Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 02-01-2019, 04:17 PM   #1
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default [Spaceships] Fixing ballistic weapons in tactical combat

The way ballistic weapons work in tactical combat contains a number of oddities, both in terms of internal logic and in comparison to the basic space combat system:
  1. In the basic space combat system, ballistic weapons have hard range limits. In the tactical combat system, shells and missiles can drift forever.
  2. In the basic space combat system, fixed mount missile launchers have a limited firing arc, just like other fixed mount weapons. In the tactical combat system, they have no suck limitation and appear to get a free +2 to to the attack roll.
  3. Some of the delta-V values given for missiles make little sense.
Some proposed fixes:
  1. Limit the range in tactical combat too. This can represent the need for active guidance from the firing ship. Suggested range limits are 200 miles if the weapon's range in the basic system is Close; 1,000 miles if Short; 5,000 miles if Long, or 20,000 miles if Extreme. If you don't want these to be hard limits, a -3 penalty to attacks outside the weapon's effective range is probably fair.
  2. This is simple: just limit missile firing arcs the same way beam weapons are limited. I would tend to assume this is an issue with how the guidance systems are designed, so a ship that fires missiles needs to keep its launchers pointed towards the target throughout the missile's flight. Again, if you don't want this to be a hard constraint, you could merely apply a -3 penalty to the attack roll if the target isn't in the right arc.
  3. Halve missile thrust and delta-V below TL9. Also, don't automatically double delta-V for large missiles, however missiles can be designed with the "multistage" option, which doubles delta-V but halves effective caliber for damage purposes.
Thoughts on these fixes? Does anyone have other things in the tactical combat system they'd like to fix?
Michael Thayne is online now   Reply With Quote
Old 02-01-2019, 06:04 PM   #2
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Michael Thayne View Post
[*] In the basic space combat system, fixed mount missile launchers have a limited firing arc, just like other fixed mount weapons. In the tactical combat system, they have no suck limitation and appear to get a free +2 to to the attack roll.
I've always held that missiles get no bonus for their launchers being fixed or not, and even in the basic combat system can fire in any direction, but this is a house rule.

Quote:
[*] Limit the range in tactical combat too. This can represent the need for active guidance from the firing ship. Suggested range limits are 200 miles if the weapon's range in the basic system is Close; 1,000 miles if Short; 5,000 miles if Long, or 20,000 miles if Extreme. If you don't want these to be hard limits, a -3 penalty to attacks outside the weapon's effective range is probably fair.
I don't see the need. If you fly into a salvo of shells, tough luck. I would change the rule for shells so that they must attack any eligible target unless it has (in the GM's opinion) functional IFF that the shells would recognise as friendly.

I just assume that in the basic system ships are assumed to avoid salvos of shells. If firing at ballistic targets (stations, drifting ships, etc.), I'd not apply a range limit.
Quote:
[*] This is simple: just limit missile firing arcs the same way beam weapons are limited. I would tend to assume this is an issue with how the guidance systems are designed, so a ship that fires missiles needs to keep its launchers pointed towards the target throughout the missile's flight. Again, if you don't want this to be a hard constraint, you could merely apply a -3 penalty to the attack roll if the target isn't in the right arc.
If you do this, with this logic, if a ship manoeuvres such that the launcher now faces off-target, the missiles should automatically miss then. This is going to be a major issue in tactical combat.
Quote:
[*] Halve missile thrust and delta-V below TL9. Also, don't automatically double delta-V for large missiles, however missiles can be designed with the "multistage" option, which doubles delta-V but halves effective caliber for damage purposes.
This makes missiles quite different in tactical combat from basic combat.

Problems I do have with tactical combat:

The scale factor table (p.32) is wrong (the factors for 1-minute and 10-minute turns is x5 too high).

The range tables in tactical combat scale at a different rate to the range assumptions in Basic Space Combat. The final row on the Laser table is also weird, which I presume is just a cut/paste error.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is offline   Reply With Quote
Old 02-01-2019, 06:23 PM   #3
Ulzgoroth
 
Join Date: Jul 2008
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Michael Thayne View Post
The way ballistic weapons work in tactical combat contains a number of oddities, both in terms of internal logic and in comparison to the basic space combat system:
  1. In the basic space combat system, ballistic weapons have hard range limits. In the tactical combat system, shells and missiles can drift forever.
  2. In the basic space combat system, fixed mount missile launchers have a limited firing arc, just like other fixed mount weapons. In the tactical combat system, they have no suck limitation and appear to get a free +2 to to the attack roll.
  3. Some of the delta-V values given for missiles make little sense.
Some proposed fixes:
  1. Limit the range in tactical combat too. This can represent the need for active guidance from the firing ship. Suggested range limits are 200 miles if the weapon's range in the basic system is Close; 1,000 miles if Short; 5,000 miles if Long, or 20,000 miles if Extreme. If you don't want these to be hard limits, a -3 penalty to attacks outside the weapon's effective range is probably fair.
  2. This is simple: just limit missile firing arcs the same way beam weapons are limited. I would tend to assume this is an issue with how the guidance systems are designed, so a ship that fires missiles needs to keep its launchers pointed towards the target throughout the missile's flight. Again, if you don't want this to be a hard constraint, you could merely apply a -3 penalty to the attack roll if the target isn't in the right arc.
  3. Halve missile thrust and delta-V below TL9. Also, don't automatically double delta-V for large missiles, however missiles can be designed with the "multistage" option, which doubles delta-V but halves effective caliber for damage purposes.
Thoughts on these fixes?
Number 1 and 2 are both nonsensical.

Point 1 is not a problem in the tactical rules, it's a simplification in the basic rules - the 'hard' range limit is representative of how far away the weapon is effectively capable of generating hits. For guns, this is totally fine (though the numbers in principle should be more context-dependent), though it's a big problem for missiles that are capable of throttling (and re-igniting) their propulsion for a boost-drift-attack flight plan.

Point 2 is a bit of a rules hash, but your 'fix' is not technologically justifiable. That kind of guidance system is relatively obsolescent for planetside missiles that engage targets faster than tanks. And space ranges make it much, much worse. Space missiles can't make effective terminal maneuvers without on-board homing. On the other side of things they almost certainly have the guidance capability for off-bore firing, because the range also means that the missile's on-board sensors likely won't be satisfactory for the initial stages of the flight.

My recommendations: don't try to fix 1, it's fine. For 2, don't use turrets with conventional missiles, only fixed tubes. Modern ships can have VLS, spaceships not being able to would be weird. Your call whether to let them have the +2.
Quote:
Originally Posted by Michael Thayne View Post
Does anyone have other things in the tactical combat system they'd like to fix?
There's points where I consider Spaceships rules to be catastrophically broken or literally impossible to follow. But it's probably not productive to drag things there.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 02-01-2019, 08:46 PM   #4
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Rupert View Post
I don't see the need. If you fly into a salvo of shells, tough luck. I would change the rule for shells so that they must attack any eligible target unless it has (in the GM's opinion) functional IFF that the shells would recognise as friendly.

I just assume that in the basic system ships are assumed to avoid salvos of shells. If firing at ballistic targets (stations, drifting ships, etc.), I'd not apply a range limit.
The trouble here is that yes, shells are supposed to have thrusters for guidance, but the amount of delta-V has to be pretty small—and hexes in tactical combat are pretty large. Maybe it would be okay if you had to designate a target at launch, but even then in extreme cases you run into issues with physical limitations of the weapon limiting accuracy.

Quote:
This makes missiles quite different in tactical combat from basic combat.
This, admittedly, isn't a case where I'm trying to make tactical and basic combat consistent. It's more an issue of the tactical combat system making no sense on its own terms. It makes no sense for bigger missiles to automatically get a delta-V boost, unless they're using higher ISP engines that can't be miniaturized, but the delta-V stats for smaller missiles already make no sense unless 16 cm missiles have quite high ISP for a high-thrust system.

OTOH halving caliber might be to harsh. As a compromise, you could reduce caliber by two steps instead, with a minimum initial caliber being 24cm. So 24cm becomes 16cm, 28cm becomes 20cm, and so on.
Michael Thayne is online now   Reply With Quote
Old 02-01-2019, 08:51 PM   #5
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Ulzgoroth View Post
Number 1 and 2 are both nonsensical.

Point 1 is not a problem in the tactical rules, it's a simplification in the basic rules - the 'hard' range limit is representative of how far away the weapon is effectively capable of generating hits. For guns, this is totally fine (though the numbers in principle should be more context-dependent), though it's a big problem for missiles that are capable of throttling (and re-igniting) their propulsion for a boost-drift-attack flight plan.

Point 2 is a bit of a rules hash, but your 'fix' is not technologically justifiable. That kind of guidance system is relatively obsolescent for planetside missiles that engage targets faster than tanks. And space ranges make it much, much worse. Space missiles can't make effective terminal maneuvers without on-board homing. On the other side of things they almost certainly have the guidance capability for off-bore firing, because the range also means that the missile's on-board sensors likely won't be satisfactory for the initial stages of the flight.

My recommendations: don't try to fix 1, it's fine. For 2, don't use turrets with conventional missiles, only fixed tubes. Modern ships can have VLS, spaceships not being able to would be weird. Your call whether to let them have the +2.
I'll take your advice on point 2 (argh, this means I have to decide if the +2 applies or not...) But I'm not willing to let go on point 1 as applied to shells, there are clear logical issues involving just how much delta-V these shells are supposed to have (as I noted above). And applied to missiles, it results in missiles that are vastly more effective in the tactical combat system, compared to the basic system. But maybe a more logical fix would be saying missile engines can't be shut down, or can't be restarted after shutdown, or at the very least have a limited amount of time they can drift?

Quote:
There's points where I consider Spaceships rules to be catastrophically broken or literally impossible to follow. But it's probably not productive to drag things there.
If they're tactical-combat specific, I'd be very curious about them and consider them totally on-topic.
Michael Thayne is online now   Reply With Quote
Old 02-01-2019, 09:09 PM   #6
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

It's worth spelling out the logic around missile delta-V for TL9+ missiles. They do the same damage as a same caliber bomb (per Spaceships 4), and a bomb weighs 1/3 what a missile weighs. A standard-sized upper stage also weighs about 1/3 of the spaceship's weight. So you can think of a missile as a very small spaceship with a "bomb" upper stage. To get 10 mps delta-V from a single lower stage using HEDM rockets, you need 13 fuel tanks (13 x 1.6 x 0.5 = 10.4 mps). That leaves only one "slot" for the engine, which would yield an acceleration of only 5G, but this can be justified as a variant engine optimized for use in missiles. It would make sense if the higher-thrust version cut some corners, such that it couldn't be shut down or otherwise was difficult to use for boost-drift-attack flight plan.
Michael Thayne is online now   Reply With Quote
Old 02-01-2019, 09:30 PM   #7
Ulzgoroth
 
Join Date: Jul 2008
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Michael Thayne View Post
The trouble here is that yes, shells are supposed to have thrusters for guidance, but the amount of delta-V has to be pretty small—and hexes in tactical combat are pretty large. Maybe it would be okay if you had to designate a target at launch, but even then in extreme cases you run into issues with physical limitations of the weapon limiting accuracy.
Quote:
Originally Posted by Michael Thayne View Post
I'll take your advice on point 2 (argh, this means I have to decide if the +2 applies or not...) But I'm not willing to let go on point 1 as applied to shells, there are clear logical issues involving just how much delta-V these shells are supposed to have (as I noted above).
What issues do you see with shells, delta-V, and unlimited range? Shells have negligible delta-V for sure, but they don't use up any of that delta-V as they travel. They're just drifting from when they're fired until they encounter a target and make an attack.
Quote:
Originally Posted by Michael Thayne View Post
And applied to missiles, it results in missiles that are vastly more effective in the tactical combat system, compared to the basic system. But maybe a more logical fix would be saying missile engines can't be shut down, or can't be restarted after shutdown, or at the very least have a limited amount of time they can drift?
My view is that the basic system cheats missiles of their core functionality, and generally that where SS1 and SS3 differ, SS3 is superior. YMMV.

At some TLs there are definitely technical rationales for missiles to be one-burn-only. But there are also very strong motivations for them to be built to be able to boost, drift, and perform terminal attack maneuvers, and that's achievable at any TL where you'd have spaceships firing missiles...
Quote:
Originally Posted by Michael Thayne View Post
If they're tactical-combat specific, I'd be very curious about them and consider them totally on-topic.
I can't think of any that are introduced by the tactical combat system. Aside from the 'stack up literally every missile in your fleet in one barrage' trick, which is a bit of a feature-or-bug situation.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 02-01-2019, 09:37 PM   #8
Ulzgoroth
 
Join Date: Jul 2008
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Michael Thayne View Post
It would make sense if the higher-thrust version cut some corners, such that it couldn't be shut down or otherwise was difficult to use for boost-drift-attack flight plan.
If you're looking for an excuse to be generous enough to let the missiles work as statted, you could argue that the corner cut is operational lifespan. A spaceship rocket can be kept in service essentially forever with maintenance and refueling. A missile rocket can be scrap after you put 10 mps through it.

(Of course, that or indeed many other imaginable corner cuts would invite the question of why you don't cut the same corners for disposable STO boosters.)
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 02-01-2019, 10:36 PM   #9
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Quote:
Originally Posted by Ulzgoroth View Post
What issues do you see with shells, delta-V, and unlimited range? Shells have negligible delta-V for sure, but they don't use up any of that delta-V as they travel. They're just drifting from when they're fired until they encounter a target and make an attack.
If shells have no burn points even on a 10 mile scale, that means they can't correct for initially being 10 miles off-target. But if you're using a 100 mile scale, and a shell happens to enter the hex of an enemy spaceship purely by accident, that's totally consistent with the shell being 10 miles off from the target. Or even 50 miles off. Maybe you could adopt a rule that if a shell and ship cross paths totally accidentally, the shell attacks on a 6 or less on 3d?
Michael Thayne is online now   Reply With Quote
Old 02-01-2019, 10:53 PM   #10
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [Spaceships] Fixing ballistic weapons in tactical combat

Revised proposal for limiting the range of ballistic weapons: shells and bombs can drift for up to 10 minutes before their odds of hitting anything drop dramatically (in most cases the GM should just remove them from the map). For standard TL9+ missiles, their powerful HEDM engines cannot be shut down until they run out of burn points. After that point, they become bombs, with sAcc in space equal to TL-11, and in most cases removed from the map after 10 minutes.
Michael Thayne is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 06:38 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.