#SpaceX is preparing to move the massive new #Starship launch mount structure for #Starbase Pad B to the launch site for installation. In this post, I’ll give an overview of the design and use my 3D models to calculate the structure’s mass in its current configuration. This new launch... mount, nearly an entire redesign, is SpaceX’s best effort at correcting many of the issues discovered with the mount at Pad A after a handful of launches. The only similarity between this mount and the original launch mount for Pad A is that 20 arms will still be used to support the #SuperHeavy booster before liftoff. However, the arms and everything else making up the structure are entirely different.show more

This new launch mount has three main layers. The bottom layer is a truss section formed by four beam sections and four highly strengthened corner sections. Together, they create a square, with the beams distributing the weight of a fully loaded Starship vehicle into the corners and down onto the four pedestals on which the mount will sit at the launch site. The interior of these beams will likely be used for crew access and running pipework, which will provide water and other fluids for the mount’s functions.

The middle layer contains the launch mount's primary structure. This structure consists of 8 main sections, forming an icosagon in the center and a square exterior. These sections contain parallel walls with pivot points for hardware associated with each of the 20 support arms. At liftoff, the 20 support arms will retract into the space between these parallel walls. Large pistons mounted to the base of each pair of walls push and pull on the support arms to actuate them between positions.

The top layer is a water cooled deck. This is the same concept as the water cooled flame deflector for Pad A except this time it is on the top deck of the launch mount to prevent erosion of the deck surface during liftoff and landing. Thousands of tiny holes are drilled into this surface to spray water once the vehicle has started ascending. This water cooled deck will likely have manifolds feeding it from all four sides of the structure. Currently, two sides have manifolds of different designs that have already been installed.

Using my highly accurate 3D models, I can calculate the total volume of objects and then compute their mass with a known density. Since I don’t know precisely what steel is used for most of the structure, I have to guess what density to use. I chose to use 8,000 kg/m³ since that seems pretty average for steels used in applications like this. One thing to note is that the following values are probably a reasonable minimum. I do not have things like weld fillets added to my model, which undoubtedly will add more mass. Additionally, SpaceX has added hardware inside the mount since it has been assembled, making it impossible to see things like pipes and valves. I’m not padding my numbers to account for any unknown hardware, so factor that in when thinking about these numbers.

The bottom truss layer is estimated to be ~33.6m³ of material, yielding a mass of ~300t. The middle primary layer is estimated to be ~70.4m³ of material, yielding a mass of ~563t. The top deck layer is estimated to be ~21.9m³ of stainless steel (using 7,900 kg/m³ for this one), yielding a mass of ~173t. A single support arm is estimated to be ~1.2m³ of material, yielding a mass of ~9.7t. A single large piston for the support arm is estimated to be ~0.085m³ of material, yielding a mass of ~0.7t. Currently, 4 of the 20 support arms and possibly 10 of the 20 pistons have been installed, for a total mass of ~46t. The manifold with the blue pipe and pipe hangers is estimated to be ~1.1m³ of material, yielding a mass of ~9t. The other manifold is incomplete, but currently, with its pipe hangers, I estimate it to be ~2.1m³ of material, yielding a mass of ~17t.

So, with all those detailed numbers, the Pad B launch mount will be a minimum of ~1108t when it rolls to the launch site on SPMTs. However, with all the unknown hardware and welds I can’t account for in my models, I think the actual number is probably closer to 1200 t. If we factor in the mass of the uninstalled support arms and assume the additional manifolds are similar to the heavier manifold, then the launch mount's mass increases to ~1400t. With additional hardware installed at the launch site, this launch mount will easily be 1600+t once fully outfitted.

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@CSI_Starbase Awesome work Ryan, thank you. I have one non-mass related question you might have insight to - do they plan on adding shielding to those gaps at the top of each support arm when retracted?

@CSI_Starbase Good eye. I'm keeping an eye on that area, but I have some theories I'm playing with.

LFG! SpaceX's mount redesign shows why test flights rule. Pad A's pain becomes Pad B's gain.

I truly appreciate how well you pieced everything together by analyzing pictures and utilizing the software. Your knowledge and determination to explain this in a way that all of us can understand is commendable. Bravo! Tony