Wedge sizes

I am constantly amused by the way things like this arise constantly in discussions of Honorverse tech: the sublime confidence that 2000 years of technology can erase or overcome fundamental characteristics of the universe. In this case, no possible advance can overcome a fundamental limit of physical optics. Build it in the '70s or build it two millennia from now, a 2m telescope will have the same resolution. And the same light-gathering power, which is a major consideration in this case. [this is minor compared to one proposal i recall being advanced many years ago, which in effect required that 'technical progress' insert new elements in the periodic table. between known elements.]

Yes, an SD wedge subtends an angle of 4 arcsec at 1 lm - I made those calculations as preparation for that post. The problem is that in order to measure that angle you need to identify both edges of the wedge. And, as I said, unless you have maneuvered specifically to do that the odds of having a suitable set of objects in the field of view are negligible. When you do have them, in order to translate angular width into the linear dimension of the wedge you _must_ know its orientation WRT your line of sight and its distance from you. Get either of those off by 10%, and you can't tell the difference between a freighter and a cruiser.

Once you get close enough, yep, it's a trivial exercise, but at that point you're going to be too freaking close for the answer to do you any good anyway.

drinksmuchcoffee wrote:
... just doing a back-of-the-envelope calculations, an SD impeller wedge at one light minute would be about four arc-seconds across. Given that the Hubble Space Telescope has an angular resolution of 0.05 arc-seconds, I'd suspect that given two thousand years of technological advancement you'd be able to see the occultation an impeller wedge would cause fairly well at such a range.

Louis R wrote:I am constantly amused by the way things like this arise constantly in discussions of Honorverse tech: the sublime confidence that 2000 years of technology can erase or overcome fundamental characteristics of the universe. In this case, no possible advance can overcome a fundamental limit of physical optics. Build it in the '70s or build it two millennia from now, a 2m telescope will have the same resolution. And the same light-gathering power, which is a major consideration in this case. [this is minor compared to one proposal i recall being advanced many years ago, which in effect required that 'technical progress' insert new elements in the periodic table. between known elements.]

Yes, an SD wedge subtends an angle of 4 arcsec at 1 lm - I made those calculations as preparation for that post. The problem is that in order to measure that angle you need to identify both edges of the wedge. And, as I said, unless you have maneuvered specifically to do that the odds of having a suitable set of objects in the field of view are negligible. When you do have them, in order to translate angular width into the linear dimension of the wedge you _must_ know its orientation WRT your line of sight and its distance from you. Get either of those off by 10%, and you can't tell the difference between a freighter and a cruiser.

Once you get close enough, yep, it's a trivial exercise, but at that point you're going to be too freaking close for the answer to do you any good anyway.

...

These starships are quite large, and it would be plausible to have several four meter optical telescopes even on a DD without taking up too much room.

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.

With respect to the orientation of the wedge, you do have some additional information -- you know the wedge is square and you also know its velocity. That limits the degrees of freedom quite a bit. If you can look at a given wedge with recon drones from a couple of different directions I'm pretty sure you can figure out the wedge size.

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.

Another way to look at it: if your impeller wedge is moving (which they almost always are) once they occult a star all you need to know is how long the star was occulted from your position (and since you know the velocity) you would get at least a rough estimate of the length of its wedge. Since the wedge is square once you know the length you know its size.

Yes, there are some pathological cases (mainly where the wedge in question is coming directly towards or away from you or where the sidewalls are facing directly towards you) where those techniques won't work -- that's why it would help immensely to look at the wedge from several different angles.

Pardon me for my ignorance but, having read some of the posts on this topic I have a confession to make. I thought the Wedge Shape was rectangular not square.

Could someone try & explain this to me?

P.S By the way on a related subject I have noticed from the pictures in House of Steel that the bow & stern hammerheads are not identical. Now I can understand that for pod layers but I was wondering whether there was a practical reason for other ships or whether it was there purely for cosmetic reasons.

Answers anyone?

Rincewind wrote:Pardon me for my ignorance but, having read some of the posts on this topic I have a confession to make. I thought the Wedge Shape was rectangular not square.

Could someone try & explain this to me?

P.S By the way on a related subject I have noticed from the pictures in House of Steel that the bow & stern hammerheads are not identical. Now I can understand that for pod layers but I was wondering whether there was a practical reason for other ships or whether it was there purely for cosmetic reasons.

Answers anyone?

Many of us thought wedges were rectangular, or at least not perfect squares. And there was enough confusion, and/or contrary evidence Maxx took the question up with other Bu9 guys to get us this information.

This info from Maxx was spawned off another thread, can't recall exactly which one, but it was definitely something about wedges. Or it got derailed into something about wedges anyways.. a frequent problem on this forum, threads getting derailed.

Rincewind wrote:P.S By the way on a related subject I have noticed from the pictures in House of Steel that the bow & stern hammerheads are not identical. Now I can understand that for pod layers but I was wondering whether there was a practical reason for other ships or whether it was there purely for cosmetic reasons.

Answers anyone?

I'm not sure. Even the 3D renders Maxxq did seems to show dissimilarities between the fore and aft hammerheads (though don't look quite like the hammerheads on the 2D line drawing in HoS).

At first thought I'd expect them to be pretty similar, since every example I can think off (pre-pod) carried the same weapons and point defense fore and aft. Maybe more sensors forward? (They'd have the best view - with the widest wedge opening, and no sidewall to get in the way)

You'd also need the same particle and rad screening on each end since you flip over to decelerate; so on most flight profiles spend at least as much time an n-space flying 'backwards' as 'forwards'; and at the same speed ranges...


So I'm failing to think of reasons you might be forced to have dissimilar shapes. (And if there aren't actually aren't any then we'd seem to be left with cosmetic or stylistic reasons)

Louis R wrote:... In this case, no possible advance can overcome a fundamental limit of physical optics. Build it in the '70s or build it two millennia from now, a 2m telescope will have the same resolution...

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 must be missing something important because from what I have worked out it should be fairly straightforward to estimate wedge size out to 10 light-minutes or possibly more. That means the Lorelei decoys probably can't work, and that Admiral Harrington's tactics at Fourth Yeltsin also probably couldn't work. So obviously I am missing something important.

drinksmuchcoffee wrote:

Louis R wrote:... In this case, no possible advance can overcome a fundamental limit of physical optics. Build it in the '70s or build it two millennia from now, a 2m telescope will have the same resolution...

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.

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 must be missing something important because from what I have worked out it should be fairly straightforward to estimate wedge size out to 10 light-minutes or possibly more. That means the Lorelei decoys probably can't work, and that Admiral Harrington's tactics at Fourth Yeltsin also probably couldn't work. So obviously I am missing something important.

Or it's possible to (at, presumably, some cost to acceleration and efficient) over-size your wedge and appear larger than your "correct" size.

Heck ships and decoys might routinely mount grav emitters just to spread low power "panels" out past the edges of the wedge to mimic it's optical signature.


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)...

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.

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.