Space and Science BS Thread

I could barely watch it. Musk is a terrible public speaker and that had to be his worst event I’ve seen.

 

Everyone calls for a public Starship update but he’s been giving updates all along. Not sure what people were expecting.

 

Most rocket engines melt their combustion chamber. Since most are 1 time use they just make sure there is enough metal to last through the flight. There are also techniques to minimize it like running fuel rich. That tends to be less efficient though, and at 2,000lbs of fuel per second per engine, efficiency matters, so they walk a thin line.

 

I’d like to see it fly as well but not by skimping on due diligence. I hope they do a good job without back room influence.

 

He said they might have a tower on a platform by the end of the year, not guaranteed for the launch system to be on it. Makes me think they're going to launch from starbase and try to land somewhere where they won't have to clean it up if/when it crashes.

 

He said Phobos and Deimos are for when launches are becoming more common (3X a week or 3X per day). Keeps the loud noise 20-30 miles off shore and away from population centers.

One thing that really stood out to me is he said the propellant pumps in the Tank Farm have the capability to refuel Booster in 30 minutes.

 

How often do they replace F9 nozzles? To achieve rapid turn around they can’t be having to replace them or even inspect while refueling. Seems to me the Merlins and Raptors have to walk a different line. Edit- more in the case of Raptors though since that’s their stated design goal.

 

So many things to go wrong with no chance of correcting many of them in time. Our understanding of physics from subatomic to astro is still so rudimentary in that we model to imitate results while still arguing over which model is best. None of them truly represent reality, they just imitate small pieces of it. We brute force our way up there pushing a collection of technology to the limit. When it fails we see that limit staring back at us. Seems to me that Rocketry is mostly about amazing engineering and it will take leaps in physics to change that in any dramatic way.

 

That's their eventual intended use. F9 sets off car alarms miles away and is as bright as the sun, and that's with only 9 engines not 33. Last month they started the process of building a catch tower on it, but full launch capability isnt expected until later this year at the earliest. He also said though that he expects to lose the first few rockets on landing. He doesn't expect it to be as many as F9 when they started trying to land those, which was 14 according to him, but they are expecting to lose some.

https://youtu.be/3N7L8Xhkzqo?t=4114

They haven't really been open about what they refurbish between launches. The rumors are they rebuild the engines. We know that the engine mounts are modular making them easy to remove so it makes some sense, but again it's just rumors. The main problem they're having with melting the engines is because they're making them more powerful. V1 raptor produces 185 Tons of thrusts each. V2 230 Tons, in other words they went from being able to lift 92 Tacomas to 112 per engine, and they want another 10 tacomas per engine(250 Tons). This will either give them increased payload, or they won't have to run them as hard and will have headroom in case an engine or 2 fails.

A lot of it is going to be trial and error at first. They have a working design, with a couple of v2 prototypes with over 700 seconds of run time on the test stand. We know they'll continue testing, but the amount of trouble it is to test them 1 by 1, it might be more advantageous for them to strap them onto a ship, launch it a time or 2, and then dissect them. 42 engines tested at once instead of 1 by 1. They did similar with F9, but there's a lot more openness about Starship than there was/is F9.

 

Another thing I'm wondering is how they will make a tank farm on Phobos and Deimos?

 

I hope this becomes an industry standard. Much more relatable than the ‘ton’.

 

They'll probably just use tankers. They should already be setup for docking to them. Then just a bunch of tanks under the deck.

 

If Raptors can only do a single launch cycle before replacing them then rapid turn around isn’t feasible. The orbital tanker would have to remain in a parking orbit much longer or we’d need a lot more refueling launch vessels. Is it possible to achieve a stable retrograde orbit that keeps the tanker fixed in the earth’s shadow? Would it be possible to have the motor section decouple from the fuel tanks and have many of those to speed the process or is it better to just have a bunch more rockets?

 

Not Space
Not really science

Physics or mechanics.

But how does the return trip happen? Where does the energy come from to move the supporting blocks?
youtube.com/shorts/yY_w1uozitY?feature=share

Is it only that the supported block is pressing at an angle and just needs a jiggle?

 

When the last block drops it goes to flat clearing the path for the preceding one yada, yada, yada. Math(simple geometry, diagonal, long edge & short edge). The overlap on the first pass is slightly less than the difference between the length of the diagonal and the long edge.

 

He noted in passing that R2 is still basically a prototype and that they will have worked out R3 bell coolant issues by the time they are ready for full time rapid reusability.

 

Now that’s more like it. I suppose if they expect to lose rockets on first landings anyway it doesn’t make sense to put the longest lasting ones in place. Learn what they can from the prototypes they have.

 

I guess maybe L2 might be an option to minimize exposure to solar heating?

 

Answer is no, best possible is slightly less than half its time in the sun.
https://space.stackexchange.com/que...earth-orbits-in-continual-shadow-of-the-earth

 

Yada Yada

There are internet videos where the return wave "just stops"

What kept that block from shifting over?