Reaction Engines in Space Opera

Continuing on in essays about Science Fiction, Momus News wonders: Do reaction engines have a place in Space Opera?

Art by: Steve Bidmead from Pixabay

Short answer: No.

Reaction Engines

What are reaction engines? According to Newton’s Third Law, “For every action, there is an equal and opposite reaction.” A jet or rocket engine propels its craft by ejecting material (often plasma) out the back end at high velocity. This “Action” forces the craft to move in the other direction (forward) as a result of Newton’s Third Law. Take a 777 flight from JFK to Heathrow and you’ve experienced how a jet or even a spacecraft operates.

This is precisely what a reaction engine is. It “reacts” to the “action” of expelling material out of the nozzle in the back. Thing is, to do this, you need boatloads of fuel. In jet aircraft, small planes have a shorter range. Why? They have less space to put all that fuel. Bigger plane means more fuel space, more fuel space, means longer range.

Fate of the Galaxy

Space Opera is all about Big Stuff, the fate of the galaxy and all that. Well, let’s consider how big the galaxy is. It is roughly, 100,000 light years across.. Just to get to the closest star to us (Proxima Centauri), according to using reaction engines, it would take “…at a maximum velocity of 56,000 km/h, Deep Space 1 would take over 81,000 years to traverse the 4.24 light years between Earth and Proxima Centauri. To put that time-scale into perspective, that would be over 2,700 human generations.”

That’s just getting to the closest star. Now, it could take less time if the starship propelled itself at one gee acceleration until halfway there then decelerated to arrive at zero velocity at the star. IIRC that would be twenty-four years.

Still too freakin’ long, and way too long for anybody to influence the fate of the galaxy.

So do reaction engines like the giant engines we see in the Star Wars Star Destroyer make any sense at all?

Star Wars Star Destroyer

Nope. Those engines are only useful between hyper jumps, and they constitute most of the mass of a star destroyer. So, I want to ask, “Where’s all the damned fuel for those ginormous engines?” That requires a whole lot more space. That would leave about enough room for a life boat aboard the ship! Now before you get all pissy about me stepping on Star Wars, I still love the movies. It’s a fun story if not scientifically logical. Who cares? I enjoy it anyway.

A Science Fiction Tradeoff

In my book, “The Huralon incident” I try to manage a tradeoff between a great adventure story and scientifically plausible drive systems. For that reason, there are no gigantic reaction engines in my book. Instead, I use a drive system straight from my own imagination that uses the current scientific theory of dark matter/dark energy. These are ideas posited by scientists to explain the observable phenomenon of stars accelerating from each other and stars that fail to spin away from galaxies when they should. From that I suggest, “what if dark matter/dark energy were a medium, much like the sea that mariners sailed across in windjammers, that futuristic sailors might use to propel their ships? The dark paddles.”

Proof this whole article is merely a vehicle for a shameless self-promotion.

How does this work, exactly? Well I’m happy to explain, but you gotta buy the book to see how I did that. A cheesy effort to make you buy the book? Well, yeah, but I think you’ll appreciate my genius. That’s my own “humble” opinion, of course.

About EagleAye

I like looking at the serious subjects in the news and seeking the lighter side of the issue. I love satire and spoofs. I see the ridiculous side of things all the time, and my goal is to share that light-hearted view.
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7 Responses to Reaction Engines in Space Opera

  1. I think what you’ve created is genius – brilliant concept and a great book! Well done you, and no shame at all in promoting it! Apropos the Star Destroyer and its giant rocket exhausts with nonexistent fuel tankage – yeah, I wondered about that too. Maybe they are built around the Star Wars equivalent of ‘hammerspace’ with the necessary 400 gigatons of whatever those motors use (cesium, maybe?). I suspect the actual explanation, of course, is that Colin Cantwell or maybe somebody else at ILM decided that ‘hey, these would look cool if I glued them on here, after I put those WW2 tank parts on the bridgework’, but I’m a spoil-sport like that… 🙂

    Liked by 1 person

    • EagleAye says:

      Haha! It does look like tank parts glued on. Probably is. Never heard of Hammerspace, though I presume its some sort of extradimensional space, a pocket universe of some such. If they at least claimed that I’d feel better. Glad you liked the drive system concept. I wonder if it will catch on. I’m still learning how to market and get the word out there. Then it would be interesting to see what scifi fans think of it. Thanks so much!

      Liked by 1 person

      • As far as I know, the Star Wars models indeed used tank parts and other stuff from commercial kits to add detail – apart from Panzer IV’s etc the Hasegawa 1/72 ‘Leopold’ railway gun was a favourite. (Bits from it also appear, evidently, on Cylon raiders from the 1970s series). There’s a bit of detail about the process here: – hilarious, when you think about it, that these days the CGI artists have to carefully reproduce what, at the time, were expedients… Reputedly the idea was concocted in the 1960s by Gerry Anderson’s SFX guys in London who needed cheap(ish) ways of making their sci-fi props, and there just happened to be a model shop across the road from the studio.

        Liked by 1 person

  2. Joy Pixley says:

    This is a great way of separating people who insist on “hard” science fiction and (to me) seem to care mostly about whether the science is right and are willing to read stupid plots and one-dimensional characters and those who don’t mind if the science part is a bit hand-wavy as long as the characters are engaging and the plot is compelling. It’s a spectrum, clearly, and I like a good “what if” discussion like the one you have here. But like you say, come on, it’s still a fun story!

    Liked by 1 person

    • EagleAye says:

      Very true. I don’t mind handwavium, but like we discussed before, it has to have rules. There can’t be all plusses and no minuses. That’s no fun at all. Even if you make stuff up it makes for an interesting plot if there’s problems, like if you’ve got a gun that can do anything, but you can’t ever let it get wet or it goes supernova, for instance. Yikes! I just like it if the writer cares enough to make up a technical explanation for how this super-thingee works, rather than shine it on completely and leaving us hanging. That’s like producing the solution out of thin air at the last moment of the book, with no hint of it at any time prior. That’s just lazy writing. I posted an excerpt of this article on a Facebook group, and one guy accused me of “nerding-out too much.” I just had to laugh, because he’s right. Still, though people may, and rightly so, demand well-rounded and interesting characters, I think it’s also fair for me to demand a “sciency feel” even if not real science, in my science fiction. While writing The Huralon Incident, I spent a lot of time getting beta-reads from soft-science fiction writers to, hopefully, ensure the characters are as well-filled out as the technology. Crossing my fingers.

      Liked by 1 person

      • Joy Pixley says:

        In my opinion, you are “science-ing out” just the right amount! I totally agree, of course: you really need clear rules and clear limitations, whether it’s futuristic science or magic, if you’re going to have the characters use that science or magic to solve their problems. Otherwise it feels like they could just do anything they happen to need to do to get out of a jam: very deus ex machina, ugh.

        Liked by 1 person

  3. List of X says:

    I don’t think the days of reaction mass are nearly over. The basic idea of the reaction mass is to convert mass to kinetic energy (which heat is a form of), and jet fuel is very inefficient when it comes to the mass to energy conversion. If my math is right, a pound of plutonium can produce around the same amount of energy as about 2.5 million pounds of jet fuel, and a pound of mass converted to pure energy (the E=mc2 formula) will produce about a 1000 times as much as a pound of plutonium. The question is how to use that mass (matter or nuclear fuel) for propulsion, but once it’s solved, it would solve the current problem of having to carry about 10 pounds of rocket fuel for a pound of actual rocket just to make a one way trip to space.


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