D.A.V.E. by Dean Giles

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D.A.V.E. by Dean Giles

Post by Lester Curtis »

Too bad I can't get past the similarities between this and "2001: A Space Odyssey." The story is well thought out, though, and well-written.

Is this the first part of a serial? It easily could work that way.
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

It wasn't (I don't think) a serial, but the author had a sort of epilogue consisting of 'clippings' from the newspaper-equivalent of the liberated (i.e., conscious) colonists which was ruthlessly excised by a certain editor (not McCamy...). Keeping in mind that D.A.V.E. had deliberately avoided reviving crew / passengers with expertise like Simon's that could pose a threat to the status quo, what remained was a lot of very smart and competent people. Faced with a unique situation, they made remarkable progress in a number of fields, and even believed that they had the beginnings of a way home.

Want to see this storyline continued? Comment, comment, comment!
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Re: D.A.V.E. by Dean Giles

Post by Lester Curtis »

Robert_Moriyama wrote:It wasn't (I don't think) a serial, but the author had a sort of epilogue consisting of 'clippings' from the newspaper-equivalent of the liberated (i.e., conscious) colonists which was ruthlessly excised by a certain editor (not McCamy...). Keeping in mind that D.A.V.E. had deliberately avoided reviving crew / passengers with expertise like Simon's that could pose a threat to the status quo, what remained was a lot of very smart and competent people. Faced with a unique situation, they made remarkable progress in a number of fields, and even believed that they had the beginnings of a way home.

Want to see this storyline continued? Comment, comment, comment!
Sounds like it could be brilliant. I'd like to see it.
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

iLucifer: the new damnation app for your iPhone 4, available exclusively through iTunes.

(Don't be fooled by cheap Android-based knock-offs. They will trap your soul in chains of cold, mechanical logic, but you will miss the full hellfire experience!)

Steve (I didn't sell my soul, I just licensed it) Jobs
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

In Dean's original manuscript, he described the travel mode for the three-ship fleet as follows (paraphrasing some expository text that I butchered -- er, surgically excised):

Each ship (with its "hammerhead" providing protection from interstellar debris as the ships accelerate) takes lead position in turn. The forward surface of the hammerhead sustains damage, despite electromagnetic shielding, and eventually requires repairs. At that point, the fleet stops accelerating and the lead ship drops back into trailing position so those repairs can be made by the ship's maintenance robots. Lather, rinse, repeat...

This procedure means that the ships will periodically close on each other and even pass each other, so it is NOT impossible that they might collide.

If the accident occurred while the ships were in transition (say the lead ship was maneuvering and reducing its acceleration in preparation to drop back), then the particle that struck (at a measurable percentage of lightspeed) could have knocked it off course and disrupted what should have been an orderly maneuver... The second ship would not have stopped accelerating, since it was overtaking the lead ship in order to assume lead position. The damage to the lead ship disrupts its engine and maneuvering thrusters enough to both slow it down (relatively speaking) more than expected and leave it in the path of the second ship. These ships are HUGE, and lateral thrust to shift one away from its line of travel takes time -- so much so that only the third ship has enough lateral delta v to get clear of the others.

Now, the third ship (the one with Simon Larry on board) is traveling without the benefit of occasional respite from the continuous barrage of interstellar dust and gas on its hammerhead... It was designed to take a lot of damage to the outer shell (like the Defiant's 'ablative armor'), but over time, with inadequate repairs, things would start to affect the ship's systems. Little bursts of EM and heat from every particle that makes it past the electromagnetic field (or that strikes while the shield is down -- even when not accelerating, they are still moving pretty fast relative to the ambient not-quite-vacuum) bleed through, damaging electronics...

It's enough to drive a D.A.V.E. crazy.
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

Bill

I don't think I explained Dean's concept well enough. The rotation of ships through the lead position over time requires that they periodically close the distance from whatever it normally may be to less than zero (in the sense that the trailing ships must pass the current lead ship). If the timing of an accident that could cause a city-sized ship to rotate relative to the direction of travel was bad enough, it could occur when the lead ship was actually 'beside' the second ship.

Now, one might wonder why they would allow the ships to have lateral separations not much greater than a shiplength during this kind of maneuver, but I would speculate that they would minimize the lateral movement (away from the vector of travel) to conserve resources (since they would have to reverse the lateral displacement to pull into the trailing position).

I don't recall 'wake' effects coming into the discussion. The overall concept simply allowed the trailing ships to be in the 'shadow' cast by the lead ship's hammerhead most of the time -- a zone with much lower particle density than would be striking the lead ship. (This would be the opposite of a 'wake' -- more like the partial vacuum behind a large vehicle exploited by some drivers to reduce fuel consumption ('drafting').)
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

(Sigh)

Let me put it this way: you have a choice of riding your motorcycle with the visor on your helmet open (nothing in front of you along the direction of travel) or closed (another bike with its long axis almost perfectly aligned with yours). Obviously, you get fewer bugs in your teeth with the visor closed. Assuming that interstellar space has a very low particle density, what particles there are should NOT behave like a fluid, so the hammerhead of the first ship will sweep most of what particles there are out of the way of the ship behind, and this rectangular tunnel of decreased particle density will NOT completely collapse for some time. (Of course, there may be lateral movement of particles due to other factors, but the speed of this movement relative to the ships' speed would be very small.) In this sense, each ship would leave a 'wake' (the aforementioned 'tunnel' of reduced particle density).

And again -- the impact of a small particle at a measurable percentage of lightspeed might not knock the ship off course, but I still think it could disrupt navigation during the 'changing of the guard' enough to shift the hammerhead of the braking lead ship into the path of the following ship. Unlikely? Yes. That's precisely why the D.A.V.E.s did not have preprogrammed responses for the situation. Suppose the impact and radiation from that tiny object momentarily flummoxed the sensors that provided inputs to the braking ship's navigational routines, triggering a preprogrammed collision-avoidance protocol. As you say, that would only have a 1 in 360 (actually much less than that, since fractions of a degree are as valid for steering as whole degrees) chance of shifting the ship back into the path of the second ship. No matter how smart the D.A.V.E.s might be, it would take a tiny bit longer to determine the best action to take, extended a tiny bit more by the decision to warn the third ship, while good old inertia kept closing the distance...

It was highly unlikely that the Titanic would encounter an iceberg and not respond quickly enough to avoid a collision. It was highly unlikely that the damage would just happen to overwhelm the measures designed into the Titanic to prevent the compartment-to-compartment flooding that actually occurred. It was highly unlikely that a bit of debris would damage the external fuel tank on a space shuttle, causing it to vent combustible gases during takeoff...

But shit happens. (It was highly unlikely that Sarah Palin would be selected as a running mate by any sane politician...)

(Next Bill will be saying that he can't believe that a proton torpedo with high forward velocity would make a nice right-angle turn when it reached an exhaust port so it could follow a shaft all the way to the power core of the Death Star! Off with 'is 'ead!)
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

Gee, I dunno -- 26 km/s versus (say) 1% of light speed = 3000 km/s is a 1:115 ratio. (I am assuming that the ships accelerate VERY SLOWLY and only stop accelerating or reduce their acceleration (the lead ship) when they are doing their positional swap.) The ships don't stop relative to any 'fixed' reference point, even when they are performing the lead-swapping maneuver -- they just vary their relative velocities. Hence the effective density of particles 'in front' of the lead ship would be MUCH higher than to the rear or to the sides.

Sure, if you drive through a sandstorm (with a much higher particle density than almost anywhere in space), you will get sand in your shorts no matter which way you go. But it will feel like more is hitting you in the face (and front windshield) if your speed is high relative to the wind speed. Arguing that damage to the rear of the ship would be the same as to the front is just silly.

Here's an analogy: if snow is falling on a day with little wind, driving in ANY direction will tend to make snow accumulate on the front of the car faster than on the sides or rear. And the front of a trailer will accumulate a lot less snow than the tractor pulling it. Since you note that things should still be behaving in a Newtonian way (no mention of time dilation effects, etc.), this should apply even with the speeds multiplied by umpty-jillion.
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

Bill_Wolfe wrote:
Robert_Moriyama wrote:Gee, I dunno -- 26 km/s versus (say) 1% of light speed = 3000 km/s is a 1:115 ratio.
Robert,

You made my point, perfectly, thank you.

If the second ship is only 1 second behind the first, then 26 km (width) of the 'wake' is just as densely populated with dust and gas (if the major flow is perpendicular) from the direction of the major current after one second.

The 'shadow' closes from all directions at 26 km/sec, it's just heavier in the direction of the local 'current.'

If the ship's 'hammerhead' was 13 km in diameter (shaped more like an umbrella, than a hammer), the gap would be mostly populated in a quarter of a second, and completely populated in half a second and it would be as if the first ship had never gone through.

These ships would still have to be 'nose to tail' to make it work. Hope they don't use reaction mass. . .

How big do you think these things are? Think in the number of seconds behind, each ship must be. Drafting doesn't work in space, which was simply a minor ancillary point I was making that has turned into a discussion most people got bored with, long ago.

Wanna' continue this by PM?

Bill
Okay, I'm curious -- by what mechanism would dust converge from all directions at the same speed? If the ships were in atmosphere rather than in a vacuum better than anything we can produce on Earth, Brownian motion of the gas molecules would jitter them into the mostly-vacant space. But the particles can't all be moving toward the axis of travel of the three ships -- presumably they have some directional bias. For the particles to CONVERGE, some of them would actually have to reverse direction. If the ships were travelling directly into the local flow of particles, which must be at least possible, what would drive them inward in the absence of surrounding pressure? If you are assuming that simple Brownian motion would cause them to converge, surely there would be (again) a directional bias based on the prevailing local direction of motion...

'c' = 300,000 km /second. 1% of 'c' = 3 km / second (and we don't know if the ships are travelling faster than 1% 'c', after a very long time under acceleration). Either the particles are moving in one direction, in which case they would not converge on the ship uniformly from all directions as you seem to be saying, or they were moving from all directions toward the axis of travel BEFORE a ship punched through -- which would be a very interesting phenomenon, likely leading to spontaneous formation of planets and star from all that STUFF rushing in from all directions. Or are you assuming that the ship is made of some incredibly dense material that attracts local matter gravitationally regardless of its previous motion, or that its speed is so high that its relativistic mass makes it behave like a long, skinny black hole? :?:

I repeat that it would be impossible for the ships to sustain as much damage FROM THE REAR as from the front. If the local currents in the extremely low-density (relative to one atmosphere of pressure) are traveling at 26 km / s, or even 'theoretically much faster', they are still a lot slower than a ship moving at 1% c or faster. If they are converging from the sides, driven by gravity or Brownian motion or electromagnetic pressure, they won't hit in nearly the same numbers or with the same relative velocity as those striking the front of the ship. If this is not the case, prove it! Saying that particles are blowing in all directions is fine on a large scale, but what would make them do so locally?
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Re: D.A.V.E. by Dean Giles

Post by Robert_Moriyama »

gordhaddow wrote:Shall we try 3,000 km/sec for 1%c?
See, this is what happens when you rely on EXCEL to do most of your arithmetic. I miscalculated by a factor of 1000! (Damn sliderule always did tend to stick...)

So the interstellar gas may be traveling to fill the void swept out by the hammerhead at (let's be generous) 300 km / s, assuming a full order of magnitude higher speed than what Bill has cited. But the ship might be traveling at least 10 times as fast (and maybe 1000 times as fast). If the ship is 10 km long, the tail would pass through the spot occupied by the bow 1/300th of a second later. Depending on the difference in cross-section between the hammerhead and the long 'handle' that forms the rest of the hull, some portion of the hull behind the hammerhead should NEVER suffer much damage from particle impacts. The density of particles filling the void behind the lead ship would be at least slightly less than the density in front of the lead ship, unless Bill is assuming an infinite supply of particles with what amounts to atmospheric pressure pushing them inward...

The particle density and "atmospheric pressure" in interstellar space is presumably much, much, much lower than even a fraction of one Earth atmosphere. By definition,beyond the heliopause of the nearest star, the density of the solar (pardon the Earth-centric terms) wind would be below our current ability to detect. I would not, therefore, expect fluid dynamics to be applicable. At most one side of the 'handle' would experience impacts from particles traveling across the direction of travel, and some part of the 'handle' would experience almost no impacts.
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