Elon Musk Announces That Raptor Engine Test Has Set New World Record (space.com) 144
A reader shares a report from Space.com: A test fire of SpaceX's newest engine reached the power level necessary for the company's next round of rocket designs, CEO Elon Musk said on Twitter. "Raptor just achieved power level needed for Starship & Super Heavy," he tweeted on Feb. 7, four days after he shared a photograph of the first test of a flight-ready engine. [Musk added: "Raptor reached 268.9 bar today, exceeding prior record by the awesome Russian RD-180. Great work by @SpaceX engine/test team!"
The Raptor engine is designed to power the spaceship currently known as Starship as part of the rocket assembly currently known as Super Heavy (previously dubbed the BFR). The first Raptor test fire took place in September 2016, when the company was targeting an uncrewed Mars launch in 2018. Three Raptor engines like this one are built in to the Starship Hopper, which has been under construction in Texas and which SpaceX will use to begin testing the rocket technology in real life. Eventually, SpaceX plans to assemble 31 Raptor engines into the Super Heavy rockets, with another seven Raptors on the Starship itself.
The Raptor engine is designed to power the spaceship currently known as Starship as part of the rocket assembly currently known as Super Heavy (previously dubbed the BFR). The first Raptor test fire took place in September 2016, when the company was targeting an uncrewed Mars launch in 2018. Three Raptor engines like this one are built in to the Starship Hopper, which has been under construction in Texas and which SpaceX will use to begin testing the rocket technology in real life. Eventually, SpaceX plans to assemble 31 Raptor engines into the Super Heavy rockets, with another seven Raptors on the Starship itself.
Signed up to go to Mars ? (Score:3, Interesting)
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Re: Signed up to go to Mars ? (Score:3, Funny)
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I just wish they'd hurry up and start recruiting space miners to go to the asteroid belt.
A few million miles, a robot sidekick, and a cargo hold full of gold, what more do you need?
Re:Signed up to go to Mars ? (Score:5, Interesting)
I just wish they'd hurry up and start recruiting space miners to go to the asteroid belt.
You read too much sci-fi. IRL, when miners go to the asteroid belt, they will be robots, not humans.
There is no practical reason to send humans beyond earth orbit. Robots don't need life support, they don't need expensive ultra-reliable gear, and they don't need to come back home.
https://xkcd.com/695/ [xkcd.com]
Re: no practical reason... (Score:2)
Re: Signed up to go to Mars ? (Score:3)
There is no practical reason to send humans beyond earth orbit. Robots don't need life support, they don't need expensive ultra-reliable gear, and they don't need to come back home.
Yep, it's great that we already have that AGI to control with low latency our newly invented unbreakable space mining equipment. Otherwise we'd have to send people along to control and fix things.
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Yep, it's great that we already have that AGI to control with low latency our newly invented unbreakable space mining equipment. Otherwise we'd have to send people along to control and fix things.
We're a lot closer to having AGI than having people on asteroids.
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Re: Signed up to go to Mars ? (Score:2)
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An army of robots will do most of the mining and smelting work, but there will be no substitute for onsite humans in command and control, dealing with who-knows-what unknowns. The latency at this distance is too high for teleoperation, and the real-time decisionmaking that goes with directing a robot army is not something our AI will be capable of doing until it achieves real consciousness. Having humans go there along with the robots is slightly less "impossible" than conscious AI.
Re: Signed up to go to Mars ? (Score:2)
> There is no practical reason to send humans beyond earth orbit. Robots don't need life support, they don't need expensive ultra-reliable gear, and they don't need to come back home.
Only until they unionise
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... and most importantly they're not aware where they are, for what reason and what to make of it, in general they do not care about exploration, progress and dreams - they're tools.
My point is that "we do this and the other things not because they're easy, but because they're hard".
There is no practical reason to send humans beyond earth orbit ...
Why to send humans anywhere then, what's the practicality of sending to orbit, why to cross an ocean or a mountain, why to do anything besides one's basic needs like e.g. reading a novel?
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"There is no practical reason to send humans beyond earth orbit."
Wanna know how I know you don't work with automated robotic systems here on Earth?
Hint: I design embedded systems robots for semiconductor manufacturing.
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Humans are dirt cheap compared to space robots, never mind artificially intelligent space robots we can't build yet, provided you get their life support resources in space. Those resources will be the primary products of asteroid mining.
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There is no practical reason to send humans beyond earth orbit
There's no practical reason to go to the grocery store ether, a robot could take all day to pull out products you wanted.
Or maybe, just maybe, onsite human judgement and intuition has practical value.
Re: Signed up to go to Mars ? (Score:2)
It could be a hit, all they have to do is fake some bearing failures and have the robots rub their brows and say "Gosh, I don't know if we can fix this...", just like the human mining reality shows on Earth.
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What more do you need?
High-grade sexbots.
Re: Signed up to go to Mars ? (Score:4, Insightful)
The asteroid belt consists mainly of the same stuff than the Earth Moon and the Earth's crust anyway, and the later have more of it.
Just a simple comparison of 16 Psyche with our recoverable mineral reserves betrays your deception. Just because Earth has considerable amounts of iron, nickel and siderophiles in its core doesn't mean that they're easily accessible - they're in the fucking core! You're *never* getting to the core.
The energy required to move something from the Asteroid Belt to the Earth is so high that the cost will by far outnumber the possible revenue for selling the stuff. Even if you mine an asteroid consisting of pure gold or platinum, you will pay more for the fuel to get there and back than you can possible sell the gold and platinum for on Earth.
I would love to buy me some platinum from where you're buying it. Apparently it must be super cheap compared to the price of some methane and oxygen. I would, however, not wish to buy any of your math or physics textbooks, apparently they're awful.
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Apparently it must be super cheap compared to the price of some methane and oxygen.
I don't know. What's a reasonable price for methane and oxygen on an asteroid ?
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Something less than the cost of synthesizing it yourself from local resources, I'd imagine. CHON are the most common elements in the universe after all - and while hydrogen has a pesky tendency to escape from low-mass bodies, enough gets bound into water, hydroxides, and various other compounds to be useful for a long time to come.
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Why would you need to have methane? Hydrogen will do just fine for propulsion. And it can be create from in situ water, which is being found practically everywhere.
The nice thing about the roids is that the minerals aren't buried.
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6 percent of the Earth's crust is iron (and another 0.3 percent is Nickel). That means that just in the Earth's crust, there is 500*10^15 tons of iron (and another 25*10^15 tons of Nickel). The whole mass of 16 Psyche is just 27*10^15 tons.
We have twenty times more iron and nickel within the first 20 km of the Earth's crust than the whole of 16 Psyche.
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We have twenty times more iron and nickel within the first 20 km of the Earth's crust than the whole of 16 Psyche.
Plus we have tons of scrap metal.
Re: Signed up to go to Mars ? (Score:4, Interesting)
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We don't need that much iron and nickel that would require us to fuck up the whole crust or the atmosphere. Also, if you're going to invoke magical mining technology that you can get on 16 Psyche, we get to invoke magical mining technology that can cleanly extract metals from seawater, or a from a piece of useless desert.
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You mean the magical technology of picking up chunks of almost pure metal from the ground?
How much do you estimate we'd have to spend on rocket technology before we can ship, say, a billion tons of iron from 16 Psyche to Earth surface ?
How much do you think you could sell that iron for ?
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Why would you sell raw iron on Earth, surely they would buy that at the orbital space port?
This is exactly the other side of the insistence that equipment has to be expensive, because it has to be produced on the Earth's surface.
What is the list of assumptions, and which of them are reasonably still true if you're also engaging in large scale mining in the asteroid belt?
There are lots of minerals more expensive than iron that might get returned to the surface, but you'd probably be using the iron to support
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Also, the iron will most likely be more useful in space anyway.
This. People are overlooking facts like there are many asteroidal materials we don't need to ship to Earth but would be immensely valuable in space-based construction. Precious metals and the like might be useful to transport to earth but things like iron, aluminium, silicon, etc. would make space-based construction feasible. The cost of lifting all that crap out of a gravity well like Earth is what keeps us Earth-bound.
I'm not discounting the vast cost of setting up orbital refineries and construction ya
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We're just going to sail out there, then tack back towards the sun with our solar sail. Not fast, but the iron isn't going to go bad. You're making this way more complicated than it needs to be. /s
Inter-orbital logistics (Score:3)
I think you underestimated rather severely: Escape velocity is sqrt(2) * orbital speed, so you're right that it's about 4.3km/s from geostationary orbit - but that only gets you away from Earth - you'd still be in basically the same orbit as Earth around the sun, and need even more delta-V to reach the asteroid belt.
I *think* that would be equivalent to the difference in solar escape velocities from each, so Earth's orbit (30km/s * sqrt(2)) - asteroid belt orbit (25km/s *sqrt(2)) =~ 7km/s. If somebody know
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Why land on the space elevator at all, why not land on the surface and not use propellant for that at all?
It seems a lot more reasonable if you presume that you'd want to mine minerals that are expensive, rather than trying to mine minerals that are cheap.
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There is nothing complicated about it,
Space nutter phrase #23 detected.
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Delta rockets run on hydrogen and oxygen. Atlas uses kerosene and oxygen. Falcon uses kerosene and oxygen. Blue Origin's smaller engine uses hydrogen and oxygen, and the big one under development uses methane and oxygen. SpaceX's new engine under development uses methane and oxygen. Soyuz uses oxygen and kerosene. Long March (other than 2) uses oxygen and kerosene.
Methane is somewhere in the neighborhood of $0.0025 per kg. NASA's numbers from 2001 say hydrogen was $3.66 per kg and oxygen was $0.16 per kg. K
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Solar sails work just fine in orbit too - so long as they're in microgravity and don't have to support their weight or fight atmospheric drag they're good to go.
Of course, in planetary orbit you have to constantly change orientation to maintain orbital acceleration, which puts much greater demands on your attitude control system (gyroscopic, I would assume), and greatly reduces your average acceleration, since you can only accelerate for half of each orbit while moving away from the sun, and can only briefl
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>Iron is too reactive to occur in its native state,
Not for long (geologically speaking) - but it takes a long time for corrosion to reach the inside of a sizable lump of non-porous iron. Google states that the oldest iron artifacts date from 2000BC, so they've survived 4000 years without completely rusting away, and a meteor has a much lower surface-to-volume ratio (and thus rusting speed) than a knife.
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That's why everybody goes to the Belt. Where else can you get an easy claim a piece of rock?
On Earth you need a time machine or a billion dollars. On the moon you need an international treaty. On Mars you need a ride home, and bad.
In the Belt the paperwork is easy, and home is mostly downhill.
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I would love to buy me some platinum from where you're buying it. Apparently it must be super cheap compared to the price of some methane and oxygen.
While platinum is way more expensive than some methane and oxygen I wonder how it compares to the cost of a spaceship and all the other bits you need to to go to an asteroid, find one with platinum, mine it, refine it and get it back to earth in a reasonable time frame. That probably bumps the cost at least a little bit.
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OK, but one ship to get you out there, and different ships that stay out there that you fly around to find and capture the asteroid, the refinery just floats around, and the return ship for the minerals doesn't need life support or high speed. And you only return some percent, the rest is used to grow the operation.
Re: Signed up to go to Mars ? (Score:2)
Let's say you can miniaturize everything needed to mine an asteroid into a one-ton spacecraft
That's most likely not how it would work. You'd first need to assemble large pressure vessels on site, to deal with carbonyl separation. But once you have them, *limiting* the output would *not* be the way to amortize the investment.
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Also, you're assuming that the mined materials will be returned to Earth. It seems quite probably to me that if
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I recall reading similar cost arguments about why we couldn't get at lots of the oil that is currently being fracked out of the ground just fine.
With that argument you could also say that we won't have any trouble extracting enough metals from the ground.
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I hear there's a bunch of excess carbon in the atmosphere.
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Spend enough energy and you can turn it into whatever you want though. The Mars-colonizing plans commonly expect to convert CO2 and water into methane and O2 using... a process whose name I can't remember.
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What physics reasons are these? I suspect you are getting confused with the fact that iron-56 is the most stable element going, However out the the ten most abundant elements in the Milky Way galaxy, carbon is number four and iron only number six. Even in the solar system carbon is significantly more abundant than iron.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Now when we have reached the heat death of the universe it will all be iron-56, but that is many trillions of years away.
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>Now when we have reached the heat death of the universe it will all be iron-56, but that is many trillions of years away.
That seems unlikely, as it would require all other lighter materials to have fallen into stars and been fused into Fe56 or heavier - a process that would probably completely choke off the fusion reactions long before everything was converted.
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Except if everything is not converted to iron-56 there is more heat to be extracted from the universe and by definition the heat death has not been reached.
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There's only more heat to be extracted if there exists some method to extract it - and at 1 atom per cubic light year fusion is not possible.
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It seems unlikely that Earth-based raw materials will ever be more commercially viable in space, even LEO, than asteroid-based ones, once asteroid production has become commonplace. The delta-V from the asteroid belt to LEO is approximately the same as from Earth's surface to LEO, and much more cost-effective propulsion can be used when you're not having to provide gravitational support forces and fight your way through an atmosphere. Especially if we're dealing with terrestrial supply limitations that dr
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Re: Signed up to go to Mars ? (Score:4, Informative)
The $60 per barrel argument is correct, but that's not why fracking shale became popular. In the late 70's/early 80's the price per barrel was over $100 but nobody was fracking. It became popular because of technological advances in horizontal drilling in the late 90s. The shale layer is frequently tight - 5-500 ft thick at depths of 5000-15000 ft (http://www.marcellus.psu.edu/resources-maps-graphics.html) The only way to make the effort of fracking economical is if your well bore can run down, and then along the shale layer for 1000's of feet or miles. That requires horizontal drilling.
It also helps that there's a lot of natural gas in shale, making fracking all that much more economical outside of the price-per-barrel of hydrocarbon. In some areas (eg Marcellus) that's the only reason to frack. In other areas the methane is of minor value compared to the heavier hydrocarbons that come out (like natural gas liquids).
I remember talking to an engineer from a drilling company a few years ago that said with current drilling technology they could drill down, under the Grand Canyon, then back up on the other side and hit a target at the surface only a few feet wide. There are major negative environmental impacts of fracking and the subsequent use of the produced fuel, but the the horizontal drilling capability on its face is an engineering marvel (to me at least).
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To be fair, most of that previously unrecoverable oil is still not economically recoverable, except for the fact that it's necessary to power our current infrastructure. The energy return on investment for a lot of the new oil sources make it uncompetitive with other energy sources. That's why, except for very special circumstances, nobody burns oil or oil products for electricity anymore. We burn it in our cars because we have a massive existing infrastructure set up to do so.
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At current over-supply prices, a lot of fracking wells just might be operating at a loss.
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Gold is selling for $42k/kilogram at the moment. At $1million wholesale per BFR launch, that'd mean ~50kilos of gold is the breakeven point.
What do you think is going to happen to the price of gold when you bring a whole bunch of it back from space? It won't stay at that price, thats for sure. It might be profitable, once.
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World gold production for 2017 was 3150 metric tons. Basically bring back a single ton (aka 1000 kg) or $42 million USD would have a negligible impact on world gold prices. You would need to bring hundreds of tons back to have a significant impact on prices.
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Thing is, you only have to set up the mine once, and then can keep shipping back the valuable ores for a very long time. Add a factory to use the bulk materials like iron that aren't worth shipping back, and you can build more of both, so that your investment in equipment continues to multiply for centuries
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Seems like a waste for gold though. Better to use it as an anti-corrosion coating on sewer pipes - play to one of its few strengths.
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There was once a film about something like this......
That's some shockwave (Score:2)
Short duration test with a massive shockwave at the end.
Makes me wonder how well the engine would handle a full duration burn without blowing up.
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In exactly the same way? The beginning and the end are always going to be the same, just the middle part is longer.
The middle is where all the interesting stuff happens. Just ask the crew of the challenger all about the middle part.
Re: That's some shockwave (Score:2)
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no, it's looking like more chemical rockets
we need order of magnitude improvement in exhaust velocity for serious interplanetary travel
Elon is exaggerting (Score:5, Informative)
The RD-181 has the record for the highest chamber pressure for a flown engine. (And the RD-180 is only a few psi behind, so I'm not going to slam Elon for mixing them up.)
But the Raptor is currently a test-stand engine, and the record for tested engines is over 300 bar.
Testing an engine at a higher pressure than it flies in order to demonstrate a safety margin is of course completely normal. Aerospace uses a lot smaller margins than the factor of 2 used in a lot of civil engineering, but I expect a test at at least 110% of flight pressure.
So while this is an impressive demonstration worthy of praise, it is not any sort of record.
Re: Elon is exaggerting (Score:3)
The lunatical RD-270M and RD-702 were test fired at over 300 bar.
270M is a remarkable beast, getting both monsterous chamber pressure an temperature while being fed chlorine pentafluoride and pentaborane. Only devil knows from what its combustion chamber and turbos are made of.
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while this is an impressive demonstration worthy of praise, it is not any sort of record
I don't really give a crap whether it's a record or not, the point is to lose the current dependence on Russia.
Re: Elon is exaggerting (Score:2)
What's there to correct; he just made all that shit up. There are no official chamber pressure numbers listed for the RD-181, but it is basically an RD-191 modified for use on the Antares. Since the RD-191 has a chamber pressure of 257.8, the RD-181 should be about the same, putting both of them behind the RD-180.
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No publicly available information is not the same thing as no available information.
Remember, he's an industry insider. Russians marketed these engines to US for a while, and that marketing most certainly included spec sheets not available to public.
Re: Elon is exaggerting (Score:2)
Yep, I forgot that all of slashdots ACs are industry insiders.
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All? No. But this is site for the tech nerds. There are quite a few tech industry insiders here that can post information not available publicly as ACs.
Already far in the "diminishing returns" territory (Score:5, Informative)
If I read de Laval nozzle [wikipedia.org] equation correctly an increase in the combustion chamber pressure has minimal impact on the exhaust velocity (going from 260 Bar to 300 Bar has less than 1% improvement).
Combustion chamber temperature is a far better indication of efficiency of the engine and has a far more direct impact of exhaust velocity than pressure.
Credit where credit due - design requires 170 metric tonnes of force, test fire got 172 metric tonnes (design works as expected).
Re: Already far in the "diminishing returns" terri (Score:2)
Re:Already far in the "diminishing returns" territ (Score:5, Informative)
Chamber pressure is correlated to both thrust (higher chamber pressure = higher mass flow rate) and efficiency (and thus ISP, see here [researchgate.net]).
AFAIK, thrust density is the more key factor here, at least for Super Heavy (the first stage). There's a sort of "maximum height" to a rocket stage which relates to the thrust density. Your ability to pack more engines into the rocket corresponds to the rocket's cross section at the base. These engines in turn have to lift a column of liquid sitting above them; each engine can be viewed as having to lift the portion of the column of liquid directly above it (in addition to dead mass and payload). Eventually you get to a height where the mass of liquid (plus overhead) above each engine equals the thrust, and you don't move at all. The higher the thrust density of your engines, the taller you can realistically make that stage, the more fuel it can carry, and - for a given ratio of lower stage mass to upper stage mass - the heavier the payload it can launch (for a given dV). Other options to increase rocket upper stage masses come with disadvantages, such as making the rocket higher diameter (more air resistance) or adding strap-on boosters (more air resistance, more complexity, more work in recovery for reuse).
Thrust density is primarily of importance for lower stages (which is why you don't see many hydrolox lower stages without boosters), and why strap-on boosters (incl. very high thrust density solid rocket boosters) are commonly added to the first stages of large rockets. Thrust density limits are also why small rockets tend to be shaped like pencils (very high aspect ratio) while large rockets tend to be fatter, particularly at the base. For upper stages, ISP is of greater importance.
Also, for a rocket of a given (constant) height, improving its engines' thrust density comes with another advantage: they burn through their fuel faster and deliver the stage's dV faster. While there are limits to how fast you want to do this in the lower atmosphere, once you're past max-Q, more thrust is better (up to the G-force limits of your payload/passengers), as it means lower gravity losses.
Comparison to Saturn V rockets (Score:2)
It would be interesting to see what progress has been made over 50 years, if anyone has some figures.
I suppose that the key one is actually total thrust per kg of fuel. And then kg of engine required to produce a kg of thrust.
My guess is not much, given that by the 1960s the physics has been worked out pretty well and the materials have not changed markedly.
Re:Comparison to Saturn V rockets (Score:5, Informative)
The Saturn V's first-stage engines were crude and inefficient due to problems scaling up the engineering of smaller rocket motors, with bodges added to solve difficulties with the flow of oxidiser and fuel into the engine. The Soviet solution was to use multiple smaller injection systems in separate combustion chambers.
By the late 1960s the Isp figure for LOX/RP fuels was about what we can get today, 300s-plus at sea level for well-designed engines like the RD-170 derivatives (the F1's sea-level Isp was 263s by comparison). The big steps made in rocket engineering are design and materials. The structures are lighter but stronger since the CAD tools allow better understanding of where to add mass and where to remove it without lessening strength, rigidity, resistance to vibration, heat dissipation and other factors. The engines are modelled and tested in simulation a long time before any metal is bent or additively-fabricated, the shapes and structures can be more complex thanks to new manufacturing processes, new alloys and composite materials are available etc. etc.
Re:Comparison to Saturn V rockets (Score:4, Interesting)
I love the various hacks that have been used in rocketry over the years to deal with "difficult problems", which throw away a bit of performance in order to not have to deal with them. One of the most recent ones that springs to mind is that North Korea "dealt with" the stability problems on their missiles by adding a ring of stationary (no axial rotation, aka non-maneuvering) grid fins around the base. They deliberately increase the drag of the first stage in order to keep it stable (like a shuttlecock).
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In the early 2000's NASA published a lot of software allowing for better simulation and design of nozzles and reaction chambers, leading to much better design efficiencies. It was right after that that Musk, Bezos and Branson decided to invest in space programs
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The Soviet solution was to use multiple smaller injection systems in separate combustion chambers.
The German solution. Evidently, they kidnapped better rocket scientists than we did.
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By the time of Apollo the German scientists were behind the times engineering-wise never mind in the propellants race. The US engineers at Rocketdyne couldn't resist the idea of bigger is better and went for a motor design with a unitary combustion chamber and giant expansion bell, then fought for years to solve the gas flow problems that design decision caused. Finally they had to accept lower efficiency to get it to work well enough which more than cancelled out the expected savings in weight and manufact
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My guess is not much, given that by the 1960s the physics has been worked out pretty well and the materials have not changed markedly.
We have much better ways of 3D modelling, much better materials (like single crystal nickel alloys), and also much improved manufacturing techniques. The basic physics were known in the '60, but you couldn't model an entire rocket engine, because of wide scale interactions between pressure, temperature, intermediate reaction products, pressure wave propagation and deformation of the engine.
See: https://www.youtube.com/watch?... [youtube.com]
Also, some things may have been possible in the '60, like machining special allo
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That graph shows a 7% increase in ISP for a 70% increase in ISP. IIRC, there is only so much you can increase the mass flow rate by squeezing harder at this point on the operating curve.
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The challenge is not "squeezing harder". The challenge is "not obliterating your combustion chamber". The higher the pressure, the more reactive the combusting gas/plasma is with the walls of the combustion chamber. It's extremely hard to find materials that these conditions won't eat away.
Seems like a small safety margin (Score:1)
If it's supposed to work at 170 tonnes, testing it under ideal conditions at 172 isn't leaving much room for things to go wrong.
Re: Seems like a small safety margin (Score:2)
Clickbait algorithm seems to be changing. (Score:3)
The it evolved to "always add Elon to the title and a negative slant". Getting an angry response from Elon is the lottery prize. But even without it, decent uptick in clicks.
Then it seems to be evolving to "drop the negative slant, the shorts have moved on. Just mention Elon".
What is it now? Seventh Elon story in three days?
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