Gas Giant Skimming

[Timerover51]

Even adding more asteroid sized bodies into close orbits of the gas giant should be possible. Lots of rocks racing around it will complicate navigation and maneuver in and out of the gas giant. I doubt getting hit by 10,000 tons of rock at thousands of KM a minute would be good for any ship.

Have you consider exactly how many rocks would be needed to pose a danger to ships using skimming, and what the energy requirements would be of moving them there and placing them in close orbit?

Two additional questions.

How long does a System Defense Boat stay in a gas giant's atmosphere before it has to return to its base, wherever that may be?

How many System Defense Boats would be required to cover either Jupiter or Saturn?

 

[McPerth]

Have you consider exactly how many rocks would be needed to pose a danger to ships using skimming, and what the energy requirements would be of moving them there and placing them in close orbit?

(...)

How many System Defense Boats would be required to cover either Jupiter or Saturn?

Some sources tell that the skimming is usually done in the poles due to the effect of the onw Gas Giant emited radiation. If so, you must mainly cover the poles, so vastly reducing the needed SDBs to cover the refuelling ops.

Of course, this does not answer your questions, but may give some clue to help...

Two additional questions.

How long does a System Defense Boat stay in a gas giant's atmosphere before it has to return to its base, wherever that may be?

AFAIK, this is not clearly answered in canon, but my guess is that until they need routine maintenance. Fuell will not be a problema (they are in a fuel source, after all), and crews may be kept in low berths (or fast drug) until needed.

Of course, this is (again) subject to how safe are low berths in the version you're using...

 

[coliver988]

Gas giants are pretty big

Found the image for comparing a GG to Earth. There is a LOT of volume to both hide in and gas skim. Cat and mouse shenanigans possibly.

Source: https://i1.wp.com/mossandfog.com/wp...rth-size-comparison.jpg?resize=1200,651&ssl=1

 

[whulorigan]

Since wilderness refueling behind enemy lines is mission requirement, you'd like to think that the fleet is prepared to deal with the specifics of beating of SDBs occluded in the atmosphere.

The attacking fleet is not going to "delay". You have to appreciate that they're not going to wait. There's nothing to wait for. The longer they stay, the more dangerous it becomes. No help is coming, and I doubt the SDB crews are going to get bored. The attackers really have nowhere to go, and are backed in to a corner the moment they arrive. They're dead already, and motivated to fight it out.

So, they will start refueling and destroy anything that gets in their way. If they take damage, then, hey, C'est la guerre. They knew this going in to it. No doubt the planners took it in to consideration when they planned the raid.

The only surprise is if the SDB forces awaiting the fleet are notably larger than whatever intelligence was reporting to be expected.

Even with any potential advantage of being in the atmosphere, I do not believe that SDBs can dramatically outfight their weight beyond the advantage of extra tonnage in lieu of a jump drive (assuming they are, indeed, just space ships vs star ships). The atmosphere works both ways, and will disadvantage both parties (though it may affect the attacker more than the SDB). The worst case is SDB blindly salvoing missiles out of the atmosphere to autonomously seek orbital targets once clear of the interference. You also have the case that when the refueling ship may simply bury itself in the atmosphere while refueling, offering it the same defensive advantages the SDB have. They simply have to survive the interface portions going in and going out.

And it does not discount the spreading of forces necessary to cover the different gas giants for systems with more than one. Theses defenses are very expensive. It can easily be decided that they are not worth defending, vs investing the defense on actual targets and infrastructure.

Seems to me that the way to deal with SDB's hidden in GG atmospheres is to use densitometers and/or neutrino sensors triangulating from several separate vessels to detect power plant emissions - no neutrino emissions should be coming from within the GG itself.

The ideal weapon to use against the SDBs would be Meson Bays - they are not affected by the atmosphere, and do not necessarily even need to directly hit, as their energy release within the atmosphere would have an effect similar to depth charges against a submarine.

 

[Carlobrand]

SDBs are a known quantity. An opposing fleet can predict about how many there will be and about how powerful they are, based on the tech level and wealth of the system that fields them. They can often be avoided - many systems can't field SDBs. One presumes systems that can field SDBs also have reasonable planetary defenses, or an attacker on detecting neutrinos would simply vector for the mainworld and leave the SDBs to choose between chasing them and engaging them without benefit of a gas giant to hide in or seeing them force a refueling at the mainworld under threat of bombardment.

So a hostile force arrives. It's there either because it has no other choice or because it wants to be there and is confident it can deal with the SDBs. If it's there because it had no other choice, the SDBs may be a substantial threat; it may opt to try a refueling under fire so it can jump out quick, rather than stay and fight it out. If it's there because it's confident it can deal with the SDBs, then what happens next depends on its long-term plans. It stays and bombards if it has the time, and the SDBs can rise to fight or make the fleet spend time killing them slowly in the depths, or if it's in a hurry it goes in to refuel and gives the SDBs a choice: die while contesting the refueling or let them refuel.

 

[BRJN]

I can see a merchant skimming from a GG if the main world is a satellite thereof, and cash-in-hand is an issue.
If the GG and main world are in separate orbits, travel time becomes prohibitive. If you are travelling a route which has non-cash-generating stops (ex: ISW-era Sirius) then driving across the system to save on a tank of gas is being penny-wise but pound-foolish.

 

[whartung]

SDBs are a known quantity.

This is essentially my thesis. SDBs can be considered a fixed position, rather than a dynamic element (such as stumbling upon an enemy fleet that wasn't supposed to be there).

Obviously, unlike costal defense guns, SDBs can more readily be moved either from one GG to another, or even to another system. Fun with the intelligence services.

Simply they're a (more than not) static defense that the planners can take in to account in plotting the mission.

In the end, they have some efficacy. Ideally, TL for TL, equal tonnage is equal effectiveness. Writ large, 2 10KdTon battle cruisers should have a 50/50 chance of taking the battle.

Perhaps the SDB's effectiveness and advantage gives them a 5:1 benefit. Do folks think that a 1000 ton SDB would be a match for a 5000 ton warship, both intent on hunting each other down? There's no reason for the ships to get locked in to fueling before they swept the area for SDBs.

10:1?

In theory, they're "worth it", otherwise we wouldn't have heard so much about them. The navies build them for a reason, and corruption, graft, and politics can't explain all naval expenditures, so they must be worth something to someone.

So, it would be more interesting to have this more fleshed out as to how SDBs fight, how they kill ships, and how to kill them back.

If I send 10 10Kton cruisers on a deep penetration raid, where they have to sweep 4 enemy gas giants to get to their target, how many will get there?

 

[Silverhawk]

This is essentially my thesis. SDBs can be considered a fixed position, rather than a dynamic element (such as stumbling upon an enemy fleet that wasn't supposed to be there).

Obviously, unlike costal defense guns, SDBs can more readily be moved either from one GG to another, or even to another system. Fun with the intelligence services.

Simply they're a (more than not) static defense that the planners can take in to account in plotting the mission.

In the end, they have some efficacy. Ideally, TL for TL, equal tonnage is equal effectiveness. Writ large, 2 10KdTon battle cruisers should have a 50/50 chance of taking the battle.

Perhaps the SDB's effectiveness and advantage gives them a 5:1 benefit. Do folks think that a 1000 ton SDB would be a match for a 5000 ton warship, both intent on hunting each other down? There's no reason for the ships to get locked in to fueling before they swept the area for SDBs.

10:1?

In theory, they're "worth it", otherwise we wouldn't have heard so much about them. The navies build them for a reason, and corruption, graft, and politics can't explain all naval expenditures, so they must be worth something to someone.

So, it would be more interesting to have this more fleshed out as to how SDBs fight, how they kill ships, and how to kill them back.

If I send 10 10Kton cruisers on a deep penetration raid, where they have to sweep 4 enemy gas giants to get to their target, how many will get there?

It is a fair question. I still think that a system that knows or is known to be a potential target for either a raid or refueling spot for raiders trying to hit other systems should have other defensive 'works' to attrit the enemy's strength. Meson weapons if affordable. Missile barrage if not. Mix of weapon types might be optimal.

 

[kilemall]

To the OP's original query, in general GG refueling is a bad thing for commercial vessels, among other things your passengers are not going to appreciate the delay, you have to pay for/risk longer periods of life support, you aren't optimizing your revenue time vs. mortgage payment overhead, and it gets you outside the starport protective envelope and into more dangerous 'waters' (gasses?).


Mainworlds around GGs may change the equation.


Otherwise I would expect this to be more the venue of smugglers- captain pleads poverty, goes to GG, meets small craft on pre-arranged flight plan in the GG's atmosphere under the noses of government, risky transfers of cargo are done, higher G small craft does more time 'submerged' to pop out in gaps in coverage.


This fits in with my conception of stealth, the extreme cost of covering all EM bands for something as big, heat-generating and energy emitting as a ship under maneuver would drive usage down to just small craft.

 

[nobby-w]

I think the tactical value of SDBs defending a gas giant is that they convert enemy refuelling operations from a ship turning up to refuel into something requiring cover and enough escort tonnage to take down the SDBs or at least make their commanders decide to remain in hiding. The deployment might not be intended to destroy the refuelling fleet but to deny the casual use of the system for refuelling by un-escorted ships, or to tie an enemy fleet up for an extended period hunting down the SDBs - effectively a commerce raiding function.

In this case, a relatively small force of SDBs could severely hamper the movements of a much larger enemy fleet. Their commanders could elect to remain hidden if the enemy arrived in force but pick off individual ships or smaller forces refuelling. A few hidden on main worlds or other locations insystem could also carry out this type of commerce raiding, tying up a disproportional amount of enemy fleet assets to hold the system or carry out search-and-destroy missions to clear the system.

 

[jawillroy]

Unfortunately, these are issues outside the scope of the combat systems presented in the game.

Has anyone done a workthrough for what's actually called for operationally in skimming, and for maintaining station in a GG?

Apparently a Free Trader can skim from a GG, so I suppose the skimming vessel needs at least that - but how powerful a drive do you need to get down into the clouds and out again?

Relating to this, what sort of modifier ought one to place on agility for a ship stuck down in the muck?

I recall the description of the SDB mentions the armored hull to withstand the pressure, but how much is called for?

An engagement occurring *in* a GG would naturally be occurring at short range, no?

 

[McPerth]

You may find this old thread about combats inside a Gas Giant interestin and relevant to the issues being discussed here...

 

[McPerth]

SDBs are a known quantity. An opposing fleet can predict about how many there will be and about how powerful they are, based on the tech level and wealth of the system that fields them. They can often be avoided - many systems can't field SDBs. One presumes systems that can field SDBs also have reasonable planetary defenses, or an attacker on detecting neutrinos would simply vector for the mainworld and leave the SDBs to choose between chasing them and engaging them without benefit of a gas giant to hide in or seeing them force a refueling at the mainworld under threat of bombardment.

So a hostile force arrives. It's there either because it has no other choice or because it wants to be there and is confident it can deal with the SDBs. If it's there because it had no other choice, the SDBs may be a substantial threat; it may opt to try a refueling under fire so it can jump out quick, rather than stay and fight it out. If it's there because it's confident it can deal with the SDBs, then what happens next depends on its long-term plans. It stays and bombards if it has the time, and the SDBs can rise to fight or make the fleet spend time killing them slowly in the depths, or if it's in a hurry it goes in to refuel and gives the SDBs a choice: die while contesting the refueling or let them refuel.

Inteligence in Traveller fleet operatins must always be taken with a grain of salt.

You sure have an idea about the SDB strength of a system, but even then you cannot know if it has been reinforced. If a system is important enough and there's only a Gas Giant, it can be reinforced with BRs acting as monitors (after all, their only difference is operational deployment, and it's to expect any Navy has extra BRs, as they are expected to sustain more loses than their Tenders), and any fleet relying on its intelligence about the system's SDB fleet can have a nasty surprise...

 

[Straybow]

There's a CT thread on Skimming.


My take (as posted in that thread) is that fuel scooping is more difficult than the hand wave it is normally given. It requires a liquefaction plant, which is large, and an internal collapsible holding tank, which is larger. It would probably increase dedicated fuel space by 10%, and could only be used when cargo isn't filled up to allow the holding tank to be expanded. Generally not worth it.