Simple Talk that shows Genius Thinking of Elon Musk

[Music] so the soyuz is a good i mean if i would definitely prefer to ride on the soyuz than the space shuttle um you have an escape system on the soyuz oh and then of course on re-entry um a capsule a blunt body or entry capsule you can be designed to be naturally stable so that even if all the control systems fail that it you know you're just light's not dark everything's you know you're it's it's naturally it's like a shuttle it's naturally stable on reentry and you have to you know do anything there and you can just manually pull the shoots or something like that so in fact that's happened on a couple of soyuz flights where they've had control system failures if that have been the shuttle it would have been curtains but because it's because it's naturally stable you don't have to worry about that and then because you've got that blunt body reentry the heat shield is much more robust because you've got this really big radius heat shield instead of these sharp radius wings so it's really much safer design um and i believe there's never been a fatality on the soyuz which has been going much longer than this than the shuttle man many many more flights so i don't like wings for things that go to space where there is no air let me correct a misconception a a a blunt body sort of a capsule you know gum drop style thing uh is a controlled uh landing um in fact uh because you have you still have a lift vector so you you use offset center of mass to to create a sort of a tilt in in the capsule and that actually creates a lift vector and that lift vector you typically be a drag of 0.2 to 0.3 but that's plenty plenty enough just to steer you where you want to go and in fact even in apollo when they didn't have gps and they uh you know they're really dealing with very very primitive electronics their landing accuracy was a one mile radius [Music] and of course if you can get much better than that with gps and all that other stuff in fact the only error is the wind drift that's the only that's really the only meaningful error and if you um if you have if you do a steerable shoots um or put some like little like a little propeller that popped out or something like that you could you could drop the capsule on the numbers on the runway just like you could drop just like a parachutist can steer their their flight down to a very accurate uh location um and then you can you know i think you sort of like flare it uh just before you go to the bottom just like a parachutist and there you are well mars is the only place where we could really um create a self-sustaining civilization of on a planet scale if you look at the various planets we've got um mercury's too close to the sun i mean the thorax melts on mercury and then venus is still pretty pretty hot uh it's several hundred degrees uh and it's hype and the atmosphere is high pressure and it's acidic so venus would be very challenging um and then mars obviously is on the other side of earth and it's uh it's it's colder than earth but it's it's uh the the temperature on mars actually gets above room temperature on earth on a hot day in the summer um and we you could warm mars up over time with greenhouse gases and kind of the opposite of what we're doing on earth mars atmosphere is primarily carbon dioxide which shows you how long it's been there for billion years especially how long carbon dioxide lasts so when i started spacex it was actually i thought the most likely outcome was that we would fail um in fact i thought that was really very likely that that spacex would fail so it wasn't really with the expectation of success that i started the company obviously um the the but what gave me a clue that we could make a significant breakthrough was looking at the uh the cost of a rocket and instead of looking at it with reference to what other rockets had cost in the past i said okay well what is a rocket made of what are the material constituents um what what metals you know carbon fiber what what what are the various materials that constitute a rocket and if you had a pile of those materials arrayed before you and you could wave magic one what would that rocket cost to build um and that is a remarkably small number um you know it was maybe a few percent or one or two percent of what rockets actually cost so clearly people were doing something silly in how they were putting those materials together um and so just by eliminating those those sort of foolish things we were able to make a rocket for much less and and and then um i wasn't it wasn't obvious to me that you one could achieve uh full and rapid reusability in order to achieve that you really everything has got to be done super super well every aspect of the vehicle um there's uh um you know g loading mxg loading and work dealing with worst-case abort conditions and that kind of thing it says all those things were designed to meet there's one key development item that we need to finish which is the escape tower so that if we have a launch escape system in case something goes wrong with the core booster it can take it can carry the the capsule to safety um it's also something they had during the apollo era but didn't have that for this the space shuttle um and if it's so that i mean that really the two uh weak areas of the space shuttle and the two plus dangers uh periods for uh you know a manned vehicle are during this of the sand phase and the descent phase there are two there are fundamental architectural flaws with with the shuttle approach um one is on the ascent phase there is no escape system they decided they didn't need an escape system because the shuttle would would never would never fail um really i'm like wow okay so so there's no escape system if anything goes wrong on the ascent and then on on reentry particularly the initial part of re-entry which is the high heating point the uh because it's a it's really it's not a naturally stable vehicle you've got to have control surfaces and wings um you know or so it has control citizen wings so if anything happens with the control system so any electronics that don't work on malfunction or or there's a hinge that that you know isn't working properly in one of the control surfaces it's not naturally stable [Music] it has to be controlled and and then the heating rate goes with the square of the radius of whatever you're dealing with so if you've got a wing leading edge that's got a very you know effectively a sharp radius you have a very concentrated heat um which limits the material choice to some very brittle materials in fact um it will only work for for earth orbit re-entry if you come in at a higher velocity than low earth orbit velocity there's no material known to man that can withstand it so actually for like the moon you you couldn't use a winged vehicle it just it's impossible um so um i mean it's not like if you think of polar era okay they had airplanes back then it's not like oh wow wings what are those things um you know the the designers of apollo von braun and and the others were very familiar with aircraft um if they thought wings made sense they would have said let's put wings in this thing they don't when it comes to space wings are dumb just as you don't make an airplane look like a boat like the saturn v although it had five engines on the first stage also had five engines in the second stage and then one engine on the third stage there was actually an 11 engine rocket falcon 9 is got nine engines in the first stage one on the second stage it's actually one total of 10 so one less than 75 and the the advantage of the nine engines is that you can lose an engine at any point including immediately after liftoff and still complete your mission which was not true of saturn v the thrust away the saturn v was about 1.15 so you actually had a very dangerous point immediately after liftoff where you could potentially subside uh if you had an engine failure within the first few seconds with with uh with rockets because you're taking it vertically um you it actually for the first stage it actually for the the initial blue stage uh points you towards having more engines um because if you want true engine out uh capability um because you always have to have a thrust weight greater than one otherwise you're coming back um whereas an aircraft you you can have a thrust rate of much less than one and still be okay because you you can sort of glide and reduce your your climb rate and that kind of thing and still be okay so so it actually it does it does push you to have more than than say like you know 747 you've got four engines but uh the equivalent for a rocket would be some number greater than four and so and maybe it's not as high as nine but we kind of we needed nine to achieve the payload requirements that our customers wanted um and as long as you're very careful about ensuring that the problem with one engine cannot cascade into problems with another engine more is actually better and you know google operates with tens of thousands of computers rather than a few giant mainframes um so i think nine engines is bad uh try 6831 cells i think it's i think it's possible i think we could make it work um they're like doing it this way there's no if we're not violating any laws of physics um it's all it's all do it it's difficult but achievable and and i think we should really try our hardest to to make it happen

Channel: DB Business

Views: 218,275

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Id: ajtgMtDu2iQ

Length: 10min 13sec (613 seconds)

Published: Thu May 27 2021