Drop Tanks

[Badenov]

I have recently come to the conclusion that drop tanks are, or should be, ubiquitous on military ships (and pirates).

Tactically, they allow you to jump back, if you jump into an ambush, or to retreat from a system without the need to refuel. That tactical flex is the difference between losing two weeks and losing the ship. Why would you spend megacredits on a ship that could get stranded someplace, and pinned down by a superior force? I think technically you could Jump out of combat if you're outside 100 diameters? And if you misjump, you still have a full tank of gas to try and get someplace. This can also give you the tactical flex to jump into empty hexes, but you'll need more power plant fuel to make that work.

Have I analyzed the situation incorrectly? Why do all military ships not have drop tanks?

 

[Condottiere]

Drop tanks are incredibly fragile.

For strategic movement, sure.

But you have to remember, that the jump drives have to be scaled up for that to take effect, and not all starwarships are worth it.

 

[Badenov]

Drop tanks are incredibly fragile.

For strategic movement, sure.

But you have to remember, that the jump drives have to be scaled up for that to take effect, and not all starwarships are worth it.

How do Jump Drives have to scale up?

 

[mike wightman]

I agree.
There are several ways to achieve strategic mobility.
Move your battle riders and battleships around by high jump tender.
Use drop tanks up on every jump.

To have maximum strategic and tactical utility I like to stick a jump 1 engine and enough fuel for a jump 2 in addition to pp fuel.

The reason for this is if you only have fuel for jump 1 and take a fuel hit you are stuck.

Any jump into a system should be via drop tanks or a tender drops you off.

 

[whartung]

You can also simply not jump in tanks dry, leaving J1 in reserve. There's nothing that says you need to go back where you came from. Even jumping into an empty hex tanks dry is better than having the element reduces to floating space debris. It's not like the enemy is likely to hunt you down, and any fleet of size will have ships that can get a message home to relay "We're at XYZ123 -- send tankers!".

If you're going to haul that volume through jump space, may as well put it into the ship and get an extra hardpoint or two out of it.

Put J4 of fuel on your J3 ship.

Drop tanks need infrastructure, whereas most penetration raids rely on wilderness refueling (or tankers which need wilderness refueling).

The drop tanks are only their for the first jump, not for the campaign.

Strategic surprise is pretty difficult. Intelligence is ship heavy, but mostly cheap to get. Just ("just") send out a bunch of scouts flitting in and out of the systems of interest to try and get a handle on where (more importantly, when) the enemy fleets are in system.

I think it would be rare for a fleet to jump in and be surprised by a large force. They should have some vague idea that the fleet would be there in the first place when they jumped in.

The goal is to jump to places that don't have fleets (making for easy raiding), or if you are going to jump into a enemy fleet, the goal is to reduce that fleet anyway, so less of a surprise, and go in with a dominating force.

War is war, intelligence is imperfect, but it's simply pretty hard to "hide" fleets of any real size.

In the end, I don't think the need for a emergency out comes up that often to be worthwhile designing the fleet around it.

But ya never know!

 

[Dragoner]

Have I analyzed the situation incorrectly? Why do all military ships not have drop tanks?

I have them on everything in my TU, though I will add from looking at descriptions, is that all pumps are in tank, for ullage, and pushing.

 

[McPerth]

t's not like the enemy is likely to hunt you down,

That will depend onm another unaswered question: can the destiantion of a jumping ship be determied by seeing it jumping?

If so, the enemy may well chase you if they know your destination. If he has enough superiority (and I assume so if you fleed the system), it may be worth for him to destoy your TF

See this old thread where this was discussed.

 

[Condottiere]

They're usually three levels:

1. Strategic - which usually means that infrastructure and support was prepared, usually at domain and sector commands.

2. Operational - sector command placing it's assets where they want them to be.

3. Tactical - jumping in, and looking around, deciding if it's worthwhile staying.

At the tactical and operational levels, the enemy may decide to destroy the infrastructure that supports large scale utilization of drop tanks; hence, you might want to take them along with you.

 

[mike wightman]

If I were running the IN and had to defend the SM I would have deep space bases with fuel, spares, replacement crew, and drop tanks within jump 1 of every major world.
Every IN base would have a deep space cache like this.

 

[whartung]

That will depend onm another unaswered question: can the destiantion of a jumping ship be determied by seeing it jumping?

JTAS 24

Microjumps can also confuse an observer or enemy. Because a ship's jump destination cannot be predicted, a microjump within a system still leaves an impression that the ship has left; a week later, it emerges from jump in the same system, to the observer's confusion.

Answered well enough for me.

 

[Condottiere]

Assuming you can measure the energy output of the jump drive, you might come to the conclusion the exit point is within four light years.

 

[Badenov]

The operation may go like this:
1. Arrive in system
2. Decide to retreat or stay.
3. If stay, do your thing. If retreat, jump back home or alternate destination.
4. If you stayed, when you are ready to jump out, full your drop tanks from your internal jump fuel tanks.
5. Jettison filled drop tanks.
6. Refuel normally at Gas Giant/planetary ocean if no refuelling station exists.
7. Return to and reattach drop tanks.
8. Jump with drop tanks.
9. The fuel that was recently scooped can be processed during the week you're in jump, so it's processed and you're ready to restart at step 1.

 

[Carlobrand]

Drop tanks are pretty much essential for an initial assault, but they can slow your advance if you depend too much on them, which can give the enemy time to prepare for you.

 

[Carlobrand]

If I were running the IN and had to defend the SM I would have deep space bases with fuel, spares, replacement crew, and drop tanks within jump 1 of every major world.
Every IN base would have a deep space cache like this.

Pretty much the only way a Navy base survives outside of a fortress world is if it's designed to jump key resources to the outer system if a superior force appears.

 

[Dragoner]

Head canon for me was that the depots housed big constructor fleets with automated factories like from TTA, so that one could simply set up shop anywhere.

 

[warwizard]

OK how well drop tanks work depends on which ruleset yout TU designs the ships with.
T4 FF&S: 1) Jump drives required to have built at TL 15+. They do NOT have to be max jump drives, a TL 15 drive at J1 can use drop tanks.
2) Drop tanks can be made at any A or B port, however this means the materials used will vary, which makes the fuel carried in a 10DT drop tank inconsistant depending on construction materials used.
3) Drop tanks are to be armored to the same standard as the ship they are mounted on.
4) You may procure comformal tanks that maintain the ship's streamlining, but are limited to 20% of the hull displacement.

 

[Badenov]

OK how well drop tanks work depends on which ruleset yout TU designs the ships with.
T4 FF&S: 1) Jump drives required to have built at TL 15+. They do NOT have to be max jump drives, a TL 15 drive at J1 can use drop tanks.
2) Drop tanks can be made at any A or B port, however this means the materials used will vary, which makes the fuel carried in a 10DT drop tank inconsistant depending on construction materials used.
3) Drop tanks are to be armored to the same standard as the ship they are mounted on.
4) You may procure comformal tanks that maintain the ship's streamlining, but are limited to 20% of the hull displacement.

That's quite different than the ruleset I have (Mongoose 2008).
Question 1: how does the construction material change the fuel you put in a tank? Really the only way to get hydrogen to sufficient density is liquid hydrogen. It is somehow assumed that the process of skimming from a gas giant or body of water automagically makes this conversion before the fuel is stored, but I suppose it explains the time requirement of 1-6 hours as part of that being the processing.
Question 2: how do you armor a drop tank?
Comformal drop tanks would be super useful and let you skim fuel or whatever. The 20% limitation would be a big limit, though.

 

[Rupert]

FF&S required a certain amount of armour and internal structure, and how much volume that required varied with the TL of the materials used to make the tank. Thus a 10DT tank would hold less than 10DT of hydrogen, and the exact amount would vary with the TL of manufacture.

 

[Badenov]

Ahhhhh

 

[AnotherDilbert]

I have recently come to the conclusion that drop tanks are, or should be, ubiquitous on military ships (and pirates).

Tactically, they allow you to jump back, if you jump into an ambush, or to retreat from a system without the need to refuel. That tactical flex is the difference between losing two weeks and losing the ship. Why would you spend megacredits on a ship that could get stranded someplace, and pinned down by a superior force? I think technically you could Jump out of combat if you're outside 100 diameters? And if you misjump, you still have a full tank of gas to try and get someplace. This can also give you the tactical flex to jump into empty hexes, but you'll need more power plant fuel to make that work.

Have I analyzed the situation incorrectly? Why do all military ships not have drop tanks?

Yes, they are a nice extra, but you can't rely on them... Once used, they are gone. It becomes a logistical nightmare.

If you can't reliably manufacture them at the frontline (in your own territory) you have to ship them from your own shipyards to your fleets, requiring extra resources (tankers & transports).

But for initial movement, or prepared assaults, sure they're great.


You can add them to ships after construction, so it's no big deal if the ship has them from the start.