First, the apology.
As you’ve noticed, this is the first thing I’ve posted this December, for which I apologize to all my readers and especially to those kind enough to pay me for posting things. To explain – well, it’s a second-order effect of our summer being-raided-by-the-Feds experience. (Details here, for anyone who didn’t get them at the time.)
You see, way back at the start of the month, we were called upon once more by the FBI, who were quite unexpectedly bringing our property back. I must reluctantly credit them for taking only four months to decide that weren’t, in fact, holding corporate networks for ransom, which by the standards of the American government is quite uncanny speed and efficiency. They even went so far as to apologize for “the inconvenience”, which was both (a) entirely unexpected and (b) possibly the most delicate euphemism imaginable for “having our goon squad smash up your house, terrorize your family, and help themselves to your stuff”. Dear friends, it was not the former which left me too slack-jawed with incoherence to make a properly sarcastic response.
As such, I have found myself spending the month going through the returned items, taking inventory and determining what will be the subject of future claims due to being obviously faulty (the two servers with large chunks of their cases broken off, for a start) or more subtly faulty now (gee, could that high abnormal sector count have anything to do with the natural antipathy of hard drives and fucking grenades), and then ensuring that they are all purified, exorcized, and mind-cleansed before being returned to use (my network does not need a case of foamy fibbie fever, thanks so much), which has taken up pretty much all of time.
And then it was Christmas, which was a timely relief from stressful reminders of bullshit.
But, yeah, that’s what I was doing this month instead of writing. Mea culpa, but at least I have some back ideas stored up for next month?
That all said, now, let’s talk about tractors. The beams, that is. This is inspired by a question a reader asked over on the Discourse:
Say, why aren’t tractors and other vector control tech used for fast atmospheric vehicles (especially aerospace cruisers)? You’ve got plenty of remass just sitting around outside, so you should only be spending fuel for the energy to run the vector control core?
But really, to answer it, I need to talk some about tractor beams in general, and so I’m going to do that.
Ultimately, tractor and pressor beams (and the hybrid torquor beams, which I’m not going to talk about extensively here but which y’all can deduce from the information on tractors and pressors) aren’t beams in the strictest sense. They’re representatives of one offshoot of vector-control technology, which is to say, non-local force transfer; the relevant engineered devices in this family acquired the moniker because an easy way to point your non-local force transfer is to heterodyne the exotic ontoeffect on top of a carrier. Hence “beam”.
(This is not the only way to do it: you can build a much simpler projector pair which, when powered on, will exert tractor/pressor effects between themselves – but only themselves. You can’t redirect the force anywhere else or otherwise point them. That makes them useless for many purposes, although if you want to build those cool-looking catamaran spaceships without physical hull connections or flying cities that don’t crush any poor schmuck who walks underneath, they’re quite useful for that.)
Rather than get into the messy internal details, I’m going to describe their effects. Basically, you can think of them as a springs-only-without-the-springs. If you lay a tractor beam on a target, it acts like a spring stretched between the projector and the target that wants to return to its natural length of zero; the further away the target gets, the harder it pulls, and ultimately it wants to pull the target right into the projector. A pressor beam, meanwhile, acts like a spring squished between the projector and the target that wants to return to its natural infinite length; the closer the target, the stronger the push, and ultimately it wants to shove the target an infinite distance away.
(Both of these phenomena are, of course, limited in range by the range of the carrier beam; if you can’t focus it on the target, you can’t project the ontotransfer. As the carrier beam disperses, the effective ontotransfer diminishes until the beam “snaps”.
Also, I am simplifying by using the projector as reference frame when I talk about the effects on the target. As with local force transfers, Newton’s Third Law is in effect: the tractor “really” pulls things together, and the pressor “really” pushes things apart. It’s just easier to talk using the projector reference frame.)
On its own, a tractor isn’t really all that useful; it has all the problems of a towrope – magnified, in space use, by the lack of a friction-providing medium – insofar as you can’t stop something moving towards you with a pull. Or, to put it simply, if you, the Enterprise, start towing a million tons of asteroid with your tractor beam, when you stop doing so, you’d better dodge before you get a million tons of assteroid, if you know what I mean.
Thus, in practice, all “tractor beams” are actually combined tractor-pressor units. The combination gives you the ability to hold things in place (along one axis): the tractor and pressor are configured so that the push-pull balances out at the intended distance. If the target moves closer, the tractor’s pull weakens and the pressor’s push strengthens, moving it back out; if the target moves further away, the pressor’s push weakens and the tractor’s pull strengthens, moving it back in.
Note that using a single tractor-pressor unit in this way only keeps the target in a fixed position along the axis of the beam. This can be useful in some scenarios, but as anyone who’s ever towed someone will know, does not stop it from fishtailing all over the place, along the other two axes in the absence of gravity. Tugs and other professional towers will thus use multiple projectors pointed at multiple tractor points in order to prevent this.
(A lot of tugs in the ‘verse have a similar layout to the nuBSG Cylon basestars, to mount three big projects at the end of the three protruding arms, thus giving them plenty of leverage and three-axis coverage.)
What’s a tractor point? Well, as I said, Newton’s Third Law applies: when you use a tractor (or a pressor), all the force you’re transmitting through it – potentially the full weight of the target – is applied to both the projector and the specific part of the target the beam is pointed at. For this reason, the projectors are generally bolted directly and heavily to the major structural members of a ship mounting them; likewise, on the other side of the equation, tractor points are heavily reinforced plates also bolted directly and heavily to the main structure, to provide places where a tractor beam can be safely pointed.
For non-barges, think of them as the equivalent to the tow hooks they fit to cars for emergencies, and important for the same reason: hulls are not designed to bear that much weight, and much like the case of the idiot who ties the tow rope around the fender, that will come right off and make a nasty mess. Hell, using weaponized tractors to rip off big strips of hull was even in vogue for a while.
Why not point the beam at the whole ship, you say?
Well, a couple of reasons. One, it’s a beam. Much like light only illuminates the surface of an object, the carrier beam only transmits the ontoeffect to the surface of the object. That’s not as bad as it sounds: obviously light doesn’t interact only with the first layer of atoms and nor does the carrier beam (another point in the design of tractor points is maximization of penetrance), but you aren’t going to force either through the entire object without deleterious effects.
And two, dispersal affects efficiency. A highly collimated carrier beam can deliver the ontoffect on target with little lossage; the wider you disperse the beam, on the other hand, the more lossage you get (the inverse square law is not your friend). The limiting case of this is the “reactionless drive” that works, essentially, by pointing this particular ontoeffect at half of the observable universe, at which point you’ve successfully achieved efficiencies that make the photon rocket look good.
So, to return at last to the question:
Say, why aren’t tractors and other vector control tech used for fast atmospheric vehicles (especially aerospace cruisers)? You’ve got plenty of remass just sitting around outside, so you should only be spending fuel for the energy to run the vector control core?
(And there is at least part of me at this point that really wants to say “the answer should now be deducible from the information given above”, but I’m not that mean, and besides, it’s Christmas.)
Well, there are some applications that are used, such as using tractor tethers to swap momentum (seen here) or turn corners more quickly by club-hauling against fixed tractor points; and other related effects, such as using the distinct paragravitational family of vector-control effects to, for example, build magnetogravitic jets with no moving parts. But as for main-drive effects:
- You can’t push off things, because they suffer your weight. If you use a downward-pointing pressor to keep your aircar up, everything underneath you gets crushed, and very little of it was built to be run over by an aircar. This includes all aircars using lower altitudes.
- You can’t pull on things either, because they too suffer from your weight. The club-haul grapple turn looks cool when you pull it off, but it looks less cool when you yank the coffee shop on the corner and all its patrons into the middle of the street trying it.
- You can’t fix either of those by dispersing the beam, since the same inverse-square phenomenon that reduces the harmful effects also murders your efficiency to death.
- Air (presumably the remass in question?) isn’t very motivatable by tractor-pressor technology, because it’s not solid and as such sucks at intercepting the carrier beam. (We’ve seen hand tractors being used in air before, I believe.) Tractor-pressors _do_ lose some efficiency in air – and create some minor draughts, if sufficiently powerful – because of the fraction of the beam that is intercepted, but much like shining a beam of light through air, it’s a tiny fraction. (Dust particles or water droplets can intercept it, though, so if you are in a filthy place or it’s foggy, be prepared to keep wiping the projector lens off.)
In short, you’re better off using other bits of the vector-control family for propulsion, like the basic mass-twiddling, and paragravitational widgetry like the magnetogravitic jet/pump.
Speaking of aerospace cruisers, though, consider the later designs where, given the translocation rings allowing easy back-and-forth transit, they simply keep most of the ship in orbit and use tractor technology to lower the entire flight deck into atmo…