Wedge sizes

Weird Harold wrote:

drinksmuchcoffee wrote:Recon drones in the Honorverse (at least Ghost Rider recon drones) can read ship's names off of their hulls from 10000 km. If the feature size on the ship's names is around 1m (which implies that the text itself is approximately 10 meters high) that works out to a resolving power for Ghost Rider drones of about 0.02 arc-seconds. Obviously recon drones have optics bigger than the Hubble Space Telescope on board.

I think it's more obvious that Ghost rider drones don't have physical optics. I suspect they have gravitic lenses similar to the improved grav-lensing of the Mk-16's Mod-E1 and Mod-G.

It is also possible that multiple drones can work together (like an Apollo ACM's brood) to get finer resolution.

In Shadow of Saganami there is mention of a "small" grav-lensed optical telescope in one of the observation blisters. But we really don't know from the textev how large or small such a device would be in absolute terms. My own guess is that they wouldn't be dramatically smaller than optical telescopes. The tradeoffs between field-of-view, resolving power, and size of your objective lenses in telescopes are pretty ruthless. Some designs are more compact than others, but there isn't any case I know of where a 1mm objective lens in a given design can have the same resolving power that a 1m objective lens of a different design has. Anything that can read text (even 10m high text) at 10000km is going to be kind of bulky.

I think an interferometry solution is quite likely. But having more recon drones close to your target makes it more likely that an alert crew would notice something. So there are limits to that approach.

It is kind of a howler that grav technology is used to both bend electromagnetic radiation and also to make "explosive lenses" for fusion bombs. That's like imagining a material that could be used to make both contact lenses and used as shaped charge plastic explosives -- I sure wouldn't want to put it in my eyes.

Somtaaw wrote:

Jonathan_S wrote:Though in the specific case of Honor at 4th Yeltson the gaggle of GSN light units she had milling about in front of her few SDs probably made getting any sort of optical look at them or their wedges a much harder than usual process. (Plus the two formations were heading straight for each other at fairly high speed; so you'd have less time than normal to try to figure out someone was running a shell game on you)


It's one of those things that, once you know ships have noticeably different wedge sizes, is so obvious that everyone would use automatic optical verification of wedge size to double-check their initial ship type identification. Since nobody ever does that in the books there (logically) must be some reason that the simple obvious measure doesn't actually work in practice (harder than we think to do, routine effective countermeasure, etc)...

And in the same battle, Rear Admiral Mark Brentworth took his battlecruiser squadron and somehow had his decoys deployed to mimic full superdreadnoughts, when Honor sicced him on Theisman. That's one HELL of a signal and wedge strength increase over the battlecruisers they'd normally be mimicing, and he did that well before Ghost Rider was even in the test phase. So far as I can tell, the earliest possible advances from Ghost Rider (decoys, early MDMs and the like) started testing in 1911 or so, and Fourth Yeltsin was 1909.

That means that the decoys were capacitor fed, and that he'd have to cycle dozens of them over the hour or so it was going to take to chase Theisman all the way to the hyper limit. And since Ghost Rider was also responsible for Dragon's Teeth, and later Lorelei, the decoy's were clearly also using a much lower quality of signal emitter, which would increase both the power drain and decrease signal emission efficiency.

Interesting. I just skimmed that bit of the battle again. Brentworth's BCs were 5.9 light minutes back - is that even close enough to have to worry about optical width measurement verification against a purportedly 300-ish km wedge?

Also while it does talk about having to rotate in replacement decoy drones, it doesn't say the drones were free flying, or self-powered (nor does it say they weren't).

It's possible that they were receiving beamed power from the BCs (and possibly tractored by them as well, as missile decoy drones normally were). You still might have limited operational life on the grav emitters; burning them out slowly by pushing enough power through them to simulate a Gryphon-class SD. That could require replacements even if they weren't relying on onboard power to create the fake drive signature...

Kizarvexis wrote:

MaxxQ wrote:Also, there was no info on wedges for missiles, pinnaces, CMs, etc.

Not so, upper limit on Pinnace is 10 km.

Mark 30 Condor-class pinnaces

Chapter 23, Shadow of Saganami
A pinnace impeller wedge was minuscule compared to that of a starship, or even a LAC, but it was still lethal to any solid structure it encountered, and contact with a larger, more powerful wedge would burn out the pinnace's nodes as catastrophically as a direct hit from a capital ship graser. Which was why Hawk-Papa-Two and Papa-Three had to be at least ten kilometers clear of any of the LACs—or each other—before the safety interlocks would allow their nodes to come fully on-line.

And that's just the safety limit, which always incorporates a buffer zone.

And for the canon size of a pinance wedge at not more than 1 kiolmeter wide, see chapter 13 of Ashes of Victory, where Tourville explains to Honeker the differences between pinances and LACs.

This topic seems to be one that comes up on a irregular basis, in many different threads:

viewtopic.php?f=1&t=8076&start=14
http://www.davidweber.net/forums/viewto ... start=2693
http://www.davidweber.net/forums/viewto ... 3&start=54

Jonathan_S wrote:Interesting. I just skimmed that bit of the battle again. Brentworth's BCs were 5.9 light minutes back - is that even close enough to have to worry about optical width measurement verification against a purportedly 300-ish km wedge?

Also while it does talk about having to rotate in replacement decoy drones, it doesn't say the drones were free flying, or self-powered (nor does it say they weren't).

It's possible that they were receiving beamed power from the BCs (and possibly tractored by them as well, as missile decoy drones normally were). You still might have limited operational life on the grav emitters; burning them out slowly by pushing enough power through them to simulate a Gryphon-class SD. That could require replacements even if they weren't relying on onboard power to create the fake drive signature...

I'd think they were free-flying, the same sort of decoy then-Citizen Commander Caslet used in Silesia, during HaE, when he charged into 3:1 odds with his Conquerer PNS Vaubon to "save" Honor's merchy. He deployed a decoy, set to emit another light cruiser signature, and slaved it to "follow" his real ship. I figure that's exactly how Brentworth setup his superdreadnought emitting decoys, slaved to "follow" the battlecruiser's that were screening them. Another decoy that was emitting rather heavily, would be the decoys Wayfarer used in the same book as Caslet, when Wayfarer was luring the PNS Kerebin away from the Artemis. Wayfarer had to continually weave in and out of the way between the Sultan battlecruiser, to exchange drones. I figure this is how Brentworth would have cycled his decoys at Fouth Yeltsin.

We have just enough evidence for the sort of debates we like on this forum, but not enough evidence to definitively nail down which manner the decoys were used.

I thought we were pirates trying to avoid being mouse-trapped by a cruiser. How big an investment in recon drones are we making, again?

I also thought I'd made it clear that a "rough idea" isn't good enough to distinguish cruisers from freighters. The numbers Maxx provided certainly wouldn't make me confident of always seeing the difference in a rough measurement, anyway.

Two technical points: VLBI depends on very accurate recording of phase and time of arrival of the signal at each receiver, then transmitting that data to a central processor for combination [and you need at least 2 more signals, with the correct angular separations, for closure] with other signals and reconstruction. Not particularly trivial at optical or even infrared wavelengths. Once detectors are comparable in size to the wavelength, phase information is lost, and you have to have clocks accurately synchronised to one part in 10^19, at frequencies of ~5e16Hz, that _stay_ synchronised regardless of the acceleration histories of your drones. If you should manage to find a detector, you still need to transmit thousands of gigabytes of data over light-speed links. Not all that big a deal, that, of course. Only takes an hour or so. Oh, yes! All of this ignores scintillation due to variations in light transmission along the lines of sight from the object to the various receivers, which in a typical solar system will introduce errors on the order of several wavelengths [AKA 1-2 micrometers]. One of the major sources of error in VLBI on Earth, as it happens. Probably about 1 chance in 5 that the image will be washed out and you'll have to repeat. Works nicely in astronomy, might be a bit awkward if you're a raider looking to avoid traps.

Also, the number of stars showing hydrogen emission lines is <<1% - a very few extremely hot stars with strong radiatively-driven winds and a few others with peculiar circumstellar environments. The number stars in the correct temperature range to show clean hydrogen-absorption spectra is also pretty small [~1%, IIRC]. The vast majority of stars have spectra sufficiently complex that you have to have an a priori estimate of red-shift to disentangle the more prominent lines and actually calculate it. Doable, but it takes time and you need fairly high-resolution spectra. Which, for a typical star, take an hour or two to collect even with 10m-class telescopes.

drinksmuchcoffee wrote:< snip >

Another approach would be to use recon drones and very long baseline interferometry which would effectively give you enormous resolving power. Solving the technical challenges with respect to practical visible-light interferometry wouldn't require suspending the laws of physics. Recon drones aren't exactly small either and could easily have a large optical telescope aboard.

< snip >

I know I don't write the books or the rules that physics follow in the books. But it is well-known in our universe that gravitational fields can frequency-shift light (I'm not sure if an impeller wedge would red-shift or blue-shift light). If you looked for hydrogen emission lines associated with nearly all stars and looked for the area where those emission lines were dramatically frequency-shifted, given enough time and looking at the wedge in question from enough angles I suspect you could estimate its size even from a few light-minutes away.

I suspect the actual discrimination is based on the gravitonial characteristics of the wedge, combined with things like acceleration (if it's accelerating faster than a freighter...), electronic signature and general behavior. I suspect that freighter wedges being single layer and warship wedge being double layer is detectable with the right gear and right range.

kzt wrote:I suspect the actual discrimination is based on the gravitationial characteristics of the wedge, combined with things like acceleration (if it's accelerating faster than a freighter...), electronic signature and general behavior. I suspect that freighter wedges being single layer and warship wedge being double layer is detectable with the right gear and right range.

I think you are probably right --> because of the bits of text in Ms. Midshipman Harrington where Santino lets the raider get an unopposed look sans wedge and bugs out, and the number of times we read about a raider going "oh sh1t" when the full military impeller switch is thrown, [button pushed or whatever] which -- I would assume means that the second wedge comes up, the sidewalls activate, and the guppy becomes a very dangerous predator. The writings seem to imply that the raiders thinking that they know what their sensors are telling them, and having those sensors go nuts when the wedge profile flips over.