sevenperforce

What I wrote (on another forum) on September 30, 2019: Close-up views of the lunar Starship show a blunt nose with a docking port on top. I think this very likely is intended to enable round-trips without using Orion or Gateway. Lunar Starship launches to LEO and is refueled. Dragon 2 launches to LEO and docks; the whole stack heads to the moon. Dragon 2 stays in high lunar orbit while the Starship goes to the surface and then back up. Crew returns on Dragon 2 (which actually has sufficient props for an Earth return) and Starship does a slow series of low-energy aerobrake passes to return to LEO for refueling.

Clearly talking about tank-pressure-fed hot-gas thrusters. Two problems here. First, the preburners are the heaviest part, so you are basically adding more than a third of the weight of a whole Raptor for each thruster. Second, Raptor is a full-flow staged-combustion engine that uses separate preburners for separate turbopumps. The LOX preburner+turbopump is pushing small amounts of LOX into the CH4 preburner and the CH4 preburner+turbopump is pushing small amounts of CH4 into the LOX preburner. So can't run one without the other unless you have a ground system to do so. Finally, the new thrusters are being dev'd for RCS to begin with.

Or resistive heating from the battery packs. Also the tanks will be half full on landing, which means a LOT of pressurized gas to tap off. No, it needs to be full size because it is launching from elliptical earth orbit and it needs to make it all the way back to LLO at least. SpaceX doesn't intend any lunar Starship to be one-way, so the cargo lunar Starship will look the same. No TPS.

RVac would burn at max thrust; RSL would burn at minimum thrust gimbaled toward the RVac to cancel torque.

Using the transfer stage to get back to Gateway (or to Orion) is certainly the most efficient use of props. It uses the same tanks the whole time but refills them from other modules. Presumably both positioned in LLO.

How to obviate SLS: Launch uncrewed Orion to LEO on DIVH, NG, Vulcan, or FH. Use an empty ACES, NGUS, or F9US and a docking connector to deliver uncrewed Orion to HLO. Send the lunar Starship to EEO on Superheavy. Refuel the lunar Starship in EEO. Send astronauts on Dragon 2 to rendezvous with the lunar Starship in EEO, transfer, land, mission. Lunar Starship takes astronauts to LLO where they meet Orion, which takes them back to Earth. Lunar Starship slowly aerobrakes down to EEO.

Fascinating... Someone on NSF spotted that the render has a braking burn afterglow on just two engines. Insane detail.

They are supposed to be 10-tonne thrusters. Maybe 11-12 with longer nozzles. I spy three banks with three nozzles each, so nine nozzles. That gives you 971 kN. Let's say that the lighter, streamlined lunar Starship masses 180 tonnes once it gets back to LLO, ballpark. That means it needs to weigh about 300 tonnes on the lunar surface. To hover 300 tonnes on the moon you need 486 kN. Considering cosine losses, I think nine hot-gas RCS thrusters are exactly right for this job. No, it's a hot gas-gas meth-GOX thruster using autogenous tapoff.

Single-engine transfer stage, double BE-7 descent stage, single-engine ascent stage. I wonder if the transfer stage is a crasher.

The presser says they use refueling modules at various locales. Correct, SpaceX says this will not operate in atmo after initial ascent.

Bridenstine said the Gateway probably wouldn't be involved for the 2024 mission.

This is wholly new.

It is available and it was selected. What am I missing? It has a low center of gravity, thanks to the engines.

It says that there will be refueling modules. Also, on the call: "It is not likely that we will use the Gateway for the 2024 mission."

"Starship is a fully reusable launch and landing system designed for travel to the Moon, Mars, and other destinations. The system leans on the company’s tested Raptor engines and flight heritage of the Falcon and Dragon vehicles. Starship includes a spacious cabin and two airlocks for astronaut moonwalks. Several Starships serve distinct purposes in enabling human landing missions, each based on the common Starship design. A propellant storage Starship will park in low-Earth orbit to be supplied by a tanker Starship. The human-rated Starship will launch to the storage unit in Earth orbit, fuel up, and continue to lunar orbit." I spy oval-shaped engine exhaust ports on the sides. I wonder if those are SuperDracos. It would avoid the "digging up the ground" landing issue. Use those engines for touchdown and liftoff; use vac raptors for the major dV budget.

The Dynetics model looks a lot like the two-stage ascent/descent version I proposed a few months ago. The three-stage ILV looks like a big descent stage that handles transfer from LOP-G to the surface, an ascent stage that jumps from the lunar surface to LLO, and a reusable crew capsule that goes back to LOP-G. Which I also proposed.

Three stages! My guess is that the landing stage provides transfer from LOP-G all the way to the lunar surface, the ascent stage gets back to LLO, and then the reusable crew capsule goes back to the LOP-G by itself. Pretty much the exact design I suggested a few months ago, although probably with an extra engine. Dedicated moon landing version.

BESPOKE MOON LANDING STARSHIP LANDER WITH SIDE-MOUNTED ENGINES Super cool. Might not be a crew lander. Wait, I'm wrong.

Then why isn't it already being flown on legacy rockets? I think you meant 5%. But no matter. Starship has a diameter of 9m; its cylindrical section is 37.1m and its ogive section is 11.7m. The heat-shielded portions of the fins are roughly half the total body shield area. So the shielded surface area of the (roughly conical) nosecone is 11.3% of the total shield. More than half of that can use the same hexagonal tiles. QED. Heating is not even if I am, say, braising a roast. Or using a really thin tile...which you can do if your backshell can take temps up to 1000 K.

Sigh. We've been over this many times. Jupiter-DIRECT was a Shuttle launch stack with (or without) a DCSS on top. SLS uses a different core stage (because the ET wasn't strong enough) and different SRBs. Ares 1 was less of a paper rocket than SLS at this point. Raptor is an actual, flown component. And it's the whole rocket. Take any rocket in existence, swap the first-stage engines for an appropriate number of Raptors, and the one with Raptors wins in raw payload capacity. The shuttle didn't have square tiles; it had 21,000 differently-sized tiles that all fit together like an intricate jigsaw puzzle. 95%+ of Starship tiles will be interchangeable. Why can I put my dutch oven in the oven at 550 F but not my coffee mug? Let's face it, both are ceramics. Because Starship tiles endure less punishment and are not stuck on with glue that degrades. Correct. It was also about foam strikes from being side-slung. Also not an issue. Because they were thick and multilayered, to protect the fragile underlying aluminum that Starship doesn't have.

I will probably add a checkout cell with something like "ALERT: Too large to fit in VAB" and "WARNING: Rockets over 160 m are unlikely to yield accurate data with this ascent profile and characteristics." I would like to find a mathematical relationship for structural density. There is a point where it should start to scale up.

Because even expendable, it leaves SLS in the dust. There's very little similarity between the tiles on Starship and the tiles on the Shuttle. There's also quite a bit of distance between a flying water tower and a leaky one.

I set it up so you can only edit the greyed cells. But the sandbox is fine too. Hmm, I wonder where I could find that info. Here we go. 456 feet or 139 meters. I wonder how tall the MLP was.

Oh good god. "One of the major risks anticipated in our test of this nuclear reactor is that it may trigger a chain reaction."

Ah, thanks. I went into my code and it looks like I used to have a cell that summed the PLF mass and the LES mass but I ended up moving it and Google Sheets failed to change the pointer. Just fixed it in all sheets. Note -- even though the "Build: 3 Stages to the moon" tabs appear locked, they are not; you can still edit the greyed parts. What was the excess dV for? Is that excess past TLI? Which VAB?