Vehicular Firepower

[David Johansen]

Okay, so some of you may remember that back in the day GURPS vehicle combat ran on a different scale and system than personal combat. First introduced in GURPS Humanx was a simple design system and combat that was somewhat quicker and dirtier and very similar to the mass combat system from Conan. It carried forward in Space and Riverworld.

Recently I ran a couple sessions with the Modular Mecha rules from Pyramid and while it was okay, it wasn't quite what the players wanted. Too much math in the to hit and damage calculations for their tastes. Yes, it's just GURPS combat but it didn't really meet their expectations.

Which brings me to ask whether anyone would be interested in a basic vehicle design and combat system along the lines of the old GURPS Space system. I think combat might be more along the lines of the Space Opera Combat system.

[Phantasm]

I welcome anything that lets us develop vehicles quickly and work out vehicular combat with a minimal of fuss. :)

[David Johansen]

My basic proposal would be that vehicles be primarily designed by volume with weight being figured primarily by structure and armor and cost being figured by multiplying weight by a factor representing the complexity, usage and TL of the design. When has the cost of anything actually equaled the cost of all the parts?

Mechanical Systems like power plants would have an output per unit volume, a minimum volume, and a fuel consumption rate.

I'm not sure if I'd bother with a firepower to damage conversion beyond, perhaps a flat 10d per fp. It might be good to have a Troop Strength conversion or integrate with mass combat a bit so your super mech -12 can blast away companies of infantry.

Armor and Structure would be combined. Sure there's problems with that but we have GURPS Space Ships and GURPS Vehicles may even come out before I die. I think putting a size cap on volume by TL and mode and a "it matches the damage scaling curve" hand wave would get us around the cube square law.

The combat stats would be speed, agility, armour, and weapons. I think weapons would need a range and damage stat and perhaps a rate of fire. I'm thinking tactical representation is useful for big larger actions, so I want to keep it possible without getting into tracking every yard of movement.

Damage should probably be done with a simple table per vehicle type. No specific hit locations here just increasingly brutal performance reducing critical hit descriptions.

So that's a broad overview, any thoughts?

[Fred Brackin]

Originally Posted by David Johansen

My basic proposal would be that vehicles be primarily designed by volume with weight being figured primarily by structure and armor and cost being figured by multiplying weight by a factor representing the complexity, usage and TL of the design. When has the cost of anything actually equaled the cost of all the parts?

So that's a broad overview, any thoughts?

It sounds like you want a design system much more complex than Spaceships with a combat system that's more simple? That sounds odd to me.

[Ulzgoroth]

I'm not at all interested in a vehicle combat system that's simpler than GURPS combat.

Something that did away with some of the rough edges that result from how GURPS vehicular combat is added on to GURPS personal combat could be good, if it doesn't compromise compatibility with people on foot using personal combat rules.

[David Johansen]

I guess it kinda is two projects. The first is a simple vehicle design system loosely based on the one from GURPS Space the objective being a system that lets you build and customize vehicles and gets the performance in the ball park. Spaceships is more complex than what I have in mind but that may be a matter of opinion. I might try to make it integrate with the standard combat stats if it doesn't prove to be too much work.

Project two is a simple vehicle combat system that's driven by success rolls and doesn't get into things like penetration modifiers, linked damage, and follow-up damage. This would resemble the Space Opera Combat System from Lensmen and Compendium 2.

I realize that these things won't appeal to everyone and are somewhat redundant with Space Ships and Vehicle Design but I think enough people might find them useful to make it worth putting something together.

[Lord Azagthoth]

One thing I introduced in my campaign was Tactical SM (or Profile). Maneuvering around a vehicle to get a larger profile to get that needed bonus to hit, or dodging and maneuvering away, giving your opponents and penalty to hit because you show them your smallest profile.

It does, however, need you to give each vehicle 6 SM's (front, back, dorsal, ventral, port, and steer).

Using this system also simplified which weapons could be fired because you know at which angle your opponent is.

[David Johansen]

I was thinking that the piloting / maneuvering contest would determine who gets to decide relative facings / bearings for the round. I'm thinking that rather than setting size modifiers for each side, bearing in mind a simple / abstract combat system, you'd be able to get a to hit bonus from the contest as well.

But we're talking about longer rounds here too. Probably a different time scale for personal (standard combat), ground, air, orbit, and space. Firepower covers many shots over time, so you generally won't miss as the result of a failed attack roll, you'll just do less damage.

[Ulzgoroth]

Originally Posted by David Johansen

But we're talking about longer rounds here too. Probably a different time scale for personal (standard combat), ground, air, orbit, and space. Firepower covers many shots over time, so you generally won't miss as the result of a failed attack roll, you'll just do less damage.

This'll make it not really capable of modeling many forms of combat - the difference between 'hit' and 'not hit' is often the most important one. Sacks of hitpoints might work for age-of-sail-and-cannon but it doesn't much work for, for instance, the age of guided missiles. Or submarine battles.

Also, how are you handling DR? 'Penetrated' vs. 'not penetrated' is also important.

[Fred Brackin]

Originally Posted by David Johansen

I guess it kinda is two projects. The first is a simple vehicle design system loosely based on the one from GURPS Space the objective being a system that lets you build and customize vehicles and gets the performance in the ball park. Spaceships is more complex than what I have in mind but that may be a matter of opinion. I might try to make it integrate with the standard combat stats if it doesn't prove to be too much work.
.

I do not believe that any system that takes into account both volume and mass can be simpler than Gurps Spaceships while being at all accurate.

Spaceships is _really_ simple. I can design ships in my head and then just do a couple of minutes of table look-ups. The Space 1e system definitely was not simpler.

If I was going to simplify Spaceships combat I would do it by making things less abstract and getting rid of the variable time units and relative distance bands. You can spend more time calculating those than you would just running straight Gurps combat.

You would lose much of the "maneuver" element but realistically there's little to maneuver for or against and only the most fantastic accelerations (more than the 500Gs of sub-warp) will change distance meaningfully on a short-term basis..