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tlb wrote:

cthia wrote:Something I always meant to ask. I remembered it while watching the movie The Challenger Disaster.

MDMs have three stages. What happens to each stage as it burns out? Does it remain with the missile or separate like our current rockets. Does a burned out stage have any use? Seems like detaching the burnt stage would offer a smaller target to point defense, since the extra mass isn't going to be used to ram. It might even allow a bit more performance from the remaining missile.

That's how solid rocket boosters work anyways. Of course, I've never heard of them being detached. And I suppose geometry and the wedge might prevent that.

As I understand it, that is the way that the Cataphract works; but in the MDM the drive elements are stacked together with baffles in between. There is the single micro-fusion reactor that supplies power to each in turn, so nothing detaches.

We've never seen a diagram of the 3 Drive missiles, but David gave us a good look at the Mk 16 DDM at the back of SftS.

https://drive.google.com/file/d/1vTgKDlsdG8tWlIbHWKgKT28RRLWFKrnk/view?usp=sharing

The Nodes on the back (left side of the image) do not fall off, but continue with the missile after they burn out.

The shuttle boosters are not a great analogy, they are at their essence just a segmented pipe filled with burnable goo - but you thought that (like an MDM) they arn't staged in flight like a traditional rocket is correct, where as tlb said, the Catphract does come apart in stages.

tlb wrote:

cthia wrote:Something I always meant to ask. I remembered it while watching the movie The Challenger Disaster.

MDMs have three stages. What happens to each stage as it burns out? Does it remain with the missile or separate like our current rockets. Does a burned out stage have any use? Seems like detaching the burnt stage would offer a smaller target to point defense, since the extra mass isn't going to be used to ram. It might even allow a bit more performance from the remaining missile.

That's how solid rocket boosters work anyways. Of course, I've never heard of them being detached. And I suppose geometry and the wedge might prevent that.

As I understand it, that is the way that the Cataphract works; but in the MDM the drive elements are stacked together with baffles in between. There is the single micro-fusion reactor that supplies power to each in turn, so nothing detaches.

It's also my understanding DDMs and MDMs have 2 or 3 rings of drive elements all in a stack near the rear of the missile. Thanks TheEmile for the link to the diagram of the Mk16 DDM. (I think the drives of an MDM might be shown in the SD(P) illustration in the back of Ashes of Victory - but the ebook copy isn't high enough resolution to tell and I don't have my hardcover handy).

Those 2 or 3 impeller node rings each burn out after 60 or 180 seconds of operation (depending on power level) but nothing detaches. The "baffle" allows the inactive rings to survive being that close to the active impeller ring - but RFC has said in a post here that a limitation of the baffle technology (at least currently) is that it requires that all the rings use the same power setting. So no mixed power settings for DDMs / MDMs.

Whereas a Cataphract uses a booster stage based on a conventional anti-ship missile and "separate final stage carrying a standard laser head and a counter-missile’s drive system" [MoH]. This protects its 2nd drive by locating it physically far away from the 1st drive (and possibly something about this protection forces use of a smaller diameter than the booster stage). The books even talk about separation of that second stage.
The disadvantage of this design is that this make the Cataphract much longer than a DDM, and the 2nd stage's smaller size limits the warhead power compared to what a missile the diameter of the booster stage would normally carry. The advantage is that they can, and do, mix power settings - with the 2nd stage's CM drive providing a fixed "sprint mode" acceleration for it's portion of the powered flight.



This different why I try be consistent about referring to Cataphracts a two-stage missiles while calling DDMs and MDMs two-drive or three-drive missiles instead (because they don't actually stage).

tlb wrote:

cthia wrote:Something I always meant to ask. I remembered it while watching the movie The Challenger Disaster.

MDMs have three stages. What happens to each stage as it burns out? Does it remain with the missile or separate like our current rockets. Does a burned out stage have any use? Seems like detaching the burnt stage would offer a smaller target to point defense, since the extra mass isn't going to be used to ram. It might even allow a bit more performance from the remaining missile.

That's how solid rocket boosters work anyways. Of course, I've never heard of them being detached. And I suppose geometry and the wedge might prevent that.

As I understand it, that is the way that the Cataphract works; but in the MDM the drive elements are stacked together with baffles in between. There is the single micro-fusion reactor that supplies power to each in turn, so nothing detaches.

Jonathan_S wrote:It's also my understanding DDMs and MDMs have 2 or 3 rings of drive elements all in a stack near the rear of the missile. Thanks TheEmile for the link to the diagram of the Mk16 DDM. (I think the drives of an MDM might be shown in the SD(P) illustration in the back of Ashes of Victory - but the ebook copy isn't high enough resolution to tell and I don't have my hardcover handy).

Those 2 or 3 impeller node rings each burn out after 60 or 180 seconds of operation (depending on power level) but nothing detaches. The "baffle" allows the inactive rings to survive being that close to the active impeller ring - but RFC has said in a post here that a limitation of the baffle technology (at least currently) is that it requires that all the rings use the same power setting. So no mixed power settings for DDMs / MDMs.

Whereas a Cataphract uses a booster stage based on a conventional anti-ship missile and "separate final stage carrying a standard laser head and a counter-missile’s drive system" [MoH]. This protects its 2nd drive by locating it physically far away from the 1st drive (and possibly something about this protection forces use of a smaller diameter than the booster stage). The books even talk about separation of that second stage.
The disadvantage of this design is that this make the Cataphract much longer than a DDM, and the 2nd stage's smaller size limits the warhead power compared to what a missile the diameter of the booster stage would normally carry. The advantage is that they can, and do, mix power settings - with the 2nd stage's CM drive providing a fixed "sprint mode" acceleration for it's portion of the powered flight.

This different why I try be consistent about referring to Cataphracts a two-stage missiles while calling DDMs and MDMs two-drive or three-drive missiles instead (because they don't actually stage).

Thanks guys, and to TheEmile for the pics. Part of me wants to know the order in which they burn out but it still wouldn't help me. I am equating baffle with the Challenger's O-ring, inasmuch as it is a barrier channeling and protecting the missile's rings from heat.

I know the Cataphracts are larger to begin with, but should be a smaller than GA target during attack runs. Thanks again guys.

Jonathan_S wrote:It's also my understanding DDMs and MDMs have 2 or 3 rings of drive elements all in a stack near the rear of the missile. Thanks TheEmile for the link to the diagram of the Mk16 DDM. (I think the drives of an MDM might be shown in the SD(P) illustration in the back of Ashes of Victory - but the ebook copy isn't high enough resolution to tell and I don't have my hardcover handy).

Those 2 or 3 impeller node rings each burn out after 60 or 180 seconds of operation (depending on power level) but nothing detaches. The "baffle" allows the inactive rings to survive being that close to the active impeller ring - but RFC has said in a post here that a limitation of the baffle technology (at least currently) is that it requires that all the rings use the same power setting. So no mixed power settings for DDMs / MDMs.

Whereas a Cataphract uses a booster stage based on a conventional anti-ship missile and "separate final stage carrying a standard laser head and a counter-missile’s drive system" [MoH]. This protects its 2nd drive by locating it physically far away from the 1st drive (and possibly something about this protection forces use of a smaller diameter than the booster stage). The books even talk about separation of that second stage.
The disadvantage of this design is that this make the Cataphract much longer than a DDM, and the 2nd stage's smaller size limits the warhead power compared to what a missile the diameter of the booster stage would normally carry. The advantage is that they can, and do, mix power settings - with the 2nd stage's CM drive providing a fixed "sprint mode" acceleration for it's portion of the powered flight.



This different why I try be consistent about referring to Cataphracts a two-stage missiles while calling DDMs and MDMs two-drive or three-drive missiles instead (because they don't actually stage).

if you note in the picture, the node's alignment in the 2 rings are 22.5 degrees off from each other. I don't know if that is artistic license, or if the nodes are aligned that way to assist their protection from one another.

Also I believe Maxx Q has some missile renders on his site that might be helpful.

yep - https://www.deviantart.com/maxxqbunine/art/Family-Portrait-002-465723413

the nodes are offset in the 3 drive missiles as well, the mis-alignment has to be to protect the nodes.

Jonathan_S wrote:The disadvantage of this design is that this make the Cataphract much longer than a DDM, and the 2nd stage's smaller size limits the warhead power compared to what a missile the diameter of the booster stage would normally carry. The advantage is that they can, and do, mix power settings - with the 2nd stage's CM drive providing a fixed "sprint mode" acceleration for it's portion of the powered flight.

The Oyster Bay version did have the CM drive last, but a full size warhead. From Mission of Honor, chapter 29:

the pod-launched missiles of Oyster Bay were Cataphract-Cs, based on the capital-ship Trebucht, with much heavier and more powerful laserheads

Even it a DD missle has the 1st stage which is detached at the ignition of the 2nd stage that now essentilaly inert 1st stage isn't going to have any impact on the engagement- unless the opposing forces are charging down each other's throates on reciprocal courses. Why? Because the 1st stage AT MOST retains the momentum and velocity of when it was dropped and isn't going to add anymore- it's no longer under power.
So if your shooting at any kind of intercept angle against ships which are accelerating (especialy if they are changing vectors at the same time) the 1st stages are POSSIBLY going to cross their course track but well behind the ships. I don't recall any mention to what happens to the dropped 1st stage when the 2nd stage lights off it's impellers. Like does that impeller effect do anything to something that is directly "behind" the 2nd stage. Remember, these are not chemical rockets and there is no ionized or gasious material being ejected sternward for thrust.

Also don't remember if the 1st stage would be just dropped after burnout or would it be retained so as not to change the dynamics of the rest of the missile in the bellistic phase. Yes, I know, there isn't any atmosphere to affect the ballistics but there is gravity and unless perfectly ballanced release you might set the second stage tumbling.

Even if the 1st stage were dripped just before the missil entered terminal phase, it wouldn't show up on the sensors as something under drive- unless you put something on it that MIGHT distract the defence algorithms into thinking these were ballistic warheads and force them to allocate CM's or engergy defences at them.

Just saying.

Brigade XO wrote:Even it a DD missle has the 1st stage which is detached at the ignition of the 2nd stage that now essentilaly inert 1st stage isn't going to have any impact on the engagement- unless the opposing forces are charging down each other's throates on reciprocal courses. Why? Because the 1st stage AT MOST retains the momentum and velocity of when it was dropped and isn't going to add anymore- it's no longer under power.
So if your shooting at any kind of intercept angle against ships which are accelerating (especialy if they are changing vectors at the same time) the 1st stages are POSSIBLY going to cross their course track but well behind the ships. I don't recall any mention to what happens to the dropped 1st stage when the 2nd stage lights off it's impellers. Like does that impeller effect do anything to something that is directly "behind" the 2nd stage. Remember, these are not chemical rockets and there is no ionized or gasious material being ejected sternward for thrust.

Also don't remember if the 1st stage would be just dropped after burnout or would it be retained so as not to change the dynamics of the rest of the missile in the bellistic phase. Yes, I know, there isn't any atmosphere to affect the ballistics but there is gravity and unless perfectly ballanced release you might set the second stage tumbling.

Even if the 1st stage were dripped just before the missil entered terminal phase, it wouldn't show up on the sensors as something under drive- unless you put something on it that MIGHT distract the defence algorithms into thinking these were ballistic warheads and force them to allocate CM's or engergy defences at them.

Just saying.

It does make you wonder what happens to the separated stages. That adds to the debris in a system for one. It also seems like a lousy design as far as security if the enemy can acquire one of those stages and learn something from it.

I'm also curious as to the size of the final missile on its attack run vs RMN missiles.

cthia wrote:It does make you wonder what happens to the separated stages. That adds to the debris in a system for one. It also seems like a lousy design as far as security if the enemy can acquire one of those stages and learn something from it.

I'm also curious as to the size of the final missile on its attack run vs RMN missiles.

However the GA would not learn anything new from an examination of what is basically a Solarian missile. The dropped first stage will be going fast enough to destroy itself on impact with anything in system (hopefully nothing inhabited, although the Malign does not really care) or else leave the system entirely.

I have no idea of the effect of the final stage size.

tlb wrote:

Jonathan_S wrote:The disadvantage of this design is that this make the Cataphract much longer than a DDM, and the 2nd stage's smaller size limits the warhead power compared to what a missile the diameter of the booster stage would normally carry. The advantage is that they can, and do, mix power settings - with the 2nd stage's CM drive providing a fixed "sprint mode" acceleration for it's portion of the powered flight.

The Oyster Bay version did have the CM drive last, but a full size warhead. From Mission of Honor, chapter 29:

the pod-launched missiles of Oyster Bay were Cataphract-Cs, based on the capital-ship Trebucht, with much heavier and more powerful laserheads

Hmm - I seem to have conflated things. The Cs are too large to fire from even capital ship tubes; but it seems that those pod launched missiles do carry capital grade warheads; meaning the 2nd stage is wide enough to fit that warhead bus.

I think I got myself confused by remembering that the SD's were firing Cataphracts with only BC grade warheads. But now that you've reminded my I realize that's because those are Cataphract-Bs built around the BC sized missile as the booster stage.

Thanks for straightening me out.

Brigade XO wrote:Also don't remember if the 1st stage would be just dropped after burnout or would it be retained so as not to change the dynamics of the rest of the missile in the bellistic phase. Yes, I know, there isn't any atmosphere to affect the ballistics but there is gravity and unless perfectly ballanced release you might set the second stage tumbling.

Even if the 1st stage were dripped just before the missil entered terminal phase, it wouldn't show up on the sensors as something under drive- unless you put something on it that MIGHT distract the defence algorithms into thinking these were ballistic warheads and force them to allocate CM's or engergy defences at them.

Just saying.

The text seems to imply that Cataphracts perform stage separation just before the 2nd stage's drive is ready to activate.

Shadow of Victory wrote:And if Pyun’s report was accurate, the Manties had launched their “demonstration salvo” at thirty million kilometers. That was damned near twice the range even the Flight Two Cataphract could manage in a continuous burn, but the Cataphract was a two-stage weapon. They could delay separation of the second stage for as long as they liked, then send it into the attack at twice the accel reported out of the Manties...

(emphasis added) That means you don't risk tumbling the missile during the ballistic coast, but that the 1st stage isn't around to possibly distract the defenses. OTOH I don't know that a CM-derived missile drive would work well if it has a massive booster stage sticking out well past the normal end of the missile - there's probably good reason the Cataphracts actually perform stage separation before lighting off that 2nd stage drive.