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AMA of Elon Musk  

2015-01-07 21:39:00|  分类: Discuz |  标签: |举报 |字号 订阅

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本来1月6日会进行CRS5发射并进行第一级箭体海上降落回收的,为了这历史性的一刻,Elon Musk也去Reddit的AMA回答了很多问题,在线问答汇总如下:

https://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/cng3bhm

I am Elon Musk, CEO/CTO of a rocket company, AMA!

 

[–]codecracker25 39 指標

Question

Answer

Hi Elon! I'm asking three questions on behalf of the nearly 20,000-strong fan community /r/SpaceX. We consider these the best questions we'd like you to answer for us (trust me, there were hundreds more), so a response to each would be much appreciated! 1. Falcon Heavy. Some have speculated that at stage separation the Falcon Heavy center core is too far downrange and travelling too fast to be feasibly returned to the launch site. Could you go into some detail on whether you plan to use barge landings permanently for this core, expend it depending on the mission, or take the payload loss and boost back to the launch site? 2. Mars. Could you please clarify what the Mars Colonial Transporter actually is? Is it a crew module like Dragon, a launch vehicle like Falcon, or a mix of both? Does it have inflatable components? Is MCT just a codename? 3. Spacesuits. How does SpaceX plan to address the limitations and contribute to the advancement of current spacesuit technology to best serve humans enroute and on the surface of Mars? You mentioned in 2013 that there'd be an update to SpaceX's "spacesuit project" soon - how is it coming along? Thanks for taking the time to do this AMA! Also at some point, /r/SpaceX would love to have an AMA with someone such as Gwynne Shotwell, Steve Jurvetson, Hans Koenigsmann, or even yourself - so if we could organize something for the future that would be great! And finally, just in case your work and this AMA hasn't already made you aware, you're launching Falcon 9 in less than 12 hours (the 19th SpaceX launch & 14th F9 launch no less!), so here's a countdown clock & website I built for you. Best of luck with Dragon & the landing! Regards, Lukas.

1. Yes, the Falcon Heavy center core is seriously hauling a** at stage separation. We can bring it back to the launch site, but the boost back penalty is significant. If we also have to the plane change for geo missions from Cape inclination (28.5 deg) to equatorial, then a downrange platform landing is needed. 2. The Mars transport system will be a completely new architecture. Am hoping to present that towards the end of this year. Good thing we didn't do it sooner, as we have learned a huge amount from Falcon and Dragon. 3.Our spacesuit design is finally coming together and will also be unveiled later this year. We are putting a lot of effort into design esthetics, not just utility. It needs to both look like a 21st century spacesuit and work well. Really difficult to achieve both.

I’m a teacher, and I always wonder what I can do to help my students achieve big things. What’s something your teachers did for you while you were in school that helped to encourage your ideas and thinking? Or, if they didn't, what's something they could have done better? thanks!

The best teacher I ever had was my elementary school principal. Our math teacher quit for some reason and he decided to sub in himself for math and accelerate the syllabus by a year. We had to work like the house was on fire for the first half of the lesson and do extra homework, but then we got to hear stories of when he was a soldier in WWII. If you didn't do the work, you didn't get to hear the stories. Everybody did the work.

Hello Mr. Musk, I sold you a pair of hiking boots at the Sports Authority Elite in Corte Madera. I just wanted to know how your walk through the forest (as you described it) went? Also did you like the boots?

Yeah, they were great

What daily habit do you believe has the largest positive impact on your life?

Showering

Hi Elon, I'm already saving up for my Model 3. Can you share anything about the Model 3 that we don't already know?

It won't look like other cars

tl;dr: How do you learn so much so fast? Lots of people read books and talk to other smart people, but you've taken it to a whole new level. It seems you have an extremely proficient understanding of aerospace engineering, mechanical engineering, electrical engineering, software engineering, all various subdisciplines (avionics, power electronics, structural engineering, propulsion, energy storage, AI) ETC ETC nearly all things technical. I know you've read a lot of books and you hire a lot of smart people and soak up what they know, but you have to acknowledge you seem to have found a way to pack more knowledge into your head than nearly anyone else alive. Do you have any advice on learning? How are you so good at it?

I do kinda feel like my head is full! My context switching penalty is high and my process isolation is not what it used to be. Frankly, though, I think most people can learn a lot more than they think they can. They sell themselves short without trying. One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to.

Hi Elon. A friend of mine is all paranoid about the computer singularity, and used your name as a source of his paranoia. Don't you think it could all be a bunch of hype? Awesome car/rocket/etc stuff you do! Huge fan!

The timeframe is not immediate, but we should be concerned. There needs to be a lot more work on AI safety. And, with all due respect to the Roomba dude, that is not a concern https://www.youtube.com/watch?v=Of2HU3LGdbo

Has the Raptor engine changed in its target thrust since the last number we have officially heard of 1.55Mlbf SL thrust?

Thrust to weight is optimizing for a surprisingly low thrust level, even when accounting for the added mass of plumbing and structure for many engines. Looks like a little over 230 metric tons (~500 klbf) of thrust per engine, but we will have a lot of them :)

Hi Elon, I'll leave the technical questions to the experts. 1. do you plan on getting any sleep tonight and 2. how will you celebrate if the test is successful? Best of luck! x

Yes, but probably only a few hours. Party at Cocoa Beach!

Follow-up question: How much do you sleep per night, on average?

I actually measured this with my phone! Almost exactly 6 hours on average.

Hi Elon, I currently work for Toyota Tsusho in Fremont doing the wheel assembly for Tesla. I want to let you know how proud I am to be however minutely linked to such a powerful and positively influential company such as yours. Keep doing the good work, sir. You are an inspiration to not only myself but countless others around the world. My question: You seem to have had to deal with a tremendous amount of adversity in a few of your ventures. Do you have any advice for those dealing with seemingly insurmountable adversity?

There is a great quote by Churchill: "If you're going through hell, keep going."

1. Previously, you've stated that you estimate a 50% probability of success with the attempted landing on the automated spaceport drone ship tomorrow. Can you discuss the factors that were considered to make that estimation? 2. In addition, can you talk more about the grid fins that will be flying tomorrow? How do they compare to maneuvering with cold-gas thrusters?

1. I pretty much made that up. I have no idea :) 2. The grid fins are super important for landing with precision. The aerodynamic forces are way too strong for the nitrogen thrusters. In particular, achieving pitch trim is hopeless. Our atmosphere is like molasses at Mach 4!

[–]codecracker25 4 指標

Question

Answer

SpaceX's current strategy revolves mostly around old style Rockets, even if they are now approaching complete reusability (Grasshopper rocks). Has SpaceX looked into Hybrid craft like the SABRE program happening in the UK, or look into the possibility of a space elevator (Even at a thought experiment stage) in the way that Google and NASA have done?

If you want to get to orbit or beyond, go with pure rockets. It is not like Von Braun and Korolev didn't know about airplanes and they were really smart dudes.

There has been a lot of speculation over comments about exactly how much mass you are hoping to send to the Martian surface with the MCT (Mars Colonial Transporter). Can you tell us how much cargo you would like to be able to land on Mars with MCT, not including the mass of the MCT itself?

Goal is 100 metric tons of useful payload to the surface of Mars. This obviously requires a very big spaceship and booster system.

1. What is your favorite airplane? 2. What is your favorite video game? 3. What is your favorite food? 4. If you consume alcohol, what is your favorite alcoholic drink?

1. SR-71 Hard to pick a favorite. 2. I tend to like FPS with a story, like Bioshock, Fallout or Mass Effect, but was also a big fan of Civ and Warcraft. 3. French and BBQ. 4. Whiskey.

How will you secure the first stage of the Falcon 9 to the barge when it lands? Gravity or some mechanism?

Mostly gravity. The center of gravity is pretty low for the booster, as all the engines and residual propellant is at the bottom. We are going to weld steel shoes over the landing feet as a precautionary measure.

In order to use the full MCT design (100 passengers), will BFR be one core or 3 cores?

At first, I was thinking we would just scale up Falcon Heavy, but it looks like it probably makes more sense just to have a single monster boost stage.

Europa: attempt no landing there. True or false?

There should definitely be a science mission to Europa.

Would you ever consider becoming a politician?

Unlikely.

In your recent MIT talk , you mentioned that you didn't think 2nd stage recovery was possible for the Falcon 9. This is due to low fuel efficiency of kerosene fuel, and the high velocities needed for many payloads (high orbits like Geostationary orbit). However, you also said that full reusability would be possible for the Mars Colonial Transporter launch vehicle. What have you learned from flights of Falcon 9 that taught you a. that reuse of its second stage won't be possible and b. what you'll need to do differently with MCT to reuse its second stage.

Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system. MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).

What kind of mass ratio do your upper stages have?

With sub-cooled propellant, I think we can get the Falcon 9 upper stage mass ratio (excluding payload) to somewhere between 25 and 30. Another way of saying that is the upper stage would be close to 97% propellant by mass.

Emily Shanklin indicated in late 2013 that the Raptor would be the first of a "family of engines" designed for the exploration and colonization of Mars. Could you elaborate on her wording, i.e. was she simply referring to a vacuum version and standard version, or do you plan on building multiple methane-based engines with significantly different thrust and size specifications?

Default plan is to have a sea level and vacuum version of Raptor, much like Merlin. Since the booster and spaceship will both have multiple engines, we don't have to have fundamentally different designs. This plan might change.

Design life of Merlin 1D has been mentioned to be 40 “cycles”. Could you expand on what a “cycle” is? Is it just a start of the engine?

There is no meaningful limit. We would have to replace a few parts that experience thermal stress after 40 cycles, but the rest of the engine would be fine.

What are your memories of Pretoria Boys High?

Good school

 

概括说一下,Falcon Heavy的芯级将在前向海上降落以保GTO运力,Falcon Heavy的上面级要进一步做到25~30的质量比,或者说97%的质量都是燃料。Raptor发动机回归现实推力降低到500千磅/230吨,MCT计划要做到把100吨货物送到火星表面,而且要搞单芯怪兽!这要多大直径呢,发动机并联数量恐怕少不了30台吧。
满塞,N-1回来了,科罗廖夫大师你死的早啊,米辛没搞成,居然要一个南非出生的美国籍友人来继承您的梦想。
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