Drop Tanks and Breakaway hulls: The Lesser Evil

[PsiTraveller]

Cute pun on Lesser Evil aside, I have been playing around with making a breakaway ship that acts as a battle rider section. The Jump Drive and fuel tank have the Breakaway collar and before battle the sections would break into two ships. A saucer section for battle, and the Jump engines and fuel tank (picture a central body and two nacelles for Jump engines)


Seriously though, I realized that the ship short changes itself, and that any design that involves removing the fuel tank before battle has tactical issues that need to be considered. After looking at the discussions about keeping a Drop Tank on during jump, or removing a tank for combat I tried to make one.

Going back to my 1000 ton hull from my other posts a J4 capacity would involve 100 tons of Jump engine and 400 tons of fuel, plus a cockpit, computer, M-Drive and Power Plant. Add in a couple of staterooms for the pilot and engineer you would need and you have about 550- 600 tons of ship leaving. This leaves you with 400 tons of 'combat ship'. This just makes the ship a smaller spaceship not a starship.

The speed advantage would be a savings on M-Drive cost at 2 MCr per ton, but then you need to buy a second power plant to power the Breakaway section of hull. It could be small, and rely on main power plant to provide Jump power. This would help by having the larger Power Plant on the battle section, all the extra power would reduce the impact of an Ion attack.

The tactical loss under Traveller design rules is that you lose 6 hardpoints. The hardpoints would go with the Jump section of the 2nd ship, This reduces your PD capacity, offensive throw weight and turns your 1000 ton attack ship into a 400 ton SDB with a big engine. Your fuel tank section would actually have more weapons than your battle section since it has more tonnage.

1000 tons is a low end, and the math gets a little better with increased tonnage, the Jump engines run 10 percent of hull and fuel is 10 percent times J4 range.

You could keep your Jump engine on the battle section just to keep the hardpoint. This increases your hardpoints, but puts your Jump Drive at risk.

You are looking at reducing your tonnage and thus hardpoints by at least 40 percent, probably close to 50 to account for Power Plant, M-Drive and crew for the breakaway section. This is a problem if you were hoping to make a breakaway ship that split.

The same issue is there for the removable fuel tank even if it is not a breakaway hull but is just a removable demountable tank. The loss of 40 percent of your tonnage means that you lose 40 percent of your hardpoints.

Larger ships may have some more room to add extra weapons because the crew needs are not as tight. you have room for larger bays etc and do not have to worry about the 400 ton limit. The 40 percent of space for fuel does not change.

So once again I am looking at the Drop Tank ship that needs to be supplied with a Drop Tank to leave a system. The extra 40 percent of space is very attractive for weaponry.

Anyone else run into similar problems or issues with a removable fuel tank design?

 

[phavoc]

A pure battlerider that is not burdened by having to carry around the jump drive will always win this concept battle. As you pointed out, it's somewhat a philosophical one, as your ship, IF it can get to it's drop tanks, can jump itself away from the system.

But take a step back and compare it's mission to that of a rider - both are looking to shed the tonnage required for jump fuel and go with as pure weapons and defenses load as possible. Both suffer from the loss of hard points without accommodating the internal tonnage for a drop tank. It's probably a wash for the clamps. The rider could, arguably, cheat and push that tonnage onto the carrier craft.

An advantage of the carrier craft is that (a) it's mobile, (b) it can be armed. Your lonely drop tanks cannot, and they are quite vulnerable to any sort of damage that would destroy them.

Your breakaway craft is similar to the rider concept. I'm not sure it's any better, as it essentially becomes a rider carrier. I'm not sure that having the ships come together in combat makes much of a difference vs. having a rider and a carrier. The time to mate the sections should be equivalent to the time it takes for a rider to dock, and they should both suffer the same penalties as far as engaging/dodging an enemy. Plus your breakaway ships would also need to hook up to your external tank. If an enemy was pursuing you it's possible your tank could get hit, or even destroyed, prior to your jumping. You wouldn't have the same vulnerability with a pure carrier/rider concept.

Plus, lets not have Voltron in Space, eh? Breakaway hulls sound cool, but the tried and true designs will probably provide the most versatility with the least risk. Breakaway combat ships should be built for specific missions, so maybe they belong more in a spec-ops role rather than front-line units. I don't suspect any planetary navies are going to waste the money on them, as most systems are going to be credit-strapped to deploy a decent naval force - fortunately for them the majority won't need jump drives, so they can save both tonnage and credits.

 

[PsiTraveller]

Drop Tanks provide a ship with the same hardpoints and extra space. I think some good designs could be made on that model. I know we've discussed the lack of return trip, and it may be that a stealth ship with intent to cause maximum damage behind the lines is the design I will end up with. I am not done playing around with the ideas yet.

I am also trying to figure out what cargo ship could jump in with a fleet carrying return tanks. It may be heavily robotic (with Virus repercussions for those of us who played TNE) in order to save space for internal fuel. Staterooms replaced by fuel storage capacity.

 

[Chas]

Yep, your breakaway hull is not a combat optimized design and never will be, it will always lose out cost-wise to a true carrier or traditional cruiser. I've been struggling myself, apart from the example posted in the Cruisers thread, to find other uses for them that aren't heading off into rules abuse territory like AnotherDilbert posted.

As for going back to your drop tanks thinking to use them after battle or whatever as a feasible plan this is not going to fly unless you've left them in another solar system. The designs I do with drop tanks are specifically made on the concept you will lose your drop tanks if you ever have to face combat, and highly risky in any event. I certainly don't see them as a rules abuse - you are gambling with a 1000MCr vessel and they just aren't going to be common functionality, they aren't replacing standard designs, just offering specific advantages which you have fair trade offs for and against. The build like the 2+2 I've done in the Hades cruiser example is good representation of how drop tanks can assist a strike cruiser... but it is very specifically a strike cruiser, it is not a cruising cruiser and would see limited use. The 3+1 example AnotherDilbert put up might be more common. But again, you need to weigh the pros and cons and let's remember this is high TL. The lower TLs don't get to play this game so effectively - which to be honest I'm reasonably pleased about the way the rules are tilted, I only see this as some justifiable advantage that high TL gets.

 

[phavoc]

Yep, your breakaway hull is not a combat optimized design and never will be, it will always lose out cost-wise to a true carrier or traditional cruiser. I've been struggling myself, apart from the example posted in the Cruisers thread, to find other uses for them that aren't heading off into rules abuse territory like AnotherDilbert posted.

As for going back to your drop tanks thinking to use them after battle or whatever as a feasible plan this is not going to fly unless you've left them in another solar system. The designs I do with drop tanks are specifically made on the concept you will lose your drop tanks if you ever have to face combat, and highly risky in any event. I certainly don't see them as a rules abuse - you are gambling with a 1000MCr vessel and they just aren't going to be common functionality, they aren't replacing standard designs, just offering specific advantages which you have fair trade offs for and against. The build like the 2+2 I've done in the Hades cruiser example is good representation of how drop tanks can assist a strike cruiser... but it is very specifically a strike cruiser, it is not a cruising cruiser and would see limited use. The 3+1 example AnotherDilbert put up might be more common. But again, you need to weigh the pros and cons and let's remember this is high TL. The lower TLs don't get to play this game so effectively - which to be honest I'm reasonably pleased about the way the rules are tilted, I only see this as some justifiable advantage that high TL gets.

Actually, if you can get into a system without being intially spotted, and especially if you above/below the plane of the elliptic, you can drop them off in space and the odds of someone finding them are pretty small. They won't give off any signature as they have no power source. But operationally... I still don't see a first-rate navy deploying mainline combatants with this idea. Far too easy for something bad to happen to them. And as I've said, you get a middling rider out of the concept. Not the best of either world really.

 

[Chas]

As I understand it the jump signature incoming is pretty much highly likely to be always spotted unless you have a stealth jump which ships of the line won't have. Or perhaps not?

 

[Condottiere]

If you can base total number of hardpoints on drop tanks, the rules may need to be revised that hardpoints be based on actual surface area.

 

[AnotherDilbert]

If you can base total number of hardpoints on drop tanks, the rules may need to be revised that hardpoints be based on actual surface area.

No. The drop tanks are clearly (I hope?) outside the hull, not part of the hull, just as external cargo.

 

[AnotherDilbert]

As I understand it the jump signature incoming is pretty much highly likely to be always spotted unless you have a stealth jump which ships of the line won't have. Or perhaps not?

That is my understanding too.

Normally, a ship that emerges into real space will be automatically detected if it emerges within the ‘minimal’ detail range of the sensor.

Note that we do not have any specification for sensor performance at Very Distant and Far range, but we might assume that any sensor that has Minimal detail at Distant, also has that at longer ranges.

Far: (over 5,000,000 km): At these ranges, sensors can spot the signature of ships making jumps...

Stealth advantage for a J-4 jump drive is about as expensive as an Emissions Absorption Grid, cheaper than Stealth. A stealth ship should probably have a stealth jump drive, otherwise anyone knows you jumped into a system.

 

[AnotherDilbert]

Actually, if you can get into a system without being intially spotted, ...

Without being spotted requires stealth jump drives and practically distance to any advanced sensor system of over 5 million km. Without stealth jump drives any sensors, even civilian, in the system will see you jump in.

... and especially if you above/below the plane of the elliptic, you can drop them off in space and the odds of someone finding them are pretty small. They won't give off any signature as they have no power source.

Um, any passive object in direct sunlight will be warmer than the cosmic background. Drop tanks can't be stealthed. By RAW I think there is a very good chance of detection by any advanced sensor system within 5 million km, or even beyond that. You'll probably have a better chance of hiding among other objects in space such as an asteroid belt, ring system, Oort cloud, or something.

But operationally... I still don't see a first-rate navy deploying mainline combatants with this idea. Far too easy for something bad to happen to them. And as I've said, you get a middling rider out of the concept. Not the best of either world really.

I tend to agree. I prefer to build combatants that does not rely on drop tanks, but uses them to enhance performance. Others disagree. The risk is theirs to take.

 

[phavoc]

Space in a system is vast. So what if you need to drop into space a few million more klicks away from your target. The difference is, at most, a few hours transit time. And you will save a ton of money on not paying for a stealth drive. And now that every ship is getting 9G drives (military ones at least), the time differential for transiting far enough way your jump flash isn't detected is trivial.

Objects in space certainly CAN absorb heat, but that all depends on the distance from the primary/secondary star AND the type of star AND the surface of the object. As we know from our own solar systems, we've got many objects floating around that are in direct sunlight and yet they do not reflect heat. These objects being floating rocks, some in our same orbit even that we almost run into. And they are only spotted on radar, NOT thermal. I suppose visual is a cue, IF you get lucky enough to be looking at the right place and the right time.

I tend to agree. I prefer to build combatants that does not rely on drop tanks, but uses them to enhance performance. Others disagree. The risk is theirs to take.

We are debating the overall technology and it's efficacy. Traveller has a long history of letting players design their ships however they so choose (and players love to min/max unrealistic designs).

We are trying to establish the baseline technology here. And from there we establish canon/standard designs. What individual players do is one thing, but when it's being proposed for wholesale application to everything, then you have to look at the standard you are trying to establish and ensure the foundation makes sense and fits within the settings. ADDING to it, by a group of players, is a time-honored tradition and should be continued. I just want to make sure the standards we are going to build upon and see canonical designs based upon fall within the guidelines of common-sense and stick, more or less, to the past. I love to see incremental improvements, but sometimes, thinks like the collectors, are wholesale changes to the entire game system and it's very rich history. If I wanted wholesale changes I might as well go out and buy Star Wars or some other SciFi game system. It actually does mean something, to me at least, when you say Traveller, the gaming system. I do have a lot of expectations to tie the current one to the older ones.

 

[AnotherDilbert]

Space in a system is vast. So what if you need to drop into space a few million more klicks away from your target. The difference is, at most, a few hours transit time. And you will save a ton of money on not paying for a stealth drive. And now that every ship is getting 9G drives (military ones at least), the time differential for transiting far enough way your jump flash isn't detected is trivial.

Not being spotted requires Stealth Jump drive AND distance. Agree that the distance is no big deal.

 

[AnotherDilbert]

Objects in space certainly CAN absorb heat, but that all depends on the distance from the primary/secondary star AND the type of star AND the surface of the object. As we know from our own solar systems, we've got many objects floating around that are in direct sunlight and yet they do not reflect heat. These objects being floating rocks, some in our same orbit even that we almost run into. And they are only spotted on radar, NOT thermal. I suppose visual is a cue, IF you get lucky enough to be looking at the right place and the right time.

If we take a random rock (Ceres) surface temperature seems to be about -100 °C, much warmer than cosmic background. I'm assuming 3000-year-into-the-future sensitive thermal sensors...

 

[phavoc]

Objects in space certainly CAN absorb heat, but that all depends on the distance from the primary/secondary star AND the type of star AND the surface of the object. As we know from our own solar systems, we've got many objects floating around that are in direct sunlight and yet they do not reflect heat. These objects being floating rocks, some in our same orbit even that we almost run into. And they are only spotted on radar, NOT thermal. I suppose visual is a cue, IF you get lucky enough to be looking at the right place and the right time.

If we take a random rock (Ceres) surface temperature seems to be about -100 °C, much warmer than cosmic background. I'm assuming 3000-year-into-the-future sensitive thermal sensors...

I was referring to the rock that Earth almost hit a few months ago. It was coming in from the sun-side and it paralleled Earth's orbit for a bit. Since our orbital speed was a bit faster we almost ran it over. And we had no idea it was there till we were bearing down upon it.