Thread by @CSI_Starbase

1/11) Hey #StarshipAddicts, I just wanted to take some time to correct some misconceptions I have seen floating around about this event during the WDR. Hopefully this thread will clear the confusion. At the end, I will suggest a possible solution to this issue.

🎥@Labpadre

2/11) To start off, we should all be able to agree that Wet Dress Rehearsal involves Liquid Methane, and Liquid Oxygen. There is zero nitrogen involved, other than for super chilling of propellants and various gas purges (interstage & OLM/OLIT)

3/11) Now, lets take a look at the depressurization vents on top of the methane tank of the booster. There are no pipes on the inside of the tank that connect to these valve. So when they open...you can literally stick your arm inside of the booster methane tank
📸@ChameleonCir

4/11) Before the massive depress purge occurred, the frost level in the tanks was higher than the outlet of the vent. Everything below that line is LIQUID. You can see small amounts of liquid methane leaking from the valve causing a small vapor trail to be visible

5/11) Now, that we can confirm this is LIQUID above that line, we can say for certain that once this valve opens a significant volume of LIQUID methane begins draining from the tank. Kinda sketchy, but there is a good reason for why this is necessary.
🎥@Labpadre

6/11) When the CH4 tank is being filled gas pressure will begin to build up at the top of the tank as the liquid boils off. There is a certain point during the fill process where this must be released in order to continue filling the tank.
🎥@C_Bass3d

7/11) There is approximately 4.52 meters from the outlet of the vent, to the top of the tank dome. If the vent was located on top of the dome, then there would be no chance of liquid flowing out of it, only gas. But that is simply not how this is designed
📸: @ChameleonCir

8/11) Now, there is a possible solution that would allow SpaceX to depress the top of this tank during the last 5% of fuel loading without venting to atmosphere. Its basically the opposite of what we saw them do with the Ship's raptor chill vent.

🎥@Labpadre

9/11 ) Not sure how this fitting works, but it apparently requires no manual connection. Once the chopsticks set the ship on top, the raptor chill vent is relocated below the booster's grid fins, and more importantly, below the cameras on the GSE arm.

📸@RGVaerialphotos

10/11) This can be duplicated on the CH4 tank by routing a vent line up through the interstage and connect it to the Ship QD. From here the depress from the booster CH4 tank can be routed through the Ship QD's Methane bleed line.

Boom no more venting to atm

📸:@ChameleonCir

11/11) Obviously this won't work with the current vehicles, but is an option to consider on future iterations. It severely violates the "best part is no part" rule, but figured I would throw the idea out there anyways.

Thanks for reading and hope you enjoy your weekends!