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Fall 1924: What will the Admiralty build next

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Re: Fall 1924: What will the Admiralty build next
Post by tlb   » Thu Jun 16, 2022 2:17 pm

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phillies wrote:The question is: A ship moving at constant acceleration is no harder to hit than a ship that is stationary. 600 gees is 6000 m/s^2meaning in ten seconds the ship changes its position by 300 kilometers relative to no acceleration.How fast can a ship change its acceleration? Also, the ship must accelerate in the direction its wedge is pointing. How rapidly can that direction be changed?

ThinksMarkedly wrote:Sufficiently fast, apparently. We know that slewing the wedge is possible because that's how ships turn and that it's faster than turning with thrusters, so even if you can only accelerate 600 gravities in one direction, you do have some perpendicular acceleration possible, which would change the direction of your main acceleration vector.

The ship doesn't need to move at 100% acceleration all the time either, though that is only a useful trick if it's performing a zig-zag course in the first place. If it's coming roughly straight at the beam emitter, changing the amplitude of the acceleration vector doesn't help evading the beam.

Also the ship does not need to move too far in a direction perpendicular to the beam to generate a miss, considering that the width of the beam will still be about aperture size. Further RFC has stated that it is possible for a ship to move around within the wedge, making it more difficult to achieve a hit.
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Re: Fall 1924: What will the Admiralty build next
Post by Relax   » Thu Jun 23, 2022 9:02 am

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ThinksMarkedly wrote:
Relax wrote: If one adds up the tonnages, an RD + Laser head =~1st havenite war large missiles or probably equivalent to the Cataphract III C's the malign is building. So what if they are slightly slower to arrive when launched from an RD? They are still coming in at 0.8C and with the RD's stealth cannot be seen, localized, and destroyed until ~300,000km from ANYONE's sensors(often 10X less in the books aka laser head range). This means NO ECM, and NO CM's can attack them as only PDLC's are worth a damn as they do not even know they are coming other than pure logic that yes, the potential enemy will attack/defend.


They're NOT slightly slower. An RD is as slow as missile from Travis' time: 3500 gravities. It takes nearly 2 hours for one of those to get to 0.8c... and 46 light-minutes on a straight line. A more realistic scenario is 10 to 12 light-minutes range, which is the distance from a planet to the hyperlimit... but that increases the speed to about 0.4c.


Sorry for delay, but had a child. :o :D Well, not me personally... :twisted: Will not be posting much for a while... Do not have the time, but said I would reply to folks and did not.

Not to you Thinky just to everyone really. Not sure why anyone thinks the RD should die with laser head, etc attached. No reason for it to do so. I always had a problem with that in the books in AAC when I first read it. I was scratching my head going, uh, what kind of idiot engineer would throw away a perfectly good RD when you can just toss the laser head forward with a tiny ancient chemical rocket motor, turn the RD around and skedaddle.

Big ol'...???? More of a NIT: where did you pull 3500g from? Nowhere in the books. We have a 10,000G under perfect stealth figure and higher if no stealth is maintained. How much higher, we have no idea. This rather drastically decreases time required.

Now back to Louise. Gah, poor kid, but wifey wanted Louise... ugg My bet is she will be known by her middle name.
_________
Tally Ho!
Relax
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Re: Fall 1924: What will the Admiralty build next
Post by Theemile   » Thu Jun 23, 2022 9:19 am

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Relax wrote:
Sorry for delay, but had a child. :o :D Well, not me personally... :twisted: Will not be posting much for a while... Do not have the time, but said I would reply to folks and did not.

Not to you Thinky just to everyone really. Not sure why anyone thinks the RD should die with laser head, etc attached. No reason for it to do so. I always had a problem with that in the books in AAC when I first read it. I was scratching my head going, uh, what kind of idiot engineer would throw away a perfectly good RD when you can just toss the laser head forward with a tiny ancient chemical rocket motor, turn the RD around and skedaddle.

Big ol'...???? More of a NIT: where did you pull 3500g from? Nowhere in the books. We have a 10,000G under perfect stealth figure and higher if no stealth is maintained. How much higher, we have no idea. This rather drastically decreases time required.

Now back to Louise. Gah, poor kid, but wifey wanted Louise... ugg My bet is she will be known by her middle name.


Congrats Relax - A Round of Virtual Stogies on me!

Wasn't the 3500 Gs the limit on the RD used to scope out Monica with the Copenhagen? They might have done that for endurance purposes. The whole time/limitation thing in Monica seems silly given what we've seen elsewhere. Another example of Plot driving the need - not consistent tech limitations probably.

Having a separate warhead isn't consistant with the current hardware we're seeing, but sure is possible - it might be too large to fit in the standard RD body, or might compromise an aspect of the stealth - but those are just engineering issues - technically you are completely correct, it is possible - just the only iterations we're seeing in the story have integrated warheads.
******
RFC said "refitting a Beowulfan SD to Manticoran standards would be just as difficult as refitting a standard SLN SD to those standards. In other words, it would be cheaper and faster to build new ships."
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Re: Fall 1924: What will the Admiralty build next
Post by Jonathan_S   » Thu Jun 23, 2022 9:47 am

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Relax wrote:Big ol'...???? More of a NIT: where did you pull 3500g from? Nowhere in the books. We have a 10,000G under perfect stealth figure and higher if no stealth is maintained. How much higher, we have no idea. This rather drastically decreases time required.

Fastest I recall seeing Ghost Rider drones moving was 10,000 gravities -- but there was no mention that they were being stealthy.
Shadow of Victory wrote:TG 10.2.9’s velocity was up to only 1,500 KPS while the Ghost Rider drones sped ahead of them at 10,000 gravities. He wanted those birds up forward to give him as close a look as possible at what CIC was calling eight battlecruisers and eight destroyers, 104,808,572 kilometers ahead of them
(OTOH the text is silent on whether or not Admiral Tamaguchi's SLN force actually saw them)

The stealthy accel we saw was half that
Storm from the Shadows wrote:Ghost Rider platforms, loping along at the low (for them) acceleration of only five thousand gravities in order to stay stealthy
And note that that was remaining stealthy at about 4 light-minutes from the target. I'd suspect that accel would need to be further reduced as you got closer to avoid having the wedge's growing signal burn through the drone's stealth.
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Re: Fall 1924: What will the Admiralty build next
Post by drothgery   » Thu Jun 23, 2022 1:12 pm

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Relax wrote:Sorry for delay, but had a child. :o :D Well, not me personally... :twisted: Will not be posting much for a while... Do not have the time, but said I would reply to folks and did not.

If anyone was wondering why I've posted a lot less since about April of 2020 (little guy's two and change now; not sure where the time went) ... :D
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Re: Fall 1924: What will the Admiralty build next
Post by Theemile   » Thu Jun 23, 2022 2:20 pm

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drothgery wrote:
Relax wrote:Sorry for delay, but had a child. :o :D Well, not me personally... :twisted: Will not be posting much for a while... Do not have the time, but said I would reply to folks and did not.

If anyone was wondering why I've posted a lot less since about April of 2020 (little guy's two and change now; not sure where the time went) ... :D


Well, another virtual Stogie round on me

Man, the virtual smoke is getting thick in here - will someone open another browser window?
******
RFC said "refitting a Beowulfan SD to Manticoran standards would be just as difficult as refitting a standard SLN SD to those standards. In other words, it would be cheaper and faster to build new ships."
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Re: Fall 1924: What will the Admiralty build next
Post by kzt   » Thu Jun 23, 2022 5:04 pm

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phillies wrote:The question is: A ship moving at constant acceleration is no harder to hit than a ship that is stationary. 600 gees is 6000 m/s^2meaning in ten seconds the ship changes its position by 300 kilometers relative to no acceleration.How fast can a ship change its acceleration? Also, the ship must accelerate in the direction its wedge is pointing. How rapidly can that direction be changed?

The evidence is that changes of acceleration is instant. Ships have gone from 0 to thousand plus g instantly.

David has talked about maneuver time and SDs have the agility and snap you'd associate with a ultra large crude carrier.
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Re: Fall 1924: What will the Admiralty build next
Post by phillies   » Thu Jun 23, 2022 6:53 pm

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tlb wrote:
phillies wrote:The question is: A ship moving at constant acceleration is no harder to hit than a ship that is stationary. 600 gees is 6000 m/s^2meaning in ten seconds the ship changes its position by 300 kilometers relative to no acceleration.How fast can a ship change its acceleration? Also, the ship must accelerate in the direction its wedge is pointing. How rapidly can that direction be changed?

ThinksMarkedly wrote:Sufficiently fast, apparently. We know that slewing the wedge is possible because that's how ships turn and that it's faster than turning with thrusters, so even if you can only accelerate 600 gravities in one direction, you do have some perpendicular acceleration possible, which would change the direction of your main acceleration vector.

The ship doesn't need to move at 100% acceleration all the time either, though that is only a useful trick if it's performing a zig-zag course in the first place. If it's coming roughly straight at the beam emitter, changing the amplitude of the acceleration vector doesn't help evading the beam.

Also the ship does not need to move too far in a direction perpendicular to the beam to generate a miss, considering that the width of the beam will still be about aperture size. Further RFC has stated that it is possible for a ship to move around within the wedge, making it more difficult to achieve a hit.


Not exactly. There is a target area within which the ship could possibly be, given its acceleration, so if you fire randomly within that area, you might hit. By accelerating sideways, the ship might accelerate into the grazer beam.
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Re: Fall 1924: What will the Admiralty build next
Post by tlb   » Thu Jun 23, 2022 7:18 pm

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tlb wrote:Also the ship does not need to move too far in a direction perpendicular to the beam to generate a miss, considering that the width of the beam will still be about aperture size. Further RFC has stated that it is possible for a ship to move around within the wedge, making it more difficult to achieve a hit.

phillies wrote:Not exactly. There is a target area within which the ship could possibly be, given its acceleration, so if you fire randomly within that area, you might hit. By accelerating sideways, the ship might accelerate into the grazer beam.

It is true that you could move into the beam, but you also move farther away.

Here is the quote from RFC; I will stand by what I wrote based on my reading what he said:
In addition, a ship can shift position somewhat within the area of its wedge. One can predict exactly where a ship will be within the volume of its wedge if it is seeking to attain the maximum possible acceleration (assuming that one has solid, reliable numbers on its inertial compensator's performance envelope), but at lower accelerations, ships can move "off center" within their wedges.

Wedge Geometry
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Re: Fall 1924: What will the Admiralty build next
Post by Somtaaw   » Fri Jun 24, 2022 1:34 pm

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Jonathan_S wrote:Fastest I recall seeing Ghost Rider drones moving was 10,000 gravities -- but there was no mention that they were being stealthy.
Shadow of Victory wrote:TG 10.2.9’s velocity was up to only 1,500 KPS while the Ghost Rider drones sped ahead of them at 10,000 gravities. He wanted those birds up forward to give him as close a look as possible at what CIC was calling eight battlecruisers and eight destroyers, 104,808,572 kilometers ahead of them
(OTOH the text is silent on whether or not Admiral Tamaguchi's SLN force actually saw them)

The stealthy accel we saw was half that
Storm from the Shadows wrote:Ghost Rider platforms, loping along at the low (for them) acceleration of only five thousand gravities in order to stay stealthy
And note that that was remaining stealthy at about 4 light-minutes from the target. I'd suspect that accel would need to be further reduced as you got closer to avoid having the wedge's growing signal burn through the drone's stealth.


We... well you, calculated faster than that in a prior discussion I recall. When Terekhov came smashing over the wall, and "talked" the local SLN destroyers into surrendering in Mobius.

Shadow of Freedom Ch 30 wrote:“CIC makes it thirteen sources, Sir,” the lieutenant reported after a moment, and Hammond felt his muscles tighten. “They’re half a light-minute outside the hyper limit,” Garrett continued. “That puts them at a range of two-one-five-point-nine million klicks. Current closing velocity niner-one-three KPS. Acceleration five-point-seven KPS squared.”
-minor Solly question about IDs-
“We won’t have anything lightspeed for another twelve minutes or so, Sir,” Garrett replied in a curiously flat voice. “But from the footprints, CIC is calling it twelve cruisers…and a superdreadnought.”
-snip-
“Anything from them?” Commander Tremont Watson demanded as he strode explosively onto Oceanus’ bridge.

“No, Sir.” Lieutenant Branston Shang, the light cruiser’s communications officer, had managed to beat the CO to the command deck. Now he looked over his shoulder at Watson and shook his head. “Given the range, there won’t be for at least another three minutes, even assuming they know we’re here to be transmitting to, Sir,” he added respectfully.
-snip-
“Not really, Skipper.” Hammond shrugged unhappily. “They only made their alpha translation nine minutes ago, so we still don’t have any lightspeed confirmation, but CIC’s confident about their mass estimates and wedge strengths.”
-snip and jump to Manty POV-
“How much longer for the platforms to give us a good look at the planetary orbitals, Stilt?” he asked.

“Not long, Sir,” his operations officer replied. “They’re only about ninety-six light-seconds from Mobius Beta, now. In fact, if there’s anything in orbit with active impellers, it’s got to be on the far side of the planet from us at the moment, or we’d already have picked it up.”
-snip-
Terekhov tipped back in his command chair, gazing at the master plot. Quentin Saint-James had reentered normal-space twenty-six minutes earlier. During that time, she’d increased her n-space velocity to just over ninety-four hundred kilometers per second and traveled just under 7.8 million kilometers towards the planet officially designated Mobius Beta. During that same interval, the Ghost Rider recon platforms they’d deployed as soon as they’d made their alpha translation had traveled ten and a half light-minutes—almost 200 million kilometers—at their vastly higher acceleration. In fact, they were already decelerating towards a zero/zero rendezvous with the planet.
-minor snip of 2 paragraphs-
“The platforms are still ninety-two light-seconds out, but we should be getting good visual in another minute or so,” the ops officer continued. “CIC is calling them destroyers for now, but—”


In ~26 minutes, the Ghost Rider drones travelled around 200 million km give or take, from a starting distance of 215.9km away from the Sollies; with the Manticoran ships having done their Alpha translation velocity with 913 kps and then accelerating at an additional 5.7kps on top of that as they were dropping the Ghost Riders.

And the Sollies never even had a clue they were less than 92 light-seconds away and still decelerating hard. In addition thanks to Terekhov 'quizzing' Ensign Zilwicki, they additionally deployed a Hermes Buoy that ALSO made the trip from the approaching Manticoran ships to the Sollies at high acceleration and wasn't noticed either.

Edit: 92 light-seconds is just a hair over 27.6 million km, so correction the Ghost Rider drones travelled almost exactly 200 million km in 26 minutes because they were decelerating to bleed off the speed Terekhov brought over the wall with him to match orbits with Mobius itself. But they made the full 200km plus without anybody having a sniff of them, as did the Hermes Buoy.

Edit 2: according to an acceleration calculator, 200milllion km travelled, initial speed of 913 kps and 26 minutes works out to an acceleration profile of nearly 17000 gs, although the drones were decelerating at the time, which should actually increase their speed because they had to get upto speed then turn around and slow way down; so Ghost Riders are (I think anyways) capable of between 20,000 and 30,000 gravs of acceleration with several hours of active time... or you can "pull a Henke" and leave the drones in a stationary & powered-down mode and Ghost Riders are capable of staying on station for at least 2 weeks (per her actions at New Tuscany)
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