/sci/ - Science & Math

>you can launch a kero-LOX rocket and re-land the first stage in an orbital mission without sacrificing all of you payload

LMAO muskfags are so retarded, the aerospace industry declared that impossible in the 90s so it can never be done. LOL get a grip, just keep buying atlas launches for 300 million goys nothing to see here

>>7994132
>Image Credit: Reddit
>b2reddit

>>7994156
r/SpaceX are the source of all muskfags even on /sci/

First of all get an image that doesn't look like trash.

>>7994132
>taller than the Apollo Saturn V rocket, and some 50 percent wider than the launch vehicle that sent men to the Moon
So you think that the rocket to go to Mars ought to be smaller than the one that went to the moon?
>>7994149
>the aerospace industry declared that impossible in the 90s so it can never be done
I want you to read this statement again and realize how stupid it is.

>>7994149
>thinking that something that hasn't been done before is possible

You'd better stay out of the AI threads.

>>7994166
I'm not saying the dimensions are wrong I'm saying that Musk will never be able to pull this off.

>>7994212
Can you provide reasons to support your argument, or do you expect people to just trust the intuition of an anonymous know-nothing?

>>7994216
Uh basic logic? The Saturn V took the collective effort of the world's richest country spurred on by Cold War paranoia and he wants to build a rocket 3x the size with no multi-billion dollar budget, no mass public support and no highly concentrated technical expertise. Musk is just one guy, He doesn't have command of all the best engineers in the country, only a handful of nerds know or care about his Mars plans so even if he managed to ask Congress for funding once that got pitched to voters it would be laughed the fuck out. What he is claiming is like if Apple randomly decided to say they were going to build a navy to match the USN. Rich as their company is that's way beyond the capabilities of any private organization. There are some things private companies just can't do. The Saturn V was hard as fuck to build, even today SLS is a tough job for NASA, even if you are going to predictably come out with "SLS is inefficient" the fact is superheavies are hard as fuck to build and he wants to build some super duper heavy right off the bat. Anything that big if it's even feasible can only be an international effort.

What's with the fetish for killing off the only real hope that fans of space exploration have had in decades? That sort of hope and hype does more than you can imagine for inspiring kids to stick with school and become physicists and engineers.

Pessimism disguised as realism is cyclical poison. If you want to make sure that humanity continues its current dog-slow pace of progress in that sector and never amounts to anything, being hopelessly negative is a surefire way to do that.

He might pull it off. He might not. Nobody's losing anything if he does, and if he doesn't we haven't lost anything either. We only stand to gain. Why the hate?

>>7994278
Lol fuck /sci/. you literally every new tech I post on here gets trashed to hell, Fusion, personal aerial vehicles, electric cars, driverless cars, Skylon yet with SpaceX suddenly /sci/ goes full on "I want to believe"

I support Musk's plan to send people to Mars I thought he was going to take a sensible approach of sending 4 people in one Dragon on a Falcon Heavy or assembling the spaceship in orbit over time with his Falcon Heavies if he wants to send that many people in one go. Building a rocket that big is just nuts.

>>7994299
Well, I think there's something to be said for a "go big or go home" sort of mentality. It sends a message that he's not fucking around, and that has a profound psychological impact on people.

It's incredibly risky but if it works, it'll accelerate the schedule several fold over taking a more progressive approach, and that's exactly what Musk is after. He wants a thriving martian colony to exist no later than the 2050s-2070s where there otherwise might be a tiny research outpost if we're lucky.

>>7994166
>>7994176

Not him but boy you got baited.

>goys

>>7994262
>The Saturn V took the collective effort of the world's richest country spurred on by Cold War paranoia
>ENIAC took the collective effort of the world's richest country spurred on by Cold War paranoia
Technology marches on. Saturn V wasn't done in an efficient way, anyway. The engines were all hand-welded and brazed together. They were just in a panic to get it done as quickly as possible, fuck cost.

The BFR might cost no more to build than Falcon Heavy (which is something in the neighborhood of a $50 million dollar project). Remember that Merlin was the SpaceX engine team's first effort, and it was rather rushed. They'd never put an engine into production before. Besides, there's been a decade of progress in production technology and material science.

With this benefit of experience and progress, Raptor might just come in a few parts out of 3d printers and similar machines requiring little input of labor. Merlin 1D was cheaper and easier to produce than Merlin 1C, while also being more powerful and reliable. Raptor could well end up being cheaper and easier to produce than Merlin 1D, on top of being much more powerful, with a higher specific impulse, longer life, lower maintenance, and other benefits.

>>7994400
Double dubs speak truth. The notion that we hit the apex of launch technology or came anywhere near it in the 60s is hilarious. There's still vast room for improvement, and if this group of newcomers continues at their current pace, in a decade the very suggestion of using old codger rockets for any kind of launch will be laughed at.

>>7994132
>Bigger than a Saturn V
>All RP-1
That's a shitload of impulse. What are you lifting, the goddamn Titanic?

>>7994418

I think the scale of that drawing is misinformed and the real height will be lower.

>>7994418
A martian power and fuel production plant.

>>7994418
Secret Mars SuperEvil Muskbase aint light, anon.

>>7994454
>soviet
you mean german

>>7994418
Enough equipment to construct a self-sufficient martian base and some extra space so those riding don't go nuts on the way there.

>>7994299
>with SpaceX suddenly /sci/ goes full on "I want to believe"
What's wrong with you? /sci/ argues about everything, including SpaceX.

If you're joining the argument and getting jumped on, it's probably because you're taking a stupid position.

>I support Musk's plan to send people to Mars I thought he was going to take a sensible approach of sending 4 people in one Dragon on a Falcon Heavy
>Building a rocket that big is just nuts.
First of all, OP's article is mostly garbage, and so is the image. While the diameter may be about right, the height seems improbable. And why is there a radiation warning sign on the top?

Now, what would be nuts is firing the design team and just continuing to operate Falcon 9 and Heavy until SpaceX goes out of business, or trying to go to Mars with an underpowered rocket.

Falcon Heavy is only able to throw a fully-loaded Dragon to Mars in expendable mode. Even if you could just put four guys in it and have them live in a capsule for the six-month trip (which might be possible, but wouldn't be easy or a pleasant way to travel), that's about $40 million per person, just to transport people there. You certainly couldn't send everything they needed to live there with them in the capsule. So maybe you can land 2 tons of cargo per Dragon launch. You're going to need at least one per person, so now you're talking about over $200 million per person, just for transportation. That's no way to build a colony.

The BFR is a fully-reusable rocket. Full reusability costs about 2/3rds of performance even just going to LEO. So at minimum, you want to go bigger than Falcon Heavy, or you're going to get less performance than a Falcon 9, which is a bit undersized even for satellite launch.

Now, where do you stop making it bigger? Falcon 9 was sized to fit under Interstate overpasses. BFR will likely be as large as is practical to handle with barge transportation.

Anyone can draw up proposals for big-ass dildos. I'll consider their plans viable when they come up with some technical plans that show it can be light enough to get into space under it's own thrust and strong enough not to collapse under it's own fuelled weight.

>>7994418
It's not RP-1, it's methane. The high-Isp staged-combustion LOX/CH4 engines should offset the relative disadvantage of not using a LOX/H2 upper stage.

You have to remember that BFR is supposed to be a fully-reusable vehicle. As such, there are significant performance penalties for going to higher orbits because of the added mass on the upper stage.

A 200-ton-to-LEO rocket might seem like crazy overkill that will never get used for the satellite market, but if it doesn't just take them to GTO, but circularizes them in GEO, and then returns to Earth for reuse, then the payload won't be all that much bigger than GEO comsats are now. The larger mass allowance could also significantly reduce costs and increase capabilities.

I think comsat companies would be happy to use this big rocket.

>>7994509
>or trying to go to Mars with an underpowered rocket.

With the competency in modular spacecraft design we've gained from the ISS, there is no longer any reason to rely on big ships. $/kg to LEO is the only metric that matters anymore.

Can't we make a railgun rocket launcher that fires a laser to ionise the air beforehand, creating a short-lived vacuum tunnel?

>>7994627
/sci/ is an 18+ board.

>>7994149
>LMAO muskfags are so retarded, the aerospace industry declared that impossible in the 90s so it can never be done.
No-one deemed it impossible. They just thought it wouldn't make sense. And they kinda still do, despite spacex' overhyped stunts.

>>7994615
>With the competency in modular spacecraft design we've gained from the ISS
Skylab was a one-piece space station of about 70 tons, made with 1970s technology. It was put up in one launch and provided about 350 cubic meters of pressurized volume and could support a crew of 3. (it had few crew missions and splashed not because of any inherent fault, but because NASA was shifting to a shuttle-only manned program, and the shuttle wasn't ready on time)

ISS is a modular space station of about 420 tons, made with 1990s technology. It was put up in thirty major component launches, provides 900 cubic meters of pressurized volume, and can support a crew of 6.

If anything, ISS demonstrates the gross inferiority of modular spacecraft design, and the importance of large payloads. And it's not even a structure that has to withstand a departure burn or aerobraking.

>$/kg to LEO is the only metric that matters anymore.
Single-launch payload size also matters, but I think the floor on $/kg is lower for a large, frequently-flying fully-reusable vehicle than it would be for a small one. Fewer launches = less organizational overhead.

>>7994132
even LA-NTR seems less crazy than that:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA426465&Location=U2&doc=GetTRDoc.pdf

>>7994149
Kek /sci/ is easy to b8

You're doing God's work anon

>>7994132
>For a number of reasons, SpaceX has opted for cryogenic liquid methane as the MCT fuel:
> *Methane can be manufactured on Mars from subsurface ice and atmospheric CO2. This can dramatically increase the payload that can be delivered to Mars for a given launch because the fuel for the return to Earth will not need to be transported to Mars.
> *Methane is cleaner burning than kerosene (RP-1) so less engine maintenance will be required between flights.
> *Methane is denser and less technically challenging to handle than liquid hydrogen.
> *The boiling point of liquid methane and liquid oxygen are nearly the same, reducing thermal insulation requirements between the fuel and oxidizer tanks.
>* To reduce the size of the booster, liquid methane can be further “densified” by chilling it to almost the freezing point.

So, apart from meme reasons (i.e. reusability and muh mars colonization), there is no advantage to methane over LOX/LH2, the only civilized rocket fuel?

>>7994714
I don't think this was even supposed bait.
It's just that /sci/ sometimes fails to detect basic sarcasm.

>>7994757
Are you baiting? How on earth is true reusability (given that it's actually achieved) a meme? It reduces launch costs to a fraction of a fraction of what disposable launches cost, both in time and finances.

If we're talking "reusable" like the shuttle was, yeah, it's a fucking joke and a half. But what if it's not? What if the claims end up panning out?

>>7994768
One of the basic principles of lightweight structures is that they are designed at the edge of failure. This is true for aircraft, but is much more true for spacecraft. For aircraft, the driving factor for reducing the amount of material is cost. It's easy to over-design aircraft by making it more expensive. Put on bigger engines than needed give you power to get out of any aerodynamic difficulties. More lift surfaces give you greater lift and stability than needed. We're able to push the envelop of aircraft and make them reliable by volume. The enormous number of flights per aircraft means we can thoroughly test the design and safety of the aircraft with very low overhead when amortized over all flights, and we learn and standardize across the many, many flights of many aircraft. It's easy and reliable because you can over-design and optimize by volume of flight.

Space doesn't have this luxury. First, you can't really over-design a rocket. It can be over-designed for a given payload need, but the added structure and material adds more risks to the flight, not less. The conditions they must operate change quickly from 1 atmosphere of pressure, to zero, with massive air friction, high temperatures, large vibration, and a wide range of very dangerous materials under dangerous conditions moving very quickly internally and externally. Safety margins are thin. Redundancy and safety adds weight which requires more propellant which makes it less safe, and so forth. The rocket equation is one of diminishing returns with mass ratio. Adding 1 kg of dry mass can require 10 kg of fuel, which requires a bigger tank and greater acceleration to even lift off. It is physics that makes space flight hard.

>>7994783
On top of this, the number of launches is still in its infancy compared to aircraft flights. It isn't the number of years that matter; it's the number of flights. The more flights we have the safer it should get, and the more standardization the cheaper the overhead, and cheaper the costs of launch, increasing the number of flights we can afford. But it's still going to be near critical design on the edge of failure, even then. We'll just be more confident and more reliable. But still hard, and still far, far more sensitive to any errors or changes to condition.

It is the sensitivity of spaceflight that makes space hard, where catastrophic failures result from minor errors, imperfections, or unexpected conditions. I don't expect we'll find ways to change the mass of the Earth or gravitational constant any time soon, or remove that annoying atmosphere, but you should never underestimate the next generation and their entrepreneurial spirit.

tl;dr: reusability is a meme because rockets use roughly the same materials and the same manufacturing techniques than aircrafts, but have to sustain incredibly higher stresses and strains, and because there's isn't nearly enough launches worldwide to make it viable.

>>7994757
>meme reasons (i.e. reusability
Reusability isn't a "meme reason".

>there is no advantage to methane over LOX/LH2
No, setting reusability aside, these matter quite a bit:
> *Methane is denser and less technically challenging to handle than liquid hydrogen.
> *The boiling point of liquid methane and liquid oxygen are nearly the same, reducing thermal insulation requirements between the fuel and oxidizer tanks.
The main trouble with liquid hydrogen is that the density is very low. So while its specific impulse is better than just about any other fuel, its density impulse is worse than any of its challengers.

This would mean bigger, more expensive stages to carry the same payload even if hydrogen didn't also have a problematically low boiling point and unfortunate chemical properties.

The reason people sometimes use hydrogen upper stages is that this makes the lower stage smaller. However, this is an iffy way to save money.

Hydrogen lower stages are generally considered a foolish idea. Delta IV is about the only time this has been tried, and it has been generally unsuccessful, and was only kept around as a backup option to Atlas V.

>>7994783
>>7994788
holy fuck man

>>7994788
That makes perfect sense but it doesn't register as a valid reason to not even try. And really, I think SpaceX is approaching this the right way: they've been iteratively designing toward reusability using missions that don't require it. They're not coming out of nowhere with crazy claims; this is something that they've been (and still are) gradually working toward.

And who knows, maybe they will never get to the point where they have 99% reusability, but if they can achieve a 50% success rate that's going to have a serious impact on costs.

Whatever the case it's still worth a shot. There's literally nothing to lose for trying.

>>7994132
>may require 30 engines
>could be enormous
nice qualifications hedging there

>>7994418
Dreams.

>>7994788
>reusability is a meme because rockets use roughly the same materials and the same manufacturing techniques than aircrafts, but have to sustain incredibly higher stresses and strains, and because there's isn't nearly enough launches worldwide to make it viable.
Thank you, /sci/'s bubble is gonna burst soon.

>>7994801
>They're not coming out of nowhere with crazy claims
Thier literal words:
>"We are going to make a big fucking rocket, that's right that's the name, big fucking rocket 3x the size of Saturn V and use it to blast 100 people to Mars to start a colony"
This is /x/ tier now. Wouldn't be surprised at this point if the fuel tanks will actually be filled with Kool Aid.

>>7994801
Worth noting too that by the end of the year, SpaceX will be launching bi-weekly. That's nowhere near airliner levels, but it's a significantly faster cadence than prior organizations have had and it should be quite helpful for gathering data points and iterating.

>>7994788
>rockets use roughly the same materials and the same manufacturing techniques than aircrafts, but have to sustain incredibly higher stresses and strains
Bullshit. Rockets accelerate in straight lines. All of the strain is along a single axis that the thrust is directly in line with. That's not inherently (let alone "incredibly") harder to deal with than holding a big plane up on wings in rough weather.

As for atmospheric entry, that's a solved problem: you just come in behind a heat shield. If you make a ballistic entry, and you land propulsively, all the stress is still on that one axis. The trouble the shuttle had was that they insisted on making it a spaceplane, and having a complex functional interface with the superheated air. So they couldn't just have a heat shield. They needed heat-shielded wings and control surfaces. That's much harder.

>there's isn't nearly enough launches worldwide to make it viable.
Chicken-and-egg. It's not that people don't want more launches, it's that they're too expensive.

Anyway, the real reason we don't have cost-effective spaceflight in 2016 has nothing to do with the technical challenges and everything to do with government hostility to private spaceflight everywhere until the early 2000s, when the US government became friendly to it. In terms of independent private effort, we're still in the Wright Brothers days of spaceflight: just a decade or so of people being allowed to try.

Orbital rocketry is inseparable from ICBMs. Even without carrying nuclear weapons, those can hit any target in the world from any place in the world. Anyone who can launch a satellite could destroy the White House, or any stationary target of similar importance, at will. All governments are uneasy about anyone else having that capability, but for whatever reason, the US government decided recently that it wanted a competitive private launch industry. So now we've got SpaceX, Blue Origin, and various others.

>>7994864
ZOMG! 3 times the size of Saturn V!

Can you even imagine a private company in the 2020s outperforming government bureaucracy from the 1960s in a high-tech field?!
>This is /x/ tier now.

>>7994883
Aerospace doesn't scale up linearly you mongoloid. You can't build a rocket that big full stop.

>>7994872
No heat shields just sucked. It had nothing to do with control surfaces, tiles failed everywhere
And rocket engines are under much more stress than jet engines

>>7994891
>Aerospace doesn't scale up linearly
Okay, you tell me what "doesn't scale up linearly" in a rocket that makes it impossible to just make it fatter until it's three times as massive or three times as large in volume as a Saturn V.

Keep in mind that the source of OP's image is given as "Reddit", and we're talking about statements coming out of SpaceX, not sketches and commentary from random standers-by.

>>7994905
>you tell me what "doesn't scale up linearly" in a rocket

fluid viscosity

>>7994897
>No heat shields just sucked. It had nothing to do with control surfaces, tiles failed everywhere
They needed it to glide to a landing, so they couldn't just design the heat shield to be a good heat shield. For instance, they couldn't use ablative shielding anywhere, because uneven ablation could mess up the flight characteristics.

>And rocket engines are under much more stress than jet engines
Not really. They're just different. The temperature's higher, sure, but on the other hand, it's only higher in the combustion chamber and nozzle, so there's no reason you can't put in whatever cooling you need.

While jet engines typically use superalloys for high-temperature components, people are talking about using ordinary aluminum for combustion chambers and nozzles. Copper has been quite common in the past. This is because they use things like regenerative cooling and curtain cooling (spraying a layer of fuel without oxidizer in rings at key points, so it forms a curtain of much cooler, often opaque gas, which may even lay down a layer of insulating soot) together, so even though the temperature in the combustion chamber is very high, the temperature of the combustion chamber wall is kept within reasonable bounds.

Simple fiberglass has been used in the past, for ablatively-cooled combustion chambers and nozzles. These take some refurbishing between uses, but it's just replacing a layer of fiberglass. Not much compared to the elaborate maintenance of some high-performance jets.

>>7994911
You're not going to get away with just waving your hand at a general concept. I already think you're an idiot.

Explain specifically how the scaling effect of fluid viscosity allows a Saturn V but somehow forbids a rocket either three times as massive or having three times the volume.

Bear in mind that we're not talking about larger engines, but simply a larger number of similar-sized engines.

>>7994905
> what "doesn't scale up linearly" in a rocket

The rocket equation.

>>7994944
first, fluid properties not scaling with size is a fundamental problem in aerodynamics and engineering in general.

viscosity effects boundary layers, friction, heat transfer, and a host of other parameters in hull design. this is just from an aerodynamic standpoint.

>Bear in mind that we're not talking about larger engines, but simply a larger number of similar-sized engines.

now, go take a look at gas dynamics and rocket nozzle geometry and see how the scaling there is non linear. MORE ENGINE is not a design philosophy.

and finally, go read up on modern material limitations. yield strength doesn't fucking change with size m8.

i could keep going with all the "non linear" factors in rocket design, but the point is that in order to get something that big made would take massive leaps in technology.

this is all undergrad fluid mechanics, so i'm not going to spoon feed you equations.

>>7994950
There you go again, just waving your hand at a general concept you clearly don't understand.

delta V = exhaust velocity * ln(final mass / initial mass)

There's no absolute mass factor, only a mass quotient. The rocket equation certainly scales up linearly in respect to rocket size for a fixed delta-V (destination) and exhaust velocity (Isp).

>>7994956
>i'm not going to spoon feed you

Low-quality internet people think they win the argument whenever the other party refuses to spoon feed them. If you don't provide the information then it is assumed to not exist, and if it is politically inconvenient for them then you are just a 'shill' spreading 'disinformation'.

>>7994961
>thinks real-life rocket design is the same as in KSP
>accuses others of hand waving and shallow understanding

>>7994670
SpaceX's rocket is already a tenth of what the old rocket costs, and they can fully reuse it

>>7994956
>viscosity effects boundary layers, friction, heat transfer, and a host of other parameters in hull design. this is just from an aerodynamic standpoint.
Nope, nope, nope. This is still vague hand-waving. Yes, the aerodynamics of a rocket with three times the cross-sectional area are going to be a little different, but the aerodynamics of a pushing a cylinder through the air by brute force are pretty trivial.

You haven't identified any fatal flaw.

>>Bear in mind that we're not talking about larger engines, but simply a larger number of similar-sized engines.
>go take a look at gas dynamics and rocket nozzle geometry and see how the scaling there is non linear.
What are you fucking talking about? We're talking about having a rocket engine, and putting another rocket engine beside it. The gas dynamic interaction between them is negligible.

Don't tell me "go look at". This is not a situation where you're a respected person being asked for help to understand something. This is a situation where you've said something that appears to be really fucking stupid and are refusing to produce a specific argument in support of it.

>i'm not going to spoon feed you
In other words, you have no idea what you're talking about, you just think you can bluff your way through this.

>>7994979
>This is still vague hand-waving
REYNOLDS NUMBER YOU FUCKING RETARD

>>7994979
>but the aerodynamics of a pushing a cylinder through the air by brute force are pretty trivial.

>>7994989
Isn't it clear by now that this is not going to work?

You said something extremely stupid, now you're just wildly googling for concepts related to aerodynamics and rocket propulsion, and referencing anything that seems like it might be relevant, waving your hand at it, and hoping that I'll be intimidated because you've pulled out some terminology, even though you plainly don't understand it yourself.

This is an anonymous forum. What's wrong with you, that you have to try and deceive other people into believing claims based on nothing? What is it that you feel like you're gaining? Is your life so pathetic that this is the most important you can make yourself feel?

>>7994996
Only a brainlet would struggle at solving the Navier-Stokes equations.

>>7995008
>Navier-Stokes always has simple analytical solutions like the ones taught to me in undergrad aero eng
Yeah of course we can just work out the aerodynamics of a fuckhuge rocket barreling through the atmosphere at thousands of miles an hour on paper just like in school. No need for powerful supercomputers running complex simulations that sometimes fail anyway because not even computers can handle turbulence.

>>7995001
lol, w/e dude. you are operating from a position of ignorance. you don't know what any of what i mentioned means but you dismiss it as untrue. i'm pulling it straight out of an undergrad textbook so if you think i'm bullshitting take it up with Munson and Young.

ITT: SpaceX fanboys
Blown
The
Fuck
Out

>>7995008
>he thinks our current model of fluids is some neat little autistic math puzzle

lol. its a patchwork mess of empiricism where nobody is really on the same page, and everyone has different models. CFD has become almost an intuitive art at this point.

>>7994996
>but the aerodynamics of a pushing a cylinder through the air by brute force are pretty trivial.
They are. Look at rockets. They come in all kinds of shapes, which have little do do with aerodynamics other than a general interest in minimizing cross-sectional area. Sometimes Falcon 9 launches with a 3.9-meter Dragon on top, sometimes with a fat 5-meter fairing.

It doesn't make a huge difference, because they're just pushing it through the air by brute force, and the air gets thinner as they gain altitude anyway. The drag losses are small compared to fighting gravity and accelerating to such high speed. They're mostly worried about the maximum dynamic pressure the structure can withstand.

If the maximum thrust would accelerate a rocket to a speed it can't take at a certain altitude, they have to throttle down or shut off some engines to reduce acceleration. This slightly reduces payload because slowing the acceleration increases gravity losses. Not a big deal, just something that has to be taken into account.

Waving a hand at the aerodynamic differences of a larger-diameter rocket as if they're necessarily going to be prohibitive is a very convincing demonstration of total incomprehension of what's going on in a rocket launch.

>>7995021
>lol, w/e dude
I'm not the anon you're responding to but good god you sound like an enormous faggot.

>undergrad textbook
No one but retarded high schoolers are going to be impressed by that.

For the record I hate Muskfags but you're even worse.

>>7995036
>The drag losses are small compared to fighting gravity and accelerating to such high speed

>what is compression at high mach numbers

>what is two phase flow

>what are turbulence induced vibrations

>what are stagnation points


holy shit freshman. you think muh drag coefficient is all they care about when they do an aerodynamic analysis?

>>7995043
>No one but retarded high schoolers are going to be impressed by that.

i figured an undergrad text would be an accessible resource for someone of your limited intellect. i wasn't trying to impress you :^)

>>7995021
>you dismiss it as untrue
I dismiss it as irrelevant. Because you're a moron who's gesturing vaguely at things that don't matter, and pretending that they make the case for your highly specific claim, in some way that you refuse to explain.

You still haven't given any reason why Saturn V works, but a rocket specifically 3 times the mass or volume can't.

>i'm pulling it straight out of an undergrad textbook
Yeah, that sounds about the level you're operating on. Congratulations on book-having. Did you torrent it specifically for this argument?

>>7995045
Nah man. You just, like, throttle down if the pressure gets too high.

>>7995049
>Did you torrent it specifically for this argument?
would it matter? if you looked at it yourself you would see why i'm right. you are arguing with a book here man, not me.

>>7995048
Serious question, why does any of this matter to you? Its clear you don't work in the space launch industry so why spend so much time on this topic when you could be better applying your time to something useful?

No one cares what some cuck on /sci/ thinks.

>>7995048
You're turning me on anon. Are you a trap? Want to meet up so I can fuck your little ass?

>>7995021
This image perfectly sums you up. I get it you want to go to Mars but believing in pipe dreams will only set you up for disappointment. I believe SpaceX can do it but by slowly assembling an ISS style spaceship in orbit and even that will take years and many billions. This fuckhuge rocket is just full retard.

>>7995062
What's your educational/employment background anon? Not looking to troll just curious of your level of expertise in this area.

>>7995049
>You still haven't given any reason why Saturn V works, but a rocket specifically 3 times the mass or volume can't.

no no no here buddy. you asked here >>7994905
why rocket design didn't scale linearly. and i told you why it doesn't scale linearly.

if you took the 5 minutes to go look at any of the governing equations regarding rockets you will see many, many, completely non-linear relationships.

>>7995076
He's just going to keep claiming justifiable ignorance until you explicitly state those equations.

>>7994842
Don't let your memes be dreams

>>7995076
>>You still haven't given any reason why Saturn V works, but a rocket specifically 3 times the mass or volume can't.
>no no no here buddy. you asked here >>7994905
>why rocket design didn't scale linearly. and i told you why it doesn't scale linearly.
Uh... okay, let's take a look at >>7994905
>Okay, you tell me what "doesn't scale up linearly" in a rocket that makes it impossible to just make it fatter until it's three times as massive or three times as large in volume as a Saturn V.
>you tell me what "doesn't scale up linearly" in a rocket that makes it impossible
>you tell me what ... makes it impossible

So let's look at it in context, this is what it was replying to: >>7994891
>Aerospace doesn't scale up linearly you mongoloid. You can't build a rocket that big full stop.
>You can't build a rocket that big full stop.

So are you going to try and act like your reading comprehension was just so poor that you thought I was saying that everything aspect of rocket design scales up exactly linearly, rather than that I was rejecting the idea that nonlinear concerns forbade the construction of a rocket three times as big as Saturn V?

Do you understand how much MORE idiotic this makes you seem?

>>7995099
...and while we're at it, let's look at the exchange:

>>7994905
>Okay, you tell me what "doesn't scale up linearly" in a rocket that makes it impossible to just make it fatter until it's three times as massive or three times as large in volume as a Saturn V.
>>7994911
>fluid viscosity
>>7994944
>Explain specifically how the scaling effect of fluid viscosity allows a Saturn V but somehow forbids a rocket either three times as massive or having three times the volume.
>>7994956
>the point is that in order to get something that big made would take massive leaps in technology.

So here we are: plain as day that you were talking about whether a rocket three times as big as Saturn V can be built.

>>7995099
okay fag, if you want to claim you weren't being hyperbolic, NOTHING is impossible. anything could happen at anytime if we are really dealing in absolutes like that.

i was trying to be reasonable and assumed impossible meant prohibitively difficult.

I wonder who's more pathetic. The troll taking time out of their day to bother anonymous people on the internet, the people who don't know how to recognize a troll, or me creating this post.

>>7995126
its only one guy on 4chan

>>7995116
>i was trying to be reasonable and assumed impossible meant prohibitively difficult.
The difference between "impossible" and "prohibitively difficult" is obviously not the issue. You're just nitpicking my word choice. Everything I said works fine if you replace "impossible" with "prohibitively difficult".

>>7995126
>The troll taking time out of their day to bother anonymous people on the internet
He's not a troll, he's an idiot, who got caught being an idiot, and is flailing around embarassing himself.

>>7995073
?
Why do believe there is a massive difference between putting a 1 ton rover on mars, and putting a person?

The only thing that makes it awkward is the long travel time

>>7995138
What makes it prohibitively difficult?
Suppose they strapped 9 falcon rockets together, what physical law would mean it wouldn't work?

Why do the dimensions of the MCT indicate that it is not feasible using modern technology?

>>7995152
This thread is about putting 100 people on Mars. That's what's ludicrous. 100 man rockets are not technologically feasible.

>>7995160
This post illustrates the fundamental problem in this thread, the SpaceX supporters who we are trying to educate with basic rocket mechanics, materials science and fluid mechanics are getting all their information from KSP.

>>7995170
Just make a 5-man rocket and scale it up by a factor of 20.

>>7995170
What makes them not feasible?
If a rocket could deliver say, 200 tons to mars with refueling in orbit, then all you need is the inflatable habitat for space & something to do on the trip

>>7995174
Nothing about those things makes it "prohibitively difficult" or "impossible" to build large wide rockets.

>>7995164
We already said a million times that neither the rocket equation, the material stresses nor the aerodynamics scale up linearly but you refuse to listen. You think you can just keep adding boosters until you can take anything you want wherever you want.

>>7994165
No no no no. I'm so pissed about this "hurr it's 2016 EVERYONE on 4chan is also on leddit" meme

That's complete bullshit. Reddit is so fucking cringy and PC, most people in 4chan are such a big fucking disgrace they couldn't even try to act like reddit fags. Stop with that stupid ass evidenceless meme just because you have to compensate your shitty taste

>>7995268
Your argument would carry more weight if everything outside your neo-Nazi /pol/ hugbox wasn't 'PC' to you.

>>7995183
Materials at not at all being overly stressed
Aerodynamics of a rocket are more or less irrelevant
And the rocket equation is just about fuel fractions

>>7995183
>We already said a million times that neither the rocket equation, the material stresses nor the aerodynamics scale up linearly
Uh... it has already been pointed out and demonstrated that the rocket equation does scale up linearly in this sense. If you triple the initial mass, and you triple the final mass, with the same specific impulse, the rocket equation says you get the same delta-V. See: >>7994961

The "material stresses" only get worse as you scale up if you're making the rocket taller.

The idea that that aerodynamics of a somewhat fatter rocket would be prohibitive is laughable, and you've persistently refused to make any specific case for the aerodynamics becoming a problem as you move from the size of a Saturn V to triple that cross-sectional area.

>but you refuse to listen.
Why would anyone listen to handwaving morons?

The MCT is far from the largest rocket proposed. Nobody at NASA ever said the Saturn V is the largest rocket possible, or nearly the largest possible. In fact, there has been a great deal of discussion of larger, more powerful rockets, such as Ares V and Sea Dragon:
https://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29

>>7995323
>Aerodynamics of a rocket are more or less irrelevant

does the phrase Max Q ring a bell?

>>7995387
>>more or less
>that means exactly the same thing as "completely"!
idiot

>>7995410
Most people care when their shit explodes in midair.

>>7995446
>>Pedestrians are more or less irrelevant to highway driving.
>Most people care when they run into someone at highway speed.
idiot

>>7995459
That analogy doesn't work at all. Pedestrians aren't a normal part of highway driving. Aerodynamic stress is a normal part of a rocket launch.

>>7995470
>That analogy doesn't work at all, if we focus on an aspect that doesn't correspond and ignore the ones that do.
idiot

>>7995470
And in no way does aerodynamic stress indicate that it's physically impossible to build a rocket X meters wide

>>7994149

>>7995498
That's not bait, that's really obvious sarcasm, mocking OP for scoffing at the idea that the world leader in orbital launch technology would build the biggest rocket ever.

>>7994757
its a hell of a lot cheaper than H2
Methane is fucking pennies compared to hydrogen

>>7994944
Implying anyone on /sci/ cares

>>7994299
>Building a rocket that big is just nuts.
Why though? Thinking physically, wouldn't bigger be more efficient aerodynamically? And potentially in materials? The ratio of surface area to volume (for fuel) gets better with size.

>>7995567
I don't think it really improves aerodynamically unless they make it taller, but then the structural loads go up.

There's definitely a structural advantage as you go to thicker rockets. It's easier to work with thicker sheet metal, you have more choices of material and you have more options for reinforcing it. You can insulate the tanks better, and protect the surface of the rocket better from the elements at lower costs in mass, due to the volume increasing faster than the surface area.

>>7994757
Why is reusability a meme?

>>7995613
because the "old space" establishment insisted it was impossible or not cost effective

>>7994132
Imagine the size of the fireball if it blew up.

>>7995690

Old Spacers are incredibly angry over the sea change SpaceX's costs are forcing on the industry, and the newfound competitiveness is going to ultimately destroy a lot of their jobs. 4chan happens to be one of the few places they can anonymously vent about it.

>>7995718
This SpaceX fanboyism is just getting sad.

>>7995938
Its ok gramps, I'm sure ULA will still honor your pension.

While I agree the SpaceX fanboyism is sad, its still preferable to ULA/NASA fanboyism.

>>7995718
"Old spacers" don't use 4chan.

>>7994627
Your way of doing things anon
>build railgun
>build laser
>build rocket

Musk way of doing thing
>build bigger rocket

Elon while reading "SpaceX BTFO"-treads

>>7994132
>>The single-core booster will launch and land in a similar fashion to the first stage of the SpaceX Falcon 9. However, it may require as many as 30 sea-level Raptor engines in order to generate sufficient thrust. Consequently, it could be enormous: 49 feet (15 meters) in diameter and 394 feet (120 meters) tall—taller than the Apollo Saturn V rocket, and some 50 percent wider than the launch vehicle that sent men to the Moon.

The people who made that illustration needs to be beaten. If the MCT would be made to the dimensions posted in the article, it would be a measly 30 feet higher than the Saturn V, not double its size
Pic related, and yes i such at making drawings.

>>7996272
Suck* i cant fucking spell either

>>7994783
>>7994788
I'm so saving this for later reuse. This is literally instant Muskboi repellent.

>>7994864
AND WE'RE GONNA HAVE MEXICO PAY FOR IT

>>7996405
>ignores the fact that it got replied to and debunked almost immediately

>>7996411
Le me guess, this >>7994872 is probably what you call "debunking". Don't make me laugh.

>>7996416
It goes on: >>7994931

Whoever wrote >>7994783 and >>7994788 has some basic familiarity with the issues, but guessed and got a lot wrong, too.

Another thing he got wrong was:
>you can't really over-design a rocket. It can be over-designed for a given payload need, but the added structure and material adds more risks to the flight, not less.
>Redundancy and safety adds weight which requires more propellant which makes it less safe, and so forth. The rocket equation is one of diminishing returns with mass ratio. Adding 1 kg of dry mass can require 10 kg of fuel,
This sounds plausible, to someone who has read a little about it and is just guessing, but it's pretty stupid when you get into the details.

Even this just line:
>Adding 1 kg of dry mass can require 10 kg of fuel,
When you think of a container, does a 1 kg empty container seem light for 10 kg of dense liquid contents? That's fucking rugged! It's also exaggerated. These are the kind of mass ratios you see in an SSTO. A typical two-stage rocket is usually about a 6 km/s low-thrust vacuum stage on a 4 km/s high-thrust atmospheric stage, with about 1:7 and 1:3 mass ratios, not 1:10. If that sounds like too much, you can go three-stage, or four-stage.

Real-world rocket stages typically carry a larger load than their empty mass, so as you scale them up without increasing the load they carry, they can get much more rugged. They operate on thin margins for reasons of economy, not physics.

>>7994788
This would be a golden post 5 years ago but drop all of your comparisons and deductions and just look at reality today.
>First stage landed safely
>Test fired again and worked fine
>Half a million dollars to inspect it compared to another ~40 million to build a new one.
How memeishly impossible is it to put another second stage and payload on top of your landed, tested booster and launch it again, saving at least half of the cost? You made a good point that it is harder than flight but hard =/= impossible based on what we are seeing right now and the cost benefits are enormous if you can do it.

>>7996530
Also, the cheaper and faster it is, the more customers they'll get.

>>7996530
>Half a million dollars to inspect it compared to another ~40 million to build a new one.
I think it's actually more like $20 million (it was $18.5 million IIRC). In terms of near-term practicality (aside from the gains of experience to be applied to their next generation vehicle), the bigger deal to SpaceX is increasing their launch rate and getting to the point where they have an inventory of proven stages ready to go on short notice rather than a launch backlog. They have to pay all of their salaries and overhead whether they launch 3 times a year or 30 times a year.

Right now, I think their launch rate is bottlenecked by pad operations, not stage production. So they won't enjoy an immediate benefit of increased launch rate. It does give them a larger benefit for when they do streamline their launch operation.

This is why there's some tension over the pricing of launches on reused stages. Their first customer for reused-stage launch asked for it to go up for half the price. But this is more than the direct savings of reusing a stage. They settled on a discount of 1/3rd, which is SpaceX basically passing along their whole savings of not having to build a new stage to the customer.

They've set an eventual goal of around $15 million for a Falcon 9 satellite launch. Satellites need quite a bit of babying, so it wouldn't surprise me if they can eventually do a reusable Dragon V2 launch, or repetitive trucking of simple payloads (for instance, dumb supply modules to be picked up by a space tug), for cheaper.

>>7996637
>Right now, I think their launch rate is bottlenecked by pad operations, not stage production

That might change when or if they get permission to do launch and recovery over land, with them making their own launchpad and all if i recall correctly

I'm a fan of SpaceX and all but the Mars thing has incredible challenges. At the top of my head how do they plan to decelerate a rocket entering Mars when the Curiosity rover was the absolute limit of NASA's tech?

I really hope the accomplish it. I remember when they released the first reusable concept video and I thought it was impossible but they actually did it.

>>7996843
>how do they plan to decelerate a rocket entering Mars when the Curiosity rover was the absolute limit of NASA's tech?
Dude, the space shuttle was the absolute limit of NASA's tech, too. NASA's not all that good at space things, they're a big inefficient bureaucracy, there just aren't a lot of guys trying, for us to compare to.

The Curiosity rover lander was a design to maximize the success probability of a one-time landing. This was a robotic probe, so they worry about things like failing to deploy a ramp. That's what the skycrane was about: land the rover directly on its wheels, rather than try and figure out how to roll the rover off of a lander.

Atmospheric entry at Mars is very similar to atmospheric entry at Earth: the hypersonic part you need a heat shield for is done in the thin air of the upper atmosphere. The main difference is that Earth's atmosphere will slow you right down well into subsonic speeds, even without a parachute, and a parachute can slow you right down to a safe landing speed, whereas the atmosphere at the Mars surface is like the upper stratosphere on Earth, so you need to do a rocket landing, or some fancy combination of parachute, rocket, and shock absorption.

If you master atmospheric entry and propulsive soft landing on Earth, doing the same on Mars is no great challenge. The gravity's lower, and the wind's practically a non-issue. This barge landing SpaceX pulled off is way harder than a landing on Mars would be. They had high wind, they were landing on a rocking boat, and they had full Earth gravity to contend with.

>>7996843
Muskfags will say that NASA are retarded and SpaceX has alien technology that can magically do anything perfectly just like here >>7996940
SpaceX has never landed a rocket from orbit you mongoloid.

>>7997036
>SpaceX has never landed a rocket from orbit
Jesus you guys. I suppose you're going to carry on thinking this is a really important point right up until they do it. Then it'll be, "SpaceX has never landed a rocket on Mars. Clearly they're never going to be able to do that." Then, "SpaceX has never landed a manned rocket on Mars, which is totally different." and so on.

Targetted propulsive soft landing from orbit is something they're doing with Dragon V2. It should be demonstrated within a year or two. Then they're going to do it for the reusable upper stage on their next-generation launch vehicle. Then they're going to use it on Mars.

Anyway, as I already pointed out, it's easier than what they just pulled off by landing a full-size booster on the drone ship rolling in the waves in windy conditions.

>>7995274
Stop oppressing me, shitlord

>>7997078
I mean, they didn't develop flyback boosters before a reusable upper stage because it's easier. A flyback booster is harder. Much harder.

But a reusable upper stage is meaningless for economy without a *highly* reusable booster, and imposes a major performance penalty, whereas even a somewhat-reusable booster can provide significant cost savings at a lower performance penalty.

A propulsive-landing, reusable crew capsule, on the other hand, makes sense with or without a reusable booster because it's necessary to recover it anyway, so the passengers don't die. Recovering it efficiently, conveniently, and in like-new condition are all well-aligned with the goal of not having the passengers die. Additionally, a good capsule is much more expensive than a cheap, non-H2 upper stage with an extended-nozzle booster engine.

This is all about the next generation rocket. With their experience from Falcon 9, they'll expect to make a flyback booster and have it work every time, and with their experience from Dragon V2, they'll expect to have a good chance of landing the upper stage for reuse on the first try.

>>7994132
>I know what Muskfags actually believe
No, you do not.
Lrn2smell-the-Musk

Can anyone tell me why Sea Dragon rocket wasn't ever implemented or copied as a design?

https://en.wikipedia.org/wiki/Sea_Dragon_(rocket)
The Sea Dragon was a 1962 design study for a two-stage sea-launched orbital rocket. The project was led by Robert Truax while working at Aerojet, one of a number of designs he created that were to be launched by floating the rocket in the ocean. Although there was some interest at both NASA and Todd Shipyards, nothing ever came of the design as NASA's Future Projects Branch was shut down in the mid‑1960s. At 150 m long and 23 m in diameter, Sea Dragon would have been the largest rocket ever build

The rocket would have been able to carry a payload of up to 550 metric tons into low Earth orbit. Payload costs were estimated to be between $59 to $600 per kg.

>>7997487
>Can anyone tell me why Sea Dragon rocket wasn't ever implemented or copied as a design?

>why Sea Dragon rocket wasn't ever implemented
>nothing ever came of the design as NASA's Future Projects Branch was shut down in the mid‑1960s

>or copied
>The rocket would then be towed to a launch site, where the LOX and LH2 would be generated on-site using electrolysis; Truax suggested using a nuclear-powered aircraft carrier as a power supply during this phase.

If your basic operating model involves having a supercarrier at your beck and call, the number of entities that could theoretically use your idea is 1, and the number of entities that might plausibly use your idea is 0.

>>7994262
>What he is claiming is like if Apple randomly decided to say they were going to build a navy to match the USN
The goyim know!

>>7997528
>>7994262
>What he is claiming is like if Apple randomly decided to say they were going to build a navy to match the USN
Wow, that is a crazy analogy.

A company that builds big rockets building a somewhat bigger rocket is like a computer company building a Navy?

>>7997487
>costs between $59 to $600 per kg
dat order-of-magnitude range

>>7997558
And things change. If someone told you that Apple would be designing its own CPUs in the 80s or 90s you'd be laughed at, yet here we are now with Apple-designed CPUs being some of the most performant of their type.

I'd also say that old space never had to become a well-oiled machine BECAUSE they had so much cash thrown at them. They never had to become more cost-effective or make their products more cost-effective and so they didn't, leading to wildly huge (and unnecessary) costs all the way down the line.

SpaceX doesn't have that privilege. They have to try the position themselves so that if the government stops using them, they can still exist and even thrive. Given this, it's really not so unreasonable to believe that they can find ways to tighten up the loose and ludicrously expensive ways of old space. It's not surprising at all that they might be able to surpass old space.

>>7995274
You are absolutely disgusting to immediately pull out claims of nazism and one sided /pol/ viewpoints from someone else's hatred of conflagrating, dubious at best memes.

Musk and SpaceX need several nuclear powered transit vehicles with rotating sections, for Mars transit.

On Mars you have small automated shuttle rockets. That will go from the surface to orbit and back all as a single stage. Refueling on the surface and capable of dozens of orbital launches and landings, before major rebuilding.

The transit ships will never stop moving. They will enter earth and mars orbit. Dock with a shuttle, transfer people and cargo. Then the shuttle goes back to the surface. The transit ships then keep on going to the next planet.

>>7997591
Interesting thing: the space shuttle was supposed to have a cost of $118 per kg (in 1972 dollars). Very comparable to the Sea Dragon estimates.

>>7997671
That's called a "cycler". Pretty sure SpaceX isn't doing that, or using nuclear-anything.

>>7997671
Are you aware that launch Earth to Mars launch windows only open every two years or so? You can't send ships back and forth.

>>7997695
There's actually a variety of options for orbits that take you past Earth and Mars regularly, notably the Aldrin Cycler which has an Earth-Mars transit time of about 5 months that recurs as often as regular Mars launch windows:
https://en.wikipedia.org/wiki/Mars_cycler

The main reason a cycler is good is that you can build lots of shielding and sophisticated closed-loop life support stuff, and you only have to launch it all once.

Obviously, it doesn't reduce the delta-V requirements on the stuff you want to transport from Earth to Mars: that stuff has to catch up with the cycler. But stuff to make the time spent in space safe and comfortable can be kept in the cycler.

>>7997695
yeah, if you are going about it with chemical rockets like Apollo.

nuclear ship going several times faster, would eliminate the window problem.

>>7997718
OH SO MUSK IS BUILDING A NUCLEAR ROCKET NOW?
everytime muskfags get called out on their fantasies they come up with even more outlandish technology and financing schemes. The US government would let a private company fire a nuclear powered rocket over their dead body

>>7997738
should be no problem. as long as they don't fire the nuke in atmosphere..

>>7997738
I doubt the thing that's getting announced within the next year or two is a nuclear ship, but it does sound like he wants to eventually build something similar to what >>7997671 describes. This makes perfect sense given that his long term goal is an actual colony, not just a piddly "YAY LOOK WE DID IT" 5-person research outpost.

Whether or not he can actually pull that off is another matter.

>>7997755
No, a cycler or nuclear rocket doesn't really fit with what Musk has said so far.

What does make sense is a really large propulsive-landing upper stage / spacecraft that can carry 100 passengers or 100 tons of cargo from the Earth surface to the Mars surface and be refuelled on the Mars surface to return to Earth. That's pretty much exactly what they've described.

They've also said that they'll need about 5-10 times as many cargo trips to Mars as passenger trips.

>>7996530
>>First stage landed safely
Never been done before, but not particularly impressive to do with respect to other recent space accomplishments
>>Test fired again and worked fine
As the guy said, if you cross the line between perfectly fine and almost perfectly fine, your rocket blows up.

>>7996480
>moving the goalposts.

Why is NASA so focused on liquid hydrogen/oxygen powered rockets when its not the cost effective approach?

>>7997849
>NASA
>Cost effective approach

>>7997823
>>First stage landed safely
>Never been done before, but not particularly impressive to do with respect to other recent space accomplishments
If you don't understand a subject, you should maybe just listen and ask questions rather than seeing if you can bluff your way through.

This (the December flyback landing) is pretty much the most significant "first" since Sputnik. Bigger than the first manned launch, bigger than a man on the moon.

This is a demonstration of the technology needed for airliner-like reusability, which will, over the next decade or two, bring orbital launch down from the realm of major infrastructure and grand national gestures into the everyday world, reducing costs by a factor a thousand and making it possible for large numbers of people to live and work in space.

>>moving the goalposts.
Oh, you're one of these guys, who gets caught saying stupid shit and then posts vague handwavy shit and tries to play it off like, "Anyone smart understands and agrees with me immediately, and doesn't need any explanation." One of those really fucking stupid guys.

>>7997849
Because if you use the water on mars you can use electrolysis to make hydrogen and oxygen, literally making fuel on another planet

>>7997856
>"We're the biggest thing in space travel since Sputnik"
At this rate you could get to Mars powered by ego

>>7997856
>Bigger than the first manned launch, bigger than a man on the moon
oh wow it gets worse

>>7997849
Because they're not hard pressed to find an alternative

>>7997849
>>7997872
It's not a significantly harder process to make methane, or various other hydrocarbons or alcohols that would be easier to handle on an alien planet without much infrastructure.

Even on the moon, there's quite a bit of carbon mixed in with the water they find.

NASA likes hydrogen/oxygen because of its high specific impulse, and because it's hard and they like showing off that they have the fanciest technology (which is what NASA was founded for in the first place: showing off that America has the best technology).

I don't think it's simply true that lox/h2 is not the most cost effective approach. There are various trade-offs, and cost-effectiveness is not a simple, static thing. I think that SpaceX's particular goals, means, schedule pressures, and engineers are such that hydrogen doesn't make sense for them right now. Blue Origin went for hydrogen first, developing their upper stage technology before their booster technology, and I don't think that was a mistake on their part. They're just on a different path.

>>7997881
While some kinds of payloads have been of practical significance despite the extraordinary expense of orbital launch, human beings have only been sent into space symbolically.

History will look back and remember the first half century of manned spaceflight as irrelevant, since launch was so inefficient that only a handful of people could be sent up, and there were no tasks for them to do that they were necessary for.

I like big rockets and things that go into space.

>>7997902
>NASA likes hydrogen/oxygen because of its high specific impulse, and because it's hard and they like showing off that they have the fanciest technology (which is what NASA was founded for in the first place: showing off that America has the best technology).

LH2 is also disliked because it is deeply cryogenic (and materials do funny things at those temperatures), has very low fuel density, seeps out of the walls of its containers, and requires specialized alloys to avoid hydrogen embrittlement. High specific impulse isn't worth those tradeoffs until you're mostly done fighting gravity losses in the early parts of the flight.

>>7997907
>History will look back and remember the first half century of manned spaceflight as irrelevant
It's like flight. What do you think of as the first human flight?

You think of the Wright Bros in 1903, right? Because heavier-than-air craft have been so important and lighter-than-air craft have been so trivial.

You don't think of Bartolomeu de Gusmão in 1709 elevating himself 4 meters with a tethered hot air balloon, or the Montgolfier brothers vs. Jacques Charles and Nicolas-Louis Robert in 1783 demonstrating untethered human flight with hot air and hydrogen respectively.

There was a whole century, arguably two, of human flight before the Wright Bros, but it's, "Oh yeah, that stuff with balloons... I *suppose* they count." right? It never amounted to much. It was mostly demonstrations and recreation.

I think manned spaceflight on expendable rockets (or the pseudoreusable shuttle that cost more than expendable rockets) will be remembered the same way: quaint, silly, and unimportant.

>>7997924
They were doing plenty of flight in WW1

>>7997927
Exactly. Just a decade after the Wright Bros first demonstrated controlled, powered flight, it was an important technology having major effects on world affairs.

In late 2015, we saw two demonstrations of large VTVL rockets flying from the surface to space and back again: one on an actual orbital flight, and a smaller one which lacked an orbital stage and instead tested a passenger capsule, both as parts of development programs aiming for full reusability of orbital rockets.

I think this is going to be remembered as the Wright Bros moment for space travel, although people are going to argue about whether Blue Origin or SpaceX had the "first" that really counts, like some people argue about whether Santos-Dumont or Whitehead was the real "first' rather than the Wright Bros. (I imagine SpaceX will get the credit and Blue Origin will be the footnote)

>>7997927
Which would be after the Wright brothers.

>>7997983
Hence why he's refering to the centuries of flight before the Wright bros....

>>7997823
>As the guy said, if you cross the line between perfectly fine and almost perfectly fine, your rocket blows up.

True, that is why it is difficult, if you get a 99.9% on the space exam, you fail.

This does not mean it's impossible.

By fine, I meant fine, not almost fine, not probably could of done it because most of it seemed to work, I meant fine, checked and good to go. Even if there was something wrong that needed to be refurbished which is definitely possible, that cheap refurbishment (HOLY FUCK FALCON 9 AND THE SPACE SHITTLE ARE NOT THE SAME THING) would still make it more than worth it to reuse which brings us back to the original point I disagree with ''reusability is a meme''.

Great points all around on why its super hard and why people probably shouldn't have tried in the first place because man that airplane comparison was spot on and wow he sure is right, it is difficult.

It is not a meme though, SpaceX has already trumped 90% of those difficulties and is on the verge of reusability with the last challenge (which I can't wait to be overcome because then we can all stop arguing over whether its possible or not) being just reusing a booster after checking that everything is good to go. (Good to go, not almost perfectly fine). Once you have quick, working reusabillity, the price will drop even more so which will open up more customers which will allow them to drop their price a little bit lower. In the future when we have true reusabillity like airliners, that will change the game in space flight.

Just to focus on your point and boil it down though.

>if you cross the line between perfectly fine and almost perfectly fine, your rocket blows up.

Absolutely true but I ask that you take into consideration that although it is difficult, reality is showing us that it is coming and things are looking good.

Final point / tl;dr

It is difficult but not impossible, things are looking bright based on reality and resuabillity is definitely not a meme.

>>7996236
https://www.youtube.com/watch?v=lSx4DGBstYA

>>7999163
SpaceX wants to re-launch this rocket, possibly as early as June.

>>7997959
>cost savings on an existing technology

This has the significance of retractable landing gear, if it actually does prove to be economical. This is not a Kitty Hawk moment.

>>7997959
>although people are going to argue about whether Blue Origin or SpaceX had the "first" that really counts

HAI GUISE

>>7994165
I've never once been to reddit and don't call me a fag. I can't even imagine how shitty that place must be if the tards that come from it act the way they do on 4chan. It sounds like another 7chan, desu.

>>7994299
pshaw. You call THAT a big rocket?!

>>7999896
That never went that high, in terms of VTVL there were Apollo test vehicles that also managed it. No one was claiming the shitty test rockets were groundbreaking, only the recovery of stages used in actual orbit-capable flights.

Friendly reminder that SpaceX makes 'old spacers' realize they have had their time in the sun and will soon turn into ash like the good little vampires they are.

>>8000077
Hope they've been saving some money for their impending unemployment

>>7994149
>the aerospace industry declared that impossible in the 90s so it can never be done.

>>>/his/

>>7999561
>SpaceX wants to re-launch this rocket, possibly as early as June.

After test firing it ten times first. If it passes those test firings it will be doubly impressive.

>>7999841
>>cost savings on an existing technology
>This has the significance of retractable landing gear, if it actually does prove to be economical. This is not a Kitty Hawk moment.
The Wright Bros? Pfft... they just put together gliders that already existed and internal combustion engines that already existed with some trivial steering technology. Not an important moment.

Retractable landing gear didn't make flight a thousand times cheaper. Propulsive landing of orbital rocket stages will make orbital launch a thousand times cheaper, bringing it into the realm of the everyday. The booster's the more valuable and technically challenging stage to recover. That the upper stage will follow is just a matter of time.

>>8000057
A fundamental problem with Delta Clipper is that they still weren't working on a practical method.

The idea was that they'd start with this atmospheric rocket, nowhere near orbital capabilities, and evolve it into a reusable SSTO.

There was no plan for staging. It was going to be SSTO or nothing.

SSTOs are risky, reusable SSTOs much more so. There has never been a working SSTO vehicle, although many SSTOs have been proposed. The trouble is that every additional ounce of structure cuts into the payload, and if the payload to LEO goes negative, you just don't go to orbit. So you have to set hard limits on structural and recovery mass (and tight ones, in the case of orbital launch) at the napkin sketch stage of design and stay within them all the way to the working product. That makes all the engineering difficult.

Staging gives huge benefits, due to the rocket equation being exponential with respect to total delta-V. Dropping mass in the first few km/s means that it's barely relevant to ultimate orbital performance. Dropping *most* of the dry mass early in the flight makes it almost easy.

Two-stage is actually cutting it a bit close. You're carrying everything you need for lift-off all the way to space. Three-stage designs are quite standard, with the bottom two stages typically using parallel stages: Soyuz is 3-stage, an Atlas V or Delta IV rocket with strap-on boosters is 3-stage, Ariane 4 and 5 are 3-stage (Ariane 4 was 4-stage with strap-on boosters), Saturn V was 3-stage, Falcon Heavy and SLS will be 3-stage.

>>8000506
The VentureStar could be built with today's technology, they just had tank materials problems in the late 90s that we've actually solved.

>>8000526
>The VentureStar could be built with today's technology, they just had tank materials problems in the late 90s that we've actually solved.
The X-33 could be built with today's technology, you mean. The tank materials were the reason they couldn't build the subscale, *suborbital* technology demonstrator.

The tank wasn't the only problem with VentureStar. I mean, look at the size of this fucking thing. It was only ever estimated to reduce launch costs over the actual space shuttle by a factor of ten, IF everything went according to plan. That's equivalent to the expendable version of Falcon Heavy.

The claims about payload and cost were napkin-sketch level. The engineers working on the design kept lowering the payload as they got closer to a buildable system. When NASA caught on that their payload was evaporating, they made a fixed payload requirement part of the development contract. Then the size of the vehicle started creeping up.

It was a marginal concept. They couldn't design it conservatively. Even if it worked, it would probably have cost a lot to operate, or they would have suffered frequent vehicle losses, because they couldn't tolerate small irregularities or the extra mass required to make replacement parts easy to swap out.

>>7995717
Are you on a government watchlist?
You should look into getting on a government watchlist.
Just like, download some CP and delete it off your drive. Just for the sake of it.

>>8000402
>trivial steering technology
>wing warping
Lrn2aviation fgt pls

>>7994974
Being cheap isn't a reason to reuse. It is, in fact, a reason NOT to reuse.

Unless you mean that the rocket is still expensive as fuck, but the fuel is a lot cheaper.

>>7994132
According to my very, very rough, very amateur calculations, a rocket with the efficiency of the raptor engine would need a mass ratio of about 30 in order to get into orbit then land back on earth.

This is erring on more than enough fuel, as long as reentry and landing is very fuel efficient, making use of drag as much as possible.

>>8000924
Do you understand that this is a two-stage vehicle?

>>7995717
When the second N1 exploded, the blast had a force of 7 kilotons.
https://en.wikipedia.org/wiki/Largest_artificial_non-nuclear_explosions#Rank_order_of_largest_conventional_explosions.2Fdetonations_by_magnitude

This looks like it could be 2-3 times the size.
Do they plan to launch this thing from the Nevada test site?

>>8000957
>Do they plan to launch this thing from the Nevada test site?
They went that far out in the middle of nowhere to test nukes because of the fallout. The remoteness of conventional launch facilities is sufficient for exploding rockets, even very large ones.