Engineer Reveals the TRUTH behind SpaceX's Hot Stage Plans
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- Опубликовано: 10 окт 2023
- I decided to dig in and do the math to figure out what's going on with SpaceX's out-of-nowhere plan to hot-stage the world's biggest and most powerful rocket. Elon Musk recently tweeted that they would be reworking the next flight vehicles so the ship could fire its engines while it was still attached to the booster. Before we watch the next Starship launch live, let's break this down with a proper engineering analysis to see why SpaceX is making the switch. Will this end in disaster? Let's find out!
Наука
bring on the calculations and code. some of us can take it, the rest of us can skip over it.
Yes, exactly
Good summary, but I have a few comments:
1) I believe that "ullage" is pronounced with a short "u", i.e., "ull-age" not "you-lage." It comes from the winemaking world where it refers to the air space in a cask that has been partially used.
2) The very first N-1 flight did do staging. The main problem was multiple fires in the propellant plumbing of the first stage engines. When it became clear they were going to have to terminate the flight, they manually staged it to get some data on what happens. It did turn out that the 8 second-stage engines punched some holes in the LOX tank of the first stage, leading to more heat shielding for later tests.
3) The Titan missiles also used hot staging between stages 1 and 2. The vents are both the round and rectangular holes seen on the interstage skirt.
Interesting analysis. My concern is that the ship blast-heat will weaken the hot-stage structure and it may have to be replaced on regular basis. Possibly not a huge problem.
I think the time is short enough, and the thermal mass of the shield is high enough, that the temperature should not jump by too much, certainly no worse than welding
good analysis. I know you put a lot of work into it but as a viewer, it would be nice to see more data on the screen with fancy charts and comparisons.
Thanks, I think if I was watching I'd want to see a bit more as well. The video I did a few months ago did show some plots of the raw data, different values obviously but a similar profile.
Good breakdown especially now we've seen how well it worked, and how significant ullage was after the booster relight.
We need to hope that the hot staging does not damage or destroy the booster and/or starship.
It will definitely be more visually interesting when you get to staging. I'm certain it will work.
10:00 KarQ intro jumpscare
Didn't one of the N-1's have a structural failure of the latus interstage structure?
I don’t remember hearing that and, from a quick look through Wikipedia, my it looks like that wasn’t the primary cause for any of the failures, the closest is when the shutdown of the center engines caused a structural failure (but that was in plumbing not the interstage)
Are we not putting the cart before the horse here. They still have to sort out Stage Zero. Which is still not guaranteed the deluge system will work.??
Well there would be no reason to 100% nail down stage zero just to change it later by adding this ring, which moved the connections on the ship upwards. Also it would be sort of a waste to test stage zero with a rocket that can’t reliably separate, especially because they have the time to make these improvements while they’re waiting for government approval on the changes to stage zero
Well it worked anyway
"youlich" damn I had to go back to understand what was actually meant
They need to heat tile the segment
The heat tiles are designed for a very different environment, much lower density gas sustained over several minutes. The hot stage ring just needs to survive a few seconds (if that) before the heating drops off dramatically as the stages separate. Steel very well could be fine as it won’t be able to absorb much energy in such a short time
It's "uh-luj" you "you-luj"
the Russians have used hot staging since the 50s.its pronounced uh luhj
Sometimes I only realize I’ve been pronouncing a word wrong when I hear myself say it during editing
There is a fundamental problem with your analysis. You assume full thrust of the SH Booster during full duration of liftoff until MECO. Full thrust of SH Booster just before MECO due to diminshed mass of the rocket tranlates into total acceleration rate of over 5g or more than 50m/s^2. During last test flight maximum acceleration rate recorded by telemetry data was 7m/s^2 that gives you total acceleration of 17m/s^2 when you add gravity loss. Now, at this 30% of acceleration you specify the Skirt of the Starship partially collapsed due to compressive force generated by Raptor rocket engines. Space Cadets at SpaceX are going to great lenght to try to hide this major structural flaw of their rocket. Adding hot staging ring without any diagonal stiffeners assures that the this ring will twist around main axis of the rocket and collapse like dominoes even before the rocket clears launch tower. Now do some math on compressive force acting on the Skirt during liftoff as fuel and oxidizer in tanks of SH Booster gets consumed. Remember that this two stage rocket travels as one utill separation so both parts have to experience same acceleration at all times while mass distribution is changing.
The reason I didn't improve on the throttling was for simplicity and because I was just looking at a rough comparison to see if a 10% increase in payload is plausible, not trying to predict an exact payload feature.
As for the skirt collapsing I haven't seen anything indicating that type of failure prior to the loss of TVC (after that it seems more likely that the abnormal side loads would be the issue rather than just acceleration). The prototypes, including the hot stage ring, have all been tested in their hydraulic test stand so I would be surprised if their margins were as far off as you claim.
@@ConHathy You obviously have no idea about stress analysis and failure modes of edge compressed rigidized metal membranes. Frankly, I do not expect you to even know that such subject exist in mechanical engineering. It is also very unlikely that Elon Musk or any of Space Cadets on his payroll ever heard of such subject. Regardless, their testing methods using hydraulic cylinders are deeply flawed. The Skirt of the Starship same as Hot Stage Ring have, due to their design, primary failure mode that is twisting around Z axis (main axis of the rocket). Elon's hydraulic test stand externally restricts rotation of test objects around Z axis giving false positive results. BTW check raw telemetry data and you will find out that Elon's rocket mysteriously lost TVC but it did not loose throttle control to the very end.
@@KarolKarolak Hindsight is 20/20. The 2nd launch has occurred now. It appears hot staging worked.
@@glennac During second test flight Starship did not carry enough fuel and oxidizer to reach Hawaii islands so it had to be exploded after separation to hide the fact that Elon and Space Cadets cheated one again. Yes, Hot staging works when Starship fuel and oxidizer tanks are less than half full during liftoff.
Thanks for not including calculations and code. I can’t take it
Lol
👉 "Promosm"
Sorry, this guy talks too much nonsense. He doesn’t make things clear! 😂