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If Rockets Were Transparent [video]
- thatguyagain 6y agoVery cool! For someone who knows absolutely nothing about rockets, this makes it look so much more primitive for some reason. Just these tubes filled with fuel.
- amelius 6y agoYes, we'll have to find a new phrase for "rocket science" :)
- munchbunny 6y agoThat's pretty much what rockets are: massive fuel tanks and a ton of hardware to keep the resulting explosion under control. The really hard part is keeping the explosion intentional and pointed where you want it to go.
- Ididntdothis 6y agoFundamentally the purpose of a rocket is to throw mass behind it very quickly. The idea is pretty simple but the implementation turns out to be quite complex.
- dotancohen 6y agoAs someone who knows quite a bit about rockets, they really are for the most part this primitive. Just these tubes filled with fuel, with a few volts of angry pixies at the top controlling a few degrees of gimbaling at the bottom.
- pjc50 6y agoAlmost all the engineering magic and weight is at the bottom: nozzles to handle very high temperatures, high-pressure high-speed turbopumps, and so on. The falling Falcon stages have the aerodynamic stabilisation of a shuttlecock, and their low center of gravity helps them be stable on fairly small legs.
- twicetwice 6y agoAs others have said, that's basically the case. Most of the complexity, though, is at the bottom, in the engines. Absolutely incredible machines designed to withstand—and control—incredible forces. Turbopumps spinning at tens of thousands of revolutions per second. Insane amounts of heat that need to be cooled so the engine bell doesn't melt. Handling cryogenic fuels (liquid oxygen is very, very cold!) at very high pressures, moving them at very high speeds. One failure mode, out of the many many possible failure modes, that's particularly interesting to me is that if the pressure in the pipes going into the turbopumps (which push the fuel into the combustion chamber fast enough to keep the explosion going) is too low, then you'll get cavitation on the back of the turbopump blades, and the forces from that will destroy the turbopump in under a second. Kaboom. Oh, also, these pumps have to spin so fast that they themselves are driven by essentially little mini rocket engines. For a visual depiction of the complexity of rocket engines, check out SpaceX's Raptor engine, arguably the most advanced engine being produced right now: https://imgix.bustle.com/uploads/image/2020/4/6/c1349369-162d-4430-a789-bad843d8d9ad-eu0suuexqaizgul.jpeg https://imgix.bustle.com/uploads/image/2020/4/6/c1349369-162... I'm no rocket scientist, though, just an interested amateur. Real rocket scientists please correct me if I got anything wrong!
- lutorm 6y agoTurbopumps spinning at tens of thousands of revolutions per second. This is actually not true. These turbopumps are quite large and spin fairly slowly. The design RPM on the F-1 turbopump appears to have been 5500 RPM, for example. (That's not to say they aren't complicated, because they were using 55,000 horsepower to push the propellants into the engine.)
- elteto 6y agoNot all of them! The Merlin turbopump spins at a whopping 36k RPM! [0] https://en.m.wikipedia.org/wiki/SpaceX_Merlin#Turbopump https://en.m.wikipedia.org/wiki/SpaceX_Merlin#Turbopump
- twicetwice 6y ago
- SwiftyBug 6y agoWhat's the purpose of the plane-like rocket? It looks like something that was built to fly in an atmosphere, but it's designed to be in space. Does it eventually re-enter the atmosphere, thus the need to be able to fly in it?
- CarVac 6y agoThe Space Shuttle was designed to be able to steer itself during reentry to a large extent, over 2000 kilometers. This is why it has such large wings. The military wanted to launch it in a polar orbit, gather intelligence, and then land back where it started in a single orbit, which moves 2000 km east of where it was at launch.
- SwiftyBug 6y agoSo it just falls gracefully rather than actually fly?
- Ididntdothis 6y agoIt looked like a falling brick when it landed. The angle it came down at was incredibly steep.
- db48x 6y agoSlightly less steep than the landing angle of an actual brick though. Edit: glide slope is the word I was looking for.
- Ididntdothis 6y agoI watched it come down over Orlando and it looked like this could never work out. Much steeper than any airplane I have ever seen.
- Gwypaas 6y agoReally love this paragraph on the Shuttle Training Aircraft wikipedia page. To match the descent rate and drag profile of the real Shuttle at 37,000 feet (11,300 m), the main landing gear of the C-11A was lowered (the nose gear stayed retracted due to wind load constraints) and engine thrust was reversed. Its flaps could deflect upwards to decrease lift as well as downwards to increase lift. https://en.wikipedia.org/wiki/Shuttle_Training_Aircraft https://en.wikipedia.org/wiki/Shuttle_Training_Aircraft
- wayneftw 6y agoI don't know anything about space or rockets, but... Why is a car housed atop the third rocket? You can see it around 4 minutes after the housing is jettisoned - https://youtu.be/su9EVeHqizY?t=239 https://youtu.be/su9EVeHqizY?t=239 (I was just about to post this question when I decided to just look it up - I vaguely remember hearing something about this - https://en.wikipedia.org/wiki/Elon_Musk%27s_Tesla_Roadster https://en.wikipedia.org/wiki/Elon_Musk%27s_Tesla_Roadster )
- OnlyOneCannolo 6y agoBecause Elon Musk launched his personal Tesla into space on the Falcon Heavy test flight. https://youtu.be/A0FZIwabctw https://youtu.be/A0FZIwabctw https://youtu.be/wbSwFU6tY1c https://youtu.be/wbSwFU6tY1c
- mannykannot 6y agoIf only there were a teapot in the trunk... https://xkcd.com/1866/ https://xkcd.com/1866/
- Yizahi 6y agoMaybe there was. We can't know now :)
- mannykannot 6y agoIndeed, but as Russell himself pointed out, the burden of proof would rest on anyone claiming it to be so!
- deleted 6y ago[deleted]
- wondringaloud 6y agoBecause billionaires with large egos exist in the wild.
- KineticLensman 6y agoNice. If I could change one thing it would be to rotate the different vehicles as they ascend to emphasise that they are trying to achieve high horizontal speed rather than just altitude. That means they are in orbit when the engines cut off, otherwise they would just drop back to Earth.
- SlowRobotAhead 6y agoWhich to me is why it’s crazy these have so much fuel and burn so hard - while Virgin’s “plane” gets as high as it does. Virgin isn’t trying to leave orbit, but it’s still really an interesting comparison to rockets.
- KineticLensman 6y ago> Virgin isn’t trying to leave orbit It isn't even trying to reach orbit. As soon as the fuel is exhausted it cannot help but fall back to Earth because it hasn't achieved orbital velocity. The passengers get a few minutes at high altitude, enough to experience weightlessness and see the stars. It's a suborbital lob, a much more polished version of the X-15 in the 1960s. [Edit - clarity]
- dotancohen 6y agoOrbit requires about 7.8 km/s. That an "s" on the end, not an "h". Orbital vehicles travel almost 8 kilometers every _second_ so as to miss the Earth when they fall. You're right, Virgin's plane gets very high, about one quarter as high as the international space station. But some missions require actual orbit.
- mnw21cam 6y agoYeah. See the first two pictures in https://what-if.xkcd.com/58/ https://what-if.xkcd.com/58/ for an illustration. It only takes a small amount of fuel to reach space. It requires a huge amount to reach orbit.
- asciimike 6y agoOne of the most amusing books I've read on the subject is "Ignition! An Informal History of Liquid Rocket Propellants" (PDF: http://www.sciencemadness.org/library/books/ignition.pdf http://www.sciencemadness.org/library/books/ignition.pdf, Amazon link: https://amzn.to/2WXzWcp https://amzn.to/2WXzWcp), which discusses how science used to be more fun and chemists basically just mixed lots of super dangerous chemicals together all the time to see what worked. Related-ish: https://www.discovermagazine.com/environment/in-russias-space-graveyard-locals-scavenge-fallen-spacecraft-for-profit https://www.discovermagazine.com/environment/in-russias-spac... (again, most rocket propellants aren't exactly great for you).
- tectonic 6y agoLooks like you just submitted it to HN too: https://news.ycombinator.com/item?id=23192651 https://news.ycombinator.com/item?id=23192651 :) Love that book!
- umvi 6y ago> which discusses how science used to be more fun and chemists basically just mixed lots of super dangerous chemicals together all the time to see what worked. Reminds me of the book "Uncle Tungsten", which I highly recommend.
- hoorayimhelping 6y agoRed is kerosene, blue is liquid oxygen, orange is liquid hydrogen, the fuel that looks like fire is solid fuel (think compressed gunpowder). Left to right: Saturn V, Space Shuttle, Falcon 9 Heavy, SLS (still under construction). 2:22, you hear Neil Armstrong say "inboard cutout," that is the center engine shutting off to limit the thrust, and therefore G-forces the astronauts felt. As fuel ran out, the rocket stack would weigh less and so the rocket would push harder. By the time the main engine cutoff, the Saturn V was pulling 4 and a half Gs. Also, just noticed the SLS keeps its launch escape tower (the big needle on the top of the rocket - see this: https://www.youtube.com/watch?v=AqeJzItldSQ https://www.youtube.com/watch?v=AqeJzItldSQ) - this wouldn't happen in a real flight. The flight plan calls for ditching than when it's not longer useful - you can hear the Apollo 11 call saying, "tower jettisoned."
- NikolaeVarius 6y agoWasn't sure why the SLS escape tower stayed on while the S5 was shown jetissoning it
- _curious_ 6y agoGreat info, thanks for adding, you are helping ;)
- bfieidhbrjr 6y agoSo the SRBs don't burn from the bottom up?
- SAI_Peregrinus 6y agoNope, inside out. They're hollow, and the top section has a star cross section rather than cylindrical. The goal is to keep an overall constant pressure for the entire burn time.
- bfieidhbrjr 6y agoTIL. That's amazing, thanks.
- g3e0 6y agoThis really makes it easy to see that the SLS (far right) is derived from the space shuttle, with the orbiter removed and the payload placed on top instead.
- 0xffff2 6y agoIt totally does. I knew this fact already in the abstract, but the imagery in the video really drives home at a more intuitive level just how similar they are.
- dotancohen 6y agoI'm sure that helped reduce the costs and timeframe associated with developing and building it, then.
- d883kd8 6y agoVery interesting for me to see how much shuttle legacy is present in the planned SLS. I knew it was using the same engines but based on the timing here it seems to follow a very similar flight plan with the boosters jettisoned at the same time and the 1.5 stage running out around the same time too.
- LordHeini 6y agoTime to play Kerbal Space Program again :)
- unnouinceput 6y agoThis animation doesn't do enough credit to Saturn V. Tell me again off them 4, which one carried people to the moon and back?
- NikolaeVarius 6y agoNone of them. The Saturn 5 was discarded after launch.
- dotancohen 6y agoThe S-IVB performed the TLI maneuver. And by any definition, the Saturn V carried the entire stack into orbit. From orbit you're halfway to anywhere.
- dotancohen 6y agoThat is not the purpose of the video. I worship the Saturn V as much as anyone, seriously not a week goes by that my kids don't hear a story out of me featuring that rocket, but the video does it's purpose. If you really to give more (rightfully deserved) credit to the Saturn V, then in fact you can see how much more payload and propellant is on top of the still-firing S-IVB at the end of the video.
- marmshallow 6y agoI'd also love to see a comparison of the rockets' altitude & velocity thru the launch
- onemoresoop 6y agoI enjoyed this with my 2yo son. He loves rackets and calls them Kiko. Surprisingly he had the patience to watch the video till the end:) Thinking back, I was quite fascinated by rackets and only when I was 7-8 did I get across a book on rockets with very colorful fold out posters in it. I think it’s great to have all this educative material on youtube, I will curate some cool playlists for him to watch and learn things.
- gloopyfork 6y agoI have always wanted to see this! Intuitive visualizations of engineering marvels are in short supply, and rockets are one of those tech that operates outside everyday (physics) assumptions. https://www.youtube.com/watch?v=su9EVeHqizY https://www.youtube.com/watch?v=su9EVeHqizY Since space-capable launch is generally “dual use” for ICBMs, watch how the end of the world as we know it proceeds by the beautiful operation of precision engineered machines.
- ardy42 6y agoThe Saturn V and SLS engines burn for significantly longer than the Falcon 9 Heavy's. What's the significance of that? I assume it means they can lift more into higher orbits, but I'm not sure.
- oconnor663 6y agoThe Saturn V and the SLS are as big as they are because they're designed to carry astronauts to the Moon (or farther). I don't think the Falcon Heavy can do that without using multiple launches and meeting / refueling in orbit.
- Robotbeat 6y agoFalcon Heavy could do a single-launch loop around the Moon with Dragon.
- lutorm 6y agoThe animation of the FH appeared to show that the Mvac on the second stage cut out really early. I don't think that's accurate, SECO on the FH demo flight with Starman was at about T+9 minutes.
- mr_toad 6y agoIt’s easier to recover the boosters when they are moving slower.
- Nokinside 6y agoSaturn 1 (SA-5) Camera Inside Kerosene Tank https://www.youtube.com/watch?v=fL-Oi9m2beA https://www.youtube.com/watch?v=fL-Oi9m2beA
- SeanFerree 6y agoVery cool!
- shadowgovt 6y agoIt's fascinating to observe how little fuel is left in the Falcon Heavy lower stages when they're jettisoned. That reentry profile really gets to take advantage of atmospheric drag to sink all that kinetic energy.
- SergeAx 6y agoSolid rocket boosters of Space Shuttle and SLS are quite similar indeed: https://en.m.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster https://en.m.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_B... https://www.northropgrumman.com/space/nasas-artemis-program/ https://www.northropgrumman.com/space/nasas-artemis-program/
- gorgoiler 6y agoThis is wonderful. I’ve never really understood how solid fuel boosters work. Are they filled with something granular like sand, that empties down the rocket tube? The video makes it seem as if the entire tube is on fire at the same time. It’s also fantastic that an asymmetric vehicle like the Space Shuttle was ever built. What an outlier it seems, amongst the more, I suppose traditional looking rocket designs in this video. A very poetic leap, as well, to think that the same orbiter that climbs under so much power is the same vehicle that glides into land without power, all the way back from orbit!
- franzb 6y agoAs I understand it, the solid propellant is hard and hollow on the entire length: https://en.wikipedia.org/wiki/Solid-propellant_rocket https://en.wikipedia.org/wiki/Solid-propellant_rocket. Also check this wonderful Applied Science video: https://www.youtube.com/watch?v=TLPWqCMb7DE https://www.youtube.com/watch?v=TLPWqCMb7DE
- nickik 6y agoIts not really like sand, its more like toothpaste that is dried up. Its essentially a rocket fuel where the fuel and the oxidizer is premixed in the same 'paste'. This makes clear why its a pretty dangerous substance. You need to be very careful manufacturing those, as they can explode pretty easily. The way it works, is that it burns from the insight out, like a hollow candle. The trajectory of the booster is basically molded into the hole in the middle. Once you light in on fire, the booster is gone fly its trajectory whatever you do. Here you can see all that pretty well: https://www.youtube.com/watch?v=k_JULlA_9Mo https://www.youtube.com/watch?v=k_JULlA_9Mo
- akincisor 6y agoIf you've ever used a firecracker rocket it has solid fuel in exactly the same way. It just burns from the inside out (I think) to ensure that the rocket's center of gravity doesn't change as the burn progresses.
- PostOnce 6y agoThis is my all time favorite animation of how a solid rocket works https://i.imgur.com/E7J8pxF.mp4 https://i.imgur.com/E7J8pxF.mp4 so yeah it is all burning at the same time In the OP's video, it looks like the fire is magically coming out of thin air... it'd be hard to do the animation style I linked at the distance in OP's video though, so I'm not sure how they could better animate a solid fuel rocket
- deanCommie 6y agoAlways a good reminder, what people think about as "rockets" is really mostly fuel tanks. I mean intellectually people know that. Rocket = "Engine" + "Fuel tank". But I still think that when people are imagining the awe-inspiring power of a massive rocket carrying humans into space, they're not dwelling on the fact that the majority is just a big cavernous vessel for fuel.
- apatheticonion 6y agoAre reusable rockets more cost effective than disposable (or recoverable by parachute) solid rockets?
- 205guy 6y agoAnd another TIL from reading the comments on the video: "Question: Are inertial forces required, and incorporated into the designs of rockets, in order to keep liquid fuel at the bottom of each tank?" Reply: "They are in constant acceleration except when staging or after a shutdown before a re-start. They use ullage motors to accelerate the rocket just enough to settle the fuel (either small solid rockets or reaction thrusters) when they are in zero g." Reply 2: "Apart from Ullage Motors you can also do "Hot Staging" where you light the next Stage while the current one is still burning. That's why a lot of Russian Rockets don't have this open Interstage Sections where you can see the Engines instead of Interstage Fairings." https://en.wikipedia.org/wiki/Ullage_motor https://en.wikipedia.org/wiki/Ullage_motor
- ashtonkem 6y agoSome rockets also pressurize their fuel tanks with Helium for similar reasons I believe, including the Saturn V.
- boublepop 6y agoContent like this and the amazing contributing comments here is what I love most about the internet. When I woke up this morning I did not expect to spend hours reading and watching videos about space rockets, but here I am all the merrier for it. Thank you!