Point Defense Alternative

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phavoc
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Point Defense Alternative

Postby phavoc » Thu Dec 10, 2015 3:49 pm

I have been mulling over point defense for a while. I've never been a big fan of using the ships' lasers to shoot down tiny objects, nor allowing gunners the ability to use their skills in shooting them down. They should be travelling far too fast for human response - it would be more luck than skill if they were able to hit something.

Point defense should really be an automated affair. The bigger question though is how do you implement it without totally breaking the missile/ship combat rules. So here's (another) alternate stab:

Point defense systems may be deployed 1 per 500 tons of hull size. It consists of multiple weapon installations, sensors and targeting units spread over the hull of the ship. Different versions are:

TL-10 Point Defense System: Consumes one point of power and two hardpoints. Intercepts 1d6+2 missiles or torpedoes on final approach. For incoming fire that is of the stand-off variety effectiveness is halved.

TL-12 Improved Point Defense System: Consumes three points of power and two hardpoints. Intercepts 1d6+4 missiles or torpedoes on final approach. For incoming fire that is of the stand-off variety effective is halved.

TL-15 Enhanced Point Defense System: Consumes five points of power and three hardpoints. Intercepts 2d6 missiles or torpedoes on final approach. For incoming fire that is of the stand-ff variety effectiveness is halved.

The idea is that if you are willing to give up offensive firepower for dedicated defensive power you should be somewhat rewarded. The TL-15 version gives up guaranteed hits for more potential hits, but also bad rolls mean more missiles can possibly get through.

This also differs from the existing rules by (a) removing gunner skills and (b) making it an all or nothing approach. Plus you are limited by hull tonnage on what you can do with it. It would be possible to shoe-horn this into the existing point defense rules as well. And I don't think it's terribly lopsided against missile strikes. It does make for an attractive system for say escorts and the like whose primary job it is to offset the new danger for incoming missiles. Power is relatively minor as it should be for such a system. It would also be easy enough to create a lower than TL10 system that uses actual projectiles to destroy incoming missiles if that was so desired.

Now to figure out how to shoehorn in an anti-missile missile system.
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Re: Point Defense Alternative

Postby madmike » Thu Dec 10, 2015 9:36 pm

I introduced point defence systems in Anderson and Felix Guide to Naval Architecture. Worth a look for another alternative.
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Re: Point Defense Alternative

Postby crazy_cat » Fri Dec 11, 2015 5:21 pm

Statistically isn't the TL 12 verion better than the TL 15 one proposed. Average of 7.5 intercepts to 7 for the higher TL one?

Maybe 1D6+2 / 1D6+4 / 1d6+6 ?
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Epicenter
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Re: Point Defense Alternative

Postby Epicenter » Fri Dec 11, 2015 6:57 pm

I tried making an anti-missile system for a different game system, but seeing your thread, there's something I miss in Traveller: Tech Levels.

Technology Levels is a fascinating toy for these kinds of systems, but it also has issues with "why would anyone use a lower tech version when a higher tech one exists"? That it is attractive to use low-tech electronics in Traveller over high-tech stuff is one of fundamental flaws with the TL equipment system in Traveller I think. I'm old enough (unfortunately) to have been a kid during the 1980s - there used to be gas stations with garages everywhere because cars back then were that unreliable and maintenance hungry. In Traveller meanwhile, a car with early 1980s technology would somehow be more attractive than a 2015 car ... even though advances in technology have made 2015 cars cheaper, more resource efficient, and less maintenance hungry.

I think your PD system might benefit from playing with TLs more.

Just tossing out ideas here, how about something like this?

* Players love to roll dice. So I think that a human gunner couldn't shoot down missiles, but the PD would have a skill level so the players could roll dice and feel more in control of their fates.

TL10 Basic Point Defense System
Power Requirement: 5, Hardpoints: 3, Tracking Limit: 2, Gunnery Skill: 3

TL11+ Defense System
Power Requirement: 3, Hardpoints: 2, Tracking Limit: 4, Gunnery Skill: 4

Tracking Array Enhancements exist: It would require an additional Hardpoint and increases the tracking limit by 2. These can be bought without limit.

The PD systems require periodic maintenance. This must be done at a facility with a TL equal to or above the TL of the system. This make the lower-tech systems attractive in that a starship operator, particularly a private one (like players) can do maintenance on their systems in a variety of facilities. Similarly, a "frontier cruiser" might install a lower-tech PD, trading off effectiveness of the system (that probably won't be used often) in return for ease of keeping it running. Beyond that, higher tech versions are always better.

PDs exist at TL11, TL12, TL13, TL14, and TL15. However, their basic stats are identical when firing at missiles of their own TL. It's assumed that countermeasure/survivalability features exist in missiles meanwhile PD systems gain superior sensors, higher resistance to ECM, and so on. In game terms, the tech level race is abstracted so that if the incoming missiles are the same TL as the point defense, the basic statline is used.

A lower-tech PD is firing at missiles that are higher in TL subtract one from the gunnery skill for every TL difference. A result under Gunnery-0 means the PD attempts to attack the missile but automatically misses -- it's possible that an old, outdated PD will be totally ineffective against new hotness.

A higher-tech PD is firing at missiles that are lower in TL add one to the gunnery skill of the PD for every TL difference. A result of Gunnery-7 or better on the part of the PD means no roll is required, the missile is automatically hit as the PD finds it no more difficult to hit the missile than it would just a piece of space debris.
dragoner
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Re: Point Defense Alternative

Postby dragoner » Fri Dec 11, 2015 8:58 pm

phavoc wrote:I've never been a big fan of using the ships' lasers to shoot down tiny objects, nor allowing gunners the ability to use their skills in shooting them down. They should be travelling far too fast for human response - it would be more luck than skill if they were able to hit something.
This is firing upon another ship at thousands, or tens of thousands of km as well; the system is firing after it computes a solution, the operator element is more monitoring the situation.
Point defense should really be an automated affair.
Which would be allocating the lasers in your weapons suite to defense from offense. I find that missiles would be used in anything less than full barrage fires to be unrealistic. Cherryh's books did it best imo, weapons people manned the "armscomp".
phavoc
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Re: Point Defense Alternative

Postby phavoc » Fri Dec 11, 2015 11:29 pm

It's really should be more of a CIWS sort of engagement. Operator activates and tries to prioritize incoming targets, but like you said they should be coming in large waves to overwhelm defenses.

I liked the Cheryh universe too for its combat. There jumps were hard on the crew and ships, so it made for interesting combat.

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dragoner
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Re: Point Defense Alternative

Postby dragoner » Sat Dec 12, 2015 12:16 am

IIRC, the US Navy calls it "roll back" in SEADS (Suppression of Enemy Air Defense Systems) warfare.

Yes, the operator prioritizing targets, and using the ability to infer the developing situation, to draw the proper conclusions, something the computer usually lacks unless some advanced AI. This still gives room for gunnery tasks, without representing things like with a WW2 bomber turret or something.

Lasers seem natural for it as well, as they fire at the speed of light, missiles and other spacecraft would be moving slowly in comparison.
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Re: Point Defense Alternative

Postby phavoc » Sat Dec 12, 2015 2:32 am

Computers should have the professing power to do all that with only the human offering intuition and experience at a higher level. But essentially the fire consol systems have to do the actual engagement and such. One thing space navies don't have to worry about is missile s popping up with little to no warning due to curvature of the earth. There's no real way to hide an active missile or star drive if it's trying to hit you.

Lasers make great point defense weapons due to their high ROF and speed. Anti-missiles would make great interceptors too.
phavoc
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Re: Point Defense Alternative

Postby phavoc » Sat Dec 12, 2015 2:32 am

Computers should have the professing power to do all that with only the human offering intuition and experience at a higher level. But essentially the fire consol systems have to do the actual engagement and such. One thing space navies don't have to worry about is missile s popping up with little to no warning due to curvature of the earth. There's no real way to hide an active missile or star drive if it's trying to hit you.

Lasers make great point defense weapons due to their high ROF and speed. Anti-missiles would make great interceptors too.
dragoner
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Re: Point Defense Alternative

Postby dragoner » Sat Dec 12, 2015 3:01 am

phavoc wrote: One thing space navies don't have to worry about is missiles popping up with little to no warning due to curvature of the earth. There's no real way to hide an active missile or star drive if it's trying to hit you.
Unless it from behind a star, or planet, in an asteroid belt, gas giant's rings or a nebula. While tanks are given the dubious honor of being able to fight out in the open, it's something you never really do, you use ravines as roads (gotta love tracks) and scurry from clumps of trees and behind hills, using built up areas as redoubts, etc. . In space, I'm sure there will be similar tactics, like hey that solar wind with ionizing radiation that is scrambling your sensors? There's some missiles in it. Use of terrain has always been tactic.

In the game I'm GM of, we went through a battle in the atmosphere of a gas giant recently, that was different.
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Re: Point Defense Alternative

Postby Epicenter » Sat Dec 12, 2015 5:19 am

dragoner wrote: Unless it from behind a star, or planet, in an asteroid belt, gas giant's rings or a nebula.
Gas Giant's rings I think might be a chaotic environment.

A Star Wars style asteroid belt would be severe as well - but a realistic asteroid belt would be so diffuse it'd be the same as flying through open space.

A realistic nebula is so diffuse you wouldn't notice it if you were flying through it - they only look like dense, opaque clouds because we're seeing them from a huge distances. I think a dust/gas cloud of a protostar / protostar system might have areas that are pretty opaque though.

A missile that could surprise you flying out from behind a planet or a star I think would have to be traveling close to the speed of light - and would "surprise" you even in open space as a function of the speed it is moving, not because of "cover" - stars and planets are huge.
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Re: Point Defense Alternative

Postby dragoner » Sat Dec 12, 2015 6:21 am

Moving near C, you would find things a lot less diffuse, even with shielding, it would probably have a plasma cloud around it. Even diffuse, an asteroid, or planet, etc. creates a shadow relative to your position. Planets esp. could be a chaotic environment, depending on how much stuff is in orbit. Velocity is relative, the whole solar system is moving at 68,000 mph or so, tracking that, and at distance, multiple objects. I doubt battles will be picked to be standing out in the open.
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Re: Point Defense Alternative

Postby Condottiere » Sat Dec 12, 2015 8:24 am

Generally, it's the possession of or access to some piece of strategic real estate.
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Re: Point Defense Alternative

Postby Epicenter » Sat Dec 12, 2015 5:57 pm

dragoner wrote:Moving near C
You'll have to pardon me a bit, the idea that reactionless thrusters would allow you to accelerate to a significant percentage of the speed of light in a short period of time (and I fully admit they could in the abstract way they're written in Trav) really bugs me because it's a huge can of worms, even outside of "every scoutship becomes a planetbuster."

For instance:

I would think if you can throw a missile at "near C" velocities, you don't need to hide behind a planet or anything else. Every attack becomes a surprise, regardless. The surprise comes from the fact the missile is moving so fast unless you detect it multiple light-seconds away, it'd be un-interceptable; the missile is moving nearly as fast as the sensor return. If a missile is moving something like a paltry 0.7c (most speed demons when speaking of "near C" velocities they're talking about faster than that) and was fired from one light second (299,792km) away, you'd have 0.3 seconds to fashion a response.

Humans couldn't be involved in such a loop, it'd have to be automatic (which I think is fine).

However, I doubt there's a mechanical turret that could rotate and stabilize its own motion to focus fire on a missile with just 0.3 seconds response time. The solution might be to use a static mount laser and adaptive optics which bounce the beam around until it's at the right angle. This way each reflector only needs to angle the beam some fractions of a degree. Of course the problem with such a reflector is that if you could make reflectors that could bounce around a destructive beam like that, wouldn't everyone use it on the missiles and their starships? So maybe you'd use multiple low-power lasers that all focus their fire incoming missile to overcome its laser-resistant skin. Maybe that'd work - though could it "burn through" the missile's skin before it the missile does whatever it does? What if I surround my missile with multiple very thin shells (lightweight!) of this laser-resistant material that ablates away, carrying away the energy of the lasers - if the shells even last for 0.2 or 0.1 of a second, it'd probably be long enough for an actual impact. (Obviously, you could use some transparent medium as laser direction changes - refracting the light just slightly - but then I could surround the front of my missiles with static lenses that'd direct the laser light away from my missile - even if the lenses break or vaporize after a moment, it'd probably still be long for the missile to hit.)

Then there's computer processing to take into account - the time it takes to gather sufficient sensor data to decide if the return is actually a threat, a piece of space debris, or even some sensor error. If the defense system simply fires a response at any return, that CIWS system becomes awfully twitchy and hazardous but if you add in a IFF the response time slows down. The system would have to be fast enough to take in the data, analyze it, then set up the CIWS system.

I'm not sure that could all be done in 0.3 of a second.

(Even two light seconds @ 599,584km would yield 0.6 seconds response time vs. a 0.7c missile. I think that's still pretty iffy, while ~600,00km is a goodly distance for space combat. Maybe around three light seconds out, the slowpoke 0.7c missile finally gives you 0.9 seconds response time, which would allow for interceptions, but at that point the firer can be ~900,000km out. If these theoretical near-C missiles travel faster than 0.7c the problems become even worse.)
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Re: Point Defense Alternative

Postby dragoner » Sat Dec 12, 2015 7:26 pm

Epicenter wrote: snip ...
People are taught about space wrong, it isn't empty, just less dense, such as our atmosphere is less dense than down below the crust of the planet, all perfectly orderly and logical. The universe is more like a liquid, or a foam; Newton had stated that his idea of the Earth spinning in nothing, was a simplification, and beyond dust or molecular hydrogen, there are quantum fields. Anything moving near C would have a nimbus around it at least, from impacts, if one wants to see clouds of plasma generated by velocity, the US Navy's recent test of a rail gun is a good example.

Like I said: "I find that missiles would be used in anything less than full barrage fires to be unrealistic." near C or not. The sensor issue you mention can be solved by having drones spread out as FO's providing a continuous feed, at least at such velocity, I could see how a lone missile could get through, laser still has the advantage though. There is a good quote from the Forever War, about how much you can stuff in a satellite the size of a grape, a miniaturized cavity magnetron and transmitter you probably could put in it easily enough, the transmitter minimal watts anyways, to not show itself off.

Beam weapons, would be completely different. Here is a few mind blowing ideas: sit behind a planet, use an FO boat or something, and use gravity lensing to curve the beam around the planet. Which bring up planets, look at the increase in orbital objects in just a few tech levels, now, in real life. Using that as an example, where every increase is an order of magnitude, there could easily be tens to hundreds of millions of objects in orbit. Add to that a missile barrage of a million missiles rising from the planet, or thousands of the highest n number deep meson gun sites; I'm not sure how planet get taken, plus they can hold out forever, we have (and do). Meson guns, beyond lensing, a meson gun equipped ship could sit behind a planetary body, use FO's and shoot directly through the planet, never exposing itself. Which even normal ships can "pop up" and fire from behind a smaller object, then retreat back behind. One thing I have thought of missiles for is as scatter-able space mines, just throw a billion or so out there, if the target doesn't show a friendly IFF tag, fire them up.
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Re: Point Defense Alternative

Postby phavoc » Sat Dec 12, 2015 8:55 pm

Deeps it planetary meson guns are what you are talking about, and literature about them had them using external sensors to track and attack craft in orbit. Their Achilles heel being blinding the sensors they need to shoot, and the power requirements they need are pretty massive. Taking them out has always been a challenge.

But the rule rewrite makes planetary meson sites questionable. Meso guns are now spinal only mounts, which could theoretically be mounted underground. The rules for planetary defense have never been well detailed. Coacc had attempted to do some of that.
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Re: Point Defense Alternative

Postby dragoner » Sun Dec 13, 2015 8:12 pm

We're kinda off target with planetary sieges, though missiles are sort of a thread in which the cloth of space battle rules are written.
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Re: Point Defense Alternative

Postby phavoc » Mon Dec 14, 2015 12:57 am

I only mentioned the new quirk in the meson rules since it was brought up.

Not sure about a "million" missiles. That would be a pretty heavy dent in any planet's pocketbook. And you really can't hide behind a planet - it's far too easy to send scouts 'above' or 'below' the planet to see what is there. Or recon drones/probes. Military vessels expecting combat or on heightened alert should always have recon vehicles or drones out ahead of them looking for lurking craft or other things. That's something that's never really been explored within Traveller, nor have advanced missile systems. We are still stuck in the mindset of the 1970s (for both offense and defense).

I guess you might compare Traveller missile/torps to what you saw in early sci-fi shows. The original ST show had starships with relatively slow firing rates. When you moved up to the later years of ST-TNG or DS9 you saw very rapid firing photon torpedo launchers. Space combat in those shows was very fast paced. As I mentioned up-thread, Traveller space combat is more along the lines of WW1 capital ships duking it out with battles lasting hours. Today two fleets would attack at missile ranges and rarely close to gun range. It's pretty much whoever can overwhelm the other side first and do the most damage will win the skirmish.
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Re: Point Defense Alternative

Postby dragoner » Mon Dec 14, 2015 9:20 pm

phavoc wrote:Not sure about a "million" missiles. That would be a pretty heavy dent in any planet's pocketbook. And you really can't hide behind a planet - it's far too easy to send scouts 'above' or 'below' the planet to see what is there. Or recon drones/probes. Military vessels expecting combat or on heightened alert should always have recon vehicles or drones out ahead of them looking for lurking craft or other things.
While a million missiles may seem hyperbolic, think of how much our world spends on weapons and war, and then what price freedom/defense? Actually pretty cheap with advanced manufacturing techniques and amortizing the cost over many years.

Once found out from being hidden, a planet would still be cover (heaven help the recon ships); such as there is small comfort in seeing the muzzle flash of enemy artillery that is beyond the horizon on the clouds above when the shells are raining down on you.
It's pretty much whoever can overwhelm the other side first and do the most damage will win the skirmish.
Sure, however, it would also balance out to who can take the most damage in fleet engagements.
That's something that's never really been explored within Traveller, nor have advanced missile systems. We are still stuck in the mindset of the 1970s (for both offense and defense).
Some people's mindset maybe, but ad hoc in games, not at all, we have always tried to incorporate advances in tech.
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Re: Point Defense Alternative

Postby phavoc » Tue Dec 15, 2015 2:28 pm

dragoner wrote:While a million missiles may seem hyperbolic, think of how much our world spends on weapons and war, and then what price freedom/defense? Actually pretty cheap with advanced manufacturing techniques and amortizing the cost over many years.
One thing that's never mentioned is maintenance on things like missiles. Sure the annual maintenance covers the launcher, but missiles need to be maintained too. As a game you need not simulate that aspect, but they still require testing, maintenance and repairs as needed. So that would increase the overall cost of things.

Another thing is that nobody is going to build just missile to protect a planet. You are far better off putting them off-world to not give the guy who holds the high ground excuses to bombard anything suspicious looking on the surface. Unless you don't mind massive ground destruction (as either attacker or defender).
dragoner wrote:Once found out from being hidden, a planet would still be cover (heaven help the recon ships); such as there is small comfort in seeing the muzzle flash of enemy artillery that is beyond the horizon on the clouds above when the shells are raining down on you.
Yes. But what provides cover for the defender also provides cover for the attacker for any non-Meson weapon or non-ballistic one. Like many defensive measures it can cut both ways.
dragoner wrote:Sure, however, it would also balance out to who can take the most damage in fleet engagements.
This brings up concepts of acceptable losses and such. As the attacker you will need to retain a certain amount of forces to hold your newly acquired territory. As the defender you pretty much fight till the end, breaking only to harass the enemy at a later date (ala SDB's). And not every attacker is going to be willing enough to sacrifice the majority of their forces for a pyhric victory. But you are right, there's a lot of balance and trade-offs to be considered.
dragoner wrote:Some people's mindset maybe, but ad hoc in games, not at all, we have always tried to incorporate advances in tech.
I was speaking more to the official canon rather than house rules. Many modify the game to meet their own ideals - which is great. It's always nice to have that done for you when you purchase a rule system however. :) Otherwise why buy when you can build your own (and populate with Middenface's artwork!)

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