6 ms·
Japan tests explosion-powered rocket for the first time in space (2021)
- tofof 4y agoHere's a video that presents the science behind rotating detonation engines; the article was pretty light on detail. This video is at the other end of the spectrum, clearly intended for other researchers in this domain. Or, if it's over your head (it was for me, at least while trying to wake up), you can still enjoy the pretty damn cool high speed imaging of the detonation waves in this type of engine. https://youtu.be/Ws4kbgfpKCw?t=310 https://youtu.be/Ws4kbgfpKCw?t=310
- zeristor 4y agoDeja YouTube, when you click on a link and find you had watched the first 5 minutes of it two years ago.
- sgt 4y agoNo, the link jumps to that point.
- ragebol 4y agoWoah, exactly same here! Video starts 5 minutes in, so I watched and left off there some time. Wonder what the reason is there.
- ksaj 4y agothe ?t=____ part of the URL sends you to a particular place in the video.
- ragebol 4y agoD'oh...
- arthurcolle 4y agoThe &t=${Timestamp} query parameter links directly to a point in the video
- jvkoch 4y agoThat’s me - that video summarized my dissertation work. I did some follow-on modeling work using neural ODEs that’s pretty neat, too: https://aip.scitation.org/doi/10.1063/5.0063624 https://aip.scitation.org/doi/10.1063/5.0063624
- earthscienceman 4y agoWait. So. I do research in the polar regions and am interested in potential novel power sources for extremely remote environments. Is there any future where this kind of engine could be used for power generation? Say by storage in some capacity? Flywheel. Batteries. Etc. It seems to me it should be possible to detonate\fire when you need to top off your storage but that the design need not be limited to propulsion. Am I crazy? This is so far from my field of work, although I was originally a physicist. Energy density, ease of transport, robustness, and all sorts of other considerations dominate in an environment that is very hostile. Aside from nuclear power (which we will never get) the future is pretty bleak for us still when compared to the diverse technology available in more "normalcy climates.
- GordonS 4y agoAnyone able to provide some info on why this type of engine might be "better"? Is it's use likely to become widespread? Can it be scaled up to propel larger craft?
- dr_dshiv 4y agoI assume because you can use (mini)nuclear explosions in deep space?
- numpad0 4y agoDetonation engines has nothing to do with nukes, it’s just a different way of burning fuel, in a detonation mode/regimen/whatever. Which is I suppose more violent and rapid and efficient, but much more finicky compared to conventional combustion method/type/phenomenon. Sort of like ramjet vs scramjet difference. “I guess that’s better, if you think it can be done, I don’t know though” thing.
- dr_dshiv 4y agoBut the valuable energy density of nuclear doesn’t have a combustion equivalent, right? Only explosions or slow burns.
- numpad0 4y agoI believe nuclear “explosions” are slow burns too, just a sun in Earth’s atmosphere out of nowhere has to cause explosion-like phenomena, and equivalence with chemical explosion can be established. In vacuum it will be just a molten ball. This one uses continuously happening detonation along a circular path, and has little to do with those.
- kortex 4y agoRDEs are more efficient than regular rocket engines. Also, a big part of engineering rocket combustion chambers is balancing power with combustion instability, which can cause flame-out at best, and rapid unscheduled disassembly at worse. RDEs lean into that high energy stochiometric reaction to eke out more efficiency. Due to the tyranny of the rocket equation, even a modest increase in efficiency can greatly increase payload to orbit.
- credit_guy 4y agoIt's not clear to me why they avoid talking about specific impulse or exhaust velocity. When you are in space, this is what matters. If you don't increase them, it's meaningless to say the engine has "higher efficiency".
- api 4y agoHigher iSP is usually what more efficient means for rockets at least in space.
- kbr2000 4y agoThe title lured me into thinking it would be another Project Orion [https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...] :)
- forgotusername6 4y agoI thought this too. Though there is a treaty (https://en.wikipedia.org/wiki/Partial_Nuclear_Test_Ban_Treaty https://en.wikipedia.org/wiki/Partial_Nuclear_Test_Ban_Treat...) which bans nuclear detonations in space.
- dhosek 4y agoI remember reading an Isaac Asimov story where aliens learned that we did all our nuclear detonation on the planet’s surface instead of on space and decide that humanity should be quarantined and not allowed into the interstellar society. Of course living through the decades since Asimov wrote that story, it seems the aliens have plenty of other reasons to keep our species quarantined.
- krapp 4y agoIt's a common trope in sci-fi, but also silly when you consider the scale of space and how radioactive it already is. And then consider that any civilization capable of interstellar travel would already need to be harnessing energies that make nukes look like firecrackers.
- ma11 4y agoThat's the story "Silly Asses," published in 1958.
- fuzzythinker 4y agoWouldn't the ban not make sense if we only use it in deep space instead of LEO?
- 4y ago
- zackmorris 4y agoThat's funny, I was just watching a hobbyist video about rotating detonation engines (RDEs): https://www.youtube.com/watch?v=fRMMSyCcTDI https://www.youtube.com/watch?v=fRMMSyCcTDI I live vicariously through channels like Integza and Tom Stanton. I've wanted to do some of this stuff for over 20 years, specifically electrohydrodynamic (EHD) engines, but spent nearly the entirety of the last 2 decades merely surviving. It's a strange feeling to watch the world make basically no progress over many years, then suddenly go through an inflection point where suddenly everything is solved and there's no way to catch up. Like with flying cars, reusable rockets, AI.. I dunno, I just feel really inspired, but am also mourning the passing of my own life and all that wasted potential. These are all great inventions, super simple, easy to build, but why the heck were we forced to do everything the hard way for so long and still not make rent? These individual projects are really cool, but I worry that we aren't solving the fundamental problem of underemployment that forces fish to ride bicycles instead of swimming freely. Still just a rat in a cage and all that.
- dr_dshiv 4y agoYo, I hear you. Tell me more about the potential of electrohydrodynamic engines. What excites you there? I want to know whether it would be possible to efficiently ionize air and push it with electromagnetic pulses. It just seems so futuristic, you know?
- TaylorAlexander 4y agoWorks for fixed wing planes! https://youtu.be/IorDYGI1uqc https://youtu.be/IorDYGI1uqc
- dr_dshiv 4y agoBut not pushed with electromagnets, yeah?
- TaylorAlexander 4y agooh right! that plane is electrostatic rather than magneto fluid dynamic. good point I totally spaced on that one. MHD stuff is super cool tho!
- zeristor 4y agoScott Manley did a video 2 years ago on rotating detonation gun engines, them being 25% more efficient. More bang for your buck? https://www.youtube.com/watch?v=rG_Eh0J_4_s https://www.youtube.com/watch?v=rG_Eh0J_4_s I almost did mechanical engineering, in my placement before starting a degree I didn’t start I was working with detonation guns to fire tungsten carbide into machined parts to make them last far longer in nuclear power stations. That had finished, just work on jet engine blades.
- legrande 4y agoI always wondered, did we put the nukes on the wrong end of the rockets? I mean a nuclear warhead can cause serious damage, but if you put it behind a rocket for controlled propulsion, we can explore deep space, which is better. Why go to war when we can become space faring instead? It's much more humane, civilized, and less embarrassing as a species.
- louhike 4y agoAs I understand , nuclear power wasn't used for space exploration mostly for political reasons. It's considered quite unpopular to put nuclear engines which fly above people heads. There are therefore a lot of regulations for the use of nuclear propulsion, which has discouraged its use for now.
- roywiggins 4y agoWell, political reasons generally, and the Partial Test Ban treaty in particular. It turns out there's really good reasons to limit the number of bombs detonated in the atmosphere, and for that matter the number of bombs, period. https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
- numpad0 4y agoBecause space settlement could pose a threat to you guys, I mean the US, and also because of cosmic radiation. Habitats with thick enough shield are way too impractical to launch from down here, and must be somehow constructed in space, which is hard.
- YurgenJurgensen 4y agoAtomic engines wouldn't really accelerate space development all that much. I don't see a world where telecommunications, computers and robotics advance any faster than the one we're in from a 1960s starting point. And we're only just getting to the point where automated manufacturing is advanced enough that space industry seems like almost maybe viable. Even if atomic engines let people in the 70s put more mass into orbit, they wouldn't really have the tech to do much productive with it. Plus, a rocket with a nuke on the other end can still destroy a city if you point it in the right direction. There's no such thing as an unarmed spaceship.
- _8j50 4y agoELI5: why don't they use "tiny nukes", basically engineer a small (less than 10cm/1in) nuclear bombs that explode in a chamber at the back of the space ship?
- uup 4y agohttps://en.wikipedia.org/wiki/Outer_Space_Treaty https://en.wikipedia.org/wiki/Outer_Space_Treaty
- deleted 4y ago[deleted]
- MetalLord 4y agoIt was thought of https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu... Now I don't know how feasible is making a nuke as small as you suggest.
- _8j50 4y agoThanks, now i remember hearing about this. > Project Daedalus later proposed fusion explosives (deuterium or tritium pellets) detonated by electron beam inertial confinement. This is the same principle behind inertial confinement fusion. Theoretically, it could be scaled down to far smaller explosions, and require small shock absorbers. That's an interesting tidbit about the size. Also reminds me of the Deadalus spaceship from the stargate universe. But it sounds like politics is the only limit here, surely they can ammend the treaty to allow space-travel work under IAEA supervision.
- foobarian 4y agoWelp, why make a small one then? Just make a big one :-)
- detaro 4y ago- Can't make nukes that small (you literally can't fit critical mass in that size I think, afaik smallest developed ever are 155mm artillery shells) - massive mess if it goes wrong in any way - putting nukes in space is banned by treaty and would be an ugly precedent -Japan has committed to not making nukes and has for obvious historical reasons a difficult relationship with the topic. (If Japan wanted to become a nuclear power, they relatively easily could for a country that doesn't have any, but that would be a major thing and not a side thing of some science project)
- nine_k 4y ago> detonation and compression waves at extremely high frequencies (1 to 100 kHz) Finally spacecraft will be able to produce the characteristic "vvvzzzhzhzh" sound we know from movies like Star Wars. Heard only inside the ship, of course, but likely it will permeate the whole ship while the engine is on.
- ridgeguy 4y agoSort of in the same vein, here's a PNAS report [1] of a continuous combustion detonation engine. No circulating detonation wave, no pulses, just steady combustion in a propellant stream fast enough to stabilize the detonation region at a feature in the engine. Just speculation on my part, but I would think the Isp would be higher than the usual chemical combustion regimes due to higher temperature in the detonation volume. Pretty interesting stuff. [1] https://www.pnas.org/doi/full/10.1073/pnas.2102244118 https://www.pnas.org/doi/full/10.1073/pnas.2102244118
- mrtweetyhack 4y ago
- zeristor 4y agoI was just thinking more about this but wouldn’t a rotational detonation engine impart torque and so spin up a space craft?