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any cool behind the scenes stuff? He was quick the the reupload

I think you can figure out that I mess up the lines sometimes, that I sometimes rewrite lines on the fly, and that I have a dog who sometimes walks into and out of the room. I don't think I swore in this one, but sometimes that happens when I mess up a line for the fourth time in a row.

@@EagerSpace when you first posted the video I was writing out a comment but couldn't post it because you took the video down. Jokingly I suggested an alternate title; "How the Sausage is Made - Is Elon Right?"

I'm glad that somebody like that comment.

​@@EagerSpaceyour calm dilevery added a lot too

Deadpan snark heeds no generational barriers

"Verbiage" is generally considered to be a derogatory term ("excessively lengthy or technical speech or writing") but I get your point and agree! This info was useful with some humor. 👍

@@tonybrock5288 Merriam-Webster: “Verbiage has a second sense meaning, simply, "wording," with no suggestion of excess. This second definition has sometimes been treated as an error by people who insist that verbiage must always imply excessiveness, but that sense is well-established and can be considered standard.”

It also hints at Starship having marginal economics.

@@saumyacow4435 I'm sure it is. We've had spaceflight for nearly 70 years. The first commercial passenger flight was only 7 years after the first powered flight. It's obviously very hard to do this economically.

This is roughly speaking intentional, since engines are expensive and gravity losses aren't large enough that you should overprovision them, whereas fuel is comparatively cheap despite diminishing returns. A Saturn V densely packed with Raptors could have an incredible T/W.

Yes. But the factor I used applies across across the full cost of getting to orbit, which includes drag and gravity losses. So it's not really true that I'm ignoring them, I'm just assuming they scale at the same rate as the velocity energy does. Which is, as I noted, obviously the wrong thing to do.

More than fair. My instinct is that the "real" answer is probably even more exaggerated than this good approximation suggests, rather than less exaggerated. I think gravity losses would not scale linearly could contribute, but I haven't done that math either.😅

@@darylbardo Gravity losses aren't too large with Starship. It has a T/W of around 1.5 at liftoff, so even with 1.1 times the gravity, the T/W would still be pretty good at something like 1.35. You could also expect that a Starship designed for higher gravity would have had more engines and higher thrust. A Saturn 5 designed for 1.1 times the gravity might have had six F-1 engines. The penalty would primarily have come in the form of added dry mass, cost and complexity, while the reduction in payload would have been modest. The gravity losses may even have been reduced overall, by adding the sixth engine.

Astronauts have a maximum acceleration, gravity is part of that accelertion, so T/W ratio couldn't be increased to compensate for increased gravity. There is also a matter of max Q which limits the early T/W ratio even of unmanned launches. With increased gravity you would also get a denser atmosphere further effecting max Q.

Well, since the original comment talks about air density too I think it is fair to accept that the comment is 'for a given atmospheric density, 10% more gravity would be a problem'. So no - no one said that 'a planet that formed with 10% higher gravity......'

I wouldn't be surprised if 10% extra gravity would equal multiple times the atmosphere. I can't imagine that result would be linear

Huh... How about DeltaV? Wouldn't higher gravity planet with same diameter require higher velocities to stay in orbit? TWR, maxQ is one thing, but I think DeltaV would be really hard. Look at difference in DeltaV requirements between Leo, MEO and GEO. F9 can lift 20+ tones to Leo, but 8.5 tones to gto. So if you would need as much deltaV to heavier Leo as currently to gto, probably you wouldn't have any margin for recovery.

@@just_archan ultimately needing a higher twr at lift off means you get less fuel to build horizontal velocity. so yes, you need more delta v to start with, but twr further compounds that issue.

@@etherealswordsman3214 I don't deny TWR issues, but more important imho is amount of propellant that rocket have to carry

:0) Jelly Spots, a kinder humanity!

And even worse, leaving the planet would be impossible

​@@mostafamohammedahmed3404not with nuclear rockets.

Your ultimate point is still right though, we need simulations to optimize the losses

Yes, I made a *hell* of a simplifying assumption, but I think the answer is at least directionally correct. Building the right simulation for a specific rocket without knowing the real numbers nor knowing the actual flight path they plan to follow doesn't seem very tractable.

Thanks.

KZfaq is not the place to learn rocket science this video is radically oversimplified but it’s correct starship is a serious payload problem. If you really wanna learn this and the complexities of what it really takes with different types of vehicles, get a copy of explain and some textbooks on aeronautical engineering, and Space exploration

I think the answer to both of those is probably "yes".

Definitely. It would have a much higher altitude to its "edge". it would be more dense where it matters most, plus our entire current atmosphere after that. there may be some aspect of lift from the extra density that would compensate in some way. I'm also not quite sure what percentage it would add to atmospheric density relative to 10% more gravity.

The difference in more gravity & how different the physical characteristics of the vehicle would have to be, is kind of a mute point, because it likely would mean that we would either be somewhat different developmentally/evolutionarily or life might not of even emerged.

Heavier planet ≠ thicker atmosphere. See Titan Vs Earth, or Venus Vs Earth.

@@matthewkantar5583 Those all have vastly different circumstances. A better comparison would be: Titan: M = 135 Et, P = 147 kPa Triton: M = 21 Et, P = 1.5 Pa Pluto: M = 13 Et, P = 1 Pa Similar densities, internal structures, temperatures, and atmospheric compositions.

I did a little research there and then I was happy that Elon only spoke of gravity so I got to assume the same size earth with higher density.

I was just getting ready to comment this same question.

Go back and watch the part where I talk about "simplifying assumptions"... I think the answer is that atmospheric differences matter but not a lot.

​@@EagerSpacewell maybe not for launch but reentry i see two key differences Im guessing smaller flaps would be needed But you would need more robust tjermal protection im thinkin tps would cost more in terms of weight then the flaps would save but have no way of checking how big of a penalty that would be

​@@yakirfrankoveig8094You could just reenter at a higher altitude with the same air density. The 10% faster orbital velocity would be an issue since it would increase temperature by ~21%.

@@kolbyking2315 yeah i considered reentering higher when i wrote that comment because you enter at the same air density but at a faster speed so you would experience more heat from the begining as you said and it would also persist throught the whole regime since you will also be slowing down quicker and therfore dropping faster into thicker atmosphere than you would on earth

That was about average for my raw takes; it was a retake this morning when I finally figured out that the last one had a disk error in the middle and was unusable.

@@EagerSpace You should put raw takes as patreon exclusive (jk)

That would seem to be a disincentive to joining...

My guess is that the expendables are going to have roughly the same shape as Falcon 9 does; definitely true for Vulcan. I think a "payload versus delta v" chart is a bit more interesting and relatable. Lunar and martian both require a lot of delta v and it's not that far apart, so you need the same sort of vehicle for both.

Starship is planned to be single-stage to Earth with no refilling, so that .38 gravity multiplier is doing some work.

Mars is ridiculously easy to get off of.

​@@EagerSpace So is the moon. Apparently you could manufacture Aluminium structures like girders and plates and throw them into LMO from surface, to build space stations and large spacecraft. No need for on board propellant. The moon could be quite a good ship building yard! What do you think?

​@@EagerSpaceOh, I forgot to say how much I enjoyed your video. Keep up the good work!😊

A higher gravity doesn't increase the amount of atmosphere. It just increases the density at sea level, while the density drops off faster for higher altitude. The rocket still has to get through the same amount of atmosphere, it just gets through more of it at the start, while it is is moving slow. I think the situation with drag would be improved, overall, if the vehicle is designed for the same TWR. You would clear the densest part of the atmosphere quicker, and you could perform a more aggressive gravity turn.

Also we dont take into account other factors that come from that like sea level thrust in a higher density atmosphere or higher drag to to the hypersonic speeds(speed of sound is lower). So everything points to how much harder this would be.

Drag loss is low, typical around 100 meters per second, or only about 1% of the total energy cost to get to orbit. Rockets just aren't moving very fast down low and they get above the atmosphere fairly quickly. See web.stanford.edu/~cantwell/AA284A_Course_Material/Karabeyoglu%20AA%20284A%20Lectures/AA284a_Lecture7.pdf

@@EagerSpace But what I am saying is that forces due to drag mean that the rocket has to be throttled back in the lower atmosphere operating at below peak efficiency. As with all these things, one small effect impacts many others which in total equal a much larger total impact.

was about to comment the same thing. it's way more complicated than just pretending the rocket is 10% heavier chatgpt says 400km LEO speed is ~7650m/s and 400km LEO speed with 10% gravity increase (same size planet) is ~8050m/s. so roughly a 5% increase. still, neglecting this extra dV, neglecting extra gravity loss and extra time to fight that increased gravity loss, neglecting thicker atmosphere seems like too much of an oversimplification..

@@sebastianstan20395:00 he shows delta V increasing due to higher gravity. I think there are other factors though - thicker atmosphere, etc.

@@jrherita you're right, I missed that somehow or maybe I thought that's the equivalent dV to reach normal LEO speed with a 10% heavier rocket. at least 5% seems to be correct. intuitively though, seems like 10% in gravity increase should mean way more of a penalty than what's calculated in the video...

@@sebastianstan2039 I agree - I am also surprised the increase in gravity has less effective than 1.0x

The point was to come up with a gravity factor and use that as a multiplier for the entire cost of getting into orbit, so it's basically assuming that all the factors that control the overall delta v scale at the same factor. That is obviously wrong - the factor will be different in for different costs - but it's directionally correct and simple enough to be explainable. Producing a more robust calculation is left as an exercise to the viewer...

That would be funny. It would be a pain to gather the data, however. The interesting thing on Elon Time is that if it's less than 2 months, it's pretty much 1:1. At least in some cases.

1) Perhaps. See "simplifying assumption" 2) Yes.

Thanks.

There's another video in the works that will dig into this a bit more. I haven't done any numbers but I suspect the loading on ascent when it's full of fuel is much higher than re-entry when it's empty. It is in another direction. I am interested in how neutron turns out because it's the optimized partially reusable rocket they SpaceX didn't try to build, and I expect the economics to be good. Starship is ridiculously hard to develop, but Elon's goal isn't lift to Leo, it's Mars.

@@EagerSpace Fuel and tank pressure on ascent will load the walls of the vehicle uniformly and in tension. In descent you've got several things happening that aren't in your favour. Firstly, the dynamic pressure is high - it's equivalent to hurricane force winds. So you end up with higher g forces overall. Secondly, the flaps act on their hinges and the forces from the flaps are then transmitted into the whole structure which is now being torqued - basically it's like pipe bending. You get a bunch of internal elements that want to buckle as a result. Thirdly, on launch you get internal pressure that actually stiffens the structure, but on descent you've got empty tanks and lower pressure. And fourth, you saw the flapping of the steel sheets on the upper sides of the flaps? That's aerodynamics kicking in. It's basically a cylinder doing a belly flop. there's going to be places where the stream separates and turbulence kicks in. So the steel walls will react by flexing or going into vibrational modes. That in turn will react with the dynamics of the gas stream, possibly creating feedbacks. Bottom line here is that there's a lot of movement going on that is trying to shear and separate the tiles. Tiles can work if you've got an absolutely foolproof way of ensuring they don't crack and don't tear out of their mounting points. I think what Elon is now doing is going for denser (thus stronger) tiles, but there's an obvious price to pay for that. I also have doubts about the ablative underlayer, if its silicon based. It's not that that stuff can't survive high temperatures. Rather its the combination of temperature, charring and then high dynamic pressures and turbulence. See Orion's heat shield. One of the nasty things about plasma is that if its focused by geometry and then comes back to touch something, it's very destructive - a cutting torch. To be honest I was feeling better about this when SpaceX announced it's original intention to have transpirational cooling. Yes, it would be experimental but they could have advanced the state of the art quickly. Maybe arrived at some kind of hybrid with a slowly ablative (reusable 10x) material in certain places. And if you want to know what I'm thinking. I'm thinking what happens when we get a stretched version of Neutron and Rocket Labs starts thinking seriously about a reusable second stage, Stuff like a combination of methane cooling for the engine and ballutes for drag, maybe?

On this video I was trying to address a very specific question, but there's going to be something more general coming up.

Thank you!

yes. But even a big ass scale of production of saturn v's would be more expensive than getting full reusability. Because reusability will give you a monopoly that outweighs every throwaway system. The upfornt cost for digital computers and data handling was absolutely astronomical, until it replaced it by orders of magnitude. I am not an Elon fan either, but this nut needs to be cracked someday. And I don't even think it's going to be Starship, cause the larger you go, the actual better reuse performance you get out of your rocket. The refueling situation will likely be Starships actual killer. Even if Startship is working perfectly, needing a shit ton of refueling missions to perform the actual mission isn't really practical and economical.

And 25t is with my model, which ignores a lot of factors that probably make it lower. There's a biggest discussion to be had, but that will have to wait for the next video...

@Skukkix23 Oh, definitely. Reusability would still be better in the long run, but how would pursuing it be different if it was already difficult to send large payloads to orbit by expending the vehicle? Requiring megarockets to put comparatively meager payloads to orbit may make reusability seem not worth it for a longer time. Astra's idea of 'mass producing' expendable rockets might be pursued instead for a while, attempting to lower costs and increase cadence that way until they hit a ceiling.

@@davidk1308 Yes, I am very much of the opinion of "right tool for the task". And really a lot of stuff would not even require a falcon 9. Just a really cheap rocket would do the trick also. But I am not even remotely qualified to talk about numbers or economics here, also I wouldn't want to come across this. As @EagerSpace mentioned, even 25t is probably generous. I just think full reusability will be a bigger step than actually like discovering a new continent. When you suddenly knew, that there was a new continnent, basically everybody already had ships and the means to travel there. The nation or corporation to get the leap on reusability, will have an exclusive wormhole to multiple new continents. This is highly underrated everywhere you look. Because that continent is maybe not even a different landmass, it's actual economical maneuverability in space. The only reason why we're not more in space is now just a scalable function of cost, not a function of engineering.

@@Skukkix23 Having reusable second stage doesn't make sense ( as you said ) unless it's absurdly big to make use of economy of scale ( which Starship might qualify as ) and only haul stuff to LEO and then come back. When trying to go beyond LEO as is the case with Artemis it's incredibly inefficient which was also the case with Space Shuttle.

Yes, but staging earlier reduces the cost of the boostback burn and means that super heavy can give more Delta v to starship. The tradeoff is complex. And yes, a drone ship would make this a lot easier, but it gets in the way of the operational goals.

Thanks. I've talked about gravity losses before - there's a video on them - but it's not very easy to explain or understand, because - as you note - it depends on time to orbit and it also depends on flight path.

The orbital energy term is the measure of orbital velocity. There are certainly other things that were ignored

It's not quite asymptotic... I think it gets to about 13,000 m/s of Delta v at zero payload.

I'd be skeptical that any entity would be willing to cough up the funding for such a project without the proven history of small launch vehicles. Maybe there is a balance point in there somewhere though.

It's a really, really, really big rocket.

Yes, I estimated how much delta v I thought a fully reusable starship would require. It's more than Falcon 9 but starship requires minimal fuel to reenter - just enough for the landing burn which is pretty minimal. It's dwarfed by the extra weight required.

Hard to say anything for sure, but I think that if it had been harder to get to space, the opportunity for SpaceX would have been greater. The competition would have been that much more expensive, and it would have been easier for SpaceX to persuade investors that there was a market opportunity. Falcon 1 might have flown with Merlin 1C on it's maiden flight instead of Merlin 1A, Falcon 9 might have been Falcon 10, etc. 10% higher gravity wouldn't have been enough to have prevented marked adaptation. We would probably still have landed on the moon, just with Saturn VI instead of Saturn V, as an example.

If gravity was 10% higher, the Falcon 9 might have been a Falcon 10. Or more likely, it wouldn't have been stretched as much. Keeping TWR at an acceptable level but also reducing the payload capacity.

@@SpaceAdvocate Yeah, true, but you'll have put additional fuel if you need to burn for the same duration. Rocket equation is a b***h. Guess it's good think that our gravity is 9,8 not 10.78 m/s/s. Off to try Falcon 10 :)

You got a thumb down from me for your goobbledygook😂

Op knows the difference, but contrary to popular opinion, op is not a robot and therefore sometimes make makes mistakes. A book editor I was writing for once told me "don't let 'perfect' be the enemy of 'good enough'" and I've found that to be sage advice.

Very intresting

There's a video in the works that will deal with that question, among others.

This. With those calculations F9 could make it to LEO with 2x gravity lol. People don't appreciate how on the edge everything is for a rocket, for that to be even a comparison you need 10% more thrust, 15-20% stronger airframe, and proboly 30-50% extra full (as a guess its probly even worse). So F9 couldn't make it to orbit with no payload.

@@R0nBurgundy It’s a good reminder that just because a video has a lot of views, and a lot of people agreeing with it, it doesn’t mean it’s remotely right.

Thanks. It's always interesting to compare numbers.

They will use Raptor and Starship for Mars. Musk has said that long term there will probably be a different engine, but it could just as easily be "Raptor 6.0 Ludicrous Max" or whatever. The current Raptor engines seem to be good enough to colonize Mars, assuming reliability/reuse is improved over the next few years/decades, and get to an extremely high level. They are already very good engines in terms of thrust-to-weight, efficiency, etc.

@@SpaceAdvocate thanks for the comment!

I don't think there are any practical alternate propulsion methods. There are a lot of nuclear thermal propulsion advocates but they've been saying the same thing for the last 50 years and we have yet to see a real stage. Maybe the current DARPA program will yield one, but I'm not holding my breath on performance. You might get somewhere with a cycler architecture, at least for carrying lots of stuff, but you still need to get it down to the surface at the other end.

Affect: fool around Effect: find out

You control twr by how much propellant you put in the vehicle. Higher gravity means less propellant to keep twr the same, so less Delta v.

Yes, and you would get a better answer than mine, but I think it would be much harder to explain. #3 in particular seems to break people's brains.

@EagerSpace Maybe, but this sort of analysis would (in my opinion) probably be way to much work to expect from a KZfaq video. And, ultimately, the total energy requirements, and where that energy ends up, aren't even THAT interesting. What we really care about is the payload capacity. I think your approach where you look at effective Δv requirements, and assume they scale linearly with the orbit velocity of LEO (sqrt of g) is a very natural first estimate, especially for relatively small pertubations of g+-10%.

I like your rational explanation of my laziness...

See "simplifying assumption"...

The current prototypes seem to be capable of carrying around 40-50 tons to LEO. That's pretty good for a fully reuseable vehicle. The previous record was zero. Of course, it's less than what SpaceX is aiming for. But they'll keep working on it.

Reportedly both SH and starship were only partially fueled on the last flight.

If he did, then my numbers align more closely with his.

Falcon 9 works fine. It's not great, but it works fine.

@@EagerSpace yeah, with only orbital velocity at not orbital hight. 400km orbit would be inside the earth with 10% more gravity

It could be a denser earth rather than a bigger one.

The sarcasm is strong with this one! (Yoda)

No, I didn't try to account for that.

I just worked on the Fjords.

Love the question. I'm going to be dropping a video in the next few days asking for questions from people, and if you copy your question to a comment on that video, I'll consider it. WRT second stage reuse, look at the video I just just dropped. Full reuse the way starship is doing is is ridiculously hard to do.

The earth's rotation at the equator is about 465 meters per second, and the rotation at 28 degrees (cape canaveral) is about 400 meters per second, so it's a small difference - less than 1%. That's assuming you are willing to launch to an orbit at the natural inclination of the site or higher. If the ultimate orbit you are targeting is geostationary, then launching from 28 degrees costs about 400 meters per second over launching from 0 degrees as you need to do an inclination change to get to 0 degrees.

Atmosphere is interesting (and I think very complicated) because, for a reusable vehicle, it doesn't just impact drag on ascent, it also affects various aspects of reentry: how much energy can you bleed off via drag/friction heat, how fast will this happen, how hot will things get, what trajectory do you need to use, what terminal velocity will you arrive at, and so on. And so, depending on what sorts of changes you made to the atmosphere, it seems it could potentially have quite a substantial impact on the TPS design and its mass (or even the extent to which a TPS, mostly-alone, is actually capable of bleeding off the vast majority of your energy during return; and, therefore, whether perhaps you'd need to lean more on rocket retropropulsion etc), which could have big implications for the launch vehicle dry mass and the overall vehicle design (which comes back and affects ascent too). At least for cases with a *substantially* thinner atmosphere, my impression is that ascent would be a little bit easier, but then those gains would be small in comparison to the problem on return of "how the hell am I going to get rid of all of this energy?!" Mars landings are very difficult due to its thin atmosphere: just to land a 1-ton rover, you end up needing very elaborate multi-step techniques involving e.g. an ablative heat shield, followed by a GIGANTIC supersonic parachute, ultimately followed by quite a bit of expensive powered descent. (And granted, the Mars examples we have all involve coming in at interplanetary-rather than merely orbital-velocity; and they're also pretty mass-limited overall for what measures they can reasonably employ for entry, due to not being a giant, orbitally-refueled vehicle; but still, the thin atmosphere makes EDL a substantial pain, I believe mainly because it simply limits how much energy you can get rid of passively via drag techniques.)

Interesting question. Thinner atmosphere changes the reentry heating profile and I'm not sure how.

I'm confused. I thought the Starship was more efficient for fuel to payload. What's the point, then?

@@TimJSwan The point of Starship is that it's fully reusable, and also a capable Mars transport vehicle? I don't know that I understand the question.

​@@TimJSwan Cheap propellant is cheap. If they can fly Starship for even $10MM of props and get Booster and Ship back, that likely costs less than expending a F9 upper stage. It should cost much less, to orbit 8x the payload.

@@TimJSwan No - it uses way more fuel. It's based on the fact that fuel is cheaper than rockets, and that by throwing more of the former at the problem, you can brute force the rocket equation.

The rocket itself is only 6% of the total weight. 90% is fuel, 4% is payload.

Neat to see how super wrong I was. I did see that you missed something, Starship coming in hotter and needing to land with more mass and not just talking about the landing burn, but the actually weight of reinforced joints and landing gear (flaps and thermal insulation) That would more than chip away at that 4% payload.

The factor applies to the whole vehicle and that would include reentry structural requirements since those influence the earth gravity Delta v. I have no idea how the higher gravity actually influences reentry. The factor could be higher or it could be lower.

My estimate is 4 percent.

Yes and yes. But the answer is directionally correct she is good enough to understand why full reuse is such a pain.

Less area for a given mass may mean higher re-entry heating. I have a video where I talk about stoke. It's not clear if their design works at all, and starship is ultimately designed for Mars.

@@EagerSpace I think the basic idea behind the landing capsule design was less area exposed and the hot air escaping in a way the upper part doesn't get hit by the hot gas. I suppose it is a kind of simple concept because it is used so much for reentry. Probably some kind of automatic flight stabilization too. Reminds me on some kind of roly-poly or wobble doll.

I'm very interested in seeing what Neutron will be like because Rocket Lab is the master of carbon fiber. I think the performance is going to surprise a lot of people. I think carbon would have been a disaster for starship. Starship is really easy to change because you can quickly modify a stainless steel design, but carbon fiber requires new molds and that's a ton of work. There's also the transportation aspect - Starship is hard enough with the factory just down the road from the launch site, and their original plan was to build starships in LA and then ship them to Boca Chica. No way would that work. I'm not excited about hydrogen for reusable rockets; the second-stage tanks are so much bigger so you are adding a lot of dry weight to the system.

The advantages of hydrogen quickly disappear when the entire ship needs to be returned, huge tanks would increase the diameter of an already thick ship, along with its mass, which cannot be discarded, carbon fibre not good for cryogenic fuel and not good for re-entry and reuse

Yes. It's also *really* hard to build high thrust hydrogen engines.

You could. I think the big questions are: 1) How much heat shielding do you need on the second stage? 2) Where are you going to recover it? #1 probably isn't that bad, but you probably can't get away with just the stainless steel. #2 is the pain. You basically have the same problem that Vulcan has with first stage recovery. There's no way you can afford the cost of bringing it back to the launch site, so you will need to land it downrange, which puts you back in the drone ship business which you would like to avoid, especially because it's going to be much farther downrange the Falcon 9 first stages land - you'll be out thousands of kilometers, maybe even over other continents.

@@EagerSpace Simple. Make it a horizontally landing stage and attach some jet engines to carry it home.

Pretty sure the mass cost of carrying jet fuel plus jet engines makes this worse than the two-stage version.

Pop quiz today. Put your books under your desk and I'll hand them out. You have 15 minutes.

Both the third and fourth flight got to slightly below orbit with several tens of tons of propellant left over. You'd need to burn around 5 tons of propellant to enter orbit, and the remainder of the propellant could basically be replaced with payload. The 40-50 tons figure from Musk seems reasonable going by what we can see on telemetry.

The current set of flights were reportedly only partially fueled so that they got the trajectory they wanted. But yes, they clearly aren't where they want to be yet.

Yes. That is the current state of the starship prototype.

This is completely wrong. The percentage will change with the size of the vehicle. Bigger vehicles are generally more mass efficient. Twice the size might give four times the payload, or more, or less. It depends on the specifics. Regarding Starship, the changes between versions are not just to make the vehicle larger. There are also changes like integrating the hotstage ring, removing heat shielding on the engines (as the engines will be more robust), increasing thrust-to-weight on the engines, shaving off excess weight all over the place, etc. The current version of Starship is very unoptimized. SpaceX will focus on optimization for the next few versions, once they have a minimum viable product.

@@SpaceAdvocate they did say the trust would increase, so I guess there would be some improvement although I don't know how much . How does increasing size increase efficiency?

@@m.c.4674 One basic thing that increases mass efficiency is that most of the mass is in the surface of the vehicle. This means that the mass of the vehicle is strongly correlated to the surface area of the vehicle, rather than the volume. As an example, the formula for the circumference of a circle is 2 * pi * r, while the formula for the area is pi * r ^2. As you increase the radius of the circle, the area increases much faster than the circumference. This is the same for the volume of a cylinder, as well as many other shapes. The volume increases faster than the surface area, as you increase the size. As an example, if you have a 9 meter diameter, 20 meter tall cylinder, and double it to 40 meters, the volume goes from 1272 cubic meters to 2544 cubic meters, or an increase of 100%. While the surface area goes from 692 square meters to 1257 square meters, or an increase of 82%. Other things that increase efficiency for larger vehicles is that some components don't need to be any bigger for a larger vehicle. Like the avionics. You can often use the exact same avionics for a larger vehicle than for a smaller vehicle. There are many components like this, which do not need to be any bigger for a larger vehicle. One big example for Starship specifically is that it's unlikely that the future version will have a bigger payload fairing. The current payload fairing is plenty big, and can accommodate a 100-200 ton payload. This is like 40% of the length of the Starship upper stage which doesn't have to change at all.

@@SpaceAdvocate but it is increasing in length , even if it wasn't drag also increases with diameter , about the same as volume. Computer , sensor in a ship this big is already microscopic compared to the ship . And structural support will need to increase as the mass increases. I'm a space x fan , I just want actual proven numbers on the payload that starship new raptor engine can lift to space . 10% more thrust , could be 10% faster fuel intake, or preferably a 10% increase in the speed the gas is being released (I think they call it bar pressure, something like that). Let's say it is 10% more bar pressure, okay so per tonne of fuel 10% isn't used , the rocket is pretty much entirely fuel , so 4500 tonne of fuel , so then the ship will have a remaining 450 tonne of fuel. If 4500 tonne of fuel can only life 1% of payload to space and 450 tonne of fuel is 10 times less , then that 10% increase in bar pressure would total to 1.1 % of mass being payload. So a payload increase of 5 tonne totaling 55 tonne , version 2 I think is about 10 percent longer so that another 5 tonne, so total tonnage of version 2 would be by my approximate 60 tonne. Version 3 is still completely hypothetical, they may never achieve this , or even want to do this , 33 engines and not one ever blowing up, yeah see you in 100 years .those engine shields will remain. I'm am biased in that I don't think starship should do any mission outside low earth orbit. I don't think any of the current rocket engine cryogenic fuel or not is efficient enough to sustainably go to Mars , moon etc.. Ion thrusters are simply better , rockets release gas molecules in slow motion in comparison to ion thrusters. Starship has the payload capacity to low earth orbit to build a true starship, one power by ion thrusters.

@@SpaceAdvocate when it is low gravity or space , using rockets is kinda not good at all . Ion thrusters typically have specific impulses in the range of 2,000 to 5,000 seconds. This is much higher than the specific impulse of chemical rockets, which are typically in the range of 200 to 400 seconds

No, it's more like 130 tons. 75 tons might be possible for an expendable version.

There are all sorts of numbers out there. I've used 100 in the past, but 130 gave me reasonable estimates with the rest of my model. If you use 75 the quoted payload figures are way too low.

No, that's not how the rocket equation works. Your mass at stage shutdown is unchanged. In terms of the required liftoff thrust, you are correct that it would be equivalent to adding 10% extra mass, but what happens after liftoff follows the rocket equation.

Yes i was thinking this too. You would need extra rocket engines to lift off adding way more mass along with a stronger frame to deal with the extra thrust. F9 produces 7.6MN of thrust and at lauch gravity pulles with 5.7MN giving a positive thrust of 1.9MN with one G. If everything now weights 10% more gravity will pull with 6.3MN leaving only 1.3MN of thrust a 32% loss. This effect componds gravity losses as you are accelerating a lot slower now.