Fatal Flaws in Sci-Fi Films: which ones drive you mad? I'll start it off...

[Gigatron]

You're still not seeing the "equal and opposite" part of the equation. Yes if you expel two pounds of O2 out of a spaceship it will push the space ship forwards but it won't move the same distance as the O2 does unless the spaceship also weighs two pounds.

In space, the spaceship weighs 0 pounds. So two pounds of force from the O2 burst should be more than enough to move the multi-ton ship.

In real life, the space shuttle is docked using tiny thrusters for fine movements. Watch Apollo 13, they course-correct using short bursts of propellant.

-Fred

 

[fuelish]

In space, the spaceship weighs 0 pounds. So two pounds of force from the O2 burst should be more than enough to move the multi-ton ship.

In real life, the space shuttle is docked using tiny thrusters for fine movements. Watch Apollo 13, they course-correct using short bursts of propellant.

-Fred

Take a large girder hanging from a chain. It is very easy to get it spinning by pushing gently against it but trying to stop it abruptly can get you hurt because of inertia and its great mass.

Same thing with a huge ship in a vacuum. A gentle push can get it moving(slowly), changing that movement (abruptly) requires a large input.
Newtons third law and first law at work.

 

[JediG60racer]

In Road Warrior*, the interceptor has no intake air filtration. A roots style blower would last maybe a hundred hours in those dirty conditions(Based on how filthy the car is) The motor would be toast as well, but it would last longer than the blower.

*One of my faves.

It had a bug-catcher butterfly plate air filter housing. The K+N filter resides in the collector neck before it dumps air into the actual intake of the blower. I had one on my Pontiac 400ci motor with a Weiand blower.

 

[Kerr Avon]

Is that still applicable in a vacuum? With no gravity, resistance or friction to overcome, the slightest nudge should be enough to knock it off course.

In a conventional airplane, you adjust the angle of the vertical stabilizer/rudder to turn the plane. The rudder is now acting as a deflector, turning the nose of the craft in the direction of the rudder angle.

Boats turn by pushing against the water in the same way. And on a car, is the friction between the road and the tire.

In all these cases, it's a matter of A pushing against B, so you need more force to move heavier objects.

In space, you're relying on newton's first law - for every action, there is an opposite and equal reaction. You use a thruster to expel air in the opposite direction you wish to travel. Without an opposing force to overcome (gravity, friction or resistance), the slightest poof of air should be enough to move you. Unless there's something I'm not seeing.

-Fred

Yes, you're missing inertia. Inertia is the resistance of something to change it's speed and direction. An object that is 'not moving' still has inertia that needs to be overcome. The Space Shuttle won't move just because someone opens the payload door and let's a fart rip from last night's beans.

BTW, mentioning something is 'not moving' is really just using a frame of reference. Everything in the universe is in constant motion, it just depends on your frame of reference.

 

[Kerr Avon]

In space, the spaceship weighs 0 pounds. So two pounds of force from the O2 burst should be more than enough to move the multi-ton ship.

In real life, the space shuttle is docked using tiny thrusters for fine movements. Watch Apollo 13, they course-correct using short bursts of propellant.

-Fred

Those tiny jets expell a ****load of power. They aren't just aerosol cans used for thrust.

 

[Gigatron]

Yes, you're missing inertia. Inertia is the resistance of something to change it's speed and direction. An object that is 'not moving' still has inertia that needs to be overcome. The Space Shuttle won't move just because someone opens the payload door and let's a fart rip from last night's beans.

But isn't the full definition of inertia "the resistance of a body to to move or change direction unless acted upon by an outside force"? Wouldn't the fart be an outside force?

Those tiny jets expell a ****load of power. They aren't just aerosol cans used for thrust.

I never said they weren't powerful. I'm just saying that in space, a ship the size of a star destroyer should be as maneuverable as a TIE fighter. If you loaded up a Destroyer with millions of maneuvering jets (which should be on all ships in outerspace), it should be able to keep pace with a smaller fighter with a proportional number of thrusters.

Let's say you're piloting your Y-wing - an aerodynamic monstrosity. You fire your engines and that launches you in a straight-line trajectory. Since there's no air movement over any discernable surfaces, how do you turn without directional thrusters? You can't - but the movie shows them doing loops and hard banks.


What I'm trying to grasp is why it takes anything more than a can of hairspray to maneuver any ship, regardless of size. What's keeping that ship from instantaneous direction change? There's no friction and no gravity, so there's nothing pushing against it and nothing pulling it towards it.

This is going to be one of those science things that give me a looping headache. Like if everything in the universe is moving away from each other (exapnding) - what the hell is it expanding into. Expansion and contraction propose that there is an outer edge. Like if I blow up a balloon. It will either expand until it hits the edges of the room, or it explodes. Is the same thing happening to the universe :wacko?

-Fred

 

[fuelish]

Try reading this: http://en.wikipedia.org/wiki/Inertia

There is some stuff part way down about gravitational v/s inertial mass that might help you wrap your head around it.

 

[Kerr Avon]

But isn't the full definition of inertia "the resistance of a body to to move or change direction unless acted upon by an outside force"? Wouldn't the fart be an outside force?

Yes, the fart would be an outside force that would impact the inertia of the shuttle, but not nearly enough to result in some kind of change in velocity. I can't explain it in great enough detail to probably sufficiently educate you on the subject, but I can assure you that a Star Destroyer would not be able to navigate with the same kind of nimbleness that a TIE Fighter could if it's using any drive system that follows Newtonian physics.

I won't even get into the whole hyperspace thing.

 

[Nwerke]

I never said they weren't powerful. I'm just saying that in space, a ship the size of a star destroyer should be as maneuverable as a TIE fighter.

:confused How could it be? It has many orders of magnitude more mass and ditto inertia. To change direction, it has to exert vastly more energy than the TIE. You're still not getting the difference between mass and weight. Gravity acts on mass to give it weight. Without weight, the mass doesn't go away. Mass is what grants inertia, not weight.

If you loaded up a Destroyer with millions of maneuvering jets (which should be on all ships in outerspace), it should be able to keep pace with a smaller fighter with a proportional number of thrusters.

As I say, it comes down to expenditure of energy. If you want your ISD to be as manouverable as your TIE, you can do that but will have to expend a LOT more energy. So yeah, you'd have to load it up with jets, aetheric rudders or whatever the EU BS is these days. Does the ship even have enough reaction mass storage volume to power them all to the degree required? Maybe not.

Let's say you're piloting your Y-wing - an aerodynamic monstrosity. You fire your engines and that launches you in a straight-line trajectory. Since there's no air movement over any discernable surfaces, how do you turn without directional thrusters? You can't - but the movie shows them doing loops and hard banks.

The Y-wing has what are meant to be thrust-vectoring vanes so you could always claim the ship really is vectoring it's engine thrust: this is like a built-in, self-generated atmosphere and rudder combination. The reality is of course that they are too far from the engine nozzles to be very effective and would only work under acceleration anyway - and the fact that no other ship in the SW universe has anything really similar is a good sign that they generally use something else anyway.

What I'm trying to grasp is why it takes anything more than a can of hairspray to maneuver any ship, regardless of size. What's keeping that ship from instantaneous direction change? There's no friction and no gravity, so there's nothing pushing against it and nothing pulling it towards it.

Mass and inertia. They exist independent of gravity and atmosphere.

This is going to be one of those science things that give me a looping headache. Like if everything in the universe is moving away from each other (exapnding) - what the hell is it expanding into. Expansion and contraction propose that there is an outer edge. Like if I blow up a balloon. It will either expand until it hits the edges of the room, or it explodes. Is the same thing happening to the universe :wacko?
-Fred

In the case of the universe, there is no "room". I think the quote is "Space is finite, but unbounded".

Just briefly back to the manouevre question. Ships in SW have inertial compensators and artificial gravity. If they can manipulate gravity and inertia, why not just invoke the same technology for directional control? That would allow for all the manouevres we see on screen and a lot more besides. Reactor output would be the limiting factor for manouvres, rather than reaction mass storage volume.

I guess the EU writers just never thought of it?

 

[Solo4114]

The Y-wing has what are meant to be thrust-vectoring vanes so you could always claim the ship really is vectoring it's engine thrust: this is like a built-in, self-generated atmosphere and rudder combination. The reality is of course that they are too far from the engine nozzles to be very effective and would only work under acceleration anyway - and the fact that no other ship in the SW universe has anything really similar is a good sign that they generally use something else anyway.

Three things.

1.) the Y-wings aren't quite the "aerodynamic monstrosity" they're described as. With all the plating and coverings on, they're actually more aerodynamic than many of the other fighter craft in the original trilogy. Look up the "clone war era" Y-wings online (although they were always designed to have been older craft, heavily modified).

2.) The "thrust vector" thing is really the key for making the way Star Wars craft move be considered realistic. I can't think of a single craft in the SW universe that has only ONE engine or engine nozzle. So, arguably, all of them are simply vectoring thrust to change direction. Not necessarily through some "vector vane" like the Y-wing, but through manipulation of multiple engines. A-wings, I think, have similar vector vanes, though. Or something that looks like them.

3.) Y-wings are not nimble or maneuverable. This is not open for debate. Y-wings are, as I refer to them, "lead sleds." They're heavily armored and, for their time, heavily armed, but they are slower than molasses in winter and they turn REALLY slowly.



As a separate matter, on the issue of "why not a bottle of hairspray?" the issue is....sort of related to gravity and atmosphere.


Atmosphere creates resistance. It's molecules bumping against molecules, right? It's the same reason why you can't move your hand as quickly through water as you can through the air: more resistance. But that's more in the sense of "I put something in front of you so that you can't move ahead."

Gravity, on the other hand, is a force (not THE Force). Gravity is basically the attraction of mass to mass, right? So, the reason why we all fall to earth is because the earth is way bigger than us, and exerts more force over us. On the other hand, the reason the Earth doesn't go spinning off into the void of space is because the sun is so much bigger that it's keeping the earth in orbit. Again, it's the application of force.

When you say "but you have no gravity in space", technically that's not true. Gravity exists everywhere. You don't have PLANETARY gravity exerting force on you (unless you fall into one's gravitational field sufficient that it noticeably affects you). But there's still gravity.

As long as you have an object that has mass, moving it in any direction will require the application of force. You may need LESS force to move an object with no resistance from atmosphere and no planetary gravitational force being exerted on it, but you still need force.

If your object is moving in a given direction in a straight line, and you want to stop it cold, you'd need to exert sufficient force in the opposite direction to stop it. I don't recall the equations involved, but basically, you still need sufficient force to counteract the previous force applied.

 

[Nwerke]

Solo, it wasn't me who described them as monstrosities. I quite like the Clone Wars line art, but the final CG implementation - that's a different ship, unfortunately. It's in a "you can't get there from here" bracket of difference, and not quite as nice as the line art to boot. Oh well.

As for older - the X-wings were intended to be old, patched-up wrecks, too...

A-wings have a ring; it doesn't appear to be vectorable. It might be some kind of physically static MHD vectoring device or something I guess. Simple thrust variation would provide attitude control only in the plane of the engines, for a twin-engine craft like the A-wing, TIEs or, say, Tydirium.

Y-wings do just fine in the movies - they keep up with everything else. It's only in the games that all that EU stuff about them being older and slower comes into play. (I loved X-Wing too, BTW. Need to install an emulator and play it again!)

 

[Solo4114]

Solo, it wasn't me who described them as monstrosities. I quite like the Clone Wars line art, but the final CG implementation - that's a different ship, unfortunately. It's in a "you can't get there from here" bracket of difference, and not quite as nice as the line art to boot. Oh well.

Oh, I know. I forgot that the board doesn't include previous quotes. Sorry!

I've only seen the pics of the clone era Y-wing on Wookieepedia, but it looked interesting. You can see the evolution of the Y-wing as a craft through it. I thought they did a pretty good job overall.

I still hate flying the damn things, though.

As for older - the X-wings were intended to be old, patched-up wrecks, too...

A-wings have a ring; it doesn't appear to be vectorable. It might be some kind of physically static MHD vectoring device or something I guess. Simple thrust variation would provide attitude control only in the plane of the engines, for a twin-engine craft like the A-wing, TIEs or, say, Tydirium.

I think it depends on which bit of EU fluff you read. Or maybe I'm thinking of the ability for the guns to move? I don't know. All I know is that it's tough to beat the A-wing as a standard interceptor (note: T/As are what I'd consider space superiority fighters, and T/Ds are, well, god mode).

Y-wings do just fine in the movies - they keep up with everything else. It's only in the games that all that EU stuff about them being older and slower comes into play. (I loved X-Wing too, BTW. Need to install an emulator and play it again!)

The Y-wings in the films seem to be "meat on the table" for enemy fighters. They keep pace in terms of their overall speed, but we never see them dogfight. Hell, we never see them fire a shot in any of the films.

FYI, you don't necessarily need an EMU to run the X-wing games if you can snag a copy of the X-Wing Trilogy or X-Wing Collector's Series. If you want the full DOS experience, though, yeah, you need to be running DOSBOX or perhaps SCUMMVM. The updated versions (Xwing95 and Tie95) are great, but they don't have all the take-off/landing animations (so you don't see your shot up craft -- something I loved in the X-wing games), and you don't get to assign other pilots to your squadron.


I keep hoping someone will eventually do a fully updated version of those games, but I think that's wishful thinking (since no one really makes space sims, and LucasArts is all about the clone era or KOTOR era now...).

 

[Nwerke]

Heh, that makes sense of it.

Agree - the CW be-fairinged Y-wing is far better than the Dorling Kindersley version. I just wish they hadn't introduced the changes to the canopy and turret, or the 'curl' to the 'wingtips'. (In the lineart there's a simple, almost ogival curve from the cockpit to the engines; it looks a lot nicer.) Also, the final version has a solid filled-in nose gun area - that's just weird.

Ta for the emu tips. I hope for updated versions too - but if we ever get them, we'll also get a boxload of un-stomacheable latter-day EU/prequel garbage into the bargain, I'm afraid.

 

[Sith_241]

Three things.

1.) the Y-wings aren't quite the "aerodynamic monstrosity" they're described as. With all the plating and coverings on, they're actually more aerodynamic than many of the other fighter craft in the original trilogy. Look up the "clone war era" Y-wings online (although they were always designed to have been older craft, heavily modified).

2.) The "thrust vector" thing is really the key for making the way Star Wars craft move be considered realistic. I can't think of a single craft in the SW universe that has only ONE engine or engine nozzle. So, arguably, all of them are simply vectoring thrust to change direction. Not necessarily through some "vector vane" like the Y-wing, but through manipulation of multiple engines. A-wings, I think, have similar vector vanes, though. Or something that looks like them.

3.) Y-wings are not nimble or maneuverable. This is not open for debate. Y-wings are, as I refer to them, "lead sleds." They're heavily armored and, for their time, heavily armed, but they are slower than molasses in winter and they turn REALLY slowly.



As a separate matter, on the issue of "why not a bottle of hairspray?" the issue is....sort of related to gravity and atmosphere.


Atmosphere creates resistance. It's molecules bumping against molecules, right? It's the same reason why you can't move your hand as quickly through water as you can through the air: more resistance. But that's more in the sense of "I put something in front of you so that you can't move ahead."

Gravity, on the other hand, is a force (not THE Force). Gravity is basically the attraction of mass to mass, right? So, the reason why we all fall to earth is because the earth is way bigger than us, and exerts more force over us. On the other hand, the reason the Earth doesn't go spinning off into the void of space is because the sun is so much bigger that it's keeping the earth in orbit. Again, it's the application of force.

When you say "but you have no gravity in space", technically that's not true. Gravity exists everywhere. You don't have PLANETARY gravity exerting force on you (unless you fall into one's gravitational field sufficient that it noticeably affects you). But there's still gravity.

As long as you have an object that has mass, moving it in any direction will require the application of force. You may need LESS force to move an object with no resistance from atmosphere and no planetary gravitational force being exerted on it, but you still need force.

If your object is moving in a given direction in a straight line, and you want to stop it cold, you'd need to exert sufficient force in the opposite direction to stop it. I don't recall the equations involved, but basically, you still need sufficient force to counteract the previous force applied.

Your explanations of gravity are somewhat close but not quite correct.

Also, you could in fact propel a spaceship quite well with hairspray...provided you had enough.

 

[Stinky Dragon]

What I'm trying to grasp is why it takes anything more than a can of hairspray to maneuver any ship, regardless of size. What's keeping that ship from instantaneous direction change? There's no friction and no gravity, so there's nothing pushing against it and nothing pulling it towards it.

The maneuverability is certainly dependent on mass regardless of whether or not the ship is in a vacuum. It's a basic equation, but F = MA has everything you need to describe the situation. Acceleration is just a change in velocity, which could be either a directional change or a change in the magnitude (speed). If you fix the force applied, say by the can of hairspray, but change the mass, the acceleration would also change. So if you used the same can of hairspray on a Star Destroyer and an X-Wing, the Star Destroyer would have a much smaller change in direction since it has a much larger mass.

 

[Sith_241]

The maneuverability is certainly dependent on mass regardless of whether or not the ship is in a vacuum. It's a basic equation, but F = MA has everything you need to describe the situation. Acceleration is just a change in velocity, which could be either a directional change or a change in the magnitude (speed). If you fix the force applied, say by the can of hairspray, but change the mass, the acceleration would also change. So if you used the same can of hairspray on a Star Destroyer and an X-Wing, the Star Destroyer would have a much smaller change in direction since it has a much larger mass.

You just need a BIGGER can of hairspray on a SD, that's all! :lol

Or you could just thrust longer with the same size hairspray nozzle to achieve the same effect in a longer time period. But what fun is that?


Keep in mind that aerodynamic maneuverability is governed by different forces entirely. Yes, mass plays a part but is less insignificant in comparison with some other forces acting on things.