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-   -   Kinetic kill missiles (http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=37518)

Carlobrand April 10th, 2017 10:37 PM

Kinetic kill missiles
 
I need a consensus on a point. Translating HG to Mega has the missile problem: to hit in the same round, as in HG, they have to achieve some uberrific speeds, which essentially makes them kinetic kill vehicles. Now, it's actually possible to design one of those given the Hard Times rules, range of a bit under a hundred thousand klicks, if one starts from certain assumptions:

First, the fusion drive does not seem to have a minimum size. I'm thinking it should, but it doesn't, unless there's been some change or I missed something. The fusion drive offers the only known drive capable of those ranges that will fit in a missile frame - if it doesn't have a minimum size that renders it too big. More on that point later.

Second, guiding the missile to target is most reliable if you use a laser comm and allow the launching ship to direct it. However, that requires the assumption that a short-range laser comm can accept signals from a longer-range laser comm, even if it can't return them. Otherwise, the comm becomes a very expensive bit of equipment for what is supposed to be a 20 kilocredit missile. I have a vague idea that this is acceptable but I don't recall seeing an actual rule.

Third, if I understand the physics correctly, this thing is impacting with enough energy to carry it through any level of armor MT is providing - and out the other side, at the longer ranges. It's looking like it's basically "drilling" a hole through the ship, vaporizing itself and anything in its way like a worm from the depths of hell, which is a lot more deadly than any traditional missile is capable of, but if it's possible to do it with a fusion drive and a laser comm, I don't see any reason they wouldn't. I'm not seeing a boom, but I am seeing something that basically hits the damage table without bothering to consider what the armor of the target is, because it's so overpowered it's just going out the other side.

Am I misinterpreting something here? Have I misunderstood the physics?

kilemall April 11th, 2017 03:50 AM

Have no idea about MT rules, scale, time per space move/fire round etc.

But can speak to what I would expect of a primary kinetic weapon.

I would expect that the average missile would play to percentages and fire a warhead that operates on a shotgun/AA shell concept- flying fragments that count upon velocity to kill and a large cloud to increase the chances of a hit.

Moreso if the detonation can be done effectively out of close PD range, so all that can be shot at are thousands of fragments.

The Casaba Cannon mentioned in the nuclear warhead thread would be another way to put velocity to use.

http://www.projectrho.com/public_htm...gunconvent.php

finally, if you insisted on running a missile directly into the enemy ship and were concerned about the kinetic impact being wasted, I would expect such a missile would be designed like a bullet to tumble, break apart and deliver energy to create a maximum 'wound cavity' to gore the insideof the target ship.

infojunky April 11th, 2017 04:32 AM

Quote:

Originally Posted by Carlobrand (Post 563444)
I need a consensus on a point. Translating HG to Mega has the missile problem: to hit in the same round, as in HG, they have to achieve some uberrific speeds, which essentially makes them kinetic kill vehicles.

I think you are failing to notice that both High Guard and MegaTraveller following are both Fleet Combat systems. As such their handling is very abstract at best.

As for the guidance, a receiver, how big does it need to be?

And considering if the model you are using is a one turn burnout, you probably would be safe assume that you have enough energy to KO any conceivable target. Though to be honest there are no stated ranges in High Guard.

Carlobrand April 11th, 2017 06:45 AM

I have in fact noticed that, yes. Noticed it about 34 years ago, I believe. Also noticed that it was ported more or less verbatim into MegaTraveller, which very much does not use abstract ranges. That would be why I'm posting in the MegaTrav group, as opposed to the CT group.

For those unfamiliar with MegaTraveller, as I said it pretty much lifts the High Guard rules verbatim and adds a few flourishes like sensor detection and sensor lock. Time scale is the same, 20 minute turns. It uses a mapboard with 25,000 km to the hex scale - which is a math fail given the time scale, but MT is infamous for errata, so put that aside for the moment. Short range per game rules is 50,000 km, long range is anything past that, and there's no stated limit to maximum range: so long as you can get a lock, you can fire. You can get a lock to rather impressive ranges with a Model 9 computer and the best available sensors.

Even given the Rules-as-Written time and distance scales, missile impact speeds are tremendous: to get impact in one turn per rules requires about a 14G missile if you assume a 100,000 km maximum range, 21G at 150,000, and so forth. The 14G missile is actually plausible under Hard Times design rules, and it's hitting at 83 kps after just 25,000 km, so definitely a kinetic kill weapon. Impact energy at 83 kps is 3444.5 megajoules per kilogram impacting, a couple orders of magnitude greater than you'd get out of an HE warhead that could fit that missile. At that speed, it's basically punching a hole through any amount of armor a game ship can mount within the rules.

That leaves my original question: am I interpreting the rules and the physics correctly?

mike wightman April 11th, 2017 08:58 AM

I just can not reconcile how the 50kg standard missile can have the performance it does.

Carlobrand April 11th, 2017 01:35 PM

I can't make one that hits all the points. Using Hard Times, I can make a 50 kg missile reach about 150,000 km in one turn, but because hydrogen is light it's about 3-4 times the size of the missile in the rules. I can alternately make one the right size - its range is a bit under 100,000 km in one turn - but it's much lighter than the game missile.

Assumptions are:
That a fusion drive can be made that small - rules allow it but it seems wrong given that power plants have a minimum size.
That a 5km laser comm can pick up signals from its larger cousins so the ship can guide the missile, even if its range won't let it send responses back to the ship. Otherwise, any missile needs some very expensive comms or sensors.
That a KKV behaves the way I think it behaves when impacting at that speed.

And, yes, having it split into multiple impactors would definitely make it more deadly - but it's already wicked deadly. Multiple unmodified damage rolls from one hit with a turret-launched weapon would radically change the game, rendering anything bigger than a destroyer obsolete.

Of course, if you like a small ship universe, this is the way to do it.

aramis April 11th, 2017 01:47 PM

Carlo: keep in mind that the design sequences assume a drive that can be worked upon in place. One can, without bending the rules too far, reduce the volume of the drive (but not the mass) by about 50%.

Some fan-done assessments imply that half the mass or more of a fusion drive is the shielding to prevent killing the engineers with the radiation. That would pull another 10% of the basic volume off (so we're now down to about 40% vol, and 50% mass).

Take some shortcuts and remove redundancies for single use drives... probably shave another 30% mass and 15% base volume. (Down to 25% base vol, and 20% base mass.)

whartung April 11th, 2017 04:16 PM

As always, I find space combat with a mix of ballistic weapons and light speed weapons incompatible.

Partly because of the "kinetic kill" weapon, considering the speeds these ships flit about the solar system, almost any impact of any size is truly devastating, combined with the problem that there's not much you can do to prevent it.

But if you have light speed weapons, particularly that are effective the ranges posited in Traveller games, then kinetic weapons are essentially dead in the water, as a simple drive hit will disable the weapon (against a maneuvering target), and these shots can happen at range.

Naturally, in such a case, you "simply" overwhelm the point defense with a swarm of KK weapons, and thus now comes to the game the issue of balance. How many KK weapons can be deployed, how many effective shots can the light speed weapons take, etc. You may be able to try and spoof the KK weapon, perhaps through ECM or some other technique.

But, in the end, KK tend to be quite lethal, in terms of bang/buck, and you either have lots of ships to make a lot of targets, or you make behemoths that can actually absorb the monster hits that the KK weapons can inflict. But if you go that road, they still can't absorb many.

Which circles back to the basic lament of space combat being little more than rifleman standing in a bull ring.

Carlobrand April 11th, 2017 09:19 PM

Yeah, you do get that circular firing squad effect going.

Quote:

Originally Posted by aramis (Post 563492)
Carlo: keep in mind that the design sequences assume a drive that can be worked upon in place. One can, without bending the rules too far, reduce the volume of the drive (but not the mass) by about 50%.

Some fan-done assessments imply that half the mass or more of a fusion drive is the shielding to prevent killing the engineers with the radiation. That would pull another 10% of the basic volume off (so we're now down to about 40% vol, and 50% mass).

Take some shortcuts and remove redundancies for single use drives... probably shave another 30% mass and 15% base volume. (Down to 25% base vol, and 20% base mass.)

I'm looking at that. It seems like they already took some of that into account.

At TL9, minimum size power plant is 10 m3, masses 40 tons, puts out 20 Mw, and cost MCr2.

The TL9 fusion drive is 1 m3, masses 4 tons, puts out 3.95 Mw plus I think dumps 0.195 Mw into thrust, and cost MCr0.35.

Scaling the fusion drive up to more or less match the power plant output, multiplying everything by 5, and you get:

5 m3, masses 20 tons, puts out 19.75 Mw or 20.475 Mw if you try to count the exhaust, and cost MCr1.75.

It looks very much like a power plant that they pulled the shields and cooling system off and replaced with a hydrogen feed to cool the plant and provide thrust at the same time. Of course, that's very approximate, but it's interesting that the base drive at 1 m3 appears to be 1/5 what would be considered minimum size in a power plant.

And it makes a dandy replacement for the power plant/maneuver drive if you want a fusion drive ship.

kilemall April 12th, 2017 01:11 AM

Quote:

Originally Posted by Carlobrand (Post 563469)
I have in fact noticed that, yes. Noticed it about 34 years ago, I believe. Also noticed that it was ported more or less verbatim into MegaTraveller, which very much does not use abstract ranges. That would be why I'm posting in the MegaTrav group, as opposed to the CT group.

For those unfamiliar with MegaTraveller, as I said it pretty much lifts the High Guard rules verbatim and adds a few flourishes like sensor detection and sensor lock. Time scale is the same, 20 minute turns. It uses a mapboard with 25,000 km to the hex scale - which is a math fail given the time scale, but MT is infamous for errata, so put that aside for the moment. Short range per game rules is 50,000 km, long range is anything past that, and there's no stated limit to maximum range: so long as you can get a lock, you can fire. You can get a lock to rather impressive ranges with a Model 9 computer and the best available sensors.

Even given the Rules-as-Written time and distance scales, missile impact speeds are tremendous: to get impact in one turn per rules requires about a 14G missile if you assume a 100,000 km maximum range, 21G at 150,000, and so forth. The 14G missile is actually plausible under Hard Times design rules, and it's hitting at 83 kps after just 25,000 km, so definitely a kinetic kill weapon. Impact energy at 83 kps is 3444.5 megajoules per kilogram impacting, a couple orders of magnitude greater than you'd get out of an HE warhead that could fit that missile. At that speed, it's basically punching a hole through any amount of armor a game ship can mount within the rules.

That leaves my original question: am I interpreting the rules and the physics correctly?

For figuring out effective missile range, don't forget imparted velocity from the launching ship and closing speed of the target, positive or negative relative to the missile's impact vee.

That 'range' could easily double or triple, and have that much more damage potential.

As to the PD game on the terminal run, a terrifying option might exist if this is using HG. To wit, a fighter could be coming in at an effective velocity of say 20Gs, launch at 8 hexes or 200,000 km if I have this scale right, the 21G missile does 7G accel and 14 agility dodge while the fighter goes full agility dodge too as it comes through the close-in countermissle/beam weapon fire.

That could be a VERY tough missile to hit, at range or close-in until the last few seconds, and the fighter may or may not get away scot-free.

Again don't know the rules, just extrapolating from the HG comments.

Don't forget letting the missile drift for extra range with imparted vee, if you crave the play and are willing to track. At that point the target ship can literally maneuver out of the missile's potential intercept envelope, if the target's side can detect the missiles at range.


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