We’re all nerds here, we’ve all smirked and snarked about bad movie physics… you know this song by heart. “There’s no sound in space.” “Gas tanks don’t explode when you shoot them.” “Why would a spaceship need to bank-to-turn?” Hang on, back up. Let’s talk about that last one for a second. Maybe there’s a good reason for a spaceship to bank-to-turn.
If you’re reading this, then you’re probably a Star Wars fan or at least have friends or family who are. So you may already know why, from a filmmaking standpoint, spaceships always seem to bank-to-turn. The very short answer is, because it looks cool. The mostly short answer is, because that’s what they did in Star Wars, and the film industry has spent the last 43 years trying to recapture force-lightning in a bottle, occasionally even succeeding (looking at you, Avengers). The longer answer is that George Lucas made his first rough-cut of the original Star Wars before any special effects were done by cutting up and splicing together old World War 2 fighter plane dogfight footage, and then ILM (Industrial Light and Magic – Ole George’s special effects company) more or less copied what they saw with X-wing and TIE fighter models. So, at least in Star Wars, spaceships fly like airplanes because they basically were airplanes.
OK, film history lesson over, that’s not what I mean when I say there’s a good reason for spaceships to bank-to-turn. Let’s talk “in-universe” explanations. Luke Skywalker doesn’t know George Lucas or ILM, and he’s never heard of World War 2, or seen a P-51 mustang, so why, a long time ago, in a galaxy far far away, does he fly his X-wing like a 1940’s prop plane? Well, let’s look at this like the designers at the Incom straighter manufacturing corporation would have looked at it. What does an X-wing need to do? First, it needs to hold a pilot, and that pilot needs to stay alive, conscious, and alert while performing his duties as a starfighter. Next, It needs to evade enemy fire, and fire upon enemy ships, which means it needs to pull some pretty significant maneuvers. Finally, it needs to take off and land and traverse an atmosphere before and after it’s done its starfighter duty. There’s probably a whole lot more to the SRD (system requirements document) for the Incom T-65B (that’s the classic X-wing), but these are the three that are relevant to this discussion.
Let’s start with the second one first. These things can really move. They fly fast and they turn hard. They have to because TIE fighters fly just as fast and turn just as hard. Also, lest we forget, they’re firing lasers at each other, not bullets, so if you’re in the crosshairs when your opponent pulls the trigger, that’s it, you ain’t maneuvering out of the way, fly boy.
Any time you change speeds or directions, you’re accelerating, or “pulling g’s” which we experience as a force acting uniformly on our entire body and everything inside it, including squishy things like organs, and your blood which will pool in the opposite direction of your acceleration.
Getting back to the first requirement above, because humans (I’m assuming this applies to humans and humanoids in Star Wars as well) evolved on a planet where gravity is more or less always pulling us in the same direction, we tend to handle g’s best in that direction. A human can handle around 5 positive g’s (downward), but only about 2-3 negative (upward) without blacking out. Additionally, we do better when we have something cushioning us, like the seat bottom and back. Mythbusters showed that rear-facing airplane seats provide much more protection than forward-facing seats in a crash (where the g’s are forcing everything forward as the plane comes to a sudden stop), which is also why the AAP recommends rear-facing car seats for young children in the event of crashes. Similarly, with nothing to keep You from flying sideways except a harness or seat belt, side impacts tend to result in much more catastrophic injuries at lower speeds than rear-end or head-on collisions. So essentially, the designers would want to limit the accelerations as much as possible to be pushing the pilots down and back into their seats. Since traffic collisions aren’t a concern in a spaceship, the accelerations we’re mostly talking about are speeding up, and turning. So, the idea that a starfighter would maneuver the way a satellite does using thrusters pointing in all directions to change directions without turning, doesn’t make sense, you want the pilot to always be experiencing positive g’s back and downward.
So we’re left with more-or-less two options, for making a turn, the X-wing can swing around to whatever direction the pilot needs to turn, and then execute a forward burn to change directions (this is called skid-to-turn), or it can use vectored thrust and bank-to-turn like an airplane. Both of these have pros and cons, the human body can take more g’s perpendicular to the spine than parallel to it, so using a skid-to-turn scheme (this is what is employed in The Expanse and often lauded as an example of the realistic physics in that show), where you turn the ship and then fire the engines to change directions would allow you to pull more g’s survivably, however, this could be disorienting for the pilot and slower to execute because the maneuver requires multiple steps to execute. Since a bank-to-turn system puts more of the g-load on the pilots parallel to their spines, they won’t be able to pull as many g’s, but they’ll be facing forward the whole time, and the maneuver happens all in one motion. Also of note, a banking turn in the vacuum of space won’t look exactly like a banking turn in the atmosphere because the ship won’t be able to use any aerodynamic control surfaces to execute it’s turn; it would have to use thrust vectoring. But this is not unheard of even in modern aviation aircraft. F-15 fighters use thrust vectoring to execute sharper turns than they would be able to achieve using aerodynamics alone. So, what to do if you’re an Incom Corporation engineer getting ready to pitch your design to your Hutt boss who might just throw you to the Rancor if he doesn’t like your idea? How do you choose?
Well, we haven’t talked about that third requirement yet. Remember that X-wings (and other starfighters and freighters in Star Wars) don’t just fly in space, they have to take off and land from planet surfaces often, and we even see them dogfighting in the atmosphere in The Force Awakens.
So, the X-wing is going to have to include bank-to-turn capability anyway to fly in the atmosphere no matter what it does once it is in the vacuum of space. So do you think the profit conscious Incom Corporation (this is Star Wars, not Trek, cost and profit matter, big time) is going to go for the added weight and cost of two complete separate guidance and control systems for endo- and exo-atmospheric maneuvering just to eek out a few more g’s of maneuverability? I’m thinking no. X-wings bank to turn, and I’m here to tell you, that makes perfect sense in the context of the Star Wars galaxy.
In my research for this article, i came across this gem on Wookieepedia:
It’s a scan of an ILM cheat sheet from the Return of the Jedi production showing the different speeds and maneuverability of the various starfighters involved in the Battle of Endor. There are (at least) three major takeaways from this chart. First, I love that ILM had this, it warms my heart to know that they went to this level of detail planning the dogfights. Second, that unit of speed, MGLT, is a total mystery. Consensus seems to be that it stands for megalight per hour, there doesn’t seem to be any official or widely accepted unofficial definition of what that actually is. It’s definitely not faster than the speed of light, because in other official sources, this is listed as the “sub-light” or “realspace” speed, and there is a different measurement for hyperspace travel. IF it means 1 millionth the speed of light, which is something i’ve seen tossed out by other geeks around the web trying to make sense of the physics of Star Wars, that’s still 30 km/s or about 67,000 mph, which is insanely fast, and you’d never be able to pull any kind of maneuver of that those speeds and survive, your turning radius would be, like, the Earth. So i’m not sure what an MGLT is, but ultimately, it doesn’t matter because it’s mostly being used as a comparative statistic anyway (e.g. an A-wing is twice as fast as a B-wing). Finally, Look at the bottom of that chart, The Millenium Falcon is decidedly not “the fastest ship in the fleet” Han, you lying sack of bantha poodoo.