Inadequate hull materials

[rust]

The "omni-directional" has been proven by direct observation.

How do you prove with an observation from one point only (our solar
system) that a radiation with an origin far from this point of observa-
tion is omnidirectional ?

Without a corresponding direct observation from at least one other
point all you can get is an assumption.

Besides, without any intention to be impolite: I trust NASA's scientists
a bit more than your statements, and just a few weeks ago they were
sure enough that:

As the star collapses, jets of particles and gamma radiation produced by
a newborn black hole blast in opposite directions from the stellar core.

http://www.nasa.gov/mission_pages/swift/bursts/500th.html

 

[DFW]

That's nice.

 

[rinku]

OTOH any in-system flight that takes more than 168h+Transfer to 100D will most likely be made by a J1 capabel craft micro-jumping since it is just as fast and safer than thrusting

Apart from in-system flights that have an origin or destination within the 100D of the star. You might also have companion stars and gas giants that temporarily (i.e. for months at a time) obscure a target and require some realspace thrusting.

There is also the issue of economy; if you have more than one important world within a system, it is a lot cheaper to shift cargo between them with non-starships. A 1000 ton J-1 ship uses 100 tons of fuel, which is Cr50,000 extra per trip (refined), and which will add MCr50 to the cost of the ship while reducing the cargo capacity by 130 dTons.

And to put things in perspective - 168 hours at 1G is about 6 AU. So we're taking about a trip further out than Jupiter's orbit.

 

[DFW]

VERY good points Rinku. Econ 100.

 

[rinku]

Q:

How did you compute the distance travelled? With 1/2 accel, turnover, 1/2 decel or a full 168h accel?

Actually, I just judged it from the travel time table, but that's been worked out from 1/2 accel/turnover/1/2 decel. It's an exact copy of the old Book 2 one. Don't have it to hand, but it has the formula (which in itself is a big simplification as it assumes linear travel, but is good enough for the purpose).

Edit: The Book 2 formula is D=A(T^2)/4, where D is distance in metres, T is time in seconds and A is acceleration in m/s^2.

As for J-Fuel this depends on where the second target in a system is and what ship is used. While the cost for engine and the space are fixed, fuel prices can be nil if the target is a gas giant.

True to a degree, but refuelling takes time as well. And often, time is money, or risk. A big, unstreamlined cargo ship may take more time to refuel for the jump than it saves by direct thrusting. It's all very circumstantial and will vary from system to system.

Another factor is in system security. How is the region between the two points of interest patroled?

Excellent point, though most attacks are still going to occur near the points of interest, unless it's a planned ambush. If the system's astrography makes in-system traffic common, you'd expect patrols along the same areas. If traffic is *very* common (i.e. two or more populous inner system planets with complementary resources) it might be too well trafficked for pirates anyway.

 

[Galadrion]

Hm. I seem to be a bit late chiming in on this issue. My personal feeling is that gravatic propulsion drives, in a similar manner to jump drives (which are derivative from gravatic science, after all), work by projecting a "bubble" of altered space around the ship. In the case of the maneuver field, the bubble remains in "normal" space and is accelerated, rather than being projected into jump space. As a side effect, however, the altered space is going to act as a low-level protection field against small particles, probably reducing their inertia in the same manner as the inertia of the ship and everything in it.

Would such an "inertial shield" serve as protection from incoming weapons? To a small extent, it would... but not against energy fire, and probably not against significant masses. Such a defense would work most effectively against small masses and those not under acceleration. (Sand clouds would be fairly efficiently cleared, but pebble rounds are probably larger than the field could effectively handle -- although the damage would be worse without the field effect. Missiles, since they are under their own thrust, would negate the minor effect of the gravatic drive field.)

DISCLAIMER: From a game effect, "crunchy rules" standpoint, this explanation has no effect. In-game, combat works just as written. This is only my home-rule handwavium explanation of why ships can attain dangerously high velocities without interplanetary dust clouds sandblasting holes in the hull material...

 

[DFW]

Such a defense would work most effectively against small masses and those not under acceleration. (Sand clouds would be fairly efficiently cleared, but pebble rounds are probably larger than the field could effectively handle -- although the damage would be worse without the field effect. Missiles, since they are under their own thrust, would negate the minor effect of the gravatic drive field.)

Interesting, but TOTALLY invalidates F = ma. A bit too handwaivium.

 

[Galadrion]

Interesting, but TOTALLY invalidates F = ma. A bit too handwaivium.

*Grin* And reactionless thrusters don't invalidate it? I'm afraid, neighbor, that if you're going to accept FTL travel, some of the laws of physics are going to have to give a bit of way.

 

[DFW]

*Grin* And reactionless thrusters don't invalidate it? I'm afraid, neighbor, that if you're going to accept FTL travel, some of the laws of physics are going to have to give a bit of way.

Too many problems with the bubble M-drive. If you cut power you stop. It would break too many things in the game, including missiles. THAT is the criteria...

 

[Galadrion]

Too many problems with the bubble M-drive. If you cut power you stop. It would break too many things in the game, including missiles. THAT is the criteria...

Not necessarily. What I had in mind was a field which reduces, but does not eliminate inertia. This would allow a much smaller impulse to generate those multi-gravity accelerations... and would also greatly reduce the impact of space-borne debris. In this case, cutting power would simply allow inertia within the bubble to go back to "galactic norm", although doing so at high speeds does carry obvious risks. (For that reason, cutting power while in motion would not normally be done.) Also note that the inertial reduction is not the primary effect of the field, merely a useful side effect; the primary effect is, as always, the acceleration of the ship. (Another important point: the effect is acceleration. Acceleration, not movement. That means that if you cut power, you stop accelerating. Stopping an object's acceleration does not stop that object's motion in space. It means that the object's velocity stops changing, until you start accelerating that object once more.)

 

[rinku]

Hmm. I'm also a bit leary of introducing Doc Smith style intertialess (or interia reducing) drives.

However, you could still assume a grav manipulation bubble effect that acts as a micro-mass deflector. Magnetic fields will do this for charged particles, after all. Instead of stopping them flat, they skim away or are diverted around the ship.

But it won't stop a missile or anything with serious momentum.

 

[Galadrion]

Precisely, Rinku. The handwavium doesn't particularly matter -- you can call it an inertial sump, a gravatic charge, strange matter pseudo-spin charge or whatever -- as long as it does the job you need it to do. In this case, we need some effect of an operating gravatic maneuver drive which will prevent space debris from impeding a high-velocity ship. If this was a fantasy game, the referee would just say "magic" and be done with it. Since this is a science fiction game, the referee has to fall back on Clarke's statement and come up with some sufficiently advanced technology.

 

[rinku]

Yeah, but the explanation DOES matter as you have to stick to the logical consequences of it.

For example, are gravitic drives truly reactionless, or are they pushing against masses (like stars and planets), and in fact conserving momentum?

If I turn off my handwavium devices, or if they are turned off for me by obliging space pirates, how does this affect my ship's motion?

Are there interesting side-effects of the device that make for useful story hooks? (THIS is a cornerstone of science fiction)

 

[DFW]

Not necessarily. What I had in mind was a field which reduces, but does not eliminate inertia.

Goose/Gander- If it protects against moving matter then it would have to protect against missiles. Like I said, too many unintended consequences. From a game design perspective it is simpler to have harder hulls and have the missiles be an extreme anti-armour.

 

[DFW]

But it won't stop a missile or anything with serious momentum.

momentum: The ‘quantity of motion’ of a moving body; the product of the mass by the velocity of a body.

We are talking about momentum that is MORE than a missile...

 

[FreeTrav]

Actually the drive described by Galadrion does exist in the "GDW settings" as the:

"Jerome-Effect Inertialess Micro-Transistion Drive"

aka

STUTTERWARP

The standard engine for 2300AD ships complete with a nice set of capabilities and problems

No. The StutterWarp drive has no effect on inertial mass or motion, nor does it involve an inertia-affecting field around the ship; it merely takes advantage of an undocumented effect of handwavium that allows the phenomenon of quantum tunnelling to be controlled sufficiently to cause a ship to relocate while remaining intact. Since the ship does not "move" within the meaning of that word in classical physics, the limitation on how far how fast becomes a function of the frequency at which QT events can be initiated. The rest of the described effects - "charge buildup", et cetera - are more handwavium effects.

Galadrion's inertia-modifying drive is closer, conceptually, to the "Bergenholm" of the Lensman series by Edward Elmer ("Doc") Smith, or possibly to the "spindizzy" of the Cities in Flight tetralogy by James Blish.

 

[MarkB]

The simplest solution for missiles is to equip them with some minor handwavium that negates the handwavium you're using to protect the ship against impacts, as a deliberate design feature.

So for instance, if a deflection effect against freely-moving objects is a side effect of the drive's gravitics, then assume that missiles are also equipped with gravitic drives, and that when two gravitically-driven objects collide, their respective deflection effects cancel each other out, exposing both to the full impact.

 

[TC]

C.J Cherryh's Universe is quite traveller friendly in most case, with some obvious deviations.

My point is her real space manuever drives have something along the lines of a grvitic bow shockwave that deflects the flotsam and jetsum of space, but not lage things, those you manuever around.

which make immenet sense to me, I don't drive into telephone poles, but can drive through clouds of gnats and sketters without worry.

 

[rinku]

Missiles are actively homing on the target; space debris is not. That's all the difference you need. You only need to nudge a micro mass to make it miss, though bigger rocks travelling at solar orbital speed aren't going to be deflected so easily.

Hmm... I just realised that the new High Guard has left out repulsors for some reason. These used to be THE anti-missile defense, starting at TL12, even.

 

[DFW]

Hmm... I just realised that the new High Guard has left out repulsors for some reason. These used to be THE anti-missile defense, starting at TL12, even.

You're right. I wonder what happened.