Elon Musk Teases Reddit With Bad Answers About BFR Rocket (reddit.com)

Long-time Slashdot reader Rei writes: On Saturday evening, Elon Musk took questions in a Reddit AMA (Ask-Me-Anything) concerning SpaceX's new design for the BFR (Big F* Rocket). But unlike the 2016 IAC conference where many audience questions seemed to be trolling Musk, this time the tables were turned. Asked why Raptor thrust was reduced from 300 tons to 170, Musk replied, "We chickened out." He responded to a statement about landing on the moon by quoting Bob the Builder, while responding to a user's suggestion about caching internet data from Mars by writing simply "Nerd." A question as to whether BFR autogenous pressurization would be heat-exchanger based, Musk replied that they planned to utilize the Incendio spell from Harry Potter -- helpfully providing a Wikipedia link for the spell.

A technical question about the lack of a tail? "Tails are lame." A question about why the number of landing legs was increased from 3 to 4? "Because 4." After one Redditor observed "This is one bizarre AMA so far," Musk replied "Just wait..." While Musk ultimately did follow up some of the trolling with some actual responses, the overall event could be best described as "surreal".
To be fair, Musk provided some serious answers. (And his final comment ended with "Great questions nk!!") But one Redditor suggested Musk's stranger answers were like a threat, along the lines of "Just wait. It will get way more bizarre than that. Let me finish my whiskey."

Musk replied, "How did you know? I am actually drinking whiskey right now. Really."

Comments

Way overblown

[vinn]

I think this story is a bit overblown and sensationalized. I think it was exactly the kind of candid responses people like. In nearly everyone one of those cases he followed up with very technical details of why things were designed the way they were. And to be fair, it was held on /r/space as opposed to /r/spacex and the /r/spacex community sort of invaded the AMA and posted the real technical questions. The nice thing there being a much higher level of technical questions were asked, but it did serve to alienate a lot of the /r/space community who probably isn't used to hearing about deep throttling ratios of methalox engines, etc.

Re:Way overblown

[imidan]

Slashdot has a contingent of users (particularly ACs, but others as well) who will take any opportunity to bitch about Elon Musk and everything he does. You can see it in the comments to this story, where people are making Tesla's setbacks out to be massive failures, or suggesting that the entire company is some kind of grand con job to absorb government money. They seem immune to arguments that Tesla has ultimately delivered what it promised, or that SpaceX has been quite successful with its launches and landings.

This story is comment-bait, I think, to stir up these pointless arguments in an effort to drive ad impressions. The summary is misleading and needlessly disparaging. Though the story is only two hours old, the comment count is already near the median number for every older story still on the front page. That counts as a win for the operators of the site, who are motivated in part by generating site traffic.

Stupid summary

[ceoyoyo]

I read through the AMA. Musk answered all of the top level questions in significant detail. He did add a quip here and there. For example his comment about chickening out, which was followed up by a couple of paragraphs about the difficulty of deep throttling engines and the benefits of having multiple engines for failure tolerance.

The only exception I noticed was when some nerd said "you can't land on the moon with a 3 MN engine" and Musk said "yes you can - Bob the Builder." Seems fair to me.

Re:Stupid summary

[DanielRavenNest]

I'm a space systems engineer (i.e rocket scientist). Of course you can land on the Moon with a 3 MN engine. You just require a 1.5 MN landed weight and 50% throttle capability. The throttle capability is to adjust landing deceleration to make a 0 m/s @ 0 elevation stop. Given the Moon's surface gravity, 1.5 MN --> 900 ton landed mass. That's a *big fucking landed mass* by NASA standards, but that idea is built in the BFR's name.

If you want to do a suicide burn and higher landing acceleration, the landed mass goes down. For example, 1.3 Earth gravities (which is the Earth takeoff acceleration) works out to 235 tons landed mass given 3 MN full thrust. With a fast landing, you would throttle *down* from max thrust to meet the landing condition. That's a more reasonable landed mass, but still pretty big.

Re:Who is being trolled?

[Rei]

At what point do we ask why this guy is given billions of dollars in state and federal subsidies (which is promptly burned)?

If you're referring to the auto industry loans, Tesla paid them back, with interest, years ahead of time. Unlike part of the Big Three loans. If you're referring to EV subsidies, they're available to any manufacturer, and more to the point were specifically designed to be based on the size of the Chevy Volt's battery pack. It's amusing to see the Big Three struggling against an environment that they crafted.

His latest car factory is actually human powered

It depends on what you mean. If you mean, "There are humans involved in stages of the manufacturing process", yes - but more to the point, you're describing every car factory on Earth. If you mean there's no robotic manufacturing, that's wrong. If you mean "the factory is not fully set up / tuned and requires more manual labour than it will in the end", no-freaking-duh, that's the very reason for announced S curve production plan. Most manufacturers, for a new line, will set it up and work on it for about half a year before starting sale of their production. This is not the approach Tesla is taking. While the plant is most definitely being set up for massive volumes, they are at present one month behind their planned production level at this point in time, and even that planned level was only two cars per hour.

and products are overpriced

Nearly half a million people have disagree with you, and put their money behind their disagreement.

Competition is coming,

Hahahahaha ;)

Sorry, it's just we've heard this constantly for the past decade. And there are no signs that anyone else is taking this seriously, despite their best PR efforts to come across that way. Nobody else is working on similar battery production volumes for any given production year. Nobody else is pouring nearly as much money into production and R&D (100% of Tesla's EV-related spending - excepting that directly dedicated to vehicle production, which earns 25% margins - goes into this. Billions per quarter at present). The competitors are literally missing a "0" at the end of their investment figures from what they need to be investing. Nobody else is even remotely close on fast charging networks, the key differentiating factor that actually lets you do long trips in your vehicle. The closest announcement - VW's network (forced on them by CARB) - will not even get close to what Tesla has today when it's done, let alone the scale of Tesla's network by that point in time.

It's funny watching all of the people who see concept cars announced, compare them to Tesla's offerings today, and saying "See, Tesla is about to face serious competition!" Because, again, we've seen this for a decade, but more importantly, it expresses a profound ignorance about how concept cars work. What you see presented as a concept car does not make it to production like that. Regardless of what the company says. They're not designed to be affordable to build, to meet crash standards, to be remotely efficient, and on and on. Most never go to production at all. When they do, they look radically worse (here was the concept Volt, for example), perform worse, and are priced worse. And they only try to sell them where there's pressure on them to sell EVs. Take the Bolt, for example. Go to a Chevy dealership in a ZEV state and there will be Bolts on the lot, and they'll actually push them. Go to one in a non-ZEV state, and the situation is reversed. Go to most

Misleading Slashdot Summary

[SmaryJerry]

He made those answers but ALSO responded in full detail to the same questions.

Re:Distraction

[Rei]

That's what THEY say. There is no public evidence.

Huh? So poor performance firings should require a detailed public airing of the company's grievances against the employees? And what the heck kind of crappy "layoff" would involve under 2% of the company's employee base?

MUCH further behind than that.

False. Here's Tesla's official announced production plan. They're one month off. July was supposed to be around a hundred, August was supposed to be a few hundred, and September 1500. A few hundred were delivered in September. That's one month off.

It's also worth noting that when Model 3 was announced, their initial goal was to start production in late 2017, with no specific numbers for deliveries. They moved the start up by half a year.

And I see you have a history of making excuses for Musk's ...let's say... puffery

Funny, given that people like you keep calling his claims impossible BS, and he keeps delivering the supposed "impossible BS". Do you ever tire of being wrong, or are you always refreshed by the latest opportunity to be even more spectacularly wrong?

Re:to be fair...

[Areyoukiddingme]

The serious answers were insightful, usually a full or several full paragraphs with meaty details suitable for the audience, and honestly impressive that a CEO could do that off the top of his head.

There's a reason Elon Musk self-identifies as SpaceX's Chief Designer more frequently than he self-identifies as CEO. He's making very technical decisions after learning and understanding the ramifications of the options. He has a physics degree, which alone makes him a far cry from most MBA CEOs today, who choose among technical options they literally can't understand based on how much they like the person presenting them.

Re:It was alright

[Rei]

I've noticed that "better metallurgy" often seems to be the go-to solution in Musk's companies - use more exotic/expensive alloys in key areas in order to save a lot of money down the road, and developing the experience working with these alloys. Part of the same thing behind Boring Company, for example - rather than simple, passively cooled steel cutting discs, they plan to use high temperature / high strength alloys and actively cool them. They'll still have to replace then, and the replacements will cost a lot more, but that's nothing compared to the amount of cost savings involved in being able to run the cutting head many times faster.

Re:Distraction

[Rei]

Funny, I must be hallucinating the former existence of the Falcon 1, the present existence of the Falcon 9, the landing and reuse of Falcon 9s, the success of the Tesla Roadster, the success of the Tesla Model S, the success of the Tesla Model X, and now Model 3 production beginning. Every last one of these things endlessly prophesied to be pipe dreams by a doomed, DOOOOOOMED company. And instead: success and consquering each of their respective markets.

Just like the Model 3 will soon be doing. Whether you like that or not.

Those were placeholder answers.

[Omeganon]

OP seems a bit disingenuous. For every one, he followed up minutes later with a more fleshed out and responsive answer. It seems obviously to me that his original comments were markers to track which ones he wanted to come back to.