This question popped into my head when I was watching a preview for the new Star Wars movie. While I realize that science fiction is just that, it seems that even with all the twisting and turning the pilots do in those starfighters, the change in acceleration doesn’t seem to bug them too much. (By the way, I haven’t watched any Star Wars movie in years. I might be forgetting if they get jostled around or not, if their suits or cockpits are pressurized/have false gravity, etc.) I’m in a very basic physics course right now, and I know that g is a unit of acceleration equal to the acceleration due to Earth’s gravity, but we’ve only discussed g’s when you’re on the Earth’s surface. How much does outer space make a difference in experiencing g’s, if at all? Thanks.
If your spaceship is in orbit (i.e. in free-fall), the occupants would not experience any gravitational acceleration. That’s why they float around inside.
If your spaceship had a big engine capable of accelreating the spaceship at 9.8m/s/s (i.e. every second it gains 9.8 m/s = 22 mph of speed), the occupants would feel one G of acceleration. You can stand on the “floor” (rear wall) of the spaceship and walk around just as you would on the earth. If your spaceship can do 3 G, you probably need to be strapped to a seat, and you will be pressed against the seat at three times what you weigh on earth.
I’m not sure if that answers the question, but feel free to keep asking…
Being in space makes no difference at all. The Star wars dudes all use antigravity devices to keep the force at bay.
To answer your last question, none what-so-ever. Acceleration is acceleration and it doesn’t matter whether it happens in a gravitaional field or not. If your craft changes its direction of travel or speed, your body will feel a force on it as it resists that change.
Oh, and the way spacecraft, especially fighters, moved in Star Wars was highly unrealistic. The movie was space-opera, after all, not a documentary. Much closer to the way things work in space are the Starfuries in Babylon 5. Several times over the years I noticed they would use tactics like rotate in place and blast at somone next to or even behind them while continuing on the original vector.
(On preview: Drat. Too slow. Well, I’m posting anyway.)
DD
Yes, what was just said. When you whip around at high speeds (or low speeds) in your spacecraft and change directions the force you are feeling is G’s. Very simple explaination . . .no more
The basic concept is that acceleration is acceleration, whether it’s from gravitational attraction or from a rocket engine. Any change in a ship’s velocity (which is both speed and direction) requires acceleration, which is felt by the occupant of the ship as a push in the opposite direction.
A “g” is obviously an Earth-centric unit of measurement, but no more so than feet, meters or seconds. Even long, long ago in a galaxy far, far away we can assume that acceleration is imposed on the pilot (in whatever units). Of course space combat that’s true to physics probably wouldn’t be that interesting cinematically, so most SF uses techological hand waving (grav generators, inertial dampers, or just ignoring it completely) to make space combat look like a WWII airial dogfight.
Yes. And this is why spacecraft **will **likely bank when turning, like aircraft. Taking the radial acceleration loads through the seat in a consistant direction will be much easier on our space pilot’s stomach contents than taking them in random directions. Of course once he had finished the turn there would be no reason for him to “level out” (meaningless in space) again…he wouldn’t need to roll untill he wished to make a turn in a diffent direction.
If hollywood ever “got” this, It would be as cool to watch as the WW-I dogfight paradigm they currently use.
Not to be a SW dork, but the Star Wars ships use some form of anti-gravity as well as rockets to move. It’s not inconceiveable that the fighters tend to be always pointed forward in the direction of the main thrusters and use wide sweeping turns like a terrestrial fighter plane instead of the rotate and thrust style of Babylon 5 (or Asteroids).
Doubtful Kevbo. I can think of only one science fiction movie that even attempted to portray space physics correctly, 2001: A Space Odyssey. The dogfighting airplane mold has been used because it serves as a frame of reference people understand. It might be a novelty to see correct physics but what is the point of noting that there is no universal “up” when all the other laws of physics have to be violated to accomplish violent maneuvers in the first place. 2001 is one of my all time favorite movies but I have much more fun watching TIE fighters and X-wings mix it up.
Intertial dampers and artificial gravity keep physics forces at bay but nothing stops the force. 
Cockatiel, science fiction takes suspension of disbelief, something that can easily be damaged by hitting a plot hole toof fast. Since spaceships can’t exert forces aginst the ground as cars can or agsint the air the way a plane can they must rely on engine thrust to turn. Since I have never seen a SciFi space ship with engines configured to do that I must assume they operate on FM theory.
FM = ****in’ Magic
On a side note my high school physics instructor once asked us if there was any experiment one could do to tell if he was in a closed room sitting on the earth or in an elevator in space being accelerated in the direction of the ceiling at 9.8m/s[sup]2[/sup]. I suppose a toy gyroscope could be used to measure precession of the earth. Don’t think you could fool that in the space elevator. If you stipulate the plant is not rotating or revolving then one could measure gravity at the top and bottom of the elevator car. The difference on earth would be miniscule but since this is a thought experiment it would be able to determine where you are.
Wait… how did they manage that without violating the conservation of angular momentum? Even if you fire a thruster out of line with the center of mass it would cause a change in the momentum of the center of mass as well as changing the angular momentum.
If you can measure the direction of a plumb line accurately enough you can show that it doesn’t point in the same direction at opposite sides of the room. Then again, you have to somehow justify being able to compare “directions” from two different points of space…
I think the Starfury had 8 thrusters, two on each “wing” pointing forward and back. They spin around by firing forward thrustsers on one side and backward thrusters on the opposite side.
Nevertheless, the Starfuries still exhibited some aircraft-like motion. When they turned, they would usually do so with the nose always pointing “forward” (direction of motion), which means they were using side-firing thrusters - which we never saw.
Anyway angular momentum is only conserved for a closed system, and a spaceship firing its thrusters is not a closed system. (Unless you look at the exhaust gas as part of the system.)
Notice I said “even if”, noting that firing a thruster would be a possible answer…
Honestly, I’m not the idiot everybody says I am.
Sorry, I usually try to err on the side of dumbing things too much, if only for the benefit of others who may be reading. Nothing personal.
BTW it’s also possible to spin a spacecraft using momentum wheels. Spin up the momentum wheel (basically a flywheel), and the rest of the ship spins the other way.
No one wants to watch a movie of what real space combat would be like. Sit in your fighter, watch your display, engage your weapons system, haul ass in a random direction, and wait to see if you die, or the guy you cannot see with your naked eye dies. Repeat.
You don’t want to broadcast to your mother ship, and you darned sure don’t want the mother ship broadcasting to you. You meet where you agreed to meet, and if anyone shows up, your side won.
I’m not going to watch that movie, even though it is much more likely to reflect actual possible future fact. Add into it the fact that even with light speed, or speeds in the ten to a hundred times light speed, these individual battles would take weeks or months, and the war centuries. Boring.
Tris
“For to win one hundred victories in one hundred battles is not the acme of skill. To subdue the enemy without fighting is the acme of skill.” ~ Sun-tzu ~
A long time ago, in a thread far, far away, right here on the Dope, I did a back-of-the-envelope kind of estimate of the gees Luke’s X-wing must be pulling to make some of the maneuvers he made flying around over the Death Star. I figured at best every capillary in his face would have burst, and his eyes would be filled with blood. At worst, they’d be picking his remains out of narrow spaces in the cockpit with a toothpick. Anyhoo, everyone told me I was full of shit, underestimated turning radii, not accounting properly for camera tracking, and neglecting relative motion of ships during dogfights that might have made some motion seem more drastic than it was.
I still think some of those turns looked pretty punishing, though.
You can try it out, if you like. I did.
And you know what? You’re right! It’s boring as shit. Realistic physics in space is maddening. I find myself flying around like a drunk guy on a snowmobile in the middle of a glassy-smooth frozen lake with a big oil slick on the surface. I spend all my time overshooting the target, and then struggling mightily to get a proper vector again. Adding lateral thrusters that stabilize the craft burns through fuel so quickly I’m uncommanded floating debris in minutes. Give me an atomosphere, or give me death.
That would only be true if Luke was doing lots of pushovers and other negative-G maneuvers which pull him up from the seat against his torso harness. In any event it doesn’t take any extraordinary negagive G load to do that. People using those gravity boots to hang upside down experience burst capillaries in their eyes with no more than -1G on their bodies. Normal ACM strives for positive G loading which means there is less blood in his head causing blackouts. Of course Luke’s legs and feet are another matter.
That’s another excellent way. Not difficult to measure. Just use your vernier tape measure to get the distance from the hanging points of each plumb line and between the tips of the bobs. If you had the stipulateion that opposite walls of the box were parallel you woudn’t even need to do that.
A piffle. Just place two thrusters on opposite sides and equal distances from the center of mass in opposite directions. Rotation without change in momentum. In any event it takes far less force to rotate than to change the momentum vector so even if you didn’t take such measures it may not affect direction of travel enough to worry about.
Well, that also runs into the problem I mentioned about having to justify being able to call two lines in different places “parallel”.
Yes, that thruster configuration would work. Most of the space opera I see (and most of “science fiction” series these days are space opera) don’t use such a configuration, though. I’m not familiar with the series in question, so I admit I assumed the standard rear thruster positioning.
As for the force required, it really depends on where the thruster is placed and how the mass of the ship is distributed (moment of inertia). That’s as maybe, though, since it was stated the ships maintained the same vector, not almost the same vector.
I felt pretty sure they did. I remember scenes where an X-Wing, with no change in attitude or forward velocity (that I can discern, anyway), drops like a rock to avoid a TIE fighter or re-enter the trench. My Luke-toothpaste comments are more about some of those U-turns.