Starfleet Jedi

Third parties please comment here so we can keep this neat.

Page One: Slower than light travel and tactical maneuver.

Sothis, if you would like to go first (and therefore introduce the next topic when we get to the next page), go ahead. Otherwise, I'll make the first post in around ~6 hours.

If you'd like to set anything out about the rules of evidence before you get started, post in the other thread and we'll talk about that.

I'll begin by setting forth what I think to be obvious.

In Star Wars, there are two different kinds of sublight drives - antigravity drives, and ion drives. Antigravity drives only work within a gravity well - inside the hyper limit, generally. Presumably they operate via a repulsing field of some kind, pushing back against a planet.

Ion drives are the giant glowing things we see on the back of Star Wars ships, e.g., as in the case of the Twin Ion Engine fighters of the Empire (TIEs). Ion drives operate by ejecting a small amount of high speed ionized gas; these ions are accelerated electromagnetically. An electron beam keeps the ship from accumulating too much charge.

The first kind is what's usually used for lifting off. Ion drives don't work very well in atmosphere. Apparently the antigravity drive can be used all the way to the hyper limit, meaning that if you have a cargo freighter, you don't actually need an ion drive.

But if you want to maneuver in deep space, you want ion engines - and to gauge by the performance of the Twin Ion Engine family of small craft, they are as good as you'll get in the Star Wars world.

Indications are that ion engines typically top out around 100 gravities of acceleration.

Similarly, we have both maneuvering thrusters and impulse drives in Star Trek. Maneuvering thrusters are for docking; impulse drives are for moving. Impulse drives are incredibly fast - in some cases, impulse drives seem FTL. They also do provide a large amount of realspace thrust when necessary. At top power, typical impulse drives pull on the order of thousands of gravities.

Most tellingly on the scale of in-system maneuver is that warp drive can also be used for slower than light travel, although it is rarely used in combat.

From this contrast, Star Trek ships clearly have an advantage in sublight speed - by a factor of ten to one - and they do so mostly because they use a drive system whose physics are more questionable.

Hello there :O) sorry for not posting sooner, but my access to the computer is somewhat limited at the moment.

I'll start with the obvious about Imperial starship speeds- ROTJ demonstrates impressive straight-line speed for Star Destroyers- they had to move quickly from behind Endor (where they had been hiding out of sight) to swing round and then trap the Rebel fleet. To move around the moon like that is to cover thousands of miles in a matter of seconds- to do otherwise is to lose the element of surprise and risk the Rebels escaping.

Fighters are extremely fast, able to cover a 400,000KM distance in five minutes, placing their acceleration in the region of 17,000 m/s. Star Destroyers can't match this- assuming Endor to be earth-sized (12,000 miles in diameter), and giving the Imperial ships 30 seconds to move around the moon to trap the Rebel fleet, we're looking at a few thousand m/s- several thousand m/s slower than a fighter, which is to be expected, given what we see in ROTJ.

The TNG TM states that impulse engines are capable of 0.75c, but this is rarely seen- a look at DS9 episodes like 'Sacrifice of Angels' or 'Tears of the Prophets' gives us relative speeds that are a lot slower. The acceleration of Federation ships appears to be in the region of between 10,000 and 15,000 m/s, making them nearly as fast as a fighter, but not quite. This would make them faster than Imperial capships, but such speeds are rarely seen in combat situations, bringing up the question of why. That is something only Captain Picard et all can answer :o)

Sothis wrote:Hello there :O) sorry for not posting sooner, but my access to the computer is somewhat limited at the moment.

I'll start with the obvious about Imperial starship speeds- ROTJ demonstrates impressive straight-line speed for Star Destroyers- they had to move quickly from behind Endor (where they had been hiding out of sight) to swing round and then trap the Rebel fleet. To move around the moon like that is to cover thousands of miles in a matter of seconds- to do otherwise is to lose the element of surprise and risk the Rebels escaping.

Can you quantify this more precisely? I am of the opinion that the ROTJ sequence is both highly imprecise and open to widely variant interpretations, and thus no good for creating any solid estimate of acceleration.

Fighters are extremely fast, able to cover a 400,000KM distance in five minutes, placing their acceleration in the region of 17,000 m/s.

Both the time and the distance are incorrect.

First, time. Before the Rebels launch fighters, the Death Star has an ETA of 20 minutes; after, 15 minutes. The Rebel fighters begin attacking shortly before the seven minute mark is read off. It is therefore more accurate to estimate that it took somewhere between 7 (15 minute ETA -7 minute ETA - a minute of the Rebels' initial attack) and 13 (20 minute ETA - 7 minute ETA) minutes, i.e., 10+/-3 minutes.

Second, the Death Star will be in firing position as soon as it has line of sight. Given that the Death Star is orbiting approximately one half Yavin's radius away from the surface of Yavin, and Yavin IV roughly a full extra radius, we can see the Death Star doesn't have a clear line of sight until it's within three times the radius of Yavin:


Given that Yavin is a gas giant, we may take its radius to be most likely 50,000 +/- 25,000 km (i.e., between Neptune and Jupiter in size), which puts our distance as 150,000 +/- 75,000 kilometers.

Now, noting that for a high speed intercept, x=at^2/2, the Rebel fighters can reach the point at which the Death Star can fire using an acceleration of 830+/-650 m/s^2, or 85+/-66 g. If the Rebel fighters are to also match the Death Star's velocity at that point (about 100 km/s towards Endor), this increases their acceleration by a factor of around 130% (plus ~ four thirds), giving them 200+/-160 g.

However, that's not all; we also know that the Millenium Falcon, after traveling some distance from Tatooine, still needed "several minutes" to reach the hyper limit. Based on the fact that several minutes remained, we could ballpark the trip at 5-10 minutes (7.5+/-2.5) in length; based on the fact that the hyper limit appears to be no further than 6 planetary diameters for a typical planet, this gives us a distance of 75,000 km, which means an acceleration of around 76 gravities. Even taking the low end of this range (5 minutes) barely pushes us to 160 gravities of linear acceleration.

The TNG TM states that impulse engines are capable of 0.75c, but this is rarely seen- a look at DS9 episodes like 'Sacrifice of Angels' or 'Tears of the Prophets' gives us relative speeds that are a lot slower. The acceleration of Federation ships appears to be in the region of between 10,000 and 15,000 m/s, making them nearly as fast as a fighter, but not quite. This would make them faster than Imperial capships, but such speeds are rarely seen in combat situations, bringing up the question of why. That is something only Captain Picard et all can answer :o)

Relative speed is the key term here. Combat maneuver is an entirely different problem than raw speed for Star Trek, quite probably because of the use of subspace fields.

Maneuvering is indeed another matter. See, for example, "Sacrifice of Angels."

The Defiant makes short controlled evasive yaws about as quickly as the X-Wings in the battle of Yavin - call it about 45 degrees in a second - during most of its maneuvers. The Defiant, Birds of Prey, Starfleet's rare fighters, Cardassian Hidekis, and Jem'Hadar attack ships have maneuverability sharply superior to larger ships. In "The First Duty," we learn that small single-pilot craft can pull a tight circling maneuver at 80,000 kph, which confirms the notion that small Federation craft are every bit as maneuverable as we expect.

The Falcon can flip on its side in one second (90 degree yaw), and when Lando orders all craft to pull up in the battle of Endor, it takes about two seconds for an X-Wing to swivel its path 90 degrees. (See, for example, 1:50-1:52). Every now and then we can see a fighter execute something like a snap turn (e.g., as they enter the Death Star), popping 90 degrees at several hundred m/s in a turning radius of only a hundred meters or so.

It's fairly impressive. Quite possibly, smaller SW fighters can turn slightly faster than ~100m Trek ships, but all told, they're similar enough in agility to be competitive with one another on that account.

A Galaxy class, the largest ship in Starfleet, turns a bit slower than the fighters or its smaller counterpart. See 6:12 to 6:16 - it takes about 4 seconds to swivel 90 degrees.

This is much faster than the maneuvers seen by Star Wars capital ships, which only seem to change direction by several degrees per second. Even in the Executor's sharp uncontrolled dive towards the Death Star, it isn't swiveling at more than 10 degrees per second (see 6:43-6:48), and that's exceptionally swift turning for a Star Destroyer. I can't think of a single controlled turn by a SW capital ship at more than 5 degrees per second, even in the near collision in the Hoth asteroid field.

Accordingly, we can expect small craft to have fairly similar maneuverability, but in regards to capital ships, the largest ships Starfleet has to offer can (and will) pivot over twice as fast as any in Star Wars that isn't a fighter - most likely, we'll see Starfleet's ships pivot ten times as fast.

Returning to the speed of Star Trek ships, as you have placed the acceleration of ST ships at 1,000-1,500 g, this is not so far from the 1,000-10,000g I suggested, and so I leave resolving the detail of the upper bound for a later post.

Hello again.

Sorry for taking so long to reply. Things have been quite busy here, but I have a free moment, so provided the computer plays ball, here we go.

Regarding the acceleration of fighters and the distance mentioned, I'll quote from SD.net, though I can't include the pictures in the quotes, so I'll also link to the page in question regarding that.

ANH: Battle of Yavin

X-wing starfighters easily traversed a 400,000km distance in less than five minutes before the Battle of Yavin, suggesting accelerative capabilities on the order of at least 17,000 m/s² (1700 g's). The DS1, easily the slowest vessel in the fleet, circumnavigated partway around the 200,000km diameter gas giant Yavin in 5 minutes, as seen in the following screenshots of the Rebel display console at Yavin:

The pictures themselves are at the start of the page: http://stardestroyer.net/Empire/Tech/Pr ... sion2.html

Nevertheless, a time frame of seven minutes for the fighters to reach the Death Star still points to an acceleration of over 10,000 m/s, which is still significantly above the combat speeds seen on Star Trek, so going by your seven minute time frame, not a lot would change.

At 13 minutes to reach the Death Star, the acceleration would decrease further, but I will not even attempt to work out precisely what it would be, except that it would fall below the 10,000 m/s mark. It would still be considerable though, on a par with the raw speed of Federation vessels- although, as mentioned before, the combat speeds of Federation ships are rarely as fast as their top speeds, which is where the speed- and agility- of the fighters comes in.

I would also like to quote from Curtis Saxton's site for a moment, regarding the speed of Star Destroyers:

The moments before the Battle of Endor provide one of the best demonstrations of accelerative capabilities. The tactical screen in the power generator bunker shows the fleet of star destroyers moving into position near the Death Star II in order to trap the rebel aramada which is due to arrive. This shot lasts for 94 movie frames, about 3.92s. Scaling by the horizontal diameter of the DS2 (106 pixels in laserdisk, assumed to be 900km), the horizontal interval between the screen's vertical lines is about 97km (183 pixels for 16 intervals). The destroyers cross 189km in 92 frames, implying a mean velocity of 49 km/s in the plane of the screen. The true velocity could be greater if there is a component of motion perpendicular to the plane of the screen. This speed may be further underestimated because of the dead-time between screen updates: refreshes of ship positions occur about once per second, and one was due at about the time when the movie scene was cut. At this speed and heading, the fleet could have hit the surface of the battle station within several seconds. The destroyers must halted within this time. This implies a minimum deceleration on the order of a thousand G (depending on the unknown velocity component and geometry in the perpendicular direction). The true deceleration is most likely a few thousand G.

A minimum deceleration of 1000g places a Star Destroyer's accelerative abilities in the same region as the low-end for Federation vessels. It is possible, as Mr Saxton concedes, that the figure is even higher, though it depends on what he means by 'few'.

It must also be noted that in ANH and in TESB, Star Destroyers were able to match the straight-line speed of the Falcon. It's worth noting that the Rebel capships in ROTJ were right behind their fighters when the fighters began their evasive action to avoid smearing themselves on the shield- further evidence of impressive capship speed.

Federation capships are more maneuverable than their Imperial counterparts, and I'm willing to concede that they may be slightly faster, but even the likes of the Defiant have never demonstrated the tight turns and maneuvers of the fighters in ROTJ. When they swoop into the DS2's port to begin their attack on the core, the fighters match the Falcon's maneuver- the Defiant would not be able to achieve such a turn.

In short, I feel we can end this particular debate right now. I am happy to concede that Federation capships are more agile than their Imperial counterparts, and I am even happy to concede a speed advantage to Federation ships. The issue is whether this would be relevant in a fire fight, which I feel I can argue successfully that it wouldn't be of any help. That is perhaps an argument for another debate.

Sothis wrote:The pictures themselves are at the start of the page:

Those pictures are the same ones I used to reach my distance figures.

A minimum deceleration of 1000g places a Star Destroyer's accelerative abilities in the same region as the low-end for Federation vessels. It is possible, as Mr Saxton concedes, that the figure is even higher, though it depends on what he means by 'few'.

There are two problems with Saxton's figures. First, he is assuming that the Star Destroyers were on a collision course with the Death Star. While he acknowledges that there could easily have been lateral velocity as well perpendicular to the direction of the screen, he does not seem to realize that means a collision is entirely unnecessary.

Second, he is assuming a 900 kilometer wide Death Star displayed to scale on the diagram, something that inflates his figure substantially.

It must also be noted that in ANH and in TESB, Star Destroyers were able to match the straight-line speed of the Falcon.

Which, in ANH and TESB, is established as being very far below 1,000g. In ANH, for example, the median estimate is ~80g for the Falcon.

It's worth noting that the Rebel capships in ROTJ were right behind their fighters when the fighters began their evasive action to avoid smearing themselves on the shield- further evidence of impressive capship speed.

Raw linear acceleration is pretty similar between fighters and capital ships.

Federation capships are more maneuverable than their Imperial counterparts, and I'm willing to concede that they may be slightly faster, but even the likes of the Defiant have never demonstrated the tight turns and maneuvers of the fighters in ROTJ.

When they swoop into the DS2's port to begin their attack on the core, the fighters match the Falcon's maneuver- the Defiant would not be able to achieve such a turn.

IMO, the Defiant has demonstrated the ability to turn half as fast as those most agile fighters - but at its larger size and generally higher flight speed, that is a much larger turning radius.

In short, I feel we can end this particular debate right now. I am happy to concede that Federation capships are more agile than their Imperial counterparts, and I am even happy to concede a speed advantage to Federation ships. The issue is whether this would be relevant in a fire fight, which I feel I can argue successfully that it wouldn't be of any help. That is perhaps an argument for another debate.

Very well. I would be happy to continue it, but if you're perfectly willing to concede substantial advantages in agility and acceleration to Federation capital ships over Star Wars capital ships, we should move on. Pick the next topic, then.