Gentlemen
I was consolidating these thoughts for a dedicated thread on the subject, but since the topic has come out... I figured out how to derive the theoretical maximum hyperdrive range for a ship.
The key bit was reading
The Steele Chronicles. There is a line in there about how TIEs use matter-to-energy conversion in their microparticle accelerators to ensure they never run out of fuel. Obviously that sentence doesn't make sense. But then I got thinking, that for the powers we are talking for these craft, nothing precludes them from using e-mc^2 to make reaction mass "on the fly". Given that relativity allows one to raise any given mass to any arbitrary mass through sufficient acceleration, a light stream of subatomic particles could suffice. This would also explain why all the starships we've seen only display
one type of
fuel tank. If all they are carrying is hypermatter, then that would make sense.
If there is only one kind of fuel mass being carried then, we can place a theoretical upperlimit on the amount of fuel carried (and thus reactor EFPH - effective full power hours) as the mass of the ship (with EFPH being the mass-energy of the ship divided by the power of the reactor; convert to hours). If you know the fully fueled mass of the ship, you can figure out how much mass is consumed in a trip.
Now we also have this
Dark Force Rising, pg. 212 hardcover wrote:
"From the labored sound of the engines, [Mara Jade] could guess they were pushing uncomfortably far past a Victory Star Destroyer's normal flank speed of Point Four Five. Possibly even as high as Point Five, which would mean they were covering a hundred twenty-seven light-years per hour."
Now Mara doesn't know where they are going, or the local routes, or the calculations used. These are things that create the wildly varying speeds hyperdrives are capable of. That she doesn't know and still estimates indicates that she is using the industry standard or baseline or whatever. That a hyperdrive rated with a "solo factor" (since we don't know the real name of the number) of 0.5 can do 127 ly/hr.
Now to correct that is fairly simple. As a basic rule, hyperdrive velocity appears to follow v=h/sf where v is velocity, h is hyperdrive standard speed, and sf is the afore mentioned "Solo Factor" Using this, the industry standard is 63.5 ly/hr
Now since we know the range of a number of these craft, and their velocity, time is easily derived. Fuel divided time indicates the fuel efficiency of the craft, at this point I converted things over to energy and found power just to help me keep the units and numbers straight. We get the following
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Venator Rescusent Munificient Acclamator H type J type ARC-170 P-38
Mass 4e11 9e10 3e10 2e10 8e5 4e5 1e5 5.75e4
Range 60000 30000 150000 250000 20000 80000 5000 3000
SF 1 2 1 0.6 0.9 0.7 1.5 2
H 63.5 63.5 63.5 63.5 63.5 63.5 63.5 63.5
V 63.5 31.75 63.5 105.83 70.56 90.71 42.33 31.75
Hours 944.88 944.88 2362.2 2362.2 283.46 881.89 118.11 94.49
Seconds 3401574.8 3401574.8 8503937.01 8503937.01 1020472.44 3174803.15 425196.85 3041574.8
kg/s 117592.59 26458.33 3527.78 2351.85 0.78 0.13 0.24 0.17
watts 1.06e22 2.38e21 3.18e20 2.12e20 7.06e16 1.13e16 2.12e16 1.52e16
watts/kg 2.65e10 2.65e10 1.06e10 1.06e10 8.82e10 2.83e10 2.12e11 2.65e11
As you can see there is a rough trend of at least the order of magnitude indicating a certain level of power required per unit mass of the ship to remain in hyperspace. That this is related to the mass has a problem in that the mass of the ship is decreasing as it goes, so I believe it is actually related to volume (which mass is proportional too), but I don't have the figures to verify that. Anyhow, while we have a general OOM trend, we have outliers among the smaller craft. Further, this doesn't make much sense in the context of basic design or things like the hyperdrive rings - it doesn't take into account that certain ships are going to be packing additional fuel. And the initial assessment was for 100% fuel, which the craft aren't.
This time around, we take the Ships mass and multiply it by the watts/kg factor from above. I went with 1e10 w/kg to get the OOM consistency. This gives us the power required to operate the hyperdrive. E=mc^2 gives us the fuel they consume each second. We repeat the earlier process of getting the "in flight" time and multiply that (in seconds) with the rate of fuel consumption to get the fuel mass. If we divide that by the ships total mass, we find out what percentage of the ship is fuel.
I'm not going to code all the figures again, but here is a list of the final values
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Fuel fraction
Venator 0.38
Recusant 0.38
Munificent 0.94
Acclamator 0.94
H type 0.11
J type 0.35
ARC-170 0.05
P-38 0.04
Testing with other values for the w/kg figure, only 1e10 really works without producing oddities (eg the Acclamator needing to mass nearly 2x its total mass). So that figure is "good enough" for now, though I need to figure out where it comes from (again, I presume it is volume related but can't check at this time)
Also unknown is where the fraction of the ships mass that is fuel comes from. Is it by measuring the size of the tanks in images and comparing that to the overall volume? A figure derived from other traits I haven't noticed yet? An estimate that results from a chain of thought? An arbitrary figure handed down by George Lucas? Unknown. I expect that it is the result of a rational argument, note that the ships meant for transport (troops and cargo) have very high mass fractions, that those with a great deal of empty space in their hulls are sitting at about 40%, and the fighters are at single digit percentages. It also varies with those close in size having similar figures. I expect the fact that the numbers do not match perfectly or fall within even values is the result of rounding and estimate errors on my part, and they should be more smooth. This is deserving of more study in the future. For now however, it also answers the question of why most fighters don't have hyperdrives. As they are so small they have a very limited fuel capacity, particularly in relation to their overall mass. They thus cannot carry enough fuel to sustain hyperdrive flight, even if they had a hyperdrive installed. The mass of all the extra fuel is more likely to be the "extra mass" that designers seek to shed rather than the hyperdrive itself.
In any event, using what we have, we can then derive stats for other craft, provided we have their hyperdrive rating and know roughly their mass. Even if we don't know the Fuel fraction, we can set an upper limit on range by assuming 100%. Doing this, the ISD is capped at 160k light years, the Providence class at 100k, and the Nebulon-B and Dreadnaught at 80k. I personally expect that the Dreadnaught is more limited due to a lower fuel fraction, it being designed in the age of in-sector flights. And I'd expect the ISD to be something closer to 80k.
Questions for the future:
* Why 1e10 w/kg? Investigate if this is related to volume, and then discover source of that figure.
* Why a constant power draw? In hyperspace a ship should behave IAW the laws of motion. Perhaps this draw represents the power consumed by the "shift shields" of the ANH novel or the stasis fields that control flow of time while FTL. When those can no longer be powered, the ship needs to leave hyperspace or else be stuck in that state forever.
* Why those fuel fractions for those ships? What was the line of reasoning to determine those figures, and extrapolate it to other craft.
In relation to the topic of the thread, it is interesting to note that this system does provide something of a practical upper limit on the range of the ship. Even if the ship is 100% fuel you need a hyperdrive with a better rating to achieve anything like what you would need for intergalactic distances. 0.5 is noted as being abnormally low, and 0.4 (for the Jabitha) is exceptional. Yet to hit the ~4e6 ly one would need a hyperdrive with a rating of
0.04. And that is for a ship with 100% fuel. Thus we have a rationalization for a more absurd bit of EU, there is
effectively an unpassable barrier around the galaxy - no ones ship can go that far. They actually do, in effect, "fall off the edge of the world". There are additional concerns as well. Such a low hyperdrive rating will mean the ship goes much faster. This means that collisions with interstellar dust will happen at a far greater rate, threatening the ship, perhaps past its sustainable point. This is a threat in the galaxy as well. The original ICS makes mention in its Millennium Falcon entry that Solo's hyperdrive generates a field with an exceptionally small cross section. In practical terms, this would mean that its "shift shield" deflectors minimize what they will hit, allowing the ship to go faster without risking being destroyed. This also leads us to a possible reason as to why Jedi were needed to "find a way through the barrier". Using the Force they could see a path that was optimal for the ships so they would not be destroyed, much as force sensitive explorers did in the early days of the Republic.
Yeah, that's a lot of words. You should still read them all if you want a technical talk of hyperdrive range and Outbound flight.
