Starship Hot staging
SpaceX ChatThread by @mcrs987, inspired by @JoshLoweSpace.
This thread shows my current theory on how Starship will hot stage, using existing hardware we can see. This was announced recently, so the majority of this is speculation.
So let’s start off by completely ignoring this ring. This ring is what a lot of people think is for hot staging. I think contrary, for 3 main reasons. (Image via @tdsn19)
Reason 1: This ring is obviously not very structurally sound with that many cutouts. SpaceX is already having problems with the payload door cutout on the ship, so having even larger holes probably won't help at one of the most critical points in the vehicle.
Reason 2: That ring was marked for SCRAP over a week ago now, and there so far is no others seen. They have not worked on that ring at all since It rolled out and has been sitting outside tent 2 for about a month.
Reason 3: If we assume that the struts in this ring get stringers, it would not match the same number of stringers that are on the booster forward section. Though it does match the number of stringers on the ship aft end.
So, let’s get on to my idea. On January 6th, this mysterious ring with 20 holes and a bunch of stringers rolled out into the ring yard. Originally speculated to be for HLS, this ring was placed outside of tent 2 for a while and was recently scrapped. (Image via @LabPadre)
However, a second one was spotted on May 23rd. This one is much cleaner and uses the same materials the rest of the ring use, rather than the milled steel of the first one. We can clearly see angled nozzles pointing up. (Image via @CosmicalChief)
Though this specific ring was later sleeved with an eDome and placed outside the midday, and will soon become a part of the “midbay monstrosity” as I like to call it, there may be many more inside Starfactory being prototyped. (Image via @RGVaerialphotos )
This ring is what I believe will be used for the hot staging system. It is clearly very rigid and allows for vent ports. Elon said yesterday that the hot staging will be used on IFT-2, so the current fleet of booster have to be modified.
Elon said the booster would be ‘extended’, but did not specify how much. Just a single one of these rings would do the job. The video below demonstrates how they could convert the boosters.
Though it may seem simple it is a bit more complex than I have illustrated it. All of the wiring and hydraulic lines to the clamps have to be extended one more ring, and would have to be shielded. Speaking of shielding…
Notice the black dome here. We don't know what kind of shape they would use for shielding the sensitive hardware on the booster’s forward dome, so I just chose another eDome. They could coat it in whatever thermally absorbent material they use on the engine shielding.
Now, let’s get into the reasoning of why I believe this is the way to go.
Let’s go way back to the 1960’s, with the Titan 2 rocket. Titan 2 used hot staging. (Though, the interstage blew apart anyways) notice the jets coming out the side
Titan used vent holes at the base of the interstage to allow the stage to separate cleanly without blowing itself up. The Titan 2 interstage is much longer than Starship’s so I feel there's less of a risk of it disintegrating
Take a closer look at the interstage. Notice any similarities between it and this ring? Both have vent holes facing away from the direction of flight, meant to direct gas away. (Image via @CosmicalChief)
Using this, and using a dome as a diverter for gas to escape through these vent holes, I believe we have found an efficient solution to this problem, without compromising the structure. (Image via @RGVaerialphotos)
Another thing with this idea is that the Engine chill pipe isn't going to be vaporized. With the ring with cutouts from earlier the engine chill pipe would be in the middle of one of the holes, and would be vaporized. Not good. With this ring that doesn’t happen
Also a fun bonus to this, if you make the vents able to open and close on command, you could use the thrust from the second stage to help flip the booster around
Now, let’s talk ground infrastructure.
With an extension like this, the ship Quick Disconnect would be too low to actually reach the plate on the ship. They will have to extend the QD upwards. (Image via @RGVaerialphotos )
This is actually less of an issue than it may seem. They are not moving the entire arm, just the QD plate. After the launch of S24/B7, the QD plate was removed from the arm, and the reason why is now obvious. They are upgrading it to fit this new height.
They have actually done this in the past, between S20/B4, and S24/B7 as shown above
This may also be why the QD arm at the LC39A starship tower has not been installed yet. SpaceX was anticipating this design change and is clearly waiting on starship to finish evolving so the designs won't have to be retrofitted last minute, like basically all of Starbase.
Here’s some eye candy for y’all
