Laser changes and the tactical use of missles

[BP]

The simple formula for Kinetic Energy is mass times velocity squared. The thrust rating of a ship really doesn't equate to the danger - it is the difference in velocity. High rated M-Drives aren't really faster - only capable for getting up to 'speed' faster. A ship traveling at 6G, but for only one hour has the same 'speed' as a 1G ship traveling in the same direction for 6 hours...

Also, when talking velocity ('speed' in a certain direction) - the ship (accelerating or not) will be heading away from an impact as often as it is heading towards it.

Interstellar 'dust' generally only presents a problem of abrasion (unless delta-v is a good fraction of the speed of light) - larger particles, however can do serious damage. However, anything big and fast enough to do catastrophic damage would likely be detected and avoided.

Several modern probes have, in fact, been damaged by interstellar particles (excluding the obvious ones chasing and slamming into comets!) - so even though notable collisions are rare, they do happen. Today's probes are generally fairly fragile, but still, scale that up to a 3I TU and they are bound to happen.

For my poor players - they were 'inflicted' with such impacts on maybe 1 in 30 actual trips (which is statistically probably way too high) - and no one died or was even struck, and generally only one system was affected (damaged, not destroyed). The biggest real risk was slow loss of atmo, which was easily fixed with sprays and patches. But, it was a great excuse for alarms and panic and did slow them down on occasions.

Overall, Sophont space junk in orbits and strewn through systems would be a much greater cause for concern.

 

[vitalis6969]

It seems to me that if you are getting many pulses per second from a pulse laser then the practical effect is very little different from a beam laser, so there should be no game difference between the two.

But not all of those pulses are hitting, you are sending them at an area, hoping to increase your chance of hitting by increasing the amount of laser bursts in a given area. Just like shooting skeet.

Harder to hit? How so? Think of beam lasers as water hoses and pulse lasers as thrown water balloons. It is much easier to hit with the hose, you can sweep it across the target. But a big honking balloon will get the target much wetter all at once - if you hit in the first place.

Because it isn't a water hose, it is a laser. The shot is what? A second or two continuous beam shot? Moving at the speed of light, trying to intersect a target that is moving in a three dimensional field while you are moving in a three dimensional field. If that continuous beam hits it will deliver all of its energy onto the target. If it hits.

Lets take shooting clay pigeons here. A cloud of fine shot is used because it saturates the area and increases your chance to hit. On the downside that cloud of fine shot causes less damage and might not break the clay pigeon.

On the other hand, a slug will completely devastate the clay pigeon. But is much much harder to strike with, it is all or nothing.

The difference here is you are seeing lasers like slicer beams from B5, I do not.

 

[hdan]

The simple formula for Kinetic Energy is mass times velocity squared. The thrust rating of a ship really doesn't equate to the danger - it is the difference in velocity. High rated M-Drives aren't really faster - only capable for getting up to 'speed' faster. A ship traveling at 6G, but for only one hour has the same 'speed' as a 1G ship traveling in the same direction for 6 hours...

Right, which I why I refer to the 100d limit, which is generally the end point of an m-drive trip in MTU. Given the fixed distance the ships will be going, the acceleration used does imply velocity.

(IMTU, emergence from jump preserves your velocity relative to the gravity well you're precipitating near, so a ship that burns for 10 turns at 6G out to the jump point will need to spend at least 10 turns slowing down before they slam into the planet or fly out into space. The safest bet is to come to "zero-V" before jump. If players are feeling lucky, they can shave some time off their trip by carefully planning their ejection vectors and trying to precipitate "inbound", but I make that a more difficult check.)

Interstellar 'dust' generally only presents a problem of abrasion (unless delta-v is a good fraction of the speed of light) - larger particles, however can do serious damage. However, anything big and fast enough to do catastrophic damage would likely be detected and avoided.

I assume a certain level of self-sealing hull in addition to the subtle deflecting effect of the gravity field. Annual maintenance probably includes replacing exterior panels that have taken too many hits, etc.

In short, I don't really worry about it in a real game, but I like to have some answers handy in case players get uncharacteristically curious about these things.

 

[BP]

Using HGs corrections (Pulse = 2d6 with -2DM and Beams 1d6)...

Assume MGT was not referring to RW high power pulse lasers operating in pico- to femto-second time scales - that is trillion-ths (millionth of a millionth) and quadrillion-ths of a second - but more rather the commercial hundredths of a second type

This would account for the -2 to hit DM.

The pulsing is both a power efficiency thing (average CW power builds up and is released in a finite time - like a stored up punch) and a penetration via ablation advantage (material is quickly 'evaporated' away - leaving less material to act as a heat sink, which would spread the thermal energy away from the point of impact).

This would account for the double damage (2d6 vs. 1d6).

The higher TL change of Beam to TL 9 instead of 7 could refer to the added technical difficulties of CW lasers (thermal issues) that in the RW have lead to pulse lasers as a cost effective means of small, powerful research lasers...

 

[BP]

The simple formula for Kinetic Energy is mass times velocity squared. The thrust rating of a ship really doesn't equate to the danger - it is the difference in velocity. High rated M-Drives aren't really faster - only capable for getting up to 'speed' faster. A ship traveling at 6G, but for only one hour has the same 'speed' as a 1G ship traveling in the same direction for 6 hours...

Right, which I why I refer to the 100d limit, which is generally the end point of an m-drive trip in MTU. Given the fixed distance the ships will be going, the acceleration used does imply velocity.

Sorry - that post was in reference to far-trader's mention of 'built in correlation for a stronger field tied to faster drives', as your's did not specifically mention that characteristic.

Statistically, within 100D the litter bug who jumped before you is gonna be the biggest threat

 

[hdan]

Statistically, within 100D the litter bug who jumped before you is gonna be the biggest threat

LOL - I suspect the more respectable systems take a very dim view of dumping trash inbound, though I guess it could be legal to dump trash at the 1/2 way point if your vector was enough for escape velocity....

Hmmm, starting to get some ideas for scenarios involving space patrol and illegal "dumping"...

 

[srogerscat]

hdan's idea of the gravitic drive fied bing a low level repulsor is elegant. I love it

Vitalis6969 writes:

[Because it isn't a water hose, it is a laser.]

But they are both streams of energy directed at a target, so I think the analogy holds.

[The shot is what? A second or two continuous beam shot? Moving at the speed of light, trying to intersect a target that is moving in a three dimensional field while you are moving in a three dimensional field. If that continuous beam hits it will deliver all of its energy onto the target. If it hits. ]

But not all the one or two second beam hits the same spot on the target, it is diffused into a shallow burn that could be several meters long. A micro or cento second pulse will deliver the energy to the same spot at the same time. Well, Ok it will be spread over several centimeters, but it is still far more concentrated than the beam. And when even an unarmored ship is still quite sturdy indeed, concentration of force is vital for significant damage.

I am enjoying the hell out of this argument, by the way. By no means do I hold you in ill-regard for disagreeing with me.

 

[hdan]

Assume MGT was not referring to RW high power pulse lasers operating in pico- to femto-second time scales - that is trillion-ths (millionth of a millionth) and quadrillion-ths of a second - but more rather the commercial hundredths of a second type

Somehow I get the feeling that CT was referring to lasers that go "pew! pew! pew!" vs. lasers that go "bleeeeem!".

 

[srogerscat]

hdan writes:

[Somehow I get the feeling that CT was referring to lasers that go "pew! pew! pew!" vs. lasers that go "bleeeeem!]

Yes. Absolutely Beam lasers that fired for a few seconds, and pulse lasers that fired one fractional-second *very* energetic pulse every few seconds was the consensus view back in the day. Well, for the gamers I played with, anyway. Anybody else who played back in the early eighties who remembers different, feel free to correct me..[/quote]

 

[rust]

Absolutely Beam lasers that fired for a few seconds, and pulse lasers that fired one fractional-second *very* energetic pulse every few seconds was the consensus view back in the day.

In our case the beam laser was seen as a kind of comparatively weak
laser "searchlight" that was active for most of a combat round, while the
much more powerful pulse laser fired only once per combat round be-
cause the power plant needed a combat round to refill the capacitors.

 

[vitalis6969]

First, yes, I am enjoying this discussion and am in no way taking it as a coherent beam peeing contest... :wink:

I understand what is being said now with the beam "searchlight" vs. the energy pulse.

I wasn't seeing it in that way at all. Here is how I've been looking at it.

Let's say for example a laser dumps 1 KW ( I know, I know, small but it is just for an example) of energy into a beam laser during a combat round. You fire this beam, it has a standard chance to hit, and does X damage based on the 1 KW beam.

Now let's take the pulse laser, it also fires 1 KW worth of energy, but it is split into 10 100 watt pulses. The ten pulses fire in rapid succession, like an automatic weapon. My chance to hit is increased do to 10 "projectiles" but each one is smaller and not all will hit, thus the damage is decreased over the beam laser.

-V

 

[far-trader]

Well, just to confuse the issue a little more how's this model of how I've generally seen it grab the debate participants...

A beam laser targets the enemy maneuver box (let's make it 10x10 units, so 100 discrete possible areas for the ship to be) by crossing the lines of the grid in the box. This takes the whole turn and the whole power of the beam is spread over that area. So the comparative potential to hit is high but the damage is low.

A pulse laser targets the same enemy maneuver box by firing discrete pulses along each grid line. This also takes the whole turn and uses the same energy but areas are either off or on. So the comparative potential to hit is low but the damage is high.

That said I always felt the two were backwards as regards cost and TL.

The beam laser should be the lower tech (steady lower power), lower cost, primarily civilian defensive weapon.

And the pulse laser should be the higher tech (higher rapid power cycling), higher cost, primarily military offensive weapon.

Why?

Well the military can generally offset the reduced chance to hit with better (pricier) electronics and trained crew, as well as mounting more. The military also wants the better punch. And they can and will mount armour and other defenses so they don't need to have point defense lasers.

While the civilians want the best chance to hit with their limited mounts, electronics, and crew skill. They don't need the bigger hit to kill missiles, any hit will kill a missile, and they need to kill missiles because they won't have the luxury of armour and other defenses.

...but I do like the thinking vitalis has offered, interesting points to consider.

 

[BP]

...
Hmmm, starting to get some ideas for scenarios involving space patrol and illegal "dumping"...

Exactly!

Of course, with the nature of jump being how it is - thumbing one's 'trash' at the locals on the way out is very 'real' possibility (not to say that it wouldn't catch up to them eventually - but that doesn't stop people from doing the same in RL).

Certainly something fun to 'throw' at one's players!

Slinking away to the bad pun corner now...

 

[DFW]

I do await being shown the rules as you probably know MGT better than I.

I would take the other approach. Since fast micrometeorites would change
the situation in the Traveller universe significantly if they would exist, and
since they are mentioned nowhere in the rules, they quite obviously do not
exist in the Traveller universe. :wink:

Only problem is they have been mentioned in past edition AND accounted for.
Not only that, ya can't get rid of them without getting rid of planets.

 

[DFW]

And close to my own ancient rationalization. Since Traveller ships don't fear micrometeor strikes (the rules never mention it, probably an oversight, but we're stuck with it) they must not be a threat.

Quite incorrect. MT covered the subject well.

 

[rust]

Not only that, ya can't get rid of them without getting rid of planets.

Ah, this is Traveller - Grandfather has designed a sixdimensional device
that collects all particles up to a certain size from the entire galaxy and
transports them to a pocket universe where they are used to create a
series of nebula sized statues of Grandmother as her birthday present.

 

[far-trader]

And close to my own ancient rationalization. Since Traveller ships don't fear micrometeor strikes (the rules never mention it, probably an oversight, but we're stuck with it) they must not be a threat.

Quite incorrect. MT covered the subject well.

While I was more thinking CT (and MGT though my sources there are few) apparently I've forgotten or missed some MT info then, quite possible for any number of reasons. Can you narrow down the area for my curiosity?

 

[DFW]

Can you narrow down the area for my curiosity?

Sure. Pg. 63 - Ref Manual, "Spacecraft and starships require a minimum armor value of 40 for protection against micro-meteoroids and radiation."

 

[far-trader]

Can you narrow down the area for my curiosity?

Sure. Pg. 63 - Ref Manual, "Spacecraft and starships require a minimum armor value of 40 for protection against micro-meteoroids and radiation."

Thanks DFW

Right, I'd forgotten that entirely. A bit off topic but, the reason being that it is not really armour but the minimum shell required for ships, aka no armour in CT. And I'm sure your own calculations of impact velocities would show that MT armour 40 is not sufficient of itself. There must still be something else at play to avoid the threats. As noted maybe ships don't operate at high velocities, the danger is accepted, or some other shielding is involved, especially in respect to skimming fuel from a gas giant where armour really isn't going to help a lot, especially that little.

 

[rust]

Sure. Pg. 63 - Ref Manual, "Spacecraft and starships require a minimum armor value of 40 for protection against micro-meteoroids and radiation."

According to the Demolitions Table on Page 103 of the same supplement
just 6 kilogram of conventional explosive of TL 9 are sufficient to pene-
trate Armour Value 40 enough to break its sealed environment integrity.
If the energy of 6 kg of explosive are enough to penetrate the armour,
its protection against the kinetic energy of micro-meteoroids is truly ne-
gligible.