Mad Rocket Scientist

I wonder if an almost dry BFS could abort during launch on earth. If you're refueling it anyway...

I'm in complete agreement with that. The Boring Co. plan sounds better than cars for that, although it remains to be seen whether it's any better than (or different from) subways. I do prefer it to the "make cars so hard to use that bad public transit is a preferable alternative" plan, but that's just a personal opinion.

The tube is an amazing example of public transport, and I wish LA would get their rear in gear on building something like that. It's worth noting though that the major traffic jams in LA come from commuters driving in from quite low density suburbs. Using pods that can split up and go their own ways has better potential to help solve the problem of connecting those areas, since it would be cheaper to operate with thousands of stations that would be required so there could be one within walking distance everywhere.

Yes, they are. Thankfully someone asked during the presentation. They could be replaced with vacuum engines to increase payload to mars, at the cost of the easily accessible aft cargo. It just about matched up about with our predictions.

It probably will be. I just mean that the Boring Co. is aiming for a kind of network that will include unprofitable parts at some point. Although maybe the roads are crowded enough that the inconvenience of switching transit networks won't matter. I actually agree about trains being better than individual pods for an efficiency standpoint (people-miles/hour) but there are a lot of convenience reasons on the side of individual pods (no waits, can get much closer to your destination, privacy). It also can scale nicely based on how many people are using it, either from minute to minute or over years, just add more pods. That keeps operations costs (theoretically) lower, since you never run empty transports.

I decided to learn how to program my TI-84+ today, and it turns out that in a addition to being able to do anything you want with programs, you can load custom OS's. And it's approved for use on standardized tests. Maybe they figure writing an OS and implementing symbolic computation is equivalent to just studying for the test.

I've noticed this a lot on the forums recently, for example, the "of" in the your post has a zero-width space. Possibly it's being inserted before all "f"'s? I'm going to test it some in the test thread.

I suspect the terminal building would be safer than a grounded airplane, since, while it's hard to overstate the power of even slowly moving water, tsunamis aren't really waves, just rising water. My understanding is that most structural damage to buildings comes from the earthquake, not the tidal wave. Even if the water should reach the windows of the terminal, most airports have 2 or more interior stories in addition to being built 1 story above the tarmac. Maybe an analogous question would be if you would rather be sitting in a tree rooted in the middle of a river, or on a log floating on its surface. EDIT: The real question though is: will an airplane take off from a treadmill while submerged in a tsunami?

Congrats! And check yo' staging.

https://www.spacex.com/sites/all/themes/spacex2012/images/mars/03_TurnTable4.mp4

My understanding was that this was always how it would work. You can practically just copy the Mars Direct logistics over to BFR, just replacing dedicated ships with payloads.

I'm not sure whether to be more worried that you typed umlats for that or that I completely failed to notice the first time I saw it. "So how much will it cost?" I was so happy to hear Tim Dodd asking about the vacuum engines, I was afraid no one was going to.

Or, at the very least, are willing to operate at a loss for an indefinite amount of time until the Boring Co network is large enough to support itself. Keep in mind that single pieces of transport infrastructure (a single road, one train line) are, on their own, not very useful. It's only at a certain size that the entire network starts to be worthwhile. Part of the reason it's so hard to justify building bike paths is that when a city is just starting with bike paths, they end up being roads to nowhere, dumping bicyclists right back onto busy streets after a mile or less of path.

What are they burning? That flame looks so bright and torch like, and there's no shock diamonds.

Also only 3 engines needed for landing. I was afraid no one was going to ask. Especially after two people in a row asking about how much it would cost. Was the raptor in that video throttling?

I would say the 2016 IAC was more like that, since it was the closest thing to an announcement of plans for manned travel to the moon and mars. Although many people already knew that that was SpaceX's plan, so there's nothing which really can compare. Also, will that be a hexaweb?

:hailprobe:

You could try the NASASpaceFlight.com forums: https://forum.nasaspaceflight.com/ I don't have an account there, but they keep everything in separate threads. (For example, there's a thread for every launch with only news of that launch) There's probably still tons of speculation, but it's kept apart from news. reddit.com/r/spacex is the other major fan site for SpaceX. It is larger, but suffers from the problems of reddit in general: threads aren't permanent, and what is popular and visible is not always what is interesting to you. There are some very high quality analyses of SpaceX stuff there every so often, but it's kind of quiet otherwise. The moderation there is in general of a higher quality than the rest of reddit too, although they seem to have been forced to back off from that slightly due to popular pressure, which is a bummer. Finally, you could start a new thread here just for existing SpaceX systems analysis, although there's no guarantee that it will stay on topic. A bunch of threads in the Science and Spacelight section actually were originally part of this thread before the moderators split them off.

Got the demo first, I think I made it to orbit in the demo before I bought the game. I wouldn't have bought the game if I hadn't played the demo first though.

He also calls JP-4 "just about the most permissive specifications to appear since the days of Coal Oil Johnny Rockefeller the First." Also, the quote on burning JP-4 with nitric acid continues: "Everything was tried to make the stuff burn smoothly, from catalysts in the acid down — or up — to voodoo. The farthest-out expedient that I heard of was tried at Bell Aeronautic. Somebody had the bright idea that the sonic vibrations of a rocket motor might promote combustion. So he made a tape recording of the sound of a running motor and played it back at the interacting propellants in the hope that they might be shaken — or shamed — into smooth combustion."

I recall there being some talk of a "virtual aerospike" like this on the ITS booster. You might want to take a look at this: https://www.reddit.com/r/spacex/comments/5ad34y/virtual_aerospike_discussion_background_in/

Sorry, I didn't read your post carefully enough.

They'd have to convert Mvac to methane though, and it still wouldn't be staged combustion.

Maybe raptor has been downscaled again, and those are vacuum nozzles. Or maybe there are two sizes of raptor, and there is still a mix of SL and vac engines, they just have the same nozzle size? I imagine the folding lower fins are so it can reenter stably like the shuttle, then fold up the fins and flip backwards to land.