Angry Astronaut is keeping it real

7.6.24:

More rocket equation calcs show that a 200t cargo capacity MAY be achieveable with what they've got. That is, if it is in expendable mode AND significant mass reductions in the two stages are accomplished. The second stage Starship is a given. But the booster needs to lighten up too. It needs to lighten up by a lot. I figure about 70 tons between the two of them. Otherwise, no can do.

To make things even more interesting, the Jumbo sized combo package, aka Version 3, can get a lot more than 200k per launch in expendable mode. Let's say twice as much useful cargo, giving it about 400t in LEO.

That's sticking with the current profile as closely as possible, without any more alterations. Further efficiencies could involve making a third stage that would chuck the nine engine second stage, and use a different propulsion method to go trans-lunar and landing. You might have as much as 6 km/sec of delta V to play with, provided that you ditch the unnecessary parts as you go, which is what Apollo did. In such a case, 50t may be landed on the moon. (I'm guessing on that one.) If the guess is anywhere in the ballpark, then a direct lunar shot could deliver the 100t that Musk promised before. Two cargo shots, plus the human lander as the third, which has to do a roundtrip from the Gateway.  (Update: piece of cake!)

Refueling would be ditched in favor of a triple landing, which involves great precision in the landing on the lunar part. Not to mention everything else.

Since I'm probably talking out my ass here, include a belated speculation alert.

end of 7.6.24 update of 7.5.24 post



7.5.24:

I did some more tinkering with the rocket equation. It is indeed feasible to get more mass to orbit this way. But catching the booster at the launch site would be OUT. Of course, that is why Musk is making his rocket even bigger. He has already thought about this. Evidently, he prefers to make it bigger than to try an ocean catch. But is the ocean catch out of the question? I guess we'll see eventually.

Anyway, the first stage could definitely be made to work to get 200t up to low Earth orbit. Doing that and making it reusable at the same time is the question.

end update of 7.4.24 post:

12:08 PM

Perhaps Elon Musk is already thinking about this. There was an idea to get an offshore platform, and land the Starship out there. Did that idea die, or is it just put on hold for now?

Let's say that he put an offshore platform out there in the way of the trajectory. The booster comes down and it lands like the Starship. But wait! It has no fins. Ok, put some on. But that would cost a lot in weight! Maybe not. The wings do not have to be large, nor heavy, nor robust. Just strong enough to get by at Mach 5 speed. Or less. Maybe a maneuver to slow it down, and then do a free fall belly flop like with Starship. Anyway, it is a thought.

Oh, by the way... How to get it back to base? Fly it back, and catch it as before... Just need to gas up and take off.

end update of 6:57 AM post.

6:57 AM

Sadly, the Angry Astronaut may be on the right track here. After playing around with some numbers in the old rocket equation, it appears that the booster may be way too heavy. The Angry Astronaut focused on the Starship ( second stage ), but it is actually both parts of the vehicle.

Because the first stage is too heavy, it cannot get the Starship up to speed it needs. Thus, the Starship needs to be more robust, but it is also too heavy. Musk's solution is to make the Booster/Starship even bigger.

It may well prove to be an unworkable solution. I'm still in the preliminary stage of my tinkerings with the rocket equation. A closer view of the launch video shows a stage separation below Mach 5. This low of a velocity means that a large proportion of the propellant must be used in getting the booster back to the launch site because it is much more capable of boosting the Starship than this. The booster must therefore be quite heavy as a result. The reason for its massive weight must be in having to boost back to the launch site, and for this, it needs a lot of propellant. That's my working theory for the time being.

Note: I left this post, and fiddled with the rocket equation some more. I tested this theory, and I think it is probably on the right track.

By the way, there has been some videos discussing a possible ocean catch of the booster. This may be an effort to trim the amount of propellant devoted to returning the booster, and to apply it to a larger payload. (haven't tested this one yet)