I also found it interesting, but he even uses existing images to explain what is in that image, so no way in hell is the title legit.
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Scott Manley - Doing The Math On The Spinning Falcon 9 Booster
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Scott Manley discusses (Virgin Galactic) Commercial Astronauts Make Historic Space Flight
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Scott Manley discusses SpaceXâs Shiny Stainless Steel âStarshipâ
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I have a theory about thermal soak:
At launch, the rocket needs to be high pressure and low temperature. During reentry, the rocket only needs fuel to land - and thus youâre reentering the atmosphere and heating up your fuel tanks built to withstand high pressures. Since pressure is directly proportional to temperature, the now substantially reduced high pressure tank can withstand a drastic increase in temperature.
If you have a form of shiny steel that can withstand reentry without plastic deformation, you can then soak that heat into the interior of the rocket, and insulate the cabin. Iâm curious about how thermal soak would be maintained. Some sort of refrigeration and insulation combo would probably work, like channeling heat from the cabin area steel with fluid to the top area of the rocket which can withstand equivalent temperatures to the bottom. Thatâs all I can picture at the moment.
I canât wait to see what the design is. I hope itâs something that is easy to replicate so that other companies can put effort into their own launchers.
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Scott Manley talks about Heat Shields - Things Kerbal Space Program Doesnât Teach
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Heat bleeding into the vehicle last thing you could possibly want during reentry. The challenge of reentry is getting rid of your orbital energy, not absorbing it. 95% of this energy is dissipated during the hypersonic portion and thatâs when you need to dump heat. Typically this is done with an ablative heat shield. It vaporizes and the vaporized particulates carry the heat away. You want to keep as little heat as possible from actually entering the vehicle in as passive way as possible.
As I understood it the goal is to absorb the heat to the entire metal structure and reradiate as a blackbody in IR at whatever the equilibrium temp is(Iâm curious what this is now tbh - I might go dig up some code to calc reentry heating). I think the guy also mentions active cooling using LCH4 which could whisk some of the heat away from the hull. Not sure what you do with the heated ch4 though. Get rid of it in an open loop cycle? Use it for hydraulics? RCS?
Side note: If the outer tank layer is empty then itâs either pressurized a bit or mostly vacuum. If itâs a vacuum then itâs a great insulator for the nested prop tanks for landing. If itâs not a vacuum - you wouldnât want the outer tanks to be high pressure or high temp because it would heat up the landing propellant and cause pressure issues there.
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Yeah, Iâm not sure how much heat would be absorbed - I was just running with Scott Manleyâs discussion where he basically suggested that youâd be reflecting some radiation away with the shiny skin. I hadnât considered no heatshield as a possibility until he mentioned it. Or, maybe just a minimal one.
AnywaysâŚ
If itâs not a vacuum - you wouldnât want the outer tanks to be high pressure or high temp because it would heat up the landing propellant and cause pressure issues there.
My thought here was that youâd have spent most of your fuel, so your high pressure cryo requirement would double as a high pressure heat requirement. Maybe heating of reentry would assist in pressurization for landing.
Iâm curious what the solution is, as Musk said, itâs delightfully counter-intuitive.
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Iâm fairly certain that methane and oxygen are autogenously pressurized(meaning that as they evaporate into gas the pressure stays relatively constant).
This is an old picture but you can see the two tanks within tanks. Those are the landing prop tanks. During reentry the outer tanks should be vacuum and the inner tanks are full.
I forget the exact numbers but during the hypersonic portion of energy shedding a large portion of the heat never actually touches the spacecraft. It gets carried away in the shockwave. However what energy/heat does reach the spacecraft through convection and to a far lesser extent radiation needs to be dealt with. Instead of using ablative pieces to carry that energy away or using tiles that just have a high heat capacity with low thermal conductivity to keep the heat in the tiles, theyâre(maybe) planning to use steel.
Steel has a pretty high thermal conductivity. Usually thatâs a bad thing because youâd want to keep the heat in one spot and not let it get to places that shouldnât be hot. The counter-intuitive bits is that the entire hull is the âtileâ that can absorb the the heat in the belly and conduct it to the steel on the top of the spacecraft distributing the heat and keeping the belly steel from melting.
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I think it would be so cool if this was the case.
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Scott Manley asks, Whatâs Going On With SpaceXâs Stainless Steel Starship?
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I think they are going to really just launch the shittny tin can as a test, but to me it also seems so far from the real thing that the that the testing utility must be kind of small. I guess they have to start somewhere.
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Scott Manley talks SpaceX - Launches, Landings, Layoffs and Silver Rockets Which Assassinate Attempts At Alliteration
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Elon Musk interview about why stainless steel is good for the Starship. I canât tell if itâs genius or going to fail spectacularly.
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Blue Origin Flies To Space While Starship Hopper Blown Over By Wind - Scott Manley
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Yeah.
The tip over slows things down a small amount, but the engineering is finished on the Starhopper, so its just a matter of reordering/re-cutting damaged parts and redoing the assembly. Theyâll probably do a quick rework in case of further high winds.
If the stainless steel works, itâs going to make the rocket a lot cheaper per pound if itâs also lighter and stronger. Thatâs the spooky thing about it. And, if itâs stronger, itâs going to make scaling it up to even larger rockets even easier, which should drive down the price a little bit more per pound.
Moon, Mars, asteroids, gas giant moons, here we come!
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Absolutely! The estimates I saw were essentially on the order of 200-350$/kg for carbon fiber(end of the day assembled product) vs ~5$/kg for stainless steel. Though steel(and carbon fiber) still require some sort of solution to the heating problem. The sims Iâve run estimate max heating between 1200-1700 K for a first order approximation depending on the L/D ratio of the vehicle and its ballistic coeff. The melting point of stainless(type 304) is ~1650 K so theyâre definitely close to where they need to be though the exact number could change depending on additives. Though thatâs from LEOâŚentering from higher energies like from Lunar or Martian orbits would be quite a bit hotter.
Active cooling hasnât been done before in rocketry(for reentry systems) but Iâm keen to see how they implement it. Open Loop Film cooling is nothing new inside combustion chambers for engines so itâs not too far fetched of an idea to use to whisk the heat away during entry.
The starhopper shouldnât have any issues structurally or thermally because their respective loads will be quite small during hops in comparison to orbital reentry so I think weâll see some pretty rapid pacing for on the hopper sides of things. If the hopper tests go well theyâll move to building a fullscale âhopperâ like F9Dev. A ship that big for a completely reusable system you will want to ensure that your systems checkout completely. Plus the fact that the first stage is non-existent publicly at the moment and should also require itâs own hopper to test landing in the launch pad slots.
It will be an exciting next few years!
Moon, Mars, asteroids, gas giant moons, here we come!
Agreed 
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So, they keep missing Mr. Steven. I think they should go out with four boats with a giant net that hangs between them all instead of one small net.
Takes very little engineering to do that, just gotta make sure the boats donât tip with the weight of the nets or fairing, or under their own tension. The cost of the boats would probably be similar to the cost of a couple of fairings, so it would financially make a lot of sense as well. Plus, you save time on your engineersâ salaries, which canât be cheap for world class engineers who live in L.A.
Gyroscopic stabilization is very common on boats, so, I think it would be fine.