[Ultratech, TL 10] Commando vs. Heavy Battlesuit, also Beam Weapons vs. Guns

[Joel]

1. Is it just me or does the Heavy Battlesuit seem absurdly weak compared to the much lighter Commando Battlesuit?

The heavy battlesuit weighs 3 times as much, but has only +5 more ST, less than 50% more DR, half the PF (10 for commando, 5 for heavy), and half the pressure support (20 for commando, 5 for heavy). Where is all that extra weight going if not strength & armour? The TL 10 fusion reactor is only 80 pounds heavier than the E cell the commando battlesuit uses, so where are those other 250 pounds going? I'd have expected it to have at least 2x the DR & strength.

I'm thinking about changing it to 200/150 DR, +25 Strength, and equal PF & Pressure Support.

2. I've also been a bit annoyed at the difficulty in getting any reasonable beam weapons in the ST 25+ range using the rules in Pyramid 3/37. They all seem kind of crap compared to guns in the same weight class. I know this is due to cube root scaling for damage vs. energy for beams, so my question is really the reason for this scaling. Why are larger beam weapons so incredibly energy in-efficient compared to projectile weapons?

[David Johnston2]

You need to read the write-ups. The Heavy has a bunch of frills the Commando doesn't including an ESM suite, hardened armour and a weeks worth of food. And then there's stereo.

[Joel]

The commando battlesuit does have tactical ESM, and it's only 2 lb anyway.

Given that the things the heavy battlesuit has that the commando doesn't (except a little bit of DR and ST) are:

trauma maintenance (neg. weight)

a provisions dispenser (p. 187) with a week’s provisions (4.5 lb)

36 hours extra air (10 lbs)

reactor instead of E-cell (80 lbs, at most [it doesn't say fusion reactor, but it works alot like one and 100 lb fusion reactors are available at the TL])

electromagnetic armor (unknown weight)

that must be some heavy electromagnetic armor.

I just see very little reason a military would spend all that extra money, the only real meaningful advantage is the reactor (it's a big one though). The heavy armors just seem kind of understated.

[lexington]

Originally Posted by Joel

2. I've also been a bit annoyed at the difficulty in getting any reasonable beam weapons in the ST 25+ range using the rules in Pyramid 3/37. They all seem kind of crap compared to guns in the same weight class. I know this is due to cube root scaling for damage vs. energy for beams, so my question is really the reason for this scaling. Why are larger beam weapons so incredibly energy in-efficient compared to projectile weapons?

As far as ST goes it seems that in GURPS the biggest cannon type weapons, beyond 100 pounds, usually get a huge discount on their ST value but for some reason the Pyramid system doesn't do so. For example a 251 pound minigun is ST29 in High-Tech but would have ST38 using the Pyramid formula. A coefficient of 1.8 seems to be more faithful to High-Tech.

Originally Posted by Joel

that must be some heavy electromagnetic armor

Makes sense, you need enough metal to cover the entire suit all over again.

[Gold & Appel Inc]

Originally Posted by Joel

reactor instead of E-cell (80 lbs, at most [it doesn't say fusion reactor, but it works alot like one and 100 lb fusion reactors are available at the TL])

Does that include enough shielding to avoid cooking the suit's operator? I don't think the external PF covers that, and it might account for a lot of the extra weight...

Originally Posted by Joel

electromagnetic armor (unknown weight)

that must be some heavy electromagnetic armor.

Yeah, but it's double DR vs shaped charge warheads (which anybody in possession of will use against battlesuits), which do a base 5d+5 x 3 Crushing with a (10) armor divisor on a direct hit, plus incendiary and a linked explosion with frag, in the 25mm size at TL 10. That brings the difference between the two suits to DR 10 vs DR 30, or a 200% increase with a (slightly) greater than 0% chance of completely bouncing the hit. If you're dealing with the TL 10^ Heavy Plasma Gun it gets even better, making the difference between some vulnerability and complete protection.

[Ulzgoroth]

Originally Posted by Joel

I just see very little reason a military would spend all that extra money, the only real meaningful advantage is the reactor (it's a big one though). The heavy armors just seem kind of understated.

Well, on one hand, consider the protection difference. The heavy suit is effective against 15mm and 18.5mm HEMP, which will go through the commando suit like tissue paper unless it's coated in RAP. Similarly, it's a near-stop against a Portable Rail Gun (though that's devalued if the opposition remembers that they can use boosted damage on EM guns), and protects against close hits from 64mm thermobaric grenades. It's also proof against semiportable plasma guns with EMA up, and provides core protection against them even with EMA down.

You also start appreciating that extra ST more if you're packing a 70+ pound squad support weapon, 35 pounds of rocket launcher or 75 pounds of mortar box, and ammo. Or hauling around a 160-pound 64mm mortar box!

The heavy suit also offers +2 basic move, which is fairly significant, though the super jump is weaker.

[Joel]

I'll buy the special armour being heavy but it still leaves it entirely ineffective vs. a 15mmCL Anti-Materiel Rifle or Heavy Chaingun with ETC & APEP (the later a weapon Commando Battlesuiters are likely to use) at 22d+1 (3), and the less said about ETK the better.

I can see that most of the extra strength might end up just making up for the increase in size & weight. I still have a hard time believing the reduced protection vs. radiation & pressure was intentional, I can't see any reason it would be lower priority for the larger suit and it's not like there aren't other oversights in UT (loaded magazines that weigh less than half what the bullets in them weigh etc.).

[smurf]

I prefer the Scout Model for the movement.

The real difference is move over armour. Of course the BSuit can carry bigger guns so to speak.

[Fred Brackin]

Originally Posted by Joel

reactor instead of E-cell (80 lbs, at most [it doesn't say fusion reactor,

.

No, it _says_ radiothermal generator. That's more commonly referred to as an RTG and it's not really much like a reactor. In particular it needs little shielding and no maintenance.

The power system might lead to one of the possible advantages which is endurance in the field. More air, more food, more ability to carry stuff, faster integral movement without support vehicles and no power worries.

In particular note the ST27 Semi-portable Plasma Gun. That's a yes for Heavy but a no for the Commando unless the wearer is unusualy strong (possibly due to other augmentation).

The light suits probably do get more use than the heavies but alot of that would be mass. Heavies won't do well indoors.

[lwcamp]

Originally Posted by Joel

2. I've also been a bit annoyed at the difficulty in getting any reasonable beam weapons in the ST 25+ range using the rules in Pyramid 3/37. They all seem kind of crap compared to guns in the same weight class. I know this is due to cube root scaling for damage vs. energy for beams, so my question is really the reason for this scaling. Why are larger beam weapons so incredibly energy in-efficient compared to projectile weapons?

Physically, both energy weapons and projectile weapons should have a cube-root scaling of penetration (at least in the range of 0.5 to 1.5 km/s of projectile speeds, where high powered rifles and cannon seem to work). The reason is pretty simple - to remove a given volume V of material, you need to input a certain amount of energy E, say
V = E/Y
where Y could be the yield strength or energy of vaporization or something with units of pressure or energy/volume. For projectiles, this is the energy needed to excavate a cavity via ductile deformation - pushing the material away to the side - energy weapons may use a similar or a different mechanism. Now the volume removed will be the area of the hole times its penetration
V = A P = (pi/4) W^2 P
where W is the hole width. For a number of physical reasons, you expect the aspect ratio R = P/W to be more or less unchanged as you scale the gun up or down. So substitute W = P/R and you get
V = (pi/4) P^3 / R^2
and
E = (pi/4) Y P^3 / R^2.
Solving for P, we get
P = (E R^2 (4/pi) / Y)^(1/3),
or a cube root penetration scaling with energy.

This scaling gets a bit wonky at low projectile velocity, where penetration is effected by pushing the armor material forward until it cracks, rather than to the side. So it doesn't really work for modern pistols, ancient muskets, arrows, spears, quarrels, axes, swords, or clubs. Since that is most of the weapons modeled in GURPS, it is perhaps not surprising that they adopted a penetration scaling more appropriate to the more commonly used weapons.

Luke