Traveller warships are WWII navy, but without a major piece

[Carlobrand]

This is not generally true, though sometimes true. The majority of the time, we have to assume that fleets would only even run into each other near something of value---a planet. That means orbit. Even if not a majority, a substantial % of engagements. If you jump in across the system, then engagements only happen if both sides chose to fight. Closer in, you could possibly force one side to engage.

So anywhere near a planet, one side is effective stationary to start with.

Book 2 gives us two-lightsecond detection ranges for warships and scouts - 600 thousand klicks. Ships jump in at a minimum 100 diameters from the target world, which can be anything from 160,000 kilometers to 1.6 million kilometers. That means the fleet jumping in will often have no sensor contact with the fleet protecting a world, especially if the defending fleet is orbiting close and maintaining radio silence. If they're smart, that defending fleet WILL have sensor contact with the intruders, because they'll have some sort of satellites or patrol craft patrolling the jump perimeter for intruders. Patrol probably won't last long, but the defender will know someone's coming to dinner. At any rate, the image of one side sitting and waiting for the other to arrive can get a bit more complicated sometimes.

Missiles start with whatever velocity the launcher has, and even the little classic missiles can possible do 6g12 or better, right (with the supplement?).

Even at a total of 6 g-turns, a 10 gram penetrators will have 622MJ energy. Modern tank rounds are on the order of 10-13 MJ.

This will vary linearly with penetrator mass, so a 1 gram ball would be 6X more energy than getting hit by a DU round from an Abrams tank.

Realistically, ships cannot actually evade uniformly 6g in any direction (unless you assume a reactionless drive that can "thrust" in any direction). Even so, almost 2 decades ago we did the math, and they can disperse at a substantial distance away (we looked at missiles the size of aerial torpedoes dispensing traveller superdense bbs such that they would have 1 bb every X meters square if spread at whatever the distance was. I'll find my notes. Back of the envelope, at 352 km/s (6 gturns), the target can evade if already pointed 90 degrees to vector ~29m in 1 second. That's a detonation 352 km away assuming only a 60m diameter cloud of bbs with no chance of missing with all bbs (might only hit with 1, lol). Note that you can then adjust damage based on how possible/cost effective SD bbs are vs lesser materials (DU, tungsten, etc) to adjust the damage (handwaving RL metal vs SD is allowed, after all).

Book 2 laser effective engagement ranges are up to 250 thousand klicks; they can hit with some accuracy to twice that and might get lucky even farther. High Guard doesn't figure ranges beyond the abstract "short" and "long". MegaTrav - not clear if there's a limit, though they are a bit less accurate beyond 50,000 klicks; detection and weapon lock ranges can be a lightsecond or more, depending on the ship's computer and sensors and how many ships are involved.

You have a lot of space to travel in order to deliver your kinetic cloud to attack range. The enemy's going to be doing what he can to make sure you don't cross that distance, both by shooting at you and your missiles and by maneuvering himself. It's a cool idea but, as in all things weapons, the guy on the receiving end of it's going to be putting as much thought and creativity into keeping it from happening as you put into making it happen. The missiles have to cross tens of thousands of miles before they can achieve ranges that give them a reasonable chance at landing a "BB" on a target, and they have to survive laser bursts and blasts of "sand" that are basically trying to do to them what they intend to do to the target.

The other problem is that your 6G missiles are often encountering 6G targets. With potential engagement ranges of tens or hundreds of thousands of miles and ships as fast as the missiles, it becomes more like seagoing warships launching torpedoes at each other than like those same ships battling supersonic inbounds - a bit of forethought and luck can deprive the "torpedo" of the intercept entirely.

Mind you, I prefer to think of the missiles as hyper-G interceptors myself, works better with the High Guard combat paradigm than the 6G missiles, but it's not what the original stuff or the later MegaTrav wants to give us.

 

[mike wightman]

Ever read Mayday? It is supposed to model LBB2 combat and the later versions had conversion notes for adapting HG and HG ranges.

Take what it says with a pinch of salt, for reasons that should become readily apparent

HG short range - 5 light seconds, long range 5-15 light seconds.

4.5 million clicks weapon range

 

[tater]

The distance that a missile can be picked off is what I'm referring to. It has to be guided all the way to the target. I've done the calcs. The unguided perpetrators would have to be released TOO close to the maneuvering targets. It isn't viable.

1000s of kms away and still certain impacts from a single missile. A 100 ton bay worth? They can blanket future positions having some detonate at longer ranges. Assuming you spread them out such that fratricide is not a huge problem, you could have any missile blinded (that's a lot of what defensive directed energy fire will do, in fact, knock out sensors) disperse penetrators assuming it has a brain left (poll sensors, if down, boom!).

BTW, the "it isn't viable" argument presupposes that all ships are defensively armed for just such an encounter. If you operate under that assumption, and decide not to prepare, then your fleet is incredibly vulnerable (perhaps the problem the 3d Imperium had in Invasion Earth? ).

It also means that there are no such thing as effective nuclear missiles, since they need to detonate FAR closer than a KE missile needs to disperse penetrators (the only damage would be radiation unless a virtual contact hit). For a 20kt blast, assuming shielding on craft capable of dealing with only a few hundred rem (traveller ships likely far better shielded) a nuke that size needs to detonate within 20km to produce any exposure at all above background. For dangerous exposure, this needs to be under 10km away (and that's with shielding for maybe 300-400 rem solar flares, etc). So within 10km would be dangerous with a lightly shielded target in terms like "increased likelihood of later cancers" You'd need many nukes going off, or near-contact to produce immediately disabling effects on crew.

If nukes are used in traveller (they are), and they are dangerous to ships (they are), then detonation ranges inside 10km are cannon. Nukes and non-nukes are used in traveller at all levels of space combat. Either none every hit any target, or KE weapons are possibly very deadly, and certainly capable of hull scrubbing (many, many tiny pellets means less damage, with a higher chance to hit, which is a really nice reality to model for a game, actually, since it provides a great trade off of lethality vs lower chance to hit if you want to go that way).

 

[tater]

Book 2 gives us two-lightsecond detection ranges for warships and scouts - 600 thousand klicks. Ships jump in at a minimum 100 diameters from the target world, which can be anything from 160,000 kilometers to 1.6 million kilometers. That means the fleet jumping in will often have no sensor contact with the fleet protecting a world, especially if the defending fleet is orbiting close and maintaining radio silence. If they're smart, that defending fleet WILL have sensor contact with the intruders, because they'll have some sort of satellites or patrol craft patrolling the jump perimeter for intruders. Patrol probably won't last long, but the defender will know someone's coming to dinner. At any rate, the image of one side sitting and waiting for the other to arrive can get a bit more complicated sometimes.

Absolutely, detection ranges are long. Any ships near that planet are just as visible (except when behind it) to the attackers if they have the powerplant running, too (every watt generated has to be radiated to space, or the crew cooks).

Book 2 laser effective engagement ranges are up to 250 thousand klicks; they can hit with some accuracy to twice that and might get lucky even farther. High Guard doesn't figure ranges beyond the abstract "short" and "long". MegaTrav - not clear if there's a limit, though they are a bit less accurate beyond 50,000 klicks; detection and weapon lock ranges can be a lightsecond or more, depending on the ship's computer and sensors and how many ships are involved.

Yeah, things get messy in player vs fleet sized engagements, which books to use, etc. B2 produces different results than HG, and both are different from mayday, and 2 other options are HG with mayday movement, and B2 with mayday movement. Then there is B2 with the missile supplement (incredibly nasty missiles at the player ship level there). I'm taking about "fleet" level stuff, meaning military actions. I think for players, KE missiles are actually perfect, they offer a balance where you can hit more often, with less damage---disperse a lot of tiny bbs that do small damage (and the damage would be a function of closing velocity, need to make a simple table for that)---or more damage with it less likely to hit. I'd simply assume that the HG "hull scrubbing" cannon represents the happy medium navies come to for penetrator size, etc. on average. Some change in HG for a critical on targets above size 9 would make sense to me, however, to make missiles abstract in a more realistic way.

You have a lot of space to travel in order to deliver your kinetic cloud to attack range. The enemy's going to be doing what he can to make sure you don't cross that distance, both by shooting at you and your missiles and by maneuvering himself. It's a cool idea but, as in all things weapons, the guy on the receiving end of it's going to be putting as much thought and creativity into keeping it from happening as you put into making it happen. The missiles have to cross tens of thousands of miles before they can achieve ranges that give them a reasonable chance at landing a "BB" on a target, and they have to survive laser bursts and blasts of "sand" that are basically trying to do to them what they intend to do to the target.

The only maneuver that matters is the maneuvers the target does from the point the missile explodes or otherwise disperses the penetrators. Any missiles shot down before hand are gone. This is the "to hit" roll phase for the ones (if any) not destroyed. If the target can only displace itself 30 meters sideways before the cloud hits, if the cloud is at least 60m, it cannot miss. If the target is larger than 30m, it's is getting hit anyway, as well.

The other problem is that your 6G missiles are often encountering 6G targets. With potential engagement ranges of tens or hundreds of thousands of miles and ships as fast as the missiles, it becomes more like seagoing warships launching torpedoes at each other than like those same ships battling supersonic inbounds - a bit of forethought and luck can deprive the "torpedo" of the intercept entirely.

That is entirely addressed in the movement phase of the game, using B2, or Mayday for movement, the "to hit" only happens after intercept. Yes, that's a place for maneuver to matter, we're past that, however, we're talking about the handful that manage the task of interception (happens in all flavors of traveller space combat, they all include missiles, and they all have missiles hitting). And as above, the reality check on even nuclear warheads is that they need to practically (in space distance terms) hit the target directly.

 

[tater]

Ever read Mayday? It is supposed to model LBB2 combat and the later versions had conversion notes for adapting HG and HG ranges.

Take what it says with a pinch of salt, for reasons that should become readily apparent

HG short range - 5 light seconds, long range 5-15 light seconds.

4.5 million clicks weapon range

Agree, ranges for the different books are all over the map. There is no good way to make sense of all of them at the same time, you need to pick and choose.

The thread topic is about the lack of "torpedoes." On topic, and related to my stuff above about missiles, I think that missiles ARE torpedoes if they are treated the right way. For smaller ships, even in HG, also in B2, and particularly B2 with sup3, missiles are extremely deadly. Mission kill with 1 hit.

HG deals with the bigger targets, and has the arbitrary loss of critical hits at size 9 (and this is scaling with bay size, which is odd anyway).

That's really the trick with the naval engagements, HG scales really poorly WRT target size vs numbers of weapons increasing "factor." With small lasers, you definitely have a realistic idea that more hits does more hits, but cannot magically burn though a hull they cannot burn though. Cover a tank with fragile glass, and shoot it with bb guns, the glass will eventually be gone, and no amount of shooting (save over a geological time scale) will abrade the hull. Missiles are different. It's a microcosm of the "near c rocks" argument, except the velocities required to be really dangerous to a spacecraft are well within easy, tactical reach. If fighters can possibly be in the same place at the same time as the target, they could have nasty KE weapons, for example (the missile using all g-turns just to insure a skin-kill hit, no dispersal at all, with closing velocity of the fighter/target combo, plus additional missile delta v).

 

[Carlobrand]

...That is entirely addressed in the movement phase of the game, using B2, or Mayday for movement, the "to hit" only happens after intercept. Yes, that's a place for maneuver to matter, we're past that, however, we're talking about the handful that manage the task of interception (happens in all flavors of traveller space combat, they all include missiles, and they all have missiles hitting). And as above, the reality check on even nuclear warheads is that they need to practically (in space distance terms) hit the target directly.

I'm sorry, I may not have been clear. I'm not suggesting your scenario is impossible; missiles are obviously finding the target sometimes, or they wouldn't be in the game. I'm saying your scenario isn't reliable enough to count on as the sole means of attack because of the 6G problem. Unless you've clearly got better acceleration than your target (always assuming the fuel and circumstances to make the intercept in the first place), your intercept velocities are going to vary from just-enough-to-hit to way-way-fast. Having a KKV as an auxiliary is fine, but against a 6G target - a lot of warships - they often aren't going to have the chance to build up the speed to be real killers 'cause the enemy's going to be very deliberately avoiding the kind of maneuvers that will give you that chance. It doesn't matter how wide your net is spread if the target has the range and time to bring his velocity up enough to take the sting out of your attack, and he will be very likely doing just that when he sees missiles launched or a ship inbound at a dangerous speed. Your missile works best as a means of killing civilian craft who aren't going to have the power to escape.

If I recall, the missiles already have some rule that provides for extra damage if the intercept speed gets above a certain point, so some of what you're talking about is embodied in the rules, just not all of it. Can't recall where or what the details are.

 

[tater]

6g doesn't matter. Not true, it matters, but not enough.

If ships are even sort of realistic in a way we expect, the 6g thrust is out the back, right? Traveller ships have big, cool m-drives at the back, right? Else they are UFOs and can instantly go 6g in any direction. So to evade at 6 g, the ship has to be pointed at a right angle to the intercept vector for maximum deflection relative to the missile.

We will assume this is always the case, while in reality, the ship first has to rotate to that position, and this means it might have to chose which missile (or group) it will try to evade maximally. (this has some great role-playing implications, BTW, you evade vs one, and decide to shoot at the other, for example)

In 1 second, at 6g, a ship is displaced 29.4 meters. That's it. That's what 6g bought you, ~30m. If the ship is bigger than 30m, and the missile was gonna hit when it was 1 second away, it's still gonna hit. Note that for our 6g missile, that 1 second is several hundred km away at t=0 (where t=1 is impact).

If it is possible to launch missiles a few combat turns from impact in any of the systems and sometimes get hits, then kinetic kill missiles are viable, indeed likely as they are frankly a better option than nukes.

We operate under the cannon assumption, after all, that traveller navies use nuclear missiles, and they need to detonate at a few km away to be effective.

 

[rancke]

If ships are even sort of realistic in a way we expect, the 6g thrust is out the back, right? Traveller ships have big, cool m-drives at the back, right? Else they are UFOs and can instantly go 6g in any direction. So to evade at 6 g, the ship has to be pointed at a right angle to the intercept vector for maximum deflection relative to the missile.

I think it was Heinlein who said that to avoid a collision was the simplest astrogational task there was. Just alter your vector any degree, any amount, as long as it's not directly at an object coming at you bearing 0 0 0.

Once you do that, it becomes the incoming missile's problem to alter its own vector very specifically to the sole one that will intercept you now.


Hans

 

[tater]

The distance that a missile can be picked off is what I'm referring to. It has to be guided all the way to the target. I've done the calcs. The unguided perpetrators would have to be released TOO close to the maneuvering targets. It isn't viable.

So nuclear missiles never do damage in traveller? They detonate---even assuming huge warheads---at small, double digit ranges in km, at most (well under 50km). If nukes can ever do damage to a warship, missiles get within those kinds of ranges. The do loads of hits in traveller, so our KE missiles can detonate at those kinds of ranges for back of the envelope calculations. I was assuming they detonate at hundreds of km, to get a large cloud. 20km makes it like a shotgun blast in the chest.

The problem is not that they are not viable, quite the contrary, the trouble is that it is not unreasonable for a single missile to possibly critical hit a real warship.

That's a torpedo.

Traveller has BBs with hundreds of missile bays, firing huge numbers of missiles. In HG rules, this results in hull scrubbing, which is actually not unreasonable for KE missiles that use clouds of tiny penetrators. If they went for larger penetrators (or direct hits) with the same vast numbers of missiles, I'd expect many clean misses, but even one direct hit could take a capital ship out of action, or at least seriously damage it.

In ww2, incoming torpedoes meant that even the largest ship stopped what it was doing, and it "fought" the torpedo (by turning into or away from the attack to comb it). No BB skipper thought their belt armor was just fine, and ignored them.

A single fighter, say a cool design like the Gamilas Ramhead (if you watched Star Blazers/Space Battleship Yamato) comes in with a huge missile. In traveller terms, maybe a 25 ton fighter holding a 10-15 ton missile. A squadron comes in. Can they make it to the same hex as the enemy BB in any of the combat systems? They get there, then fire the missile. We will call it 6g acceleration. The missile gets a small time 6g (the distance is now small) accel added to the vector of the fighters. If they are closing fast---which would be likely since that gives the shortest time under fire by the target---the missile is only using acceleration to intercept the equally accelerating target (in a magical world it is equal, in the real world the evasion would be less than 6g orthogonally to the missile path on average).

Best defense might be a CAP to nail them before they get close... that means large traveller warships would carry fighters... oh, wait, they do Maybe fleets would want screening ships between the large ships and the enemy to mitigate missile attacks.

WW2 is not a bad model for fleet actions, really.

 

[HG_B]

So nuclear missiles never do damage in traveller? They detonate---even assuming huge warheads---at small, double digit ranges in km, at most (well under 50km).

?? Nukes (small missile carried ones in Trav) do damage. However, they would have to detonate 1-2 km from the target. An atmospheric nuk blast is totally different that one in a vacuum. (you can research it if you like). So, as I said, the missile carrying perpetrators have to get too close before they deploy. Close enough to be destroyed before they can. If they deploy at longer ranges they will most likely miss a ship that is actively maneuvering.

 

[tater]

I think it was Heinlein who said that to avoid a collision was the simplest astrogational task there was. Just alter your vector any degree, any amount, as long as it's not directly at an object coming at you bearing 0 0 0.

Once you do that, it becomes the incoming missile's problem to alter its own vector very specifically to the sole one that will intercept you now.


Hans

Not really in this case. He's talking a slower motion situation. Missing the earth, realistic spacecraft of the not too distant future, etc. A missile that can match the acceleration of the target is what we are talking about, and we are assuming that the target can magically evade at a perfect 6g (meaning it need not slew the ship to evade, that it can randomly displace sideways at 6g, instantly).

If the missile explodes into a cloud of shrapnel, the missile is not discrete any more, it is a large cloud, perhaps 10s of km across for each missile. Missiles would then be programmed to fly if the shooter wanted in a plane, with their heading roughly normal to the plane. They'd detonate and cover an area hundreds, even thousands of km wide with shrapnel.

Note that I also think that shooting missiles down is a trivial fire control issue. Inside of some fraction of a light second, in fact, it should be impossible for directed energy weapons to miss ANY target. So if you envision lasers pulsing away killing dozens of missile each in a few seconds, then when your scout ship is under fire from a similar laser, it should be hit dozens of times in a few seconds as well. Again, 6g in 1 second is 29.4 meters. Any ship bigger than that will always be hit by ANY directed energy weapon within a half a light second. 100% hits, it's impossible to miss (0.5 ls because the information you have is 0.5 seconds old, and then it takes another 0.5 seconds for the shot to arrive).

Most missiles should get shot down at some range. Biggest limitation might be multiple defense lasers shooting the same vampire.

And once again, missile in traveller either work, and KE weapons work, or they never hit at all, since nukes need to actually get closer than KE missiles to be effective.

 

[HG_B]

If the missile explodes into a cloud of shrapnel, the missile is not discrete any more, it is a large cloud, perhaps 10s of km across for each missile.

If a small missile is to create a "cloud" of shrapnel 10's of km's across, it either: 1) has to have the fragments be VERY, VERY tiny (thus not being a real threat) or, 2) be a REALLY huge missile (star ship sized).

 

[tater]

?? Nukes (small missile carried ones in Trav) do damage. However, they would have to detonate 1-2 km from the target. An atmospheric nuk blast is totally different that one in a vacuum. (you can research it if you like). So, as I said, the missile carrying perpetrators have to get too close before they deploy. Close enough to be destroyed before they can. If they deploy at longer ranges they will most likely miss a ship that is actively maneuvering.

Yeah, I said that. I slopped a 20kt to allow some radiation damage and said maybe 10km at the outside.

Why is that "far?"

Assume the relative V of the launcher and target is 0. Missile launches and 10 minutes later at 6g hits. (2/3 turn, half turn, or 1/3 turn depending on system). The missile is now going 35km/s (0.029 s/km).

It detonates at 2km away, like our nukes. That's 5 hundredths of a second. The ship will evade 0.07 meters in that time frame. How is this missing, again? A more typical closing velocity for a traveller missile would be a multiple of that, this is an example for a missile launched from 0 right on top of the target.

 

[tater]

If a small missile is to create a "cloud" of shrapnel 10's of km's across, it either: 1) has to have the fragments be VERY, VERY tiny (thus not being a real threat) or, 2) be a REALLY huge missile (star ship sized).

Sure. Or it detonates farther away, and has a less than 100% chance to hit.

You can have a 1 gram bb, but they are spaced far enough apart that there are starship-sized gaps in coverage. Roll a die

Nastier hit, many chances of a miss.

If we allow detonation at virtual contact, say 1-2km , then the cloud is 10s of METERs across. Allowing KE missile within 2km is functionally identical to a full hit by the entire missile more often than not.

A huge missile might be the size of a tiny fighter, I'm thinking.

 

[tater]

I should add that I'm simply stating the obvious, that missiles can possibly hit a target, and if they do, it's bad.

The player-level combat systems already internalize this fact. Missiles are nasty for player ships, as they should be---maybe they could be even worse, but we always played that fighting the military meant the missiles would be nukes, and that means at 2g, a close enough blast that the ship is gone (virtual contact), and many if not most will hit.

HG has always been broken in many ways, and this is one. I think for a general case, conventional missiles can be assumed to be shrapnel types, and we can assume that in general they scrub the hull. I think that all missiles, as a function of factor should have the chance to critical ships, regardless of ship size, however. That doesn't mean every single fighter launching 1 missile will critical a BB, but once the factor is 9, then there should be a chance depending on velocity (which HG doesn't deal with, so some HG with movement hybrid).

The cannon ships are actually OK, it's HG that has always broken them, anyway.

 

[HG_B]

HG has always been broken in many ways, and this is one. I think for a general case, conventional missiles can be assumed to be shrapnel types

Only in a fantasy game. That scenario holds no water.

 

[tater]

A 0.5m by 2m section of a larger missile is the warhead. This could contain about 40,000 bbs 0.5cm diameter. Those are about 0.6 grams if tungsten. More if they are traveller matter (SD/BSD, whatever).

Dispense them by spinning the missile, then it opens a hole, and they fly out. It's a simple engineering problem to make them disperse in a pretty predictable way such that they are roughly spaced every XX meters apart. Doesn't need to be perfect, we have to-hit rolls

At 35km/s, our case of the missile with no relative velocity shot in the same hex or so, each does about 0.37 MJ. Hull scrubber at best. At a not atypical 350km/s, that goes to 36.75 MJ. That is for each 0.5cm diameter ball.

If the missile can get within, heck, 100 km, many of those will hit if the missile at the time of detonation is on a good intercept (we can assume many won't be to make the to-hit less nasty). If they disperse at 2-10km, where a nuke makes it to, they only need to spread these 40k balls over a few meters, and most all will hit. Doesn't take much closing velocity for this to start looking fatal.

 

[tater]

Only in a fantasy game. That scenario holds no water.

No.

It's fantasy for nukes to be the dangerous missiles. I was trying to make KE missiles LESS nasty by letting nukes detonate at 10km. You want 1-2km. If a missile can make it to 10km, KE missiles are deadly. If they can make it to 1-2km, they are not only very deadly, it starts looking like a problem to solve, since missiles are not the nasty weapons spinal mounts are in traveller.

I showed my work, even back of the envelope. Correct my math. Assume your 2km detonation distance for a nuke, and show how a cloud of shrapnel moving at 35 to 350km/s can miss a 6g evading target given different cross sections of shrapnel when it detonates at 2km. The target displaces by 7 cm in that time period.

 

[tater]

How about testing combat systems with a special case.

Battleship is hit by a spinal. M-drive disabled critical.

Target is now not evading at all. It's drifting towards the enemy at a few hexes a turn in whatever system. 150km/s, say (very slow in traveller).

What happens if I shoot missiles at it? Nukes, doesn't matter. Nukes will have contact detonation if they survive defensive fire/dampers. Ship should die if hit. Conventional missiles? Ditto. 150+ whatever time the missile have to get their velocity up. Every missile surviving defensive fire will certainly hit. Any single hit might kill the battleship. In HG, more scrubbing at best.

How is this not true?

A same-hex launch, 35km/s, 50kg missile fired to hit directly. 30,625 MJ. That's 0.03 TJ. A 20kt nuke is about 80TJ. So our tiny, single missile is not enough at that low speed. At 200km/s (drifting speed above, plus a hair more from the missile? 1 TJ. A very tiny nuke, but all this energy to the target, not isotropically radiated like a nuke will be (half the blast to space, even on contact). Still a huge amount of damage. Maybe not a kill, however. Dunno what we should expect our huge warships to absorb. a terajoule is a lot, though. This goes up with the square of the closing velocity, though, so a missile that can do 6gs for a couple turns, launched by a ship moving towards target at a few hundred km/s, and a target drifting towards enemy at the same means that this rapidly becomes fatal.

BTW, the cutoff for a 50kg missile to have KE equal to a Trinity test sized nuclear bomb is 1788km/s.

Mayday has a scale of 300,000km per hex, and 100 minutes. A speed of 1 means a KE missile has 2x the energy of a 20kt bomb.

BL uses 30,000km, and 30 minutes, so a speed of 2 is over 20kt KE for a 50kg missile.

It will all be similar in the various flavors of traveller space combat. An incredibly low speed = huge energies. The energy obviously goes as the square of the closing velocity, and linearly with mass, so tiny bbs, that are 1/1000th the mass will be that much less energy. The energies are large enough that this doesn't matter.

 

[aramis]

Not really in this case. He's talking a slower motion situation. Missing the earth, realistic spacecraft of the not too distant future, etc. A missile that can match the acceleration of the target is what we are talking about, and we are assuming that the target can magically evade at a perfect 6g (meaning it need not slew the ship to evade, that it can randomly displace sideways at 6g, instantly).

If the missile explodes into a cloud of shrapnel, the missile is not discrete any more, it is a large cloud, perhaps 10s of km across for each missile. Missiles would then be programmed to fly if the shooter wanted in a plane, with their heading roughly normal to the plane. They'd detonate and cover an area hundreds, even thousands of km wide with shrapnel.

Note that I also think that shooting missiles down is a trivial fire control issue. Inside of some fraction of a light second, in fact, it should be impossible for directed energy weapons to miss ANY target. So if you envision lasers pulsing away killing dozens of missile each in a few seconds, then when your scout ship is under fire from a similar laser, it should be hit dozens of times in a few seconds as well. Again, 6g in 1 second is 29.4 meters. Any ship bigger than that will always be hit by ANY directed energy weapon within a half a light second. 100% hits, it's impossible to miss (0.5 ls because the information you have is 0.5 seconds old, and then it takes another 0.5 seconds for the shot to arrive).

Most missiles should get shot down at some range. Biggest limitation might be multiple defense lasers shooting the same vampire.

And once again, missile in traveller either work, and KE weapons work, or they never hit at all, since nukes need to actually get closer than KE missiles to be effective.

Assuming the 10cm missiles of SS3, the Traveller G of 10m/s/s and 0 pointing time, the assured hit on accurate pointing of a laser vs a missile in head on is a function of beam diameter and the missile's off-axis acceleration (which, we can assume, is about 25%, due to vectoring of the nozzles.

given a half meter diameter beam, and 0 pointing time, and 25% off-axis thrust...
D_LS=0.5√(R/(AF))
D_LS=0.5√(0.25/(60*0.25))
D_LS=0.5√(0.25/(15))
D_LS=0.5√(0.01666)
D_LS=0.5(0.12909944487358055)
D_LS=0.06454972243679027

So about 19364 km. Each laser should hit a missle 100% of the time at just shy of 20 km. WHich is why TNE switched to Detlasers.