The SuperHeavy booster 4 is the first booster planned to make an orbital launch together with Starship SN20. On August 6, 2021 it was fully stacked with SN20 on top of the Orbital Launch Pad (OLP). SN20 was further destacked on the same day and on August 10, B4 was removed from the OLP, too.

As of Nov 2021, Starship SN-20 / Ship 20 was slated to be tested for the First Orbital Test flight, launching on top of Super Heavy booster 4. The test will be no earlier than March 2022. The test involves separation of the booster and splashing down in the Gulf of Mexico, while Ship 20 will accelerate to orbital velocity and will re-enter over the Pacific Ocean splashing down near Hawaii. But on Feb 10, 2022, the SN-20 and B4 were stacked for Elon Musk's presentation at Starbase. Days later, SN20 was unstacked from B4 again. It is unsure which Ship will fly to orbit first.

Vehicle details:

B4 consists of 36 rings with grid fins. It has 20 fixed Raptor engines on the outer engine ring and 9 gimbaled Raptors on the thrust puck dome. 

There are 4 sets of COPVs in pairs at the bottom portion of the booster and two power units, too.

1:100 Scale paper model (Updated on Feb 15, 2022)

Download B4 metallic version:

B4 Super Heavy booster metallic

Alternate method to build the B4 using metallic paper and a transparent sticker foil: 

B4 Super Heavy booster sticker paper

Metallic_Starship_transparent_sticker_guide

3D printed optional parts for SN20/B4:

3D Raptors by Wei hao

3D Grid fins for B4 by Sofie Brink

3D Suborbital pad by Arco Hollestelle

3D Orbital pad by Wei Hao

Photos by: Drew Brickell, Alexander Oehms, David Di and DJCorny

Download this file to update your old B4 if you have already built it:

SN20-B4 AXMUpdates

Starship SN20-B4 update guide