Bad design in Star Wars

[Simon_Jester]

Would it need more exhaust vents? It's not just to get rid of excess heat, you can do that with radiators (and with neutrino radiators you could even bury them deep in the hull) which wouldn't need a physical conduit to the core. It must be for getting rid of something physical, like hot gases. Would the reactor necessarily produce so much of those that more (perhaps many more) shafts would be necessary? (Honest question-I really don't know).

No way to be sure. But the sheer scale of the Death Star's power supply is staggering, so I'd strongly expect the reactor byproducts to be comparably staggering. Much of that may get blown off by means other than the exhaust port(s). But I find it far more plausible that there are many exhaust ports, only one of which offers a convenient target (the others being blocked by physical gratings or in exposed positions), than that there's only one total for the whole planetoid-sized battle station.

As for the winding/zig-zagging exhaust shat, wouldn't that severely reduce the throughput of the shaft requiring a LARGER one that would be considerably EASIER to hit? I suspect that a shaft that can phase 70,000g turn torpedoes is bound to be the next best thing to nonfunctional.

Agreed. There may be gentle kinks in the ductwork for structural reasons, but the thing should be at least vaguely straightish; a well-designed guided missile shouldn't have much trouble navigating it if it has the performance we see in the movie.

So the shaft might zig-zag with a manageable radius of curvature for the torpedoes and still have everything work well enough.

[erik_t]

As for the winding/zig-zagging exhaust shat, wouldn't that severely reduce the throughput of the shaft requiring a LARGER one that would be considerably EASIER to hit? I suspect that a shaft that can phase 70,000g turn torpedoes is bound to be the next best thing to nonfunctional.

Agreed. There may be gentle kinks in the ductwork for structural reasons, but the thing should be at least vaguely straightish; a well-designed guided missile shouldn't have much trouble navigating it if it has the performance we see in the movie.

Um, what? Proton torpedos have some maximum delta-V normal to their direction of motion. We don't know what that number is, but to say they can make one turn, therefore they can make an arbitrary number of them... are you on stupid pills today?

[Batman]

Yeah. Expecting thermos-sized torpedoes that can do 70,000 g hairpin turns to navigate an essentially straight shaft several metres wide is obviously madness.

[erik_t]

And Batman also misses the clue-train. Lateral acceleration capability is important, but no more so than total lateral impulse available. Yes, a very nearly straight shaft might cause a proton torpedo to hit the wall if the total maneuvering capability had been reached. Never mind that I didn't say a damned thing about a straight shaft... a few sharp 90deg corners would have a negligible effect on the shaft throughput compared to hundreds of km of straight shaft.

[Batman]

And Batman also misses the clue-train. Lateral acceleration capability is important, but no more so than total lateral impulse available. Yes, a very nearly straight shaft might cause a proton torpedo to hit the wall if the total maneuvering capability had been reached.

Or it may be a cakewalk if it hasn't. Especially as there is absolutely no reason to assume the torpedoes total maneuvering capacity HAS been reached.

Never mind that I didn't say a damned thing about a straight shaft... a few sharp 90deg corners would have a negligible effect on the shaft throughput compared to hundreds of km of straight shaft.

I very much suspect a few sharp 90 degree corners WOULD have noticeable effect on the shaft's throughput while doing beans about a proton torpedo reaching the reactor.

[erik_t]

Or it may be a cakewalk if it hasn't. Especially as there is absolutely no reason to assume the torpedoes total maneuvering capacity HAS been reached.

Of course. The initial thought on the matter, which I admit to having not quoted, was Simon_Jester's statement: "Why would a torpedo that can make one turn be unable to make several? That makes no sense."

This statement in itself is obviously nonsensical, based on what we know about how a Newtonian-maneuvering object must act in a vacuum.

Never mind that I didn't say a damned thing about a straight shaft... a few sharp 90deg corners would have a negligible effect on the shaft throughput compared to hundreds of km of straight shaft.

I very much suspect a few sharp 90 degree corners WOULD have noticeable effect on the shaft's throughput while doing beans about a proton torpedo reaching the reactor.

If we are suspecting the output is a diffuse gas (so as to not be handled by magical neutrino emitters), then you may log that as my professional opinion as a fluid mechanician. Several short-radius bends would have a negligible effect on the overall pressure loss compared to hundreds of km of fully-developed channel flow.

[Batman]

Or it may be a cakewalk if it hasn't. Especially as there is absolutely no reason to assume the torpedoes total maneuvering capacity HAS been reached.

Of course. The initial thought on the matter, which I admit to having not quoted, was Simon_Jester's statement: "Why would a torpedo that can make one turn be unable to make several? That makes no sense."
This statement in itself is obviously nonsensical, based on what we know about how a Newtonian-maneuvering object must act in a vacuum.

Patently false.Yes, an object making that kind of turn MAY be unable to make that kind (or any kind) of turn ever again. It being an object that has to follow Newton's laws however has absolutely no bearing on that.

Never mind that I didn't say a damned thing about a straight shaft... a few sharp 90deg corners would have a negligible effect on the shaft throughput compared to hundreds of km of straight shaft.

I very much suspect a few sharp 90 degree corners WOULD have noticeable effect on the shaft's throughput while doing beans about a proton torpedo reaching the reactor.

If we are suspecting the output is a diffuse gas (so as to not be handled by magical neutrino emitters), then you may log that as my professional opinion as a fluid mechanician. Several short-radius bends would have a negligible effect on the overall pressure loss compared to hundreds of km of fully-developed channel flow.

Err-you're not GETTING hundreds of km of channel flow WITHOUT plenty of bends because, you see, DSI was only 160 km across.

[bz249]

And if they had the choice to evacuate before the Death Star could blow up the planet, why the hell didn't they do it anyway and send the X-Wings in, instead of just sitting there while the Death Star moved into firing position? They already knew the Death Star had plenty of TIE fighters and shit, so they had to know that their plan might fail.

Even if you thought your X-Wing plan had a 99% chance of working or whatever, you'd have to be a complete fool to just sit there and do nothing instead of boarding a transport and commanding the battle from safely out of superlaser range.

Because I would be meaningless, after the destruction of the Alderaan the Empire had won. All the escaping Rebel leaders could hope that they rot it an ass-end shithole until someone decides to make some money by giving them to the Imperial authorities. Look what has happened to the Saddam Hussein guy. Or do you seriously think that there will be anyone who will openly or even covertly support a rebellion against the Empire which has a weapon(s) capable of defeating the most advanced planetary shield and destroying a planet?

If Tarkin would be less pompous and had less desire for a "military victory" than all would have been over. By offering a battle just the day after the destruction of the Alderaan, he offered a chance for the Rebels. If the Yavin battle happens six month later it would be insignificant, till that time a firm control over the Galaxy would have been established. So it was a one and only opportunity. Not destroying the Death Star means game over

[erik_t]

Or it may be a cakewalk if it hasn't. Especially as there is absolutely no reason to assume the torpedoes total maneuvering capacity HAS been reached.

Of course. The initial thought on the matter, which I admit to having not quoted, was Simon_Jester's statement: "Why would a torpedo that can make one turn be unable to make several? That makes no sense."
This statement in itself is obviously nonsensical, based on what we know about how a Newtonian-maneuvering object must act in a vacuum.

Patently false.Yes, an object making that kind of turn MAY be unable to make that kind (or any kind) of turn ever again. It being an object that has to follow Newton's laws however has absolutely no bearing on that.

Never mind that I didn't say a damned thing about a straight shaft... a few sharp 90deg corners would have a negligible effect on the shaft throughput compared to hundreds of km of straight shaft.

I very much suspect a few sharp 90 degree corners WOULD have noticeable effect on the shaft's throughput while doing beans about a proton torpedo reaching the reactor.

If we are suspecting the output is a diffuse gas (so as to not be handled by magical neutrino emitters), then you may log that as my professional opinion as a fluid mechanician. Several short-radius bends would have a negligible effect on the overall pressure loss compared to hundreds of km of fully-developed channel flow.

Err-you're not GETTING hundreds of km of channel flow WITHOUT plenty of bends because, you see, DSI was only 160 km across.

Excuse me, dozens of KM. You're still talking about a rather absurd channel aspect ratio on the order of 10^4, and my statement remains unchanged.

[Simon_Jester]

Um, what? Proton torpedos have some maximum delta-V normal to their direction of motion. We don't know what that number is, but to say they can make one turn, therefore they can make an arbitrary number of them... are you on stupid pills today?

If the entire exhaust shaft were sharp two-meter right angle turns all the way down, it's a fair bet that the proton torpedoes would run out of delta-V on the way down; the amount of energy release required would probably be comparable to what's carried in the torpedo warhead.

But even given your "professional opinion as a fluid mathematician"*, would you generalize that conclusion to a shaft that was short-radius bends all the way down, for something on the order of fifty kilometers? The mere fact that they cut a hole in the hull and armor belts of the station for the exhaust port indicates that the exhaust is not some sort of neutrino or WIMP or other particle that can travel through walls, and if the exhaust is hot gas there has to be some limit on how many bends you can put in it.

I will admit to being surprised that even a few bends wouldn't be a significant problem; I thought that the shaft would be restricted to bends so shallow that it beggars belief that the torpedo would not have enough reserve maneuvering capability to handle them. But there is no evidence whatsoever that the torpedo is anywhere near its limit. The torpedo's total lateral delta-V is a complete unknown, and since no one displays any concern about the 'risk' that it will run out of maneuvering power/fuel/whatever on the way down, I think it likely that the sharp turn we saw it make was far within its design parameters, with plenty more lateral delta-V where that came from.

Which was the original point: if the shaft is not bent and kinked to the point where it loses all utility for its designed purpose, it almost has to be navigable by torpedoes that can reliably make a 70000 g turn and that have some analogue of terrain-following radar.

*Not repeat not sarcasm, I'm using quotations because it is a quote.
_________

Of course. The initial thought on the matter, which I admit to having not quoted, was Simon_Jester's statement: "Why would a torpedo that can make one turn be unable to make several? That makes no sense."

This statement in itself is obviously nonsensical, based on what we know about how a Newtonian-maneuvering object must act in a vacuum.

Problem with that analysis: proton torpedoes, by all appearances, have a reactionless drive of some sort. We don't see any ejecta coming off them at right angles to the turn as they round the corner, and the kind of rocket exhaust needed to make a 70000 g turn ought to be very visible in its own right.

So while anything and everything must have limited delta-V in any given direction based on what we know about Newtonian physics, I can only conclude that whoever builds proton torpedoes for a living knows some physics Newton doesn't. There's almost certainly still a limit, but we have absolutely no reference point for guessing what the limit is. And since the fighter pilots express no concern about the torpedo's ability to make the turns assuming they can get it on target at all, I doubt that the single turn we see is anywhere near that limit.
___________

And if they had the choice to evacuate before the Death Star could blow up the planet, why the hell didn't they do it anyway and send the X-Wings in, instead of just sitting there while the Death Star moved into firing position?...

Because I would be meaningless, after the destruction of the Alderaan the Empire had won. All the escaping Rebel leaders could hope that they rot it an ass-end shithole until someone decides to make some money by giving them to the Imperial authorities. Look what has happened to the Saddam Hussein guy...

In real life, guerillas and rebels generally don't give up all hope of survival based on a binary decision like that, with good reason. The fact that the other side has won a crushing victory in public opinion-space doesn't mean they won't screw up three months from now and throw it all away. Maybe the Death Star will have a reactor accident and blow itself up. Maybe Giant Monsters from Beyond the Galaxy will invade and shake everything up. Maybe the Emperor will choke on a pretzel. Who knows?

Yes, it's unlikely, but if you're determined enough to fight a guerilla war against overwhelming force in the first place, you don't lose that determination overnight. Remember that the Rebels had no specific plan to win the war before they found out about the Death Star, either. All they could do was try to survive, hang on, and look for some kind of weakness. Even with the Death Star operational, the possibility of such a weakness emerging still exists, at least in principle.

So Leia, Dodonna, and any other Rebel leaders on the planet wouldn't just sit there and wait to be blown apart if they had an option of escaping. Given the real life performance of actual resistance and guerilla movements, they'd at least be trying to hold on for a few more months in hopes that they'd get lucky and somehow (by unspecified means) win.

That's one reason guerillas are so troublesome: they don't all come out of the hills and surrender the moment you win a big battle that most people agree is "game over, you win." Many will keep fighting, even if they're fooling themselves about their eventual hope of victory. Especially if they know you're going to kill them anyway. Making them lay down their arms is not as simple as winning one big battle or acquiring one devastating weapon.

Therefore, I think that the reason the rebels made no effort at escape is that Exar Kun is wrong, and their backs really are to the wall tactically. They physically cannot escape in the minutes they have before the Death Star hits them. It's not that they've suddenly gone fatalistic all over and decided that they might as well die with their base, it's that they have no viable means of escape. That sort of attitude would be completely out of character for the central cadre of a guerilla movement; if they thought that way they'd never have wound up on Yavin in the first place.

[Drooling Iguana]

Does the Death Star carry any larger ships that would've been able to chase down and destroy any transports that left the rebel base while the Death Star was still on the other side of Yavin? TIEs alone wouldn't be very useful for that and we didn't see the DS launch anything else in the films. Does the EU say anything about this?

[erik_t]

If the entire exhaust shaft were sharp two-meter right angle turns all the way down, it's a fair bet that the proton torpedoes would run out of delta-V on the way down; the amount of energy release required would probably be comparable to what's carried in the torpedo warhead.

But even given your "professional opinion as a fluid mathematician"*, would you generalize that conclusion to a shaft that was short-radius bends all the way down, for something on the order of fifty kilometers?

No, certainly not. The relevant concern, which you've already independently deduced, is that any features on the order of meters will be swamped by features on the order of tens of kilometers.

The mere fact that they cut a hole in the hull and armor belts of the station for the exhaust port indicates that the exhaust is not some sort of neutrino or WIMP or other particle that can travel through walls, and if the exhaust is hot gas there has to be some limit on how many bends you can put in it.

I will admit to being surprised that even a few bends wouldn't be a significant problem; I thought that the shaft would be restricted to bends so shallow that it beggars belief that the torpedo would not have enough reserve maneuvering capability to handle them. But there is no evidence whatsoever that the torpedo is anywhere near its limit. The torpedo's total lateral delta-V is a complete unknown, and since no one displays any concern about the 'risk' that it will run out of maneuvering power/fuel/whatever on the way down, I think it likely that the sharp turn we saw it make was far within its design parameters, with plenty more lateral delta-V where that came from.

Which was the original point: if the shaft is not bent and kinked to the point where it loses all utility for its designed purpose, it almost has to be navigable by torpedoes that can reliably make a 70000 g turn and that have some analogue of terrain-following radar.

This would certainly be the case if these torpedos were designed as tunnel-following strike weapons, which is the assumption you've implicitly made. I think that's a dangerous and highly inaccurate line of thinking. As we've seen torpedos used, why would they have a guidance system amenable to following, within a meter, a small tunnel? What RFP would produce such a inanely special-purpose weapon, and even if such did exist, why would the Rebellion spend their precious funding/access on weapons like that?

Torpedos certainly have some impressive maneuvering capability, but IMHO there's no reason to assume a stupendous quantity of lateral delta-V. They seem most useful for strikes on large shielded starships, and any lateral delta-V beyond a few multiples of (say) a frigate's capability (which for our purposes would be time-limited, based on some notional torpedo flight-time) would be wasted. That space could be better used for a larger warhead, or the torpedo itself could shrink.

So while anything and everything must have limited delta-V in any given direction based on what we know about Newtonian physics, I can only conclude that whoever builds proton torpedoes for a living knows some physics Newton doesn't. There's almost certainly still a limit, but we have absolutely no reference point for guessing what the limit is. And since the fighter pilots express no concern about the torpedo's ability to make the turns assuming they can get it on target at all, I doubt that the single turn we see is anywhere near that limit.

I categorically reject the idea that proton torpedos utilize a heretofore-unseen propulsion technology that is independently at odds with the most fundamental of physical laws, unless there is absolutely no way around it. As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.

[Anguirus]

The shaft is also obviously not within the equator, so that's either another shaft, or the diagram shown here is way off.

They are not flying down the equatorial trench. The equatorial trench is HUGE, that's where the Falcon docked (and according to the EU, shit like strike cruisers dock there).

According to that diagram, other EU, and I think even the novelization, they are flying down a polar trench.

The EU (Death Star) also posits an explanation for the design "flaw" and why the small port is only in one of the polar trenches: an overconservative Wookiee construction engineer insists on building it in and knows how to navigate bureaucracy better than the one architect who protests it. The book actually leaves it very ambiguous whether the Wookiee was some kind of Fifth Columnist, as it is noted a few times that despite the fact that he was conscripted he appeared very dedicated to the project. He also dies of radiation poisoning before the plans are leaked to the Rebels.

[Batman]

This would certainly be the case if these torpedos were designed as tunnel-following strike weapons, which is the assumption you've implicitly made. I think that's a dangerous and highly inaccurate line of thinking. As we've seen torpedos used, why would they have a guidance system amenable to following, within a meter, a small tunnel? What RFP would produce such a inanely special-purpose weapon, and even if such did exist, why would the Rebellion spend their precious funding/access on weapons like that?

What's special purpose about a guidance system that's accurate to under a meter? Heck we're close to achieving that TODAY. You want to shoot at specific ship systems instead of just some random part of the hull you NEED that kind of accuracy.

Torpedos certainly have some impressive maneuvering capability, but IMHO there's no reason to assume a stupendous quantity of lateral delta-V.

That'd be the part were they can successfully track starfighters that definitely do.

They seem most useful for strikes on large shielded starships, and any lateral delta-V beyond a few multiples of (say) a frigate's capability (which for our purposes would be time-limited, based on some notional torpedo flight-time) would be wasted. That space could be better used for a larger warhead, or the torpedo itself could shrink.

OR there could be different kinds of proton torpedoes, some of which are designed to deal with small agile targets and would thus have the lateral delta-v needed to navigate a twisted shaft.

So while anything and everything must have limited delta-V in any given direction based on what we know about Newtonian physics, I can only conclude that whoever builds proton torpedoes for a living knows some physics Newton doesn't. There's almost certainly still a limit, but we have absolutely no reference point for guessing what the limit is. And since the fighter pilots express no concern about the torpedo's ability to make the turns assuming they can get it on target at all, I doubt that the single turn we see is anywhere near that limit.

I categorically reject the idea that proton torpedos utilize a heretofore-unseen propulsion technology that is independently at odds with the most fundamental of physical laws, unless there is absolutely no way around it.
As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.

Um-no it must not. We ALREADY see two drive systems that aren't reaction-based in the movies-hyperdrive and repulsors. As Simon_Jester pointed out the inevitable side effects that would go with a reaction engine of that power are curiously absent from the movie.

Does the Death Star carry any larger ships that would've been able to chase down and destroy any transports that left the rebel base while the Death Star was still on the other side of Yavin? TIEs alone wouldn't be very useful for that and we didn't see the DS launch anything else in the films. Does the EU say anything about this?

EGVV says it carries 4 strike cruisers (or at least it used to) and I don't see why TIEs would be incapable of this. Anyway the DS might be able to prevent the escape without launching so much as a single ship-gravity well generators (does the EU have anything to say about this?)
Or maybe thanks to the short time between the arrival of the Falcon and the DS they couldn't get the escape transports prepped.

[erik_t]

This would certainly be the case if these torpedos were designed as tunnel-following strike weapons, which is the assumption you've implicitly made. I think that's a dangerous and highly inaccurate line of thinking. As we've seen torpedos used, why would they have a guidance system amenable to following, within a meter, a small tunnel? What RFP would produce such a inanely special-purpose weapon, and even if such did exist, why would the Rebellion spend their precious funding/access on weapons like that?

What's special purpose about a guidance system that's accurate to under a meter? Heck we're close to achieving that TODAY. You want to shoot at specific ship systems instead of just some random part of the hull you NEED that kind of accuracy.

Hitting an object to within a meter and navigating a predetermined course to within a meter are very, very different things. I invite you to consider Sea Skimmer's notes on issues related to TERCOM.

Torpedos certainly have some impressive maneuvering capability, but IMHO there's no reason to assume a stupendous quantity of lateral delta-V.

That'd be the part were they can successfully track starfighters that definitely do.
...
OR there could be different kinds of proton torpedoes, some of which are designed to deal with small agile targets and would thus have the lateral delta-v needed to navigate a twisted shaft.

SW fighters have at no point demonstrated maneuverability that would require a tracking weapon to rotate its velocity vector several times over.

As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.

Um-no it must not. We ALREADY see two drive systems that aren't reaction-based in the movies-hyperdrive and repulsors. As Simon_Jester pointed out the inevitable side effects that would go with a reaction engine of that power are curiously absent from the movie.

Repulsors aren't reaction-based? What, pray tell, are they repulsing, then?

(I concede that hyperdrive is a special ball of wax, but it already was for causality reasons)

Do you appreciate the degree to which everything would be fucked if proton torpedos have their own little method of sublight propulsion which ignores conservation of momentum? You really think that introducing this new term solves more problems than it creates?

As for not seeing ejecta from lateral rockets on the proton torpedos, we don't see any exhaust plume from most SW thrusters. The only contrary example I can think of off the top of my head was the Falcon's little extra burst as it headed back towards the ISD in TESB.

[Batman]

What's special purpose about a guidance system that's accurate to under a meter? Heck we're close to achieving that TODAY. You want to shoot at specific ship systems instead of just some random part of the hull you NEED that kind of accuracy.

Hitting an object to within a meter and navigating a predetermined course to within a meter are very, very different things. I invite you to consider Sea Skimmer's notes on issues related to TERCOM.

If the torpedo can determine its position relative to the target down to a metre, it can determine its position relative to the Valendamned shaft walls down to a metre.

Torpedos certainly have some impressive maneuvering capability, but IMHO there's no reason to assume a stupendous quantity of lateral delta-V.

That'd be the part were they can successfully track starfighters that definitely do.
...
OR there could be different kinds of proton torpedoes, some of which are designed to deal with small agile targets and would thus have the lateral delta-v needed to navigate a twisted shaft.

SW fighters have at no point demonstrated maneuverability that would require a tracking weapon to rotate its velocity vector several times over.

Ahem. 1000s of gs of linear acceleration, which means 1000s of gs of lateral acceleration.

As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.

Um-no it must not. We ALREADY see two drive systems that aren't reaction-based in the movies-hyperdrive and repulsors. As Simon_Jester pointed out the inevitable side effects that would go with a reaction engine of that power are curiously absent from the movie.

Repulsors aren't reaction-based? What, pray tell, are they repulsing, then?

Reaction engine=throws stuff out back to move vehicle forward. Where, pray tell, do repulsors do that?

Do you appreciate the degree to which everything would be fucked if proton torpedos have their own little method of sublight propulsion which ignores conservation of momentum?

Who says they ignore CoM?

As for not seeing ejecta from lateral rockets on the proton torpedos, we don't see any exhaust plume from most SW thrusters. The only contrary example I can think of off the top of my head was the Falcon's little extra burst as it headed back towards the ISD in TESB.

Fair enough complaint.

[erik_t]

If the torpedo can determine its position relative to the target down to a metre, it can determine its position relative to the Valendamned shaft walls down to a metre.

Sure it can, but who says the torpedo can determine its position relative to the target down to a meter throughout the flight? You're assuming that a proton torpedo thinks like a JDAM, knowing its location and the target's location, then plotting an appropriate trajectory between the two. Since there's no magic space-GPS, it seems far more likely that torpedo homes as a modern-day fire-and-forget SAM does. In this case, the missile would only know the relative rate at which the projected impact point and the target are changing; it then adjusts to make this rate constantly zero. The latter is, in any case, much more suited to attacking targets that are maneuvering more rapidly than a beat-up Iraqi truck.

If, then, the torpedo does not have a great idea of where it is at all times (and, as above, why would it need to?), it would need some kind of (eg) circumferential laser range-detector with a superbly high data rate in order to follow the contours of a tunnel. Again, this is a technology that is not outside the realm of the possible, but it would be completely unnecessary for anything except flying down a tunnel.

SW fighters have at no point demonstrated maneuverability that would require a tracking weapon to rotate its velocity vector several times over.

Ahem. 1000s of gs of linear acceleration, which means 1000s of gs of lateral acceleration.

You and I both know that, for whatever reason, SWverse targets generally do not maneuver in this manner. A proton torpedo without the absurd delta-V you posit could successfully engage literally every possible target seen in the movies. Why, then, build in this capability when it would cost money and volume?

As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.

Repulsors aren't reaction-based? What, pray tell, are they repulsing, then?

Reaction engine=throws stuff out back to move vehicle forward. Where, pray tell, do repulsors do that?

I don't know why you choose to interpret "reaction" as "jet of gas". A repulsor functions based on action-reaction forces akin to gravity. If there's nothing against which this action-reaction force pair can act, then the repulsor does not function. There is no characteristic velocity in a repulsor context other than the relative velocities between objects (or, I suppose, c). This allows us to calculate a maximum propulsive efficiency and therefore put a cap on the maximum situational delta-V allowed by any given power source within the torpedo.

Do you appreciate the degree to which everything would be fucked if proton torpedos have their own little method of sublight propulsion which ignores conservation of momentum?

Who says they ignore CoM?

Anyone who says X engine does not function with action-reaction forces is ignoring CoM.

[FSTargetDrone]

They are not flying down the equatorial trench. The equatorial trench is HUGE, that's where the Falcon docked (and according to the EU, shit like strike cruisers dock there).

According to that diagram, other EU, and I think even the novelization, they are flying down a polar trench.

Yes, I think you are right. I was thinking about the briefing video showing the DS and the trench, as well as that other image taken from the TL section on the main site (which I believe IS from the ICS book--the font appears to be the same) and the much narrower trench that the fighters use. It cannot be the same trench. We could probably estimate its typical width using the views of the Tie Fighters and other ships seen from directly forward or behind, but in any case it must be narrow enough as to be invisible from the same distances that the equatorial trench is discernible. Also, the shaft visible in the image might represent a "typical" shaft, if we assume there is more than one.

Problem with that analysis: proton torpedoes, by all appearances, have a reactionless drive of some sort. We don't see any ejecta coming off them at right angles to the turn as they round the corner, and the kind of rocket exhaust needed to make a 70000 g turn ought to be very visible in its own right.

The proton torpedoes do exhibit visible exhaust as they travel along the trench (note the longer trail seen here as compared to below):



And as they enter the opening:





(^^ note the blast marks from the previously-launched torpedoes)



Advance the clip below to about 1:50 to see the launch of the torpedoes...



Now, we can debate what that glowing material surrounding the torpedoes is. Frankly, to me, they look like flames swirling off of catapulted burning bales of hay ( ), but there is definitely something coming off of those torpedoes during the whole time they are visible, both during the launch and when they make the turn. Is it indicative enough of what the drive onboard is supposed to be doing to make the turn? I'll leave it to you guys to hash out. Just wanted to put this in here. Hopefully it's useful.

ADDENDUM:

The Wookipedia page about the torpedoes. The first image on that page is not taken from the movie, incidentally. It looks to be from the Behind The Magic CD.

[Batman]

If the torpedo can determine its position relative to the target down to a metre, it can determine its position relative to the Valendamned shaft walls down to a metre.

Sure it can, but who says the torpedo can determine its position relative to the target down to a meter throughout the flight?

Why would it need to? All it needs to know is its own position for the time being.

You're assuming that a proton torpedo thinks like a JDAM, knowing its location and the target's location, then plotting an appropriate trajectory between the two.

No, I'm thinking that a proton torpedo should be easily able to navigate a shaft it can clearly see when modern day missiles probably could.

Since there's no magic space-GPS, it seems far more likely that torpedo homes as a modern-day fire-and-forget SAM does.

What kind? Active radar, heatseeker, electro-optical? And all it needs to know its position relative to the target (which it DOESN'T need to know to navigate the shaft BTW) is INS. YOU are assuming it can only have one guidance system when modern day missiles already combine several.

SW fighters have at no point demonstrated maneuverability that would require a tracking weapon to rotate its velocity vector several times over.

Ahem. 1000s of gs of linear acceleration, which means 1000s of gs of lateral acceleration.

You and I both know that, for whatever reason, SWverse targets generally do not maneuver in this manner.

They CAN maneuver this way. The torpedoes are designed to deal with that.

A proton torpedo without the absurd delta-V you posit could successfully engage literally every possible target seen in the movies. Why, then, build in this capability when it would cost money and volume?

Because they need it to hit the targets they're designed to hit. That we don't see them make use of that maneuverability in the movies is immaterial.

As far as I'm concerned, there's nowhere near enough hard evidence to force us to disregard conservation of momentum. We don't know how the system works, but it is and must be a reaction-based thruster.
Repulsors aren't reaction-based? What, pray tell, are they repulsing, then?

Reaction engine=throws stuff out back to move vehicle forward. Where, pray tell, do repulsors do that?

I don't know why you choose to interpret "reaction" as "jet of gas".

Because that's the very definition of a reaction engine. Repulsors don't.

[Simon_Jester]

(I concede that hyperdrive is a special ball of wax, but it already was for causality reasons)

Do you appreciate the degree to which everything would be fucked if proton torpedos have their own little method of sublight propulsion which ignores conservation of momentum? You really think that introducing this new term solves more problems than it creates?

Trouble is, I think these problems have already been created for us whether we want them or not. Among other things, we are still stuck with the question of what happens when Star Wars ships moving toward each other use the (very canonically established) FTL comms they have. That creates a causality violation all by itself, at which point our assumptions about frame of reference have to start bending into knots to preserve causality. Since frame of reference issues are the same ones created by momentum conservation violations, I have a sneaking suspicion that (to mix metaphors) you're trying to lock the barn door after the FTL starship has flown the coop.

As for not seeing ejecta from lateral rockets on the proton torpedos, we don't see any exhaust plume from most SW thrusters. The only contrary example I can think of off the top of my head was the Falcon's little extra burst as it headed back towards the ISD in TESB.

Yes, but we've definitely seen Star Wars craft accelerate in directions at an angle to any direction they could conceivably fire exhaust out of any visible nozzle. Hell, on takeoff they typically accelerate in directions that would require them to push rocket exhaust out through the hull! If they're doing that using some sort of variation on the tractor beam, fine... but there's plenty of material handy for a proton torpedo to use if it's making sharp turns via pressor beams.

The point being that a proton torpedo, however it makes turns, clearly does NOT make turns by ejecting matter in a direction opposite the direction it wants to go. The torpedoes trail some kind of fire-looking thing, but they do not give even the slightest sign of ejecting matter in the direction they'd need to make a turn into the shaft (in a plane perpendicular to the Death Star's surface, at about a 45° angle to the surface and a 135° angle to their line of flight). I called that a reactionless drive incautiously, but whatever it is, it isn't anything we know how to build. Working tractor beams are roughly as good an example of "physics we don't know" as reactionless drives.

That said, fine, proton torpedoes do not use reactionless drives. This was a slip of the tongue on my part. However, they DO use a system with unknown and high lateral delta-V capabilities, and one that operates on unknown physical principles, driven by an unknown power source.

All common sense suggests that there must be some limit on the torpedo's lateral delta-V, but I see no reason to assume that the limit is reached or even approached by the one turn we see it making. I don't believe for a minute that the torpedo could navigate an infinite number of bends. But I don't think it's reasonable to object that a reasonable number of bends in the exhaust shaft (which would have to be relatively few to avoid kinking the shaft into uselessness) could reliably stop torpedoes. We have only a lower bound on their capabilities, not an upper.
___________

Sure it can, but who says the torpedo can determine its position relative to the target down to a meter throughout the flight? You're assuming that a proton torpedo thinks like a JDAM, knowing its location and the target's location, then plotting an appropriate trajectory between the two. Since there's no magic space-GPS, it seems far more likely that torpedo homes as a modern-day fire-and-forget SAM does. In this case, the missile would only know the relative rate at which the projected impact point and the target are changing; it then adjusts to make this rate constantly zero. The latter is, in any case, much more suited to attacking targets that are maneuvering more rapidly than a beat-up Iraqi truck.

If, then, the torpedo does not have a great idea of where it is at all times (and, as above, why would it need to?),

Because it is also used as a bombardment weapon? Given that they have yields in the nuclear range, the fact that they are used as space superiority and antiship weapons does not mean they will not also have the equipment to work air-to-ground.

The fact that the Rebels even tried this trick indicates that they had confidence in the torpedo's ability to navigate the shaft. Since it would need the kind of sensor suite you describe* to do that at all, even if the tunnel was reasonably straight, I think you're plying Occam's Razor too hard when you suppose that the torpedo need not have such a sensor suite.

I do not know why the torpedo would be equipped to do such a thing. Perhaps it is a specialized weapon designed for air-to-surface or surface-to-surface work, that needs to follow terrain to a distant target, like a Tomahawk cruise missile. Perhaps it is a specialized weapon designed to be used against large space stations or capital ships, fired from close range and intended to target specific points (say, to fly up into the interior of a star destroyer's engines via the nozzles on the back). Perhaps it is designed to be the bane of all tunnel networks. I don't know. But I do know that the capability is strongly implied simply by the fact that the torpedoes are used for the mission in the first place, and that the only concern the pilots seem to have is getting the torpedoes into the hole at all, with the implication that if they can get the shot into the hole the rest is almost guaranteed.

*Circumferential laser-ranging, or some equivalent.
__________

Problem with that analysis: proton torpedoes, by all appearances, have a reactionless drive of some sort. We don't see any ejecta coming off them at right angles to the turn as they round the corner, and the kind of rocket exhaust needed to make a 70000 g turn ought to be very visible in its own right.

The proton torpedoes do exhibit visible exhaust as they travel along the trench (note the longer trail seen here as compared to below):
And as they enter the opening: (images deleted to save space)

That cannot be the exhaust of a reaction drive, because it's going in the wrong direction as the torpedoes round the corner. If I want to turn left with a reaction drive I must fire the engine forward and to the right, not simply behind me. It's impossible to make a turn while always firing the engine at a tangent to your line of flight, and the "exhaust" we see off the torpedoes is tangent to the line of flight.

I don't know what it is, but that fiery stuff coming off the torpedo is not rocket exhaust. Or if it is, it's completely irrelevant to the torpedoes' ability to make a sharp turn.

[FSTargetDrone]

That cannot be the exhaust of a reaction drive, because it's going in the wrong direction as the torpedoes round the corner. If I want to turn left with a reaction drive I must fire the engine forward and to the right, not simply behind me. It's impossible to make a turn while always firing the engine at a tangent to your line of flight, and the "exhaust" we see off the torpedoes is tangent to the line of flight.

I don't know what it is, but that fiery stuff coming off the torpedo is not rocket exhaust. Or if it is, it's completely irrelevant to the torpedoes' ability to make a sharp turn.

I understand. The launching/travel down the trench seems okay (if that's all we had--no turn), but as you suggest, the turn into the shaft looks strange.

They look just like a pair of fireballs, no? The torpedoes actually seem to cast light along the surface near and into the opening of the shaft.

[ExarKun]

That's not the point. When you design a station the size of a moon, you make sure it is hard to destroy by a single fighter.

Right, because single one man fighters are ALWAYS going around blowing up moon sized objects. I mean, that is a common problem. The Empire really should have focused on stopping a single fighter.

Man, where the fuck do you come up with this bullshit.

And in all your dumbass rantings, did it not once occur to you that no one actually knew about the secondary exhaust port? Other than whatever computer or engineer designed it, no one knew about it. Even the Imperials didn't know... "We've analyzed their attack sir, and there is a danger."

As for it being a design flaw, I'm not an engineer, but it seems like designing and building a straight exhaust port that is only two meters wide that is kilometers long, makes a hell of a lot more sense than putting unnecessary bends and curves in it. Even then, the designers had enough forethought to ray shield it specifically. Clearly, NO ONE, either engineer or military, felt that a projectile attack had any real hope of success, if it could even be tried. And as has been pointed out numerous times, it literally took a supernatural Force to make the shot successful.

And of course, we only have your say so that the torpedoes couldn't make the necessary maneuvers to make it down the exhaust shaft if there had been turns.
In fact, we can't even say for certain that the shaft DIDN'T have any turns in it. The simulation we see of the shaft and torpedo hit is obviously not to scale or in any way detailed, but hey, why actually watch the movies.

Yeah sorry dillhole, a design 'flaw' it is not.

It took me 5 minutes to attempt to recoup, by the way of deep concentration, the IQ I lost by reading this. I'm not sure it worked.
I didn't want to be mean so I didn't respond to the first post you made, but since you're being an arrogant douche bag, I'll strip your comment down into bits, and frankly, you're an embarrassment to your "side" in this argument cause your shit is so stupid it took me half an hour to decide whether to waste my life responding to this shit:

1. No one knew about the exhaust port except the computer or engineer who designed it

That's why it's not a design flaw? Holly Shit!!
Who do you think designed it but an engineering team? A team of engineers who should have discussed it, then taken it to their supervisor, then may be to a manager who is in charge of designing the reactor, then.....

2. As for it being a design flaw, I'm not an engineer, but it seems like designing and building a straight exhaust port that is only two meters wide that is kilometers long, makes a hell of a lot more sense than putting unnecessary bends and curves in it.
Of course you're not. Yeah, who needs curves, lets just make it easy for someone to drop a fucking torpedo down to a highly volatile reactor. While we're at it, lets expose the fuel tanks at a gas station so that some tool can throw down a cigarette butt. It will be easier to refuel and, I'm not an engineer, but it seems like it makes hell of a lot of more sense than the way it is now. Who needs unnecessary safety precautions?

3. And as has been pointed out numerous times, it literally took a supernatural Force to make the shot successful.
No it didn't. They felt they could do it anyways, no one knew about Luke's force. Why would it be hard to shoot a torpedo down a straight fucking shaft? If they felt they could not do it without supernatural powers, they would have packed up whatever bags they could get in time and left.

4. In fact, we can't even say for certain that the shaft DIDN'T have any turns in it. The simulation we see of the shaft and torpedo hit is obviously not to scale or in any way detailed, but hey, why actually watch the movies.
It's not shown, but fuck it, lets assume there are turns all the way down? Retarded

5. And of course, we only have your say so that the torpedoes couldn't make the necessary maneuvers to make it down the exhaust shaft if there had been turns.
My say is common sense, your say is fanboyism because you're butt hurt that someone in your beloved universe is a retard. A torpedo traveling that fast can't make tight turns in time.

6. And "dillhole"? wow

It was intentional? If Tarkin goes rogue you need a way to take care of him. Preferably after he has toasted some worlds.

Knowing Emperor, it could be.

Yes there is, it's in the novel. They found it insane. If you can't figure that Wedge's comment is meant to give voice to that dissatisfaction, then that's your own issue.

Garbage. Wedge is a combat flyer, Luke's a bush pilot with no combat experience whatsoever. Your subjective idea that he's a 'wuss' mean absolutely nothing as to the validity of what he was saying.

This is simply "ignore what the movie is clearly telegraphing to the audience" territory. I guess Obi-Wan was just exhorting Luke to turn off the targeting computer and use the force because he's an idiot?

Based on what? You've presented no evidence of this. All the evidence points in the exact opposite direction, in fact.


That's immaterial. You're trying to make out it's some sort of really obvious glaring weakness, and it just isn't. Your attempts to argue otherwise fly in the face of the entire movie.

Frankly, I don't care about the novel.

Just because he's a combat flier doesn't mean he's not pessimistic or a wuss. And that's bullshit about Luke, he's fucking superb, even Vader -the best pilot in the galaxy TM- is impressed.

What's the opposite direction exactly? That Luke guided the misseles by himself? My evidence that he didn't is the fact that he can't pull a lightsaber out of snow some time later, and you expect me to believe he guides those missiles? He obviously uses the force to tell him when to release pre-programmed torpedos, it can be nothing else.

Oh, yeah, it's impossible to monitor and diagnose a complex technological system because you say so.

*looks at computer in front of me*

OH WAIT! I hear 'engine fail' systems are incredibly basic 'trip sensor to start light' stuff, but that engine management computers are complex enough to control almost every function of the engine and output it to a logger. But it's impossible in the far future of FTL-science, EVEN THOUGH THE FALCON KNEW WHAT WAS WRONG. A simple text popup on a monitor would have communicated the information you stupidly assert is impossible to gather.

Ah, the good old far future FTL science argument, so it must be true.

No, not really. What is the Death Star made for? Overwhelming power projection and intimidation factors. What is a US Super Carrier for? Overwhelming power projection and intimidation. It's the reason every time the US has a major diplomatic situation where they need someone to back down, we park a carrier just outside their coastal waters or beyond range of any AShM's they may have. This still ignores the fact that you haven't shown how my analogy is incorrect.

What's the power ratio of super carrier to fighter, and death star to fighter? I don't care what their role is, death star is clearly in a different class to a carrier, you're analogy would only be correct if you were comparing a carrier to a star destoryer.

I love how ExarKun just ignored my reply which basically showed that the Rebels tried a massive starfighter attack of 500+ X-wings and a lucrehulk carrier against an unfinished DSI and still failed massively.

But clearly, after a demonstrated failure against an unfinished target, the Imps were supposed to give a lot of thought about the danger of starfighter attacks.

I didn't see your reply. When did that battle happen? Is that on Director's cut?

Nonsense. If you watch the scenes inside the Rebel base, it's quite obvious that they're nervous as hell. Why would they be nervous if they expected the X-Wing gambit to work reliably?

And if they had the choice to evacuate before the Death Star could blow up the planet, why the hell didn't they do it anyway and send the X-Wings in, instead of just sitting there while the Death Star moved into firing position? They already knew the Death Star had plenty of TIE fighters and shit, so they had to know that their plan might fail.

Even if you thought your X-Wing plan had a 99% chance of working or whatever, you'd have to be a complete fool to just sit there and do nothing instead of boarding a transport and commanding the battle from safely out of superlaser range.

It was hard to destroy with fighters; you will notice that fighters actually had to defy the laws of physics using a supernatural force to destroy it.

The Death Star was armored and shielded such that no conventional fighter attack could possibly have destroyed, or even seriously threatened it. All they could do was shoot up the surface. Only by having the exact blueprints, analyzing them carefully, and launching what they had to know was a suicide mission did they even get close to succeeding. Even then, they had to use magic.

Wait, what? Why is an amateur who thinks he can do it to be trusted over a professional who thinks his tools aren't up to it?

Why would a torpedo that can make one turn be unable to make several? That makes no sense.

They're nervous because it's battle time, and the odds are against them. No body goes into combat with a big smile on their face.

Your evacuation argument works for you and against you. May be transports needed longer time to prepare to leave. They could have, however, escaped on the fighters. If this mission was so impossible, why didn't they just evacuate on the fighters they had, as long as the leadership is alive, the Rebellion will stay alive. As long as ibn Laden is alive al qaida is alive, it doesn't matter how many low level terrorists US kills or training camps destroy. They had a choice:

1. Leave on those fighters and survive to fight another day
2. Fight with those fighters and win.
If it was 1 in a million chance, they would have picked option 1.

What laws of physics did fighters defy? They didn't know Luke could use the force, and they still went with option 1 from the above. They felt the computers can do it. Hard but they could do it in a few runs.

It doesn't matter if Luke is an amateur, he's a superb pilot as shown. I'd trust his opinion over Wedge.

That torpedo has a pretty wide angle of turn. If you put the zig zag patterns close together, they won't have enough time to turn when traveling at such speed, it's pretty simple.

Addendum:

Here is a cutaway taken from the main site's TL commentaries section:



Can anyone find the ICS cutaway of the Death Star (or is this also from the ICS?)? Squint and you'll see that this cutaway shows the shaft (to the upper left) going nowhere near the station's core, cutting through many decks at an angle. The reactor is above the equator of the station, roughly centered between the pole and the equator, so the shaft doesn't travel to the core itself. The shaft in the image shown here clearly conflicts with the simplified briefing room presentation.

The shaft is also obviously not within the equator, so that's either another shaft, or the diagram shown here is way off.

Is that a screen shot from the movie itself? I think I remember a scene where Dodona shows the torpedo flying down the shaft straight to the reactor.

[ExarKun]

You can play and adjust figures as you like. The turn we see the torps made is very wide, there is no way they could maneuver inside the shaft. It's till an insane error on the part of the designers

[Thanas]

I love how ExarKun just ignored my reply which basically showed that the Rebels tried a massive starfighter attack of 500+ X-wings and a lucrehulk carrier against an unfinished DSI and still failed massively.

But clearly, after a demonstrated failure against an unfinished target, the Imps were supposed to give a lot of thought about the danger of starfighter attacks.

I didn't see your reply. When did that battle happen? Is that on Director's cut?

I am not going to reply to the rest of your ramblings as I will not intrude on the pleasures of others, but the attack happened in 0 BBY, the same year the DS was finished. You can read about it here with further references.

In short, a rebel attack of hundreds of fighters failed against an unfinished DS. Clearly they were supposed to care about the possibilites of an attack made with a fraction of that strength...when an attack failed that utilized way stronger numbers.

[Stark]

So if the torpedo is supposed to make a 70,000g turn to ENTER the tube, and they have complete specs of the tube, why would corners stop it? Surely the weapon would be programmed to follow the required course, within it's ludicrous turning capability.

PS, on the scale of the flawed powerpoint presentation (ps, superlaser is not on equator = display is guide only) any kinks would be invisible, even IF the display had the resolution to show them. PS? It didn't.