?

. . . . . . . . . . . . MEMORANDUM . . . . . . . . . . . .


TO: WDB
FROM: SONJA HEMPHILL
Re: Hybrid Impeller-Spider


PROPOSAL: Hybrid David Taylor-class Charles Ward
PLATFORM: LD


Notes:
Design also lends itself to LAC carriers and troop transports.

Jonathan_S wrote:

Galactic Sapper wrote:Alliance micro fusion generators would make grazer torpedoes much worse and potentially allow them to be scaled down as well as given much more range. The possibility of grazer torps the size of MDMs should be terrifying.

Though given the way spider drives are said to work you need size (or at least length) to get acceleration. Spider acceleration, as I understand it, is fairly dependent on the the number of ultra-powerful tractor-like spider projectors that can be mounted. So if you shrink it the already low acceleration is likely to decrease.

(Which means that if the crew could survive the acceleration, which they can't, a spider ship should be able to mount enough projectors to out accelerate the fairly sedate graser torp)

Still, microfusion would give the MAlign a nasty new toy to incorporate in their toolbox.

And given their current military mix (where their main warships seem to be ambush predators (striking unseen to survive) is probably more useful to them than FTL fire control (signals are detectable) or the MDM baffle (their missiles don't seem to be their primary weapon)

Going the other way knowledge of the Spider drive's details might let the GA become more effective at detecting it; but I can't seem them deploying any significant number of spider ships of their own. Possibly the biggest short term impact from a technology transfer would be the vastly higher accelerations of the latest Cataphract missile's drives. If they could put those into a evolution of the Mk23 it'd give their existing MDMs are significant performance boost.

Or some unholy combination of techs, such as grafting a spider drive to a pod full of missiles so that instead of being able to see a mass missile launch coming from light minutes away the damn things launch from inside CM range and give you almost no time to respond. Worse, the missiles carried on such pods could be a SD-level laser head with only a CM sized drive, since it doesn't need more range than that. Basically, imagine a pod full of Vipers that hit as hard as Mark 23s, that can launch from less than a million km out with no warning.

The Frankenstein'd spider-pod thing might take up as much space as two or three standard MDM pods - maybe even could only be carried externally or in a freighter - but it might be so devastating to be worthwhile.

tlb wrote:Yes, but that is a tweak; the newer Cataphracts used a larger, higher powered CM drive.

Isn't the relationship simple? A CM makes a trade off between acceleration and endurance for a fixed amount of power; the larger CM regains some endurance at increased acceleration by having larger plasma capacitors? However there must also be a limit set by engine life at each power rating, otherwise a single drive missile could have the same flight profile as a MDM without a programmed ballistic stage.

If the RMN manage the breakthrough to allow each drive to run at a different power setting, then that would be more impressive. That might also allow the final stage run at a higher acceleration than currently available.

The 2nd stage uses a CM derived drive. The first stage was (originally) the same drive and the SLN's currently deployed missiles. And even that original Cataphract's 1st stage had a higher acceleration than current RMN drive (other than CMs)

(borrowed/tweaked from a recent post of mine)
Depending on the Cataphract version the 1st stage burnout velocities seem to be:
Original (per Duckk's post):
180 seconds @ 467 KPS^2 (47,600g) = 0.2804c
Cataphract II (per SoV eArc):
180 seconds @ 561 KPS^2 (57,200g) = 0.3368c
Filaretta's (per UH):
180 seconds @ 710 KPS^2 (72,400g) = 0.4263c
Latest (per UH):
180 seconds @ 840 KPS^2 (85,700g) = 0.5043c

In contrast the first drive of a Mk23 is:
180 seconds @ 451 KPS^2 (46,000g) = 0.271 c



That means even the SLN missile derived stage was 3.5% better than the current RMN missile drives. (Though to be fair, if we go by the numbers from the books the Mk23s are a reversion to a lower performance drive. The final pre-fusion MDMs we saw had gotten up to 48,000 gees at that half-power, 3 minutes per drive, setting)

Then the MAlign made extraordinary improvements from there, coming close to doubling that performance without reducing drive endurance! And all that on a drive capable of lasting 3 minutes.


(I suppose they might have sacrificed flexibility and made that a fixed power setting - but unlike CMs it's not a 1 - 1.5 minute endurance; so that'd be a good trade-off. In the era of MDMs you're rarely firing them at full power, you strongly prefer the 3 minutes per drive setting. So if dropping support for the full power, 1 minute per drive, setting gave you 80% better acceleration that'd totally be worth it)

Jonathan_S wrote:The 2nd stage uses a CM derived drive. The first stage was (originally) the same drive and the SLN's currently deployed missiles. And even that original Cataphract's 1st stage had a higher acceleration than current RMN drive (other than CMs)

(borrowed/tweaked from a recent post of mine)
Depending on the Cataphract version the 1st stage burnout velocities seem to be:
Original (per Duckk's post):
180 seconds @ 467 KPS^2 (47,600g) = 0.2804c
Cataphract II (per SoV eArc):
180 seconds @ 561 KPS^2 (57,200g) = 0.3368c
Filaretta's (per UH):
180 seconds @ 710 KPS^2 (72,400g) = 0.4263c
Latest (per UH):
180 seconds @ 840 KPS^2 (85,700g) = 0.5043c

In contrast the first drive of a Mk23 is:
180 seconds @ 451 KPS^2 (46,000g) = 0.271 c



That means even the SLN missile derived stage was 3.5% better than the current RMN missile drives. (Though to be fair, if we go by the numbers from the books the Mk23s are a reversion to a lower performance drive. The final pre-fusion MDMs we saw had gotten up to 48,000 gees at that half-power, 3 minutes per drive, setting)

Then the MAlign made extraordinary improvements from there, coming close to doubling that performance without reducing drive endurance! And all that on a drive capable of lasting 3 minutes.


(I suppose they might have sacrificed flexibility and made that a fixed power setting - but unlike CMs it's not a 1 - 1.5 minute endurance; so that'd be a good trade-off. In the era of MDMs you're rarely firing them at full power, you strongly prefer the 3 minutes per drive setting. So if dropping support for the full power, 1 minute per drive, setting gave you 80% better acceleration that'd totally be worth it)

Since it uses a CM drive, it would be useful to compare to the numbers for the RMN's CM, from At All Costs, Chapter 19

The Mark 31 counter-missiles Honor's ships were firing represented significant improvements even over the Mark 30 counter-missiles her command had used as recently as the Battle of Sidemore, only months before. Their insanely powerful wedges were capable of sustaining accelerations of up to 130,000 gravities for as much as seventy-five seconds, which gave them a powered range from rest of almost 3.6 million kilometers.

I realize this is not your point, since you were writing about the base stage, not the CM drive stage; but it is useful to note that the RMN technology is capable of high acceleration. So the numbers you cite might be the result of a trade-off, rather than a failure of technology.

tlb wrote:Since it uses a CM drive, it would be useful to compare to the numbers for the RMN's CM, from At All Costs, Chapter 19

The Mark 31 counter-missiles Honor's ships were firing represented significant improvements even over the Mark 30 counter-missiles her command had used as recently as the Battle of Sidemore, only months before. Their insanely powerful wedges were capable of sustaining accelerations of up to 130,000 gravities for as much as seventy-five seconds, which gave them a powered range from rest of almost 3.6 million kilometers.

I realize this is not your point, since you were writing about the base stage, not the CM drive stage; but it is useful to note that the RMN technology is capable of high acceleration. So the numbers you cite might be the result of a trade-off, rather than a failure of technology.

Though you have to look at the CM drive performance on the Cataphract.
The first one had a decent but not amazing CM drive accel: 98,000 gees. But note that even then the MAlign had cracked the improved endurance, so it lasted 75 seconds instead of the 60 seconds that was universal for CMs until the RMN unveiled their most recent CMs after Sidemore.

RMN's Mk30 at Sidemore seems to have been 60s @ 120,000 gees.
RMN's Mk31 is 75s @ 130,000 gees
Prior to that RFC was a lot less precise about CM performance (one of the best references was way back in HotQ, and none too good. Different sides watching the same RMN CMs: "acceleration of over 900 KPS^2" and "at almost a thousand KPS^2". I'm figuring that's probably closer to 960 KPS^2 (98,000 gees) than 900 (91,800g) or 1,000 (102,000g)

It appears the SLN CM at Manticore was around a 60s @ 100,000 gees design (max range stated to be just under 1.8 million km)

But to get the range given for the latest cataphract the MAlign had to have a CM derived 2nd stage of at least 75s @ 100,000g and I think it most likely closer to 120,000g.
Issue is we're not given a accel for the 2nd stage; just "powered envelope of almost thirty-two million klicks" and with the first stage performance given a 2nd stage accel of
100,000g = 31,328,287 km
110,000g = 31,603,912 km
120,000g = 31,879,537 km
130,000g = 32,155,162 km
So the MAlign's CM drives aren't all that far behind Manticore's Mk31. And they're significantly better than what Manticore had deployed less than 2 years ago.

The Apollo FTL is a massive RMN advantage. But Manticore has little apparent lead in CM drives and seem far behind in normal missile drive tech (admittedly their MDMs make improving the performance of each drive significantly less important for them - so it probably hasn't been a research focus. And, as noted, their current MDMs are actually lower accel that some older ones. Quite possibly they gave up acceleration to shrink size as much as possible when the micro-fusion power source became available.)

This goes back to the questions that I had earlier:

Isn't the relationship simple? A CM makes a trade off between acceleration and endurance for a fixed amount of power; the larger CM regains some endurance at increased acceleration by having larger plasma capacitors? However there must also be a limit set by engine life at each power rating, otherwise a single drive missile could have the same flight profile as a MDM without a programmed ballistic stage.

Does anyone know?

Galactic Sapper wrote:Or some unholy combination of techs, such as grafting a spider drive to a pod full of missiles so that instead of being able to see a mass missile launch coming from light minutes away the damn things launch from inside CM range and give you almost no time to respond. Worse, the missiles carried on such pods could be a SD-level laser head with only a CM sized drive, since it doesn't need more range than that. Basically, imagine a pod full of Vipers that hit as hard as Mark 23s, that can launch from less than a million km out with no warning.

The Frankenstein'd spider-pod thing might take up as much space as two or three standard MDM pods - maybe even could only be carried externally or in a freighter - but it might be so devastating to be worthwhile.

What's frightening is that the MAlign may realize the same thing, hence, you may have given us a prelude to what wicked this way comes with the Lenny Dets. Batten down the hatches!

P.S. Sorry it took me three edits to get the ? right. I could have used Weird Harold's help you with the ?. I always wondered about the effect across the board if some piece of tech completely fell into enemy hands.

Someone upstream asked . . .

A Remontoire is the mechanism that sits between the mainspring and the escapement. It captures energy from the mainspring and releases it to the escapement -- in this case -- every 8 seconds. It smooths out the force from the winding mechanism delivered to the escapement. Which eliminates the problem of the movement running faster on a fully would spring then slowing. Works right down to the last minute. The beautiful clear display back is stunning.

tlb wrote:This goes back to the questions that I had earlier:

Isn't the relationship simple? A CM makes a trade off between acceleration and endurance for a fixed amount of power; the larger CM regains some endurance at increased acceleration by having larger plasma capacitors? However there must also be a limit set by engine life at each power rating, otherwise a single drive missile could have the same flight profile as a MDM without a programmed ballistic stage.

Does anyone know?

There is definitely a limit on engine life at each setting. All missiles have overpowered drive nodes, and they burn out - literally the ultra delicate molecular level structures within the nodes appear to break down and fail after a given time.

Normal single-drive missiles, regardless of onboard power, historically had a drives that burned out (not ran out of power) after 60 seconds at full acceleration or 180 seconds at half acceleration. So without figuring out how to build more robust, long lasting, nodes adding power doesn't improve endurance. That's why a Mk16 with a microfusion power source that could run the missile for far longer than the 6 minutes it's drive last can't match the powered endurance of the 3 drive Mk23 - all the power in the world doesn't help when the drives still burn out and fail after 3 minutes (at half power)

The books say missile drives can be set to other acceleration settings -- but in practice we've never seen that. (Logically implying that there's almost never any advantage to it). Now, as missile drive technology improves, the acceleration they can manage for those 60/180 seconds improves - but until quite recently the duration didn't.

Extended range missiles (ERMs) used some breakthrough or brute force to design a drive with at least 25% longer before the nodes burned out. That gave these missiles a run time of 75 seconds at full power or 225 seconds at half power. I had thought the Sag-B's carried one with even more endurance, but the Hypatia fight showed them firing for just 225s @ 45,500g (so they may have given up 1% of their accel to get nodes capable of 25% greater endurance)

CMs gave up that accel flexibility, exchanging a fixed acceleration (seemingly somewhere from 0-10% more than an equivalent missile's full power) for a wider wedge and a smaller missile body. So they had the same 60 seconds till node burnout as their bigger shipkiller cousins did at their full power; but lacked any half power setting and had tradeoffs allowing more CMs to be carried and each to be more effective at intercepting with their wedges.

The SLN CM's at Manticore were about 5% quicker than their shipkillers (100,000 gees vs 95,000 gees). But the RMN's Mk30 at Sidemore was quite a bit better than that, 30% quicker (120,000 gees vs 92,000 gees). And Haven's CM's at Sidemore, despite all Shannon could do, were apparently no better than their missiles "maximum intercept range of little more than one and a half million [km]" 92,000 gees would give 1.62 million; so I'd be hard pressed to grant them more accel/range than that)
All those were still at 60s to burnout. Then of course the RMN's Mk31/Viper rolled out with its vastly superior performance 75s @ 130,000 gees.

Brigade XO wrote:That spider drive makes the the graser torpedos relativly slow which actualy an advantage since it allows for better manuvering and time-on-target once you fire and swing the beam through your undefended target and damage the largest amout of area vs tying to pivot to do the same thing in a highspeed pass.

But only against targets whose position you can reliably predict in advance. Otherwise, they have far more acceleration and the torpedo can't follow the target.

ThinksMarkedly wrote:

Brigade XO wrote:That spider drive makes the the graser torpedos relativly slow which actualy an advantage since it allows for better manuvering and time-on-target once you fire and swing the beam through your undefended target and damage the largest amout of area vs tying to pivot to do the same thing in a highspeed pass.

But only against targets whose position you can reliably predict in advance. Otherwise, they have far more acceleration and the torpedo can't follow the target.

RMN ships spend somewhere over 80% of their operational lifetime without a running wedge & sidewall. The operational life and maintenance of all the engineering components is based on this.