Explaining Fusion Engines in Realistic Sci-Fi

Spacedock delves into the intricacies of fusion engines as applied to sci-fi space travel.
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Spacedock does not hold ownership of the copyrighted materiel (Footage, Stills etc) taken from the various works of fiction covered in this series, and uses them within the boundaries of Fair Use for the purpose of Analysis, Discussion and Review.

[@Spacedock]

Get "Designing the Perfect Space Fighter - A Spacedock Reference Book" here! www.patreon.com/posts/77243474/

[@hellacoorinna9995]

7:52 Project Orion

[@domenicoazzia4153]

Question. How would fusion engines work i the Mass Effect universe? Considering that element zero can lower the Mass of the ships and even create gravitational fields, how would this affect the performance of the fusion drives as well as those projects you talked about in the video?

[@90lancaster]

I Don't need Science... I have the power of Imagination !

[@BS-vm5bt]

@@hellacoorinna9995 Would we not call that a pulsed fission fusion engine. Since it uses fission as the initial stage to create the fusion reaction with hydrogen bombs.

[@gePanzerTe]

@@domenicoazzia4153 As Mass is the real issue in Our Universe, reducing the influence of mass would reduce the energy cost of very high speeds (~ > 75% of c (light speed in vacuum)) 🚀

[@wild_lee_coyote]

Interesting fact: fusion has a declining return on power output the heavier the elements you use. Fission on the other hand has a diminishing return with the lighter the element you use. There is a point where both fission and fusion return less energy than what you put into them. That point is the element Iron. The element where nuclear power dies.

[@Talon1124]

Nuclear power is a fey creature confirmed.

[@3Rayfire]

The Element that kills not just fairies, but whole suns.

[@mackenziebeeney3764]

Explains why fusing molecular hydrogen into helium is the ideal. Sadly molecular hydrogen is an extrovert and demands friends.

[@lawrencedoliveiro9104]

And yet the elements heavier than iron had to have been produced in fusion reactions in the first place. When a star dies in a supernova, the massive amounts of energy released can achieve some wonderful things ...

[@johannageisel5390]

@@lawrencedoliveiro9104 They do it so that we can then dig up those elements and fission them again, harvesting the energy of long gone supernovae and neutron star collisions. :P

[@MrQuantumInc]

If you can bend space and time for the sake of faster than light travel then you can probably produce fusion by simply condensing the space around the fusion fuel until it achieved the pressure of a star. If you can produce gravity artificially under the floors of your ship just for comfort and health of the crew, then you can focus that effect onto a piece of fusion fuel.

[@sadiqahmed4143]

If you can bend space and time for FTL you can bend it for Subliminal travel as well

[@gulliverdeboer5836]

Unless you need fusion power for the energy requirements of spacetime bending in the first place...

[@kronosbot5]

I can only imagine how much energy would be needed to be spent on just getting a matter/anti-matter drive to not destroy itself.

[@mattstorm360]

In Mass effect, they even used the ability to manipulate gravity to create super dense materials armor.

[@sadiqahmed4143]

@@gulliverdeboer5836 you probably do need A lot of energy

[@cyborghobo9717]

Projectrho is strong with this one .

[@supermega10453]

I love projectrho!!

[@supermega10453]

I love projectrho!!

[@cyborghobo9717]

​@@supermega10453 hooj even snatched Winchell's catch phrases like "every gramm counts" and "hummingbird fart " .

[@hoojiwana]

A shiny coin to who can find my name on the site. - hoojiwana from Spacedock

[@thatstarwarsnerd6641]

@@hoojiwana ‘And thanks to the many playtesters, including but not limited to Canopus (first test pilot for Project Orion), SufficientAnonymity, Markarian421, s20dan, Vaccer, Mecha Pants, Rune, lyndonguitar, zirgon, mushroomman, khyron42, Fyrem, czokletmuss, Leonov, and *hoojiwana* .’

[@Stukov961]

Crossing my fingers for a video about a nuclear salt water engine. The probably most insane, but achievable, engine concept ever devised.

[@killman369547]

Ah yes. The engine powered by in essence a continuous nuclear explosion, it's perfect.

[@anuvisraa5786]

I use a variation whit an external neutron source in one of my settings as the main propulsion system

[@scifirealism5943]

Scott manley made a video on this.

[@CptJistuce]

You know it is a good design when it makes Project Orion look relaxed and leisurely.

[@koiyujo1543]

the engine that could be that similar to the epstein drive from the expanse the vid from scott manly did talk about that

[@IncoherentOrange]

Terra Invicta puts a lot of effort into implementing all sorts of propulsion mechanisms in for the player to develop and use on their ships - for good or bad. Yes, you can have an Orion-based design, lots of crappy ion engines, or eventually work your way up to actually good inertial confinement drives.

[@BS-vm5bt]

Why not the neutron flux/tourch drive fission technology is far to underestimated. I could build an engine with 4g acceleration with 1K delta V. I mean we can even build a nuclear dusty plasma engine with 1.5 million ISP.

[@Just_A_Simple_Time_Traveller]

Read that as Onion-based design, was very confused.

[@mrsuspicious1743]

@@Just_A_Simple_Time_Traveller The onion of defense has expanded to include propulsion!

[@IncoherentOrange]

onyo

[@crashstudi0s]

@@mrsuspicious1743 I mean, they certainly can't kill you if they can't catch you

[@oliverdemille8388]

I love the depiction of "Cosmic Rays" :)

[@AnythingMachine]

The Epstein drive is not absolutely impossible in the sense of contradicting physics to build a fusion drive that efficient, as you just need to ensure that the reaction is external and confined in a magnetic bottle behind the ship so that almost all the waste heat just radiates into space, then the rest can be handled by spraying dense hydrocarbon slush or water or something into the exhaust plume. Though some commenters have questioned whether the various tech assumptions with regard to fusion gain and efficiency improvements are reasonable. Basically if you buy, * Exceptionally powerful magnetic confinement at multi-hundred meter ranges * Either incredibly powerful fusion ignition lasers (very brief exawatt pulses) or incredibly high gain factors based on far future discoveries about the dynamics of fusion implosion Then it works. Both of these are not what I'd consider handwaves since they're not outright breaking any physical laws - they're things we don't know how to do, can't demonstrate are impossible, but that we can predict the physical consequences of. Of the two, the more reasonable is the magnetic confinement, because we need maybe only a 1 order of magnitude improvement in the parameters of the superconductors (critical field) rather than 6 or more orders of magnitude improvement in fusion gain factor. Both are physical phenomena that we either don't know the governing laws for or are too computationally complex to model, so what the upper limit of fusion gain factor is for a particular implosion design, or what the highest critical field superconductor in existence is, we don't know. But even if this is how the Epstein drive works, an Epstein is putting out about as much energy as an antimatter beam core drive only without using antimatter and so the exhaust beam should not look like a normal rocket engine like it does in the show, but rather like a ravening gigantic solid lance of death as with the venture star.

[@LordOceanus]

You are right on the money. Thats the same philosophy I subscribe to. Ships in my writing are equally deadly from behind if you are too close when its at full thrust. Although I stick closer to the upper end of Fusion power rather than tipping over into antimatter territory since I find antimatter, real and plausible as it is, not very fun. It just makes it all too easy

[@fabiosilveira8571]

Tbf they did teased huge radiation spikes when some ships decided to dump their cores, ships descending into atmospheres tend to not decelerate using their main engines in order not to glass their landing sites, and even the engine of a small shuttle managed to completely torch a small chunk of Winnipesaukee Island. I still think they dialed it down a lot considering that drive plumes were sometimes described as stretching for distances a few times greater than the ships

[@vtrbswarmachine]

That's why I think the concept of ship to ship Battle in any means is almost nonsensical. The radiation alone. Carriers that can deploy drones/Corvette class un manned recon and full battle means. That's the way. Way out of the harm zone and able to scuttle or lose weight without operation (human) losses. Heh. If we ever see contact it ain't gonna be from an actual alien. It's gonna be from an alien scout. I digress. Welp went of course. Enough for me.

[@petersmythe6462]

I would call those *handwaves* but not *Clarketech* or *magic.* On one end we have ultrahard sci-fi. Unless there is a clear technological path to allow something to exist in the setting, it doesn't. No Epstein drives here. There can be fusion drives but they should be constrained by the known, relatively conservative principles of physics, engineering, economics, etc. This is one step from being able to go to a company that makes relevant tech and actually pitch the idea to build whatever thing if you had a big enough budget or a good enough reason. Example: nuclear weapons as imagined in 1939. Handwaves are things that the author gives up on providing a full explanation because they don't know how or if the thing could work but the basic mechanism for it is there. High thrust Fusion-torch powered crafts are applying unknown and optimistic extrapolations of current tech or known science to achieve a result which is not known to be feasible but can at least be fully described. The laws of physics constrain the setting although they are not used in a conservative way but in a way that would say least scare away engineers from saying "yeah, I could build that with 20 years is research and a billion dollar budget." Example: nuclear weapons as imagined in 1933. Clarketech is where some piece of handwavium tech just *is.* FTL or teleportation or time travel (which are actually the same thing) Isn't based on exteapolating faithfully from some carefully considered technobabble. The technobabble is *purely* a retroactive justification. But at the same time, they are not *obvious* violations of known physics if you read the fine print. General relativity does permit distortion of space and time in ways that allow for those kinds of things to apparently occur. We have not even the slightest inkling on what principles those things can occur, but we cannot conclusively say it is impossible with great enough negative mass and such. Indistinguishable from magic, but both presented and conceived of as ultratech. The setting is justified retroactively with a nod to the most speculative and least practical of physical theories if at all, and presents technology incomprehensibly advanced as a solution. Example: nuclear weapons as imagined in 1916. Next we have magic. At this point, the setting is only constrained by consistency if even that. Blatantly unphysical things can occur and there will be no technobabble about how this could take place in OUR universe or is even permitted under known science. Example: a dragon that breathes nuclear-scale weapons as imagined in 1800. Finally there is powers as the plot demands. In which the setting itself is taken over by the plot. Example: Mary Sue can make nuclear weapons appear out of thin air because of course she can. You just don't comprehend the full power of someone who for the last three books was just a badass normal with no indication of conjuration abilities. There is no need to explain or limit this power because internal consistency of the setting has itself been abandoned in order to railroad the plot.

[@ryuukeisscifiproductions1818]

@@vtrbswarmachine no not really, because missiles are better. in space drones lose out to missiles, and in combat distances with significant relativistic time lag and light speed limited communications, drones would literally be nonviable due to seconds or minute long time lag from the operator to the drone. and in space, carriers would just be vastly less efficient arsenal ships/guided missile battleships. and in the sensor friendly environment of space, Recon can be achieved by simply using larger and more powerful sensors mounted on large ships. A drone would offer no advantage in recon to just simply having a huge sensor array in a scenario where both comms and sensors are limited to lightspeed.

[@salamanda550]

"Has advantages, such as not needing gigantic radiators" I don't know that kinda sounds like a disadvantage to me XD

[@killman369547]

No, not needing exposed radiators that can easily be shot to bits is a good thing.

[@fast-toast]

How is that a bad thing? Radiators keep a craft from getting to hot. Big Radiators add weight and in a combat setting, are big targets.

[@mattiasdevlin1363]

You missed the most obvious alternative of electric confinement fusion or Farnsworth-Hirsch fusor. This design works like an ideal fusion engine from the start (very little modification needed of the reactor) and can be fed with B-11 and hydrogen to produce a fairly clean fusion process with only helium/alpha particles as a side product. It could theoretically have insane specific impulses and pretty good thrust to weight ratios.

[@joshpord]

Suggestion topic: asteroid mining Examples: EVE Online, The Expanse, Don’t Look Up

[@mitwhitgaming7722]

What's funny, the real money in asteroid mining would be water to turn into hydrogen fuel or simply to use as drinking and irrigation water on a potential colony.

[@lazyremnant380]

I'm very late to the party, but I just wanna say, if you want to use high-thrust fusion engines in your setting while still making it sound realistic, you can limit it to Solar System only. We don't really need more than a few hundred km/s of exhaust velocity even to Pluto; we don't have enough time to reach higher velocity before the flip-off point is reached. Since fusion engines are capable of spewing its byproducts up to 1000 km/s, we can easily trade some excess velocity for higher thrust.

[@The--Illusion]

Could you do a video on exotic sublight engines? Things like Star Trek's impulse engine are exotic due to their function being very different from other drives, either due to the engine itself or due to other mechanisms (like the impulse engine is plasma directed to the needed port instead of just dumped out the back)

[@3Rayfire]

Impulse engines and Mass Effect's engines could go in the same video.

[@yourfriend8052]

Fusion thrust ports aren’t really exotic

[@lanteanboy]

Impulse engines are just a fancier name for their Fusion Engines

[@scifirealism5943]

I could talk about that.

[@kaitlyn__L]

@@lanteanboy they also involve “low level warp fields” to increase the thrust by a few orders of magnitude. That’s the exotic part.

[@Cuberay1701]

Another interesting concept is the VASIMR-engine which is basically a rocket engine with a gear shift (I hope I found the correct translation). This "gear shift" enhances the engines propellant efficiency as you can adjust the drive to the situation you are facing. The concept isn't specifically designed for fusion but it can be used to power the engine and boost its thrust.

[@srbrant5391]

For my novel, I’ve come up with spin-polarized fusion engines with antimagnetic nozzles to keep their magnetic bottles from interfering with each other, since they’re often bundled together. In addition, I was thinking of adding a little handwavium by using gravitic repulsion to squeeze reaction mass out at a faster speed, increasing efficiency.

[@BUTTER-oc5gs]

if youre worried about the specifications of a ship, while writing a story, i doubt your story is going to be worth looking at in the first place

[@srbrant5391]

@@BUTTER-oc5gs Well excuse me for making an effort.

[@salguodrolyat2594]

​@@BUTTER-oc5gsmaybe the specs of the engine is part of the story.🤔

[@antonberkbigler5759]

So, as part of an extremely expansive crossover AU I made a concept for a fusion reactor+engine that would have been made by Aperture Science. The key thing to remember with them is that although they are extremely smart, they also happen to be tremendously stupid and silly. So, the reactor part of it essentially used highly complex gravity fields to house an artificial star, with two exit points at the poles. Extremely energetic jets of fusion plasma would be emanated out of the artificial star and then piped into a series of pistons, literally just steam locomotive pistons in regards to design. Those pistons were hooked up to either solenoid or dynamo generators, but that’s whatever. This version of Aperture Science didn’t have anything strong enough to make turbine fans that could withstand fusion plasma, but they did have concepts for having twisted magnetic fields to create a sort of magnetic turbine fan in later iterations of this fusion reactor. The plasma would then be routed to a thruster mostly as just a way to utilize exhaust since they can’t just dump it Willy nilly like steam exhaust, but there is a sort of 'afterburner' system that would create a complex linear gravity field to fuse the plasma an additional level up the stellar fusion chain. Main reactor fuses hydrogen to helium, afterburner fuses the helium together.

[@SammyWhiteley]

It needs to use ASHPD-like portals to control thrust. The bigger the portal, the higher the exhaust.

[@antonberkbigler5759]

@@SammyWhiteley Using it as a thruster deliberately didn’t cross their minds when designing it, that was an afterthought lol. They were just gonna vent it but due to the high speeds of the plasma even just venting it with no nozzle caused acceleration.

[@tyrannicpuppy]

One thing I found myself super curious about by the end of The Expanse was what would it feel like to be inside the moving drum of the Nauvoo during the originally intended journey to it's new star system? Because you get gravity along the length of the ship via the engines thrusting forwards, which presumably needs to keep happening through the entire trip for it to take even a remotely reasonable amount of time. And rotational gravity in the drum via the spinning of the drum. So would you have two different sets of gravity pushing you against the outer edges of the drum and also feel like you were constantly being pulled in the direction of the engines at the end as well?

[@lazyremnant380]

Realistically, the Nauvoo's crew should've got pulled to the drum's "lower corner" as a result of the vector sum between two accelerations (one perpendicular to the ship's axis, and one parallel to it). A neater way of doing it is to make it so that only one source of artificial gravity is active at any one time. Avatar's ISV Venture Star's solution is to fold the hab drums parallel to the thrust axis, so when the ship is under thrust, they got pulled to the engines, and when the ship is coasting, the drums open up and become centrifuges. That leaves them with the problem of transient weightlessness when the drums are transitioning from one mode to the other, but I guess it's just trivial matter😅

[@mryellow6918]

I'm assuming the original idea wasn't to have it accelerate the whole 100 years

[@montecorbit8280]

At 5:55 "....greater than a hummingbird's fart...." That was pretty good, I had to stop and laugh at that!! Thank you....

[@0326jlc]

I literally had this wait a second and process why is the spell jammer,(a giant magical, manta ray that swims in space in D&D )was an episode about fusion. Cosmic rays I go to bed now.

[@LordInsane100]

Yeah, as cool as OG Spelljammer was, I imagine Spacedock wouldn't have that much to say about something where magic is the explicit answer to almost every question.

[@rommdan2716]

@@LordInsane100 Why? It's cool!

[@Tigershark_3082]

Spacedock is unironically one of my favorite youtube channels currently! I was wondering: if you folks could make your dream air force (can use already existing aircraft or design your own), how would you make it? Also, what would be your dream realistic fighter jet (invented from the ground up)

[@Blastxu]

The X4 soundtrack was a good choice for this video!

[@MaxterandKiwiKing]

Which track!? Please I must know

[@connortron7965]

Always love seeing starsector clips

[@richardrothkugel8131]

I'm working on a space game and I was using spaceship hulls that had about twice the mass of modern Navy warships (between 7000 and 14000 tonnes) on account of shields, plating and additional technology. I was planning using fusion reactors with ion thrusters as a baseline and found that constant thrust between 5000 and 30000 newton was the sweet spot for acceleration in my environments. Glad my calculations were on point.

[@Dushess]

You need huge thrust to move such amounts of mass in reasonable time. Only (sci-fi) modified ion thrusters is able to complete this.

[@TheTrueAdept]

The radiation problem is heavily dependent on the fusion reactants. For example, a Dual-Deuterium fusion spews out high-energy neutron radiation like a hose, Deuterium-Tritium makes Dual-Deuterium look like its completely safe, a Deuterium-Helium 3 fusion reaction produces less radiation than a dual-deuterium reaction but enough you'll need some protection, a Dual-Helium 3 reaction is pretty low on the rad-charts but requires quite a bit of Helium 3 to function, and the masterpiece of fusion though is the proton-proton chain (aka what stars use) which uses good ol' protium (aka atomic hydrogen) and doesn't spew much in terms of radiation in the initial reaction. In several of my settings, the various factions use a fusion rocket based on the GURPS High-Efficiency Plasma Recombustion Fusion Rocket (basically a fusion rocket similar to the Epstein Drive from the Expanse in that its propellant-efficient, though instead of hydrogen propellant, they use water) that uses dual-helium 3 reactants or the incredibly hard-to-kickstart proton-proton chain, which are far lighter than other fusion engines.

[@MRNBricks]

Kudos on correctly using Saturn vs Jupiter for the location of the monolith. 👍🏼

[@versinussyrin577]

Magneto-inertial drives also have a second, similar variant The magnetized target fusion one But the principle is the same. Use mass to squash mass until it fuses. So instead of using lithium foil, you can use deuterium to squash deuterium to fuse, by spitting it at the plasmoid in the middle at high velocities, then throwing some propellant on it afterwards. This version can achieve high thrust for its efficiency. (for any inaccuracy i apologize) I love Atomic Rockets, and how its author, Winchell Chung writes it

[@kevinshepardson1628]

As a bonus, this also counts as a video on sci-fi weapons, per the Kzinti Lesson.

[@Timmycoo]

Yay I'm glad you touched on this topic. Scott Manley did a really interesting video on it as well so this got me hooked.

[@hoffenwurdig1356]

This video is excellent. For completeness, I should point out that in the 1995 computer game called "Mission Critical" by Legend Entertainment, the description and portrayal of the US Navy deep space light cruiser Lexington is impressively rigorous. The Lexington has a chemically-powered orbital maneuvering system and four aft-mounted fusion engines. The engines are fed via linear accelerator on the centerline of the vessel. It drives deuterium and tritium fuel into a pressure vessel, where inertial confinement fusion occurs via compression lasers. If I remember correctly, the Lexington is capable of a maximum acceleration value of 7 gravities when it is in normal space. The habitat module has the decks oriented in the proper direction relative to the axis of thrust. The vessel's exact dimensions are not stated, but I estimate the Lexington to be 260 meters long with an 88-meter beam and an 85-meter draft. The vessel is designed to be very fast, lightly armored, and heavily armed -- with a typical crew of 20, a maximum crew capacity of 25, and a primary role based around the employment of up to 18 unmanned combat space vehicles. She also has a few close-in weapons for use if things do not go according to plan. There is no magical inertial damper technology in the game. The design of the ship does have several intentional departures from scientific realism for narrative reasons. It includes an FTL jump drive and omits temporal dilation. Furthermore, the Lexington is depicted as deriving its electrical power from a pressurized-water nuclear fission reactor, similar to those found on modern submarines. This portrayal is unrealistic for a ship authorized by Congress in Fiscal Year 2111, as one would expect the Lexington’s power reactor to likewise be of the nuclear fusion type. I believe that departure was likewise for story purposes, so as to have a way to create dramatic tension through the danger of a power reactor meltdown once the Lexington becomes severely damaged in battle.

[@SpazzyMcGee1337]

What a great starter too all the different fusion types.

[@coreyjblakey]

This video beautifully sums up some research i needed to do for a project of my own. Thank you so much 😂❤

[@pbwc781]

The one thing Star Wars and Star Trek & a lot of others have always gotten wrong is, there is no top and bottom in space. The Expanse got this right. On an ISD in REAL space would look weird on its side and dumb reversed with the mast on the bottom. The Borg Cube starts to seem to be the most logical design. How weird would it be to approach the Galaxy Class with the saucer section on its side or on the bottom? These S.T. & S.W. ships all are based on the idea of surface water ships. The Expanse corrects this very well. Almost every ship is based on the principles of this very argument.

[@iamunamed5800]

It would be awesome to see a similar video to this about fission drives!

[@agoose-pm7ij]

I'd be very interested in seeing a video about planetary defenses, concepts of orbital defense platforms or ground to orbit gun/missile battery's and such. I've always thought building sized artillery is bad ass.

[@HopeisAnger]

Many years ago, I learned a single round of .40 s&w releases ~2,000 newtons of force on impact. Which adds some perspective to this.

[@DrownedInExile]

Sounds like theoretical fusion drives would need to be paired with a less-efficient but high-thrust system. Perhaps a launch platform orbiting Earth would serve that need, while the fusion engines take care of the long-term voyage.

[@heavyarms55]

For me the biggest thing in sci-fi isn't that it needs to conform to the real world and what would work in real life. For me what matters more is that it establishes and follows consistent rules within its own setting. Sci-fi is Science FICTION. I have no issues with a fictional story making up its own rules. But I do want them to follow the rules. Don't waste our time setting up something JUST so you can break it later. If you want to just disregard a real world limitation, fine. But then you have established how it works in your setting. Now THAT is how it works. Be consistent with that rule. I love the Expanse and have read the books several times each. I feel they do a very good job of being consistent within their own fictional setting. Star Wars is another personal favorite but a great example of failure to do this. As depending on the movie or book and even sometimes within the same story, the rules of spaceflight and what ships can and cannot do, are not consistent. Hyperspace and the hyper drive are fictional concepts and how they work and what they can do is not consistent across the franchise and it annoys me.

[@scifirealism5943]

YES. SO MUCH THIS

[@WolfeSaber9933]

I see the fusion drives in the Expanse to be aneutronic. The ball is very solid and in the same season, a bunch of colonies were making a big deal outbof their mined lithium. The beams would be proton beams causing the reaction. The alpha particles could be used as the thrust.

[@mihan2d]

Unlikely the alpha particles alone are enough, the characters mentioned reactive mass a few times meaning that it, probably hydrogen, is likely pumped through the reactor (alongside a closed cooling loop) to capture its heat and then as it heats up and expands is thrust out the nozzle, most likely additionally accelerated by the magnetic coils. Given how efficient Epstein drives are, likely they use all available means to turn that fusion energy into thrust.

[@WolfeSaber9933]

@@mihan2d alpha particles are helium atoms without electrons.

[@mihan2d]

@@WolfeSaber9933 I know. But you need a lot more reactive mass than just reaction products to achieve anywhere near desired thrust and efficiency especially given how Epstein drives aren't supposed generate a ton of waste heat

[@Zacho5]

@@mihan2d They use water as Rmass. The RCS uses water heated up by the reactor into stream. Least from the books.

[@leerman22]

I have this theory that they use deuterium or heavy water for reaction mass to do a second fusion reaction in the engine itself, getting the fire of the fusion reactors inside their ships to get the job done. Probably makes sense because Epstein didn't sound like he made major changes to his yacht.

[@RS8XB]

I look forward to this great content

[@pkscolax9480]

Cool video, SpaceDock!

[@philrm99]

Excellent discussion

[@FinGeek4now]

I imagine two stages, though, not how we think of rocket stages. The first stage is the burn stage in which we use fuel and burn it to start moving the craft and gaining initial thrust. The second stage is the cruise stage in which we use our fusion reactors to power massive ion drives. That, more than anything, would be the ideal solution (I think, as far as near-term technologies go). Also, fyi, we wouldn't discard any of the stages in this, since they're just two different types of engines which move the ship and they rotate which ones are on/off depending on the situation and "stage".

[@TotallyDapper]

Man I got here early. :) This is a cool look at fusion engines!

[@safiulina1]

For the "Zeus-nuclon" nuclear tug, the use of thermonuclear fusion was being worked out as an increase in thrust. Since in order to increase it is necessary to increase the temperature. But so far we have settled on rotary magneto-plasma engines.

[@sebsunda]

LOL!!! Those Cosmic Rays are of EPIC proportions!!!

[@johnpluta1768]

Add centrifugal force to a fusion reactor would be very efficient in terms of mechanics

[@starlord3286]

Laser-style linear magnetic plasma camera is really smart, I've never seen that before

[@TheStig827]

If you're not familiar with it, the anime Outlaw Star has a focus on "grappler ships" that basically got started as tugs/utility craft until pirates got good at fighting with the manipulator arms. The hero ship is a high performance grappler ship.

[@rommdan2716]

Oh yeah! The Reactionless drives video it's getting closer and closer!

[@aurance]

Haha that cosmic ray graphic… 05:39

[@jonathanbaincosmologyvideo3868]

very nice perhaps have a look at the 'Astrosling'

[@scarecrow108productions7]

3:31 You know, I'd give anything to see you feature some insights on all the Spacecraft/Stations from For All Mankind, such as: *Lunar-modified Space Shuttles* *OV-2XX Pathfinder-class NERVA Shuttle* *Helios Phoenix Interplanetary Spacecraft* *Mars-94* *Sojourner-1* *Jamestown Lunar Base* *Zvesda Lunar Base*

[@Allan_aka_RocKITEman]

Great video...👍

[@MattiaMonticelli]

I approve the X4 ost as background.

[@RJ_Ehlert]

Nice video.

[@Anti_Woke]

Fascinating as this all is, it really gets the seal of authenticity by being illustrated in Kerbal Space Program 😉

[@realVertiqo]

I want The Expanse back... :/

[@TheGenericavatar]

A more recent of fusion ignition system uses 'small', opposing linear particle accellerators to create the heat and maybe pressure for nuclear fusion (I forget the exact details at this point). They can start and stop the fusion process many times a day. It uses an unusual, compact super conducting linear magnet design that has been known for years but almost never used.

[@Croz89]

I guess one of the biggest challenges for that is extremely precise beam alignment, off by the tiniest amount and the two particle beams miss each other and no fusion occurs.

[@spark5558]

​@@Croz89Hellion said there biggest problem is that the chamber melts

[@archerbascha8757]

The USS Sulaco from Aliens uses industrial diamond dust as reaction mass for the fusion engine.

[@cfoa13]

more video like that will be nice

[@glist119]

I don't care what video about. I see The Expanse - I press like

[@mitwhitgaming7722]

Fusion engines only makes me think of the end of Halo where they blow up the Pillar of Autumn to destroy the ring. Now when I see that scene, I think of how a weaponized fusion engine would essentially create an artificial star, not too far off from what we see in the cutscene.

[@dvrchweesse1frfdozemkaanai594]

Now imagine if that engine were antimatter instead of fusion

[@dunmermage]

"A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive." - The Kzinti Lesson, Larry Niven

[@stompyrobutts]

@@dunmermage fuck thats a thought ive never had before

[@26th_Primarch]

​@@stompyrobutts It's basically a ship sized lightsaber.

[@wildcardbitchesyeehaw8320]

Fusion reactors can't really blow up like they do in popular scifi

[@R4d6]

One thing to note about the IRL fusion : While they did manage to "produce" more energy than they "put in", they didn't manage to extract said energy, nor was the goal being actual power production. And the energy that they "put in" ? That is referring to the laser doing the actual fusion, not all the electricity that went into making the laser and powering the machinery. TL;DR : It was not power-positive by a long shot, and the goal wasn't producing power anyway.

[@spark5558]

Well no overall energy put in was greater than what they got out The energy that actually did the fusion was less than what they got out

[@R4d6]

@@spark5558 That's basically what I said.

[@localstout]

Love you vids

[@WritingFighter]

Kinda hoping and (kinda not) to see the engine(s) concepts I developed for my Sci-fi setting to be featured but so far haven't seen them. Though Spacedock seems keen to focus on realistic Sci-fi based on emerging, modern technology.

[@okonkwojones]

You missed the akimbo sawn off double barrel shotguns from Bungie’s 90s Mac classic Marathon 2. I remember the in-universe description from the manual, which was written in the voice of the self-aware AI Durandal, saying something like “I won’t bother explaining as your primative brain wouldn’t be able to grasp its operating mechanism” which is some pretty fun shade.

[@midnightexpress3604]

I KNEW MY IDEA ABOUT THE ENGINES CAUSING POSSIBLE DAMAGE TO THE SHEILDS WASN'T STUPID. I can full explain my Fleet tugs as possible things.

[@Corgblam]

Im very surprised you didnt mention Mechwarrior/Battletech, as fusion engines are prominently used in them. The mechs run on a hydrogen fusion reactor, heavily shielded from radiation and held in containment with a powerful magnetic field.

[@gabe9125]

This video is more focused on fusion thrust for spacecraft, not necessarily fusion reactors in general. Battletech uses fusion reactors in battlemechs, but doesn't go into depth much about how dropship and jumpship engines are actually powered. It's loosely suggested that dropships operate on some sort of ultra-efficient chemical thrusters to maintain thrust gravity, but it's never really delved into.

[@gabe9125]

BIG props for bringing up Battletech in general though, genuinely one of the most grounded and realistic sci-fi franchises out there, from the technologies to the people and politics

[@Corgblam]

@@gabe9125 It's a shame he never talks about the franchise at all. There's a lot of good stuff there.

[@anuvisraa5786]

@@gabe9125 it is explicitly say that drop ships aerospace fighters and warships use fusion drives

[@hurion1]

The "Real Engineering" channel here on youtube has a couple of really good videos on the current state of fusion technology from 5 months ago.

[@nekomakhea9440]

You don't need energy positive-fusion to generate thrust. You could have a fission reactor to make up the difference, and provide power to a fission drive that consumes net energy. In that case, use fusion as a way to get an engine with large mass flow (and thus large thrust) very hot exhaust (high fuel efficiency), while not actually needing a viable net-positive fusion power technology. Some form of nuclear propulsion (fusion, fission, or hybrid) is pretty much mandatory for non-fatal regular human interplanetary travel, especially for any planet further away than Mars. The energy involved also means gigantic heat radiators, unless you use something like metallic dust radiators or liquid tin radiators.

[@goiterlanternbase]

It seems no one approaches internal confinement fusion by focussing the outbound shockwave of the fusion into the next target. Im thinking of a reactor in the shape of a unilluminable room.

[@Sm00k]

i was like, where's Orion. I feel validaded. Suggestion, when you do Orion eventually, please, use Troy as an example.

[@dwainclark4557]

are you talking about "live free or die" by John Ringo? if so, yes please!

[@lawrencedoliveiro9104]

7:54 Ooh! Ooh! Project Orion!

[@KeithJanak]

Tell me more, i can't find anything on this game

[@danielefabbro822]

Well no, energy from fusion reaction can be used to produce electricity that will be the main mean to power up ion propulsors. Ion propulsors uses gas ionized to push a spaceship into space and its actually a sort of "tier 3" type of propulsion in a scale from 4 to 1 of types of space travel. We are currently at tier 4. With chemical propulsors that are not reliable to fly in space. At tier 2 we will have stuff like direct nuclear thrust or a ti-matter thrusters and warp etc. At tier 1 we will have hyperspace. Those techniques that will allows us to open a wormhole into space to travel from a point to another in exactly 0 seconds. Well, technically it will be "-1" but... Unfortunately we spend absolutely nothing on these technologies, so we expect to obtain such things just in two or maybe three centuries. 🤗 No less.

[@dvrchweesse1frfdozemkaanai594]

Can't wait for antimatter engines

[@MelvinGundlach]

I wasn’t prepared for the cosmic ray 😂

[@RiceWD05]

Seems most series forgo reaction mass or at least handwave it away. The only series I remember that uses it was the RCN series by David Drake which uses antimatter but only in vacuum for obvious reasons

[@stonesie81]

It's mentioned in passing on The Expanse a few times, from what I pieced together from watching the show they use water to cool the reactor, then split it into Hydrogen to produce thrust and Oxygen for the crew.. Also the thrusters are steam powered, not the most efficient but when you have a ready supply of superheated water it makes a lot of sense to use it. One character referred to manoeuvring on thrusters as "We're gonna Tea Kettle out of here"

[@RiceWD05]

@@stonesie81 haven't watched or read the Expanse so I really didn't know. Does make some sense

[@scifirealism5943]

Most scifi engines use reactionless drives.

[@fabiosilveira8571]

I did not expect to see Kurzgesagt here, but looking back? It only makes sense

[@NestorKYAT]

Spacedock/Kerbal crossover? Epic

[@veganmonter]

So the music credit is for Battlezone II but sounds like X4 Kingdom End

[@VAMobMember]

We have been working on Fusion power for decades so to everyone on the EXTREME LEFT of climate change and such I recommend you hold your breath till we have it as a power source for American daily life.

[@InternetzSpaceshipz]

What if you used the "Afterburner method" on a fissionable material like nuclear-salted water? Wouldn't use nearly as much of it as a standard nuclear-salt engine, and the fuel wouldn't need to be enriched so heavily with uranium or fissionable material, the heat and charged particles should be enough to induce fusion in the water molecules, the fissionable material still undergoes a chain reaction while remaining sub-critical and safe when stored, wouldn't need nearly as much neutron absorbing material around the fuel tanks, saving on containment weight.

[@agoddamnferret]

Would you be able to take this a step further and say "you have a fusion power plant cooling it and venting off the heated coolant is used to produce thrust and shunt heat off the reactor" (sure this adds complications but storywise it makes a good place to not have to hand wave off things like proper cooling and propellant, or is that not really going to count as a "fusion" drive in this context?

[@hoojiwana]

Using the heat of the reactor to expand propellant is basically a fusion drive, but kind of only the "afterburner" part. Perfectly doable but probably a bit of a waste of the potential of fusion! - hoojiwana from Spacedock

[@agoddamnferret]

@@hoojiwana I'm just thinking from a sci-fi where you don't have to magically handwave the other portions of the tech that aren't so feasible just yet regarding nuclear propulsion in general.

[@hoojiwana]

@@agoddamnferret Yeah its essential a fusion thermal rocket, just gotta balance the heat when the drive isn't actively running but the reactor is. - hoojiwana from Spacedock

[@agoddamnferret]

@@hoojiwana yeah was thinking about that too, using something like radiant cooling like the ISV from avatar or if you have a large coolant supply you've locally harvested etc you'd mix till thermal saturation while filling up power storage and then bring down your reactors once not moving. (heck even hybridization of this concept would possibly bring higher idle times. but yes that is an issue.

[@sixhundredandfive7123]

Cosmic Manta Rays.... brilliant.

[@noone-mz1cd]

Like the use of far future tech mod, basically the only “”””realistic”””” expression of fusion and nuclear fragment propulsion

[@ewanlee6337]

When you talk about efficiency, can you be specific if you mean mass efficiency or energy efficiency and it’s probably worth explaining how those efficiency are inversely proportional.

[@Pan_cak]

I have been waiting 😂😂😂 finally

[@Swooper86]

Question: Why is the magnetic containment field in a fusion reactor sometimes called a "magnetic bottle" (or just "bottle")?

[@hoojiwana]

It's a name for a layout of magnetic mirrors that traps charged particles between them. Sci-fi fusion seems to use it a bit more loosely as a sort of catch-all for magnetic confinement. - hoojiwana from Spacedock

[@CarlosAM1]

because that's how sci-fi likes to call it as it "bottles" the reaction, like igniting alcohol in a whoosh bottle. It's just the magnetic containment field to contain all the death and fury coming out the fusion reaction

[@janneaalto3956]

I guess antimatter-catalyzed fusion will be part of an episode on antimatter drives.

[@PulsefiredGaming]

wooooo lets goo fusion!

[@Bean-boi]

Ok but why so little thrust? If plasma pushes on the ship the same way gas propellent does, shouldn't it apply more force? Is it just a mass thing because inertia should be taken into account.

[@dying2play517]

At 9:12, WHAT THE HELL Engine is THAT!!! HOLY crap!

[@michaelgallup5041]

Is it possible to get a fast fusion engine running without any secondary propellant?

[@Adrenalin844]

Not really, no. You could fit massive ion engines to be powered by the energy of the reaction, but they'd still be absolutely pathetic compared to a fusion torch of any kind.

[@Mar7Coda6]

Please tell me you're doing a video on Starsector.

[@mr.ackermann807]

Now I will assume for the nif you knew about the lasers but not the whole system for it. I can appreciate the hype everyone has for the news, but its only true to an extent. In reality it is still far away from net energy gain and updated there lasers could get there but I dont think there budget will allow that anytime soon.

[@andromedach]

and then of course a certain novel where the unarmed human ship used its engine as a weapon

[@KrK-EST]

A bit out of date (3monts after video published) as Starship now has even. ore powerful V3 rocket engines and will continuesly get even stronger and better.

[@kamenwaticlients]

Next up Nuclear Pulse Rocketa, Nuclear Salt Water Rocket, VASMIR and othe nuke and plasma engines

[@Croz89]

Isn't that all fission based propulsion though?

[@kamenwaticlients]

@@Croz89 For the most part. I meant for a future episode.

[@scienceisthewaytogo8645]

~5:30 What about a combination of all the methods?

[@sockatume]

This feels a bit nitpicky but the “products have lower mass and the rest goes to energy” thing isn’t unique to fusion or to nuclear reactions in general, it’s just a necessary consequence of mass-energy equivalence in relativity. You get mass loss by the same mechanism when you rearrange atoms in to a lower-energy configuration in a chemical reaction, as you do when you rearrange nucleons in to a lower-energy configuration in a nuclear one. The magnitude of the change is just far smaller.