Wedge sizes

That's it in a nutshell. The only practical way to guarantee measurement of a wedge perimeter is to silhouette it against a system body big enough to show a disk bigger than the wedge in your optical system. An unusually rich star field would also work, but basically that means the Milky Way itself. And for large swaths of that, the precision of your measurements would have to be inconveniently high to get it right.

drinksmuchcoffee wrote:

Jonathan_S wrote:
...

But I'd hope at least some pirates would be paranoid enough to attempt to confirm their target identification by cross checking the wedge size against the presumed ship type once they could get a good optical view of it. Especially since that's a free data-point, unlike expending a recon drone to eyeball the target.

We know warships tend to keep their wedge between them and the pirate to prevent them from seeing the hamerheads; so you'd think that would let the pirate measure how many degrees of view the wedge'd width was taking up - combine that with the range, which they'd know from grav sensors, and it's trivial math to calculate the wedge's size.

Something 70+ km smaller than you'd expect in even a small freighter should be a clue that something's not right.

You'd have to be a lot closer to the ship to do this than to measure wedge power; but I'd think you'd be able to do it from outside SDM range. (Though quite possible not before you'd built up too large a vector to break clear and evade the warship)

How do you see an impeller wedge?

I always imagined an impeller wedge was black. It doesn't seem obvious that it would radiate EM energy in any significant amount correlated to the wedge area. And if an impeller wedge is black you can't really "see" it in space unless it is occulting something else. Since space is mostly empty that will make it rather challenging to estimate wedge size at any reasonable range.

looks like what you have is a broken power law: the exponent changes value at least once.

plotting it on a [iirc] log-log scale will produce straight lines with slope = exponent - and show a knee where the exponent changes.

Jonathan_S wrote:Initial eyeball looks like the LACs are slightly off line. Might play with removing them.

drinksmuchcoffee wrote:

Jonathan_S wrote:
...

But I'd hope at least some pirates would be paranoid enough to attempt to confirm their target identification by cross checking the wedge size against the presumed ship type once they could get a good optical view of it. Especially since that's a free data-point, unlike expending a recon drone to eyeball the target.

We know warships tend to keep their wedge between them and the pirate to prevent them from seeing the hamerheads; so you'd think that would let the pirate measure how many degrees of view the wedge'd width was taking up - combine that with the range, which they'd know from grav sensors, and it's trivial math to calculate the wedge's size.

Something 70+ km smaller than you'd expect in even a small freighter should be a clue that something's not right.

You'd have to be a lot closer to the ship to do this than to measure wedge power; but I'd think you'd be able to do it from outside SDM range. (Though quite possible not before you'd built up too large a vector to break clear and evade the warship)

How do you see an impeller wedge?

I always imagined an impeller wedge was black. It doesn't seem obvious that it would radiate EM energy in any significant amount correlated to the wedge area. And if an impeller wedge is black you can't really "see" it in space unless it is occulting something else. Since space is mostly empty that will make it rather challenging to estimate wedge size at any reasonable range.

I'm not sure exactly what an impeller wedge would look like, but they are visible in normal space:

The Honor of the Queen, Chapter 5 wrote:“Engineering, Commander Higgins.”
“Reconfigure to impeller drive, please, Mr. Higgins.”
“Aye, aye, Ma’am. Reconfiguring now,” Higgins acknowledged, and Fearless folded her Warshawski sails into her impeller wedge.
There was no internal sign of the change, but Honor’s engineering readouts and visual display told the tale. Unlike Warshawski sails, which were invisible in normal space except for the brief moment in which they radiated the energy bleed of a translation, the stressed gravity bands of an impeller drive were almost painfully obvious. Now they sprang into existence above and below Fearless, angled towards one another in a wedge open both ahead and astern, and stars red-shifted as a gravity differential of a hundred thousand MPS2 grabbed at their photons. The cruiser floated within her wedge, like a surfer poised in the curl of a wave which hadn’t yet begun to move, and Honor watched her communications officer.

Italics are the author's, boldface and underlined text is my emphasis.

Louis R wrote:That's it in a nutshell. The only practical way to guarantee measurement of a wedge perimeter is to silhouette it against a system body big enough to show a disk bigger than the wedge in your optical system. An unusually rich star field would also work, but basically that means the Milky Way itself. And for large swaths of that, the precision of your measurements would have to be inconveniently high to get it right.

... 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.

If the wedge frequency-shifts or polarizes the light passing through it in an exotic way, that is probably more easily detectable than the straight-up occultation effect.

Cool fact. At 400k kilometers (approximately the distance from the earth to the moon) an SD wedge has about 1/10 the angular size of the moon. So you'd be able to see a wedge with the naked at at that range and quite a bit further in many cases.

Louis R wrote:looks like what you have is a broken power law: the exponent changes value at least once.

plotting it on a [iirc] log-log scale will produce straight lines with slope = exponent - and show a knee where the exponent changes.

Jonathan_S wrote:Initial eyeball looks like the LACs are slightly off line. Might play with removing them.

Could be. I'm not even sure how to dig into what Open Office Calc's trend lines are. I just cycled through the auto options (linear, logarithmic, power, etc) and that was the best fit.

But then I didn't get a chance to dig any deeper.

drinksmuchcoffee wrote:...

Cool fact. At 400k kilometers (approximately the distance from the earth to the moon) an SD wedge has about 1/10 the angular size of the moon. So you'd be able to see a wedge with the naked at at that range and quite a bit further in many cases.

I looked it up.

The human eye has an angular resolution of about an arc-minute. So you could see that SD-sized impeller wedge out to a little over a million km.

drinksmuchcoffee wrote:If the wedge frequency-shifts or polarizes the light passing through it in an exotic way, that is probably more easily detectable than the straight-up occultation effect.

From the description of what a wedge looks like from inside -- redshifting stars, etc -- I would guess a wedge is transparent in the way old glass is transparent. Since a military wedge is double layered, It probably looks like a like the transparent version of a fun-house mirror. Everything beyond would be visible, but displaced sort of randomly. Kind of like trying to map a river bottom in a rapids.

I think the edges would be detectable if you're looking for them, but that might depend on the background. If there is a fairly dense background, the edges might show a line of doubled stars -- much like the line in old-fashioned bifocal glasses.

Louis R wrote:looks like what you have is a broken power law: the exponent changes value at least once.

plotting it on a [iirc] log-log scale will produce straight lines with slope = exponent - and show a knee where the exponent changes.

Jonathan_S wrote:Initial eyeball looks like the LACs are slightly off line. Might play with removing them.

If you look closely at the smaller ships, one can distinctly see at least two different equations at work. Seems to be three equations when broken into age of the ship in question. This will utterly destroy any curve fit. It would appear that a scaler component equating to compensator efficiency is at work. Likewise there is a limiting factor for "FAT" ships. BCP, CLAC, CARAVAN. ... I am wondering if the NIKE BCL is a mistake? Though if I label the BCP as a "FAT" ship it could work while removing older ships and only use more modern ships, Culverin, Roland, SAG-B/C etc, it fits.

One wedge/tonnage that does not fit is the Edward Saganami. It fits no curve. Remove it.

REGARDING "FAT" ships:
I would have expected the "FAT" ships, to require a larger wedge for their tonnage. (Less efficient) Instead we see that "FAT" ships have a smaller wedge for their tonnage in comparison... I wonder if someone forgot to invert the fraction...

PS> If you flip your graph with tonnage on the Y-axis you get a nice simple power equation curve... Make sure to break out the old ships from the new.

drinksmuchcoffee wrote:

drinksmuchcoffee wrote:...

Cool fact. At 400k kilometers (approximately the distance from the earth to the moon) an SD wedge has about 1/10 the angular size of the moon. So you'd be able to see a wedge with the naked at at that range and quite a bit further in many cases.

I looked it up.

The human eye has an angular resolution of about an arc-minute. So you could see that SD-sized impeller wedge out to a little over a million km.

Well, I not sure that that's quite right. If you had two SD's seperated by the wedge size [or maybe twice that distance] - then you could just about 'see' that there are actually 2SD's there. You could see something is there for much further. Resolution is not the same as detection!

isaac_newton wrote:

drinksmuchcoffee wrote:...
I looked it up.

The human eye has an angular resolution of about an arc-minute. So you could see that SD-sized impeller wedge out to a little over a million km.

Well, I not sure that that's quite right. If you had two SD's seperated by the wedge size [or maybe twice that distance] - then you could just about 'see' that there are actually 2SD's there. You could see something is there for much further. Resolution is not the same as detection!

Very true.

Please keep in mind those were back-of-the envelope calculations. I'm pretty sure an unaided human eye could easily see (or rather see the occultation caused by) an impeller wedge of a large starship at 500000 km or less. Under very optimum conditions you might be able to see one out to 10 million km or so.

Also remember you are looking at something that is essentially black on a black background. That is going to make one hard to see under the best of circumstances, unless it is in front of a nearby moon.