BN2.1

Not to be confused with the hybrid test tank with "can crusher" B2.1.

BN2.1 is a Super Heavy booster test tank. It was built using parts of BN2 and put on a modified nosecone stand including hydraulic rams for thrust puck testing. After a test program (2 cryo tests) at the launch site, the test tank has been moved back to the build site. The outcome of these tests and future plans aren't known as of July 2021.

## History

BN2.1 has been tested at least twice. A first cryo proof test was conducted on June 8 and a second one on June 17. After some inspections, the test tank has been moved from the launch site to the build site (near SN15 and SN16).

## Timeline

* 22 May 2021: Nosecone test stand modified
* 24 May 2021: Nosecone test stand modified
* 25 May 2021: Nosecone test stand modifications continued
* 26 May 2021: Modified test stand to work as new puck shucker for SH test tank BN2.1 as hydraulic cylinders are visible inside the structure [the\_denks]
* 26 May 2021: Test tank spotted in Mid bay [BN2.1]
* 29 May 2021: BN2.1 puck shucking stand hydraulic rams installed
* 30 May 2021: Left mid bay, moved next to tent 3, near thrust shucking stand
* 31 May 2021: Test tanks lifted onto new test stand for thrust test (Modified nosecone stand)
* 03 June 2021: New RCs Mon-Wed June7-9 (12-8pm), possibly for testing BN2.1
* 03 June 2021: Moved to the launch site
* 04 June 2021: BN2.1 work near Pad B, pressure and thrust tests expected soon
* 05 June 2021: Preparation work continued
* **08 June 2021: Cryo proof test #1**
* 10 June 2021: Inspected
* 12 June 2021: Welders worked on the top of the test tank
* **17 June 2021: Cryo proof test #2**
* 24 June 2021: Lifting jig attached, removed from part of its test stand
* 25 June 2021: BN2.1 and its test stand moved from launch site to build site (near SN15 and SN16)
* 26 June 2021: Pad A: Super Heavy test stand adapter mounted to Pad A, previously used as lower part of BN2.1's stand; according to Elon Musk it is planned to use B3 for testing on Pad and make a new booster for flight
* 26 June 2021: BN2.1 and stand now near SN15 and 16
* 15 July 2021: BN2.1 hooked to crane
* 20 July 2021: Aft dome lifted onto sleeving stand [tag ripped off, someone noted B2.1 on it, BN2.1], sleeved with a super heavy aft ring stack, likeyl to practice dome mating with scrapped parts
* 08 Aug 2021: BN2.1 inspection work
* 09 Aug 2021: BN2.1 placed on a concrete stand at PPS
* 27 Aug 2021: Booster inner engine thrust simulater (Triangle-stand) work has continued; same stand was used for BN2.1 testing, as well as part of the nosecone test rig (new info according to NSF)
* 23 Oct 2021: B2.1 (not same as BN2.1) work continued
* 03 Nov 2021: B2.1 work continued near gate A3 (NSF confirms the other one to be BN2.1)
* 11 Nov 2021: BN2.1, GSE4, B2.1 and SN15 shown at PPS; workers prepared concrete forms at PPS near them
* 17 Dec 2021: Rocket garden at PPS: B5, BN2.1, B2.1, SN15, B6, SN16
* 16 Feb 2022: B2.1 and BN2.1 next to each other at PPS

## 08 June 2021 - Cryo Proof Testing #1

On 08 June 2021, SpaceX conducted a cryo proof test including loading the test tank with liquid nitrogen. Likely, the thrust puck was tested as well using the hydraulic rams integrated in the test stand.

Timeline according to LabPadre:

* 12:36 Sheriff at road block
* 15:43 Pad clear
* 17:44 Venting under BN2.1 as well as on top
* 17:51 Frost slowly beginning to appear
* 18:32 Top venting increasing again
* 18:45 Frost reached second topmost line (weld-line to dome)
* 18:51 Recondenser
* 18:58 Top venting stopped, indicating pressurizing the tank has started
* 19:06 Some frost disappearing, possibly as pressure increases
* 19:18 Frost decreasing more rapidly to a lower level, reached at 19:27
* 20:51 Tank farm activity
* 21:25 Frost slowly beginning to disappear
* 23:03 Top depress venting
* 23:05 Frost disappeared; a lot of tank farm activity visible
* 23:09 Road opened
* 23:13 Little condensation/frost appeared again at the bottom
* 23:33 Top vent stopped
* 23:45 Frost disappeared
* 00:30? Bottom venting stopped
* Early morning: tank farm venting slowly decreased

## 17 June 2021 - Cryo Proof Testing #2

Timeline according to LabPadre and NSF:

* 12:xx Road closed
* 12:35 Pad cleared
* 13:00 Venting from BN2.1 skirt
* 13:00 Small venting from top valve
* 13:05 Frost appearing slowly
* 13:40-13:50 Top venting increased slightly
* 13:56 Frost nearly covering full tank up to second line
* 13:57 Top venting stopped, pressurisazion
* 14:00 Frost beginning to disappear
* 14:22 Frost disappeared to second line
* 14:48 Top valves opened, venting slowly increasing
* 14:52 Frost growing again, reached second line at 14:58
* 15:20-35 Top venting increased
* 15:41 Venting increased even more for one minute and then decreased a bit again
* 15:43 Ice falling off, condensation above second ring
* 15:44 Tank farm activity
* 15:47 Condensation up to the top [between second and first line]
* 15:51 Top venting slowly decreasing
* 16:07 Huge short vent
* 16:12 Pulsing vents
* 16:21 Big short vent again
* 16:57 Big short vent again after venting has decreased; afterwards some decrease and increase
* 17:20~ Frost slowly beginning to disappear
* 17:35 Venting decreased a lot to very minimum
* 17:44 Frost holding above second line
* 17:50 No more top venting
* 17:55 Frost decreasing now
* 18:10 Top vent appearing for about one minute
* 18:20 Ice falling off
* 18:45 Frost reached a lower line
* 19:00 Frost decreasing further
* 19:56 Cars to pad; road opened; frost nearly fully disappeared