Plotholes You Noticed In Your Favorite Movies

[cerwillis]

But wouldn't it actually be like "planes in space"? Inertia applies whether you're in vacuum or atmosphere, so you would have to bank into turns or else risk breaking apart. If you were to slew the ship 90 degrees and continue along your previous trajectory while applying thrust in your new direction, you'd still be "banking", as the curve would (or should, anyway) be approximately the same as compared to a plane banking in atmosphere.

At least, that's what my gut says anyway. I don't have the math to back that up, though.

I'm referring to how the ships are built with "wings" and they yaw left and right in order to make turns, which wouldn't work without atmosphere. Additionally, the pilot is snug in their seat when the thrust is coming from behind them. In reality, your "down" would be towards the aft, and the ship would simply turn around to decelerate at 1g simulating gravity. In theory...

These pics sum up my thoughts:



VS

[Fivelives]

The fighters are capable of atmospheric flight, which explains their wings. The second one would be capable of atmospheric falling... but with style.

I'd assume that there are control jets on the underside and topside of the "planes in space" (just like there are on our now-unused space shuttles... that have wings!) and the rolling into turns would be habit from flying in atmosphere.

Also, it would help to diffuse the inertial stresses on the frame. If something is designed to fly in both an atmosphere and a vacuum, it would make sense to design the frame to handle stresses from atmospheric flight, since those would (naturally) be greater - or just impossible to work around. So technically, while you don't have to roll into a banking turn, it would be easier on the structure of your fighter than it would be to treat it like a ship that's incapable of atmospheric operating. They'd be designed to handle the stresses of atmospheric flight, which would mostly be a top to bottom support structure (to brace it against downforce caused by high- or inverse-G maneuvers), but they wouldn't be braced for side to side support, because you'd WANT them to be lightweight and nimble so you'd cut weight wherever you could without sacrificing durability or integrity.

Oh, and yaw is the horizontal relationship between nose and tail. Roll is the vertical relationship between wingtips (and pitch is the vertical relationship between nose and tail). People get that wrong a lot

[Treck]

Non aerodynamically shaped ships works fine in space, but if you wanna land with that ship, you would prefer if it wasnt shaped as a Borg cube.
And a lot of ships do land on planets in sci-fi.
The ships we use to reach space with today has wings, while the wings do nothing out in space, it helps getting out in orbit aswell as re-entry.

[Hrobertgar]

I'm ok with sleek looking ships that have a reasonable expectation of an atmospheric phase (Jedi do seem to fly their ships to a ground based port in the movies). Having large capital ships be all streamlined looks cool, but seems a bit less likely as atmospheric flight should not be requried of them.

I don't have an issue with the pilot, as he should be fully strapped in. I think most games tend to use flying/underwater motion as it gives a 3D 'feel' without putting too much strain on users.

I think full up space flight would involved orbital mechanics (as applicable) which would mess with most people, as well as exaggerated manuevering unless one assumes a massively robust reaction control system.

In space, if you are going 1000 mi/hr in one direction and want to turn around, its quickest to simply turn 180-deg then fire up the thrusters and decelerate. This really doesn't work for users. The airplane idea that you could 'fly' a circle is sort of ridiculous unless you have the monster control system. Keep in mind, while in the atmosphere a pilot generates turning power through large aerodynamic control surfaces known as wings, flaps, rudders, ailerons, etc. In space one has a main drive in the back and modest thrusters elsewhere. There is simply no possible way a real space ship would have enough manuevering thruster power to turn the ship in a loop against the power of the main drive.

Airplane control surfaces can generate several tons of force, which is simply not available in a spacecraft control system beyond the main drive, thus making most airplaney manuevers impossible in space.

[cerwillis]

I'd like to take this opp to mention that 2001 got a lot of this stuff right, when spaceflight was in it's infancy. The result was slow, silent and with a lot of little gas thrusters.

[Treck]

i think the whole point of that movie was to be as accurate as possible
Unlike every other show, who just tries to mix in a bit of science with the rest ^^

[Xenix]

The fighters are capable of atmospheric flight, which explains their wings. The second one would be capable of atmospheric falling... but with style.

I'd assume that there are control jets on the underside and topside of the "planes in space" (just like there are on our now-unused space shuttles... that have wings!) and the rolling into turns would be habit from flying in atmosphere.

Also, it would help to diffuse the inertial stresses on the frame. If something is designed to fly in both an atmosphere and a vacuum, it would make sense to design the frame to handle stresses from atmospheric flight, since those would (naturally) be greater - or just impossible to work around. So technically, while you don't have to roll into a banking turn, it would be easier on the structure of your fighter than it would be to treat it like a ship that's incapable of atmospheric operating. They'd be designed to handle the stresses of atmospheric flight, which would mostly be a top to bottom support structure (to brace it against downforce caused by high- or inverse-G maneuvers), but they wouldn't be braced for side to side support, because you'd WANT them to be lightweight and nimble so you'd cut weight wherever you could without sacrificing durability or integrity.

Oh, and yaw is the horizontal relationship between nose and tail. Roll is the vertical relationship between wingtips (and pitch is the vertical relationship between nose and tail). People get that wrong a lot

The reason you bank into a turn (in atmosphere) is because you need some force component pointing towards the center of the turn, and banking gives you a component of your lift in that direction without (much) affecting your other forces. You still need your thrust pointing in the same direction to counteract drag and you still need the majority of your lift to counteract gravity. (To do a coordinated turn, you need slightly more lift than when you're in steady level flight, so the vertical component of it is still the same as the force of gravity and you don't lose altitude)

In space, if you're going at some speed in one direction and want to do a similar, say 90°, turn, you'd similarly need a net force pointing towards the center of the turn. If your turning thrusters were pointed straight down, you'd have to completely turn the spacecraft on its side to do a coordinated turn like that - it'd be much simpler to either point your nose at the center of the turn and use your rear-facing thrusters, or have a sideways thruster. And, of course, you'd need to turn your spacecraft while you were thrusting to keep that pointed towards the center of the turn as you move.

A shallow banked turn in space, like you'd see an airplane do, is simply impractical - there's no sensible arrangement of thrusters that would make it a good idea. You'd either do a full 90° bank or none at all, and to do it fastest, you'd have to point your main thruster away from the center of the turn.

For an easy test if something's a "Planes in Space"-type system: if you turn your engines off and you slow down/stop, it's a planes-in-space type. In space, you shouldn't, since there's negligible drag, but that's very hard to deal with in a game/movie, since you could keep gaining speed as long as you have fuel (and what good movie/game has you deal with fuel in space combat, lol?). Realism would make combat about acceleration/velocity/distance, and not just velocity/distance and that's much harder to intuit.

[Arnock]

Newtonian space flight is one of the things that I really liked about babylon 5.


If one wants to try to think of a rational explanation to the 'planes in space' of most sci-fi movies, I tend to just think that the centripetal acceleration is provided by the same sci-fi magic technology that allows vertical takeoff and landing, and the banking turns are to angle that thrust outward, though, of course, it would have to be a full 90 degree bank for that to work...

[Fivelives]

I know why we bank into turns in atmosphere (and your explanation is only partially correct - but I'll avoid the "how planes fly" lecture for now :p ). I was offering an explanation for banking into turns in space.

Picture a thigh bone. That's a bone designed to accept stress in one direction - vertical. When you apply a horizontal force to it, it will shatter at a MUCH lower threshold than if you were to apply force vertically to it (a human femur can support weights in excess of 5,000 pounds, but it takes roughly a 1,200 pound force to the side to break it). That's what I was pointing out. Without banking into a turn the inertial forces applied to the relatively weaker side of your support struts in the frame of the plane would be MUCH greater.

[cerwillis]

I know why we bank into turns in atmosphere (and your explanation is only partially correct - but I'll avoid the "how planes fly" lecture for now :p ). I was offering an explanation for banking into turns in space.

Picture a thigh bone. That's a bone designed to accept stress in one direction - vertical. When you apply a horizontal force to it, it will shatter at a MUCH lower threshold than if you were to apply force vertically to it (a human femur can support weights in excess of 5,000 pounds, but it takes roughly a 1,200 pound force to the side to break it). That's what I was pointing out. Without banking into a turn the inertial forces applied to the relatively weaker side of your support struts in the frame of the plane would be MUCH greater.

How many Gs are really applied to a vehicle in micro-gravity and a vacuum? Any manned ship would have to keep life support in mind, and therefore would not be able to accelerate for any extended period of time at more than ~3Gs in any direction. Also, space travel theory generally states that you would accelerate for half of the trip and then decelerate the second half, so basically the same kps/s the whole time. A sudden turn could possibly pull 10-12Gs with flight suits, etc.

Ow, my brain hurts.

[Amirya]

I'm sorry I mentioned Star Trek now.

[Xenix]

I know why we bank into turns in atmosphere (and your explanation is only partially correct - but I'll avoid the "how planes fly" lecture for now :p ). I was offering an explanation for banking into turns in space.

Picture a thigh bone. That's a bone designed to accept stress in one direction - vertical. When you apply a horizontal force to it, it will shatter at a MUCH lower threshold than if you were to apply force vertically to it (a human femur can support weights in excess of 5,000 pounds, but it takes roughly a 1,200 pound force to the side to break it). That's what I was pointing out. Without banking into a turn the inertial forces applied to the relatively weaker side of your support struts in the frame of the plane would be MUCH greater.

Heh - it's as correct as you can be while avoiding the couple of hours of Flight Dynamics lecture about everything involved in a coordinated level turn - you need a centripetal force, you get it from your lift vector, you do stuff to make sure everything else stays peachy while your lift vector isn't vertical.

As for aircraft, keep in mind that wing structures are designed to handle mainly bending loads, not vertical loads that go straight from top to bottom. This means the highest stress will be in the axial (along the wingspan) direction, not the vertical direction. In your thighbone example, you'd be comparing the force it takes to compress it axially versus the force it takes to snap it if you bent it.

If you're getting into whether the aircraft body structure can handle more load from the front/side/top, then that depends on the exact craft involved, and the distribution of thrusters providing the load while in space. You could design it however you want, and how current airplanes are designed (to handle most of the airloads coming through the wings) would have nothing to do with it when you could place the source of your acceleration wherever you want.

Edit: @Cerwillis

Really, none of this conversation matters in the slightest in a sci-fi universe. Just invoke the magic of "inertial compensators" and you can pull however many g's your compensator can handle even if your ship is made out of toothpicks.

[Fivelives]

Heh - it's as correct as you can be while avoiding the couple of hours of Flight Dynamics lecture about everything involved in a coordinated level turn

Or, be a licensed pilot. Which I kinda am. :p

If you're getting into whether the aircraft body structure can handle more load from the front/side/top

That's what I'm getting at, yeah. Wings wouldn't have as big an issue as the fuselage and tail assembly would have with high-speed high-G maneuvers.

how current airplanes are designed (to handle most of the airloads coming through the wings)

Mmm. Actually, most of the stress on a plane's fuselage comes from the tail assembly - torsion from the fin and rudder, and bending from the lift produced by the tail - rather than from the wings. You get compression when you bank into a turn.

But yeah, I pretty much think you can handwave it all with "inertial compensators". You're already swallowing artificial gravity, after all.

[cerwillis]

IMO space travel is impossible while limited to our meatbag bodies. I believe that interstellar space travel will exist when we can trancend our bodies into some kind of mechanical or digital consciousnesses and no longer be limited by time or other mortal issues.

[Dorvan]

I can buy into Star Trek physics without thinking to hard about it and enjoy it....as long as they're reasonably consistent about it, anyway. I've been watching a fair bit of ST series since they popped up on Netflix. I did, however, have a /facepalm moment in the second episode of Voyager, which featured both a terrible definition/explanation of an event horizon, and referred to "warp particles", a concept which had never been mentioned before and which (thankfully) never made an appearance again in any sort of Star Trek episode.

Of course, Voyager was always the "let's try to be hip and current" Star Trek, so I'm expecting the science and technobabble to remain pretty terrible as I watch more.