totm nov 2023 SpaceX Discussion Thread

[mikegarrison]

Just now, cubinator said:

You could do 100 people if every one of them is perfectly fine with never being alone.

I guess it all depends on timescales. I can pack onto a subway car with many other people, but I wouldn't want to live for several days like that, much less months.

I've done some mountaineering and I know what it's like to be stuck in a small tent with other people for extended periods of time....

[CatastrophicFailure]

2 minutes ago, cubinator said:

You could do 100 people if every one of them is perfectly fine with never being alone.

We do this now, after a fact. It’s called a nuclear submarine. 

[magnemoe]

Just now, mikegarrison said:

So I guess that was it. Nothing really new here for anyone who has been following this. Mostly just a platform for Elon to talk about why we need to go to Mars.

Yes pretty much an waste in my opinion. 
its idiotic late and I'm just just as drunk. 
But everybody hyped for the stream knew all the stuff. 

[mikegarrison]

Oh, these could be "famous last words": he says relative to building the spaceship, life support will be easy.

2 minutes ago, magnemoe said:

its idiotic late and I'm just just as drunk.

I'm considering that as an option. It's seeming like a better and better idea.

Elon trying to explain that he has come to understand "reduction of part count" and "keep it simple, stupid".

[YNM]

5 minutes ago, mikegarrison said:

Elon trying to explain that he has come to understand "reduction of part count" and "keep it simple, stupid".

What, "the best part is no part, the best process is no process" ?

 

Then just do nothing ?

Edited September 29, 2019 by YNM

[mikegarrison]

And that's it. Questions over.

I hope they served cocoa or something, because that looked cold.

[mikegarrison]

Just now, YNM said:

What, "the best part is no part, the best process is no process" ?

Then just do nothing ?

No, but reduction of part count and keeping things as simple as possible are standard engineering ideas for improving reliability and reducing cost.

Just now, CatastrophicFailure said:

It’s like 85 degrees there right now. 

Really? Huh. OK, no cocoa.

[CatastrophicFailure]

Just now, mikegarrison said:

And that's it. Questions over.

I hope they served cocoa or something, because that looked cold.

It’s like 85 degrees there right now. 

[YNM]

4 minutes ago, mikegarrison said:

No, but reduction of part count and keeping things as simple as possible are standard engineering ideas for improving reliability and reducing cost.

True.

But I'm glad that we have three horses.

[Spaceception]

22 minutes ago, mikegarrison said:

Oh, these could be "famous last words": he says relative to building the spaceship, life support will be easy.

Yeah. To be honest, I'm really hoping sooner rather than later, SpaceX finds problems with life support, and go off to develop specialized systems (and we get a proper presentation for it). Like what food will be grown on Mars, and how will it be grown? How much energy and mass will the food/air/water/waste systems require? How are habitats going to be built? How will you protect people from radiation? What will the spacesuits look like? How are you going to maintain and repair the interiors/spacesuits/filters of martian dust? I just want to know how SpaceX themselves will address these.

 

The fact he likes the idea of bringing Boring machines to Mars for underground colonies is promising at least.

[insert_name]

1 hour ago, mikegarrison said:

He's saying it will be roomy enough for 100 people. Then he says it's the same volume as the Space Station, on which six people live. Hmm.

He says by next year they will be building a raptor engine every day, but for now they build one every 8-10 days.

Think of the ISS as a research ship and BFR as a ferry, I am expecting that the 100 figure is for the point to point version. Also ISS crew size is limited by the vehicles flying to it, not the volume

Edited September 29, 2019 by insert_name

[tater]

2 hours ago, Raven Industries said:

Refueling seems to be planned as end to end now, rather than the old side to side thing we've seen previously. 

It was end to end long before this.

1 hour ago, mikegarrison said:

I've done some mountaineering and I know what it's like to be stuck in a small tent with other people for extended periods of time....

And then the pressure equalization of some of the people happens in the tent...

 

Edited September 29, 2019 by tater

[tater]

Musk was asked about the Bridenstine tweet. Maybe Jim did it on purpose to elicit this kind of answer as a kick in the teeth to his SLS contractors...

Musk said that maybe 5% of the company was working on Starship, the rest were all on Falcon and Dragon.

5% of the company is building giant rockets in a few months.

[Xd the great]

37 minutes ago, tater said:

5% of the company is building giant rockets in a few months.

His company has 5000 employees? so 250 people is working on starship.

Also, consider the fact that those aren't rockets, but water towers that looks like a rocket and flies like a rocket.

[tater]

 

 

[tater]

The Raptor production change is unsurprising, frankly. They have characterized engine production by now pretty well, so those figures seem pretty reasonable. They can make a Merlin a day already, Raptor is not substantially larger than Merlin.

So assuming most of the Mk1 prototype mass is steel, it's about $500,000 in materials costs (he said $2500/ton). 5% of the company means ~125 workers per SS, and about 6 months to build one. Call it 4 M$ each in labor? It's entirely possible these things only cost maybe 10M each, not counting engines?

[CatastrophicFailure]

Whoah. 

Never realized the BE-4 was that big.

[Xd the great]

11 minutes ago, tater said:

So assuming most of the Mk1 prototype mass is steel, it's about $500,000 in materials costs (he said $2500/ton). 5% of the company means ~125 workers per SS, and about 6 months to build one. Call it 4 M$ each in labor? It's entirely possible these things only cost maybe 10M each, not counting engines?

Difinitely more than 10M. The avionics, fuel tanks, batteries, motors...

Probably in the 40M range. With the engines, 50M.

Still cheaper than a F9 ride.

[CatastrophicFailure]

2 minutes ago, Xd the great said:

The avionics, fuel tanks, batteries, motors...

...are probably recycled from somewhere else. We know, after all, that the batteries are from Tesla, and if the flipper actuators are electric, there's a good chance they're also repurposed Tesla motors. Even if brand new, that's a maximum of $120k-ish (figuring the price of a new Model S) for each battery/motor combo. The avionics are most likely "flight tested" Falcon 9 parts. Whether that's literally flight tested, or just taken from the same new parts bin is anyone's guess, but I doubt if that's in the million dollar range. 

[Reactordrone]

2 hours ago, insert_name said:

Think of the ISS as a research ship and BFR as a ferry, I am expecting that the 100 figure is for the point to point version. Also ISS crew size is limited by the vehicles flying to it, not the volume

ISS crew size is mostly limited by the life support system. When shuttles visited they needed to add supplementary oxygen generation and CO2 removal.

[tater]

Yeah, when they talk 100 people on Starship my eyes sort of glaze over (to Mars).

The fact that the 1 seam rings we've been seeing at Cocoa are the new way, much faster, and somewhat lighter, that's cool. Think of the labor reduction with just 1 seam instead of the number on the Mk1 (hard to tell, it's either 14 or 16 seams). That labor has to in fact be the bulk of the cost of a ring, though the weld of each ring to another is the same.

[tater]

 

 

[mikegarrison]

One thing I didn't know was that they are going with ceramic tiles as their heat shield. Shuttle, anyone? I wonder if that's going to be an issue for them like it was for NASA.

[tater]

2 minutes ago, mikegarrison said:

One thing I didn't know was that they are going with ceramic tiles as their heat shield. Shuttle, anyone? I wonder if that's going to be an issue for them like it was for NASA.

Yeah, that was interesting, though they tested some on the last cargo Dragon, and they attached some to Hopper (presumably for vibration, acoustics, etc).

I can understand that the substrate (steel) can take higher temps, but you have to wonder about any adhesive used, strikes me that would perhaps be the limiting factor. That said, X-37 has some thinner ceramic tiles as I understand it.

One thing that is clearly different on the current prototypes vs the renders: The belly.

On the renders, what are bulges for landing legs on the current vehicle have a flat area between them on the renders.

Dorsal side here:

Engines with the ventral side also visible:

 

[CatastrophicFailure]

4 minutes ago, tater said:

On the renders, what are bulges for landing legs on the current vehicle have a flat area between them on the renders.

Wild guess here, but maybe the gentler curve on the windward vs the leeward side leads to less heating? Like, the shuttle needed the carbon-carbon tiles on the wing leading edges due to the increased heating from the sharper edge, vs the flat belly. The vertical stab LE also had higher spec tiles than the rest of it. 

Or, it might just be a simple aerodynamic thing, more pronounced bulges like the dorsal side might do bad things to the airflow.