1926 PD - Export hardware

Relax wrote:Not that this matters as the portion I was discussing was MDM Pods for system defense(we aren't talking SDP here). Cataphracts out of pods can be ANY size one wishes. Current cataphracts were ONLY limited due to Garbage SLN designed ships using SDM's. By DW logic, they were morons and should have just used several CM drives attached to a NORMAL Capital grade Laser head.

I'll note that the towed pod Cataphract (which did have capital grade laser heads) were still only 2 stages. (so less flexible than the 3 drives of an MDM).

We don't know why the MAlign has seemingly not been willing or able to make any 3-stage Cataphracts for their pod-based variants. (And you'd need that third stage for CM drives to give higher terminal velocity than the current 2-stage SDM + CM design --- though it'd still be slower than an 3-stage SDM + SDM + CM design)



The other odd thing about Cataphracts is that the performance out of the 2nd stage CM drive is slightly anemic -- Ducck said the tech bible for the original Cataphracts has the 2nd stage pulling only 961 KPS^2 (about 98,060 gees) which is slow for a CM - though it does have the extended 75 second runtime which is nice; and in fact that only about 2% faster than the full power setting for its Javelin base stage (467 KPS^2 at 50%; meaning 934 KPS^2 at full).

And then later revisions of the Cataphract report significantly higher first stage acceleration while we get statements about the 2nd stage still being the same performance -- which would mean it is now slower than the SDM drive they're using on the first stage; at least if you turned the first stage up to full power. (Making it seem odd that they stuck with SDM + CM instead of SDM 50% + SDM 100%; though I guess the SDM at 100% would only have 60s endurance vs their CM drive's 75s)

Jonathan_S wrote:I'll note that the towed pod Cataphract (which did have capital grade laser heads) were still only 2 stages. (so less flexible than the 3 drives of an MDM).

You will note, these are export version out of the MALIGN. Why would they give their best to the SLN?

Jonathan_S wrote:We don't know why the MAlign has seemingly not been willing or able to make any 3-stage Cataphracts for their pod-based variants. (And you'd need that third stage for CM drives to give higher terminal velocity than the current 2-stage SDM + CM design --- though it'd still be slower than an 3-stage SDM + SDM + CM design)

The MALIGN were not ready to start building Fighting hardware. Tech advancement takes time and they had to cut corners. Had to make the Cataphract for SLN to try dulling the advantages of the GA.

Since apparently Cataphracts do not need a compensator field in which the mass resides determined by impeller physics ultimately determining the SIZE of an object, no reason cannot strap more CM drives to something as apparently baffles are near useless and no reason to have them. May as well make everything CM drives saving engineering + manufacturing time.

Jonathan_S wrote:The other odd thing about Cataphracts is that the performance out of the 2nd stage CM drive is slightly anemic -- Ducck said the tech bible for the original Cataphracts has the 2nd stage pulling only 961 KPS^2 (about 98,060 gees) which is slow for a CM - though it does have the extended 75 second runtime which is nice; and in fact that only about 2% faster than the full power setting for its Javelin base stage (467 KPS^2 at 50%; meaning 934 KPS^2 at full).

Uh, no, CM drive of 961KPS^2 is NOT anemic, that is standard CM drive accel as proscribed by early books unless you wish to state RMN CM's are worse than SLN CM's... That is standard for RHN CM's as well.

Jonathan_S wrote:And then later revisions of the Cataphract report significantly higher first stage acceleration while we get statements about the 2nd stage still being the same performance -- which would mean it is now slower than the SDM drive they're using on the first stage; at least if you turned the first stage up to full power. (Making it seem odd that they stuck with SDM + CM instead of SDM 50% + SDM 100%; though I guess the SDM at 100% would only have 60s endurance vs their CM drive's 75s)

I read that aspect as the SDM drive was revised as its runtime is longer and higher accel which made me when I first read it as it breaks pretty much the Universe logic of tech progression. And that is the next thing, CM drives can move a capital grade warhead JUST FINE by cataphract logic... and has endurance of 75s... Yet we are to believe an SDM cannot... --> Make this make sense?

Frankly the last couple books just wadded up all "tech progression balance" in the HV and threw it out the window so he could have the bad guys scratch the paint of the GA. ETERNAL DRIVE 20,000G RD's... Why bother with missiles?
I mean common man! Hello Power Physics? And that was the end of the series. Frankly I was HIGLY disappointed. He spent years carefully logically crafting his in universe physics and then wads it all up and throws it away.

Relax wrote:Since apparently Cataphracts do not need a compensator field in which the mass resides determined by impeller physics ultimately determining the SIZE of an object, no reason cannot strap more CM drives to something as apparently baffles are near useless and no reason to have them. May as well make everything CM drives saving engineering + manufacturing time.

I cannot find the quote right now, but it is my understanding that no missile has a separate compensator. Instead there is something which serves the same purpose built into the wedge generator. I do not know what limitations that imposes.

Relax wrote:

Jonathan_S wrote:I'll note that the towed pod Cataphract (which did have capital grade laser heads) were still only 2 stages. (so less flexible than the 3 drives of an MDM).

You will note, these are export version out of the MALIGN. Why would they give their best to the SLN?

But we also didn't see any 3-stage version at Galton or during Oyster Bay. Times when the MAlign was using their own Cataphracts in anger -- and both of those situations were pod-launched Cataphracts; so no need to overly worry about size.

Relax wrote:

Jonathan_S wrote:The other odd thing about Cataphracts is that the performance out of the 2nd stage CM drive is slightly anemic -- Ducck said the tech bible for the original Cataphracts has the 2nd stage pulling only 961 KPS^2 (about 98,060 gees) which is slow for a CM - though it does have the extended 75 second runtime which is nice; and in fact that only about 2% faster than the full power setting for its Javelin base stage (467 KPS^2 at 50%; meaning 934 KPS^2 at full).

Uh, no, CM drive of 961KPS^2 is NOT anemic, that is standard CM drive accel as proscribed by early books unless you wish to state RMN CM's are worse than SLN CM's... That is standard for RHN CM's as well.

Yes, that's pretty normal for 20 year old CMs (the early books) - but the RMN CMs are now up to 130,000g (1,274 KPS^2) - making 961KPS^2 seem a little behind the times.

And SLN CMs might be a bit faster than the 20 years old RMN CMs. I was never able to find hard numbers on the old CMs. OBS simply says the CMs of the CL Fearless were "over ninety thousand gravities" (so, over 833 KPS^2), and HotQ says the CA Fearless fired CMs "at more than nine hundred" KPS^2 (so over 92,000g). But the Javelin was a bit quicker than RMN SDMs (95,300g vs 85,000g), so it wouldn't be too surprising if the SLN CM was a bit quicker too, compared to old RMN CMs. But either way, good for 20 years ago is still a little anemic for today.

Also, if you look at CMs vs their contemporary SDMs it also seems a touch sluggish. RMN CMs seems to be at least 6% quicker than the full power setting of their counterpart SDMs; while the Cataphract has merely about a 2% accel advantage for its CM drive over its SDM drive.

So on both relative and absolute terms I remain a little surprised that the CM drive of the Cataphract isn't a bit quicker.

tlb wrote:I cannot find the quote right now, but it is my understanding that no missile has a separate compensator. Instead there is something which serves the same purpose built into the wedge generator. I do not know what limitations that imposes.

I'm not finding it either (and I tried text searched, checking my doc of RFC posts, and the archived old infodump site) - but I also remember it stated somewhere that missiles didn't have standalone compensators list ships did but instead the missile drive itself somehow provided (partial?) compensation effect. (I did find a 13-Jun-2014 post in "LAC not so useful after all?" mentioning modern missiles had "a better compensator effect" than those of 400-500 years earlier; but that's not the smoking gun text-ev I recall)

Jonathan_S wrote:But we also didn't see any 3-stage version at Galton or during Oyster Bay. Times when the MAlign was using their own Cataphracts in anger -- and both of those situations were pod-launched Cataphracts; so no need to overly worry about size.

During Oyster Bay, the MAlign was likely not ready with their true MDMs. For Galton, we know the Darius TPTB withheld the Ninurta missile. Whether that is a true MDM or just another iteration over the Cataphract, we don't know. Maybe they did put three stages on top of each other...

The problem with 3 missiles nose-to-tail is that it's mighty long. You can't fire it from a missile tube aboard a ship whose radius is less than the missile's length. That was the big problem with the Cataphracts: each ship type carried the lesser ship type's missile and warhead due to size constraints. The capital ship grade Cataphract-C could only be fired from pods.

I'm not finding it either (and I tried text searched, checking my doc of RFC posts, and the archived old infodump site) - but I also remember it stated somewhere that missiles didn't have standalone compensators list ships did but instead the missile drive itself somehow provided (partial?) compensation effect. (I did find a 13-Jun-2014 post in "LAC not so useful after all?" mentioning modern missiles had "a better compensator effect" than those of 400-500 years earlier; but that's not the smoking gun text-ev I recall)

Also the fact that you don't have people inside that need to be kept under 2 gravities of acceleration. I can't think of any material that can sustain 100,000 gravities of constant acceleration, but if this field reduces to a "mere" 100 gravities or even 1000, material science can deal with the rest.

I believe DW discussed a missiles' compensator in appendix of either More than Honor or SVW. Might be in OBS. One of those very early books is all I remember. A lot of base Honorverse Physics are detailed in those first ~4 books.

Compensator for a missile is built directly into the impeller nodes themselves. This only allows 1 or 2 settings unlike stand alone compensators used on ships.

ThinksMarkedly wrote: I can't think of any material that can sustain 100,000 gravities of constant acceleration,

Actually materials survive 100k G just fine. What they do NOT survive is the dervivative of acceleration--> Jerk. This is what shatters materials. The rate of acceleration change.

Think of it this way an constant acceleration, just means the object in question WEIGHs more with a slight increase in compressive stresses mostly. Now if you take that same exaggerated weight and start JERKing it back and forth, this creates MASSIVE tensile stresses which shears things quite quickly.

Lets put it this way. A sharp explosion in a gun barrel is ~50,000G. A softer explosion is ~10,000G. A VERY sharp explosion is 100,000G. Very crude approximations, but you get the gist. In WWII were we firing timed proximity fuses out of gun barrels? --> Yes. Today, are we firing guidance electronics out of gun barrels? Yes. No, it is not 100k G being shot out. Nor is it 50,000G either. The problem is the RATE at which the acceleration is applied.

So, in Honorverse, how quickly is the acceleration first applied? What is the variance in acceleration over its duration? How fast(jerk) does the acceleration stop? Could missiles move without compensators at 100kG? Possible. is that weight of extra structural mass greater than adding a compensator to impellers? Apparently the structural mass is greater than adding a compensator in the honorverse to missiles. Or for all we know, the Gravitic sensors on a missile CANNOT function at 100K G. A distinct possibility.

Relax wrote:Actually materials survive 100k G just fine. What they do NOT survive is the dervivative of acceleration--> Jerk. This is what shatters materials. The rate of acceleration change.

I don't doubt that the jerk or the snap or the other further derivatives can be a problem.

But not all materials will survive large accelerations, especially not delicate ones.

Think of it this way an constant acceleration, just means the object in question WEIGHs more with a slight increase in compressive stresses mostly. Now if you take that same exaggerated weight and start JERKing it back and forth, this creates MASSIVE tensile stresses which shears things quite quickly.

Indeed, it's being compressed, constantly. That is a stress in itself and can cause material failure.

I agree that compression stress is easier to tolerate than tensile or rotational stresses. I'll also agree that failures are likely to happen within the first second or so, and if they don't, they aren't likely at all. But that does not mean none.

Lets put it this way. A sharp explosion in a gun barrel is ~50,000G. A softer explosion is ~10,000G. A VERY sharp explosion is 100,000G. Very crude approximations, but you get the gist. In WWII were we firing timed proximity fuses out of gun barrels? --> Yes. Today, are we firing guidance electronics out of gun barrels? Yes. No, it is not 100k G being shot out. Nor is it 50,000G either. The problem is the RATE at which the acceleration is applied.

It's sustaining that much acceleration for a very short period of time, not for hundreds of seconds. I don't know that we've ever put any material under thousands of gravities of acceleration for multiple seconds. 10 seconds times 50,000 G is at nearly 5000 km/s after all and the object is over two thirds of the way to geosynchronous orbit at 24500 km away.

Or for all we know, the Gravitic sensors on a missile CANNOT function at 100K G. A distinct possibility.

They seem to be very myopic, but still work just fine. They can see the wedges of the ships they're targetting in sprint mode at 92,000G and CMs can see the wedges of the missiles they're countering at 130,000 G.

ThinksMarkedly wrote:
Other derivatives: SNIP

But not all materials will survive large accelerations, especially not delicate ones.

ThinksMarkedly wrote:Indeed, it's being compressed, constantly. That is a stress in itself and can cause material failure.

It's sustaining that much acceleration for a very short period of time, not for hundreds of seconds. I don't know that we've ever put any material under thousands of gravities of acceleration

[/quote]
1) There are no other derivatives, It is linear. Not how strength of materials/physics work Derivative of distance is velocity. Derivative of velocity is acceleration. Derivative of acceleration is Jerk. There is no further derivative.

2) Yes, we have put materials under THOUSANDS of G's acceleration for Hours/Days/Weeks. Heard of a thing called a CENTRIFUGE?

How the Heck did you think we engineered materials, simple circuits, etc which can be FIRED OUT OF A GUN BARREL using glass ampules etc in WWII???? Let alone guided munitions using circuit boards and delicate accelerometers in the 1990's???

<<Palm in face>>

3) Constant stress ANY material can sustain ~by and large. CREEP of a material is effected by stress, temperature, and cyclic rate. [grain orientation as well, but that is more advanced but same principles] So, if something can sustain the initial JERK to get to a constant acceleration, it will be just fine for ~180s. I suppose in an 3 stage MDM, it has to sustain the Jerk from 0-->x G's 6 times. This is your main cyclic rate. The Minor cyclic rate is determined by how constant that acceleration is. If 100,000G is the Mean, what is the oscillation amplitude and Frequency around that 100,000G. Could easily be off +/-5%.

Now a mean load of 100,000G may indeed be just fine for a material, but if the material is also undergoing an oscillation of 5000G on a cyclic rate of 1 Hz, or 1000Hz--> AKA its JERK derivative, then we could have some serious problems. THe faster the frequency the greater the Jerk. --> This is why your statement of sustained ~100,000G could indeed be why Impeller missiles in HV have compensators built in. Or, LASER rods cannot sustain the 100,000G. Or say the Grav lens tech cannot do so, or micro fusion bottle, or fusion capacitors.... etc etc etc.

Relax wrote:1) There are no other derivatives, It is linear. Not how strength of materials/physics work Derivative of distance is velocity. Derivative of velocity is acceleration. Derivative of acceleration is Jerk. There is no further derivative.

The derivative of the jerk is the snap.

Whether that has any effect on materials, I don't know. According to Wikipedia, minimising the snap is important for curves, as a constant snap means the change in jerk is linear, allowing for a smooth radial acceleration.

2) Yes, we have put materials under THOUSANDS of G's acceleration for Hours/Days/Weeks. Heard of a thing called a CENTRIFUGE?

Yes, indeed. I did not think of radial acceleration, but it of course matters.

How the Heck did you think we engineered materials, simple circuits, etc which can be FIRED OUT OF A GUN BARREL using glass ampules etc in WWII???? Let alone guided munitions using circuit boards and delicate accelerometers in the 1990's???

I thought there was a way, but I couldn't come up with an answer of what it was. And, like I said, those don't need to sustain the acceleration for long, as they're going to go ballistic or terminal velocity very quickly, so the method by which the sudden acceleration was tested need not have been capable of sustaining it for longer than a few seconds.

3) Constant stress ANY material can sustain ~by and large. CREEP of a material is effected by stress, temperature, and cyclic rate. [grain orientation as well, but that is more advanced but same principles] So, if something can sustain the initial JERK to get to a constant acceleration, it will be just fine for ~180s.

I'll have to trust you on that. I have no reason to doubt it is true; if the material isn't deforming in the first few seconds, why should it deform afterwards? But if it is deforming, even minutely, then the sustained acceleration could deform it past the breaking point.

I suppose in an 3 stage MDM, it has to sustain the Jerk from 0-->x G's 6 times. This is your main cyclic rate. The Minor cyclic rate is determined by how constant that acceleration is. If 100,000G is the Mean, what is the oscillation amplitude and Frequency around that 100,000G. Could easily be off +/-5%.

It doesn't look like there's a cycle rate at all. Once the wedge is up to full acceleration, it stays there. We could assume it oscillates a little as imperfections in the power production methodology and so missiles can adjust to each other's power output, but that also goes against the "one setting or bust" explanations we've heard.

MDMs are only expected to shut down once, before the last stage, so they would expect only 4 changes in acceleration at most, however many stages the missile has. There's no need to shut down the wedge at any time before that, because it does not extend your range but does extend your time to target. The only reason to shut down between the first and second stages is to use the third stage as a surprise, but that means your enemy must not know you have a 3-stage-capable missile, or at least one that can be fired from the current circumstances (say, a DD or CL).

Finally, the GA-tech missiles have been pretty constantly using 46,000 gravities for a 180-second half-power stage and 92,000 for 60-second full power. Only CMs appear to break over the 100,000-gravity threshold.

Now a mean load of 100,000G may indeed be just fine for a material, but if the material is also undergoing an oscillation of 5000G on a cyclic rate of 1 Hz, or 1000Hz--> AKA its JERK derivative, then we could have some serious problems. THe faster the frequency the greater the Jerk. --> This is why your statement of sustained ~100,000G could indeed be why Impeller missiles in HV have compensators built in. Or, LASER rods cannot sustain the 100,000G. Or say the Grav lens tech cannot do so, or micro fusion bottle, or fusion capacitors.... etc etc etc.

Good points.

RFC could use some of this for some plot device for why no one can currently go above 150,000 gravities even for a CM, as the oscillations however minor become too great for the wedge's compensating field at that point. And if someone does make a breakthrough in that problem, penny's dream of the million-gravity missile could come true.

I should also point out that if the acceleration is oscillating up and down, that mean the jerk is not constant, which in turn must mean snap is not zero either (I'm not going to assume they're pure sine waves).