Fighters/PT Boats in the Traveller Universe

[atpollard]

I admit to enjoying the more cinematic aspects as a thought experiment over obsessing over the mechanics of the 'RAW". RAW are vital to "Tournament style" combat, but for a group of friends trying to have fun, there is a "reality" that the rules are expected to model to the best of their ability and the "suspension of disbelief" rests on the rules of the game reality more than the mechanics of the literal system.

That said, I like the IMAGE of the old TORPEDO BOAT charging towards a MONITOR or DREADNOUGHT, or the famous DIVE BOMBER with its single giant payload of destruction running the point-defense gauntlet to deliver destruction to a BATTLESHIP or CARRIER. To attempt to create that "mental image" within the "imaginary physics" of the Traveller-verse leads me to imaging a larger FIGHTER/GUNBOAT [say 30 dTons] with an enormous TORPEDO [say 5 a dTon Missile] mounted as a forward firing spinal weapon. A special purpose craft designed to deliver a precision blow to cripple the largest ships.

Perhaps, the GAME MECHANICS will dictate some other size/weapon combination. The TORPEDO simply drew from historic mental imagery as a starting point for a concept. However, it is not [IMTU or IMHO] the narrow mechanics of LBB5 [which differ from other LBBs and later Rules editions] that should be the end-all, be-all, last-word on what is "Traveller Reality" ... and especially "Traveller Possibility".

 

[kilemall]

I admit to enjoying the more cinematic aspects as a thought experiment over obsessing over the mechanics of the 'RAW". RAW are vital to "Tournament style" combat, but for a group of friends trying to have fun, there is a "reality" that the rules are expected to model to the best of their ability and the "suspension of disbelief" rests on the rules of the game reality more than the mechanics of the literal system.

That said, I like the IMAGE of the old TORPEDO BOAT charging towards a MONITOR or DREADNOUGHT, or the famous DIVE BOMBER with its single giant payload of destruction running the point-defense gauntlet to deliver destruction to a BATTLESHIP or CARRIER. To attempt to create that "mental image" within the "imaginary physics" of the Traveller-verse leads me to imaging a larger FIGHTER/GUNBOAT [say 30 dTons] with an enormous TORPEDO [say 5 a dTon Missile] mounted as a forward firing spinal weapon. A special purpose craft designed to deliver a precision blow to cripple the largest ships.

Perhaps, the GAME MECHANICS will dictate some other size/weapon combination. The TORPEDO simply drew from historic mental imagery as a starting point for a concept. However, it is not [IMTU or IMHO] the narrow mechanics of LBB5 [which differ from other LBBs and later Rules editions] that should be the end-all, be-all, last-word on what is "Traveller Reality" ... and especially "Traveller Possibility".

True enough, but I wanted a MTU where I maintained more or less the functionality of the original designs in their value proposition implied in their pricing, while making for more of what I wanted.

Why throw away 40 years of floor plans?

What I wanted increased the power of some things like small craft, so I made sure the costs went up to match. For instance, small craft armor takes 3x as much space because heavy slabs are big, and therefore more expensive as well.

My stealth rules mean small craft are the only ones that are likely to get near invisible, but that’s a lot of expense for one fragile craft.

Missiles are more capable and potentially destructive, but have a cost basis for every round.

 

[chipla]

Just FYI: You have a math error in your cost calculation. 1 Credit = (1977)$1 = (2024)$5.27 ... let's round to Cr 1 = $5 for simplicity.
@Carlobrand gave a price of Cr 1,500,000,000 (1.5 billion credits) for each 150 MT nuke ... that would be over $7.5 billion dollars per shot ($7,500,000,000)

[Potentially a price worth paying for a weapon that will eliminate a SOTA USN aircraft carrier task group with a single shot.]

Math is not my strong suit. I’m a criminology major

I think realistically the nuke would probably cost much much less than $7bn to make (especially with future sci-fi magic) but even at that price South Korea (currently number 9 on the global spending list) could buy six and still have 4billion USD to spend on my wages (the most important factor for Korean defence being retaining my wages as an English teacher rather than the hundreds of aircraft, vehicles, ships and 3.6m personnel.)

In all seriousness a weapon that powerful isn’t a bad shout as a planetary defence system, even at 7bn a pop. In theory the planetary defence budget of a moderately prosperous world should be able to absorb that and nukes are fairly low tech so it’s not like it’s difficult for a TL 10+ planet to make them (which iirc is why the Imperium deliberately restricts their use.)

If your enemy comes at you with a ship worth billions (which is most capital ships in Mongoose High Guard) it seems like a good trade.

 

[Tobias]

Striker gives 0.1 kt a penetration of 97 using the collapsing round table, and Striker's conversion translates an HG armor rating of 15 into a Striker armor rating of 85.

Collapsing rounds use the "other" column of the demolition table, being a sort of directed nuclear explosion. For a conventional nuclear warhead, I assume the standard column would be used.

MT doesn't have nukes that I know of, but their other weapons correlate pretty closely to their Striker counterparts, and they'd say an armor rating of 85 is a -15 DM, so amounts to the same.

It does have HG type nuclear missiles, but says nothing about yields etc.
Strangely, it does have an expanded full page version of the striker demolition table. What a strange thing to include in the basic rule set, at least in my eyes.

 

[Carlobrand]

Collapsing rounds use the "other" column of the demolition table, being a sort of directed nuclear explosion. For a conventional nuclear warhead, I assume the standard column would be used.
...

It didn't even occur to me to look at the demolition table. Thanks!

 

[Carlobrand]

So, coming back to PT boats in space, an IMTU thing oft-suggested by various parties, not sure who proposed it first:

Agility has no effect on missiles.

Logic is straightforward: missiles are closing with their target and, by the time they're in terminal phase and acting under their own sensors, they can adjust course as quickly as the target can change it. While some may debate the logic on various grounds, the effect is nonetheless positive.

First, PT boats, "fighters", with equal computer rating can now hit each other: they couldn't before, not unless you invoked some other fix. One of the more peculiar quirks of the game was seeing two lines of boats dance around each other, each utterly incapable of hitting their opposites. This fixes that.

Second, they can hit other targets. Not easily if there's a significant computer difference, and nukes aren't getting through any sort of damper if the computer difference is big enough, and heavy armor can still stop HE missiles, but they're more of a factor (especially if you also cap the damage table at 21 instead of 22). You'll see smaller, cheaper boats too since they die pretty easily to missiles and won't need as powerful a computer to do their work.

All in all, I definitely think it's worth doing.

 

[McPerth]

ogic is straightforward: missiles are closing with their target and, by the time they're in terminal phase and acting under their own sensors, they can adjust course as quickly as the target can change it.

That's as saying an airplane cannot dodge an AAM or SAM...

In LBB2 rules, if using the S3 for missiles, they are mostly useless, as they either are launched quite close or run out of fuel for maneuver while the ship can easily dodge them, as ahs unlimited (in combat terms) fuel to menuver itself

 

[chipla]

That's as saying an airplane cannot dodge an AAM or SAM...

I mean it’s harder for a plane to dodge an AAM than another plane using cannons right?

Maybe have a reduced ability to dodge based on whatever sensor/targeting/manoeuvre package the missile has?

Like the difference between 80’s tracking missiles and modern ones sort of thing.

 

[Tobias]

So, coming back to PT boats in space, an IMTU thing oft-suggested by various parties, not sure who proposed it first:

Agility has no effect on missiles.

Technically, this is a logical extension of the original missile rules: Maneuver/Evade programs have no effect on missiles. If they move into detonation range, you either shoot them down, disable them by ECM, or they hit you.

 

[kilemall]

That's as saying an airplane cannot dodge an AAM or SAM...

In LBB2 rules, if using the S3 for missiles, they are mostly useless, as they either are launched quite close or run out of fuel for maneuver while the ship can easily dodge them, as ahs unlimited (in combat terms) fuel to menuver itself

Hence errata interpreting missiles as per turn burn.

 

[whartung]

The thing that makes AAM difficult to dodge is that they're faster and can pull more Gs than the plane (or, at least, the occupant) can. The limitation is mostly having large enough fins to make the missile grab enough air to turn quickly enough (and not pull itself apart in the process). If the missile is closing from the front, they don't even necessarily have to be faster than the plane.

AAM missile maneuver is very cheap. A twitch of a servo, and the fins and air do the rest. In space, not so much.

Most vehicles have a large main drive, that is either on a gimbal, or it also has maneuver thrusters. The size of those thrusters discerns how responsive the missile is, and any thruster maneuver takes twice as much fuel since it has to accelerate the missile to start the maneuver, and decelerate the missile to stop it. The gimbal doesn't have that problem (I don't think, maybe it does).

Obviously missiles can be built with large range gimbals, or very large maneuver thrusters. They also benefit by not having to look anything like a missile, as there's no necessary need for streamlining. Four big motors up front, and one bigger motor in the back, wrapping a ticking time bomb.

Historically, in game, the missiles have only been "as fast" as the starship (at 6G potential). Mind, for many ships, 6G is a lot. 6G will eat up a free trader, but a DD is not a free trader. Arguably, a DD, while still having the same raw acceleration potential, it may not have the same nimbleness of a missile because it likely does not have over spec'd drives to facility actual maneuver (vs simply raw forward thrust potential).

Now, whether any of that matters at the scale of space combat is a different question.

At space ranges, I don't know if the missile can actually get within the reaction envelope of a large ship.

The notable thing about a missile is that it doesn't have to go that much faster than the ship. Unprotected, the ship is pretty much a dead duck. If the missile is going too fast (relatively), then it inherent reaction time to apply even its over spec'd delta V becomes a problem, reacting fast enough to maneuver, when up close. Thats where you need the target to be within the gimbal range of the ship, but you also need enough delta V capability in the drive to affect the velocity. So, having missile accelerate for long periods of time, is not necessarily a good idea. That's why you close with the ship before launching them, then the ship does the major maneuvering to match the target, not the missile. That's also why closing is a more difficult problem than chasing, the combined relative velocity can be very high.

One thing a missile can not do, is dodge a laser. There's no getting within that envelope. At 1000s of kilometers, you can't even blink faster than a laser can reach out and touch you. Ship lasers are designed hit other ships hundreds of thousands of kilometers away.

What's really missing, is the missile defense laser. 10,000 km range, high cycle rate, capable of firing amd tracking quickly. Able to handle several targets at once. Arguably, this is part of the reason behind the bomb pumped laser. To keep the missile out of the "instant kill" radius being very close to the ship, where the missile can't even get out of its own way, the laser is so fast -- even at 10,000km.

And at 10,000km, the missile doesn't bring much to the table save some fast moving shrapnel, which should not be disregarded. A cloud of fast moving shrapnel is an absolute danger. Less so than a solid piece, but not to be disregarded. Not as much of an issue in atmosphere, as they have the aerodynamics of metallic tree leaves, and the atmosphere drags the energy out of them. This does not happen in a vacuum.

Of course, a cloud of shrapnel at 10,000km can not maneuver, so if behooves the ship to do so to jink out of the way. But for Space Station Zebra -- that's a different problem, particularly if its not well armored.

 

[kilemall]

The thing that makes AAM difficult to dodge is that they're faster and can pull more Gs than the plane (or, at least, the occupant) can. The limitation is mostly having large enough fins to make the missile grab enough air to turn quickly enough (and not pull itself apart in the process). If the missile is closing from the front, they don't even necessarily have to be faster than the plane.

AAM missile maneuver is very cheap. A twitch of a servo, and the fins and air do the rest. In space, not so much.

Most vehicles have a large main drive, that is either on a gimbal, or it also has maneuver thrusters. The size of those thrusters discerns how responsive the missile is, and any thruster maneuver takes twice as much fuel since it has to accelerate the missile to start the maneuver, and decelerate the missile to stop it. The gimbal doesn't have that problem (I don't think, maybe it does).

Obviously missiles can be built with large range gimbals, or very large maneuver thrusters. They also benefit by not having to look anything like a missile, as there's no necessary need for streamlining. Four big motors up front, and one bigger motor in the back, wrapping a ticking time bomb.

Historically, in game, the missiles have only been "as fast" as the starship (at 6G potential). Mind, for many ships, 6G is a lot. 6G will eat up a free trader, but a DD is not a free trader. Arguably, a DD, while still having the same raw acceleration potential, it may not have the same nimbleness of a missile because it likely does not have over spec'd drives to facility actual maneuver (vs simply raw forward thrust potential).

Now, whether any of that matters at the scale of space combat is a different question.

At space ranges, I don't know if the missile can actually get within the reaction envelope of a large ship.

The notable thing about a missile is that it doesn't have to go that much faster than the ship. Unprotected, the ship is pretty much a dead duck. If the missile is going too fast (relatively), then it inherent reaction time to apply even its over spec'd delta V becomes a problem, reacting fast enough to maneuver, when up close. Thats where you need the target to be within the gimbal range of the ship, but you also need enough delta V capability in the drive to affect the velocity. So, having missile accelerate for long periods of time, is not necessarily a good idea. That's why you close with the ship before launching them, then the ship does the major maneuvering to match the target, not the missile. That's also why closing is a more difficult problem than chasing, the combined relative velocity can be very high.

One thing a missile can not do, is dodge a laser. There's no getting within that envelope. At 1000s of kilometers, you can't even blink faster than a laser can reach out and touch you. Ship lasers are designed hit other ships hundreds of thousands of kilometers away.

What's really missing, is the missile defense laser. 10,000 km range, high cycle rate, capable of firing amd tracking quickly. Able to handle several targets at once. Arguably, this is part of the reason behind the bomb pumped laser. To keep the missile out of the "instant kill" radius being very close to the ship, where the missile can't even get out of its own way, the laser is so fast -- even at 10,000km.

And at 10,000km, the missile doesn't bring much to the table save some fast moving shrapnel, which should not be disregarded. A cloud of fast moving shrapnel is an absolute danger. Less so than a solid piece, but not to be disregarded. Not as much of an issue in atmosphere, as they have the aerodynamics of metallic tree leaves, and the atmosphere drags the energy out of them. This does not happen in a vacuum.

Of course, a cloud of shrapnel at 10,000km can not maneuver, so if behooves the ship to do so to jink out of the way. But for Space Station Zebra -- that's a different problem, particularly if its not well armored.

I always figured the PD shot in LBB2 was a low power high cycle shot at incoming. In fact it was the laser rules that got me thinking 100 second action sub turns/power allocation- main fire is 500s, return fire is 400s, PD shot is 100s.

Going to LBB5, return fire pretty much has to be discarded. So I went to 100s/base 10000 km or 10s/base 1000km options, assuming all lasers can do that. The limitation is cooling, so once a laser fires a full antiship 100000 km plus shot it can’t switch to PD work for 1000s, or risk damage.

For the thrifty merch starship, I offer cheaper lasers tuned only to one range/fire rate rather then all three.

Big problem, even if you go with one of those Striker PD pulse lasers, those missiles are hustling in darn fast, probably only have a few seconds before it gets into fragmentation/HEAT range.

If you are getting into those weeds, don’t forget your special PD friend the VRF gauss gun, or the mass drivers.

 

[Carlobrand]

That's as saying an airplane cannot dodge an AAM or SAM...

In LBB2 rules, if using the S3 for missiles, they are mostly useless, as they either are launched quite close or run out of fuel for maneuver while the ship can easily dodge them, as ahs unlimited (in combat terms) fuel to menuver itself

What they said.

Seriously though, there's a world of difference between maneuver in air and maneuver in vacuum, and there's a world of difference between turn based maneuver on a hex map and a simulated intercept in a program. If the missile's on target, and the target alters its vector, then the missile should still connect if it has enough thrust to adjust its own vector. Might be sideways on impact, not sure if that'd be a problem. Maybe I'm missing something.

 

[Jame]

I read in David Drake's RCN series that once a missile is moving fast enough-say, at Traveller speeds-the kinetic impact will be powerful enough to do damage on its own that a nuke wouldn't add enough of an effect to be worth the money.
So, the nuke warhead rating could just be taken as kinetic force.

 

[chipla]

I read in David Drake's RCN series that once a missile is moving fast enough-say, at Traveller speeds-the kinetic impact will be powerful enough to do damage on its own that a nuke wouldn't add enough of an effect to be worth the money.
So, the nuke warhead rating could just be taken as kinetic force.

In MgT2e (I.e the edition I have in front of me) the standard missile does 4d6 dmg while the nuke does 1DD or 1d6x10 dmg which is a fairly significant increase in damage for it all to be purely kinetic (also the nuke has the radiation trait).

I agree that probably realistically at the sort of velocities I’d imagine are involved in space combat you’re probably gonna get more damage from kinetic impact than explosions (especially since I feel like the pressure effects and thermal effects aren’t exactly gonna be spreading through the vacuum in the same way the do in atmosphere) but in game terms in Traveller there’s a good reason to use nukes if you can afford them/aren’t gonna have someone hunt you for using them.

 

[Dragoner]

In my setting nukes are casaba howitzers https://en.wikipedia.org/wiki/Casaba-Howitzer making a city buster will get everyone to immediately attack.

 

[kilemall]

What they said.

Seriously though, there's a world of difference between maneuver in air and maneuver in vacuum, and there's a world of difference between turn based maneuver on a hex map and a simulated intercept in a program. If the missile's on target, and the target alters its vector, then the missile should still connect if it has enough thrust to adjust its own vector. Might be sideways on impact, not sure if that'd be a problem. Maybe I'm missing something.

If I understand the missile supplement plus clues in Striker, the missiles are firing HEAT or HEAP in their nomenclature. As such the missiles would orient prior to detonation and send its cloud of hyper accelerated plasma towards the expected intercept point. So the shots could be off center of the missile flight path.

 

[Carlobrand]

I read in David Drake's RCN series that once a missile is moving fast enough-say, at Traveller speeds-the kinetic impact will be powerful enough to do damage on its own that a nuke wouldn't add enough of an effect to be worth the money.
So, the nuke warhead rating could just be taken as kinetic force.

I don' t worry much about what a KK missile does on impact. I worry about what it does after it has impacted, has punched through the intervening armor, and is inside and trying to punch its way through the armor on the other side.

 

[Condottiere]

I think it was Fire Fusion Steel that clarified that what we wanted was a penetrator rod.

 

[Rupert]

I read in David Drake's RCN series that once a missile is moving fast enough-say, at Traveller speeds-the kinetic impact will be powerful enough to do damage on its own that a nuke wouldn't add enough of an effect to be worth the money.
So, the nuke warhead rating could just be taken as kinetic force.

At about 3 km/s, an object's kinetic energy is the same as the chemical energy an equal mass of chemical explosives would have. Thus above that point there's little increase in damage to be had from explosive warheads (just put any spare mass into fuel to get a higher terminal velocity).

One G for 1,000 seconds get you 10 km/s, for about ten times the energy of this threshold

Nukes are enormously more powerful, especially in terms of bang per kilogram. One that'll fit onto a standard CT missile will be quite weak, say 1 kiloton, because most of its mass will be non-nuclear control systems, chemical initiators, and so on. But even 1 kT for a 0.1 ton missile means the missile needs to be going about 300 km/s to have the same energy density from kinetic energy (five 1,000s turns at 6G), and a nuke brings a stand-off capability as well - no need to get an actual contact hit.

So nukes are very definitely worth it as long as dampers aren't all-powerful. They make hits easier and bring a huge increase in damage potential.