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Three-stage vs. two stage multidrive missiles

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Re: Three-stage vs. two stage multidrive missiles
Post by kzt   » Sat Dec 06, 2014 3:38 pm

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If it's an RMN one, the fact that it should be glowing like star from the reactor heat would allow high precision tracking. The whole mystical "we dump heat through the wedge" only works when there is a wedge up.
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Re: Three-stage vs. two stage multidrive missiles
Post by Relax   » Sat Dec 06, 2014 4:05 pm

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SWM wrote:I guess what you are saying is that it doesn't matter if the enemy can exactly predict 45 seconds in advance where to aim the counter-missiles?


Of course it doesn't matter. Do the simple math my man. A bit of work but easily doable long hand.

Do a time stamp interval calculation. Suggest using Excel to make it easier and less work. Do it in intervals. Heck, copy paste it in intervals of 0.1s or whatever update interval you choose. Check delta d. plot it. Assume MDM is accelerating away tangently 30 degrees. Assume CM accelerates tangently at 30 degrees. IE 46,000g verses 65,000g. Set time interval to total time delay(update + c lag from mother ship) before said CM starts to home on its next iteration. It makes a homing interception. Even if you only update the CM once a second. Of course CM has gravitic sensors as well and one has to guess when they start being more reliable than mother ship as we the reader do not know.

There is no reason to shoot 45s in advance. WEDGES are FTL. Longest time delay are RMN viper CM's at ~12s, but the error at this point is far lower as CM has its own sensors online at this point and homing in. What is up with the 45s doo hickey? 15Mkm/c? Doesn't apply as it is 15Mkm/62c = 0.8s and shrinking.

Roughest error patch for homing solution is about 2/3 distance before one "guestimates" CM "sees" its prey. Optimal timing for activation of Dragons teeth and Dazzlers =-)
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Re: Three-stage vs. two stage multidrive missiles
Post by Relax   » Sat Dec 06, 2014 4:09 pm

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SWM wrote:
What I'm talking about is predicting at T=60 seconds where the missiles will be at T=105 seconds (when you can fire your counter-missiles). If the attack missile is an MDM, you can only make a guess where the missile will be 45 seconds later. You can make probability estimates only, and calculate contingency allocations based on several options. On the other hand, if the attack missile is a DDM, you know EXACTLY where the missile will be at T=105 seconds; the second drive won't be starting until at least T=120. You don't need several options--you can immediately start calculating the optimal allocation of point defense.


Why the distinction between DDM/MDM? Only difference is closing velocity. Am I missing something here at what you are trying to get at?
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Re: Three-stage vs. two stage multidrive missiles
Post by SWM   » Sat Dec 06, 2014 4:10 pm

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Jonathan_S wrote:
SWM wrote:What I'm talking about is predicting at T=60 seconds where the missiles will be at T=105 seconds (when you can fire your counter-missiles). If the attack missile is an MDM, you can only make a guess where the missile will be 45 seconds later. You can make probability estimates only, and calculate contingency allocations based on several options. On the other hand, if the attack missile is a DDM, you know EXACTLY where the missile will be at T=105 seconds; the second drive won't be starting until at least T=120. You don't need several options--you can immediately start calculating the optimal allocation of point defense.

I guess what you are saying is that it doesn't matter if the enemy can exactly predict 45 seconds in advance where to aim the counter-missiles?
On the one hand, the MDM is under power and can manouver, so it can actively run a somewhat evasive routing - so I agree you can't predict exactly where it will be 45 seconds later. On the other hand it's getting steadily closer and you're getting a solid and improving look at it's wedge, so you can track it better.

The missile coming in ballistic is moving on a predicable path (assuming it can't cheat a little with reaction thrusters of some kind), so if you had its vector nailed perfectly when the drive went down you could predict its future location virtually indefinitely far into the future (until it brings it's drive back up)
But there are two sources of error in that prediction; one I already touched on, you can't know exactly when it'll bring the drive back online - if it does so sooner than you expect then it won't be at the predicted intercept point for your CM (however it'll be trackable again). The other is that when the drive cut out it was probably quite far away from you - you likely had some error bars around your lock on its vector. So the longer it coasts the less accurately you know where it is (The 95% confidence zone volume keeps growing because it might have aimed been a a degree or two to the left, right, up, or down of where you though it was pointing, or a fraction of a percent faster or slower.)

However, Relax is essentially saying that, statistically, you can narrow those error bars to near zero.

And the DDM can't start its second drive early--if it does, it won't have any drive left when it makes final approach. It could start the drive later, but not earlier.
Last edited by SWM on Sat Dec 06, 2014 4:29 pm, edited 2 times in total.
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Re: Three-stage vs. two stage multidrive missiles
Post by SWM   » Sat Dec 06, 2014 4:22 pm

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Relax wrote:
SWM wrote:
What I'm talking about is predicting at T=60 seconds where the missiles will be at T=105 seconds (when you can fire your counter-missiles). If the attack missile is an MDM, you can only make a guess where the missile will be 45 seconds later. You can make probability estimates only, and calculate contingency allocations based on several options. On the other hand, if the attack missile is a DDM, you know EXACTLY where the missile will be at T=105 seconds; the second drive won't be starting until at least T=120. You don't need several options--you can immediately start calculating the optimal allocation of point defense.


Why the distinction between DDM/MDM? Only difference is closing velocity. Am I missing something here at what you are trying to get at?

Yes, I think you are missing it. When you fire your counter-missiles at the DDMs, they are still ballistic. You know where they are because you were tracking them when the drives shut down at T=60. And you have known since T=60 exactly where the missile would be when you fired your counter-missiles. You have had all the time since T=60 to figure out the best allocation of point defense. If they were MDMs, you would not know how to allocate point defense until just before you fired counter-missiles.
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Re: Three-stage vs. two stage multidrive missiles
Post by Relax   » Sat Dec 06, 2014 4:34 pm

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SWM wrote:Yes, I think you are missing it. When you fire your counter-missiles at the DDMs, they are still ballistic. You know where they are because you were tracking them when the drives shut down at T=60. And you have known since T=60 exactly where the missile would be when you fired your counter-missiles. You have had all the time since T=60 to figure out the best allocation of point defense. If they were MDMs, you would not know how to allocate point defense until just before you fired counter-missiles.


It makes no difference. Total missiles incoming is all that matters. Doesn't matter if active drive or ballistic. Allocation "time" of 0.000000001s is a joke as a stumbling block. The computer is not reinventing the wheel against each and every missile. Doing so will not achieve a better solution than a look up table. Missile defense will be based on look up tables based on the incoming parameters. In the heat of a battle is not a time for tweedle dum and tweedle dee to start prognosticating and wondering if we did 'x', what do ya think Bob? Everything is set in ceramacrete at least in simulation if not at the crusher. Only minor carefully delineated adjustments via humans are allowed.
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Re: Three-stage vs. two stage multidrive missiles
Post by Vince   » Sun Dec 07, 2014 1:11 am

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kzt wrote:If it's an RMN one, the fact that it should be glowing like star from the reactor heat would allow high precision tracking. The whole mystical "we dump heat through the wedge" only works when there is a wedge up.

If I take your statement to its logical conclusion, a fusion powered DDM/MDM that is coasting ballistically (without a wedge up to dump heat to) will not just glow like a miniature star, but will eventually get to the point where the reactor will loose containment from loss of structural integrity because the missile's fusion reactor material(s) melting point(s) were reached or exceeded (because the missile can't dump heat fast enough without the wedge up), assuming that the reactor doesn't run out fuel first.

At which point the missile becomes a very fast moving, although very small, nova. And the whole idea of ballistically coasting dual or multiple drive fusion-powered missiles goes out the airlock. Although capacitor-powered missiles might be able to make it work.
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