Lasers

[Major B]

I have a question regarding how lasers are treated in High Guard.

I know, this is the MT forum - but I need to clear this one up before I can get after some problems with lasers in MT.

So, from my dim memories of playing CT I thought that beam lasers could be used for antimissile defense but pulse lasers could not. However, I just noticed in HG (on page 45) that "Beam weapons include lasers and energy (fusion and plasma) guns."

This text is located next to the "Attacking Beam Factor" table but above that is a table for missiles penetrating "Sand or Beam." Does this mean that pulse lasers can also be used for missile defense?

 

[far-trader]

Yep, no prohibition on using pulse lasers in an anti-missile role. They are a little less effective than beam lasers being -1 to hit in CT B2 (actually in the Starter Traveller book) and a step down on the USP code in B5, but doing more damage (inconsequential in the anti-missile role but a decision point in the offensive role).

 

[aramis]

Yep.

 

[Major B]

Okay, thanks for that even if it makes the disparity between treatments in MT even worse than I had thought.

The laser weapon tables on page 73 of the Referees Manual looks like a direct lift from High Guard except that TL16 improved versions are added.

The dynamic is the same as CT:
- pulse lasers are less effective than beam lasers (up to half)
- pulse lasers use the same amount of power and weigh the same as beam lasers
- pulse lasers cost half as much as beam lasers

But, the dynamic shown on page 78 for vehicle mounted lasers is very different:
- pulse lasers penetrate better and cause the same damage as beam lasers
- pulse lasers require twice the power of beam lasers but still weigh the same
- pulse lasers cost slightly more than beam lasers

Is this because the vehicle tables on page 78 are drawn from Striker while the table on page 73 is drawn from CT Bk 2 and HG?

 

[Omnivore]

For the most part this is another area (like computers) where technology has moved well past Traveller assumptions. For the two most likely mid-future weaponized laser types (free electron or semiconductor), continuous wave (beam) or pulse mode is, for the most part, an operational choice. Most likely, going by current theory and practice, a weaponized laser would fire a train of pulses - neither a Traveller beam or pulse laser but a mixture of both.

It is also likely that a single laser cavity would be used for multiple targeting mirrors (turrets) through the use of beam splitters. Fire Fusion and Steel has the best handling of lasers though it lacks the separation of targeting mirrors from lasing cavity.

Traveller also made some rather optimistic assumptions about laser ranges and in FF&S the authors had to resort to using 'gravitic lensing' to make physics match those expectations.

Unfortunately this is a topic just like power plant fuel which is corrected in one version only to be broken anew in the next

 

[Major B]

Omnivore, I don't disagree but your point sort of distracts from my question.

Your point is that the treatment of lasers in traveller does not well reflect reality as we understand it today. Probably true but not really as important to me.

I would like to see the treatment be as close to reality as possible, but it is more important to me that the treatment is internally consistent in the game.

Looking at starship lasers, pulse weapons are less effective than beam weapons.

Looking at vehicle lasers, pulse weapons are more effective than beam weapons.

I'd like to know if there is something I'm not considering that addresses the inconsistency or if there is one that is "more right" than the other. If the latter can be established then maybe I can draft some errata or a house rule to address the inconsistency.

 

[Omnivore]

Sorry Major B, what I was implying was, you are correct that they are inconsistent.

One solution is to simply say that it is a matter of scale, the larger starship beam lasers become much more powerful while the starship sized pulse lasers don't scale as well. Only problem would then be if you tried to use Striker to design a custom laser of near or superior power to starship lasers.

Another might be to say that vehicle and starship lasers are fundamentally different, with the starship lasers the extreme range requirements result in a different design - basically saying something like Striker lasers are gas/chemical and MT starship lasers are free electron lasers.

Hope that helps and sorry for injecting confusion

 

[travlar]

Well, it's not quite so simple as pulse lasers being worse on starships; they have an extra +2 on the damage table, IIRC. The lesser accuracy may not be worth it, though.

 

[Major B]

One solution is to simply say that it is a matter of scale, the larger starship beam lasers become much more powerful while the starship sized pulse lasers don't scale as well. Only problem would then be if you tried to use Striker to design a custom laser of near or superior power to starship lasers.

Another might be to say that vehicle and starship lasers are fundamentally different, with the starship lasers the extreme range requirements result in a different design - basically saying something like Striker lasers are gas/chemical and MT starship lasers are free electron lasers.

Hope that helps and sorry for injecting confusion

No apology needed. Your first point regarding scale may be the answer.
I checked in the Striker laser design sequence (Bk 3 pg 18-19) and found that (volume = weight = (power * .066)).

This means that the beam lasers in the MT RM on page 78 are clearly lifted from Striker.

However, the same rule cannot be applied to the starship lasers as the volume of a 250 Mw laser would be 16.5 kl. It will be hard to get three of these weapons into a turret that only fits 13.5 kl.

But, if for beam lasers at least, the weight = volume rule remains in effect then we can extrapolate from the starship weapons table that a TL 7 or 8 (more confusion) laser weighs 5 tons and displaces 5.0 kl. This is still too big to fit three into a 13.5 kl turret but much closer than 16.5

So, maybe the volume of the laser weapon stays consistent up to around 50-100 Mw and then benefits from a scale adjustment so that the 250 Mw model is only 5.0 kl?

I guess what I am saying is that I find the scale argument more plausible than the argument that the lasers are of fundamentally different types. More to follow on the pulse laser differences after I have reread more of Striker.

 

[Major B]

Point taken Travlar. I was simplifying to make a point but probably over simplified.

But this point illustrates another disconnect - the vehicle lasers all inflict the same damage though pulse lasers have better penetration.

For starship lasers, pulse lasers penetrate defenses less effectively (because it takes more weapons to attain an attack factor) but inflict more damage if they hit.

Is this because the pulse laser can better penetrate the starship's armor (as opposed to penetrating the starship's defenses - a different concept).

 

[far-trader]

For starship lasers, pulse lasers penetrate defenses less effectively (because it takes more weapons to attain an attack factor) but inflict more damage if they hit.

Is this because the pulse laser can better penetrate the starship's armor (as opposed to penetrating the starship's defenses - a different concept).

That's the way I've seen it. Basically (CT/HG) comparing:

Pulse Lasers operate at a higher power by charging the capacitors longer between each shot. This results in a higher damage (armour penetration) when the shot or shots hit. However there are fewer shots fired to cover the same attack so the chance of hitting are reduced.

Beam Lasers operate at a lower power by charging the capacitors for a shorter time between each shot. This results in lower damage (armour penetration) when the shot or shots hit. However there are more shots fired to cover the same attack so the chance of hitting is improved.

Both lasers operate by cycling discreet shots over the combat turn. A Beam Laser is not a continuous beam. And a Pulse Laser is not a single shot. How many cycles? I leave that vague to protect the innocent They both draw the same power, they just apply it differently.

The cost difference is something I've long disagreed with and house ruled as reversed.

In MTU:

Beam Lasers are less expensive, less robust, they don't have the higher rated capacitors. Beam Lasers are generally civilian and defensive weapons ideally suited to marginally trained gunners, low computer ratings and anti-missile fire. (The lack of gunner expertise and beneficial computer programs do not impact the role)

Pulse Lasers are more expensive, built more robustly, with higher rated capacitors. Pulse Lasers are generally military and attack weapons better suited to well trained gunners, higher computer ratings, and targeted fire. (The availability of expert gunners and computer bonuses offset the negatives and bring the extra damage to bear in combat)

...curiously, since I have also long had Missile and Sand launchers blended into one weapon platform (a Launcher, capable of firing both), it never occured to me to treat Lasers similarily and just have the cycle rate variable. I think I'll have to adopt that now as well

In MTU a simple Sand launcher is as listed, MCr0.25 and is only good for Sand. And the basic Missile launcher is as listed as well, MCr0.75 and only suited to Missiles. The option for a multirole Launcher is there that handles both for MCr1.0...

...I think to adopt the Lasers to it (and clutter up the Major's thread with my thinking out loud ) I'd have to make the Multirole Laser MCr1.0 (capable of either pulsed or beam fire), the Pulse Laser MCr0.75 and the Beam Laser MCr0.5 (though prices flipped for canon use)

If any of that is useful to you Major B it is entirely an accident

 

[Magnus von Thornwood]

Beam v. Pulse, Vehicle v. Starship.

Perhaps the Vehicle Pulse Laser is better for ground combat as it is not as susceptible to thermal blooming. Whereas in space and no atmo Starship Beams do better since they don't have to fight the atmo.

But then I see Beams as a continuous beam that can be kept on the target and Pulse Lasers use a pepper box technique, lots of little rounds and hope one hits.

Also, Far-Trader, very nice work up there. Till your little write up, the difference never made much since to me. Now it does, sort of, mostly.

 

[aramis]

There is a small bit of physics involved, MajorB...

Vehicular lasers pulse becomes more effective because the beam hits the same spot each pulse (or near enough as makes no difference), so the residuum of the material vaporized by a solid beam has no chance to dissipate, becoming a self-generated smoke screen against the laser. Pulse Lasers allow it to vacate the hit spot so that more beam energy goes in to the damaged area of armor.

Space craft ranges are such that you're just trying to hit the target at all, and have little to no ability to actually dictate where on the ship the hits will land. Plus, with vacuum, the residuum (being a gas) is sucked out almost immediately anyway, and the pulse interruptions mean the next pulse hits fresh armor.

 

[McPerth]

Well, it's not quite so simple as pulse lasers being worse on starships; they have an extra +2 on the damage table, IIRC. The lesser accuracy may not be worth it, though.

This may well depend on situation...

If you have a trader (or a fighter) with power just enough for one weapon, you'd better install a pulse laser, as the factor will be the same (1-3, depending on TL), they cost only half the price, and yet you'll do more damage with it.

Same can be said if you can rely on your computer (or gunner) offsetting the lower modifiers in the table. With small batteries, modifiers may be low enough as for a good gunner being better than them to use as DM, so the price and damage matters take precedence again...

Of course, if your main use is anti-missile, you'd better install beam lasers, as they give you better protection.

 

[Major B]

Thanks to everyone for the responses and information. I'm still reading up on the pulse lasers material in Striker but the material for beam lasers is relatively straightforward. The data for the TL8 beam lasers listed on page 78 (Step 25, Beam Laser Guns) of the Referees manual was derived almost directly from Striker so I am going to expand on them and then see if the analysis can be ported to TL13 weapons. After that, TL16 but lets not got ahead of ourselves. Here are the formulas I could identify:

Volume <m3> = input power <Mw> * 0.066
(matches Striker exactly)

Weight <tons> = volume <m3>
(matches Striker exactly)

Price <Cr> = input power <Mw> * 4,000
(closely matches but omits the fire control cost required in Striker)

Maximum Range = (input power <Mw> / 4) * 20 km
(matches Striker’s calculation for extreme range)

Penetration = (input power <Mw> / 4) * 10 then crosscheck on armor table
(matches Striker’s derived value for penetration at effective range – note that effective range is 1/10th of the listed maximum range)

Attenuation = It appears that the value for attenuation should have been derived from cross-referencing weapon effective range (see note above) with the range bands described on pages 67 and 74 of the Player’s Handbook. This is because the penetration calculation in Striker applies out to the effective range of the weapon while penetration at further ranges is reduced. However, using this method returns different values for attenuation as shown on the table below. I do not know if lasers were intentionally made less effective in MT of if the attenuation was simply miscalculated.

Damage = variable: at 5 Mw and higher damage = (input power <Mw> * 2)
(no relation to Striker). If this formula had been continued below 5 Mw, the damage for a 1 Mw laser would be 2 (rather than 5) and for a .5 Mw laser it would only be 1 (rather than 4).

Danger Space, Signature, ROF values all appear to be derived for MT without any relation to Striker though if I missed or forgot something please let me know. Striker does have signature rules but they don’t appear to relate to MT.

So, the below table corrects the erroneous attenuations published in the RM. Note that only TL 8 Beam Lasers are shown for now:

[FONT=Courier New]TL 8 Beam Lasers:[/FONT]
[B][FONT=Courier New][SIZE=1]Input                         Pen/       Maximum            Auto   Danger[/SIZE][/FONT][/B]
[SIZE=1][FONT=Courier New][B][U]TL[/U][/B][B] [U]Power[/U]  [U]Volume[/U] [U]Weight[/U]   [U]Price[/U]  [U]Attn[/U]  [U]Dam[/U]  [U]Range[/U]             [U]Targets[/U] [U]Space[/U]  [U]Sig[/U] [U]ROF[/U][/B][/FONT][/SIZE]
[FONT=Courier New][SIZE=1]8    0.5   0.033  0.033   2,000   5/[COLOR=#c00000]3[/COLOR]    [COLOR=#c00000]1[/COLOR]  Distant (2.5)        2      1.5   H   40[/SIZE][/FONT]
[FONT=Courier New][SIZE=1]8    1.0   0.066  0.066   4,000  10/[COLOR=#c00000]4[/COLOR]    [COLOR=#c00000]2[/COLOR]  Distant (5.0)        2      3     H   40[/SIZE][/FONT]
[FONT=Courier New][SIZE=1]8    5.0   0.330  0.330  20,000  28/[COLOR=#c00000]4[/COLOR]   10  Very Distant (25)    2      4.5   H   40[/SIZE][/FONT]
[FONT=Courier New][SIZE=1]8   10.0   0.660  0.660  40,000  36/[COLOR=#c00000]5[/COLOR]   20  Very Distant (50)    2     15     H   40[/SIZE][/FONT]
[FONT=Courier New][SIZE=1]8   25.0   1.650  1.650 100,000  47/[COLOR=#c00000]5[/COLOR]   50  Regional (125)       2     30     H   40[/SIZE][/FONT]
[FONT=Courier New][SIZE=1]8   50.0   3.300  3.300 200,000  55/[COLOR=#c00000]5[/COLOR]  100  Regional (250)       2     45     H   40[/SIZE][/FONT]
 
[FONT=Courier New]Entries in black match entries in the RM page 78 (Step 25, Beam Laser Guns)[/FONT]
[FONT=Courier New]as modified by [/FONT][FONT=Courier New]current errata. [/FONT][FONT=Courier New][SIZE=1][COLOR=#c00000][SIZE=2]Entries in red are corrections.[/SIZE] [/COLOR][/SIZE][/FONT]

So, should the modified damage and attenuation values shown above be considered errata? Let me know your thoughts before I move on to the next step.

 

[McPerth]

About the fact of beam lasers being more accurate (higher battery rated), while pulse lasers more lethal (+2 to damage or better penetration), I've always thought that's because the same power (at least in starship combat), in beam lasers, is applied on a continuous basis (as a laser pointer could), so being easier to aim, but in pulse lasers were applied in short pulses, so each pulse releasing more energy (same Mw, less time, that implies more Joules released), being somewhat explosive, while beams would be more 'abrasive', so to say.

Off course that's only my thought, not canon, and I'm not an expert in physics...

 

[Strummist]

That's definitely true for real-world lasers - you get more "bang for your buck" with a pulse than a continual-mode laser. The biggest lasers right now are at Livermore's NIF and LIFE project, and they are pulse.

In fact the greatest monetary damage per second by any science experiment was when a femtosecond laser destroyed the target material.

 

[Major B]

Off course that's only my thought, not canon, and I'm not an expert in physics...

It makes good sense to me - but I'm a historian.

That's definitely true for real-world lasers - you get more "bang for your buck" with a pulse than a continual-mode laser.

Okay, one more thought filed in the "how they work" file.

Thanks for the additional information, both of you. Any thoughts on the changes to attenuation and damage I posted above?

 

[McPerth]

Any thoughts on the changes to attenuation and damage I posted above?

In principle, it seems logical that the damage/penetration are directly proportional to the energy imput. After all, the way to do damage uses to be a matter of transmiting energy (either kinetic, heat, radiation or whatever) to the target in enough quantity as to damage it.

Noneless, I guess to take this theory to practice may not be so directly proportional. I don't know if the eficiency for weapons increases, decreases or stays from lower power weapons to higher power ones. The main explanation for those lower power weapons to have higher values than predicted by the equation (as you pointed there were) would be to assume than lower power weapons lose less energy in heat and other losses (and so are more efficient), and I don't know if this is true.

Also to note is that penetrating power and damaging power are not always directly proportional, many times (at least in kinetic damaging missiles) are inversely proportional. I guess you'll know better than myself in this field, as I understand you are in the military, but most good penetration bullets are less damaging than those with less penetration power (e.g. a shotgun blast may be devasting to an unarmored person, but if the same person wears armor, a solid shoot will be better. Same happens, AFAIK, to lead bullets vs armored bullets, the former producing more damage to unarmored targets, but the latter being more able to penetrate armor). this puts a bit of strain to AHL (and AFAIK striker rules are similar, I had never opportunity to read them ) combat system, when all of it are featured on a single factor.

How will this translate (or even if it will) to non kinetic beam weapons, I don't know, but I guess the penetrating and damaging power will be more correlated on them than on kinetic bullets.

About attenuation, I guess for lasers it would be more atmosphere depedent than weapon itself dependent. I remember to have read an article on a Challenge or Digest about penetration attenuation in different atmospheric conditions (from vaccum to heavy dense atmospheres), but I'm afraid I cannot give you exact reference here.

 

[aramis]

Penetration (in mm of steel) is a function of energy denisty (j/cm^2), but it's logarithmic, not linear.