Relativistic Weapons
- Thread starter Gentleman John
- Start date
Supergamera
Mongoose
Yes, you can come up with detection and defenses for near-c rocks, but then the setting becomes full of worlds surrounded by orbital protection, with everyone worried about the next "God Hammer" to strike. It gets worse if you allow high vectors to translate through Jump, as it cuts your warning time way down.
It seems better to stick some limit on drives, perhaps requiring reaction mass above some small fraction of c and limiting Jump entry vectors. Even the information on the Ancients indicates that they accelerated their asteroids with teleportation gates, rather than with drives.
It seems better to stick some limit on drives, perhaps requiring reaction mass above some small fraction of c and limiting Jump entry vectors. Even the information on the Ancients indicates that they accelerated their asteroids with teleportation gates, rather than with drives.
captainjack23
Cosmic Mongoose
EDG said:That's not mentioned at all in the 1981 edition that I have (at least, not on page 6). So I guess it got dropped between editions?
(now, which is proper canon, the rule that came first but got dropped later, or the rule that came later but stayed in?. Semi-serious question, because a lot of the canonistas treat "first publication" as higher priority... but the changes quietly made between CT printings screws that all up).
Heh. So revising rules between editions is screwing things up. My goodness.
Seriously, if you (as a canonista) want to make a canon issue about it, one might point out that not only was it first, if it wasn't specifically contradicted, just ignored, it still stands.....
captainjack23
Cosmic Mongoose
Supergamera said:
Vectors out of jump can be handled by randomly reassigning direction as an effect of jump exit....
Max speeds are a problem if one wants compatibility with earlier statements about the traveller Universe (speeds up to .7 c explicitly allowed, limit based on hull construction/armor).
the observations about the ancients do suggest that M drive might be a pseudovelocity (ie good for movement, if not impact potential).
Regardless, the tech of the OTU is clearly able to accelerate things without M drive tech - and near relativistic speeds aren't necessary to use kinetic planet impactors...Space opera planet busters shouldn't be cheap and easy. .so, I suspect, if the OTU flavored universe is to be preserved, the subject is best left unexplained -can be used for special situations (adventures) but need no further examination.
Supergamera said:
Actually, I don't think that you can.
Traveller detection ranges are typically under 500,000 km. At 0.5 C you will only have 3-6 seconds from detection until it is out of range. Even if you can detect a small object on a ballisic trajectory at maximum range, the gunner will just begin to react (3-5 seconds per DOT statistics) by the time it is out of range.
captainjack23
Cosmic Mongoose
atpollard said:
It all depends on where you detect them. The critical time is not the reaction time of the gunner, but the time from detect to impact. Gunner reaction is really only an issue with a target that is maneuvering; otherwise, the track can be plotted and predicted.
In any case, its moot. You can interecpt, perhaps; but what then ? (see previous)-the type S has an impact energy of 1728 Gigatons at .5c.......
Didn't the first printing of Book Two actually say that starship M-drives were fusion rockets? And later versions of (Classic) Traveller changed that to grav thruster plates.captainjack23 said:
Anyay, the copy of Book 2 I've got in front of me now simply says that starships need 10Pn% of their volume in fuel for the power plant, giving four weeks of "routine operations and manuever" - and the combat rules say that "there is no restriction on the number of accelerations which can be made by a fueled ship".
far-trader
Mongoose
StephenT said:
Kind of. Yes 1st printing has M-drives as fusion torch drives, and usable as weapons (at close range, damage equal Gs, move to long range, iirc). 2nd printing dropped that but didn't really say anything about what kind of drives they were now. It wasn't until MegaTraveller iirc that they were called thrusters and made grav drives, I think.
StephenT said:
Yep. And one could still rule and imagine them as fusion torch drives with most of that fuel as reaction mass rather than magic grav drives. But then High Guard went and made it even more fantastical by reducing fuel consumption by so much that there was obviously no reaction mass and it had to be some magic reactionless thruster that only needed power.
Out of curiosity, how does Mongoose Traveller handle it?
captainjack23
Cosmic Mongoose
far-trader said:
I think they are somewhat more than the HG levels, but still notably less than than CT.
I also think you are correct about HG being a big cause for the need for magic thrusty stuff, which were detailed unecessarily in MT.
Still, HG explicitly includes the LBB2 drives...I always looked at the current differences between military and civilian ships - the HG drives are the metaphorical equiv. of the Nuke powered navy warships - power plants you install if money or profit is less of an issue than space or effectiveness in combat; and they embody technology that is limited to government ownership. Unfortunately, the costs don't support that, but that's an easier handwave.
captainjack23 said:
If you detect it within 1 million km of the world (well beyond the 100 diameter jump limit that most traffic will be found in), then that 6 seconds is also the time from detection to impact.
If you are patrolling in Jupiter's Orbit to detect Earthbound objects in time to intercept them, the odds that an Earth bound object will pass within 500,000 km (maximum detection range) of you is less than 1 in 3 million. You cannot intercept what you cannot detect.
I agree that the momentum makes it unstopable in any event.
Supergamera
Mongoose
atpollard said:
I did not say that it was easy or practical, just possible. You could fill the system with detection satellites, and surround your world with gunnery and defensive platforms, and deep meson sites ready to stike at a moment's notice. You could have it, but it would not be a Traveller universe that would be fun to travel in.
I just tried simulating this in Gravity Simulator... and it's rather amusing.
I set up the Sun, Earth at 1 AU, and a 200 ton, 50m radius rock at 40 AU. I set the rock going in at a constant acceleration of 1G always toward the planet (so that if it misses the planet it accelerates back toward it to try again. It's basically like it has a 1G M-drive on the exact opposite side of the rock that kicks in as soon as it misses its target)
Yeah. It keeps missing
. I think it's largely due to the asteroid's and the target planet's orbital motion around the sun.
This is what it looks like after 7 years. The blue orbit is the Earth, the pink lines are the asteroid's path as it tries to hit Earth. As you can see, it's not having much luck
Now, maybe one could argue that as the rock is coming in you'd be doing lots of fine-tuning of the trajectory, but you're doing that at quite the ridiculous speed and making exquisitely tiny angular adjustments to the path of a 200,000 kg rock... (and this is completely ignoring any gravitational tweaks to the path from planets further out too). So it's not something you'd just set on "fire and forget".
I set up the Sun, Earth at 1 AU, and a 200 ton, 50m radius rock at 40 AU. I set the rock going in at a constant acceleration of 1G always toward the planet (so that if it misses the planet it accelerates back toward it to try again. It's basically like it has a 1G M-drive on the exact opposite side of the rock that kicks in as soon as it misses its target)
Yeah. It keeps missing
. I think it's largely due to the asteroid's and the target planet's orbital motion around the sun.
This is what it looks like after 7 years. The blue orbit is the Earth, the pink lines are the asteroid's path as it tries to hit Earth. As you can see, it's not having much luck
Now, maybe one could argue that as the rock is coming in you'd be doing lots of fine-tuning of the trajectory, but you're doing that at quite the ridiculous speed and making exquisitely tiny angular adjustments to the path of a 200,000 kg rock... (and this is completely ignoring any gravitational tweaks to the path from planets further out too). So it's not something you'd just set on "fire and forget".
far-trader
Mongoose
So you keep missing because you're aiming where the target is instead of where it will be when you get there. That's what's going on isn't it? Basically you're not leading your target when aiming.
far-trader said:
Basically yes. But at each timestep of the calculation (1 timestep = 32 seconds) it's always aiming the rock where the target is at that moment in time - whether it's 5 AU away or 10,000 km away. So in this case anyway, it should be adjusting its course continually... and it's still missing.
lastbesthope
Mongoose
If you're ever going to hit it you either need to increase the bandwidth of your acceleration adjustment, or factor in a Proportional Navigation guidance system.
LBH, doer of hard sums to do with spaceflight mechanics and guided weapons
LBH, doer of hard sums to do with spaceflight mechanics and guided weapons
lastbesthope
Mongoose
See this is why I get paid to do the hard sums :lol:
Proportional Navigation is a way to make sure you're aiming where the target is going by always the line of sight to the target on the same heading.
http://en.wikipedia.org/wiki/Proportional_navigation
LBH
Proportional Navigation is a way to make sure you're aiming where the target is going by always the line of sight to the target on the same heading.
http://en.wikipedia.org/wiki/Proportional_navigation
LBH
