Sprint drive

cthia wrote:

I always thought it was a waste, for end of run missiles to complete their runs, with copious amounts of drive time left on tap. Can we utilize all of the remaining drive time in an all out burst?

I'm not sure it can be done. But I'm certainly sure of its proposed effectiveness, if used correctly.

I would imagine it could be programmed in, but I can't see why. If you don't have 'spare' drive time available, the Tactical Officer/Captain can't make tactical decisions about launch distance, time of flight etc. They also don't have enough time on the clock for last second evasive manoeuvres either, or course changes for tactical reasons.

Extra drive time is no more 'wasted' than extra fuel is 'wasted' at the end of a flight. Sometimes you'll need all the drive time, sometimes you won't. But when you do need it, you'll really need it.

Bluesqueak wrote:

cthia wrote:

I always thought it was a waste, for end of run missiles to complete their runs, with copious amounts of drive time left on tap. Can we utilize all of the remaining drive time in an all out burst?

I'm not sure it can be done. But I'm certainly sure of its proposed effectiveness, if used correctly.

I would imagine it could be programmed in, but I can't see why. If you don't have 'spare' drive time available, the Tactical Officer/Captain can't make tactical decisions about launch distance, time of flight etc. They also don't have enough time on the clock for last second evasive manoeuvres either, or course changes for tactical reasons.

Extra drive time is no more 'wasted' than extra fuel is 'wasted' at the end of a flight. Sometimes you'll need all the drive time, sometimes you won't. But when you do need it, you'll really need it.

I certainly agree with you for the most part, Bluesqueak, however, I think you and I disagree on what is actually considered "copious" amounts of drive time left.

I'm specifically recalling the demonstration launch during SoV when the missile continued on, paraphrasing "...one minute...two minutes...three minutes...four minutes?," beyond targeted SLN ships, recognized by the frightened SLN CO.

I forgot the encounter. No time to look it up. Three or four minutes inside your missile envelop should cause the RMN AI to select available sprint mode. Certainly the AI can calculate :CONDITIONS :SPRINT MODE.

Maldorian wrote:Maybe I wrote my post not clear enough or you are misunderstanding me:

"I am NOT talking about the Cataphracts! I am talking about the Sprint Drive technology and if it is useful for manty missles."

If you're talking about the "Sprint Drive" the MAlign puts on its dispatch boats and other starships, that is useless on missiles because that is a Hyper-generator rather than an improved impeller drive. It is called "Sprint" because it allows a ship to reach higher hyper bands -- with consequent decrease in travel time in hyperspace.

If you're talking about a "Sprint Drive" on a missile, Cataphracts are the only missiles currently employed by any combatant that has a CM-derived second stage drive. If you're talking about the missiles provided the PNE for the attack on Torch, you're talking about Cataphracts.

The System Defense variant of Apollo aside, Manticoran missiles already have more advantages than pure speed in the final stage and speed alone can be compensated for with software upgrades.

What would be far more useful, IMHO, would be a final drive with "infinitely variable speed" so the defensive systems don't have a simple "binary" choice of speeds for aiming prediction. If defenses actually have to measure the speed of incoming missiles, rather than simply identifying the missile type and selecting from "fast" or "slow" it would delay response fractionally and complicate computation of lead-angle.

cthia wrote:I certainly agree with you for the most part, Bluesqueak, however, I think you and I disagree on what is actually considered "copious" amounts of drive time left.

I'm specifically recalling the demonstration launch during SoV when the missile continued on, paraphrasing "...one minute...two minutes...three minutes...four minutes?," beyond targeted SLN ships, recognized by the frightened SLN CO.

I forgot the encounter. No time to look it up. Three or four minutes inside your missile envelop should cause the RMN AI to select available sprint mode. Certainly the AI can calculate :CONDITIONS :SPRINT MODE.

Ah, that one. I did have time to look it up - Chapter 67, I think. But you're misremembering it; the countdown is the horrified Solly crew realising the Manty missile has just gone one minute ... two minutes ... three minutes beyond the powered flight time of their own missiles. It's still heading towards them, though. And, in fact is still under powered flight (and so can dodge their anti missile defences) right up to the point where it goes past them and explodes at a safe distance from their ships.

That final distance as it goes past, blowing raspberries, is something like 85 seconds, not the eight minute countdown.

cthia wrote:I certainly agree with you for the most part, Bluesqueak, however, I think you and I disagree on what is actually considered "copious" amounts of drive time left.

I'm specifically recalling the demonstration launch during SoV when the missile continued on, paraphrasing "...one minute...two minutes...three minutes...four minutes?," beyond targeted SLN ships, recognized by the frightened SLN CO.

I forgot the encounter. No time to look it up. Three or four minutes inside your missile envelop should cause the RMN AI to select available sprint mode. Certainly the AI can calculate :CONDITIONS :SPRINT MODE.

You mean this encounter, where all nine minutes of powered missile flight were used to chase down the SLN ship?

Shadow of Victory, Chapter 67 wrote:“I am Captain Aldus O’Brien, Royal Manticoran Navy, commanding Her Majesty’s Ship Trebuchet,” he said coldly. “I’m also the senior officer of Task Group Ten-Two-Eight, and my orders are to take or destroy any Solarian naval units in this star system. Be advised that you are now in range of my missiles.”
Despite himself, Ibañez felt his face tighten. It had almost certainly turned pale, as well, he thought. If O’Brien was telling the truth, his missiles had a range of over thirty-six million kilometers! It was true the Manties had built their overtake velocity advantage to over 30,000 KPS, which would boost their effective range significantly, but even so—!
“I realize you may doubt whether or not you are, indeed, in my range envelope. Accordingly—”
“Missile launch!” Lieutenant Commander Stedman said suddenly. “One missile closing at an overtake of one-three-six KPS squared!”
Ibañez watched the display as the single missile icon streaked after his ship. It accelerated fiercely, but it also had thirty-six million kilometers to go. The impellers on a Javelin, the SLN’s latest missile, would burn out three minutes after launch, which would have given an effective envelope of just under eight million kilometers from that geometry. It could still have caught Harpist, assuming no radical course changes on her part, but its overtake velocity when it did would have been down to a mere 5,000 KPS and it would have long since gone ballistic. That would have made it dead meat for point defense, nor would it have been able to execute any terminal attack maneuver to bring its laserhead to bear, which would have made the chance of actually hitting the ship nonexistent. But this wasn’t a Solarian missile, and his stomach turned into a hollow, singing void as it went on accelerating at 46,000 KPS2.
The Javelin’s acceleration was actually seven percent higher than that…but this missile accelerated effortlessly past the hundred eighty second-mark where a Javelin’s drive would have failed. Four minutes. Five minutes. Six minutes. Seven minutes.
He felt his jaw clamping harder and harder in something very like horror. He felt the tension—the fear—of his bridge crew as that incredible missile just kept coming for them. And then, nine impossible minutes after launch, it streaked directly past Harpist—still under power, still able to execute its final attack maneuvers—and detonated harmlessly a hundred and fifty thousand kilometers ahead of her.

Italics are the author's.

For the above scenario, any use of missile sprint capability would deprive the SLN command crew of the time necessary to let them know just how outclassed they were--and to initiate yellow and brown stains in their pants.

As far as any kind of sprint capability for RMN missiles, if they have it, it should be reserved for when it is truly needed--you don't give the enemy any chance to know that much about your capabilities in advance of when you either truly need it to survive (Operation Sanskrit) or are ready to pull the trigger on a massive attack (Operation Buttercup) unless you absolutely know that he can't get away to tell others about them.

Finally, you wouldn't necessarily want an AI to choose when to initiate sprint, because time-on-target (where all missiles attack at once or very nearly at once) is necessary to overwhelm point defense (CMs & PDLCs), preventing your attack from being defeated in detail.

Besides.
That Sprint concept was a poor attempt to try and match Many missiles that were already behind the SOTA.

Vince wrote:

cthia wrote:I certainly agree with you for the most part, Bluesqueak, however, I think you and I disagree on what is actually considered "copious" amounts of drive time left.

I'm specifically recalling the demonstration launch during SoV when the missile continued on, paraphrasing "...one minute...two minutes...three minutes...four minutes?," beyond targeted SLN ships, recognized by the frightened SLN CO.

I forgot the encounter. No time to look it up. Three or four minutes inside your missile envelop should cause the RMN AI to select available sprint mode. Certainly the AI can calculate :CONDITIONS :SPRINT MODE.

You mean this encounter, where all nine minutes of powered missile flight were used to chase down the SLN ship?

Shadow of Victory, Chapter 67 wrote:“I am Captain Aldus O’Brien, Royal Manticoran Navy, commanding Her Majesty’s Ship Trebuchet,” he said coldly. “I’m also the senior officer of Task Group Ten-Two-Eight, and my orders are to take or destroy any Solarian naval units in this star system. Be advised that you are now in range of my missiles.”
Despite himself, Ibañez felt his face tighten. It had almost certainly turned pale, as well, he thought. If O’Brien was telling the truth, his missiles had a range of over thirty-six million kilometers! It was true the Manties had built their overtake velocity advantage to over 30,000 KPS, which would boost their effective range significantly, but even so—!
“I realize you may doubt whether or not you are, indeed, in my range envelope. Accordingly—”
“Missile launch!” Lieutenant Commander Stedman said suddenly. “One missile closing at an overtake of one-three-six KPS squared!”
Ibañez watched the display as the single missile icon streaked after his ship. It accelerated fiercely, but it also had thirty-six million kilometers to go. The impellers on a Javelin, the SLN’s latest missile, would burn out three minutes after launch, which would have given an effective envelope of just under eight million kilometers from that geometry. It could still have caught Harpist, assuming no radical course changes on her part, but its overtake velocity when it did would have been down to a mere 5,000 KPS and it would have long since gone ballistic. That would have made it dead meat for point defense, nor would it have been able to execute any terminal attack maneuver to bring its laserhead to bear, which would have made the chance of actually hitting the ship nonexistent. But this wasn’t a Solarian missile, and his stomach turned into a hollow, singing void as it went on accelerating at 46,000 KPS2.
The Javelin’s acceleration was actually seven percent higher than that…but this missile accelerated effortlessly past the hundred eighty second-mark where a Javelin’s drive would have failed. Four minutes. Five minutes. Six minutes. Seven minutes.
He felt his jaw clamping harder and harder in something very like horror. He felt the tension—the fear—of his bridge crew as that incredible missile just kept coming for them. And then, nine impossible minutes after launch, it streaked directly past Harpist—still under power, still able to execute its final attack maneuvers—and detonated harmlessly a hundred and fifty thousand kilometers ahead of her.

Italics are the author's.

For the above scenario, any use of missile sprint capability would deprive the SLN command crew of the time necessary to let them know just how outclassed they were--and to initiate yellow and brown stains in their pants.

As far as any kind of sprint capability for RMN missiles, if they have it, it should be reserved for when it is truly needed--you don't give the enemy any chance to know that much about your capabilities in advance of when you either truly need it to survive (Operation Sanskrit) or are ready to pull the trigger on a massive attack (Operation Buttercup) unless you absolutely know that he can't get away to tell others about them.

Finally, you wouldn't necessarily want an AI to choose when to initiate sprint, because time-on-target (where all missiles attack at once or very nearly at once) is necessary to overwhelm point defense (CMs & PDLCs), preventing your attack from being defeated in detail.

Actually, you do want AI doing most of the work. That does not mean it does all the work. The tactical officer can set a lot up but the last second decisions when dealing with dozens of pods (which means hundreds of missiles) have to be set up. Since things change a lot during a battle, a series of possible choices would be set up for the AI.

cthia wrote:

Jonathan_S wrote:Could you add one to a normal Mk23? Certainly it seems you could replace the current 3rd drive with one; but that would actually reduce it's powered range and terminal velocity just to get more delta-v in the final 75 seconds of flight. That's probably not worth it.

Adding a 4th drive would require a larger missile (like the system defense missiles) or you'd have to pull a lot of other things out, and there's not much that could be downsized except # of laserhead and size of warhead. So even if you could cut those enough to squeeze a 4th drive into a missile of the same dimentions the reduction in damage doesn't seem worth the extra range and terminal velocity...

So basically I don't see it as worth while for the RMN to incorporate into their shipboard MDMs - and definitely not into their DDMs.

I'm not quite too sure about that Jonathan.

If the RMN could pull off at least a "sprint mode" made to work in conjunction with staggered missile launches, taking advantage of the weakness of point defense, I think would have an even bigger impact on its already devastating effect.

A sprint mode that kicks in right after the Dazzlers and Dragon's teeth spin up?

[snip]

I always thought it was a waste, for end of run missiles to complete their runs, with copious amounts of drive time left on tap. Can we utilize all of the remaining drive time in an all out burst?

I'm not sure it can be done. But I'm certainly sure of its proposed effectiveness, if used correctly.

Missile drive definitely can't use up their remaining time in an all out burst. That totally contradicts everything about how RFC set up missile drives to work. You can set their accel, but then they run until they burn out or you cut power. Either way you can't restart them. They'll almost always have "wasted" time at the end of run.


However, I went back and did some number crunching on a notional Mk23 that replaced the 3rd drive with a Mk31/Viper derived one (130,000 gees for 75 seconds) and got numbers that surprised me. I'd thought, based on the Cataphract, that the shorter duration of the Sprint drive would make the missile slower across the final 2 million km CM zone, but on a 3 drive missile the numbers don't support that. (Which I guess is why it's good to number crunch multiple scenarios)

As well there's an outside chance the higher acceleration might confuse a poorly programmed tactical computer, but honestly any computer updated to deal with the 0.8+c closing speeds of MDMs shouldn't have much issue tracking sprint mode drive. And any computer, like the SLN's current ones, already incapably of handling that closing speed can hardly be much less useful against a Sprint drive. But still, even without tac computers rejecting the missile as impossible, the better terminal acceleration could still help.


First, continuous powered range, with the stock Mk23 on the normal 9 minute half-power profile; these are terminal burnout numbers.
Stock - 540 seconds, 65,726,640 km, 0.81 c
Sprint - 435 seconds, 44,966,565 km, 0.86 c

Now some specific ranges. I'm picking a flight profile to minimize flight time, so at shorter ranges some drives may be high (H), some half power (L), the final sprint (S), and if necessary to make range a ballistic (B) segments. I won't list out all the details, but the summarized flight profile will be listed.

Code: Select all

Range  |    Conventional    |      Sprint
16m km | HHBH 192.9s 0.541c | HHS  182.2s 0.641c
32m km | HHL  293.3s 0.621c | HLS  312.7s 0.765c
48m km | HLL  409.3s 0.706c | HLBS 430.5s 0.770c
64m km | LLL  532.9s 0.801c | LLBS 552.3s 0.860c
72m km | LLBL 578.7s 0.812c | LLBS 601.6s 0.860c


I didn't explicitly calculate the time to cover the last 2 million km, but in all cases the missile is already under Sprint drive and given the better terminal velocities it's got to be quicker.

On the other hand beyond 45 million km, were the Sprint equipped MDM has to coast to make range the total flight time of the conventional MDM is lower, despite the slower terminal velocity. However even though that means the enemy could potentially blow up ships still controlling your initial missile salvo, being less than 30 seconds from impact the missiles should do pretty well on their own (a non-Apollo MDM would already be on it's own just due to lag, but Apollo round trip lag at 72 million km is under 8 seconds).

Hmm, as a whim I also looked at sprint - sprint - ballistic - sprint. That's a crazy capable missile.
Sure burnout is just 225s and 32,248,125km; but terminal velocity is 0.95c.

Add 208.1s of ballistic coast and you still reach 72 million km in just 433.1s; over 2 minutes (145.6 seconds) faster than a normal Mk23 and with 110% the terminal velocity! And it should be shorter flight time to any range


If Manticore can build it then all hail the new MSDM (multi-sprint drive missile)!

You cannot change the acceleration of a running missile drive. You can only shut it off before it burns out. To change acceleration you need to activate a second drive.