Top 10 questions I can't figure out before releasing my spreadsheet

[TheDS]

Greetings, all! I’m almost finished making a spreadsheet with which to build ships according to the new rules, and I’ve run across a few rules snags and other general questions that prevent me from finishing. I’ll go over them briefly.

1. Estimated Mass: I realize this is just an estimate, but 2.0 as an average density has been very low for everything (but tankers), resulting in overestimates for acceleration. As a quick fix, a better average seems to be 3.0. For a closer estimate, see directly below.

Average Mass Estimates -
Tanker: 1.5
Passenger ship: 2.5
Warship: 3.0
Cargo ship: 4.0
No Jump Drive for 100+ dtons: add 0.5
Boats (under 100 dtons, no jump drive): add 1.0.
Ships expecting to haul Heavy Cargo (25.0) can’t use this estimation (varies too much).

I’ve added this to my sheet, and thought I’d offer it as a solution.

The only reason it even matters is that when you’re trying to decide how much acceleration your ship has, 2.0 is ALWAYS an overestimate (excepting tankers); eg, I try for 6G and wind up with 3-5G. (I can’t have the sheet let you directly choose your acceleration because it’s an iterative process and the computer doesn’t want to handle that.)

2. There is no mention of limitations to G-rating. In most past editions, Traveller ships haven’t been faster than 6G, though TL plays a part in what G-compensators you have available, and G-compensators aren’t mentioned at all. So, is there a limit to accel?

Related to that, in some editions of Traveller, there’s a minimum armor level for a given accel; I presume you omitted this intentionally? (eg, 10*G; if you want 6G, you need DDR60 armor.)

3. There seems to be no difference between the two Repulsor Bays except TL. Was the higher tech one supposed to be lighter/cheaper by half, maybe? Perhaps deflect more missiles? Perhaps be 50 dton?

Related to that, being able to flat-out repel 100 missiles seems like it might be... oversimplified? Was a slightly more detailed rule left out due to space or simplicity concerns? For instance, it occurs to me that a high-speed missile would be harder to deflect, and Repulsors might also be good at pushing away enemy fighters. And what happens to deflected missiles, do they explode, come back for a second pass next round, or what? Perhaps the Repulsor should allow you to adjust the course of the targeted missile; essentially, alter its future-position marker, say by up to 500 ton-spaces, but I guess that would require some explanation.

4. I have noticed a major discrepancy in regards to Air Speed, because it’s based on surface area. Firstly, you get Needle/Wedge configs going slower than Sphere configs with everything else being equal. This should be based on frontal surface area rather than total surface area. Second, large ships go faster than slow ships, because thrust goes up as mass does, and mass gets cubed when surface area gets squared. Perhaps this is realistic, as I don’t see too many Cessnas outrunning 747s, but on the other hand, fighters outrun B-52s easily.

This is really smacking my willing suspension of disbelief upside the head. I don’t have a quick solution for you, either, other than using a formula from an older edition of Traveller.

5. Beam lasers vs Pulse lasers. If the energy in any given beam laser could be accumulated for, say, a minute, then fired off all at once in a really short burst, wouldn’t the resulting shot be a lot more powerful? A steady beam would have a tough time exceeding the heat-dissipation rate of what you’re shooting at, and therefore do no damage, while the pulse would impart all that energy so quickly that the impact point explodes.

In a game which keeps track of heat, beam lasers would be useful for warming your target, perhaps to the point where his recycling system dies (literally; a recycling system has bacteria in it, and they must be tended carefully, even in modern ships) and the ship must either find a place to put down in the next week, or risk everyone dying. Theoretically (at least, if you watch enough B5) you could use one to cut a ship up with a minimum of damage to it (until you accidentally cut open the reactor), but in a universe where ships don’t worry about heat unless they’re skimming stars, beam lasers are pretty much useless.

So for that reason, they should AT LEAST have their damage reduced, and be relegated to anti-missile defense, since missiles don’t have a lot of heat-capacity and knocking out their guidance system or something like that is a lot more feasible. (But then you wouldn’t be able to use the laser on more than 1 or 2 missiles per turn, I fear.)

Yeah, I know you’re gonna say that OT and MT have historical precedence, but that doesn’t mean they’re right.

6. Collision damage seems to be incredibly high, such that even at minimum speed, a 10-ton fighter should just about vaporize a 30,000-ton battleship. Of course, if armor protected with DR instead of DDR, having 10 times the armor would go a long way to resolving this in my mind. True, it’s not directly a ship-design problem, but if ships are going to be vaporized by love-taps, who’s gonna even play?

7. It occurs to me that since fighters and other boats are intended to be simple devices with limited range, that putting a reactor in one is a bit overkill, and makes them unnecessarily expensive to boot. Would it be better to power these things with batteries, since they don’t need reaction mass? I’d think this was a good idea for missiles and sensor drones too, in case some one wants to make something like that.

Using information from Vehicles 3e (since I couldn’t find anything in 4e that would tell me the values for batteries), at TL10, a dton of battery delivers 250 MWh of power, weighs 25 tons, and costs M$5. TL9 could deliver 200 MWh and TL11 could deliver 300 MWh (actual values are 187.5 and 312.5). These are the rechargeable power cells, of course. My initial rough guesstimates would give a fighter an endurance of about 15-20 hours at max output – all weapons blazing, but the extra mass would slow them down a little. Still, less waste heat means the craft is a lot harder to spot, perhaps giving an additional -1 or -2 against enemy sensors, for a craft that’s not going to need days of endurance anyway.

...I just noticed that 3e batteries are extremely expensive compared to the fusion reactors in GT:ISW; part of this is due to my assumption of filling an entire dton with battery, and the book’s assumption that the space allocated for reactors allows for maintenance and other supporting gear, and part of it is the immense cost savings of higher tech reactors. (Actually, this applies to the weight too, which I also really high.) By any chance, if you think batteries should be included in this design sequence, could you pass along the relevant section of Vehicles 4e so I can include them?

8. Speaking of fighters, if I want launch tubes, what kind of hanger should I build to accommodate them? Will Vehicle Bays be sufficient if they’re all alike, or is a full-blown Hanger needed?

9. Speaking of Hangers and Vehicle Bays... they’re awful small, aren’t they? I know from the 5 years I lived on a large ship (LHD-5) that even the davits that were for particular boats were easily twice as large as the boat stored there, and the hanger could easily see 3/4 of its volume unused even when there was barely enough room to walk between aircraft. (The overhead had to be tall enough to accommodate helos, and rotors don’t take up a lot of actual space.) Was this a nod to all those players who just see a hanger size and cram ships of that size into them, or are the carried craft being mounted on the outer hull so they really don’t take up 2-4 times their volume, or was this a goof? (Or are the subcraft inflatable, like lifeboats? ;) )

10. There is no suggested value for Fuel Purification Plants. I have gone the route of specifying the number of hours to purify the whole tank, and the computer figures out how many spaces are needed to do that. Picking a default value has a couple complications.

First, what’s the typical time between refueling and jumping? You’d generally refuel from a gas giant, and then leave and jump, so finding a value from that should be easy, if you know your accel, so this is just a matter of looking up some stuff, if applicable. Probably 3-12 hours as a rough guestimate.

Second, does ALL the fuel have to be purified to make a jump, or can I start the jump while I’m purifying, just so long as I get it all done 150 hours later, before emergence? This would make FPPs absolutely insignificant – 1 space would be needed for up to about 5000 dtons of ship - whereas they are simply virtually useless now (typically being less than 1% of the hull; I’ve been using 12 hrs as a default so far).

I’ve saved the ship-specific questions for another post, since I’m not done compiling them, and I’m about to bump into the 10,000 character limi

[sn0wball]

Originally Posted by TheDS

First, what’s the typical time between refueling and jumping? You’d generally refuel from a gas giant, and then leave and jump, so finding a value from that should be easy, if you know your accel, so this is just a matter of looking up some stuff, if applicable. Probably 3-12 hours as a rough guestimate.

Second, does ALL the fuel have to be purified to make a jump, or can I start the jump while I’m purifying, just so long as I get it all done 150 hours later, before emergence?

Well, I can only base my answers on sources older the ISW, which your post is about, as I guess, but traditionally all jump fuel is consumed as you enter jump space. Usually this is explained as a kind of exchange of matter and/or energy between the two different universes.

As to the time needed between refueling and jumping - this will be at least the time it takes you to leave the 100 D radius of the gas giant in question, right ? For Jupiter, this is 15.000.000 km (=0.1 AU), for Neptune or Uranus it is 5.000.000 km.

If you assume 1 G accell as a default, then you´ll need 20 hours / 11 hours. Note that this is the fastest way for jumping. You might as well add time to align your vector to the target system, unless you care to ignore the vector problem.

[TheDS]

Yes, you've grasped the question perfectly, and your timing estimates are probably the answer I was looking for (and I was too lazy to figure them out for myself). I guess I'll have to make a suggested size based on the ship's accel, and the "average" world to be refueled from (typically gas giant, but maybe also ocean refueling, hence my lower estimate above).

I'm still not sure I can call the other part of the question answered yet, since there are reasons both could be true, tho like you, I'm expecting to need all the fuel at once, if only for gameplay reasons.

[thtraveller]

Originally Posted by TheDS

The only reason it even matters is that when you’re trying to decide how much acceleration your ship has, 2.0 is ALWAYS an overestimate (excepting tankers); eg, I try for 6G and wind up with 3-5G. (I can’t have the sheet let you directly choose your acceleration because it’s an iterative process and the computer doesn’t want to handle that.)

It should be able to do that, it is a common spreadsheet requirement. Excel has it in tools-options-calculation-iteration.

Related to that, being able to flat-out repel 100 missiles seems like it might be... oversimplified?

It's probably just that the laser turrets it displaces could reliably take out 100 missile per round.

5. Beam lasers vs Pulse lasers. If the energy in any given beam laser could be accumulated for, say, a minute, then fired off all at once in a really short burst, wouldn’t the resulting shot be a lot more powerful? A steady beam would have a tough time exceeding the heat-dissipation rate of what you’re shooting at, and therefore do no damage, while the pulse would impart all that energy so quickly that the impact point explodes.

It would also exceed your laser's heat dissipation rate and also overload/burn out the laser.

In a game which keeps track of heat, beam lasers would be useful for warming your target,

And at least twice as good at warming the firing ship as the laser isn't 100% efficient. But its generally peanuts compared to the reactors and thrusters.

6. Collision damage seems to be incredibly high, such that even at minimum speed, a 10-ton fighter should just about vaporize a 30,000-ton battleship. Of course, if armor protected with DR instead of DDR, having 10 times the armor would go a long way to resolving this in my mind. True, it’s not directly a ship-design problem, but if ships are going to be vaporized by love-taps, who’s gonna even play?

Blame Newton! Collision damage is based on the real world kinetic energy formula. Though reactionless thrusters are really to blame.

Using information from Vehicles 3e (since I couldn’t find anything in 4e that would tell me the values for batteries),

I think they were reduced in energy density by a factor of ten in 4E.

9. Speaking of Hangers and Vehicle Bays... they’re awful small, aren’t they?

This has been standard gurps:vehicles hangars rules for a long time.

10. There is no suggested value for Fuel Purification Plants. I have gone the route of specifying the number of hours to purify the whole tank, and the computer figures out how many spaces are needed to do that. Picking a default value has a couple complications.

I think most of the IW ships had fuel processors equal to tank size/50 giving a 10 to 15 hour refuel time.

First, what’s the typical time between refueling and jumping? You’d generally refuel from a gas giant, and then leave and jump, so finding a value from that should be easy, if you know your accel, so this is just a matter of looking up some stuff, if applicable. Probably 3-12 hours as a rough guestimate.

http://www.thtraveller.dsl.pipex.com/iw/TravTime.htm (temporarily)

[TheDS]

Originally Posted by thtraveller

It should be able to do that, it is a common spreadsheet requirement. Excel has it in tools-options-calculation-iteration.

Yeah, it should, but every time I've tried it, Excel crashes.

It's probably just that the laser turrets it displaces could reliably take out 100 missile per round.

Doh! Good reason. Still got the problem of there not being a difference between the two different repulsors.

It would also exceed your laser's heat dissipation rate and also overload/burn out the laser...And at least twice as good at warming the firing ship as the laser isn't 100% efficient. But its generally peanuts compared to the reactors and thrusters.

Well sure, if you want to bring realism into it... :) But to disagree with you for a moment: a ship needs to dissipate ALL the energy its reactor produces, so running your laser in beam-mode isn't going to put any strain on your radiators/heat-sink (in fact, it may help them). But when someone's shining a big, hot spotlight on you, or several of them, your ship will have to be designed to take this into account or it will heat up. Having radiators deployed will make things worse since the laser is a spotlight and just gets more area to radiate onto.

Blame Newton! Collision damage is based on the real world kinetic energy formula. Though reactionless thrusters are really to blame.

If I'm colliding my 10 dton fighter into a 30,000 dton battleship with DDR400 armor, if I take 400 off the damage, that battleship is dead, but if I take 4000 off, that battleship is more likely to survive. So I'm asking, is this one of those cases where we need to use DR instead of DDR, or is everyone gonna start making ALL their warships into 10 dton fighters with high-G, because there's no point to anything else (and thencely ruining the game)?

Supporting this argument is the text describing the Indomitable, which describes one of that class surviving a collision with a cruiser, something nearly impossible if only 400 was taken off the damage (roll REEEEALLY low).

This has been standard gurps:vehicles hangars rules for a long time.

Okay, I didn't study my Vehicles book very thoroughly when I got it; got hung up on some stupid detail in a test design I was making, and set it aside for other projects, and never got back to it.

I think most of the IW ships had fuel processors equal to tank size/50 giving a 10 to 15 hour refuel time.

I'm still not done with my work yet, but so far, processing time has been 13 or 25 hours most of the time; double-jumpers seem to lean toward the 25 hour figure. So this gives my instinctive guess of 12 hours some merit.

Thanks for the assist; keep it coming!

[thtraveller]

Originally Posted by TheDS

Supporting this argument is the text describing the Indomitable, which describes one of that class surviving a collision with a cruiser, something nearly impossible if only 400 was taken off the damage (roll REEEEALLY low).

And you believe this history as written by the victor?

[Shaper]

Originally Posted by TheDS

If I'm colliding my 10 dton fighter into a 30,000 dton battleship with DDR400 armor, if I take 400 off the damage, that battleship is dead, but if I take 4000 off, that battleship is more likely to survive. So I'm asking, is this one of those cases where we need to use DR instead of DDR, or is everyone gonna start making ALL their warships into 10 dton fighters with high-G, because there's no point to anything else (and thencely ruining the game)?

It would probably just create a doctrine towards a fairly heavy amount of point defense.

Ships are inherently limited in acceleration to a certain point, or any piece of small space debris is likely to take them out. A fighter isn't overly heavily armoured, wouldn't take a huge amount of sand to make a serious obstacle if an attack is expected, if they are pushing relatavistic speeds. Deploying them while in transit might be a lot harder to manage. Kamikaze pilots may be fairly expensive in terms of recruiting and training efforts, automated ships are essentially large missiles.

If they are moving at trackable speeds then there is a good reason for batteries full of point defense. A fairly intense field of fire could probably be laid down by a number of high ROF laser banks that are keyed to fairly short ranges. Whatever defenses are usable against missiles should be effective against fighters, otherwise space combat doctrine is going to undergo massive evolutionary changes and won't resemble traveller anyways.

Laser physics is already a bit bent for the game, collision physics might have to be bent a bit (drives that have inbuilt exponentially declining repulsion fields that slow impact damage enough to make it manageable?)

Another approach might make the thruster drives sensitive enough to each others fields that an effect similar to the repulsion field of same pole magnets actually creates a braking effect on thruster fields that are close by. The exponentially declining level of this effect is just enough to prevent proximity collisions. Of course this then brings up the potential for a staged release of the plate, but that might have other consequences.

[TheDS]

Turning the game into a non-Traveller game was the whole point of the question; rather, fear of it was. I was considering adding a stat to tell the designer how much damage their ship would do if it collided with another, and if I do go that route, and can't get a ruling by then, then I'll have to go with what I think keeps the game from being destroyed.

Game players tend to be more devious than game designers (though judging by the things I've read around here, that doesn't hold true of most GURPS writers).

Originally Posted by thtraveller

And you believe this history as written by the victor?

What, you don't? Terrans don't lie, they're the good guys.

[Shaper]

Originally Posted by TheDS

Turning the game into a non-Traveller game was the whole point of the question; rather, fear of it was. I was considering adding a stat to tell the designer how much damage their ship would do if it collided with another, and if I do go that route, and can't get a ruling by then, then I'll have to go with what I think keeps the game from being destroyed.

No idea how this is handled in the newer books, but traveller tends to be fairly physics based as much as possible.

The velocity at the time of impact and the mass of the object are going to determine the amount of kinetic energy exchanged in the collision. Unless a system is implemented to limit this (presumably for the purpouse of moving through asteroid belts, or as a form of missile defense) in some fashion, those collisions are going to be generally catastrophic for both vessels.

If collision is inevetable some attempt at adjusting vectors to increase the angle of deflection and minimize the transferred energy will probably be attempted. At the velocities required for a ramming attack, an actual impact with the target may be a fairly difficult maneuver, presuming that the kamikaze can close the gap successfully.

If this becomes a common process (large kamikaze drones), then there will probably be counter measures such as close range rockets to divert the incoming ship's trajectory. Another solution that might be possible is to use a short range field weapon to scramble the electronics of the incoming vessel, hopefully just in time to execute an evasive roll or turning maneuver.

Which of these solutions if any are feasible is beyond my ability to accurately assess, but may be worth consideration.

Actual ramming damage is going to be hard to calculate though, on a generic level due to the variances involved. A slow moving large ship may easily end up doing less damage than a fast moving small ship that has had a fair amount of time to get up to speed.

If a player in your game wants to attempt a tactic of this nature, make them run the gauntlet of defensive fire, and then have it come down to a piloting skill contest using whatever modifiers make the situation interesting would probably be the best solution. A good running start will do more damage, but may be easier to evade as course corrections will take longer to implement.

If they start getting clever and using mass sensors as homing devices being fed into a tracking/pilot program start using more aggressive countermeasures to keep the situation from getting out of control. Using large kamikaze drones is expensive, try to find ways to keep them from becoming cost inefficient to use as weaponry.

If they are doing this, they will probably end up stacking them with explosives of some kind, in which case revert to missile rules and deal with accordingly.

What, you don't? Terrans don't lie, they're the good guys.

Of course we are the good guys, always, why you can read it right here... in the history book.

[Terrypinkona]

Personally, I design my ISW ships (With the fabulous spreadsheet by DS) with enough close range weapons to -hopefully- eliminate targets coming in to ram or close range attack me. I thought, by looking at the description of the various weapons in ISW, that thats what the plasma guns were for, i.e. point defence. So I design my ships according to this. They can easily be used for secondary or tertiary armament.
Now to the point of ramming vessels to destroy the enemy--- Its not like Lepanto or Lissa ramming. Its more like the use of the Fire Ship in the Age of Sail. You are going to lose both ships. Its a kinetic kill missile. Hence the rules for avoiding by manuever.
The expense of the tactic would likely limit it, but a desperate state would probably see no harm in using captured merchants or older ships to use.
So my advice is, when designing ships, do so to protect it from this attack. Either make it fast enough to run away,or strong enough to cripple or destroy the target before it hits.