline according to NSF Stream:

* 4:20 PA: "Attention Starbase, the entire pad is now clearing. All personal, please exit the pad now."
* 5:05 Pad closed
* 6:10 Road closed
* 7:00 Pad clear
* 7:56 SoLS tank farm minor venting started
* 8:27 Suborbital tank farm spooling up
* 8:41 Frost line spotted on the LOX tank
* 8:49 Engine chill started
* 9:13 Long vent
* 9:18 Long vent stopping
* **9:19:17 Static fire**
* 9:26 Detanking started
* 13:14 Road opened

### 04 January 2024 - Lift and Roll back

On 04 January 2024, Ship 28 was lifted off Pad B at the suborbital launch site (now a test site) and was rolled back to the high bay at the build site. Timeline according to LabPadre discrod:

* 03 Jan 2024, 16:28 Attached to LR11000X
* 00:21 Lift has started
* 09:12 LR11000X detached from S28
* 11:32 Lifting hooks removed
* 14:55 Movement towards gate D2 started
* 15:03 Entered highway 4
* 21:04 Moved into high bay

## References

1. ↑ https://twitter.com/VickiCocks15/status/1687235565228367874
2. ↑ https://twitter.com/VickiCocks15/status/1687398966512566273
3. ↑ https://twitter.com/SpaceX/status/1737603984997933181
4. ↑ https://twitter.com/SpaceX/status/1737603984997933181
5. ↑ 5.0 5.1 https://twitter.com/SpaceX/status/1740827435673981399