Star Wars Fuel and Densities

No, this is not a comprehensive post . . . just a note from the TCW novelization, Ch. 16 and 17, which is when the newly-acquired Twilight, no longer trying to get aboard the Republic Attack Cruiser within Teth's atmosphere, is instead going to try to make it on her own.

Ch. 16:  Even at maximum thrust, the Twilight climbed slowly for a pilot used to starfighters. [...] The freighter shuddered as it climbed. [...] He tweaked the fuel injectors a little higher.

Ch. 17:  "I can't outrun them," he said. [...]
"Let's jettison something," Ahsoka said at last.
Laser cannonfire streaked past the Twilight's nose, and another vulture droid buzzed the ship, so close to the cockpit viewport that Anakin jerked hard to starboard in pure reflex.[...]
"What?  Can't dump fuel."  Anakin checked the gauges.  "It's not like it weighs enough to make a difference,and we've got to get to Tatooine."
"Water," she said.  "Ballast."
"I didn't check the cargo bay."
"I'll do it," she said, and before he could stop her, she'd strapped Rotta in the copilot's seat and was making her way aft. "I jettison whatever I find, right?"
"Yeah.  When you open the cargo hatch, I'll get a red warning light up here, and I'll just bring up the nose and let everything slide out.  Don't waste time dragging any crates up to the tail ramp."[...]
The cockpit intercom buzzed.  "Master, I'm in the cargo bay now."
"Good.  What do you see?"
"Plenty of crates, and the reserve water tanks are showing full.  That's five tons at least."
"That might do it.  Open the drains on the tanks and make sure you're standing behind anything heavy that's going to slide out the back when you hit the big red button." [...]
"The console warning light flashed to life:  CARGO HATCH OPEN. Anakin brought up the nose and the Twilight climbed steeply.
He thought he heard Ahsoka say something, but it was drowned out by the noise of air buffeting the bay.  The freighter soared.  Suddenly there were no vultures ahead of him, and he was heading into darker skies as the ship climbed. 

There's a lot of interesting information here.

1.  Five tons, plus some unremarkable and presumably-draggable crates, are sufficient to significantly alter the performance of the Twilight and allow it to escape vulture droids, climbing to orbit over the course of the next page or so until it could make the jump to hyperspace after clearing the atmosphere.

The Twilight's volume is about 4,600 cubic meters, and per our recent ruminations on the density of the engine section of Star Wars vessels, we presumably have good confirmation that her mass might be somewhere in the range of 2300 to 4600 tonnes.   And yet, five stated tonnes plus some unremarkable crates is sufficient to offload enough mass to make the ship, whose performance had been less than starfighter-ish previously, to soar and leave starfighters in its dust.

Perhaps our estimates of the mass are thus too high for this ship.

After all, consider that the performance went from slow to starfighters-suck.   The jettisoned mass would thus have to constitute a very significant portion of the ship's entire mass.  If a total of 100 tons were jettisoned in this circumstance, for instance, I would expect the total ship's mass be no more than 1000 tons . . . probably less.

(And you know, it makes some sense that an empty freighter would be a speed machine, though it's still odd a starfighter would lose to it.  Unlike modern vehicles where you have to gear for certain performance preferences (towing requiring a completely different setup than high speed), a spaceship would not really have these concerns assuming the same basic thrust-generating technology was in use for a starfighter versus a freighter.  Thus, a freighter would be designed with supreme engines simply in order to move the loaded bulk, but unloaded she'd be a high power-to-weight speed machine.)

2.  Anakin notes that the fuel doesn't weigh enough to make a difference.  But, he thinks five tons of water and some crates will.

Understand, even if the ship was carrying a full load of crates full of solid lead, it's irrelevant because Anakin's mental calculation was in regards to crates that Ahsoka could drag.  Thus the mass and density of the crates in his mind would've been on par with the crates we see two clones always teaming up to carry around on Republic cruisers.

It thus seems unlikely that he would've been expecting even, say, another five tons of cargo.  Thus, the total amount he expected to offload ought not have been more than ten tons or so.

Around ten tons of cargo thus outweighed the fuel on the Twilight, significantly enough to be in the "might do it" category versus the "won't make a difference" category.

2A.  Also note that he references the need to get to Tatooine in reference to fuel jettison.  And we know Teth and Tatooine aren't too far from one another insofar as the duration of the trip.

a.  Let's say the ship had a full load of fuel.  How much would be needed to reach Tatooine?  If it's 1% of the ship's fuel, then 99% of the fuel weighs a lot less than ten tons.   If it's 50% of the fuel, then 50% weighs a lot less than ten tons.   If it's 75% of the fuel, then 25% weighs a lot less than ten tons.  And so on.

b.  It's also possible that he checked the gauges and saw that the ship barely had enough to get to Tatooine.  In that case, it required much less than five or ten tons of fuel to get there.  At rough maximum, then, given that set of parameters and that it didn't weigh enough to make a difference, the ship was going through a very small weight of fuel in order to make orbit and make the jump to hyperdrive to get to Tatooine, not to mention deorbit and landing.

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Suffice it to say, it looks like our vessel mass is too high in the case of the Twilight from this example, and moreover we now have confirmation that Star Wars fuel is not very dense in the canon . . . not that we didn't already know that from RotS and the watery fuel scenes (deleted in the film but still present in the script, for instance).   However, it's nice to have another confirmation.

Contrast this with Star Wars inflationists who insist that Star Wars fuel is hyperdense magic material . . . and of course contrast the five tons making a performance difference with their claims of Star Wars vessels having densities many times that of water.  Such 'fanatics' (to borrow a phrase) can point to whatever they like . . . the canon is what it is, even if they don't understand how it works from their certain point of view.

Sinking Ships, Pt. II

Following on from the last post . . . what would we expect of a Star Trek starship?

Well, the Constitution Class ship, if gingerly placed upon water and then released, would sink immediately.  That's because the vessel's density is over four times greater than water, even including the hollows aboard.  It would thus behave rather similarly to a dense rock, because, overall, that's the density she is.

I have no idea about the drag coefficient of the venerable Connie, and wouldn't be interested in hazarding a guess.  I went and looked at this site where they do a wind tunnel test of a refit Constitution in the form of that crappy TMP-era toy that they re-released for Star Trek V.   But, while I'm tickled pink at finally having a good excuse to link to that (had that one up my sleeve about ten years now), I'm sad to say they didn't provide any estimate of the drag coefficient.

An Intrepid Class ship would do about the same, but might sink somewhat less quickly, as her density is only somewhat above that of water.  In any case, her frontal area is going to be significantly larger, and while her drag coefficient should be superior to the Constitution Class in some areas, they both suffer from the navigational deflector effect on drag.

I have no idea what would happen with the saucer section . . . would it hold up the saucer for a moment and make the ship sink tail first?   Probably, especially if the nacelles are very dense.

But while writing this, something finally dawned on me.   Klingon ships . . . at least the small Bird of Prey . . . may be rather on the light side of the spectrum.

See, though I've pondered the notion of a historical trend in regards to starship masses, it may simply be that the Intrepid Class was designed to land intentionally . . . after all, unless you make a big flat bottom, it's hard to land a Constitution Class weighing in at over 900,000 tonnes.   Little landing legs just won't do.   Even Voyager's legs shouldn't be able to work . . . the ground pressure would be enormous.

This brings me to Kirk's comment about the crashed Bird of Prey in ST4 . . . he says something about getting the whales out "before we sink", and had just ordered the bridge hatch blown upon finding out they were in the water.   Kirk had no idea where the ship was . . . deep ocean, lake, river, et cetera . . . so unless he did some quick math about the fact that he didn't hear water all around the bridge yet, or didn't feel that the ship was turned ass-down, or if he felt the thud of the hind end hitting the bottom of the shallow San Francisco bay (whose depth is measured in low-double-digit feet), it might seem odd for him to order the hatch blown.

As noted in the last post, ships float because while the density of their parts is greater than water, the density of their parts all spread out along a large hull with lots of empty space inside isn't.  But any ship whose total density is greater than that of water is going down pretty fast.   That makes Kirk's comment odd, because if he was used to extremely sinkable ships, then the notion of a Bird of Prey lasting any length of time would be very odd, and ordering the hatch blown would have been a death sentence.

After all, if the Bird of Prey was as dense as his Enterprise, blowing the hatch would just fill the bridge with water.   The crew would've had to live long enough for the water to fill the bridge and then escape . . . which is actually pretty plausible, except for the fact that by the time that happened they could be literally hundreds of meters below the surface of the ocean or whatever they were on (as far as Kirk presumably knew) assuming they dropped like a 50lb solid steel sphere.

This suggests that he had information of some kind . . . either that the tail end was down on something (at least temporarily) and the front end might drop down, or that the particular class of Klingon Bird of Prey he was riding on was actually less dense than he was used to, and maybe even less dense than water.

Another alternative, of course, is that Kirk is an idiot, and Spock too for not correcting him.   Trek-haters would default to that, but that's not the style here.

In any case, the evidence for less dense Birds of Prey is somewhat flimsy, but there it is.   Perhaps one could do a ground pressure estimate based on the landing in the park in ST4, but I don't know how well that would work.  After all, Voyager's ground pressure figures don't work, either.

In any case, we have one other sinking event, that being the Jem'Hadar ship in "Rocks and Shoals"[DSN].

That ship lasted long enough to let everyone get out and get to shore with a little raft, which could suggest that it was a floater and thus that the bugs are less dense than water.   However, that's less than clear, because the ship is, as seen in the picture, extremely close to shore.   It might be like San Francisco Bay, a Great Lake, or any other such thing . . . the ship could be sinking only into water or it might be burrowing into murky muck at that angle, a la quicksand, or falling off of a shelf.   There's no way to tell.

Sinking Ships

I've found on another site evidence of some confusion in regards to what starships should do in water.

A modern oceangoing ship floats because, although her hull and superstructure materials are denser than water, the ship is largely hollow and thus filled with air.  Gore a hole in the ship and allow it to fill with water, and the ship will sink.

This is, of course, what happened to the Titanic.  Her hull was scraped along 220+ feet of her side, with an estimated opening of 12 square feet in "a series of bent plates, split seams and small holes" to quote another site.   That's only 1.1 square meters of opening spread across 67 meters of the hull, which is why the ship took a good long while to fill with water and finally sink.

Notable is that despite becoming a water-heavy husk of steel, the ship still only cut through the water downward at 16km/h, or about 4.4 meters per second.

It's actually possible to work this out mathematically, as well.   Much as I did recently with the Type-6 shuttlecraft terminal velocity, it is just as easy to figure out the terminal velocity in water.

So what we need is the the square root of ((2*m*g)/(ρ*A*C)).   Our result will be the velocity.  The "m" is the falling object's mass, "g" is gravitational acceleration, ρ is the density of the medium through which the object falls (air or water), "A" is the frontal area, and "C" is the drag coefficient.

 Now, I don't have the first clue as to the drag coefficient of the Titanic or the mass of her halves, so for the moment I'm going to skip re-doing that math.

However, the reason this is so exciting is that we can do some estimates from "Gungan Attack"[TCW4].

In that episode, a small Republic cruiser of the type seen in TPM and "Jedi Crash"[TCW1]  is exploded to bits just above the surface of the ocean of Mon Calamari.  One of her three engines is propelled up and away from the rest of the ball of debris and, like the rest, falls into the water.  

This engine becomes the ride down to the bottom of the sea for our heroes as they grab hold of it.   We get to see it pass Ahsoka, who we will presume to be 1.5 meters tall.   At a framerate of a hair under 30fps, it takes about 10 frames for the leading edge of the engine to pass her up as she remains relatively stationary.   This implies a velocity of 4.5 meters per second . . . we'll round up to 5 meters per second for ease.  (A smoking feature passes her by shortly thereafter and only takes about eight frames, but by that time she's moving upward, swimming at it to grab onto it.)

The engine had almost certainly reached its terminal velocity at that time, since it had been in the water for thirty seconds by that point.  So, we have the result to the equation. 

But, that means we can find out other details, which will be sufficient to learn something even if we're just rocking the proverbial backside of an envelope here.

To review what we covered thirty seconds ago (for those of you in Washington, D.C.), that result of five meters per second is the the square root of ((2*m*g)/(ρ*A*C)).   The "m" is the falling object's mass, "g" is gravitational acceleration, "ρ" is the density of the medium through which the object falls (air or water), "A" is the frontal area, and "C" is the drag coefficient.

So, let's say we want to find the engine's mass.   All we need, then, is the gravity on Mon Calamari, the density of their ocean water, the frontal area of the falling cylindrical engine, and a drag coeffcient for it.

"C", the drag coefficient, is relatively easy in this case.  The engine is cylindrical, and per this site and very helpful graphs thereon, a cylinder that's less than twice as long as its diameter will have a drag coefficient above 0.81 . . . the graph itself suggests a figure of 0.88 or so.   Unlike a cylinder where the face and side meets at a 90 degree angle, however, the engine has more rounded corners, which drives the figure downward.  For instance, one simple shape, a slightly squashed sphere with the wide bottom taking the wind, has a drag coefficient of 0.59, and a rounded hemisphere (a la the front of the Y-Wing's engines) 0.42.   Of course, it also has little widgets on it and, in this case, a few person-sized holes, so that drives the figure back up.  I figure the drag coefficient ought to be somewhere between 0.75 to 0.88, so we'll go with 0.85 as a somewhat round and reasonable figure. 

"A", the frontal area, is also relatively easy to figure.   Based on schematics from Wookieepedia that look fairly accurate, and assuming the 115m figure for the vessel's length is about right, the starboard engine ought to be about 16.5 meters in diameter.  That equates to a frontal area of about 214 square meters.

(For those curious, that diameter equates to an engine length of about 20.6 meters.  As a result, we can confirm our velocity figure . . . the engine should take about four seconds to pass a single point when we see it fall by Ahsoka, and indeed it does.)

"ρ", the density of the medium through which the engine falls, could vary somewhat from normal water, but our safest assumption here is 1000 kg/m^3.

"g" is gravity, and again our safest assumption is one g, or 9.8m/s^2.

"m", for mass, is the figure we actually want to find . . . we already know the velocity is five meters per second.

So, shall we begin?   I'll try to show my work a little better this time:

5m/s = sqrt ((2*m kg*9.8m/s^2)/(1000kg/m^3*214m^2*0.85))
5m/s = sqrt ((m kg*19.6m/s^2)/(181900kg/m))

Truth be told, I hate the whole dividing fractions thing.  But this is the part where you can basically flip the bottom fraction and multiply, and your units start cancelling, to put it in layman's terms, to the following:

5m/s = sqrt (m*0.00010775151181968114m^2/s^2)

Now we'll square both sides for ease:

25m^2/s^2 = m*0.00010775151181968114m^2/s^2
m=25m^2/s^2/0.00010775151181968114m^2/s^2
m=232015.30612244898709682164

So, the mass of that part of the ship ought to be about 232000 kilograms, or 232 metric tonnes, give or take.

But, there's a corrective measure we need to consider here.  In air there's not a whole lot of buoyancy to consider, but in water, one should.   If we had the mass and wanted to determine a terminal velocity, we would simply "massage" the mass by subtracting the mass of the water that the item would displace.  However, since we're doing things bass-ackwards, we have to take the 232,000 kilograms as a pre-corrected value.

That said, however, we're playing around a few unknowns here.  As noted, the engine had some man-sized holes in it and these were seen to be full of water as the engine sank.  How much of the internal volume of the engine was hollow and filled with water?   We don't know.  If half the engine was empty space, for instance, our displacement figure would be way off.

Now the question is about the volume, though, so we can at least start making guesses about the water displacement.  It'll take a bit longer than I have at the moment to go into Sketchup and cut off that part of the ship and really do it right, but we can guesstimate for now.

As noted, the engine diameter was 16.5 meters, and the length was 20.6 meters.   Assuming a proper cylinder of those dimensions gives us a volume of pi*(8.25^2)*20.6, or about 4400m^3.   But, that's a bit too large given the rounded-off edges of the cylinder.  I'd ballpark the correct figure at closer to a cylinder of 13.9 meters diameter, which gives us a volume of pi*(6.95^2)*20.6, or 3125m^3.   We'll just call it 3500m^3 for now.

3500 cubic meters of water masses 3500000 kilograms.  That means we need to add that or some fraction of that to our 232000 kg to get the complete picture.   Assuming a perfectly un-holed watertight engine, for instance, we'd be looking at 3732000 corrected kilograms.   If half the engine was waterlogged, we'd be looking at 1982000 corrected kilograms.

So, basically, we're looking at engine density of 1982000/3500 kg/m^3 or 3732000/3500 kg/m^3, which work out to engine densities of 566 and 1066 kg/m^3, respectively.

That's pretty amazing, since I had previously estimated that "Star Destroyer density probably falls somewhere in the 500-1000kg/m³ range".   And here we have figures that are almost exactly that after a chain of math and reasoning.  

But, the fact is, the displacement correction in which I used half-water and no-water meant it couldn't have had any other result, because the 232 tonnes was such a small figure by itself compared to the 3,500 tonnes of 3500 cubic meters of water.

Let's ponder some alternatives and any weaknesses in the above, just in case.   If nothing else, this will help anticipate inflationist objections.   I say that because they argue that Star Destroyers ought to be super-dense, as in "25 times denser than water" super-dense.  That's basically crazy-pants dense, and doesn't make any sense given hydrofoamed permacrete and whatnot.

Let's take the third line of calculation:

5m/s = sqrt (m*0.00010775151181968114m^2/s^2)

Now, the 0.00yadda bit is pretty solid, being based on 19.6/181900.   The 19.6 bit can't be messed with too much unless an inflationist objector could claim Mon Calamari had way less gravity than Earth.  But let's assume 0.1g . . . that gives us 1.96/181900, or 2,320,000 kilograms . . . corrected, that'd be 5,820,000 kilograms (which is a familiar number, being the volume of a Galaxy Class ship in cubic meters, but that's neither here nor there right now).   That mass would result in a density of just 1660 kg/m^3, or over half again the density of water.  That's still not a huge increase.    And, put simply, it doesn't fly given the way we see clones and Ahsoka drop into the water . . . if anything, one could argue for a higher gravity, not less, which would drive down the mass, and thus the density.

Alternately, an inflationist objector could go after the 181900 bit, but again, that's pretty solid.  It's based on water's density, which doesn't change that much, the frontal area of the ship's engine, and the drag coefficient, which we've estimated pretty well, I think.  But, for fun, let's assume that I got the area all wrong it should be higher, and that the drag coefficient should be like 2.00 or something.   That gives us 500000 instead of 181900, and so 19.6/500000 yields 0.0000392.   The mass figure would then be 637755 kg, and the corrected mass about 4150000 kg, and the density would even then be only 1200 kg/m^3.

So, the only way to go is to try to attack the speed.

One objection would be that when we see an engine hitting bottom first (our heroes seem to ride the second, more banged up engine), it appears to be going faster than five meters per second.  (The engines were pretty much the first objects to arrive at the bottom, and they really ought to have been the densest, least-dragged sections of the ship all around.)

This is actually true, but only for that final scene. I used the speed reference against Ahsoka because I had not yet, at the time, done the figuring of the engine size.  The second engine, for instance, seems to take about 23 frames to pass a particular line during the hitting-bottom scene, suggesting (assuming 20m) a velocity of 26 meters per second.

That's hellaciously fast, and frankly suggests something is wrong with the hitting-bottom scene.  After all, as noted, when the engine passes Ahsoka, it had been in the water for 30 seconds.   That is, as far as I am aware, plenty of time for it to have reached terminal velocity.  (In air, it takes about 8 seconds for a skydiver to reach 90% of terminal velocity, and 3 seconds to reach 50% . . . why would an object require ten times that long to reach a fifth of the speed?)

There's also a limit at some point simply based on the fact that the people were able to hold on to the engine on the way down.  The forces could not have been that great if Amidala could hang on.  

The drag force on a human being at 5 meters per second would be .5*ρ*v^2*A*C . . . assuming half a square meter and a drag coefficient of 0.5, then we get

F = .5 * 1000kg/m^3 * (5 m/s)^2 * .5 m^2 * 0.5
F = 3125 kg m / s^2

That's 3125 newtons, or over 3kN.   A 70kg human being's weight is a force of about 700N and some people would be hard-pressed to even hold themselves up hanging on a bar for more than a minute.   This would require Amidala to be holding the equivalent of herself and four other people, which is bad enough.

At 26 meters per second, the force gets larger. 84,500N, to be precise.   That's like holding 120 people by your fingertips.   Good luck with that.

Put simply, it's not possible that it was going that fast while folks were on it.  Even if we assume some sort of protective effect due to well-chosen spots to hang onto (not unlike hanging on to a car's trunk rather than the hood if you're trying not to mess up your hair), it's much more realistic to believe they might be able to hang on at 5m/s as opposed to 26.

Also, that's not to mention that it takes some time for the engine to pass them after they let go.   Skywalker lets go and swims nearby, Ackbar lets go and is able to swim over to another spot, and the folks who let go then go belly-down like a skydiver wanting more hang-time don't recede at a high rate . . . a few meters per second at best.    Had the engine been doing 26m/s, and the terminal velocity of a sinking human belly-down being rather slower (near zero, I would think), the deceleration would've been tremendous . . . unless they weren't going that fast to begin with.

So, I'm thinking that the hitting-bottom scene was at a higher speed than the others . . . the opposite of slow-motion, in other words.   It is demonstrably inconsistent with every other scene that's part of the sinking event.

There's really no other way around it.

I mean, one could try to argue that when the first bottom-hitting engine cylinder hits bottom, it does so while turned almost sideways, meaning the drag coefficient is significantly reduced.   That's true, but doesn't help much.  If at a perfect sideways angle, the drag coefficient would be somewhere in the 0.45 range, and the area would be approximately 20*16.5.  So, let's run the numbers again:

V m/s = sqrt ((2*232000 kg*9.8m/s^2)/(1000kg/m^3*330m^2*0.45))
V = sqrt (4547200/148500)
V = sqrt (30.621)
V = 5.5 m/s

Oops.  The engine's extra length when sideways added to the frontal area and basically nullified the drag coefficient decrease.

Put simply, there's really no way for an inflationist to take this example and wind up significantly north of water's density without ending up in crazy-town.  While that hasn't stopped them before, I'm comfortable going with the old figure that I had before . . . Star Wars vessel densities ought to fall in the 500 to 1000 kg/m^3 range.

Exploding Batteries and Lots More

Let's ponder the ubiquitous lithium-ion battery.

Per Wikipedia the volumetric energy density is 900 to 1900 joules per cubic centimeter.   If you've ever opened up a laptop battery, you know that it's usually just a collection of normal-battery-shaped cells within a plastic container designed to match the lines of the laptop it will be used in.  Indeed, the cells themselves are often mistaken to be the size of an AA battery, which per Energizer's lithium AA battery datasheet is 8.0 cm^3.

In reality the cells are a bit larger, usually.  AA batteries are roughly 50mm in length and about 15mm in diameter, whereas the high-capacity Li-ion battery cells commonly found in laptop batteries are actually around 65mm long and 18mm in diameter.  Indeed, battery nomenclature would refer to the latter as an 18650 type, and you can get AA-size Li-ion batteries (in the native 3.6v) called 14500 . . . obviously they just call them by the "DDLL0" scheme, where D is diameter and L is length.  But let's digress . . .

We could do a cylinder volume calculation to try to get the volume of an 18650, but I don't know the wall thickness and some other potential complications, so we'll just roll with AA.
 
So let's ponder an eight-cell Li-ion laptop battery (pretty standard, though six-cell units also exist for netbooks and such) and assume AA size cells of the energy density provided.  Since we're thinking of cells a bit smaller than commonly used this may be a tad conservative, but that's okay for this purpose.

That's 64 cubic centimeters of volume, which at full ideal charge of 1900 joules will provide 121600 joules.

121 kilojoules is a good bit of energy.   That's the equivalent of two minutes of sunlight on a square meter of Earth's surface.   In kinetic terms, it is approximately the kinetic energy of the Tesla Model S , which is powered by thousands of 18650 batteries, doing about 26 miles per hour, sufficient to outpace most anyone except Usain Bolt at burst speed.

KE = .5 (1800) (11.6^2)
KE = 121104 J

That's about the same as an early 90's Ford Crown Victoria (at 1700kg curb weight) doing about 26.8 mph (later Crown Vics weigh about the same as the Tesla Model S).  Either way, that's enough to do a good bit of damage if you stood in front of it.  (Your risk of death by being hit by a car doing twenty miles per hour is a mere five percent, but at thirty miles per hour it's closer to forty percent, implying there's some threshold that a Crown Vic doing twenty-seven would likely cross.)  For the sunlight example, that energy is more than enough to ruin your sunbathing.  And all that energy is contained in a wee little laptop battery pack that you think little of (unless it's low on juice, in which case you think unprintable things).

Now, we can compare against some other things.  For instance, the energy density of modern/military dynamite is about 7.5 megajoules per kilogram, with old dynamite around 5 MJ/kg for purely nitroglycerin-based dynamite.  That's pretty close to the figure of TNT at 4.7 MJ/kg, or 7500 kJ/kg and 4700kJ/kg, respectively.   So, the energy in our Li-ion laptop battery back would be in the range of 16 to 25 grams (not kilograms, just grams) of explosive.

By volume, a classic cylindrical stick of dynamite, at about 20cm long and 3.2cm wide and weighing in at 0.186kg, has an energy of about 1.4 megajoules using newer formulations, or about one megajoule for older dynamite.  The stick's volume is 160.85 cubic centimeters, so taking megajoules per m^3 we find dynamite to be in the range of 6200 to 8700 megajoules per cubic meter, or 6200 to 8700 joules per cubic centimeter . . . several times the volumetric energy density for a Li-ion battery per Wikipedia.

(A laptop battery pack made of old dynamite or TNT would give you aplenty of energy to run your laptop but I, for one, have no intention of rushing out to buy such a battery pack.  I think you'll find they discharge a bit too quickly and recharging is a real hassle!)

The volume of our 16 to 25 grams of explosive would be equivalent to 1/7th to 1/10th of a stick of dynamite.  There aren't exactly a lot of Youtube videos covering such odd measurements of explosives.  However, people often try to simulate dynamite with flash powder as often found in fireworks, a much slower explosive.

As has been popularized, we know laptop batteries can explode, as seen in this "controlled demonstration".   But are they exploding like a tenth of a stick of dynamite?   No, they are not.  Here's a video reportedly showing a 10 gram flash powder device, all taped up for pipe bomb effect.  Here's a 20 gram one.  But, with the variability of flash powder and the devices, your joulage may vary.

And are the batteries actually exploding because of the release of their charge?   Not exactly, no . . . the main issue is that the battery material itself is flammable and pressurized, and overheating due to a short can cause overpressurization and potential ignition of the battery's electrolyte.

That distinction is important . . . that's energy separate from the actual charge of the battery.   If Li-ion batteries weren't basically flammable little pipe bombs, then there would be no comparison to make at all.

Pondering the Tesla, yes, it's got thousands of little flammable pipe bombs in it.  But is that really any worse than a tank full of gasoline?  Not really, no.

If the batteries go up, it isn't like she's releasing all her energy.   With her big battery rated for 85 kWh (306 megajoules, give or take), there's a lot of energy available . . . about twice what is needed to vaporize a human being based on water content, or the equivalent of 65kg (140lbs) of TNT or, by the megajoules, 40.8kg (89.9lbs) of dynamite.  Just for reference, here's 100lbs of dynamite against a house.  Compare that to the comparatively unexciting fire of a Tesla Model S after a collision with a metal object penetrated and damaged one of the 16 battery modules.  As Tesla put it in their press release, "the combustion energy of our battery pack is only about 10% of the energy contained in a gasoline tank".

So yes, Li-ion batteries are flammable, but not as energetically so as gasoline.

So what if you had a battery capable of holding a charge like that but which wasn't flammable?   Could you make the battery explode?   Maybe, if you tried hard enough, though I think your time would be better spent trying to get that puppy to market.   But even if you did, does that mean it would be releasing its charge?    Probably not.

Hmm . . . so with this in mind, let's ponder a phaser on overload.

I've recently seen someone try to argue that in various phaser overload events "the phaser overloaded and exploded, releasing all its energy", which "conclusively demonstrate lower total energy capacity" for phasers, which thus "appear to place the firepower in the low megajoule range".

Based on our ponderings thus far this seems unlikely.  By a similar rationale, this would be like calculating the yield of the Tesla fire and then deducing their acceleration from it.  Sorry, but that plan's no good.

True, there are the stated draws for a phaser rifle on unknown setting of a megajoule per second (with the fire in "The Mind's Eye" continuing for something like 16 seconds, suggesting the equivalent of a few kilograms of TNT (though perhaps not 15)).   Of course, as noted, that's a phaser at unknown setting being fired against some sort of phaser diagnostics target, so one would think the setting somewhere far south of maximum.

Then there's the phase pistol event from "Regeneration"[ENT] where Malcolm Reed doubles the particle yield.  But, to do so, he has to "increase power another five megajoules. Fire. Keep it going. Increase to seven megajoules. Try eight. Nine. The density's holding. Bring it up to ten."   Ironically, this weapon is also fired for 16 seconds.   The phrasing is a bit unclear ("another five megajoules" implies a prior raise of five megajoules or at least some figure in the megajoules, but then he pegs it to seven, suggesting a starting point around one, not to mention the whole power-in-joules thing), but it seems that we get multiple megajoules of energy expended in those seconds.

And, of course, there's Scotty draining phaser power packs, converting them into a pressurized fuel of some kind sufficient to provide enough energy to a shuttlecraft to achieve orbit, whatever that energy might be.   The process consumes much time and apparently has to despite the rush due to giant alien cavemen attacking the shuttle and its people . . . as Scotty notes, a phaser "can only drain so fast".

We don't know the required battery power of a phaser set to kill, but Captain Tracey did kill several hundred Yang with his phaser and multiple power packs in "The Omega Glory"[TOS3].  The kill settings are higher up the scale of phaser settings, suggesting a significant battery event.  150 to 200 kills per power pack wouldn't be anything to sneeze at, even in less efficient uses like widebeam or just via sweeping the weapon while firing.

Note that none of these examples are about the effective yield of a phaser, i.e. its effect on targets when fired.   Vaporizing people and rocks can require hundreds of megajoules or more of effective yield.  We are distinguishing here between the actual energy of the weapon's power cells and its effective yield.

This is a distinction not made by the person claiming an overloading phaser is releasing all its energy and thus providing a constraint on its firepower.

So, the argument is basically akin to saying that if you overload your laptop (or even better, a laser pointer) you can make the batteries release all their energy in an explosion.   Or for an alternate example, that you can take that Tesla and overload it, causing the battery packs to detonate with a house-splintering effect.  Or that you can take the Crown Vic and overload it somehow, making the gas tank explode by mechanically vaporizing the fuel to achieve the best air-fuel mix.

Sorry, but no.

Of course, some might argue those are bad analogies, but how would they know?  Put simply, we don't know the mechanics of a phaser overload event.  We don't even really know the innards of a phaser in the first place, for that matter.   We know from "The Mind's Eye"[TNG4] that there's a prefire chamber (with a pulse frequency), an emitter aperture, an energy cell, and a discharge crystal, and that's about it.    We don't even know what the battery is made of or anything about how it operates.

Now, assuming commonality, we can presume that the energy cell is (sarium) krellide, as found on shuttles.   Geordi, in "In Theory"[TNG4], tells Picard that his "krellide storage cells are losing their charge".  Krellide power cells were also used in a years-unused Vulcan transmitter in "The Andorian Incident" from 200 years prior to Geordi's statement, and they still had enough juice to call the ship from the surface.  There's also a shot of the "energy signature" of the shuttlepod from "Descent, Pt. I"[TNG6].  It shows two 750 millicochrane impulse driver engines, eight hot gas thrusters, and three sarium krellide power cells.

And yes, sarium krellide is capable of being used as an explosive via some unknown detonator, per "Night Terrors" . . . per Bernd's transcript of the screen, Clancium oxide was a "Medium-yield explosive used for high-volume heat generation in emergency situations. This compound is preferred to conventional sarium krellide explosives because of superior thermal dispersion characteristics in low-pressure atmospheres."

No, that doesn't make a great deal of sense on a first read.  The only other medium-yield explosive mentioned is "Todotracium", a "Controllable medium-yield propellant used in small solid rocket motor devices and emergency disconnect explosive bolts."    Presumably the difference between a medium-yield propellant used in explosive bolts and a medium-yield explosive used for high-volume heat generation would be that the latter puts out hotter gas which, for whatever reason, disperses better in low-pressure atmospheres compared to sarium krellide, somehow or other.

In any event, that comparative (we don't get an entry for sarium krellide) does not necessarily imply that sarium krellide is volatile.  The "Night Terrors" list includes things like "Neussite 283", a "Highly stable liquid explosive used for industrial infusion charge applications and manufacturing. Ignited by microwave pulse detonator."   Another substance mentioned is ignited by "standard microwave pulse ignition devices".  In other words, you'd probably never have a problem storing Neussite 283 unless you use a microwave pulse detonator or similar special doohickey, and many of the explosives on the list are similarly troublesome to make blow.   On the other hand, some are specifically listed as being unstable or volatile.

That all said, one interesting possibility is that it actually makes a bit of sense that sarium krellide would have potential explosive characteristics . . . after all, these people use plasma conduits for their power systems, so it seems as if your batteries would need to be capable of providing plasma.  If the stuff carries a charge, to boot, then it's potentially a self-powered plasma power generator.  That would also make Scotty draining phasers into fuel make sense, assuming sarium krellide were in use for phasers.

On the other hand, TOS shuttle batteries apparently couldn't be converted in the fashion of the phasers . . . Scotty, while draining phasers, used the batteries of the shuttle to electrify the shuttle's hull, and needed their power for fuel ignition.  One would've thought that the batteries of a shuttle would be larger and more powerful than those for a few phasers.

But in any case, the money point here is that while sarium krellide can be made to explode by some unknown means, it also can carry a charge.

And back to the main point, does a phaser on overload detonate the batteries or release the charge, or both?    For all we know, a phaser on overload just disconnects some critical bit that makes it actually fire so it overloads the prefire chamber, merely dismantling the battery in the subsequent smallish explosion.

Certainly that seems more consistent with the relatively low yields some phaser overloads have shown.

Put simply, we don't have a firm grasp on what exactly happens when a phaser is overloaded.  However, since we have canon statements of batteries with many megajoules available, pointing to a low-yield small-fireworks-grade overload and declaring that to represent maximum phaser firepower is exceptionally weak at best, and just plain disingenuous at worst.

Transparisteel

Windows in Star Wars are often described as being transparisteel.  Padme's maneuvers in Theed on Naboo at the end of TPM required blasting through transparisteel windows, leaving shards of it and broken permacrete (which we covered in a recent entry).

The windows on Kamino are said to be transparisteel, as well as those of the skyscrapers of Coruscant, in the AotC novelization.  We saw Kenobi jump through one.

In the RotS novelization, the fighter canopies of the Jedi fighter are also said to be transparisteel, as well as the "view wall" on the Separatist ship's bridge with spidering cracks in it from a glancing hit from a starfighter, as well as Grievous's thrown spear blowing it wide open.

And, in the TCW movie novelization, we learn that Palpatine's big office window is also transparisteel.  Actually, the RotS novelization calls it "armored transparisteel".

This is interesting given the fact that we've seen that window broken more than once . . . Windu takes it out with a single swipe of his lightsaber, causing it to fracture into a million pieces.   Cad Bane's takeover of the building in TCW featured clones rappelling down and swinging through it in "Hostage Crisis"[TCW1], with only a boot doing the breaking.

Suffice it to say that other than the claimed pre-damage to the window from the RotS example, not visible in the film itself, there's no evidence of transparisteel being particularly interesting.  Even armored transparisteel acts about like we would expect of normal glass . . . brittle and not resistant to much of anything.

This is simply modern experience carried into science fiction . . . transparent things = glass = brittle material . . . that need not be correct.   Indeed, it hasn't even been necessarily correct on our own world for a long time . . . things like plexiglass and transparent ceramics have been with us for awhile, and transparent aluminum apparently really was left behind by Scotty in the 80's, though it took awhile to get finished . . . probably because the guy was on a Mac.

Transparisteel or transparent aluminum are terms suggesting a transparent metal, and thus they should act more like metal . . . bending instead of shattering, or breaking in a more metallic, tearing manner.

Star Trek falls victim to this, too, what with the little circular window on the top of the bridge breaking open during the Generations crash.   But no matter what, it's a bad idea.

Travel Time Continuity

Per the novelization to ANH, we know that the trip from Tatooine to Alderaan and back was expected to take about three weeks, since that's how long Han told Jabba it would be before he would be back with the money from the trip.

Of course, I don't expect the JJ films to make use of such figures . . . after all, his Trek film shortened the trip to Vulcan during the TOS era from the "days" of TMP to seemingly mere minutes, which is just crap.

That's not just his own failing, of course . . . Star Trek: First Contact has Picard order battlestations before going to warp from the Romulan Neutral Zone toward Earth, which seems quite unnecessary if the trip's going to be longer than even a couple of hours, and of course there are several similar examples.

It's a curiously easy trap to fall into for writers.   Even the old series 24 that ostensibly ran in realistic time tended to have people driving across large cities in mere minutes.   But, it is still a bit of weak writing either way, and even moreso in a science fiction setting.   It's one thing to have an unusually traffic-free trip rather than have Keifer Sutherland looking intense and pondering the torture of other drivers for a quarter of a season's episodes, but with science fiction you have to keep a firmer hand because otherwise it becomes too obvious that your ship moves at the speed of plot.   That's not world-building . . . that's just haphazard, ad hoc, and other things that should be insulting to writers and moreso the movie-goer or series-watcher.

Folks who cannot write interesting stories within the established continuity simply aren't trying hard enough to do their jobs correctly, and I think that applies to both characterizations and technology.   I realize that's a bold statement and smells of excess nerdiness, but it's true all the same.  

Locating Jouret IV

While writing the last post, I found reference to Jouret IV showing up on a star chart in "Child's Play"[VOY].

http://en.memory-alpha.org/wiki/Jouret_IV

I pulled up the episode on StarTrek.com and checked for the context. Turns out there really wasn't any context except for Icheb just going nuts multitasking with all kinds of screens going in Astrometrics. So, the fact that Jouret IV was shown in an image near Rigel and Vega means nothing.

But out of curiosity (since the real Rigel is like 3000 LY away as I recall whereas Vega is nextdoor), I went ahead and looked around further.

http://www.atlasoftheuniverse.com/50lys.html

Vega is "west-northwest" of us and about ten light-years "higher", at a distance of about 25 light-years. Rigel is listed at that site as 770 LY distant (Wikipedia, more recently, gives it 860). But so near as I can tell from http://www.atlasoftheuniverse.com/5000lys.html Rigel ought to be basically in the complete opposite direction from Vega.

That suggests that Icheb's star chart was not a "top down" map, but a projection from some location that is not Earth.

However, ignoring the multitude of Rigels some suggest as a way of dealing with Star Trek, this could imply that, projected two-dimensionally, Jourey IV (which I'm going to spell that way because I keep typing a Y there so dammit) lies along a line that includes Rigel and Vega.

Of course, then there's Pollux IV on that map, too, at which point the whole plan goes to poo. Pollux is almost due "south" of us and rather higher, which just kills the angles. It's 34 light-years away per the Atlas site.

This is actually interesting, though, because if we ditch the Rigel and keep a line from Pollux to Vega, we still sort of basically end up pointing roughly 45 degrees west, or toward the northwest. (We could also go southeast, in principle, but I like that less.)

That would put Joureydammit IV off to the northwest, instead of the north-northeast (i.e. toward Borg space) as commonly assumed. (Well, I say "commonly" . . . this guy puts it in weirdville in the F/K/R triangle region, about 75 LY from Sol to the ESE: http://www.sttff.net/AST_MAP.html )

The westerly positioning could actually dovetail pretty nicely with my recent ruminations on the Borg which featured the "Borg in the Northwest" hypothesis.

http://dsg2k.blogspot.com/2014/03/the-borg-have-been-busy-ii-assimilation.html

JouretokayfineIbackspacedthistime IV being toward the northwest, in other words, actually fits that, and we could even go further and suggest the presence of a transwarp doomaflotchy there. (The one a light-year from Earth in the Voyager finale would just be a new thing or fluke).

Ivor Prime and the Federation Border

So, in First Contact, Admiral Hayes awakens Picard with the news from DS5 that "our colony on Ivor Prime was destroyed this morning".  

(Note that this is a very different sort of scenario than what we saw with Jouret IV at the start of "The Best of Both Worlds" . . . in that case, the colony was destroyed but there was a significant delay in this being found out.  But I digress . . . )

When Picard briefs his officers sometime later, he notes that the Borg will cross the Federation border in less than an hour.

So wait . . . what's the story with Ivor Prime, then?   The Federation has a colony there but they consider it outside their border?

This is a bit odd.   Either it's within someone else's border (could it be a Cardie DMZ world?  Or within the territory of some species like the Sheliak but friendlier (i.e. they can't settle it but they let the Federation)?) or it's in non-aligned space that the Federation has planted a colony on but not claimed.

The whole bit about the border would be interesting in the latter case, because that would suggest declared borders without someone else around to make them meaningful.     That doesn't make too much sense, really, unless the "border" is more of an informal term relating to the territory of the Federation core systems.

Note here that I'm against the "swiss cheese Federation" concept wherever possible, but Ivor Prime does seem to suggest some non-contiguous-ness.

The thought that Ivor Prime is related in some fashion to the Cardassian DMZ thing is interesting, except one would think a Borg attack, even if it was on a formerly Federation colony, would have given the Cardassians and Dominion some pause (or maybe it did, and that's why they didn't attack for a bit longer).

Anyway, I don't have an answer here . . . it's just an odd bit worth a few minutes pondering.