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For those who aren't following this religiously like I am, here's the Tl;Dw: SpaceX's falcon 9 is pretty big, but Starship is massively larger. It's also made
by mabbo 6y ago
For those who aren't following this religiously like I am, here's the Tl;Dw:
SpaceX's falcon 9 is pretty big, but Starship is massively larger. It's also made cheaply out of steel in a huge garage in rural Texas. The engines are the most advanced ever made (arguably). Tomorrow, SpaceX is going to try to fly the prototype 12.5km up, then have it freefall, falling sideways. At the last moment, it will reorient itself and land on a landing pad.
Or, it will explode stupendously.
It's going to be awesome either way.
- valuearb 6y agoIt’s a Heinlesque story.
- nine_k 6y agoYes, indeed, we have plenty of real-life cyberpunk around us already, may it please be the time when earlier space SF finally starts to become real, too? :)
- alangibson 6y agoThe world's most sophisticated engines on a vessel that started out as a water tower. I can't get enough of Starship.
- Florin_Andrei 6y ago> The engines are the most advanced ever made (arguably). Maybe not arguably. They embody a technology that's been considered for a long time the Holy Grail of rocket science - the full-flow staged combustion cycle: https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-flow_staged_combustion_cycle https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-f...
- NikolaeVarius 6y agoAs much as I love the Space Shuttle, I wish the US had not went all in on Hydrogen Oxygen. The RS-25 are amazing engines, but we could have had operational full flow staged engines 20 years ago if we had gone down that route. Though probably not the landing part.
- avmich 6y agoInteresting that full flow LOX-LH2 engines could be easier to get, as oxygen and hydrogen can be ignited in a wide range of ratio. With LOX-kero you might have to have a two stage gas generator, when first you ignite components with a good ratio and then add a component to the already established combustion.
- elteto 6y ago> With LOX-kero Small nitpick: kerolox is much nicer sounding and what people know them as ;)
- jsjohnst 6y agoLH2 is way less dense than RP1 though, so you’d need a significantly larger fuel tank to carry the same amount of fuel. Hydrolox (LOX-LH2) is about 30% more power than Kerolox (LOX-RP1), but is about 3.5x less density. Source: https://en.m.wikipedia.org/wiki/Liquid_rocket_propellant#Bipropellants https://en.m.wikipedia.org/wiki/Liquid_rocket_propellant#Bip... Hydrolox - Ve: 3,816 d: 0.29 Kerolox - Ve: 2,941 d: 1.03 If you were wanting to optimize for high specific impulse, it seems LOX-LH2:Be or a fluorine based fuel is the way to go purely on the numbers (not accounting for cost or stability).
- blackrock 6y agoNASA should’ve kept producing the Saturn V. Over time, the production costs should’ve come down. The shuttle was a rather mediocre trade off, in terms of LEO payload capacity. Although granted, the shuttle landings were pretty cool.
- phendrenad2 6y agoThanks! Just started reading about rocket engines, I don't think most people realize how many moving parts the SpaceX engines have!
- FlyMoreRockets 6y agoOkay, I'll bite, How many moving parts do the SpaceX engines have? Assuming the fuel and oxidizer impellers are on a common shaft, that's one. There must be a throttle valve somewhere, so that's two. What am I missing? Are there reduction gears?
- m4rtink 6y agoThey use pintle injectors in the Merlins, so that does move as well (though only a short distance) and is likely what makes them so throttleable. https://en.m.wikipedia.org/wiki/Pintle_injector https://en.m.wikipedia.org/wiki/Pintle_injector
- FlyMoreRockets 6y agoNot sure why I was downvoted. Are the moving pintle injectors separate from a throttle vavle? I have studied a lot of pintle injector designs and it can go either way. Reguardless, a moving pintle injector typically only has two moving parts.
- marcusverus 6y agoTL;DR: Liquid-fuel rockets work by combining a liquid fuel with oxygen. To get the fuel and oxygen into the combustion chamber in huge quantities, they use a big fancy pump. To power this big fancy pump, all liquid-fuel rockets burn fuel in a separate combustion chamber, using the hot gas to power the pump. After the gas powers the pump, it has to go somewhere. Most rockets just dump the gas (these are called 'Gas-generator cycle' engines). This is nice and easy (ha), but it also means that the gas isn't going through the main combustion chamber, so it isn't propelling the rocket. The rockets on Starship re-use the gas that drives the pumps, pushing them into the combustion chamber and burning any unused fuel/oxygen to propel the rocket.
- mschuster91 6y ago> The rockets on Starship re-use the gas that drives the pumps, pushing them into the combustion chamber How is that possible? From a total layman's point of view, the pressure in the combustion chamber should always be greater than whatever the pump can put out, thus leading to a pump stall... what am I missing?
- maccam94 6y agoActually the pump has to be able to put out as much if not more pressure than the pressure generated in the combustion chamber, otherwise it wouldn't be able to push a steady stream of fuel and oxidizer into the chamber. I recommend watching or reading https://everydayastronaut.com/raptor-engine/ https://everydayastronaut.com/raptor-engine/
- lutorm 6y agoAs the other post says, this cannot be true, otherwise how could the engine work. You'd not get any propellant into the combustion chamber.
- mabbo 6y ago> To power this big fancy pump, all liquid-fuel rockets burn fuel in a separate combustion chamber, using the hot gas to power the pump. There's some engineers in New Zealand who might have something to say about that... https://en.m.wikipedia.org/wiki/Electron_(rocket) https://en.m.wikipedia.org/wiki/Electron_(rocket)
- DennisP 6y agoEveryday Astronaut did a nice explanation of the Raptor and various simpler designs, and what's so great about full-flow staged combustion: https://everydayastronaut.com/raptor-engine/ https://everydayastronaut.com/raptor-engine/
- mabbo 6y agoThis is the internet. I say 'arguably' because someone out there wants to argue.
- hinkley 6y agoAnd look! You found a friend!
- beamatronic 6y agoThat is not strictly true.
- bertil 6y ago> It's going to be awesome either way. That might be a better definition of science than “It’s like messing around, but taking notes.” I love how everyone quotes it, and SpaceX deserves the credit for making that attitude popular. But what really makes it possible is cheap cameras — so when watching a blast that is likely destroying every living thing and destroying every piece of electronic in its way, I’ll be cheering for GoPro too.
- NortySpock 6y agoI think the increased telemetry ("3000 channels" per the Falcon 9 AMOS-6 explosion; who knows what Starship will have) and the ease nowadays with which one could store the data on an SD card tucked inside every multiply-redundant avionics box, makes it much more likely you'll be able to pinpoint the cause of an error even after a catastrophic explosion. Hence enabling SpaceX to fail-fast with confidence that they will be able to find the problem from the data and fix it. Plus apparently they're relatively cheap to build, that just makes the test even cheaper. https://arstechnica.com/science/2016/09/spacex-with-a-manifest-of-70-missions-vows-to-safely-return-to-flight/ https://arstechnica.com/science/2016/09/spacex-with-a-manife...
- elteto 6y agoIf you care about telemetry then you can’t store it, you have to beam it back. And SD cards are a nightmare from a reliability standpoint. Nobody (in this context) would do that.
- NortySpock 6y agohttps://www.vice.com/en/article/pga9dk/what-its-like-to-find-a-spacex-rocket-washed-up-on-a-tropical-beach https://www.vice.com/en/article/pga9dk/what-its-like-to-find... They at least used SD cards in GoPro cameras on fairings. I admit I cannot authoritatively speak to what they are using for telemetry storage if they decided to go that way.
- jsjohnst 6y ago
- jacobush 6y agoOr, you will not go to space today.
- jlmorton 6y agoJust to add a bit more color on size: Starship itself is about 50m in height, somewhat shorter than the full Falcon 9 stack (70m). Starship has a much larger diameter though, at 9m vs 3.7m for Falcon9. But Starship is just the second stage. That's what's being tested tomorrow. Eventually this will sit atop a massive new super-heavy booster. The full stack will be 122m high, nearly 2.5x taller than Falcon 9, and with a dramatically larger volume.
- ogre_codes 6y ago> It's also made cheaply out of steel in a huge garage in rural Texas. This makes it sound like it's made out of old barn roofs and recycled Quonset huts... which would be kind of awesome.
- hinkley 6y agoWell, the test launches have all looked like someone stuck a rocket on a grain silo...
- ogre_codes 6y agoA new or recently polished grain silo.
- m4rtink 6y agoAlso important to note that this is Starship Serial Number 8. If it has an "accident" it's good to know that there is actually a Starship SN9 that has just been completed at the manufacturing base a couple km from the launch site, standing by to take its place and try again. Then there are two more vehicles abou 50% done - just join the tanks and add the pointy part in the front. And parts have been spotted assigned up to SN16! So this is really no ordinary space program where you prepare for years to launch a single super expensive rocket and then deliberate for months or years what went wrong and how to fix it. No, they built the best rocket engine ever, attach it to glamurous 50s SF rocket built from stainless steel (and random Falcon 9/Dragon/Tesla parts) in a marsh and then launch and make more until it can go to space cheaply and reliably.
- TMWNN 6y ago>Tomorrow, SpaceX is going to try to fly the prototype 12.5km up, then have it freefall, falling sideways. At the last moment, it will reorient itself and land on a landing pad. >Or, it will explode stupendously. We got both!