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Dead Horses - Discussion

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Re: Dead Horses - Discussion
Post by tlb   » Fri Jan 24, 2020 8:54 am

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ThinksMarkedly wrote:I was really thinking of a light-week to a light-month out. A single light hour is within the range of most systems' hyper detection sensor net. At least, any system with strong enough defences you'd try this trick at anyway. A translation a light-hour out will be noticed within 1 minute of the ship arriving; one light-week will give 2 hours and 35 minutes until detection.
Jonathan_S wrote:And even if you're firing at a DD in orbit that's a target that's at least a couple dozen meters across on it's smallest axis. So you hardly need mm level accuracy to begin with.

You're not going to fire at a DD or any ship or anything that is moving. You could fire at mothballed ships that are in stable orbits, but an active ship, even one idling with impellers shut down could activate them and get underway in less than an hour.

So what was your planned target? I understand that forts move randomly within your time-frame. Unless you are shooting at an inhabited planet, which I doubt RFC would approve, I only see the space stations and the Blackbird Base that were targeted by Oyster Bay; or perhaps the ships that were mothballed, rather than being completed under Janacek. Since Oyster Bay could be duplicated by something like Mistletoe and that eliminates the uncertainty of traffic or other changes; why use a graser from that distance?
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Re: Dead Horses - Discussion
Post by kzt   » Fri Jan 24, 2020 10:08 am

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tlb wrote:So what was your planned target? I understand that forts move randomly within your time-frame. Unless you are shooting at an inhabited planet, which I doubt RFC would approve, I only see the space stations and the Blackbird Base that were targeted by Oyster Bay; or perhaps the ships that were mothballed, rather than being completed under Janacek. Since Oyster Bay could be duplicated by something like Mistletoe and that eliminates the uncertainty of traffic or other changes; why use a graser from that distance?

Because everyone has grasers. Lots of grasers.
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Re: Dead Horses - Discussion
Post by tlb   » Fri Jan 24, 2020 5:20 pm

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tlb wrote:So what was your planned target? I understand that forts move randomly within your time-frame. Unless you are shooting at an inhabited planet, which I doubt RFC would approve, I only see the space stations and the Blackbird Base that were targeted by Oyster Bay; or perhaps the ships that were mothballed, rather than being completed under Janacek. Since Oyster Bay could be duplicated by something like Mistletoe and that eliminates the uncertainty of traffic or other changes; why use a graser from that distance?

kzt wrote:Because everyone has grasers. Lots of grasers.

But the question still remains "why from that distance?". The other question is "what was your planned target?".

Just a reminder from what is now the second page of this thread:
kzt wrote:I’d go with “reasons”. Unless Duckk can find someone who wants to build some at least vaguly logical justification. So far the best we’ve come up with is “that isn’t how it works”, which is basically “reasons”.

It’s dead, it won’t work, but why is unknown to us. I suspect the real reason is David didn’t realize what he was creating with gamma ray lasers, but whatever, it doesn’t work.

Theemile wrote:"Due to Authorial Fiat, oversized Lasers in the Honorverse will not work against "fixed" targets at very long range and cannot be used to strike planets or stations with known trajectories. While this has been proven to be possible using modern physics, it simply is not part of the Honorverse story."
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Re: Dead Horses - Discussion
Post by ThinksMarkedly   » Fri Jan 24, 2020 11:47 pm

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tlb wrote:
tlb wrote:So what was your planned target? I understand that forts move randomly within your time-frame. Unless you are shooting at an inhabited planet, which I doubt RFC would approve, I only see the space stations and the Blackbird Base that were targeted by Oyster Bay; or perhaps the ships that were mothballed, rather than being completed under Janacek. Since Oyster Bay could be duplicated by something like Mistletoe and that eliminates the uncertainty of traffic or other changes; why use a graser from that distance?

kzt wrote:Because everyone has grasers. Lots of grasers.

But the question still remains "why from that distance?". The other question is "what was your planned target?".


I was just talking about the feasibility of this type of attack. You could fire from a light-month away and hit where you wanted to hit. Whether there's any target whose position you can accurately predict a month in advance and is worth the trouble is an entirely different matter.

Why you'd do this? Because even Mistletoe or the oversized graser torpedoes can fail or leave debris behind that could point back to you. There's nothing from the ship that fired the long-range shot left to be analysed (if you REAAAALY wanted it, you could calculate the trajectory of the graser, intercept it later and fingerprint the photons... every emitter must have specific harmonics).

The shot needs to be from far enough away that light-speed sensors couldn't be turned to the attackers' emergence point and ID the ships doing the attacking. At a light-hour away, which is inside of Saturn's orbit for us, there's probably some traffic to asteroids and outposts, and regular telescopes can be pointed at you.

At a light-day away, grav pulses arrive in 23.2 minutes. If the QRF travelled in the alpha band (which they wouldn't do), they would to cross 23.2 pseudo-light-minutes, which at 500 G they can do in 3.6 hours. Upon arriving there and finding nothing, they can just go back to hyper, overtake the photons, drop back to n-space, and observe the suspicious hyper footprint less than 4 hours old at that point. Most likely, around an hour old only. With multiple ships, from even closer.

And there goes your secrecy.

How big is a ship from a light-hour away? A 500m long x 60 m tall CA would subtend an angle of .095 x .01 milli-arcseconds. The HST today can resolve .014 arc seconds at certain wavelengths. We'd need a 1000x improvement.
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Re: Dead Horses - Discussion
Post by tlb   » Sat Jan 25, 2020 11:00 am

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ThinksMarkedly wrote:I was just talking about the feasibility of this type of attack. You could fire from a light-month away and hit where you wanted to hit. Whether there's any target whose position you can accurately predict a month in advance and is worth the trouble is an entirely different matter.

Why you'd do this? Because even Mistletoe or the oversized graser torpedoes can fail or leave debris behind that could point back to you. There's nothing from the ship that fired the long-range shot left to be analysed (if you REAAAALY wanted it, you could calculate the trajectory of the graser, intercept it later and fingerprint the photons... every emitter must have specific harmonics).

The shot needs to be from far enough away that light-speed sensors couldn't be turned to the attackers' emergence point and ID the ships doing the attacking. At a light-hour away, which is inside of Saturn's orbit for us, there's probably some traffic to asteroids and outposts, and regular telescopes can be pointed at you.

At a light-day away, grav pulses arrive in 23.2 minutes. If the QRF travelled in the alpha band (which they wouldn't do), they would to cross 23.2 pseudo-light-minutes, which at 500 G they can do in 3.6 hours. Upon arriving there and finding nothing, they can just go back to hyper, overtake the photons, drop back to n-space, and observe the suspicious hyper footprint less than 4 hours old at that point. Most likely, around an hour old only. With multiple ships, from even closer.

And there goes your secrecy.

How big is a ship from a light-hour away? A 500m long x 60 m tall CA would subtend an angle of .095 x .01 milli-arcseconds. The HST today can resolve .014 arc seconds at certain wavelengths. We'd need a 1000x improvement.

Let's see if I understand the attack whose feasibility you are trying to describe. It is an unprovoked attack on an unsuspecting nation (otherwise, why the need to keep your identity secret?).

Here is another way to preserve anonymity from only two light-days out: through secret channels, purchase an armed merchant ship similar to Captain Bachfisch's Pirates' Bane, then behind false panels on one side mount a battery of the strongest grasers that the ship can handle. Come out of hyper two light-days out broadside to the target with the sidewall up. Spend two thirds of the time needed to recycle the hyper generator in analyzing the target and computing firing coordinates and one third of the time in firing through the gunports, then fleeing back into hyperspace before any search party could get close. That givens a war crime from a much more reasonable distance while preserving your identity. The distance is dictated by the time to recycle the hyper generator, which I have guessed to be about 40 minutes; this can be adjusted so the accurate recycle time is about equal to the time to detect the hyper-footprint.
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Re: Dead Horses - Discussion
Post by ThinksMarkedly   » Sat Jan 25, 2020 11:58 am

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tlb wrote:Here is another way to preserve anonymity from only two light-days out: through secret channels, purchase an armed merchant ship similar to Captain Bachfisch's Pirates' Bane, then behind false panels on one side mount a battery of the strongest grasers that the ship can handle. Come out of hyper two light-days out broadside to the target with the sidewall up. Spend two thirds of the time needed to recycle the hyper generator in analyzing the target and computing firing coordinates and one third of the time in firing through the gunports, then fleeing back into hyperspace before any search party could get close. That givens a war crime from a much more reasonable distance while preserving your identity. The distance is dictated by the time to recycle the hyper generator, which I have guessed to be about 40 minutes; this can be adjusted so the accurate recycle time is about equal to the time to detect the hyper-footprint.


Oh, not disputing that there are better ways. I'm not even saying it's a good idea or that there are targets of value enough that can be targeted from such far position. I was merely saying that if someone really wanted to, they could.

The reason that it doesn't happen more often is probably that there are better ways, that the targets of value can't be targeted from such far away (they jink in their orbits often enough), there's too high a danger of EEV, and/or that no one wants to do this in secret.
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Re: Dead Horses - Discussion
Post by ThinksMarkedly   » Sun Jan 26, 2020 8:50 pm

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Another dead horse topic: the Imperial Manticoran Navy. Looks like RFC pretty much decided the RMN wasn't going to change names and that was that.
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Re: Sticky for Newbs - Dead Horses
Post by Loren Pechtel   » Sun Jan 26, 2020 11:12 pm

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kzt wrote:
Loren Pechtel wrote:
The thing is, you need not only your location but velocity. If you fire at a target a light-hour away you need to know your velocity relative to the target down to several meters per hour.

Why? A photon moves at C whether the emitter is at at rest or moving at .95C.


Lets say you're off by 1 meter per second in figuring your velocity. You fire at a target one light hour away--your beam is 3,600 meters away from where you intended to fire. That's a clean miss against almost anything you might want to shoot at.
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Re: Dead Horses - Discussion
Post by Loren Pechtel   » Sun Jan 26, 2020 11:16 pm

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ThinksMarkedly wrote:With enough computing power, you can integrate for more than three bodies. But even if you couldn't, you don't need to resolve for the entire star system, only for the body you're interested and other massive objects that will affect the position of your target within the margin of error.


It's not only a matter of calculation, but of measurement.
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Re: Dead Horses - Discussion
Post by Loren Pechtel   » Sun Jan 26, 2020 11:19 pm

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ThinksMarkedly wrote:How big is a ship from a light-hour away? A 500m long x 60 m tall CA would subtend an angle of .095 x .01 milli-arcseconds. The HST today can resolve .014 arc seconds at certain wavelengths. We'd need a 1000x improvement.


You just gave me a nasty thought: We are looking at beam divergence for grasers, but we aren't using gamma rays for our aiming. As you say, even the Hubble isn't even in the ballpark for resolving the target--how can you aim more accurately than you can resolve?
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